NIMP| Daniela PREDOI, Author at NIMP

Publications

1. Sodium bicarbonate-hydroxyapatite used for removal of lead ions from aqueous solution

Authors: Predoi, SA; Ciobanu, SC; Chifiriuc, CM; Iconaru, SL; Predoi, D; Negrila, CC; Marinas, IC; Raaen, S; Rokosz, K; Motelica-Heino, M

Published: JAN 1 2024, CERAMICS INTERNATIONAL, 50, DOI: 10.1016/j.ceramint.2023.10.273

This study reports the development of a novel biocomposite for potential applications in the environmental remediation. The hydroxyapatite/sodium bicarbonate (HAp-SB) biocomposite obtained by a cheap method could offer promising characteristics to be used in environmental applications. The obtaining of HAp-SB ceramic composites was studied with the aim of increasing the adsorption efficiency of lead ions from contaminated waters. A composite material (HAp-SB) with good crystallinity that preserves the hexagonal structure of pure hydroxyapatite was obtained. For the powder recovered after decontamination of the lead solution (PbHAp-SB), the XRD model highlighted additional maxima belonging to Ca10(PO4)5(OH)2, Ca0.805Pb4.195(PO4)(OH) and PbH2P2O7. The FTIR spectra of PbHAp-SB are similar to those of HAp-SB composites showing a broadening of the vibration peaks and a slight shift. The XPS and EDS studies illustrated the purity of the HAp-SB sample. Moreover, the presence of lead in the powder recovered after decontamination was also highlighted by XPS and EDS studies. The efficiency of HAp-SB in the adsorption of Pb2+ ions from the contaminated solution was also highlighted by ultrasound studies using double-distilled water as the reference liquid. The adsorption kinetics were investigated with the aid of Langmuir and Freundlich theoretical models. The results demonstrated that the HAp-SB ceramic composite has a strong affinity for the adsorption of Pb2+ ions from contaminated solutions. The removal efficiency of Pb2+ ions was about 92% for the initial Pb2+ concentration above 50 mg/L. The results of the cell viability and cytotoxicity studies demonstrated that HAp-SB nanoparticles did not influence negatively the HeLa cell's viability and did not induce any significant changes of the morphological features of HeLa cells after 24 h of incubation. The batch adsorption results as well as the cytotoxicity assay results suggested that the HAp-SB powder could be successfully used for the removal of Pb2+ from contaminated water.

2. New Physico-Chemical Analysis of Magnesium-Doped Hydroxyapatite in Dextran Matrix Nanocomposites

Authors: Predoi, D; Ciobanu, SC; Iconaru, SL; Talu, S; Ghegoiu, L; Matos, RS; da Fonseca, HD; Trusca, R

Published: JAN 2024, POLYMERS, 16, 125, DOI: 10.3390/polym16010125

The new magnesium-doped hydroxyapatite in dextran matrix (10MgHApD) nanocomposites were synthesized using coprecipitation technique. A spherical morphology was observed by scanning electron microscopy (SEM). The X-ray diffraction (XRD) characterization results show hydroxyapatite hexagonal phase formation. The element map scanning during the EDS analysis revealed homogenous distribution of constituent elements of calcium, phosphor, oxygen and magnesium. The presence of dextran in the sample was revealed by Fourier transform infrared (FTIR) spectroscopy. The antimicrobial activity of the 10MgHAPD nanocomposites was assessed by in vitro assays using Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Streptococcus mutans ATCC 25175, Porphyromonas gingivalis ATCC 33277 and Candida albicans ATCC 10231 microbial strains. The results of the antimicrobial assays highlighted that the 10MgHApD nanocomposites presented excellent antimicrobial activity against all the tested microorganisms and for all the tested time intervals. Furthermore, the biocompatibility assays determined that the 10MgHApD nanocomposites did not exhibit any toxicity towards Human gingival fibroblast (HGF-1) cells.

3. Morphological and fractal features of cancer cells anchored on composite layers based on magnesium-doped hydroxyapatite loaded in chitosan matrix

Authors: Talu, S; Matos, RS; da Fonseca, HD; Predoi, D; Iconaru, SL; Ciobanu, CS; Ghegoiu, L

Published: JAN 2024, MICRON, 176, 103548, DOI: 10.1016/j.micron.2023.103548

In the present study, we report the development and characterization of composite layers (by spin coating) based on magnesium-doped hydroxyapatite in a chitosan matrix, containing human osteosarcoma MG63 cells anchored. Studies regarding the biocompatibility of the composite layers were performed with the aid of a MTT (3-4,5-Dimethylthiazol 2,5-diphenyltetrazolium bromide) assay. The data determined that the composite layers did not inhibit the growth and adhesion of MG63 cells to their surfaces exhibiting good biocompatibility properties. Furthermore, the attachment and development of MG63 cells on the surface of MgHApCh composite layers were investigated using atomic force microscopy (AFM). AFM topographical maps emphasized that the HApCh and 8MgHApCh composite layers surface promoted the attachment and proliferation of MG63 cells on their surface. Meanwhile, in the case of 30MgHApCh layers incubated for 48 h, a slight modification of the morphological features of the MG63 cells. In addition, the effects of the composite layers against Candida albicans ATCC 10231 were also evaluated. The data results from the in vitro antifungal assay depicted that the composite layers successfully inhibited the growth of the fungal cells onto their surface. Morphological and fractal analyses unveil cancer cell surfaces on Mg-containing composite layers with intricate 3D patterns, driven by highfrequency components. Their remarkable complexity and roughness arises from a strong multifractal nature, supporting more effective vertical growth compared to Si and HApCh surfaces. The cell viability reduced of uncoated Si surface is highlighted by its less intense 3D pattern growth. Our results show that the uncoated Si surface promotes lower viability of MG63 cancer cells, with less rough and complex 3D spatial patterns.

4. Hydroxyapatite Nanopowders for Effective Removal of Strontium Ions from Aqueous Solutions

Authors: Predoi, SA; Ciobanu, SC; Chifiriuc, MC; Motelica-Heino, M; Predoi, D; Iconaru, SL

Published: JAN 2023, MATERIALS, 16, 229, DOI: 10.3390/ma16010229

Drinking water contamination has become a worldwide problem due to the highly negative effects that pollutants can have on human organisms and the environment. Hydroxyapatite (HAp) has the appropriate properties for the immobilization of various pollutants, being considered amongst the most cost-effective materials for water decontamination. The main objective of this study was to use synthesized hydroxyapatite for the elimination of Sr2+ ions from contaminated solutions. The hydroxyapatite used in the decontamination process was synthesized in the laboratory using an adapted method. The hydroxyapatite powder (HAp) resulting from the synthesis was analyzed both before and after the elimination of Sr2+ ions from contaminated solutions. The efficiency of the HAp nanoparticles in removing Sr2+ ions from contaminated solution was determined by batch adsorption experiments. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study the HAp samples before and after the removal of Sr2+ ions. The ability of HAp nanoparticles to eliminate strontium ions from contaminated solutions was established. Moreover, the removal of Sr2+ ions from the contaminated aqueous solutions was highlighted by ultrasound measurements. The value of the stability parameter calculated by ultrasonic measurements after the removal of Sr2+ ions from the contaminated solution was similar to that of double distilled water whose stability was used as reference. The outcomes of the batch experiments and the parameters obtained from Langmuir and Freundlich models indicated that the HAp nanoparticles had a strong affinity for the elimination of Sr2+ ions from polluted solutions. These results emphasized that HAp nanoparticles could be excellent candidates in the development of new technologies for water remediation. More than that, the outcomes of the cytotoxic assays proved that HAp nanoparticles did not induce any noticeable harmful effects against HeLa cells and did not affect their proliferation after 1 day and 7 days of incubation.

5. Salvia officinalis-Hydroxyapatite Nanocomposites with Antibacterial Properties

Authors: Ciobanu, SC; Predoi, D; Chifiriuc, MC; Iconaru, SL; Predoi, MV; Popa, M; Rokosz, K; Raaen, S; Marinas, IC; Huang, HM

Published: DEC 2023, POLYMERS, 15, 4484, DOI: 10.3390/polym15234484

In the present study, sage-coated zinc-doped hydroxyapatite was incorporated into a dextran matrix (7ZnHAp-SD), and its physico-chemical and antimicrobial activities were investigated. A 7ZnHAp-SD nanocomposite suspension was obtained using the co-precipitation method. The stability of the nanocomposite suspension was evaluated using ultrasound measurements. The stability parameter calculated relative to double-distilled water as a reference fluid highlights the very good stability of the 7ZnHAp-SD suspension. X-ray diffraction (XRD) experiments were performed to evaluate the characteristic diffraction peak of the hydroxyapatite phase. Valuable information regarding the morphology and chemical composition of 7ZnHAp-SD was obtained via scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) studies. Fourier-transform infrared spectroscopy (FTIR) measurements were performed on the 7ZnHAp-SD suspensions in order to evaluate the functional groups present in the sample. Preliminary studies on the antimicrobial activity of 7ZnHAp-SD suspensions against the standard strains of Staphylococcus aureus 25923 ATCC, Enterococcus faecalis 29212 ATCC, Escherichia coli 25922 ATCC, and Pseudomonas aeruginosa 27853 ATCC were conducted. More than that, preliminary studies on the biocompatibility of 7ZnHAp-SD were conducted using human cervical adenocarcinoma (HeLa) cells, and their results emphasized that the 7ZnHAp-SD sample did not exhibit a toxic effect and did not induce any noticeable changes in the morphological characteristics of HeLa cells. These preliminary results showed that these nanoparticles could be possible candidates for biomedical/antimicrobial applications.

6. Influence of the Biological Medium on the Properties of Magnesium Doped Hydroxyapatite Composite Coatings

Authors: Predoi, D; Ciobanu, SC; Iconaru, SL; Predoi, MV

Published: FEB 2023, COATINGS, 13, 409, DOI: 10.3390/coatings13020409

In this paper, the stability of magnesium-doped hydroxyapatite/chitosan (MHC) suspension obtained with the sol-gel approach was evaluated using nondestructive ultrasound measurements. The MHC coatings obtained by the spin-coating technique were characterized before and after immersion for 7 and 14 days, respectively, in Dulbecco's modified eagle medium (DMEM) by scanning electron microscopy, equipped with an EDAX detector. Also, the functional groups present on the MHC coatings surface were analyzed with the aid of attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. The surface microstructure was evaluated using two commentary techniques, namely atomic force microscopy (AFM) and metallographic microscopy (MM). The influence of immersion in DMEM on the biological properties was studied with in vitro studies using primary osteoblast and HCT-8 cell lines. Our results revealed that both surface morphology and chemical composition of the MHC coatings allow rapid development of a new apatite layer on their surface after immersion in DMEM. Preliminary in vitro biological studies underlined the noncytotoxic effect of the studied samples on the proliferation of primary osteoblast and HCT-8 cell lines, which makes them a promising candidate for applications in fields such as orthopedics or dentistry. The antifungal assay of the MHC coatings was assessed using Candida albicans ATCC 10231 and their results showed a good inhibitory effect. The coatings made on the basis of the MHC composite could contribute to increasing the degree of success of implants by decreasing the risk of infections and postoperative inflammation.

7. In Vitro and In Vivo Biological Assays of Dextran Coated Iron Oxide Aqueous Magnetic Fluids

Authors: Predoi, SA; Iconaru, SL; Predoi, D

Published: JAN 2023, PHARMACEUTICS, 15, 177, DOI: 10.3390/pharmaceutics15010177

The iron oxide nanoparticles coated with different surface coatings were studied and characterized by multiple physicochemical and biological methods. The present paper aims at estimating the toxicity in vitro and in vivo of dextran coated iron oxide aqueous magnetic fluids. The in vitro studies were conducted by quantifying the viability of HeLa cells after their incubation with the samples (concentrations of 62.5-125-250-500 mu g/mL at different time intervals). The estimation of the toxicity in vivo of administering dextran coated iron oxide aqueous magnetic fluids (DIO-AMF) with hydrodynamic diameter of 25.73 +/- 4 nm to Male Brown Norway rats has been made. Different concentrations (62.5-125-250-500 mu g/mL) of dextran coated iron oxide aqueous magnetic fluids were administered for 7 consecutive days. Hematology and biochemistry of the Male Brown Norway rats assessment was performed at various time intervals (24-72 h and 21-28 days) after intra-peritoneal injection. The results showed that high concentrations of DIO-AMF (250 and 500 mu g/mL) significantly increased white blood cells, red blood cells, hemoglobin and hematocrit compared to the values obtained for the control group (p < 0.05). Moreover, following the administration of DIO-AMF, the levels of alkaline phosphatase and aspartate aminotransferase increased compared to the control group (p < 0.05). After DIO-AMF administration, no significant difference was observed in the levels of alanine aminotransferase, gamma-glutamyl transpeptidase, urea and creatinine compared to the control group (p < 0.05). The results of the present study showed that dextran coated iron oxide aqueous magnetic fluids in concentrations lower than 250 mu g/mL are reliable for medical and pharmaceutical applications.

8. Biological Response of Human Gingival Fibroblasts to Zinc-Doped Hydroxyapatite Designed for Dental Applications-An In Vitro Study

Authors: Badea, MA; Balas, M; Popa, M; Borcan, T; Bunea, AC; Predoi, D; Dinischiotu, A

Published: JUN 2 2023, MATERIALS, 16, 4145, DOI: 10.3390/ma16114145

This study aimed to investigate the biological response induced by hydroxyapatite (HAp) and zinc-doped HAp (ZnHAp) in human gingival fibroblasts and to explore their antimicrobial activity. The ZnHAp (with xZn = 0.00 and 0.07) powders, synthesized by the sol-gel method, retained the crystallographic structure of pure HA without any modification. Elemental mapping confirmed the uniform dispersion of zinc ions in the HAp lattice. The size of crystallites was 18.67 +/- 2 nm for ZnHAp and 21.54 +/- 1 nm for HAp. The average particle size was 19.38 +/- 1 nm for ZnHAp and 22.47 +/- 1 nm for HAp. Antimicrobial studies indicated an inhibition of bacterial adherence to the inert substrate. In vitro biocompatibility was tested on various doses of HAp and ZnHAp after 24 and 72 h of exposure and revealed that cell viability decreased after 72 h starting with a dose of 31.25 mu g/mL. However, cells retained membrane integrity and no inflammatory response was induced. High doses (such as 125 mu g/mL) affected cell adhesion and the architecture of F-actin filaments, while in the presence of lower doses (such as 15.625 mu g/mL), no modifications were observed. Cell proliferation was inhibited after treatment with HAp and ZnHAp, except the dose of 15.625 mu g/mL ZnHAp at 72 h of exposure, when a slight increase was observed, proving an improvement in ZnHAp activity due to Zn doping.

9. Complex Evaluation of Nanocomposite-Based Hydroxyapatite for Biomedical Applications

Authors: Predoi, D; Iconaru, SL; Ciobanu, SC; Buton, N; Predoi, MV

Published: NOV 2023, BIOMIMETICS, 8, 528, DOI: 10.3390/biomimetics8070528

A magnesium-doped hydroxyapatite in chitosan matrix (MgHApC) sample was developed as a potential platform for numerous applications in the pharmaceutical, medical, and food industries. Magnesium-doped hydroxyapatite suspensions in the chitosan matrix were obtained by the coprecipitation technique. The surface shape and morphological features were determined by scanning electron microscopy (SEM). The hydrodynamic diameter of the suspended particles was determined by Dynamic light scattering (DLS) measurements. The stability of MgHApC suspensions was evaluated by ultrasonic measurements. The hydrodynamic diameter of the MgHApC particles in suspension was 29.5 nm. The diameter of MgHApC particles calculated from SEM was 12.5 +/- 2 nm. Following the SEM observations, it was seen that the MgHApC particles have a spherical shape. The Fourier-transform infrared spectroscopy (FTIR) studies conducted on MgHApC proved the presence of chitosan and hydroxyapatite in the studied specimens. In vitro antimicrobial assays were performed on Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231 microbial strains. The antimicrobial experiments showed that MgHApC exhibited very good antimicrobial properties against all the tested microorganisms. More than that, the results of the in vitro studies revealed that the antimicrobial properties of the samples depend on the incubation time. The evaluation of the sample's cytotoxicity was performed using the human colon cancer (HCT-8) cell line. Our results suggested the great potential of MgHApC to be used in future applications in the field of biomedical applications (e.g., dentistry, orthopedics, etc.).

10. Development of Novel Tetracycline and Ciprofloxacin Loaded Silver Doped Hydroxyapatite Suspensions for Biomedical Applications

Authors: Predoi, D; Iconaru, SL; Predoi, MV; Buton, N

Published: JAN 2023, ANTIBIOTICS-BASEL, 12, 74, DOI: 10.3390/antibiotics12010074

The objective of this study consisted of the development of new materials with antimicrobial properties at the nanometric scale that could lead to an increase in therapeutic efficacy and reduction of toxic side effects. This work focuses on obtaining and characterizing stable suspensions with narrow size distribution with antimicrobial properties. The stability of the suspensions obtained by an adapted co-precipitation method was evaluated by ultrasonic measurements. The size and size distribution of the particle populations were determined using scanning electron microscopy (SEM), and dynamic light scattering (DLS). Both methods of analysis showed a narrow distribution of particles. DLS gave a monomodal distribution with hydrodynamic diameters around 38 nm for ciprofloxacin embedded in silver doped hydroxyapatite (AgHA-C) and 45.7 nm for tetracycline embedded in silver doped hydroxyapatite (AgHA-T). The average diameters calculated from SEM were 17 nm for AgHA-C and 19 nm for AgHA-T. Both Ciprofloxacin and Tetracycline influenced the hydroxyapatite structure, which led to the appearance of new vibrational bands characteristic of the specific chemical composition in the FTIR spectrum. The antimicrobial properties of the AgHA-C and AgHA-T suspensions were assessed using the most common reference microbial strains Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Candida albicans ATCC 10231. The results of the in vitro antimicrobial assays determined that the AgHA-C and AgHA-T suspensions exhibited exceptional antimicrobial activity. Moreover, the data revealed that the antimicrobial activity increased with the increase of the incubation time.

11. New Insights into the Biological Response Triggered by Dextran-Coated Maghemite Nanoparticles in Pancreatic Cancer Cells and Their Potential for Theranostic Applications

Authors: Balas, M; Predoi, D; Burtea, C; Dinischiotu, A

Published: FEB 2023, INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES, 24, 3307, DOI: 10.3390/ijms24043307

Iron oxide nanoparticles are one of the most promising tools for theranostic applications of pancreatic cancer due to their unique physicochemical and magnetic properties making them suitable for both diagnosis and therapy. Thus, our study aimed to characterize the properties of dextran-coated iron oxide nanoparticles (DIO-NPs) of maghemite (gamma-Fe2O3) type synthesized by co-precipitation and to investigate their effects (low-dose versus high-dose) on pancreatic cancer cells focusing on NP cellular uptake, MR contrast, and toxicological profile. This paper also addressed the modulation of heat shock proteins (HSPs) and p53 protein expression as well as the potential of DIO-NPs for theranostic purposes. DIO-NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering analyses (DLS), and zeta potential. Pancreatic cancer cells (PANC-1 cell line) were exposed to different doses of dextran-coated gamma-Fe2O3 NPs (14, 28, 42, 56 mu g/mL) for up to 72 h. The results revealed that DIO-NPs with a hydrodynamic diameter of 16.3 nm produce a significant negative contrast using a 7 T MRI scanner correlated with dose-dependent cellular iron uptake and toxicity levels. We showed that DIO-NPs are biocompatible up to a concentration of 28 mu g/mL (low-dose), while exposure to a concentration of 56 mu g/mL (high-dose) caused a reduction in PANC-1 cell viability to 50% after 72 h by inducing reactive oxygen species (ROS) production, reduced glutathione (GSH) depletion, lipid peroxidation, enhancement of caspase-1 activity, and LDH release. An alteration in Hsp70 and Hsp90 protein expression was also observed. At low doses, these findings provide evidence that DIO-NPs could act as safe platforms in drug delivery, as well as antitumoral and imaging agents for theranostic uses in pancreatic cancer.

12. Response of the Endogenous Antioxidant Defense System Induced in RAW 264.7 Macrophages upon Exposure to Dextran-Coated Iron Oxide Nanoparticles

Authors: Balas, M; Iconaru, SL; Dinischiotu, A; Buton, N; Predoi, D

Published: FEB 2023, PHARMACEUTICS, 15, 552, DOI: 10.3390/pharmaceutics15020552

Presently, iron oxide nanoparticles are the only ones approved for clinical use as contrast agents in magnetic resonance imaging (MRI). Even though there is a high demand for these types of nanoparticles both for clinical use as well as for research, there are difficulties in obtaining stable nanoparticles with reproducible properties. In this context, in this study, we report the obtaining by an adapted coprecipitation method of dextran-coated maghemite nanoparticles (gamma-Fe2O3 NPs). The morphology and structure of the dextran-coated maghemite nanoparticles (gamma-Fe2O3 NPs) were determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The TEM and SEM micrographs highlighted the obtaining of particles of nanometric size and spherical shape morphology. Furthermore, the high-resolution transmission electron microscopy (HRTEM), as well as selected area diffraction (SAED), revealed that the obtained samples presented the structure of cubic maghemite. In this study, we also explored the effects of the co-precipitation synthesized dextran-coated maghemite nanoparticles (gamma-Fe2O3 NPs) on the redox status of macrophages. For cytotoxicity evaluation of these NPs, murine macrophages (RAW 264.7 cell line) were exposed to different concentrations of dextran-coated maghemite nanoparticles (gamma-Fe2O3 NPs) corresponding to 0-500 mu g Fe3+/mL and incubated for 24, 48, and 72 h. Intracellular iron uptake, changes in the oxidative stress parameters (reactive oxygen species production and malondialdehyde level), and the activity of antioxidant enzymes, as well as GSH concentration in cells, were evaluated after incubation with a lower (50 mu g Fe3+/mL) and higher (500 mu g Fe3+/mL) dose of NPs. The results indicated a significant decrease in RAW 264.7 cell viability after 72 h in the presence of NPs at concentrations above 25 mu g Fe3+/mL. An important accumulation of NPs, dependent on dose and exposure time, was detected in macrophages, but it induced only a limited raise in the oxidative status. We showed here that the antioxidant capacity of RAW 264.7 macrophages was efficient in counteracting dextran-coated maghemite nanoparticles (gamma-Fe2O3 NPs) toxicity even at higher doses.

13. Biocomposite Coatings Doped with Magnesium and Zinc Ions in Chitosan Matrix for Antimicrobial Applications

Authors: Predoi, D; Ciobanu, CS; Iconaru, SL; Raaen, S; Rokosz, K

Published: JUN 2023, MATERIALS, 16, 4412, DOI: 10.3390/ma16124412

Hydroxyapatite doped with magnesium and zinc in chitosan matrix biocomposites have great potential for applications in space technology, aerospace, as well as in the biomedical field, as a result of coatings with multifunctional properties that meet the increased requirements for wide applications. In this study, coatings on titanium substrates were developed using hydroxyapatite doped with magnesium and zinc ions in a chitosan matrix (MgZnHAp_Ch). Valuable information concerning the surface morphology and chemical composition of MgZnHAp_Ch composite layers were obtained from studies that performed scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), metallographic microscopy, and atomic force microscopy (AFM). The wettability of the novel coatings, based on magnesium and zinc-doped biocomposites in a chitosan matrix on a titanium substrate, was evaluated by performing water contact angle studies. Furthermore, the swelling properties, together with the coating's adherence to the titanium substrate, were also analyzed. The AFM results emphasized that the composite layers exhibited the surface topography of a uniform layer, and that there were no evident cracks and fissures present on the investigated surface. Moreover, antifungal studies concerning the MgZnHAp_Ch coatings were also carried out. The data obtained from quantitative antifungal assays highlight the strong inhibitory effects of MgZnHAp_Ch against C. albicans. Additionally, our results underline that after 72 h of exposure, the MgZnHAp_Ch coatings display fungicidal features. Thus, the obtained results suggest that the MgZnHAp_Ch coatings possess the requisite properties that make them suitable for use in the development of new coatings with enhanced antifungal features.

14. Dextran-Coated Iron Oxide Nanoparticles Loaded with 5-Fluorouracil for Drug-Delivery Applications

Authors: Predoi, D; Balas, M; Badea, MA; Ciobanu, SC; Buton, N; Dinischiotu, A

Published: JUN 2023, NANOMATERIALS, 13, 1811, DOI: 10.3390/nano13121811

This study aims to design and test different formulations composed of dextran-coated iron oxide nanoparticles (IONPs) loaded with 5-Fluorouracil (5-FU) with varying nanoparticle:drug ratios on colorectal cancer cells. The stable suspension of IONPs s was synthesized by the adapted co-precipitation method. The stable suspension of IONPs was mixed with a solution of dextran and 5-FU solubilized in a saline solution. The final suspensions with optimized ratios of IONP:5-FU in the final suspension were 0.5:1, 1:1, and 1.5:1. The information on the morphology and size distribution of the IONPs suspension and IONP loads with 5-FU was obtained using scanning electron microscopy (SEM). The presence of 5-FU and dextran on the surface of the IONPs was highlighted by energy-dispersive X-ray spectroscopy (EDS) studies. The determination of the surface charge of the nanoparticles in the final suspensions of IONP:5-FU was achieved by measuring the zeta potential (& zeta;). The hydrodynamic diameter of the resulting suspensions of IONP:5-FU was determined by dynamic light scattering (DLS). A cytocompatibility analysis was performed using Caco-2 (human epithelial colorectal adenocarcinoma) cells. In this research, our goal was to find a relationship between the formulation ratio of nanoparticles and drug, and the cellular response after exposure, as a strategy to increase the efficacy of this drug-delivery system. The nanoparticle uptake and antitumor activity, including modulation of oxidative stress, apoptosis, and proliferation biomarkers, were analyzed. The present study showed that the nanoformulation with the ratio IONP:5-FU 1.5:1 had the highest anti-tumor efficiency. Moreover, decreased MCM-2 expression in Caco-2 cells exposed to dextran-coated iron oxide nanoparticles loaded with 5-FU was demonstrated for the first time.

15. Studies of New Layer Formation on the Surface of Zinc Doped Hydroxyapatite/Chitosan Composite Coatings in Biological Medium

Authors: Motelica-Heino, M; Predoi, MV; Ciobanu, SC; Iconaru, SL; Predoi, D

Published: FEB 2023, COATINGS, 13, 472, DOI: 10.3390/coatings13020472

Usually, before being used in biomedical applications, a biomaterials' bioactivity is tested by in vitro methods that simulate similar conditions to those found in the human body. In this work, we report on the synthesis of zinc-doped hydroxyapatite-chitosan (ZnHApC) composite coatings by the vacuum deposition method. The surface microstructure and the chemical and molecular modification of the coatings before and after soaking in DMEM (Dulbecco's Modified Eagle's Medium) were studied. For this objective, techniques such as attenuated total reflection (ATR), Fourier transform infrared (FTIR) spectroscopy, metallographic microscopy (MM), and scanning electron microscopy (SEM) were applied used. Also, water contact angle measurements and swelling studies were made on ZnHApC composite coatings before and after soaking in a biological medium. The coatings' adherence to the substrate was also studied. The results of antifungal studies on ZnHApC composite coatings against the Candida albicans microbial strain reveal their good antifungal activity. The biocompatibility of the composite coatings was tested using a primary osteoblast cell line. Our results suggest that zinc-doped hydroxyapatite-chitosan samples could be used as a bioimplant material due to their enhanced bioactivity and biocompatibility.

16. Studies of the Tarragon Essential Oil Effects on the Characteristics of Doped Hydroxyapatite/Chitosan Biocomposites

Authors: Predoi, D; Iconaru, SL; Ciobanu, CS; Raita, MS; Ghegoiu, L; Trusca, R; Badea, ML; Cimpeanu, C

Published: APR 2023, POLYMERS, 15, 1908, DOI: 10.3390/polym15081908

Due to the emergence of antibiotic-resistant pathogens, the need to find new, efficient antimicrobial agents is rapidly increasing. Therefore, in this study, we report the development of new biocomposites based on zinc-doped hydroxyapatite/chitosan enriched with essential oil of Artemisia dracunculus L. with good antimicrobial activity. Techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) were used in order to evaluate their physico-chemical properties. Our studies revealed that biocomposite materials with nanometric dimension and homogeneous composition could be obtained through an economic and cost-effective synthesis method. The biological assays demonstrated that ZnHA (zinc-doped hydroxyapatite), ZnHACh (zinc-doped hydroxyapatite/chitosan) and ZnHAChT (zinc-doped hydroxyapatite/chitosan enriched with essential oil of Artemisia dracunculus L.) did not exhibit a toxic effect on the cell viability and proliferation of the primary osteoblast culture (hFOB 1.19). Moreover, the cytotoxic assay also highlighted that the cell morphology of the hFOB 1.19 was not altered in the presence of ZnHA, ZnHACh or ZnHAChT. Furthermore, the in vitro antimicrobial studies emphasized that the samples exhibited strong antimicrobial properties against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Candida albicans ATCC 10231 microbial strains. These results are encouraging for the following development of new composite materials with enhanced biological properties that could promote the osteogenic process of bone healing and also exhibit good antimicrobial properties.

17. Novel Dextran Coated Cerium Doped Hydroxyapatite Thin Films

Authors: Ciobanu, CS; Nica, IC; Dinischiotu, A; Iconaru, SL; Chapon, P; Bita, B; Trusca, R; Groza, A; Predoi, D

Published: MAY 2022, POLYMERS, 14, 1826, DOI: 10.3390/polym14091826

Dextran coated cerium doped hydroxyapatite (Ca(10-x)Cex(PO4)(6)(OH)(2)), with x = 0.05 (5CeHAp-D) and x = 0.1 (10CeHAp-D) were deposited on Si substrates by radio frequency magnetron sputtering technique for the first time. The morphology, composition, and structure of the resulting coatings were examined by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), atomic force microscopy (AFM), metallographic microscopy (MM), Fourier transform infrared spectroscopy (FTIR), and glow discharge optical emission spectroscopy (GDOES), respectively. The obtained information on the surface morphologies, composition and structure was discussed. The surface morphologies of the CeHAp-D composite thin films are smooth with no granular structures. The constituent elements of the CeHAp-D target were identified. The results of the FTIR measurements highlighted the presence of peaks related to the presence of nu(1), nu(3), and nu(4) vibration modes of (PO43-) groups from the hydroxyapatite (HAp) structure, together with those specific to the dextran structure. The biocompatibility assessment of 5CeHAp-D and 10CeHAp-D composite coatings was also discussed. The human cells maintained their specific elongated morphology after 24 h of incubation, which confirmed that the behavior of gingival fibroblasts and their proliferative capacity were not disturbed in the presence of 5CeHAp-D and 10CeHAp-D composite coatings. The 5CeHAp-D and 10CeHAp-D coatings' surfaces were harmless to the human gingival fibroblasts, proving good biocompatibility.

18. Development of Silver Doped Hydroxyapatite Thin Films for Biomedical Applications

Authors: Iconaru, SL; Predoi, D; Ciobanu, CS; Motelica-Heino, M; Guegan, R; Bleotu, C

Published: MAR 2022, COATINGS, 12, 341, DOI: 10.3390/coatings12030341

Silver doped hydroxyapatite [AgHAp, Ca10-xAg(PO4)(6)(OH)(2)], due to its antimicrobial properties, is an advantageous material to be used for various coatings. The AgHAp thin films with x(Ag) = 0.05 and x(Ag) = 0.1 were achieved using the spin-coating method. The resulting samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). XRD analysis revealed that the particles of both samples are ellipsoidal. Also, in agreement with the results obtained by XRD measurements, the results of the SEM studies have shown that the particles shape is ellipsoidal. Optical properties of silver doped hydroxyapatite thin films deposited on Si substrate were investigated through Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The results obtained by the two complementary techniques highlighted that the molecular structure of the studied samples is not influenced by the increase of the silver concentration in the samples. Our studies revealed that the surface morphology of the obtained samples consist of uniform and continuous layers. The biocompatibility of the obtained thin films was also evaluated with the aid of human osteosarcoma MG63 (ATCC CRL 1427) cell line. Moreover, the in vitro antifungal activity against Candida albicans fungal strain of the AgHAp thin films was studied and the obtained results revealed their antifungal effect. The results of the biological assays showed that the AgHAp thin films are a very promising material for biomedical applications.

19. Impact of Gamma Irradiation on the Properties of Magnesium-Doped Hydroxyapatite in Chitosan Matrix

Authors: Predoi, D; Ciobanu, CS; Iconaru, SL; Predoi, SA; Chifiriuc, MC; Raaen, S; Badea, ML; Rokosz, K

Published: AUG 2022, MATERIALS, 15, 5372, DOI: 10.3390/ma15155372

This is the first report regarding the effect of gamma irradiation on chitosan-coated magnesium-doped hydroxyapatite (x(Mg) = 0.1; 10 MgHApCh) layers prepared by the spin-coating process. The stability of the resulting 10 MgHApCh gel suspension used to obtain the layers has been shown by ultrasound measurements. The presence of magnesium and the effect of the irradiation process on the studied samples were shown by X-ray photoelectron spectroscopy (XPS). The XPS results obtained for irradiated 10 MgHApCh layers suggested that the magnesium and calcium contained in the surface layer are from tricalcium phosphate (TCP; Ca-3(PO4)(2)) and hydroxyapatite (HAp). The XPS analysis has also highlighted that the amount of TCP in the surface layer increased with the irradiation dose. The energy-dispersive X-ray spectroscopy (EDX) evaluation showed that the calcium decreases with the increase in the irradiation dose. In addition, a decrease in crystallinity and crystallite size was highlighted after irradiation. By atomic force microscopy (AFM) we have obtained images suggesting a good homogeneity of the surface of the non-irradiated and irradiated layers. The AFM results were also sustained by the scanning electron microscopy (SEM) images obtained for the studied samples. The effect of gamma-ray doses on the Fourier transform infrared spectroscopy (ATR-FTIR) spectra of 10 MgHApCh composite layers was also evaluated. The in vitro antifungal assays proved that 10 MgHApCh composite layers presented a strong antifungal effect, correlated with the irradiation dose and incubation time. The study of the stability of the 10 MgHApCh gel allowed us to achieve uniform and homogeneous layers that could be used in different biomedical applications.

20. Physicochemical Characterization of Europium-Doped Hydroxyapatite Thin Films with Antifungal Activity

Authors: Ciobanu, CS; Predoi, MV; Buton, N; Megier, C; Iconaru, SL; Predoi, D

Published: MAR 2022, COATINGS, 12, 306, DOI: 10.3390/coatings12030306

Owing to its unique biological and physicochemical properties, hydroxyapatite (HAp) represents one of the most extensively studied biomaterials for biomedical applications. It is well known that Candida is currently one of the fungi frequently involved in the onset and development of post-implant infections and, owing to the appearance of antifungal resistance, it is quite difficult to treat despite all the tremendous efforts made in this regard by the scientific world. Therefore, in this context, we report for the first time in this paper, the development and characterization of europium-doped thin films (5EuHAp, x(Eu) = 0.05) on a Si substrate by a spin-coating method. The results of ultrasound (US), zeta (zeta) potential, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) studies are presented. The XRD studies conducted on 5EuHAp suspension revealed the nanometric dimensions of the particles and sample purity. In addition, a moderate stability of the 5EuHAp suspension was observed. XPS measurements revealed the presence of Eu 3d in the 5EuHAp thin films. In the SEM micrographs, the surface uniformity and the absence of the surface defects could be observed. Moreover, the results of the FTIR studies showed the presence of the vibrational bands specific to the HAp structure in the studied sample. The antifungal activity of the HAp and 5EuHAp suspensions and coatings was evaluated using the Candida albicans ATCC 10231 (C. albicans) fungal strain. The qualitative assays of the antifungal properties of HAp and 5EuHAp coatings were also visualized by SEM and CLSM. The antifungal studies revealed that both 5EuHAp suspensions and coatings exhibited noticeable antifungal activity against C. albicans cells.

21. The Effects of Electron Beam Irradiation on the Morphological and Physicochemical Properties of Magnesium-Doped Hydroxyapatite/Chitosan Composite Coatings

Authors: Bita, B; Stancu, E; Stroe, D; Dumitrache, M; Ciobanu, SC; Iconaru, SL; Predoi, D; Groza, A

Published: FEB 2022, POLYMERS, 14, 582, DOI: 10.3390/polym14030582

This work reports on the influence of 5 MeV electron beam radiations on the morphological features and chemical structure of magnesium-doped hydroxyapatite/chitosan composite coatings generated by the magnetron sputtering technique. The exposure to ionizing radiation in a linear electron accelerator dedicated to medical use has been performed in a controllable manner by delivering up to 50 Gy radiation dose in fractions of 2 Gy radiation dose per 40 s. After the irradiation with electron beams, the surface of layers became nano-size structured. The partial detachment of irradiated layers from the substrates has been revealed only after visualizing their cross sections by scanning electron microscopy. The energy dispersive X-ray spectral analysis of layer cross-sections indicated that the distribution of chemical elements in the samples depends on the radiation dose. The X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction analysis have shown that the physicochemical processes induced by the ionizing radiation in the magnesium doped hydroxyapatite/chitosan composite coatings do not alter the apatite structure, and Mg remains bonded with the phosphate groups.

22. Physicochemical and Biological Evaluation of Chitosan-Coated Magnesium-Doped Hydroxyapatite Composite Layers Obtained by Vacuum Deposition

Authors: Predoi, D; Ciobanu, CS; Iconaru, SL; Raaen, S; Badea, ML; Rokosz, K

Published: MAY 2022, COATINGS, 12, 702, DOI: 10.3390/coatings12050702

In the present work, the effectiveness of vacuum deposition technique for obtaining composite thin films based on chitosan-coated magnesium-doped hydroxyapatite Ca10-xMgx(PO4)(6) (OH)(2) with x(Mg) = 0.025 (MgHApCh) was proved for the first time. The prepared samples were exposed to three doses (0, 3, and 6 Gy) of gamma irradiation. The MgHApCh composite thin films nonirradiated and irradiated were evaluated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) studies. The biological evaluation of the samples was also presented. All the results obtained from this study showed that the vacuum deposition method allowed for obtaining uniform and homogeneous layers. Fine cracks were observed on the MgHApCh composite thin films' surface after exposure to a 6 Gy irradiation dose. Additionally, after gamma irradiation, a decrease in Ca, P, and Mg content was noticed. The MgHApCh composite thin films with doses of 0 and 3 Gy of gamma irradiation showed a cellular viability similar to that of the control. Samples with 6 Gy doses of gamma irradiation did not cause significantly higher fibroblast cell death than the control (p > 0.05). On the other hand, the homogeneous distribution of pores that appeared on the surface of coatings after 6 Gy doses of gamma irradiation did not prevent the adhesion of fibroblast cells and their spread on the coatings. In conclusion, we could say that the thin films could be suitable both for use in bone implants and for other orthopedic and dentistry applications.

23. Iron-Oxide-Nanoparticles-Doped Polyaniline Composite Thin Films

Authors: Butoi, B; Ciobanu, CS; Iconaru, SL; Negrila, CC; Badea, MA; Balas, M; Dinischiotu, A; Predoi, G; Bita, B; Groza, A; Predoi, D

Published: MAY 2022, POLYMERS, 14, 1821, DOI: 10.3390/polym14091821

Iron-oxide-doped polyaniline (PANI-IO) thin films were obtained by the polymerization of aniline monomers and iron oxide solutions in direct current glow discharge plasma in the absence of a buffer gas for the first time. The PANI-IO thin films were deposited on optical polished Si wafers in order to study surface morphology and evaluate their in vitro biocompatibility. The characterization of the coatings was accomplished using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), metallographic microscopy (MM), and X-ray photoelectron spectroscopy (XPS). In vitro biocompatibility assessments were also conducted on the PANI-IO thin films. It was observed that a uniform distribution of iron oxide particles inside the PANI layers was obtained. The constituent elements of the coatings were uniformly distributed. The Fe-O bonds were associated with magnetite in the XPS studies. The surface morphology of the PANI-IO thin films was assessed by atomic force microscopy (AFM). The AFM topographies revealed that PANI-IO exhibited the morphology of a uniformly distributed and continuous layer. The viability of Caco-2 cells cultured on the Si substrate and PANI-IO coating was not significantly modified compared to control cells. Moreover, after 24 h of incubation, we observed no increase in LDH activity in media in comparison to the control. In addition, our results revealed that the NO levels for the Si substrate and PANI-IO coating were similar to those found in the control sample.

24. Fabrication and Physico-Chemical Properties of Antifungal Samarium Doped Hydroxyapatite Thin Films

Authors: Ciobanu, CS; Predoi, D; Chapon, P; Predoi, MV; Iconaru, SL

Published: DEC 2021, COATINGS, 11, DOI: 10.3390/coatings11121466

Samarium doped hydroxyapatite (Ca10-xSmx(PO4)(6)(OH)(2), x(Sm) = 0.5, 50SmHAp) is a very promising candidate to be used for different coatings in various dental and orthopedic implants. We report, for the first time, the obtaining of 50SmHAp thin films by a cost-effective method, namely spin coating. Thin films of 50SmHAp on silicon substrate have been analyzed by various techniques such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), Metallographic microscopy and Glow Discharge Optical Emission Spectroscopy (GDOES). The stability of 50SmHAp suspension was evaluated by ultrasound measurements. Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were also used to evaluate the 50SmHAp suspension. The antifungal activity of 50SmHAp suspension and coatings was assessed using Candida albicans ATCC 10231 fungal strain (C. albicans). The results of the antifungal assays depicted that both 50SmHAp suspensions and coatings were effective in inhibiting the development of C. albicans fungal cells, thus making them ideal candidates for the development of novel antifungal agents. The obtained results give new perspective for possible applications of 50SmHAp thin films in various medical applications due to their antifungal properties.

25. Investigation of Spin Coating Cerium-Doped Hydroxyapatite Thin Films with Antifungal Properties

Authors: Iconaru, SL; Predoi, MV; Chapon, P; Gaiaschi, S; Rokosz, K; Raaen, S; Motelica-Heino, M; Predoi, D

Published: APR 2021, COATINGS, 11, DOI: 10.3390/coatings11040464

In this study, the cerium-doped hydroxyapatite (Ca10-xCex(PO4)(6)(OH)(2) with x(Ce) = 0.1, 10Ce-HAp) coatings obtained by the spin coating method were presented for the first time. The stability of the 10Ce-HAp suspension particles used in the preparation of coatings was evaluated by ultrasonic studies, transmission electron microscopy (TEM), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The surface morphology of the 10Ce-HAp coating was studied by SEM and atomic force microscopy (AFM) techniques. The obtained 10Ce-HAp coatings were uniform and without cracks or unevenness. Glow discharge optical emission spectroscopy (GDOES) and X-ray photoelectron spectroscopy (XPS) were used for the investigation of fine chemical depth profiling. The antifungal properties of the HAp and 10Ce-HAp suspensions and coatings were assessed using Candida albicans ATCC 10231 (C. albicans) fungal strain. The quantitative antifungal assays demonstrated that both 10Ce-HAp suspensions and coatings exhibited strong antifungal properties and that they successfully inhibited the development and adherence of C. albicans fungal cells for all the tested time intervals. The scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) visualization of the C. albicans fungal cells adherence to the 10Ce-HAp surface also demonstrated their strong inhibitory effects. In addition, the qualitative assays also suggested that the 10Ce-HAp coatings successfully stopped the biofilm formation.

26. Fabrication of Novel Chitosan-Hydroxyapatite Nanostructured Thin Films for Biomedical Applications

Authors: Ciobanu, CS; Iconaru, SL; Predoi, D; Trusca, RD; Prodan, AM; Groza, A; Chifiriuc, MC; Beuran, M

Published: DEC 2021, COATINGS, 11, DOI: 10.3390/coatings11121561

In this study, we develop chitosan-hydroxyapatite (CS-HAp) composite layers that were deposited on Si substrates in radio frequency (RF) magnetron sputtering discharge in argon gas. The composition and structure of CS-HAp composite layers were investigated by analytical techniques, such as Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), metallographic microscopy (MM), and atomic force microscopy (AFM). On the other hand, in the present study the second order derivative of FT-IR-ATR spectra, for compositional analyses of CS-HAp, were used. The SEM, MM, and AFM data have shown the formation of CS-HAp composite layers. The surface of CS-HAp composite layers showed uniform growth (at an Ar gas working pressure of p = 2 x 10(-3) mbar). The surface of the CS-HAp composites coatings became more nanostructured, becoming granular as the gas pressure increased from 5 x 10(-3) to 1.2 x 10(-2) mbar. However, our studies revealed that the surface morphology of the CS-HAp composite layers varies with the Ar gas working pressure. At the same time, optical properties are slightly influenced by Ar pressure. Their unique physicochemical properties make them suitable for various applications in the biomedical field, if we consider the already proven antimicrobial properties of chitosan. The antifungal properties and the capacity of the CS-HAp composite layers to inhibit the development of fungal biofilms were also demonstrated using the Candida albicans ATCC 10231 (C. albicans) fungal strain.

27. Multi-Level Evaluation of UV Action upon Vitamin D Enhanced, Silver Doped Hydroxyapatite Thin Films Deposited on Titanium Substrate

Authors: Negrila, CC; Predoi, D; Ghita, RV; Iconaru, SL; Ciobanu, SC; Manea, M; Badea, ML; Costescu, A; Trusca, R; Predoi, G; Stanciu, GA; Hristu, R; Dragu, LD; Bleotu, C; Groza, A; Marinas, IC; Chifiriuc, MC

Published: FEB 2021, COATINGS, 11, DOI: 10.3390/coatings11020120

Hydroxyapatite Ca-10(PO4)(6)(OH)(2) (HAp) is an important bioactive material for bone tissue reconstruction, due to its highly thermodynamic stability at a physiological pH without bio-resorption. In the present study, the Ag:HAp and the corresponding Ag:HAp + D-3 thin films (similar to 200 nm) coating were obtained by vacuum deposition method on Ti substrate. The obtained samples were exposed to different UV irradiation times, in order to investigate the UV light action upon thin films, before considering this method for the thin film's decontamination. The effects of UV irradiation upon Ag:Hap + D-3 are presented for the first time in the literature, marking a turning point for understanding the effect of UV light on composite biomaterial thin films. The UV irradiation induced an increase in the initial stages of surface roughness of Ag:HAp thin film, correlated with the modifications of XPS and FTIR signals. The characteristics of thin films measured by AFM (RMS) analysis corroborated with XPS and FTIR investigation highlighted a process of recovery of the thin film's properties (e.g., RMS), suggesting a possible adaptation to UV irradiation. This process has been a stage to a more complicated UVA rapid degradation process. The antifungal assays demonstrated that all the investigated samples exhibited antifungal properties. Moreover, the cytotoxicity assays revealed that the HeLa cells morphology did not show any alterations after 24 h of incubation with the Ag:HAp and Ag:HAp + D-3 thin films.

28. Nitrogen and Bromide Co-Doped Hydroxyapatite Thin Films with Antimicrobial Properties

Authors: Iconaru, SL; Ciobanu, CS; Predoi, D; Motelica-Heino, M; Negrila, CC; Badea, ML; Predoi, MV; Chifiriuc, CM; Popa, M

Published: DEC 2021, COATINGS, 11, DOI: 10.3390/coatings11121505

Hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HAp), due to its high biocompatibility, is widely used as biomaterial. Doping with various ions of hydroxyapatite is performed to acquire properties as close as possible to the biological apatite present in bones and teeth. In this research the results of a study performed on thin films of hydroxyapatite co-doped with nitrogen and bromine (NBrHAp) are presented for the first time. The NBrHAp suspension was obtained by performing the adapted co-precipitation method using cetyltrimethylammonium bromide (CTAB). The thin layers of NBrHAp were obtained by spin-coating. The stability of the NBrHAp suspension was examined by ultrasound measurements. The thin layers obtained by the spin-coating method were examined by scanning electron microscopy (SEM), optical microscopy (OM), and metallographic microscopy (MM). The presence of nitrogen and bromine were highlighted by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) studies. Fourier transform infrared spectroscopy (FTIR) was used to highlight the chemical status of nitrogen and bromine. In addition, the powder obtained from the NBrHAp suspension was analyzed by XRD. Moreover, the in vitro antimicrobial activity of the NBrHAp suspensions and coatings was investigated using the reference microbial strains Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Candida albicans ATCC 10231. The results highlighted the successful obtainment of N and Br co-doped hydroxyapatite suspension for the first time by an adapted co-precipitation method. The obtained suspension was used to produce pure NBrHAp composite thin films with superior morphological properties. The NBrHAp suspensions and coatings exhibited in vitro antimicrobial activity against bacterial and fungal strains and revealed their good antimicrobial activity.

29. Biocompatibility and Antibiofilm Properties of Samarium Doped Hydroxyapatite Coatings: An In Vitro Study

Authors: Nica, IC; Popa, M; Marutescu, L; Dinischiotu, A; Iconaru, SL; Ciobanu, SC; Predoi, D

Published: OCT 2021, COATINGS, 11, DOI: 10.3390/coatings11101185

The implant-related infection as a consequence of bacterial adherence and biofilm formation remains one of the main causes of implant failure. Grace to recent advances in materials science, their great mechanical properties and their biocompatibility (both in vitro and in vivo), antibacterial coatings have gradually become a primary component of the global strategy for preventing microbial colonization. In the present work, novel antibacterial coatings containing hydroxyapatite nanoparticles doped with two different concentrations of samarium (5SmHAp and 10SmHAp) were obtained on Si substrates using the dip coating method. The morphology and physicochemical properties of these modified surfaces were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). In addition, their antimicrobial effects and biocompatibility were assessed. The results showed a continuous and homogeneous layer, uniformly deposited, with no cracks or impurities. 5SmHAp and 10SmHAp surfaces exhibited significant antibiofilm activity and good biocompatibility without inducing cytotoxic effects in human gingival fibroblasts. All these findings indicate that samarium doped hydroxyapatite coatings could be great candidates for the development of new antimicrobial strategies.

30. THE EFFECT OF HYDROXYAPATITE AND IRONE OXIDE NANOPARTICLES ON MAIZE AND WINTER WHEAT PLANTS

Authors: Petcu, E; Lazar, C; Predoi, D; Cimpeanu, C; Predoi, G; Bartha, S; Vlad, IA; Partal, E

Published: 2021, SCIENTIFIC PAPERS-SERIES A-AGRONOMY, 64, 519, DOI:

In the last few decades, the intensive use of agricultural lands affected crop productivity and thus raised serious concerns due to competing demands for food to feed the ever-growing world population (projected to be 9.7 billion by 2050). In this context, the development of nanotechnology-based fertilizers for crop nutrition has been suggested as an alternative tool to overcome the drawbacks arising from the current agricultural practices. Unfortunathelly, there is little studies about the effects of nanomaterials on plants. In this study we presented the effect of hydroxyapatite (nHA) and iron oxides (nIO) nanoparticles obtained in Romania on growth and photosintesis of corn and winter wheat plants. The results show that hydroxyapatite (nHA) and iron oxides (nIO) treatments applied by watering the soil had a positive effect on the photosynthesis of maize and winter wheat plants. In the case of treatments with solutions of iron oxides a negative effect on the length of main root was observation, but a compensating effect was found by increasing root density. This and also the higher chlorophyll content. led to a positive effect on height of maize and winter wheat plants.

31. Preparation and Characterization of Dextran Coated Iron Oxide Nanoparticles Thin Layers

Authors: Predoi, G; Ciobanu, CS; Iconaru, SL; Predoi, D; Dreghici, DB; Groza, A; Barbuceanu, F; Cimpeanu, C; Badea, ML; Barbuceanu, SF; Furnaris, CF; Belu, C; Ghegoiu, L; Raita, MS

Published: JUL 2021, POLYMERS, 13, DOI: 10.3390/polym13142351

In the present study, we report the synthesis of a dextran coated iron oxide nanoparticles (DIO-NPs) thin layer on glass substrate by an adapted method. The surface morphology of the obtained samples was analyzed by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), optical, and metallographic microscopies. In addition, the distribution of the chemical elements into the DIO-NPs thin layer was analyzed by Glow Discharge Optical Emission Spectrometry (GDOES). Furthermore, the chemical bonds formed between the dextran and iron oxide nanoparticles was investigated by Fourier Transform Infrared Spectroscopy (FTIR). Additionally, the HepG2 viability incubated with the DIO-NPs layers was evaluated at different time intervals using MTT (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The goal of this study was to obtain a DIO-NPs thin layer which could be used as a coating for medical devices such as microfluidic channel, microchips, and catheter. The results of the surface morphology investigations conducted on DIO-NPs thin layer suggests the presence of a continuous and homogeneous layer. In addition, the GDOES results indicate the presence of C, H, Fe, and O signal intensities characteristic to the DIO-NPs layers. The presence in the IR spectra of the Fe-CO metal carbonyl vibration bonds prove that the linkage between iron oxide nanoparticles and dextran take place through carbon-oxygen bonds. The cytotoxicity assays highlighted that HepG2 cells morphology did not show any noticeable modifications after being incubated with DIO-NPs layers. In addition, the MTT assay suggested that the DIO-NPs layers did not present any toxic effects towards HEpG2 cells.

32. The Physico-Chemical Properties and Exploratory Real-Time Cell Analysis of Hydroxyapatite Nanopowders Substituted with Ce, Mg, Sr, and Zn (0.5-5 at.%)

Authors: Chirica, IM; Enciu, AM; Tite, T; Dudau, M; Albulescu, L; Iconaru, SL; Predoi, D; Pasuk, I; Enculescu, M; Radu, C; Mihalcea, CG; Popa, AC; Rusu, N; Nita, S; Tanase, C; Stan, GE

Published: JUL 2021, MATERIALS, 14, DOI: 10.3390/ma14143808

Cation-substituted hydroxyapatite (HA), standalone or as a composite (blended with polymers or metals), is currently regarded as a noteworthy candidate material for bone repair/regeneration either in the form of powders, porous scaffolds or coatings for endo-osseous dental and orthopaedic implants. As a response to the numerous contradictions reported in literature, this work presents, in one study, the physico-chemical properties and the cytocompatibility response of single cation-doped (Ce, Mg, Sr or Zn) HA nanopowders in a wide concentration range (0.5-5 at.%). The modification of composition, morphology, and structure was multiparametrically monitored via energy dispersive X-ray, X-ray photoelectron, Fourier-transform infrared and micro-Raman spectroscopy methods, as well as by transmission electron microscopy and X-ray diffraction. From a compositional point of view, Ce and Sr were well-incorporated in HA, while slight and pronounced deviations were observed for Mg and Zn, respectively. The change of the lattice parameters, crystallite size, and substituting cation occupation factors either in the Ca(I) or Ca(II) sites were further determined. Sr produced the most important HA structural changes. The in vitro biological performance was evaluated by the (i) determination of leached therapeutic cations (by inductively coupled plasma mass spectrometry) and (ii) assessment of cell behaviour by both conventional assays (e.g., proliferation-3-(4,5-dimethyl thiazol-2-yl) 5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay; cytotoxicity-lactate dehydrogenase release assay) and, for the first time, real-time cell analysis (RTCA). Three cell lines were employed: fibroblast, osteoblast, and endothelial. When monophasic, the substituted HA supported the cells' viability and proliferation without signs of toxicity. The RTCA results indicate the excellent adherence of cells. The study strived to offer a perspective on the behaviour of Ce-, Mg-, Sr-, or Zn-substituted HAs and to deliver a well-encompassing viewpoint on their effects. This can be highly important for the future development of such bioceramics, paving the road toward the identification of candidates with highly promising therapeutic effects.

33. Development of Iron-Doped Hydroxyapatite Coatings

Authors: Predoi, D; Iconaru, SL; Ciobanu, SC; Predoi, SA; Buton, N; Megier, C; Beuran, M

Published: FEB 2021, COATINGS, 11, DOI: 10.3390/coatings11020186

It is known that iron is found as a trace element in bone tissue, the main inorganic constituent of which is hydroxyapatite. Therefore, iron-doped hydroxyapatite (HApFe) materials could be new alternatives for many biomedical applications. A facile dip coating process was used to elaborate the iron-doped hydroxyapatite (HApFe) nanocomposite coatings. The HApFe suspension used to prepare the coatings was achieved using a co-precipitation method, which was adapted in the laboratory. The quality of the HApFe suspension was assessed through dynamic light scattering (DLS), ultrasonic measurements, and zeta potential values. The hydroxyapatite XRD patterns were observed in the HApFe nanocomposite with no significant shifting of peak positions, thus suggesting that the incorporation of iron did not significantly modify the hydroxyapatite structure. The morphology of the HApFe nanoparticles was evaluated using transmission electron microscopy (TEM). Scanning electron microscopy (SEM) was used in order to investigate the morphologies of HApFe particles and coatings, while their chemical compositions were assessed using energy-dispersive X-ray spectroscopy (EDS). The SEM results suggested that the HApFe consists mainly of spherical nanometric particles and that the surfaces of the coatings are continuous and homogeneous. Additionally, the EDS spectra highlighted the purity of the samples and confirmed the presence of calcium, phosphorous, and iron in the analyzed sample. The in vitro cytotoxicity of the HApFe suspensions and coatings was evidenced using osteoblast cells. The MTT assay showed that both the HApFe suspensions and coatings exhibited biocompatible properties.

34. TiO2 nanoparticles coated with bio-inspired ligands for the safer-by-design development of photocatalytic paints

Authors: Laisney, J; Rosset, A; Bartolomei, V; Predoi, D; Truffier-Boutry, D; Artous, S; Berge, V; Brochard, G; Michaud-Soret, I

Published: JAN 1 2021, ENVIRONMENTAL SCIENCE-NANO, 8, 310, DOI: 10.1039/d0en00947d

Addition of titanium dioxide nanoparticles (TiO2 NPs) in photocatalytic paints represents a promising alternative aiming to mineralize gaseous pollutants, such as volatile organic compounds (VOCs). However, the risks of release of nanoparticles to human health and the environmental impact have to be taken carefully into account for their development. To take into account these risks, we develop a new method of TiO2 NP synthesis. Here, we report the electrostatic stabilization in aqueous medium with pyrophosphate buffers of different pH ranges followed by coating with bio-inspired molecules (lysine, deferoxamine, dopamine) and polymers (polyacrylic acid, polyethylene glycol, polydopamine) of 4-5 nm spherical photocatalytic TiO2 NPs for the development of safer-by-design photocatalytic paint. Characterization of the so-formed TiO2 nanocomposites by dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS) showed the good grafting of the ligands on the TiO2 surface and an enhanced stability in water compared to the pristine TiO2 NPs. The photocatalytic activity of the TiO2 nanocomposites was investigated by following the degradation of methylene blue (MB) under irradiation. The results showed a modulation of the photocatalytic activity (decrease or increase of the MB degradation rate) as a function of the nature/binding strength of the bio-inspired coating on the oxide surface. Finally, the most promising nanocomposites were incorporated in paints on which preliminary chalking assays were performed after storage for one year in the dark or in interior daylight.

35. Removal and Oxidation of As(III) from Water Using Iron Oxide Coated CTAB as Adsorbent

Authors: Predoi, D; Iconaru, SL; Predoi, MV; Motelica-Heino, M

Published: AUG 2020, POLYMERS, 12, DOI: 10.3390/polym12081687

Iron oxides such as magnetite and maghemite coated with cetyltrimethylammonium bromide (CTAB) are very promising materials for wastewater treatment because iron oxide can be easily separated from solutions using the magnetic separation procedure Iron oxide (IO) coated CTAB was synthesized by an adapted co-precipitation method. In the present study, the IO-CTAB was used for removing arsenic from water for the first time. In the present study, the performance of iron oxide coated CTAB biocomposites as an adsorbent for arsenic removal from aqueous solutions was examined. X-ray diffraction (XRD) analysis and the results revealed a cubic phase Fd-3 m of Fe(3)O(4)with lattice a = 8.40 angstrom and average crystal size equal to 17.26 +/- 3 nm. The mean particle size calculated from transmission electron microscopy (TEM) was 19.86 +/- 1.7 nm. The results of the adsorption batch experiments and the data determined using the Langmuir and Freundlich models emphasized that IO-CTAB nanoparticles were favorable for the adsorption of As(III) ions from aqueous solutions. Ultrasound measurements have shown that IO-CTAB is a cost-effective biocomposite for removing arsenic from contaminated solutions. Moreover, x-ray photoelectron spectroscopy (XPS) has shown that during the process of arsenic absorption, there is oxidation from As(III) to As(V), which leads to a decrease in toxicity during this process. The results of the cytotoxic assays confirmed that the IO-CTAB nanoparticles did not induce any morphological changes in the HeLa cells and did not affect their proliferation after 24 h of incubation.

36. Multifunctional Hydroxyapatite Coated with Arthemisia absinthium Composites

Authors: Raita, MS; Iconaru, SL; Groza, A; Cimpeanu, C; Predoi, G; Ghegoiu, L; Badea, ML; Chifiriuc, MC; Marutescu, L; Trusca, R; Furnaris, CF; Turculet, CS; Enache, DV; Predoi, D

Published: JAN 2 2020, MOLECULES, 25, DOI: 10.3390/molecules25020413

There is significant research showing that essential oils extracted from the plants have antibacterial effects. The purpose of this study was to develop a biocomposite based on hydroxyapatite coated with Artemisia absinthium essential oil and to highlight its antibacterial activity. Therefore, present studies are aimed at developing new materials combining hydroxyapatite with Artemisia absinthium essential oil, in order to avoid postoperative infections. The purpose of this work is to highlight the antimicrobial properties of the Artemisia absinthium essential oil-hydroxyapatite composites obtained by a simple method and at low costs. The structural properties and antimicrobial efficiency of the Artemisia absinthium essential oil-hydroxyapatite composite have been studied. The samples based on Artemisia absinthium essential oil analyzed in this study showed that wormwood essential oil presented the highest efficacy against the fungal strain of C. parapsilosis. It has been shown that wormwood essential oil has a strong antimicrobial effect against the microbial strains tested in this study. Furthermore, the antimicrobial properties of the biocomposites based on hydroxyapatite and essential oil are due to the presence of the essential oil in the samples.

37. Development of Cerium-Doped Hydroxyapatite Coatings with Antimicrobial Properties for Biomedical Applications

Authors: Predoi, D; Iconaru, SL; Predoi, MV; Groza, A; Gaiaschi, S; Rokosz, K; Raaen, S; Negrila, CC; Prodan, AM; Costescu, A; Badea, ML; Chapon, P

Published: JUN 2020, COATINGS, 10, DOI: 10.3390/coatings10060516

Antibacterial cerium-doped hydroxyapatite (Ce-HAp) layers have been researched sparingly in recent years. The Ce-HAp powder, Ca10-xCex(PO4)(6)(OH()2)with x(Ce)= 0.05, was obtained by an adapted chemical co-precipitation method at room temperature. The target was prepared using the Ce-HAp (x(Ce)= 0.05) powder sintered in air at 600 degrees C. The coatings on the Ti substrate were generated in plasma using a radio frequency (RF) magnetron sputtering discharge in an Ar gas flow in a single run. To collect the most complete information regarding the antimicrobial activity of cerium-doped hydroxyapatite with x(Ce)= 0.05, (5Ce-HAp), antimicrobial studies were carried out both on the final suspensions and on the coated surfaces. The target was tested using ultrasound measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), glow-discharge optical emission spectroscopy (GDOES), and X-ray photoelectron spectroscopy (XPS). The present study exhibited for the first time results of the homogeneous coatings of hydroxyapatite doped with cerium using a radio frequency magnetron sputtering technique. In addition, this study highlighted for the first time the stability of the cerium-doped hydroxyapatite gels used in the creation of the coating. Ultrasound measurements on the concentrated suspension of 5Ce-HAp showed a good stability compared to double distilled, water which was chosen as the reference fluid. Particles with spherical shape were observed by both TEM and SEM analysis. The broadening of the IR bands in the IR spectrum of the 5Ce-HAp film in comparison with the IR spectrum of the precursor target indicate the formation of interlinked bonds into the layer bulk. XPS analysis revealed that the mixture of Ce(3+)and Ce(4+)ions in the hydroxyapatite (HAp) structure of the coatings could be due to the deposition process. The surface of 5Ce-HAp coatings was homogenous with particles having a spherical shape. A uniform distribution of all the constituent elements on the surface the 5Ce-HAp layer was revealed. The antimicrobial assays proved that both 5Ce-HAp suspensions and 5Ce-HAp coatings effectively inhibited the development of colony forming units (CFU) for all the tested microbial strains. Moreover, the antimicrobial assays emphasized that the 5Ce-HAp suspensions had a biocide effect against Escherichia coli (E. coli) andCandida albicans(C. albicans)microbial strains after 72 h of incubation.

38. Dextran-Thyme Magnesium-Doped Hydroxyapatite Composite Antimicrobial Coatings

Authors: Iconaru, SL; Predoi, MV; Motelica-Heino, M; Predoi, D; Buton, N; Megier, C; Stan, GE

Published: JAN 2020, COATINGS, 10, DOI: 10.3390/coatings10010057

The dextran-thyme magnesium-doped hydroxyapatite (10MgHAp-Dex-thyme) composite layers were prepared by a dip-coating procedure from stable suspensions and further analyzed for the first time. Different characterization techniques were employed to explore the physical-chemical features of the 10MgHAp-Dex-thyme suspensions and derived coatings. Information regarding the 10MgHAp-Dex-thyme suspensions was extracted on the basis of dynamic light scattering, zeta potential, and ultrasound measurements. The crystalline quality of the biocomposite powders-resulting after the centrifugation of suspensions-and the layers deposited on glass was assessed by X-ray diffraction in symmetric and grazing incidence geometries, respectively. The chemical structure and presence of functional groups were evaluated for both powder and coating by Fourier transform infrared spectroscopy in attenuated total reflectance mode. The extent of the antimicrobial effect range of the biocomposite suspensions and coatings was tested against different Gram-positive and Gram-negative bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa) and fungus (Candida albicans) strains with promising results.

39. Obtaining and Characterizing Thin Layers of Magnesium Doped Hydroxyapatite by Dip Coating Procedure

Authors: Predoi, D; Iconaru, SL; Predoi, MV; Motelica-Heino, M; Buton, N; Megier, C

Published: JUN 2020, COATINGS, 10, DOI: 10.3390/coatings10060510

A simple dip coating procedure was used to prepare the magnesium doped hydroxyapatite coatings. An adapted co-precipitation method was used in order to obtain a Ca25-xMgx(PO4)(6)(OH)(2), 25MgHAp (x(Mg)= 0.25) suspension for preparing the coatings. The stabilities of 25MgHAp suspensions were evaluated using ultrasound measurements, zeta potential (ZP), and dynamic light scattering (DLS). Using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) information at nanometric resolution regarding the shape and distribution of the 25MgHAp particles in suspension was obtained. The surfaces of obtained layers were evaluated using SEM and atomic force microscopy (AFM) analysis. The antimicrobial evaluation of 25MgHAp suspensions and coatings on various bacterial strains and fungus were realized. The present study presents important results regarding the physico-chemical and antimicrobial studies of the magnesium doped hydroxyapatite suspensions, as well as the coatings. The studies have shown that magnesium doped hydroxyapatite suspensions prepared withx(Mg)= 0.25 presented a good stability and relevant antimicrobial properties. The coatings made using 25MgHAp suspension were homogeneous and showed remarkable antimicrobial properties. Also, it was observed that the layer realized has antimicrobial properties very close to those of the suspension. Both samples of the 25MgHAp suspensions and coatings have very good biocompatible properties.

40. Antimicrobial Properties of Samarium Doped Hydroxyapatite Suspensions and Coatings

Authors: Iconaru, SL; Groza, A; Gaiaschi, S; Rokosz, K; Raaen, S; Ciobanu, SC; Chapon, P; Predoi, D

Published: NOV 2020, COATINGS, 10, DOI: 10.3390/coatings10111124

Post-implant infections are a major health problem, and it is well-known that treating them with conventional drugs is accompanied by many disadvantages. The development of new biomaterials with enhanced antimicrobial properties are of major interest for the scientific world. The aim of this study was to synthesize and characterize hydroxyapatite doped with Samarium (Ca10-xSmx(PO4)(6)(OH)(2), x(Sm) = 0.05, 5Sm-HAp) suspensions, pellets and coatings. The 5Sm-HAp coatings on Si substrates were obtained by rf magnetron sputtering technique. The different techniques such as ultrasound measurements, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Glow Discharge Optical Emission Spectroscopy (GDOES), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to examine the obtained coatings. The results showed that the doped Sm ions entered the structure of hydroxyapatite successfully and Sm ions was uniformly doped onto the surface of the support. The depth profile curves of Ca, P, O, H, Ce and Si elements exhibit their presence from a surface to substrate interface as function of sputtering time. XPS analysis indicated as calcium-phosphate structures enriched in Sm3+ ions. Furthermore, the antimicrobial properties of the 5Sm-HAp suspensions, targets and coatings were assessed against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Candida albicans ATCC 10231. The results of the antimicrobial assays highlighted that that the samples presented a strong antimicrobial activity against the tested microbial strains. The results showed that the coatings after 48 h of incubation inhibited the growth of all tested microbial strains under the value of 0.6 Log CFU/mL. This study shows that the 5Sm-HAp samples are good candidates for the development of new antimicrobial agents.

41. Physico-Chemical Properties and In Vitro Antifungal Evaluation of Samarium Doped Hydroxyapatite Coatings

Authors: Ciobanu, SC; Iconaru, SL; Predoi, D; Prodan, AM; Predoi, MV

Published: SEP 2020, COATINGS, 10, DOI: 10.3390/coatings10090827

Hydroxyapatite (HAp) and samarium doped hydroxyapatite, Ca10-xSmx(PO4)(6)(OH)(2),x(Sm)= 0.05, (5SmHAp), coatings were prepared by sol-gel process using the dip coating method. The stability of 5SmHAp suspension was evaluated by ultrasound measurements. Fourier transform infrared spectroscopy (FTIR) was used to examine the optical characteristics of HAp and 5SmHAp nanoparticles in suspension and coatings. The FTIR analysis revealed the presence of the functional groups specific to the structure of hydroxyapatite in the 5SmHAp suspensions and coatings. The morphology of 5SmHAp nanoparticles in suspension was evaluated by transmission electron microscopy (TEM). Moreover, scanning electron microscope (SEM) was used to evaluate the morphology of nanoparticle in suspension and the morphology of the surface on the coating. The SEM and TEM studies on 5SmHAp nanoparticles in suspension showed that our samples consist of nanometric particles with elongated morphology. The SEM micrographs of HAp and 5SmHAp coatings pointed out that the coatings are continuous and homogeneous. The surface morphology of the 5SmHAp coatings was also assessed by Atomic Force Microscopy (AFM) studies. The AFM results emphasized that the coatings presented the morphology of a uniformly deposited layer with no cracks and fissures. The crystal structure of 5SmHAp coating was characterized by X-ray diffraction (XRD). The surface composition of 5SmHAp coating was analyzed by X-ray photoelectron spectroscopy (XPS). The XRD and XPS analysis shown that the Sm(3+)ions have been incorporated into the 5SmHAp synthesized material. The antifungal properties of the 5SmHAp suspensions and coatings were studied usingCandida albicansATCC 10231 (C. albicans) fungal strains. The quantitative results of the antifungal assay showed that colony forming unity development was inhibited from the early phase of adherence in the case of both suspensions and coatings. Furthermore, the adhesion, cell proliferation and biofilm formation of theC. albicanswere also investigated by AFM, SEM and Confocal Laser Scanning Microscopy (CLSM) techniques. The results highlighted that theC. albicansadhesion and cell development was inhibited by the 5SmHAp coatings. Moreover, the data also revealed that the 5SmHAp coatings were effective in stopping the biofilm formation on their surface. The toxicity of the 5SmHap was also investigated in vitro using HeLa cell line.

42. Chitosan-Hydroxyapatite Composite Layers Generated in Radio Frequency Magnetron Sputtering Discharge: From Plasma to Structural and Morphological Analysis of Layers

Authors: Dreghici, DB; Butoi, B; Predoi, D; Iconaru, SL; Stoican, O; Groza, A

Published: DEC 2020, POLYMERS, 12, DOI: 10.3390/polym12123065

Chitosan-hydroxyapatite composite layers were deposited on Si substrates in radio frequency magnetron sputtering discharges. The plasma parameters calculated from the current-voltage radio frequency-compensated Langmuir probe characteristics indicate a huge difference between the electron temperature in the plasma and at the sample holder. These findings aid in the understanding of the coagulation pattern of hydroxyapatite-chitosan macromolecules on the substrate surface. An increase in the sizes of the spherical-shape grain-like structures formed on the coating surface with the plasma electron number density was observed. The link between the chemical composition of the chitosan-hydroxyapatite composite film and the species sputtered from the target or produced by excitation/ionization mechanisms in the plasma was determined on the basis of X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and residual gas mass spectrometry analysis.

43. Fabrication of Silver- and Zinc-Doped Hydroxyapatite Coatings for Enhancing Antimicrobial Effect

Authors: Predoi, D; Iconaru, SL; Predoi, MV

Published: SEP 2020, COATINGS, 10, DOI: 10.3390/coatings10090905

This study develops, for the first time, composite coatings based on silver and zinc doped hydroxyapatite in chitosan matrix (AgZnHApCs). The AgZnHApCs composite coatings were prepared by dip coating method. The hydroxyapatite (HAp), biocompatible material for regenerating and strengthening damaged bones were doped with silver and zinc ions and coated with chitosan in order to produce a uniform and homogenous coating with biocompatibility and antimicrobial properties. The stability of AgZnHApCs suspensions was evaluated by ultrasound measurements. The value of stability parameters of AgZnHApCs suspension is in good agreement with the value of bidistilled water used as reference fluid. Homogeneously dispersed solutions of AgZnHApCs were synthesized to endeavor to optimize the physico-chemical and biological characteristics of the coatings obtained at room temperature. The AgZnHApCs composite suspension and coatings were analyzed using various investigation techniques, such as X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenylte-2H-tetrazolium bromide) assay and antimicrobial studies. The optical spectroscopy, atomic force microscopy (AFM), metallographic examination and X-ray photoelectron spectroscopy (XPS) on AgZnHApCs composite coatings were also conducted. Cell culture and MTT assays demonstrate that AgZnHApCs composite suspension and coatings have no negative effect on the cell viability and proliferation. The cell morphology was not affected in presence of AgZnHApCs composite suspension and coatings. The antimicrobial assays conducted againstStaphylococcus aureusATCC 25923,Escherichia coliATCC 25922, andCandida albicansATCC 90029 microbial strains revealed that both the AgZnHApCs composite suspension and coatings exhibited great antimicrobial properties.

44. Silver-Doped Hydroxyapatite Thin Layers Obtained by Sol-Gel Spin Coating Procedure

Authors: Prodan, AM; Iconaru, SL; Predoi, MV; Predoi, D; Motelica-Heino, M; Turculet, CS; Beuran, M

Published: JAN 2020, COATINGS, 10, DOI: 10.3390/coatings10010014

The main objective of this paper is to develop silver-doped hydroxyapatite suspensions (HApAg) with different concentrations of silver (x(Ag) = 0.05 and x(Ag) = 0.2) in order to obtain uniform and homogenous layers by spin-coating procedure. The colloidal properties of HApAg suspensions are evaluated by dynamic light scattering (DLS) analysis, zeta-potential (ZP), and ultrasound measurements. The ultrasound studies show that the HApAg20 sample revealed better stability than the HApAg5 sample. The structural and morphological analysis on suspensions and thin layers is also conducted. It is observed that the particles of the two samples have a similar shape and are uniform. The layers obtained present a homogeneous appearance of the surface without evidence of cracks or interruption of the coatings. The in vitro antifungal studies conducted on the two thin layers at two different time intervals (24 and 48 h) show that both HApAg5 (x(Ag) = 0.05) and HApAg20 (x(Ag) = 0.05) nanoparticles suspensions and composite layers inhibit the development of colony forming units (CFU) even after 24 h of incubation comparative to the control, represented by the Candida albicans (C. albicans) culture in a proper medium. The fungicidal effect was evident after 48 h of incubation in the case of both HApAg20 nanoparticles suspensions and composite layers.

45. Peppermint Essential Oil-Doped Hydroxyapatite Nanoparticles with Antimicrobial Properties

Authors: Badea, ML; Iconaru, SL; Groza, A; Chifiriuc, MC; Beuran, M; Predoi, D

Published: JUN 1 2019, MOLECULES, 24, DOI: 10.3390/molecules24112169

This study aimed at developing an antimicrobial material based on hydroxyapatite (HAp) and peppermint essential oil (P-EO) in order to stimulate the antimicrobial activity of hydroxyapatite. The molecular spectral features and morphology of the P-EO, HAp and hydroxyapatite coated with peppermint essential oil (HAp-P) were analyzed using Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The coating of the HAp with the P-EO did not affect the ellipsoidal shape of the nanoparticles. The overlapping of IR bands of P-EO and HAp in the HAp-P spectrum determined the formation of the broad molecular bands that were observed in the spectral regions of 400-1000 cm(-1) and 1000-1200 cm(-1). The antibacterial activity of the P-EO, HAp and HAp-P were also tested against different Gram-positive bacteria (methicillin-resistant Staphylococcus aureus (MRSA) 388, S. aureus ATCC 25923, S. aureus ATCC 6538, E. faecium DSM 13590), Gram-negative bacteria (Escherichia coli ATCC 25922, E. coli C5, P. aeruginosa ATCC 27853, P. aeruginosa ATCC 9027) and a fungal strain of Candida parapsilosis. The results of the present study revealed that the antimicrobial activity of HAp-P increased significantly over that of HAp.

46. The Effect of the Ionizing Radiation on Hydroxyapatite-Polydimethylsiloxane Layers

Authors: Groza, A; Iconaru, SL; Jiga, G; Chapon, P; Gaiaschi, S; Verga, N; Beuran, M; Prodan, AM; Matei, M; Marinescu, SA; Trusca, R; Predoi, D

Published: DEC 2019, POLYMER ENGINEERING AND SCIENCE, 59, 2412, DOI: 10.1002/pen.25247

The bio hydroxyapatite (HAp) was used from a long time in different medical and environmental applications. The HAp layers with a uniform surface were used for various medical applications such as orthopedic and dental metal implants. In this work, we reported on the influence of X-ray radiation on the structural and morphological properties of composite layers based on HAp and polydimethylsiloxane (PDMS) deposited on titanium substrates. The HAp:PDMS layers were investigated by different complementary methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and glow discharge optical emission spectrometry (GDOES). FTIR spectral analysis showed that the molecular structure of the coatings was not changed after their irradiation even though, the depth profile analysis performed by GDOES indicated a depletion of Ca and P elements from the HAp:PDMS irradiated samples. By SEM, we showed that the morphological features of the coatings were also changed, as the irradiated layers are delaminated. The biological assays confirmed that the antibacterial activity of HAp:PDMS composite layers increased after irradiation. The results obtained in this study highlighted that the biological properties of HAp:PDMS layers could be influenced by irradiation. (C) 2019 Society of Plastics Engineers.

47. Preparations of Silver/Montmorillonite Biocomposite Multilayers and Their Antifungal Activity

Authors: Iconaru, SL; Groza, A; Stan, GE; Predoi, D; Gaiaschi, S; Trusca, R; Chifiriuc, CM; Marutescu, L; Tite, T; Stanciu, GA; Hristu, R; Ghegoiu, L; Badea, ML; Turculet, CS; Ganciu, M; Chapon, P

Published: DEC 2019, COATINGS, 9, DOI: 10.3390/coatings9120817

In this study, the results about the influence of the surface morphology of layers based on montmorillonite (MMT) and silver (Ag) on antimicrobial properties are reported. The coating depositions were performed in the plasma of a radio frequency (RF) magnetron sputtering discharge. The studied layers were single montmorillonite layers (MMT) and silver/montmorillonite multilayers (MMT-Ag) obtained by magnetron sputtering technique with a different surface thickness. The resultant MMT-Ag biocomposite multilayers exhibited a uniform distribution of constituent elements and enhanced antimicrobial properties against fungal biofilm development. Glow-discharge optical emission spectroscopy (GDOES) analysis revealed the formation of MMT-Ag biocomposite multilayers following the deposit of a silver layer for an MMT layer that was initially deposited on a Si substrate. The surface morphology and thickness evaluation of deposited biocomposite layers were performed by scanning electron microscopy (SEM). A qualitative analysis of the chemical composition of thin layers was performed and the elements O, Ag, Mg, Fe, Al, and Si were identified in the MMT-Ag biocomposite multilayers. The in vitro antifungal assay proved that the inhibitory effect against the growth of Candida albicans ATCC 101231 CFU was more emphasized in the case of MMT-Ag biocomposite multilayers that in the case of the MMT layer. Cytotoxicity studies performed on HeLa cells showed that the tested layers did not show significant toxicity at the time intervals during which the assay was performed. On the other hand, it was observed that the MMT layers exhibited slightly higher biocompatible properties than the MMT-Ag composite layers.

48. Biocompatible Layers Obtained from Functionalized Iron Oxide Nanoparticles in Suspension

Authors: Predoi, D; Iconaru, SL; Predoi, MV; Buton, N; Megier, C; Motelica-Heino, M

Published: DEC 2019, COATINGS, 9, DOI: 10.3390/coatings9120773

Iron oxide nanoparticles have been extensively studied for challenges in applicable areas such as medicine, pharmacy, and the environment. The functionalization of iron oxide nanoparticles with dextran opens new prospects for application. Suspension characterization methods such as dynamic light scattering (DLS) and zeta potential (ZP) have allowed us to obtain information regarding the stability and hydrodynamic diameter of these suspended particles. For rigorous characterization of the suspension of dextran-coated iron oxide nanoparticles (D-MNPs), studies have been performed using ultrasound measurements. The results obtained from DLS and ZP studies were compared with those obtained from ultrasound measurements. The obtained results show a good stability of D-MNPs. A comparison between the D-MNP dimension obtained from transmission electron microscopy (TEM), X-ray diffraction (XRD), and DLS studies was also performed. A scanning electron spectroscopy (SEM) image of a surface D-MNP layer obtained from the stable suspension shows that the particles are spherical in shape. The topographies of the elemental maps of the D-MNP layer showed a uniform distribution of the constituent elements. The homogeneity of the layer was also observed. The morphology of the HeLa cells incubated for 24 and 48 h with the D-MNP suspension and D-MNP layers did not change relative to the morphology presented by the control cells. The cytotoxicity studies conducted at different time intervals have shown that a slight decrease in the HeLa cell viability after 48 h of incubation for both samples was observed.

49. Photoluminescent Hydroxylapatite: Eu3+ Doping Effect on Biological Behaviour

Authors: Andronescu, E; Predoi, D; Neacsu, IA; Paduraru, AV; Musuc, AM; Trusca, R; Oprea, O; Tanasa, E; Vasile, OR; Nicoara, AI; Surdu, AV; Iordache, F; Birca, AC; Iconaru, SL; Vasile, BS

Published: SEP 2019, NANOMATERIALS, 9, DOI: 10.3390/nano9091187

Luminescent europium-doped hydroxylapatite (Eu(X)HAp) nanomaterials were successfully obtained by co-precipitation method at low temperature. The morphological, structural and optical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), UV-Vis and photoluminescence (PL) spectroscopy. The cytotoxicity and biocompatibility of Eu(X)HAp were also evaluated using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)) assay, oxidative stress assessment and fluorescent microscopy. The results reveal that the Eu3+ has successfully doped the hexagonal lattice of hydroxylapatite. By enhancing the optical features, these Eu(X)HAp materials demonstrated superior efficiency to become fluorescent labelling materials for bioimaging applications.

50. Synthesis, Characterization, and Antimicrobial Activity of Magnesium-Doped Hydroxyapatite Suspensions

Authors: Predoi, D; Iconaru, SL; Predoi, MV; Stan, GE; Buton, N

Published: SEP 2019, NANOMATERIALS, 9, DOI: 10.3390/nano9091295

Obtaining nanoscale materials has allowed for the miniaturization of components, which has led to the possibility of achieving more efficient devices with faster functions and much lower costs. While hydroxyapatite [HAp, Ca-10(PO4)(6)(OH)(2)] is considered the most widely used material for medical applications in orthopedics, dentistry, and general surgery, the magnesium (Mg) is viewed as a promising biodegradable and biocompatible implant material. Furthermore, Mg is regarded as a strong candidate for developing medical implants due to its biocompatibility and antimicrobial properties against gram-positive and gram-negative bacteria. For this study, magnesium-doped hydroxyapatite (Ca10-xMgx (PO4)(6) (OH)(2), x(Mg) = 0.1), 10MgHAp, suspensions were successfully obtained by an adapted and simple chemical co-precipitation method. The information regarding the stability of the nanosized 10MgHAp particles suspension obtained by zeta-potential analysis were confirmed for the first time by a non-destructive ultrasound-based technique. Structural and morphological studies of synthesized 10MgHAp were conducted by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy in attenuated total reflectance (ATR) mode and scanning electron microscopy (SEM). The XRD analysis of the 10MgHAp samples confirmed that a single crystalline phase associated to HAp with an average grain size about 93.3 nm was obtained. The FTIR-ATR spectra revealed that the 10MgHAp sample presented broader IR bands with less visible peaks when compared to a well-crystallized pure HAp. The SEM results evidenced uniform MgHAp nanoparticles with spherical shape. The antimicrobial activity of the 10MgHAp suspension against gram-positive strains (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212), gram-negative strains (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853), as well as a fungal strain (Candida albicans ATCC 90029) were evaluated.

51. Zinc Doped Hydroxyapatite Thin Films Prepared by Sol-Gel Spin Coating Procedure

Authors: Predoi, D; Iconaru, SL; Predoi, MV; Buton, N; Motelica-Heino, M

Published: FEB 28 2019, COATINGS, 9, DOI: 10.3390/coatings9030156

In this study, ZnHAp layers deposited on a Si substrate were obtained by a sol-gel spin-coating procedure. The ZnHAp solutions used to obtain the ZnHAp coatings were investigated by dynamic light scattering (DLS) analysis, zeta-potential, ultrasound measurements, and flame atomic absorption spectrometry (AAS). The average measured hydrodynamic diameter from the DLS analysis, zeta-potential, and ultrasound measurements were analyzed so as to characterize and estimate the stability of the ZnHAp nanoparticles. The AAS results confirmed the presence of zinc in the gels used in the preparation of the ZnHAp layers. The layers were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results revealed the diffraction peaks of the hexagonal hydroxyapatite in all of the investigated samples. The morphology of the ZnHAp coatings annealed at 500 degrees C (ZnHAp-500) and 700 degrees C (ZnHAp-700), which evidenced that no fissures or cracks formed on the surface of the coatings. The biocompatibility assays indicated that the ZnHAp coatings did not present any toxicity towards the HeLa cells. Furthermore, the study regarding the cytotoxicity of the ZnHAp layers against microorganisms emphasized that ZnHAp coatings exhibited an inhibitory effect towards S. aureus bacterial cells and also towards C. albicans fungal cells.

52. Evaluation of Antibacterial Activity of Zinc-Doped Hydroxyapatite Colloids and Dispersion Stability Using Ultrasounds

Authors: Predoi, D; Iconaru, SL; Predoi, MV; Motelica-Heino, M; Guegan, R; Buton, N

Published: APR 2019, NANOMATERIALS, 9, DOI: 10.3390/nano9040515

This study proves that the new developed zinc-doped hydroxyapatite (ZnHAp) colloids by an adapted sol-gel method can be widely used in the pharmaceutical, medical, and environmental industries. ZnHAp nanoparticles were stabilized in an aqueous solution, and their colloidal dispersions have been characterized by different techniques. Scanning Electron Microscopy (SEM) was used to get information on the morphology and composition of the investigated samples. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the elemental compositions of ZnHAp colloidal dispersions. The homogeneous and uniform distribution of constituent elements (zinc, calcium, phosphorus, oxygen) was highlighted by the obtained elemental mapping results. The X-ray diffraction (XRD) results of the obtained samples showed a single phase corresponding to the hexagonal hydroxyapatite. The characteristic bands of the hydroxyapatite structure were also evidenced by Fourier-transform infrared spectroscopy (FTIR) analysis. For a stability assessment of the colloidal system, -potential for the ZnHAp dispersions was estimated. Dynamic light scattering (DLS) was used to determine particles dispersion and hydrodynamic diameter (D-HYD). The goal of this study was to provide for the first time information on the stability of ZnHAp particles in solutions evaluated by non-destructive ultrasound-based technique. In this work, the influence of the ZnHAp colloidal solutions stability on the development of bacteria, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), was also established for the first time. The antimicrobial activity of ZnHAp solutions was strongly influenced by both the stability of the solutions and the amount of Zn.

53. Dextran-Coated Zinc-Doped Hydroxyapatite for Biomedical Applications

Authors: Predoi, D; Iconaru, SL; Predoi, MV

Published: MAY 2019, POLYMERS, 11, DOI: 10.3390/polym11050886

Dextran-coated zinc-doped hydroxyapatite (ZnHApD) was synthesized by an adapted sol-gel method. The stability of ZnHApD nanoparticles in an aqueous solution was analyzed using ultrasonic measurements. The analysis of the evolution in time of the attenuation for each of the frequencies was performed. The X-ray diffraction (XRD) investigations exhibited that no impurity was found. The morphology, size and size distribution of the ZnHApD sample was investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The TEM and SEM results showed that the ZnHApD particles have an ellipsoidal shape and a narrow distribution of sizes. The cell growth and toxicity of HEK-293 cells were investigated on the ZnHApD solution for four different concentrations and analyzed after 24 and 48 h. The ZnHApD solution presented a non-toxic activity against HEK-293 cells for all analyzed concentrations. The antibacterial assay revealed that all the tested microorganisms were inhibited by the ZnHApD dispersion after 24 and 48 h of incubation. It was observed that the effect of the ZnHApD solution on bacteria growth depended on the bacterial strain. The Porphyromonas gingivalis ATCC 33277 bacterial strain was the most sensitive, as a growth inhibition in the presence of 0.075 mu g/mL ZnHApD in the culture medium was observed.

54. Study of the Structure and Antimicrobial Activity of Ca-Deficient Ceramics on Chlorhexidine Nanoclay Substrate

Authors: Pazourkova, L; Reli, M; Hundakova, M; Pazdziora, E; Predoi, D; Martynkova, GS; Lafdi, K

Published: SEP 2019, MATERIALS, 12, DOI: 10.3390/ma12182996

Novel biomedical composites, based on organically modified vermiculite and montmorillonite with deposited Ca-deficient hydroxyapatite (CDH), were prepared. The monoionic sodium forms of vermiculite and montmorillonite were intercalated with chlorhexidine diacetate (CA). The surfaces of organoclays were used for the precipitation of Ca-deficient hydroxyapatite. The composites with Ca-deficient hydroxyapatite showed very good antibacterial effects, similar to the antimicrobial activity of pure organoclay samples. Better antibacterial activity was shown in the organically modified montmorillonite sample with Ca-deficient hydroxyapatite compared with the vermiculite composite, but, in the case of Staphylococcus aureus, both composites showed the same minimum inhibitory concentration (MIC) value. The antimicrobial effect of composites against bacteria and fungi increased with the time of exposure. The structural characterization of all the prepared materials, performed using X-ray diffraction and FT infrared spectroscopy analysis, detected no changes in the original clay or CDH during the intercalation or precipitation process, therefore we expect the strength of the compounds to be in the original power.

55. Commercial Hydroxyapatite Powders for Lead Removal from Aqueous Solution

Authors: Negrila, CC; Iconaru, SL; Motelica-Heino, M; Guegan, R; Predoi, G; Barbuceanu, F; Ghita, RV; Petre, CC; Jiga, G; Badea, ML; Prodan, AM; Predoi, D

Published: 2018, 9TH INTERNATIONAL CONFERENCE ON TIMES OF POLYMERS AND COMPOSITES: FROM AEROSPACE TO NANOTECHNOLOGY, 1981, DOI: 10.1063/1.5045983

Nowadays, the advances materials science have created the possibility of using nanomaterials as adsorbents in environmental technologies. This study is focused on the evaluation of C-HAp powders capacity in lead ions removal from contaminated solutions. The C-HAp powders after removal of lead (Pb2+) ions from contaminated water were characterized by X-Ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray analysis (EDX). The presence of lead in the hydroxyapatite powders after removal experiments was observed in the XPS general spectrum and also in the EDX spectra. In addition, the AAS studies revealed that the C-HAp powders possess a high affinity towards lead ions with an effective removal rate of 80% for an initial lead concentration of 20 mg.L-1.

56. Antimicrobial Studies on Iron Oxide-Dextran Colloidal Suspension

Authors: Predoi, D; Iconaru, SL; Buton, N; Predoi, G; Barbuceanu, F; Petre, CC; Jiga, G; Badea, ML; Prodan, AM

Published: 2018, 9TH INTERNATIONAL CONFERENCE ON TIMES OF POLYMERS AND COMPOSITES: FROM AEROSPACE TO NANOTECHNOLOGY, 1981, DOI: 10.1063/1.5045967

Iron oxide-dextran nanoparticle suspensions (IOD-NPsS) have attracted attention for their considerable applications in various biomedical area such as cosmetics, water remediation, hyperthermia, drug delivery or magnetic resonance imaging (MRI) contrast enhancement. In these research we report the antimicrobial studies on iron oxide-dextran colloidal suspension against prokaryotic cells such as Escherichia coli (E. coli). The ultrasound studies and dynamic light scattering (DLS) of iron oxide-dextran nanoparticle suspensions. According colloidal studies of the iron oxide suspension, the nanoparticles was in dispersed state.

57. Physico-Chemical Characteristics and Antimicrobial Studies of Silver Doped Hydroxyapatite

Authors: Predoi, D; Predoi, MV; El Kettani, MEC; Leduc, D; Iconaru, SL; Ciobanu, CS; Buton, N; Petre, CC; Prodan, AM

Published: 2018, 7TH INTERNATIONAL CONFERENCE ON STRUCTURAL ANALYSIS OF ADVANCED MATERIALS (ICSAAM 2017), 1932, DOI: 10.1063/1.5024184

The present research is focused on the synthesis, structural and morphological characterization and antimicrobial evaluation of silver doped hydroxyapatite (AgHAp) in water. The preliminary ultrasonic characterizations of the AgHAp in water synthesized by an adapted co-precipitation method are also presented. X-ray diffraction result showed that silver ions were substituted in the hydroxyapatite structure. The lattice parameters increased when the silver substitution increased. The morphology of AgHAp were evaluated by Scanning Electron Microscopy (SEM). By EDX analysis the constituents elements of hydroxyapatite were detected in all analyzed samples. The silver was also found in the samples with x(Ag) = 0.5 and 0.2. The colloidal properties of the resulted AgHAp (x(Ag) = 0.0, 0.05 and 0.2) in water were analyzed by Dynamic Light Scattering (DLS) and zeta potential. On the other hand, the novelty of our research consists of preliminary ultrasonic measurements (US) conducted on AgHAp in water. Furthermore, the antimicrobial activity of AgHAp was evaluated and a decrease in the number of surviving cells was established.

58. Properties of Basil and Lavender Essential Oils Adsorbed on the Surface of Hydroxyapatite

Authors: Predoi, D; Groza, A; Iconaru, SL; Predoi, G; Barbuceanu, F; Guegan, R; Motelica-Heino, MS; Cimpeanu, C

Published: MAY 2018, MATERIALS, 11, DOI: 10.3390/ma11050652

The research conducted in this study presented for the first time results of physico-chemical properties and in vitro antimicrobial activity of hydroxyapatite plant essential oil against Gram-positive bacteria (methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus 0364) and Gram-negative bacteria (Escherichia coli ATCC 25922). The samples were studied by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy to determine the morphology and structure of the nanocomposites of hydroxyapatite coated with basil (HAp-B) and lavender (HAp-L) essential oils (EOs). The values of the BET specific surface area (S-BET), total pore volume (V-P) and pore size (D-P) were determined. The results for the physico-chemical properties of HAp-L and HAp-B revealed that lavender EOs were well adsorbed on the surface of hydroxyapatite, whereas basil EOs showed a poor adsorption on the surface of hydroxyapatite. We found that the lavender EOs hydroxyapatite (HAp-L) exhibited a very good inhibitory growth activity. The value of the minimum inhibitory concentration (MIC) related to growth bacteria was 0.039 mg/mL for MRSA, 0.02 mg/mL for S. aureus and 0.039 mg/mL E. coli ATCC 25922. The basil EO hydroxyapatite (HAp-B) showed poor inhibition of bacterial cell growth. The MIC value was 0.625 mg/mL for the HAp-B sample in the presence of the MRSA bacteria, 0.313 mg/mL in the presence of S. aureus and 0.078 mg/mL for E. coli ATCC 25922.

59. Bioceramic Layers with Antifungal Properties

Authors: Predoi, D; Iconaru, SL; Predoi, MV

Published: AUG 2018, COATINGS, 8, DOI: 10.3390/coatings8080276

The sol-gel method was used to synthesize the silver doped hydroxyapatite (Ag:HAp) gels in order to produce the antifungal composite layers. The pure Ti disks were used as the substrate for the composite layers. Important information about suspensions used to make Ag:HAp composite layers were obtained from an ultrasonic technique. The identification of the phase composition of the Ag:HAp composite layers was accomplished X-ray diffraction (XRD). The morphology and the thickness of the layers was evaluated using scanning electron microscopy (SEM). The uniform distribution of the constituent elements (Ag, Ca, P, and O) in both analyzed samples was observed. The antifungal activity of the samples against Candida albicans ATCC 10231 microbial strain were investigated immediately after their preparation and six months later. SEM and confocal laser scanning microscopy (CLSM) images showed that the composite layers at the two time intervals exhibited a strong antifungal activity against Candida albicans ATCC 10231 and completely inhibited the biofilm formation.

60. Removal of Zinc Ions Using Hydroxyapatite and Study of Ultrasound Behavior of Aqueous Media

Authors: Iconaru, SL; Motelica-Heino, M; Guegan, R; Predoi, MV; Prodan, AM; Predoi, D

Published: AUG 2018, MATERIALS, 11, DOI: 10.3390/ma11081350

The present study demonstrates the effectiveness of hydroxyapatite nanopowders in the adsorption of zinc in aqueous solutions. The synthesized hydroxyapatites before (HAp) and after the adsorption of zinc (at a concentration of 50 mg/L) in solution (HApD) were characterized using X-ray diffraction (XRD), and scanning and transmission electron microscopy (SEM and TEM, respectively). The effectiveness of hydroxyapatite nanopowders in the adsorption of zinc in aqueous solutions was stressed out through ultrasonic measurements. Both Langmuir and Freundlich models properly fitted on a wide range of concentration the equilibrium adsorption isotherms, allowing us to precisely quantify the affinity of zinc to hydroxyapatite nanopowders and to probe the efficacy of hydroxyapatite in removal of zinc ions from aqueous solutions in ultrasonic conditions.

61. Influence of Ionizing Radiations on Structural and Antibacterial Properties of Hydroxyapatite-Polydimethylsiloxane Layers

Authors: Groza, A; Iconaru, SL; Petre, CC; Jiga, G; Badea, ML; Prodan, AM; Beuran, M; Chapon, P; Gaianschi, S; Ganciu, M; Verga, N; Trusca, R; Vineticu, N; Predoi, D

Published: 2018, 9TH INTERNATIONAL CONFERENCE ON TIMES OF POLYMERS AND COMPOSITES: FROM AEROSPACE TO NANOTECHNOLOGY, 1981, DOI: 10.1063/1.5045985

In the recent years a special attention has been granted to the generation and characterization of hydroxyapatite-polydimethylsiloxane layers especially due to their biomedical applications. In this context, in this paper, we analyzed the influence of X ray radiation delivered in medical dose on the morphological mid chemical structure of hydroxyapatite-polydimethylsiloxane layers deposited on Ti substrates. The damage effects produced by the ionizing radiation on the surface and structure of hydroxyapatite-polydimethylsiloxane layers were identified by Scanning Electron Microscopy (SEM) and Glow Discharge Optical Emission Spectroscopy (GDOES). The antibacterial activity of the irradiated and non irradiated samples was also evaluated.

62. Application of Biocompatible Magnetite Nanoparticles for the Removal of Arsenic and Copper from Water

Authors: Iconaru, SL; Beuran, M; Turculet, CS; Negoi, I; Teleanu, G; Prodan, AM; Motelica-Heino, M; Guegan, R; Ciobanu, CS; Jiga, G; Predoi, D

Published: 2018, 7TH INTERNATIONAL CONFERENCE ON STRUCTURAL ANALYSIS OF ADVANCED MATERIALS (ICSAAM 2017), 1932, DOI: 10.1063/1.5024168

The progress of nanotechnology made possible the use of nanomaterials as adsorbents and magnetic iron oxides represents one of the first generations of nanoscale materials used in environment technologies [1]. A systematic characterization of commercial magnetite (Fe3O4) is presented in this research. The commercial (Fe3O4) magnetic adsorbents were characterized by various characterizations methods such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDX). This study was also focused on the study of adsorption isotherms and the kinetics evaluation. X-ray studies indicated that As3+ and Cu2+ removed by Fe3O4 did not seem to alter the structure of Fe3O4 but they were highlighted in the EDX analysis. In addition, the SEM studies were consistent with the XRD results. The rate of adsorption of contaminants, in contaminated solutions decreases when the amount of contaminant increases in all experiments performed. The results revealed that Fe3O4 nanoparticles are promising candidates which could be used as sorbents for the removal of arsenic from the marine environment, for site remediation and groundwater treatment.

63. Adsorption of Pb (II) Ions onto Hydroxyapatite Nanopowders in Aqueous Solutions

Authors: Iconaru, SL; Motelica-Heino, M; Guegan, R; Beuran, M; Costescu, A; Predoi, D

Published: NOV 2018, MATERIALS, 11, DOI: 10.3390/ma11112204

Contamination of water with heavy metals such as lead is a major worldwide problem because they affect the physiological functions of living organisms, cause cancer, and damage the immune system. Hydroxyapatite, (Ca-5(PO4)(3)OH) is considered one of the most effective materials for removing heavy metals from contaminated water. The hydroxyapatite nanopowders (N-HAp) obtained by a co-precipitation method were used in this research to determine the effectiveness in removing lead ions from contaminated solutions. In this study, we have investigated the structure and morphology of N-HAp nanopowders using X-ray diffraction (XRD), electronic transmission microscopy (TEM), and scanning electron microscopy (SEM). The structure information was also obtained by spectroscopy measurements. The Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy measurements revealed the presence of peaks corresponding to the phosphate and hydroxyl groups. The ability of N-HAp nanopowders to adsorb lead ions from aqueous solutions were established. The results of the kinetic and equilibrium studies on the removal of Pb (II) from aqueous solution revealed that the adsorption of lead (II) cations is due to the surface reaction with the hydroxyl terminal groups on the adsorbent and the combination of the positive charges of the metal cations with the negative charges on the adsorbent surfaces. These observations could validate the use of these ceramic nanopowders in ecological remediation strategies.

64. Antimicrobial Activity of New Materials Based on Lavender and Basil Essential Oils and Hydroxyapatite

Authors: Predoi, D; Iconaru, SL; Buton, N; Badea, ML; Marutescu, L

Published: MAY 2018, NANOMATERIALS, 8, DOI: 10.3390/nano8050291

This study presents, for the first-time, the results of a study on the hydrodynamic diameter of essential oils (EOs) of basil and lavender in water, and solutions of EOs of basil (B) and lavender (L) and hydroxyapatite (HAp). The possible influence of basil and lavender EOs on the size of hydroxyapatite nanoparticles was analyzed by Scanning Electron Microscopy (SEM). We also investigated the in vitro antimicrobial activity of plant EOs and plant EOs hydroxyapatite respectively, against Gram-positive bacteria (methicillin-resistant Staphylococcus aureus1144 (MRSA 1144) and S. aureus 1426) and Gram-negative bacteria (Escherichia coli ATCC 25922 and Escherichia coli ESBL 4493). From the autocorrelation function, obtained by Dynamic Light Scattering (DLS) measurements it was observed that basil yielded one peak at an average hydrodynamic diameter of 354.16 nm, while lavender yielded one peak at an average hydrodynamic diameter of 259.76 nm. In the case of HAp nanoparticles coated with basil (HApB) and lavender (HApL) essential oil, the aggregation was minimal. We found that the lavender EO exhibited a very good inhibitory growth activity (MIC values ranging from <0.1% for E. coli reference strain to 0.78% for S. aureus strains). The biological studies indicated that HapL material displayed an enhanced antimicrobial activity, indicating the potential use of HAp as vehicle for low concentrations of lavender EO with antibacterial properties. Flow cytometry analysis (FCM) allowed us to determine some of the potential mechanisms of the antimicrobial activities of EOs, suggesting that lavender EO was active against E. coli by interfering with membrane potential, the membrane depolarization effect being increased by incorporation of the EOs into the microporous structure of HAp. These findings could contribute to the development of new antimicrobial agents that are urgently needed for combating the antibiotic resistance phenomena.

65. Development of Zinc-Doped Hydroxyapatite by Sol-Gel Method for Medical Applications

Authors: Negrila, CC; Predoi, MV; Iconaru, SL; Predoi, D

Published: NOV 2018, MOLECULES, 23, DOI: 10.3390/molecules23112986

Zinc- (Zn) doped hydroxyapatite (HAp) were prepared by sol-gel method. Zinc-doped hydroxyapatite (ZnHAp) and HAp were analyzed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The Rietveld analysis revealed that the HAp and 7ZnHAp powders obtained by sol-gel method have a monophasic hydroxyapatite structure belonging to the P6(3/m) spatial group. The results obtained from the ultrasound characterization of HAp and ZnHAp are also presented in this study. The effect of zinc concentration on properties that were deduced from ultrasonic measurements are studied in the case of a significant zinc concentration (x(Zn) = 0.07). From the values of the ultrasonic waves velocities were determined by the pairs of elastic coefficients of the suspensions (Young modulus E, Poisson coefficient nu), which have proven to be similar to those determined by other authors.

66. ANALYSIS of Pdge-BASED CONTACT on N-Gasb

Authors: Ghita, RV; Negrila, CC; Predoi, D; Trusca, R

Published: 2018, 7TH INTERNATIONAL CONFERENCE ON STRUCTURAL ANALYSIS OF ADVANCED MATERIALS (ICSAAM 2017), 1932, DOI: 10.1063/1.5024167

Pd-Ge based ohmic contacts on III-V semiconductor e.g.Pd-Ge on n-GaAs are viewed as a viable alternative to low contact resistance metallization. As it was remarked [11, together with the device dimensions decrease, the AuGeNi metallization system becomes inadequate for shallow-junction devices. This characteristic is related to the formation of a low melting point beta- AuGa phase that leads to a poor contact thermal stability. Gallium Antimonide is anIII-V semiconductor compound that can be used in a photovoltaic convertor of GaAs/GaSb tandem stack With a predicted efficiency of 30%. Reduced series resistance on GaSb cells can be achieved by the improving of contact metallization properties. The present study is dedicated to the preparation conditions and structural analyzing of PdGe based contacts on n-GaSb, namely: Pd/Au/Ge. There are presented the depth profiling for PdGe metallization obtained from XPS measurements, and morphologic studies arisen from SEM technique and AFM technique.

67. ZnHAp Thin Films for Medical Applications

Authors: Iconaru, SL; Groza, A; Chapon, P; Gaianschi, S; Petre, CC; Jiga, G; Beuran, M; Prodan, AM; Lupescu, O; Trusca, R; Predoi, D

Published: 2018, 9TH INTERNATIONAL CONFERENCE ON TIMES OF POLYMERS AND COMPOSITES: FROM AEROSPACE TO NANOTECHNOLOGY, 1981, DOI: 10.1063/1.5045984

The research regarding the properties of thin films of hydroxyapatite doped with various ions such as zinc elaborated by spin-coating technique have rarely been fabricated and studies in recent years. In the present study Zn doped hydroxyapatite (ZrHAp) synthesized by a sol-gel method were coated on Ti substrates using a spin-coating technique. The thin films was characterized by Scanning Electron Microscopy (SEM) and Glow Discharge Optical Emission Spectroscopy (GDOES). The structural characterizations of ZnHAp thin films showed the presence of Zn and apatitic structure. The GD depth profiles revealed the successful embedding of the Zn ions in HAp structure. In addition, in vitro evaluation of the antifungal properties of ZnHAp demonstrated the potential antifungal effect of ZnHAp thin films against Staphylococcus aureus 0364 biofilm.

68. Structural Characterization and Antifungal Studies of Zinc-Doped Hydroxyapatite Coatings

Authors: Iconaru, SL; Prodan, AM; Buton, N; Predoi, D

Published: APR 2017, MOLECULES, 22, DOI: 10.3390/molecules22040604

The present study is focused on the synthesis, characterization and antifungal evaluation of zinc-doped hydroxyapatite (Zn:HAp) coatings. The Zn:HAp coatings were deposited on a pure Si (Zn:HAp_Si) and Ti (Zn:HAp_Ti) substrate by a sol-gel dip coating method using a zinc-doped hydroxyapatite nanogel. The nature of the crystal phase was determined by X-ray diffraction (XRD). The crystalline phase of the prepared Zn:HAp composite was assigned to hexagonal hydroxyapatite in the P6(3/m) space group. The colloidal properties of the resulting Zn:HAp (x(Zn) = 0.1) nanogel were analyzed by Dynamic Light Scattering (DLS) and zeta potential. Scanning Electron Microscopy (SEM) was used to investigate the morphology of the zinc-doped hydroxyapatite (Zn:HAp) nanogel composite and Zn:HAp coatings. The elements Ca, P, O and Zn were found in the Zn:HAp composite. According to the EDX results, the degree of Zn substitution in the structure of Zn:HAp composite was 1.67 wt%. Moreover, the antifungal activity of Zn:HAp_Si and Zn:HAp_Ti against Candida albicans (C. albicans) was evaluated. A decrease in the number of surviving cells was not observed under dark conditions, whereas under daylight and UV light illumination a major decrease in the number of surviving cells was observed.

69. Advances in Functionalized Materials Research 2016

Authors: Predoi, D; Motelica-Heino, M; Guegan, R; Le Coustumer, P

Published: 2017, JOURNAL OF NANOMATERIALS, 2017, DOI: 10.1155/2017/1269319

70. Textural, Structural and Biological Evaluation of Hydroxyapatite Doped with Zinc at Low Concentrations

Authors: Predoi, D; Iconaru, SL; Deniaud, A; Chevallet, M; Michaud-Soret, I; Buton, N; Prodan, AM

Published: MAR 2017, MATERIALS, 10, DOI: 10.3390/ma10030229

The present work was focused on the synthesis and characterization of hydroxyapatite doped with low concentrations of zinc (Zn: HAp) (0.01 < x(Zn) < 0.05). The incorporation of low concentrations of Zn2+ ions in the hydroxyapatite (HAp) structure was achieved by co-precipitation method. The physico-chemical properties of the samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy (SEM), zeta-potential, and DLS and N2-BET measurements. The results obtained by XRD and FTIR studies demonstrated that doping hydroxyapatite with low concentrations of zinc leads to the formation of a hexagonal structure with lattice parameters characteristic to hydroxyapatite. The XRD studies have also shown that the crystallite size and lattice parameters of the unit cell depend on the substitutions of Ca2+ with Zn2+ in the apatitic structure. Moreover, the FTIR analysis revealed that the water content increases with the increase of zinc concentration. Furthermore, the Energy Dispersive X-ray Analysis (EDAX) and XPS analyses showed that the elements Ca, P, O, and Zn were found in all the Zn: HAp samples suggesting that the synthesized materials were zinc doped hydroxyapatite, Ca10-Zn-x(x)(PO4) (6)(OH), with 0.01 <= x(Zn) <= 0.05. Antimicrobial assays on Staphylococcus aureus and Escherichia coli bacterial strains and HepG2 cell viability assay were carried out.

71. Ultrasound studies on magnetic fluids based on maghemite nanoparticles

Authors: Predoi, D; Popa, CL; Predoi, MV

Published: JUN 2017, POLYMER ENGINEERING AND SCIENCE, 57, 490, DOI: 10.1002/pen.24501

In the last decades, the study of magnetic fluids with different biomedical applications such as targeted delivery of a chemotherapeutic solution to the tumor site has been of high interest. For this purpose, ultrasonic and antimicrobial studies were used to characterize the aqueous solutions based on maghemite nanoparticles. The maghemite (-Fe2O3) and dextran-coated maghemite nanoparticles (DMNp) were synthesized by coprecipitation method. The spherical shape of the nanoparticles and uniform size with an average diameter around 9.5 +/- 0.5nm for -Fe2O3 were observed in transmission electron microscopy micrographs. Dynamic light scattering was used to determine the hydrodynamic size of -Fe2O3 nanoparticles and DMNp in suspensions. The hydrodynamic diameter obtained of -Fe2O3 and DMNp was 17 and 21nm, respectively. Moreover, a noninvasive method based on ultrasounds was used to characterize the aqueous solutions. The preliminary results showed the attainable accuracy in determining acoustic wave velocity and attenuation in various solutions. These data could be correlated with particle density and size. More than that, velocity and attenuation can be used as characteristic parameters of a given solution. A finite element model of the dispersed particles, correlated with measured velocity, allowed to solve for the elastic properties of the particles. POLYM. ENG. SCI., 57:485-490, 2017. (c) 2017 Society of Plastics Engineers

72. Ultrasonic Measurements on Cyclodextrin/Hydroxyapatite Composites for Potential Water Depollution

Authors: Predoi, D; Predoi, MV; Iconaru, SL; El Kettani, MEC; Leduc, D; Prodan, AM

Published: JUN 2017, MATERIALS, 10, DOI: 10.3390/ma10060681

This paper presents structural, morphological and preliminary ultrasonic characterizations of the -Cyclodextrin/hydroxyapatite (CD-HAp) composites synthesized by an adapted co-precipitation method. The structural and morphological properties were evaluated by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). The specific surface area, pore size and pore volume were determined using the methods of Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH), respectively. The novelty of our study consists in preliminary ultrasonic measurements conducted on CD-HAp composite, uniformly dispersed in distilled water. The benefit of this non-destructive method was to facilitate and simplify the characterization techniques of nanoparticles. Our experiments proved that the efficiency of lead ion removal by CD-HAp composites depended on the initial concentration of lead. The maximum adsorption capacity of the solid phase, for Pb2+ indicated a higher rate of removal by the CD-HAp_2. These adsorption results bring valuable insight into the beneficial contribution of our compounds, for the removal of heavy metal ions from aqueous solutions. Furthermore, in the present study, was evaluated the toxic effect of lead ions adsorbed by hydroxyapatite from contaminated water on HeLa cells.

73. Physicochemical and antimicrobial properties of silver-doped hydroxyapatite collagen biocomposite

Authors: Predoi, D; Iconaru, SL; Albu, M; Petre, CC; Jiga, G

Published: JUN 2017, POLYMER ENGINEERING AND SCIENCE, 57, 545, DOI: 10.1002/pen.24553

Silver-doped hydroxyapatite (AgHAp) was prepared by co-precipitation method at room temperature. The obtained AgHAp was added in different amounts of collagen gel (AgHApC1 and AgHApC2). Afterward, the gel was lyophilized and the final AgHApC1 and AgHApC2 composite was achieved. The purity, crystallinity, and the phase composition of the AgHAp, AgHApC1, and AgHApC2 samples were evaluated by X-ray diffraction (XRD). The planes corresponding to the 2 values for hydroxyapatite were found in the three samples analyzed in agreement with the crystalline hydroxyapatite. In the Fourier transform infrared (FT-IR) spectra of AgHApC1 and AgHApC2 samples the peak characteristic to the presence of (2) phosphate mode at 472/cm was found. The peaks resulting from the (4) vibration of the P-O mode, (1) symmetric P-O stretching vibration and (3) P-O stretching vibration of PO43- were also evidenced in all the samples. The formation of agglomerated particles with uniform particle size was evidenced by scanning electron microscope (SEM). The uniform distribution of the constituent elements was evidenced by mapping analysis. Furthermore, the strong antibacterial activity of AgHAp, AgHApC1, and AgHApC2 samples against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacterial strains was shown. The inhibition zone increased drastically with the increase of silver concentration. POLYM. ENG. SCI., 57:537-545, 2017. (c) 2017 Society of Plastics Engineers

74. Synthesis, Characterization, and Toxicity Evaluation of Dextran-Coated Iron Oxide Nanoparticles

Authors: Balas, M; Ciobanu, CS; Burtea, C; Stan, MS; Bezirtzoglou, E; Predoi, D; Dinischiotu, A

Published: FEB 2017, METALS, 7, DOI: 10.3390/met7020063

We report the synthesis of dextran-coated iron oxide magnetic nanoparticles (DIO-NPs) with spherical shape and uniform size distribution as well as their accumulation and toxic effects on Jurkat cells up to 72 h. The characterization of dextran-coated maghemite nanoparticles was done by X-ray diffraction and dynamic light scattering analyses, transmission electron microscopy imaging, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, magnetic hysteresis, and relaxometry measurements. The quantification of DIO-NPs intracellular uptake showed a progressive accumulation of iron as a function of time and dose accompanied by additional lysosome formation and an increasing darkening exhibited by a magnetic resonance imaging (MRI) scanner. The cytotoxicity assays revealed a decrease of cell viability and a loss of membrane integrity in a time-and dose-dependent manner. Exposure to DIO-NPs determined an increase in reactive oxygen species level up to 72 h. In the first two days of exposure, the level of reduced glutathione decreased and the amount of malondyaldehyde increased, but at the end of the experiment, their concentrations returned to control values. These nanoparticles could be used as contrast agents for MRI but several parameters concerning their interaction with the cells should be taken into consideration for a safe utilization.

75. The tolerability of dextran-coated iron oxide nanoparticles during in vivo observation of the rats

Authors: Popa, CL; Prodan, AM; Ciobanu, CS; Predoi, D

Published: JUL 2016, GENERAL PHYSIOLOGY AND BIOPHYSICS, 35, 310, DOI: 10.4149/gpb_2016004

Superparamagnetic iron oxide nanoparticles (SPION) have attracted a lot of interest due to their widespread biomedical and diagnostic applications. Coating the SPIONs with various surface layers can provide an interface between the core and the surrounding environment. The aim of this study was to examine the in vivo behaviour of dextran-coated iron oxide nanoparticles (D-IONPs) in aqueous suspensions. The SPIONs stabilized with dextran (D-IONPs) were synthesized in aqueous solutions by co-precipitation method. The average grain size deduced from transmission electron microscopy is 7.5 nm. The hematological parameters registered for the rats exposed to D-IONPs at 1 ml/kg have had values approximately equal to those examined for the control specimen. The architecture of liver and kidneys was not affected after one day of intraperitoneal injection of D-IONPs compared to the reference group. After 21 and 28 days respectively from the administration of the D-IONPs solution, the liver and kidneys from the injected rats showed a normal aspect without abnormalities compared to the rats uninjected. Our findings suggest that the administration of 1 ml/kg D-IONPs did not cause any toxicological effect since the parameters of renal and liver function were in the normal range as reported to the control group.

76. Structural and Biological Assessment of Zinc Doped Hydroxyapatite Nanoparticles

Authors: Popa, CL; Deniaud, A; Michaud-Soret, I; Guegan, R; Motelica-Heino, M; Predoi, D

Published: 2016, JOURNAL OF NANOMATERIALS, 2016, DOI: 10.1155/2016/1062878

The aim of the current research work was to study the physicochemical and biological properties of synthesized zinc doped hydroxyapatite (ZnHAp) nanoparticles with Zn concentrations x(Zn) = 0 (HAp), x(Zn) = 0.07 (7ZnHAp), and x(Zn) = 0.1 (10ZnHAp) for potential use in biological applications. The morphology, size, compositions, and incorporation of zinc into hydroxyapatite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Raman scattering, and X-Ray Photoelectron Spectroscopy (XPS). In addition, the cytotoxicity of ZnHAp nanoparticles was tested on both E. coli bacteria and human hepatocarcinoma cell line HepG2. The results showed that ZnHAp nanoparticles (HAp, 7ZnHAp, and 10ZnHAp) have slightly elongated morphologies with average diameters between 25 nm and 18 nm. On the other hand, a uniform and homogeneous distribution of the constituent elements (calcium, phosphorus, zinc, and oxygen) in the ZnHAp powder was noticed. Besides, FTIR and Raman analyses confirmed the proper hydroxyapatite structure of the synthesized ZnHAp nanoparticles with the signature of phosphate, carbonate, and hydroxyl groups. Moreover, it can be concluded that Zn doping at the tested concentrations is not inducing a specific prokaryote or eukaryote toxicity in HAp compounds.

77. Carbon Nanotubes-Hydroxyapatite Nanocomposites for an Improved Osteoblast Cell Response

Authors: Constanda, S; Stan, MS; Ciobanu, CS; Motelica-Heino, M; Guegan, R; Lafdi, K; Dinischiotu, A; Predoi, D

Published: 2016, JOURNAL OF NANOMATERIALS, 2016, DOI: 10.1155/2016/3941501

An alternative and simple coprecipitation method was developed to obtain carbon nanotube-hydroxyapatite (CNTs:HAp) based nanocomposites. The incorporation of CNTs (in a concentration of 5% and 10% of total weight of the nanocomposite) and their impact on both structural and biological properties were studied by using a set of standard complementary biological, microscopic, and spectroscopic techniques. The characteristic peaks of carbon structure in CNTs were not observed in the CNTs-HAp composites by X-ray diffraction analysis. Moreover, FTIR and Raman spectroscopies confirmed the presence of HAp as the main phase of the synthesized CNTs: HAp nanocomposites. The addition of CNTs considerably affected the nanocomposite morphology by increasing the average crystallite size from 18.7 nm (for raw HAp) to 28.6 nm (for CNTs:HAp-10), confirming their proper incorporation. The biocompatibility evaluation of CNTs:HAp-5 and CNTs:HAp-10 nanocomposites included the assessment of several parameters, such as cell viability, antioxidant response, and lipid peroxidation, on human G-292 osteoblast cell line. Our findings revealed good biocompatibility properties for CNTs: HAp nanocomposites prepared by the coprecipitation method supporting their potential uses in orthopedics and prosthetics.

78. Cerium-doped hydroxyapatite nanoparticles synthesized by the co-precipitation method

Authors: Ciobanu, CS; Popa, CL; Predoi, D

Published: 2016, JOURNAL OF THE SERBIAN CHEMICAL SOCIETY, 81, 446, DOI: 10.2298/JSC150824007C

The present work reports a simple adapted co-precipitation method for the synthesis of stable Ce-substituted Ca hydroxyapatite (HAp) nanoparticles. The structural and morphological properties of the Ce-doped hydroxyapatite (Ce:HAp) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). The optical properties of the Ce-doped hydroxyapatite were also investigated using Fourier transform infrared (FTIR) spectroscopy, Fourier transform Raman spectroscopy and photoluminescence analysis. The results of the XRD studies revealed the progressive increase in the a-and c-axes with increasing Ce concentration. In the FTIR studies of Ce: HAp powders, a structure similar to that of hydroxyapatite was observed. The IR and Raman wavenumbers and the peak strengths of the bands associated with the P-O and O-H bonds decreased progressively with increasing Ce concentration. All the emission maxima could be attributed to 5d-4f transitions of the Ce ions. The displacements of the maximum emission bands with increasing Cerium in the samples were in agreement with the results obtained by XRD studies. The Ce: HAp samples with x(Ce) = 0.03 and 0.05 exhibited significant antibacterial activity against Staphylococcus aureus and Escherichia coli bacterial strains compared to Ce: HAp samples with xCe = 0 (pure HAp) and 0.01.

79. Preliminary Ultrasound Studies On Magnetic Fluids Based on Iron Oxide Nanoparticles

Authors: Popa, CL; Predoi, D; Soare, M; Petre, CC; Predoi, MV

Published: 2016, VIII INTERNATIONAL CONFERENCE ON TIMES OF POLYMERS AND COMPOSITES: FROM AEROSPACE TO NANOTECHNOLOGY, 1736, DOI: 10.1063/1.4949715

The study of various types of nanoparticles with different biomedical applications is of high interest in the last decades. For this purpose, among other techniques, ultrasounds have been used to characterize the aqueous solutions. A non-invasive method is preferable for the characterization of these materials, due to the fact that they are designed to be used for targeted delivery of a chemotherapeutic solution to the tumor site. The present research is focused on ultrasound characterization of solutions based on maghemite and 5-fluorouracil.

80. Magnetite (Fe3O4) nanoparticles as adsorbents for As and Cu removal

Authors: Iconaru, SL; Guegan, R; Popa, CL; Motelica-Heino, M; Ciobanu, CS; Predoi, D

Published: DEC 2016, APPLIED CLAY SCIENCE, 134, 135, DOI: 10.1016/j.clay.2016.08.019

The aim of this study consisted to develop novel synthetic magnetite nanoparticles (nFe(3)O(4)) with preferential reactivity to trace elements (TE) for possible environmental applications as adsorbents. The synthetic magnetite materials obtained through the co-precipitation of both Fe3+ and Fe2+ ions (Fe2+ / Fe3+ = 0.5) were characterized by a set of complementary techniques: X-ray diffraction, transmission and scanning electron microscopy, Fourier transform infrared and Raman spectroscopy, and BET adsorption method. The resulting nFe(3)O(4) displayed a wide specific surface area (100 m(2) g(-1)) with particles reaching a size of about 10 nm, smaller than those of the well-crystallized commercial ones (cFe(3)O(4)) estimated at 80 nm while showing a BET surface area of 6.8 m(2) The adsorption properties of the synthetic nFe(3)O(4) magnetite nanoparticles were characterized and compared to the commercial analogous with the adsorption of both As and Cu. The equilibrium adsorption isotherms were properly fitted with Langmuir and Freundlich equation models and suggested that the developed iron oxides nanoparticles display a certain potential for removal and/or immobilization of TE from contaminated waters and/or soils, with an increase of 69.5% of the adsorbed amount compared to that of the commercial ones. (C) 2016 Elsevier B.V. All rights reserved.

81. Structural Properties and Antifungal Activity against Candida albicans Biofilm of Different Composite Layers Based on Ag/Zn Doped Hydroxyapatite-Polydimethylsiloxanes

Authors: Groza, A; Ciobanu, CS; Popa, CL; Iconaru, SL; Chapon, P; Luculescu, C; Ganciu, M; Predoi, D

Published: APR 2016, POLYMERS, 8, DOI: 10.3390/polym8040131

Modern medicine is still struggling to find new and more effective methods for fighting off viruses, bacteria and fungi. Among the most dangerous and at times life-threatening fungi is Candida albicans. Our work is focused on surface and structural characterization of hydroxyapatite, silver doped hydroxyapatite and zinc doped hydroxyapatite deposited on a titanium substrate previously coated with polydimethylsiloxane (HAp-PDMS, Ag:HAp-PDMS, Zn:HAp-PDMS) by different techniques:Scanning Electron Microscopy (SEM), Glow Discharge Optical Emission Spectroscopy (GDOES) and Fourier Transform Infrared Spectroscopy (FTIR). The morphological studies revealed that the use of the PDMS polymer as an interlayer improves the quality of the coatings. The structural characterizations of the thin films revealed the basic constituents of both apatitic and PDMS structure. In addition, the GD depth profiles indicated the formation of a composite material as well as the successful embedding of the HAp, Zn:HAp and Ag:HAp into the polymer. On the other hand, in vitro evaluation of the antifungal properties of Ag:HAp-PDMS and Zn:HAp-PDMS demonstrated the fungicidal effects of Ag:HAp-PDMS and the potential antifungal effect of Zn:HAp-PDMS composite layers against C. albicans biofilm. The results acquired in this research complete previous research on the potential use of new complex materials produced by nanotechnology in biomedicine.

82. Characterisations of collagen-silver-hydroxyapatite nanocomposites

Authors: Ciobanu, CS; Popa, CL; Petre, CC; Jiga, G; Trusca, R; Predoi, D

Published: 2016, VIII INTERNATIONAL CONFERENCE ON TIMES OF POLYMERS AND COMPOSITES: FROM AEROSPACE TO NANOTECHNOLOGY, 1736, DOI: 10.1063/1.4949723

The XRD analysis were performed to confirm the formation of hydroxyapatite structure in collagen-silver-hydroxyapatite nanocomposites. The molecular interaction in collagen-hydroxyapatite nanocomposites was highlighted by Fourier transform infrared spectroscopy (FTIR) analysis. The SEM showed a nanostructure of collagen-silver-hydroxyapatite nanocomposites composed of nano needle-like particles in a veil with collagen texture. The presence of vibrational groups characteristics to the hydroxyapatite structure in collagen-silver-hydroxyapatite (AgHApColl) nanocomposites was investigated by FTIR.

83. Evaluation of the Antimicrobial Activity of Different Antibiotics Enhanced with Silver-Doped Hydroxyapatite Thin Films

Authors: Predoi, D; Popa, CL; Chapon, P; Groza, A; Iconaru, SL

Published: SEP 2016, MATERIALS, 9, DOI: 10.3390/ma9090778

The inhibitory and antimicrobial effects of silver particles have been known since ancient times. In the last few years, a major health problem has arisen due to pathogenic bacteria resistance to antimicrobial agents. The antibacterial activities of new materials including hydroxyapatite (HAp), silver-doped hydroxyapatite (Ag:HAp) and various types of antibiotics such as tetracycline (T-HAp and T-Ag:HAp) or ciprofloxacin (C-HAp and C-Ag:HAp) have not been studied so far. In this study we reported, for the first time, the preparation and characterization of various thin films based on hydroxyapatite and silver-doped hydroxyapatite combined with tetracycline or ciprofloxacin. The structural and chemical characterization of hydroxyapatite and silver-doped hydroxyapatite thin films has been evaluated by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The morphological studies of the HAp, Ag: HAp, T-HAp, T-Ag: HAp, C-HAp and C-Ag: HAp thin solid films were performed using scanning electron microscopy (SEM). In order to study the chemical composition of the coatings, energy dispersive X-ray analysis (EDX) and glow discharge optical emission spectroscopy (GDOES) measurements have been used, obtaining information on the distribution of the elements throughout the film. These studies have confirmed the purity of the prepared hydroxyapatite and silver-doped hydroxyapatite thin films obtained from composite targets containing Ca10-xAgx(PO4)(6)(OH)(2) with x(Ag) = 0 (HAp) and x(Ag) = 0.2 (Ag: HAp). On the other hand, the major aim of this study was the evaluation of the antibacterial activities of ciprofloxacin and tetracycline in the presence of HAp and Ag: HAp thin layers against Staphylococcus aureus and Escherichia coli strains. The antibacterial activities of ciprofloxacin and tetracycline against Staphylococcus aureus and Escherichia coli test strains increased in the presence of HAp and Ag: HAp thin layers.

84. Inhibitory Effect Evaluation of Glycerol-Iron Oxide Thin Films on Methicillin-Resistant Staphylococcus aureus

Authors: Popa, CL; Prodan, AM; Chapon, P; Turculet, C; Predoi, D

Published: 2015, JOURNAL OF NANOMATERIALS, 2015, DOI: 10.1155/2015/465034

The main purpose of this study was to evaluate the inhibitory effect of glycerol- iron oxide thin films on Methicillin-Resistant Staphylococcus aureus (MRSA). Our results suggest that glycerol-iron oxide thin films could be used in the future for various biomedical and pharmaceutical applications. The glycerol-iron oxide thin films have been deposited by spin coating method on a silicon (111) substrate. The structural properties have been studied by X-ray diffraction (XRD) and scanning electron spectroscopy (SEM). The XRD investigations of the prepared thin films demonstrate that the crystal structure of glycerol-iron oxide nanoparticles was not changed after spin coating deposition. On the other hand, the SEM micrographs suggest that the size of the glycerol-iron oxide microspheres increased with the increase of glycerol exhibiting narrow size distributions. The qualitative depth profile of glycerol-iron oxide thin films was identified by glow discharge optical emission spectroscopy (GDOES). The GDOES spectra revealed the presence of the main elements: Fe, O, C, H, and Si. The antimicrobial activity of glycerol-iron oxide thin films was evaluated by measuring the zone of inhibition. After 18 hours of incubation at 37 degrees C, the diameters of the zones of complete inhibition have been measured obtaining values around 25 mm.

85. Influence of Thermal Treatment on the Antimicrobial Activity of Silver-Doped Biological Apatite

Authors: Popa, CL; Ciobanu, CS; Voicu, G; Vasile, E; Chifiriuc, MC; Iconaru, SL; Predoi, D

Published: DEC 29 2015, NANOSCALE RESEARCH LETTERS, 10, DOI: 10.1186/s11671-015-1211-x

In this paper, we report the structural and morphological properties of silver-doped hydroxyapatite (AgHAp) with a silver concentration x(Ag) = 0.5 before and after being thermal treated at 600 and 1000 degrees C. The results obtained by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy suggest that the structure of the samples changes gradually, from hydroxyapatite (AgHAp_40) to a predominant beta-TCP structure (AgHAp_1000), achieved when the thermal treatment temperature is 1000 degrees C. In the AgHAp_600 sample, the presence of two phases, HAp and beta-TCP, was highlighted. Also, scanning electron microscopy studies suggest that the shape and dimension of the nanoparticles begin to change when the temperature increases. The antimicrobial activity of the obtained compounds was evaluated against Klebsiella pneumoniae, Staphylococcus aureus, and Candida albicans strains.

86. Antimicrobial activity of zinc doped hydroxyapaptite prepared by co-precipitation method

Authors: Popa, CL; Ciobanu, CS; Prodan, AM; Turculet, C; Badea, ML; Predoi, D

Published: OCT 16 2015, TOXICOLOGY LETTERS, 238, S198, DOI: 10.1016/j.toxlet.2015.08.596

87. Antimicrobial Activity Evaluation on Silver Doped Hydroxyapatite/Polydimethylsiloxane Composite Layer

Authors: Ciobanu, CS; Groza, A; Iconaru, SL; Popa, CL; Chapon, P; Chifiriuc, MC; Hristu, R; Stanciu, GA; Negrila, CC; Ghita, RV; Ganciu, M; Predoi, D

Published: 2015, BIOMED RESEARCH INTERNATIONAL, 2015, DOI: 10.1155/2015/926513

The goal of this study was the preparation, physicochemical characterization, and microbiological evaluation of novel hydroxyapatite doped with silver/polydimethylsiloxane (Ag:HAp-PDMS) composite layers. In the first stage, the deposition of polydimethylsiloxane (PDMS) polymer layer on commercially pure Si disks has been produced in atmospheric pressure corona discharges. Finally, the new silver doped hydroxyapatite/polydimethylsiloxane composite layer has been obtained by the thermal evaporation technique. The Ag: HAp-PDMS composite layers were characterized by various techniques, such as Scanning Electron Microscopy (SEM), Glow Discharge Optical Emission Spectroscopy (GDOES), and X-ray photoelectron spectroscopy (XPS). The antimicrobial activity of the Ag:HAp-PDMS composite layer was assessed against Candida albicans ATCC 10231 (ATCC-American Type Culture Collection) by culture based and confirmed by SEM and Confocal Laser Scanning Microscopy (CLSM) methods. This is the first study reporting the antimicrobial effect of the Ag: HAp-PDMS composite layer, which proved to be active against Candida albicans biofilm embedded cells.

88. Physicochemical Analysis of the Polydimethylsiloxane Interlayer Influence on a Hydroxyapatite Doped with Silver Coating

Authors: Popa, CL; Groza, A; Chapon, P; Ciobanu, CS; Ghita, RV; Trusca, R; Ganciu, M; Predoi, D

Published: 2015, JOURNAL OF NANOMATERIALS, 2015, DOI: 10.1155/2015/250617

We investigate by different complementary methods the processes occurring when a polydimethylsiloxane film is used as interlayer for a silver doped hydroxyapatite coating. The X-ray diffraction and Fourier Transform Infrared Spectroscopy measurements show that the hydroxyapatite doped with silver is in a crystalline form and some SiO44- ions formation takes place at the surface and in the bulk of the new hydroxyapatite doped with silver/polydimethylsiloxane composite layer. The possibility of SiO44- ions incorporation in the structure of silver doped hydroxyapatite by the mechanism of SiO44-/PO43- ions substitution is analysed. The new formed silver doped hydroxyapatite/polydimethylsiloxane composite layer is compact, homogeneous, with no cracks as it was shown by Scanning Electron Microscopy and Glow Discharge Optical Emission Spectrometry.

89. Evaluation of Samarium Doped Hydroxyapatite, Ceramics for Medical Application: Antimicrobial Activity

Authors: Ciobanu, CS; Iconaru, SL; Popa, CL; Motelica-Heino, M; Predoi, D

Published: 2015, JOURNAL OF NANOMATERIALS, 2015, DOI: 10.1155/2015/849216

Samarium doped hydroxyapatite (Sm:HAp), Ca10-xSmx(PO4)(6)(OH)(2) (HAp), bionanoparticles with different x(Sm) have been successfully synthesized by coprecipitation method. Detailed characterization of samarium doped hydroxyapatite nanoparticles (Sm: HAp-NPs) was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The biocompatibility of samarium doped hydroxyapatite was assessed by cell viability. The antibacterial activity of the Sm: HAp-NPs was tested against Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) andGram-positive bacteria (Enterococcus faecalis and Staphylococcus aureus). A linear increase of antimicrobial activity of P. aeruginosa has been observed when concentrations of Sm: HAp-NPs in the samples with x(Sm) = 0.02 were higher than 0.125 mg/mL. For Sm: HAp-NPs with x(Sm) = 0.05 a significant increase of antibacterial activity on E. coli was observed in the range 0.5-1 mg/mL. For low concentrations of Sm: HAp-NPs (x(Sm) = 0.05) from 0.031 to 0.125 mg/mL a high antibacterial activity on Enterococcus faecalis has been noticed. A growth of the inhibitory effect on S. aureus was observed for all concentrations of Sm: HAp-NPs with x(Sm) = 0.02.

90. Advances in Functionalized Materials Research

Authors: Predoi, D; Motelica-Heino, M; Le Coustumer, P

Published: 2015, JOURNAL OF NANOMATERIALS, 2015, DOI: 10.1155/2015/412690

91. Optical properties and antimicrobial activity evaluation of europium/silver doped hydroxyapatite nanoparticles

Authors: Ciobanu, CS; Prodan, AM; Turculet, C; Iordache, F; Iconaru, SL; Popa, CL; Badea, ML; Predoi, D

Published: OCT 16 2015, TOXICOLOGY LETTERS, 238, S198, DOI: 10.1016/j.toxlet.2015.08.595

92. OPTICAL CHARACTERISTICS OF SULPHUR-PASSIVATED n-GaAs (100) SURFACE

Authors: Ghita, RV; Grigorescu, CEA; Secu, M; Predoi, D; Frumosu, F; Cotirlan, C; Feraru, ID

Published: OCT-DEC 2014, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 9, 1478, DOI:

A genuine GaAs surface is covered with a relatively thick layer (similar to 10 nm) of native oxide pinning the surface Fermi level within the band gap of semiconductor. The method presented in this work is related to the sulphur passivation by treating n-GaAs(100) and (110) in sulphide solutions (e.g pure ammonium sulphide and sulphur monochloride) that combines both chemical electronic passivation by reducing the surface state density. The effects of passivation were put into evidence by Photoluminescence measurements where it was observed the variation of state density. The presence of sulphur dipoles at surface was presented in a diagram of Second Harmonic Generation analysis and the general aspect of sulphur compound was identified by SEM images. The presence of the covalent bond Ga-S and the variation of surface barrier as well as the effect of crystal orientation were put into evidence by micro-Raman Spectroscopy. At the surface of n-GaAs it is developed an adherent layer of sulphur compound as a resul of chemical interaction of sulphur ions with n-GaAs surface.

93. Antimicrobial Activity of Thin Solid Films of Silver Doped Hydroxyapatite Prepared by Sol-Gel Method

Authors: Iconaru, SL; Chapon, P; Le Coustumer, P; Predoi, D

Published: 2014, SCIENTIFIC WORLD JOURNAL, DOI: 10.1155/2014/165351

In this work, the preparation and characterization of silver doped hydroxyapatite thin films were reported and their antimicrobial activity was characterized. Silver doped hydroxyapatite (Ag:HAp) thin films coatings substrate was prepared on commercially pure Si disks by sol-gel method. The silver doped hydroxyapatite thin films were characterized by various techniques such as Scanning electron microscopy (SEM) with energy Dispersive X-ray attachment (X-EDS), Fourier transform infrared spectroscopy (FTIR), and glow discharge optical emission spectroscopy (GDOES). These techniques have permitted the structural and chemical characterisation of the silver doped hydroxyapatite thin films. The antimicrobial effect of the Ag:HAp thin films on Escherichia coli and Staphylococcus aureus bacteria was then investigated. This is the first study on the antimicrobial effect of Ag:HAp thin films obtained by sol-gel method. The results of this study have shown that the Ag:HAp thin films with x(Ag) = 0.5 are effective against E. coli and S. aureus after 24 h.

94. Systematic investigation and in vitro biocompatibility studies on mesoporous europium doped hydroxyapatite

Authors: Popa, CL; Ciobanu, CS; Iconaru, SL; Stan, M; Dinischiotu, A; Negrila, CC; Motelica-Heino, M; Guegan, R; Predoi, D

Published: OCT 2014, CENTRAL EUROPEAN JOURNAL OF CHEMISTRY, 12, 1046, DOI: 10.2478/s11532-014-0554-y

This paper reports the systematic investigation of europium doped hydroxyapatite (Eu:HAp). A set of complementary techniques, namely Fourier Transform Infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller (BET) technique were used towards attaining a detailed understanding of Eu:HAp. The XPS analysis confirmed the substitution of Ca ions by Eu ions in the Eu:HAp samples. Secondly, Eu:HAp and pure HAp present type IV isotherms with a hysteresis loop at a relative pressure (P/P-0) between 0.4 and 1.0, indicating the presence of mesopores. Finally, the in vitro biological effects of Eu:HAp nanoparticles were evaluated by focusing on the F-actin filament pattern and heat shock proteins (Hsp) expression in HEK293 human kidney cell line. Fluorescence microscopy studies of the actin protein revealed no changes of the immunolabelling profile in the renal cells cultured in the presence of Eu:HAp nanoparticles. Hsp60, Hsp70 and Hsp90 expressions measured by Western blot analysis were not affected after 24 and 48 hours exposure. Taken together, these results confirmed the lack of toxicity and the biocompatibility of the Eu:HAp nanoparticles. Consequently, the possibility of using these nanoparticles for medical purposes without affecting the renal function can be envisaged.

95. Hydroxyapatite With Environmental Applications

Authors: Popa, CL; Ciobanu, CS; Petre, CC; Motelica-Heino, M; Iconaru, SL; Jiga, G; Predoi, D

Published: 2014, TIMES OF POLYMERS (TOP) AND COMPOSITES 2014, 1599, 321, DOI: 10.1063/1.4876842

The aim of this study was to synthetize new nanoparticles based on methyltrimethoxysilane coated hydroxyapatite (MTHAp) for lead removal in aqueous solutions. The morphological and compositional analysis of MTHAp was investigated by scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). Removal experiments of Pb2+ ions were carried out in aqueous solutions with controlled concentration of Pb2+ and at fixed pH of 5. After the removal experiment of Pb2+ ions from solutions, porous hydroxyapatite nanoparticles were transformed into PbMTHAp_5 via the adsorption of Pb2+ ions followed by a cation exchange reaction. Our results demonstrate that the porous hydroxyapatite nanoparticles can be used as an adsorbent for removing Pb2+ ions from aqueous solution.

96. In vivo toxicity studies of superparamagnetic iron oxide nanoparticles in a silica matrix

Authors: Iconaru, SL; Prodan, AM; Ciobanu, CS; Motelica-Heino, M; Predoi, D

Published: SEP 2014, FEBS JOURNAL, 281, 748, DOI:

97. Mechanisms of pulmonary toxicity developed at low and high doses of dextran-coated magnetite nanoparticles

Authors: Radu, M; Gheorghiu, A; Predoi, D; Hermenean, A; Ardelean, A; Dinischiotu, A

Published: SEP 10 2014, TOXICOLOGY LETTERS, 229, S78, DOI: 10.1016/j.toxlet.2014.06.301

98. Antimicrobial studies on porous hydroxyapatite used in the environment and biological applications

Authors: Ciobanu, CS; Iconaru, SL; Predoi, D

Published: SEP 2014, FEBS JOURNAL, 281, 730, DOI:

99. Porous Methyltrimethoxysilane Coated Nanoscale-Hydroxyapatite for Removing Lead Ions from Aqueous Solutions

Authors: Ciobanu, CS; Iconaru, SL; Popa, CL; Costescu, A; Motelica-Heino, M; Predoi, D

Published: 2014, JOURNAL OF NANOMATERIALS, 2014, DOI: 10.1155/2014/361061

The aim of this study was to synthetize new porous nanoparticles based on methyltrimethoxysilane coated hydroxyapatite (MTHAp) for lead removal form aqueous solutions. The morphological and compositional analysis of MTHAp were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). Removal experiments of Pb2+ ions were carried out in aqueous solutions with controlled concentration of Pb2+ at a fixed pH value of 3 and 5 respectively. After the removal experiment of Pb2+ ions from solutions, porous hydroxyapatite nanoparticles were transformed into PbMTHAp_3 and PbMTHAp_5 via the adsorption of Pb2+ ions followed by a cation exchange reaction. The X-ray diffraction spectra of PbMTHAp_3 and PbMTHAp_5 revealed that the powders, after removal of the Pb2+ ions, were a mixture of Ca2.5Pb7.5(PO4)(6) (OH) 2, Pb2Ca4(PO4)(2)(SiO4), and Ca-10(PO4)(6)(OH)(2). Our results demonstrate that the porous hydroxyapatite nanoparticles can be used as an adsorbent for removing Pb2+ ions from aqueous solutions.

100. In vivo toxicity studies of dextran coated iron oxide nanoparticles

Authors: Prodan, AM; Iconaru, SL; Popa, CL; Predoi, D

Published: SEP 2014, FEBS JOURNAL, 281, 573, DOI:

101. Toxicity Evaluation following Intratracheal Instillation of Iron Oxide in a Silica Matrix in Rats

Authors: Prodan, AM; Ciobanu, CS; Popa, CL; Iconaru, SL; Predoi, D

Published: 2014, BIOMED RESEARCH INTERNATIONAL, 2014, DOI: 10.1155/2014/134260

Iron oxide-silica nanoparticles (IOSi-NPs) were prepared from a mixture of ferrous chloride tetrahydrate and ferric chloride hexahydrate dropped into a silica xerogel composite. The structure and morphology of the synthesized maghemite nanoparticles into the silica xerogel were analysed by X-ray diffraction measurements, scanning electron microscopy equipped with an energy dispersive X-ray spectrometer, and transmission electron microscopy. The results of the EDAX analysis indicated that the embedded particles were iron oxide nanoparticles. The particle size of IOSi-NPs calculated from the XRD analysis was estimated at around 12.5 nm. The average size deduced from the particle size distribution is 13.7 +/- 0.6 nm, which is in good agreement with XRDanalysis. The biocompatibility of IOSi-NPs was assessed by cell viability and cytoskeleton analysis. Histopathology analysis was performed after 24 hours and 7 days, respectively, from the intratracheal instillation of a solution containing 0.5, 2.5, or 5mg/ kg IOSi-NPs. The pathological micrographs of lungs derived from rats collected after the intratracheal instillation with a solution containing 0.5mg/kg and 2.5mg/ kg IOSi-NPs show that the lung has preserved the architecture of the control specimen with no significant differences. However, even at concentrations of 5mg/ kg, the effect of IOSi-NPS on the lungs was markedly reduced at 7 days post treatment.

102. Sm:HAp Nanopowders Present Antibacterial Activity against Enterococcus faecalis

Authors: Ciobanu, CS; Popa, CL; Predoi, D

Published: 2014, JOURNAL OF NANOMATERIALS, 2014, DOI: 10.1155/2014/780686

The synthesis of nanoparticles with inhibitory and bactericidal effects represents a great interest in development of new materials for biological applications. In this paper we present for the first time the synthesis of Ca10-xSmx(PO4)(6)(OH)(2) nanoparticles at low temperature and primary tests concerning the adherence of Enterococcus faecalis ATCC 29212 (gram-positive bacteria). All the XRD peaks were indexed in accordance with the hexagonal HAp in P63m space group. The EDAX spectrum and elemental mapping of O, P, Ca, and Sm demonstrate that all the elements were homogeneously distributed in Ca Sm-10-x(x).(PO4)(6)(OH)(2) with x(Sm) = 0.03. The peaks at 347.3 eV, 532.1 eV, and 133.8 eV in the XPS spectra can be attributed to the binding energy of Ca 2p, O is, and P 2p. The peak at 1084.4 eV observed in Ca Sm-10-x(x)(PO4)(6)(OH)(2) was attributed to the Sm 3d(5/2). Bacterial adhesion was reduced on Ca Sm-10-x(x)(PO4)(6)(OH)(2) sample when compared to pure HAp (x(Sm) = 0) and significant differences in bacterial adhesion on pure HAp (x = 0) and Sm:HAp (x(Sm) = 0.01,x(Sm) = 0.03, and x(Sm) = 0.1) were observed. The bacterial adhesion decreased when the samarium concentrations increased. Finally, we demonstrate that the Sm: HAp nanopowder with x(Sm) > 0 showed high antibacterial activity against Enterococcus faecalis ATCC 29212.

103. Antimicrobial activity of samarium doped hydroxyapaptite prepared by co-precipitation method

Authors: Ciobanu, CS; Popa, CL; Iconaru, SL; Predoi, D

Published: SEP 2014, FEBS JOURNAL, 281, 651, DOI:

104. Magnetic Properties and Biological Activity Evaluation of Iron Oxide Nanoparticles

Authors: Prodan, AM; Iconaru, SL; Chifiriuc, CM; Bleotu, C; Ciobanu, CS; Motelica-Heino, M; Sizaret, S; Predoi, D

Published: 2013, JOURNAL OF NANOMATERIALS, 2013, DOI: 10.1155/2013/893970

The aim of this study was to provide information about the biological properties of iron oxide nanoparticles (IO-NPs) obtained in an aqueous suspension. The IO-NPs were characterized by transmission electron microscopy (TEM). Analysis of hysteresis loops data at room temperature for magnetic IO-NPs sample indicated that the IO-NPs were superparamagnetic at room temperature. The calculated saturation magnetization for magnetic iron oxide was M-s = 18.1 emu/g. The antimicrobial activity of the obtained PMC-NPs was tested against Gram-negative (Pseudomonas aeruginosa 1397, Escherichia coli ATCC 25922), Gram-positive (Enterococcus faecalis ATCC 29212, Bacillus subtilis IC 12488) bacterial as well as fungal (Candida krusei 963) strains. The obtained results suggested that the antimicrobial activity of IO-NPs is dependent on the metallic ions concentrations and on the microbial growth state, either planktonic or adherent. The obtained IO-NPs exhibited no cytotoxic effect on HeLa cells at the active antimicrobial concentrations.

105. Synthesis and Antimicrobial Activity of Silver-Doped Hydroxyapatite Nanoparticles

Authors: Ciobanu, CS; Iconaru, SL; Chifiriuc, MC; Costescu, A; Le Coustumer, P; Predoi, D

Published: 2013, BIOMED RESEARCH INTERNATIONAL, 2013, DOI: 10.1155/2013/916218

The synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is of great interest for the development of new biomedical applications.. e aim of this study was the evaluation of Ca10-xAgx(PO4)(6)(OH)(2) nanoparticles (Ag:HAp-NPs) for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years and became a major health problem. Here, we report a method for synthesizing Ag doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100 degrees C in deionised water. Also, in this paper Ag:HAp-NPs are evaluated for their antimicrobial activity against ram-positive and ram-negative bacteria and fungal strains. The specific antimicrobial activity revealed by the qualitative assay is demonstrating that our compounds are interacting differently with the microbial targets, probably due to the differences in the microbial wall structures.

106. Phytosynthesis of gold nanoparticles using caesalpinia pulcherrima (peacock flower) flower extract and evaluation of their antimicrobial activities

Authors: Nagaraj, B; Divya, TK; Barasa, M; Krishnamurthy, NB; Dinesh, R; Negrila, CC; Predoi, D

Published: MAR-APR 2013, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 15, 304, DOI:

Caesalpinia pulcherrima (Linn) popularly known as Peacock flower in India belongs to family Caesalpiniace. In this work, we describe environment friendly technique for green synthesis of gold nanoparticles from AuCl4 solution using the Caesalpinia pulcherrima (Peacock flower) flower extract as reducing agent. The gold nanoparticles were characterized using UV-visible spectroscopy and transmission electron microscopy (TEM). The UV- visible spectra indicate a strong Plasmon resonance that is located at similar to 450 nm. The TEM analysis shows that products have spherical morphology with size ranging between 1.0-50 nm. The study also indicates that gold nanoparticles show good antimicrobial activities when compared to the standard antibiotics.

107. Study on Europium-Doped Hydroxyapatite Nanoparticles by Fourier Transform Infrared Spectroscopy and Their Antimicrobial Properties

Authors: Iconaru, SL; Motelica-Heino, M; Predoi, D

Published: 2013, JOURNAL OF SPECTROSCOPY, 2013, DOI: 10.1155/2013/284285

Fourier transform infrared spectroscopy (FT-IR) analysis was conducted on europium-doped hydroxyapatite, Ca10-xEux (PO4)(6)(OH)(2) nanocrystalline powders (Eu:HAp) with 0 < x(Eu) < 0.2. Antimicrobial studies were also performed for the first time on Eu: HAp. The antimicrobial properties of Eu: HAp nanoparticles with 0 < x(Eu) <= 0.2 on Gram-negative (E. coli ATCC 25922, Pseudomonas aeruginosa 1397) andGram-positive (Staphylococcus aureus 0364, Enterococcus faecalis ATCC 29212) bacteria systems and a species of fungus (Candida albicans ATCC 10231) were reported. Our study demonstrates that the antimicrobial activity of Eu: HAp nanoparticles is dependent on the europium concentration.

108. Structural properties of silver doped hydroxyapatite and their biocompatibility

Authors: Ciobanu, CS; Iconaru, SL; Pasuk, I; Vasile, BS; Lupu, AR; Hermenean, A; Dinischiotu, A; Predoi, D

Published: APR 1 2013, MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS, 33, 1402, DOI: 10.1016/j.msec.2012.12.042

The aim of this study was to obtain a novel hydroxyapatite-based material with high biocompatibility. The structural properties of the samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). The X-ray diffraction studies revealed the characteristic peaks of hydroxyapatite in each sample. Other phases or impurities were not observed. The scanning electron microscopy observations suggest that the doping components have no influence on the surface morphology of the samples, which reveals a homogeneous aspect of the synthesized particles for all samples. The presence of calcium (Ca), phosphor (P), oxygen (O) and silver (Ag) in the Ag:HAp is confirmed by energy dispersive X-ray (EDAX) and X-ray Photoelectron Spectroscopy analyses. Nanocrystalline silver doped HAp stimulated viability and potentiated the activation of murine macrophages. (C) 2012 Elsevier B.V. All rights reserved.

109. Fabrication, Characterization, and Antimicrobial Activity, Evaluation of Low Silver Concentrations in Silver-Doped Hydroxyapatite Nanoparticles

Authors: Costescu, A; Ciobanu, CS; Iconaru, SL; Ghita, RV; Chifiriuc, CM; Marutescu, LG; Predoi, D

Published: 2013, JOURNAL OF NANOMATERIALS, 2013, DOI: 10.1155/2013/194854

The aim of this study was the evaluation of (Ca10-x Ag-x)(PO4)(6) (OH)(2) nanoparticles (Ag:HAp-NPs) for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years as a major public health problem worldwide. In this paper, we report a comparison of the antimicrobial activity of low concentrations silver-doped hydroxyapatite nanoparticles. Thesilver-doped nanocrystalline hydroxyapatite powder was synthesized at 100 degrees C indeionised water. The as-prepared Ag: Hap nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR, and FT-Raman spectroscopy. X-ray diffraction (XRD) studies demonstrate that powders obtained by coprecipitation at 100 degrees C exhibit the apatite characteristics with good crystal structure, without any new phase or impurities found. FT-IR and FT-Raman spectroscopy revealed the presence of the various vibrational modes corresponding to phosphates and hydroxyl groups and the absence of any band characteristic to silver. The specific microbiological assays demonstrated that Ag: HAp-NPs exhibited antimicrobial features, but interacted differently with the Gram-positive, Gram-negative bacterial and fungal tested strains.

110. Anti-biofilm activity of maghemite nanoparticles coated with dextran

Authors: Ciobanu, CS; Iconaru, SL; Predoi, D

Published: JUL 2013, FEBS JOURNAL, 280, 359, DOI:

111. Antimicrobial activity of silver doped hydroxyapaptite thin films

Authors: Ciobanu, CS; Iconaru, SL; Chapon, P; Predoi, D

Published: JUL 2013, FEBS JOURNAL, 280, 360, DOI:

112. Synthesis and Antibacterial and Antibiofilm Activity of Iron Oxide Glycerol Nanoparticles Obtained by Coprecipitation Method

Authors: Iconaru, SL; Prodan, AM; Le Coustumer, P; Predoi, D

Published: 2013, JOURNAL OF CHEMISTRY, 2013, DOI: 10.1155/2013/412079

The glycerol iron oxide nanoparticles (GIO-NPs) were obtained by an adapted coprecipitation method. The X-ray diffraction (XRD) studies demonstrate that GIO-NPs were indexed into the spinel cubic lattice with a lattice parameter of 0.835 nm. The refinement of XRD spectra indicated that no other phases except maghemite were detected. The adsorption of glycerol on iron oxide nanoparticles was investigated by Fourier transform infrared (FTIR) spectroscopy. On the other hand, this work implicated the use of GIO-NPs in antibacterial studies. The results indicate that, in the case of P.aeruginosa 1397 biofilms, at concentrations from 0.01 mg/mL to 0.625 mg/mL, the glycerol iron oxide inhibits the ability of this strain to develop biofilms on the inert substratum.

113. Vibrational Investigations of Silver-Dovep Hydroxyapatite with Antibacterial Properties

Authors: Ciobanu, CS; Iconaru, SL; Le Coustumer, P; Predoi, D

Published: 2013, JOURNAL OF SPECTROSCOPY, 2013, DOI: 10.1155/2013/471061

Silver-doped hydroxyapatite (Ag:HAp) was obtained by coprecipitation method. Transmission electron microscopy (TEM), infrared, and Raman analysis confirmed the development of Ag:HAp with good crystal structure. Transmission electron microscopy analysis showed an uniform ellipsoidal morphology with particles from 5 nm to 15 nm. The main vibrational bands characteristic to HAp were identified. The bands assigned to phosphate vibrational group were highlighted in infrared and Raman spectra. The most intense peak Raman spectrum is the narrow band observed at 960 cm(-1). In this article Ag:Hap-NPs were also evaluated for their antimicrobial activities against gram-positive, gram-negative, and fungal strains. The specific antimicrobial activity revealed by the qualitative assay demonstrates that our compounds are interacting differently with the microbial targets.

114. Toxicological aspects of PANC-1 cells exposure to iron oxide dextran-covered nanoparticles

Authors: Radu, M; Burtea, C; Predoi, D; Muller, R; Dinischiotu, A

Published: JUL 2013, FEBS JOURNAL, 280, 216, DOI:

115. Structural Characterization and Magnetic Properties of Iron Oxides Biological Polymers

Authors: Iconaru, SL; Ciobanu, CS; Le Coustumer, P; Predoi, D

Published: APR 2013, JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, 26, 855, DOI: 10.1007/s10948-012-1855-z

Iron oxide nanoparticles (IONs) coated with different biological (dextran, sucrose) polymers have been synthesized by the coprecipitation method. Biological polymers coated iron oxide nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM). Zero field cooled and field cooled magnetizations measurements are also reported. We present a preliminary study of the influence of biological polymer on the interaction effects in powders. The temperature, T (max), of the maximum, increased from 25 K (dextran) to 52 K (sucrose). These values are due to the decrease of interparticle interactions, mainly as a result of the interparticle distance increase.

116. Iron Oxide Magnetic Nanoparticles: Characterization and Toxicity Evaluation by In Vitro and In Vivo Assays

Authors: Prodan, AM; Iconaru, SL; Ciobanu, CS; Chifiriuc, MC; Stoicea, M; Predoi, D

Published: 2013, JOURNAL OF NANOMATERIALS, 2013, DOI: 10.1155/2013/587021

The aim of this study was to evaluate the biological properties of iron oxide nanoparticles (IO-NPs) obtained in the aqueous suspension. The iron oxide nanoparticles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The biocompatibility of the iron oxide was demonstrated by the in vitro quantification of HeLa cells viability using propidium iodide (PI) and fluorescein diacetate (FdA) and the MTT colorimetric assay. The toxicity of small size iron oxide nanoparticles was also evaluated by means of histological examination on male Brown Norway rats after intraperitoneal injection. At the tested concentrations, the nanoparticles proved to be not cytotoxic on HeLa cells. The rat's behavior, as well as the histopathological aspect of liver, kidney, lung, and spleen tissues at 48 h after intraperitoneal injection did not present any modifications. The in vivo and in vitro assays suggested that the IO-NPs could be further used for developing new in vivo medical applications.

117. The antimicrobial activity of fabricated iron oxide nanoparticles

Authors: Iconaru, SL; Ciobanu, CS; Prodan, AM; Predoi, D

Published: SEP 2012, FEBS JOURNAL, 279, 98, DOI:

118. Hybrid dextran-iron oxide thin films deposited by laser techniques for biomedical applications

Authors: Predoi, D; Ciobanu, CS; Radu, M; Costache, M; Dinischiotu, A; Popescu, C; Axente, E; Mihailescu, IN; Gyorgy, E

Published: MAR 1 2012, MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS, 32, 302, DOI: 10.1016/j.msec.2011.10.032

Iron oxide oxide nanoparticles were prepared by chemical co-precipitation method. The nanoparticles were mixed with dextran in distilled water. The obtained solutions were frozen in liquid nitrogen and used as targets during matrix assisted pulsed laser evaporation for the growth of hybrid, iron oxide nanoparticles-dextran thin films. Fourier Transform Infrared Spectroscopy and X-ray diffraction investigations revealed that the obtained films preserve the structure and composition of the initial, non-irradiated iron oxide-dextran composite material. The biocompatibility of the iron oxide-dextran thin films was demonstrated by 3-(4.5 dimethylthiazol-2yl)-2.5-diphenyltetrazolium bromide-based colorimetric assay, using human liver hepatocellular carcinoma cells. (C) 2011 Elsevier B.V. All rights reserved.

119. Biomedical properties and preparation of iron oxide-dextran nanostructures by MAPLE technique

Authors: Ciobanu, CS; Iconaru, SL; Gyorgy, E; Radu, M; Costache, M; Dinischiotu, A; Le Coustumer, P; Lafdi, K; Predoi, D

Published: MAR 13 2012, CHEMISTRY CENTRAL JOURNAL, 6, DOI: 10.1186/1752-153X-6-17

Background: In this work the chemical structure of dextran-iron oxide thin films was reported. The films were obtained by MAPLE technique from composite targets containing 10 wt. % dextran with 1 and 5 wt.% iron oxide nanoparticles (IONPs). The IONPs were synthesized by co-precipitation method. A KrF* excimer laser source (lambda = 248 nm, tau(FWHM)congruent to 25 ns, nu = 10 Hz) was used for the growth of the hybrid, iron oxide NPs-dextran thin films. Results: Dextran coated iron oxide nanoparticles thin films were indexed into the spinel cubic lattice with a lattice parameter of 8.36 angstrom. The particle sized calculated was estimated at around 7.7 nm. The XPS shows that the binding energy of the Fe 2p(3/2) of two thin films of dextran coated iron oxide is consistent with Fe3+ oxides. The atomic percentage of the C, O and Fe are 66.71, 32.76 and 0.53 for the films deposited from composite targets containing 1 wt.% maghemite and 64.36, 33.92 and 1.72 respectively for the films deposited from composite targets containing 5 wt.% maghemite. In the case of cells cultivated on dextran coated 5% maghemite gamma-Fe2O3, the number of cells and the level of F-actin were lower compared to the other two types of thin films and control. Conclusions: The dextran-iron oxide continuous thin films obtained by MAPLE technique from composite targets containing 10 wt.% dextran as well as 1 and 5 wt.% iron oxide nanoparticles synthesized by co-precipitation method presented granular surface morphology. Our data proved a good viability of Hep G2 cells grown on dextran coated maghemite thin films. Also, no changes in cells morphology were noticed under phase contrast microscopy. The data strongly suggest the potential use of iron oxide-dextran nanocomposites as a potential marker for biomedical applications.

120. Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria

Authors: Ciobanu, CS; Iconaru, SL; Le Coustumer, P; Constantin, LV; Predoi, D

Published: JUN 21 2012, NANOSCALE RESEARCH LETTERS, 7, DOI: 10.1186/1556-276X-7-324

Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10-x Ag (x) (PO4)(6)(OH)(2), x (Ag) = 0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a = b = 9.435 , c = 6.876 for x (Ag) = 0.05, a = b = 9.443 , c = 6.875 for x (Ag) = 0.2, and a = b = 9.445 , c = 6.877 for x (Ag) = 0.3 are in good agreement with the standard of a = b = 9.418 , c = 6.884 (space group P6(3)/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples (x (Ag) = 0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of x (Ag) in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth (P. stuartii).

121. Evaluation of antibacterial effect of silver doped hydroxyapatite nanoparticles

Authors: Prodan, AM; Le Coustumer, P; Predoi, D

Published: SEP 2012, FEBS JOURNAL, 279, 98, DOI:

122. PHYTOSYNTHESIS OF GOLD NANOPARTICLES USING CAESALPINIA PULCHERRIMA (PEACOCK FLOWER) FLOWER EXTRACT AND EVALUATION OF THEIR ANTIMICROBIAL ACTIVITIES

Authors: Nagaraj, B; Divya, TK; Barasa, M; Krishnamurthy, NB; Dinesh, R; Negrila, CC; Predoi, D

Published: JUL-SEP 2012, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 7, 905, DOI:

Caesalpinia pulcherrima (Linn) popularly known as Peacock flower in India belongs to family Caesalpiniace. In this work, we describe environment friendly technique for green synthesis of gold nanoparticles from AuCl4 solution using the Caesalpinia pulcherrima (Peacock flower) flower extract as reducing agent. The gold nanoparticles were characterized using UV-visible spectroscopy and transmission electron microscopy (TEM). The UV-visible spectra indicate a strong Plasmon resonance that is located at similar to 450 nm. The TEM analysis shows that products have spherical morphology with size ranging between 10-50 nm. The study also indicates that gold nanoparticles show good antimicrobial activities when compared to the standard antibiotics.

123. Synthesis and characterization of polysaccharide-maghemite composite nanoparticles and their antibacterial properties

Authors: Iconaru, SL; Prodan, AM; Motelica-Heino, M; Sizaret, S; Predoi, D

Published: OCT 22 2012, NANOSCALE RESEARCH LETTERS, 7, DOI: 10.1186/1556-276X-7-576

The aim of this study was to obtain saccharide (dextran and sucrose)-coated maghemite nanoparticles with antibacterial activity. The polysaccharide-coated maghemite nanoparticles were synthesized by an adapted coprecipitation method. X-ray diffraction (XRD) studies demonstrate that the obtained polysaccharide-coated maghemite nanoparticles can be indexed into the spinel cubic lattice with a lattice parameter of 8.35 angstrom. The refinement of XRD spectra indicated that no other phases except the maghemite are detectable. The characterization of the polysaccharide-coated maghemite nanoparticles by various techniques is described. The antibacterial activity of these polysaccharide-coated maghemite nanoparticles (NPs) was tested against Pseudomonas aeruginosa 1397, Enterococcus faecalis ATCC 29212, Candida krusei 963, and Escherichia coli ATCC 25922 and was found to be dependent on the polysaccharide type. The antibacterial activity of dextran-coated maghemite was significantly higher than that of sucrose-coated maghemite. The antibacterial studies showed the potential of dextran-coated iron oxide NPs to be used in a wide range of medical infections.

124. BIOCOMPATIBLE MAGNETIC IRON OXIDE NANOPARTICLES DOPED DEXTRAN THIN FILMS PRODUCED BY SPIN COATING DEPOSITION SOLUTION

Authors: Iconaru, SL; Andronescu, E; Ciobanu, CS; Prodan, AM; Le Coustumer, P; Predoi, D

Published: JAN-MAR 2012, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 7, 409, DOI:

Magnetic iron oxide nanoparticles (MION) doped dextran thin films for biomedical applications have been deposited onto the glass substrate by spin coating method. To understand the influence of the MION doping dextran on physico-chemical properties was conducted. The particle concentration in the samples defined as the oxide/dextran mass ratio, R was 1 and 5. MION -dextran thin films were charcacterized by various techniques such as X-ray Photoelectron Spectroscopy (XPS), Glow Discharge Optical Emission Spectroscopy (GDOES), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Attachment (EDAX). These techniques have allowed the structural elucidation of polysaccharides thin films. The second derivative FT-IR spectra showed clearly that the polysaccharides bands. The biocompatibility of the maghemite-dextran thin films was demonstrated using MTT test, with the aid of hFOB 1.19 osteoblats cells. To evaluate cell proliferation rate quantitative by the hFOB 1.19 cells on HAp samples were cultured to 4 days. Cellular morphology was investigated using FESEM to obtain qualitative information of osteoblast cells on MION-dextran thin films. The data stronlgy suggest the potential use of iron oxide-dextran nanocomposite as a poetinal marker for or biomedical applications.

125. Synthesis, Structure, and Luminescent Properties of Europium-Doped Hydroxyapatite Nanocrystalline Powders

Authors: Ciobanu, CS; Iconaru, SL; Massuyeau, F; Constantin, LV; Costescu, A; Predoi, D

Published: 2012, JOURNAL OF NANOMATERIALS, 2012, DOI: 10.1155/2012/942801

The luminescent europium-doped hydroxyapatite (Eu:HAp, Ca10-xEux(PO4)(6)(OH)(2)) with 0 <= x <= 0.2 nanocrystalline powders was synthesized by coprecipitation. The structural, morphological, and textural properties were well characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The vibrational studies were performed by Fourier transform infrared, Raman, and photoluminescence spectroscopies. The X-ray diffraction analysis revealed that hydroxyapatite is the unique crystalline constituent of all the samples, indicating that Eu has been successfully inserted into the HAp lattice. Eu doping inhibits IIAp crystallization, leading to a decrease of the average crystallite size from around 20 nm in the undoped sample to around 7 nm in the sample with the highest Eu concentration. Furthermore, the samples show the characteristic D-5(0) -> F-7(0) transition observed at 578 nm related to Eu3+ ions distributed on Ca2+ sites of the apatitic structure.

126. Assessing toxicity of two types of magnetite nanoparticles in human hepatocarcinoma cells

Authors: Radu, M; Iconaru, SL; Predoi, D; Costache, M; Dinischiotu, A

Published: SEP 2012, FEBS JOURNAL, 279, 205, DOI:

127. Structural and physical properties of antibacterial Ag-doped nano-hydroxyapatite synthesized at 100A degrees C

Authors: Ciobanu, CS; Massuyeau, F; Constantin, LV; Predoi, D

Published: DEC 3 2011, NANOSCALE RESEARCH LETTERS, 6, 8, DOI: 10.1186/1556-276X-6-613

Synthesis of nanosized particle of Ag-doped hydroxyapatite with antibacterial properties is in the great interest in the development of new biomedical applications. In this article, we propose a method for synthesized the Ag-doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100A degrees C in deionized water. Other phase or impurities were not observed. Silver-doped hydroxyapatite nanoparticles (Ag:HAp) were performed by setting the atomic ratio of Ag/[Ag + Ca] at 20% and [Ca + Ag]/P as 1.67. The X-ray diffraction studies demonstrate that powders made by co-precipitation at 100A degrees C exhibit the apatite characteristics with good crystal structure and no new phase or impurity is found. The scanning electron microscopy (SEM) observations suggest that these materials present a little different morphology, which reveals a homogeneous aspect of the synthesized particles for all samples. The presence of calcium (Ca), phosphor (P), oxygen (O), and silver (Ag) in the Ag:HAp is confirmed by energy dispersive X-ray (EDAX) analysis. FT-IR and FT-Raman spectroscopies revealed that the presence of the various vibrational modes corresponds to phosphates and hydroxyl groups. The strain of Staphylococcus aureus was used to evaluate the antibacterial activity of the Ca10-x Ag (x) (PO4)6(OH)2 (x = 0 and 0.2). In vitro bacterial adhesion study indicated a significant difference between HAp (x = 0) and Ag:HAp (x = 0.2). The Ag:Hap nanopowder showed higher inhibition.

128. BET and XRD studies on the hydroxyapatite and europium doped hydroxyapatite

Authors: Ciobanu, CS; Andronescu, E; Predoi, D

Published: JUL 2011, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 13, 824, DOI:

Europium doped hydroxyapatite (Eu:HAp) nanocristalline powders was synthesized by co-precipitation method by setting the atomic ratio of Eu/[Eu + Ca] at 0% and 2% and [Ca+Eu] /P at 1.67. The structural properties were characterized by X-ray diffraction (XRD). Nitrogen adsorption-desorption isotherms were obtained on different samples using BET method. The X-ray diffraction analysis revealed that hydroxyapatite is the unique crystalline constituent of all the samples, indicating that Eu has been successfully inserted into the HAp lattice. Based on N-2 adsorption-desorption isotherms investigation, the pore size, surface area and pore volume of europium doped hydroxyapatite are 16.57 nm, 115.06 m(2)/g and 0.48 cm(3)/g.

129. INFLUENCE OF ANNEALING TREATMENT OF NANO-HYDROXYAPATITE BIOCERAMICS ON THE VIBRATIONAL PROPERTIES

Authors: Ciobanu, CS; Andronescu, E; Stoicu, A; Florea, O; Le Coustumer, P; Galaup, S; Djouadi, A; Mevellec, JY; Musa, I; Massuyeau, F; Prodan, AM; Lafdi, K; Trusca, R; Pasuk, I; Predoi, D

Published: APR-JUN 2011, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 6, 624, DOI:

Nano-hydroxyapatite bio-ceramics were synthesized by sol-gel method. The gel was dried at 80 degrees C for 96 h. The dried gels were individually heated at a rate of 5 degrees C/min up to 600 degrees C, 800 degrees C, and 1000 degrees C. X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used for to characterize the composition, morphology and particle size of samples. At 800 degrees C a small amount of CaO (about 0.3 wt%) was detected in which increased after annealing at 1000 degrees C (about 1.1 wt%). The crystallites are elongated along the c crystallographic axis, but the size anisotropy decreases with increasing temperature above 800 degrees C. The size along the elongation axis increased from 43 nm at 80 degrees C to about 143 nm at 1000 degrees C, as determined by XRD, and from 120 to 280 nm, as measured by TEM. The functional groups were analyzed using Fourier transform infrared (FTIR) and Raman spectroscopies confirming the presence of various and PO43 and OH- bands in the samples. After calcination at 1000 degrees C the bands are more intense which indicates an increase in the cristallynity. The photoluminescence (PL) of HAp treated at various temperatures (80, 600, 800, 1000 degrees C) was also studied. hFOB 1.19 osteoblats cells were used to determine cell proliferation, viability and citotoxicity after interaction with the prepared bioceramics. To evaluate cell proliferation rate quantitative by the hFOB 1.19 cells on HAp samples were cultured to 4 days. Cellular morphology was investigated using FESEM to obtain qualitative information of osteoblast cells on HAp samples. The number of hFOB 1.19 cells on control HAp_80, HAp_600, HAp_800 and HAp_1000 was 400 +/- 30, 360 +/- 25, 350 +/- 21, 320 +/- 16 and 300 +/- 10 after 4 days. Our results proved that the HAp sintered at 1000 degrees C promoted osteoblast cell attachment and adhesion.

130. Characterization of Sucrose Thin Films for Biomedical Applications

Authors: Iconaru, SL; Ungureanu, F; Costescu, A; Costache, M; Dinischiotu, A; Predoi, D

Published: 2011, JOURNAL OF NANOMATERIALS, 2011, DOI: 10.1155/2011/291512

Sucrose is a natural osmolyte accumulated in the cells of organisms as they adapt to environmental stress. In vitro sucrose increases protein stability and forces partially unfolded structures to refold. Thin films of sucrose (C12H22O11) were deposited on thin cut glass substrates by the thermal evaporation technique (P similar to 10(-5) torr). Characteristics of thin films were put into evidence by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), scanning electron microscopy (SEM), and differential thermal analysis and thermal gravimetric analysis (TG/DTA). The experimental results confirm a uniform deposition of an adherent layer. In this paper we present a part of the characteristics of sucrose thin films deposited on glass in medium vacuum conditions, as a part of a culture medium for osteoblast cells. Osteoblast cells were used to determine proliferation, viability, and cytotoxicity interactions with sucrose powder and sucrose thin films. The osteoblast cells have been provided from the American Type Culture Collection (ATCC) Centre. The outcome of this study demonstrated the effectiveness of sucrose thin films as a possible nontoxic agent for biomedical applications.

131. EUROPIUM CONCENTRATION EFFECT OF EUROPIUM DOPED HYDROXYAPATITE ON PROLIFERATION OF OSTEOBLAST CELLS

Authors: Frumosu, F; Iconaru, SL; Predoi, D

Published: OCT-DEC 2011, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 6, 1865, DOI:

The aim of this paper is the preparation and characterization of hydroxyapatite doped with europium (Eu3+, Eu:Hap). The nanopowders were obtained by coprecipitation method and analyzed through infrared spectroscopy (FT-IR) and Fourier transform Raman spectroscopy (FT-Raman). The preliminary results reveal the nanometric dimension of the particles and indicate that Eu3+ has been introduced into the framework of HAp. The Eu concentration effects of nano Eu: HAp were studied on human osteoblast MG 63 cells in vitro. Our results demonstrate that cell proliferation is not related to the Eu concentration in the HAp particles. This work provides an interesting view of the role of nano Eu: HAp as ideal biomedical materials in future clinical applications.

132. BET AND XRD STUDIES ON THE HYDROXYAPATITE AND EUROPIUM DOPED HYDROXYAPATITE

Authors: Ciobanu, CS; Andronescu, E; Predoi, D

Published: JUL-SEP 2011, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 6, 1244, DOI:

133. BIOCOMPATIBILITY STUDY OF EUROPIUM DOPED CRYSTALLINE HYDROXYAPATITE BIOCERAMICS

Authors: Ciobanu, CS; Massuyeau, F; Andronescu, E; Stan, MS; Dinischiotu, A; Predoi, D

Published: OCT-DEC 2011, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 6, 1647, DOI:

For the first time we presented the preliminary results of biocompatibility studies on bioceramic hydroxyapatite powders doped with europium Ca10-xEux(PO4)(6)(OH)(2), with 0.01 <= x(Eu) <= 0.2 prepared at low temperature by a simple coprecipitation approach. The X-ray diffraction (XRD) studies revealed the characteristic peaks of hydroxyapatite in each sample. No evidence for additional crystalline phases was found, proving the complete substitution of Eu in the HAp lattice in the whole range of concentrations. The scanning electron microscopy (SEM) observations suggest that these materials present a little different morphology, which reveals a homogeneous aspect of the synthesized particles for all samples. The PL investigations shown the PL intensity changed considerably by varying the x(Eu). The value of x(Eu) in the hydroxyapatite formula has almost no effect on the wavelength of emission peaks. In order to test Hap_Eu biocompatibility, the effect of europium substituted hydroxyapatite nanocristalline powders with different x(Eu) on cell viability and proliferation of HEK293 cell line were evaluated. The in vitro investigation showed no significant decrease of viability of HEK293 cell line and low levels of intracellular lipid peroxidation in the Hap_Eu treated cells. In conclusion, the results suggest that Eu doped HAp has low toxicity and exhibit a good biocompatibility.

134. Oxidative stress induced by two types of magnetite nanoparticules in HepG(2) cell line

Authors: Radu, M; Predoi, D; Costache, M; Dinischiotu, A

Published: AUG 28 2011, TOXICOLOGY LETTERS, 205, S288, DOI: 10.1016/j.toxlet.2011.05.973

135. Biocompatibility Studies of Iron-oxide-dextrin Thin Films

Authors: Andronescu, E; Costache, M; Ciobanu, CS; Prodan, AM; Predoi, D

Published: OCT 2010, REVISTA DE CHIMIE, 61, 928, DOI:

Dextrin coated magnetic nanoparticles have been obtained by co-precipitation. As a second step biocompatible magnetic thin film has been synthesized from the iron oxide coated with dextrin powders by pulsed laser deposition technique. Biocompatibility tests consisting of osteoblast cells growth, viability and proliferation were monitored on the surface of the thin films. The cells morphology was characterized by scanning electron microscopy (SEM) after 48h.

136. Biomolecular urease thin films grown by laser techniques for blood diagnostic applications

Authors: Gyorgy, E; Sima, F; Mihailescu, IN; Smausz, T; Hopp, B; Predoi, D; Sima, LE; Petrescu, SM

Published: MAY 10 2010, MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS, 30, 541, DOI: 10.1016/j.msec.2010.02.003

Matrix assisted pulsed laser evaporation (MAPLE) was used for growing urease thin films designed for biosensor applications in clinical diagnostics. The targets exposed to laser radiation were made from a frozen composite manufactured by dissolving biomaterials in distilled water. We used a UV KrF* (lambda = 248 nm, tau(FWHM) congruent to 30 ns, nu = 10 Hz) excimer source for multipulse laser irradiation of the frozen targets cooled with Peltier elements. The laser source was operated at an incident fluence of 0.4 J/cm(2). Urease activity and kinetics were assayed by the Worthington method that monitors urea hydrolysis by coupling ammonia production to a glutamate dehydrogenase reaction. A decrease in absorbance was measured at 340 nm and correlated with the enzymatic activity of urease. We show that the urease films obtained by MAPLE techniques remain active up to three months after deposition. (C) 2010 Elsevier B.V. All rights reserved.

137. PRELIMINARY BIOCOMPATIBILITY STUDIES OF HYDROXYAPATITE COATED IRON OXIDE

Authors: Andronescu, E; Ciobanu, CS; Pall, L; Costache, M; Predoi, D

Published: 2010, REVISTA ROMANA DE MATERIALE-ROMANIAN JOURNAL OF MATERIALS, 40, 249, DOI:

Bioceramic composites were obtained by combining two biocompatible components (by example- in our studies - hydroxyapatite and iron oxide nanoparticles). The preparation method determines the particle size and shape, the size distribution, the surface chemistry of the iron oxide particles and consequently their magnetic properties. The samples were analysed by X-ray diffraction and IR spectroscopy. Their thermal behaviour was studied by thermogravimetric and thermodifferential analysis. These characterization techniques confirmed the presence of hydroxyapatite on the magnetite surface. Osteoblast cell cultures were used to determine cell proliferation, viability and cytotoxicity on interaction with the samples. The cultures displayed good in vitro behaviour.

138. Physico-chemical Properties of Iron-oxide-dextrin Thin Films

Authors: Ciobanu, CS; Andronescu, E; Pall, L; Iconaru, SL; Gyorgy, E; Predoi, D

Published: DEC 2010, REVISTA DE CHIMIE, 61, 1211, DOI:

Iron oxide nanoparticles were synthesized in the presence of dextrin. The adsorption process of different dextrin molecules onto the surface of in water dispersed iron-oxide nanoparticles has been investigated to optimize the preparation of iron oxide magnetic fluids. An average iron oxide core size of 8 nm was found by transmission electron microscopy (TEM) for the samples. Scanning electron microscopy (SEM) micro-structural studies revealed a spherical shape of the particles. X-ray phase analysis revealed spinel structure of the iron oxide particles. The attachment of the dextrin on the particle surface was investigated by FTIR spectrometry. The dextrin coated iron oxide nanoparticles were used as targets in Pulsed Laser Deposition (PLD) experiments for thin films synthesis.

139. Looking for new synthesis of hydroxyapatite doped with europium

Authors: Ciobanu, CS; Andronescu, E; Vasile, BS; Valsangiacom, CM; Ghita, RV; Predoi, D

Published: OCT 2010, OPTOELECTRONICS AND ADVANCED MATERIALS-RAPID COMMUNICATIONS, 4, 1519, DOI:

In this work, we synthesized the properties of bioactive nanocrystalline hydroxyapatite (HAp), Ca-10(PO4)(6)(OH)(2) ceramic powder and nanocrystalline HAp doped with europium (III). The europium doped hydroxyapatite with an atomic ratio Eu/(Eu +Ca) between 2% and 20% were synthesized. The structure, morphology and optical properties were characterized by Xray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR). The XRD results reveal that the obtained Eu: HAp shows the characteristic peaks of hydroxyapatite in a hexagonal lattice structure. The results indicated that Eu3+ has been successfully doped into the framework of HAp.

140. PHYSICO-CHEMICAL PROPERTIES OF NANO-SIZED HEXAGONAL HYDROXYAPATITE POWDER SYNTHESIZED BY SOL-GEL

Authors: Costescu, A; Pasuk, I; Ungureanu, F; Dinischiotu, A; Costache, M; Huneau, F; Galaup, S; Le Coustumer, P; Predoi, D

Published: OCT-DEC 2010, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 5, 1000, DOI:

Calcium phosphate ceramic powders were synthesized via sol-gel method. The powders were sintered at 600 and 1000 degrees C and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron microscopy (SEM and TEM), elemental microanalysis (EDS), infrared spectroscopy (FTIR), and thermal analysis (TGA and DTA). The XRD analysis revealed a well crystallized hydroxyapatite (HAp) structure at all temperatures. At 1000 degrees C a small amount of CaO (about 1.2 %) was detected. The average crystallite size increased from 19 nm at 80 degrees C to about 125 nm at 1000 degrees C. FTIR spectra showed the presence of various PO43- and OH- groups present in the powders. In order to verify the biocompatibility of HAP powders with hFOB 1.19 osteoblasts cells, an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test was applied. It was noticed that the ceramics obtained at 1000 degrees C, increased the cell viability with 10%, 40% and 55% after 6, 12 respectively 24 h, whereas that obtained at 600 degrees C was less effective. Our results proved the high biocompatibility of calcium phosphate ceramic powders obtained by sol-gel and sintered at 1000 degrees C.

141. SYNTHESIS AND CHARACTERIZATION OF BIO-COMPATIBLE MAGHEMITE NANOPARTICLES

Authors: Predoi, D; Andronescu, E; Radu, M; Munteanu, MC; Dinischiotu, A

Published: JUL-SEP 2010, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 5, 786, DOI:

The bio-compatible magnetic nanoparticles of maghemite were prepared by a chemical co-precipitation method and dextran was selected as the surfactant to suspend them. By transmission electron microscopy (TEM), the iron oxide nanoparticles appeared nearly spherical with an average diameter of about 8.0 +/- 1 nm. SAED pattern of iron oxide nanoparticles is indexed by a cubic gamma-Fe(2)O(3), the diffraction rings are attributed to the (220), (311), (400), (422), (511) and (440) planes, respectively. Regular fringes are clearly observed in the nanoparticle with a spacing of 0.24 nm, whigh is the (311) interplanar distance of the cubic maghemite. This is in perfect agreement with the X-Ray Diffraction (XRD) results, indicating that the nanoparticles are well crystallyzed in spite of their ultrafine sized. The attachment of the dextran on the particle surface was confirmed by Fourier Transform Infrared (FTIR) Spectroscopy. The biocompatibility of maghemite nanoparticles covered by dextran with HepG2 cells was checked by MTT test. Cell viability was > 98% when the iron concentration was 12.0 mu g iron/ml and 24.0 mu g iron/ml respectively. In conclusion, these nanoparticles presented a good biocompatibility with HepG2 cells, which was proportionally with the dilution level.

142. Synthesis and ultrasonic characterization of hydroxyapatite ceramic powders

Authors: Predoi, D; Derible, S; Duflo, H

Published: JAN 2010, OPTOELECTRONICS AND ADVANCED MATERIALS-RAPID COMMUNICATIONS, 4, 114, DOI:

143. PHYSICO-CHEMICAL STUDIES OF SUCROSE THIN FILMS

Authors: Predoi, D

Published: APR-JUN 2010, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 5, 377, DOI:

Sucrose is a natural osmolyte accumulated in cells of organisms as they adapt to environmental stress. In vitro sucrose increases protein stability and forces partially unfolded structures to refold. Thin films of sucrose (C12H22O11) were deposited on thin cut glass substrates by thermal evaporation technique (p similar to 10(-5) torr). Characteristics of thin films were putted into evidence by Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM) and differential thermal analysis and thermal gravimetric analysis (TG/DTA). The experimental results confirm a uniform deposition of an adherent layer.

144. Characteristics of Vacuum Deposited Sucrose Thin Films

Authors: Ungureanu, F; Predoi, D; Ghita, RV; Vatasescu-Balcan, RA; Costache, M

Published: 2009, INTERFACE CONTROLLED ORGANIC THIN FILMS, 129, 71, DOI: 10.1007/978-3-540-95930-4_11

Thin films of sucrose (C12H22O11) were deposited on thin cut glass substrates by thermal evaporation technique (p similar to 10-5 torr). The surface morphology was putted into evidence by FT-IR and SEM analysis. The experimental results confirm a uniform deposition of an adherent sucrose layer. The biological tests (e.g., cell morphology and cell viability evaluated by measuring mitochondrial dehydrogenise activity with MTT assay) confirm the properties of sucrose thin films as bioactive material. The human fetal osteoblast system grown on thin sucrose film was used for the determination of cell proliferation, cell viability and cell morphology studies.

145. Structural investigations of sol-gel derived silicate gels using Eu3+ ion-probe luminescence

Authors: Secu, CE; Predoi, D; Secu, M; Cernea, M; Aldica, G

Published: SEP 2009, OPTICAL MATERIALS, 31, 1748, DOI: 10.1016/j.optmat.2009.05.009

Undoped and Eu3+-doped CaF2-SiO2 gels were prepared by the sol-gel method and their optical properties have been studied. The UV-VIS-NIR absorption and photoluminescence spectra have shown the bands typical for the Eu3+ ions transitions. When the Eu-doped gel is annealed at temperatures up to 800 degrees C (i.e. above the CaF2 crystallisation peak at similar to 460 degrees C) the photoluminescence spectra intensity increase, the 590 nm (D-5(0) -> F-7(1)) and 620 nm (D-5(0) -> F-7(2)) luminescence bands become comparable and a structuring of the 620 nm band is observed. The phonon sidebands peaks associated with the F-5(0) -> D-7(2) transition of the Eu3+ ion were observed at around 1000 and 620 cm(-1) and have been assigned to the Si-O and Ca-O bonds, respectively. A phonon sideband signal in the range of 3007400 cm(-1) was attributed to Ca-F bonds in the precipitated CaF2 phase. From the optical absorption, photoluminescence and phonon sidebands spectra we have concluded that in the gels annealed at 800 degrees C, the Eu3+ ions are incorporated into the silica network and in the precipitated CaF2 phase. (c) 2009 Elsevier B.V. All rights reserved.

146. Synthesis and ultrasonic characterization of hydroxyapatite ceramic powders

Authors: Predoi, D; Derible, S; Duflo, H

Published: JUN 2009, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 11, 856, DOI:

147. Calcium phosphate ceramics for biomedical applications

Authors: Predoi, D; Vatasescu-Balcan, RA; Pasuk, I; Trusca, R; Costache, M

Published: AUG 2008, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 10, 2155, DOI:

Calcium phosphate compounds have been studied for biomedical applications due to chemical and structural similarity to the mineral phase of bone and tooth. The composition, physico-chemical properties, crystal size and morphology of synthetic apatite are extremely sensitive to preparative conditions and sometimes it resulted into non-stoichiometric calcium deficient hydroxyapatite (HAp) powders. The present paper describes the synthesis of calcium phosphate ceramics powders via a sol-gel method, The powders were sintered at 600 and 800 degrees C. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDXS) were used for characterization and evaluation of the phase composition, morphology and particle size of samples, The functional group of the coatings were analyzed using Fourier transform infrared (FTIR). The XRD analysis revealed a well crystallized HA structure at both temperatures. At 800 degrees C a small amount of CaO (about 0.4%) was detected. The mean crystallite size, determined from the breadth of the diffraction lines, increases from 30 nm at 600 degrees C to about 110 nm at 800 degrees C. FTIR spectra showed the presence of various PO43- and OH- groups present in the powders. Osteoblast cells were used to determine cell proliferation, viability and citotoxicity after interaction with the prepared bioceramics, by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole) assay. We note that the viability of HAp-600 starts to decrease after 12h, while the viability of HAp-800 decreases after 6h.

148. Osteoblast interaction with iron oxide nanoparticles coated with dextrin in cell culture

Authors: Predoi, D; Vatasescu-Balcan, RA

Published: JAN 2008, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 10, 157, DOI:

The iron oxide nanoparticles and iron oxide nanoparticles coated with dextrin have been synthesized using aqueous solution of ferric and ferrous ions and mixtures of dextrin with sodium salt. The size of the iron-oxide nanoparticles are controlled by the concentration of sodium salt in the medium. An average size of iron oxide and iron oxide coated with dextrin was found by transmission electron microscopie (TEM). The iron oxide nanoparticles are nearly spherical with an average diameter of about 8.0 +/- 1 nm. The iron oxide nanoparticles coated with dextrin appear to cluster-like aggregates. The average diameter of these nanoparticles is about 6 1 nm. The attachment of the dextrin on the particle surface was confirmed by FTIR spectroscopy and scanning electron microscopy (SEM). Osteoblasts used to determine the cell proliferation, viability and citotoxicity interaction with iron oxide nanoparticles coated with dextrin has been obtained from the upper part of the patient's femur.

149. Study of iron oxide nanoparticles coated with dextrin obtained by coprecipitation

Authors: Vatasescu-Balcan, RA; Predoi, D; Ungureanu, F; Costache, M

Published: MAR 2008, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 10, 696, DOI:

In this paper we present the preparation and biological tests of iron oxide nanoparticles coated with dextrin. Iron oxide was also prepared by co-precipitation. The samples were characterized by transmission electron microscopy (TEM) and 14 scanning electron microscopy (SEM). Biocompatibility test of the iron oxide nanoparticles coated with dextrin substrate has been done using primary osteoblast cell line. After osteoblast culture achievement, the cells were treated with trypsin 0.05% and splitted in 35/35 mm Petri dish. The influence in vitro was assessed using primary osteoblast cell line and various techniques to observe cell-particles interactions. The results of these analyses are presented in this work.

150. Study of osteoblast interaction with iron oxide nanoparticles coated with dextrin in cell culture

Authors: Vatasescu-Balcan, RA; Predoi, D; Costache, M

Published: JUN 2008, FEBS JOURNAL, 275, 374, DOI:

151. Creatinine biomaterial thin films grown by laser techniques

Authors: Gyorgy, E; Axente, E; Mihailescu, IN; Predoi, D; Ciuca, S; Neamtu, J

Published: MAR 2008, JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE, 19, 1339, DOI: 10.1007/s10856-007-3254-8

Creatinine thin films were synthesised by matrix assisted pulsed laser deposition (PLD) techniques for enzyme-based biosensor applications. An UV KrF* (lambda = 248 nm, tau similar to 10 ns) excimer laser source was used for the irradiation of the targets at incident fluence values in the 0.3-0.5 J/cm(2) range. For the matrix assisted PLD the targets consisted on a frozen composite obtained by dissolving the biomaterials in distilled water. The surface morphology, chemical composition and structure of the obtained biomaterial thin films were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, and electron dispersive X-ray spectroscopy as a function of the target preparation procedure and incident laser fluence.

152. Structural and hydrogen absorption/desorption properties of YNi(4-x)Al(x)Mg compounds (with 0 <= x <= 1.5)

Authors: Stan, C; Andronescu, E; Predoi, D; Bobet, JL

Published: AUG 11 2008, JOURNAL OF ALLOYS AND COMPOUNDS, 461, 234, DOI: 10.1016/j.jallcom.2007.07.064

The compounds YNi(4-x)Al(x)Mg with 0 <= x <= 1.5, crystallizing in the C15 structure type (MgCu(4)Sn-type), have been elaborated by mechanical milling and a subsequent heat treatment at 650 degrees C for 1 h. It was possible to synthesize the compounds YNi(4-x)Al(x)Mg with x up to approximately 1.15 and the lattice parameters was in good agreement with those already reported. All the samples, excepting the YNi(4)Mg compound, absorbed and desorbed hydrogen reversibly and no structural change is reported after the hydrogenation. A direct relationship between the lattice parameters and the equilibrium plateau pressure was found. (C) 2007 Elsevier B.V. All rights reserved.

153. FexOy nanoparticles embedded in sol-gel vitreous silica. The effect of the catalyst nature

Authors: Raileanu, M; Crisan, M; Braileanu, A; Dragan, N; Zaharescu, M; Stan, C; Predoi, D; Kuncser, V; Marinescu, VE; Hodorogea, SM

Published: JAN 15 2008, JOURNAL OF NON-CRYSTALLINE SOLIDS, 354, 631, DOI: 10.1016/j.jnoncrysol.2007.07.070

This work reports on recently investigated structural and magnetic properties of three FexOy-SiO2 nanocomposites prepared by the alkoxide route of the sol-gel method. Depending on the presence or absence of catalyst and on its nature (acidic or basic), important differences among the samples have been observed from the point of view of their structure and properties. (c) 2007 Elsevier B.V. All rights reserved.

154. Iron oxide in a silica matrix prepared by the sol-gel method

Authors: Predoi, D; Crisan, O; Jitianu, A; Valsangiacom, MC; Raileanu, M; Crisan, M; Zaharescu, M

Published: JUN 4 2007, THIN SOLID FILMS, 515, 6323, DOI: 10.1016/j.tsf.2006.11.148

FexOy-SiO2 nanocomposites were prepared by sol-gel method by using two SiO2 sources and Fe(SO4)(2)center dot 7H(2)O as raw materials. The amorphous gels were thermally treated up to 1000 degrees C. The initial gel and the thermally treated samples were characterized by thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA) and infrared spectroscopy. The presence of hematite was confirmed by the obtained Mossbauer spectra which showed the characteristic sextet. The total amount and the size distributions of the hematite nanoparticles can be controlled via the initial precursors and subsequent by annealing conditions. (C) 2006 Elsevier B.V. All rights reserved.

155. Thermal studies of magnetic spinel iron oxide in solution

Authors: Predoi, D; Valsangiacom, CM

Published: JUN 2007, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 9, 1799, DOI:

Small particles of iron - based magnetic spinel oxide are technologically interesting because of their magnetic properties. The synthesis from solution, generally achieved by coprecipitation, offers some advantages: simple and rapid preparation, control of particle size and composition, various possibilities to modify the particle surface state allowing to make homogeneous and stable dispersion in liquid or solid media. This work reports the thermal studies of magnetic iron spinel oxide nanoparticles. For this study, the Fe2+-Fe3+ mixture (Fe2+/Fe3+=0.5) was introduced in an alkaline solutions of which the pH was kept constant. The influence of the particles sizes on the Y -> aFe(2)O(3) transformation is analyzed.

156. Optical characterization of the phosphate glasses containing pair transition ions

Authors: Elisa, M; Grigorescu, C; Vasiliu, I; Bulinski, M; Kuncser, V; Predoi, D; Filoti, G; Meghea, A; Iftimie, N; Giurginca, M; Onose, C

Published: MAR 2007, OPTICAL AND QUANTUM ELECTRONICS, 39, 531, DOI: 10.1007/s11082-007-9097-1

The paper deals with optical and electronic properties of the aluminophosphate glasses containing Fe-Mn and Fe-Cr ion pairs in different concentration. The influence of the mixed alkali ions over the electronic properties has been investigated. The optical behavior (optical transmission) of the glass samples has been studied by UV-VIS spectroscopy and the refractive index dependency on wavelength has been discussed. The transmission spectra show features specific for the doping transition ions (TM), revealing different oxidation states of iron (Fe2+/Fe3+), manganese (Mn2+/Mn3+) and chromium (Cr3+/Cr6+) in the vitreous network. Mossbauer spectroscopy offers information regarding the TM oxidation states, redox processes and the iron coordination symmetry in the vitreous network. In the case of Fe-Mn doped glasses, the percentage of Fe2+ is about 40% and a doubled iron content leads to an increasing of Fe2+ percentage up to 53%. The replacing of lithium ions by natrium ions (mixed alkali effect) provides an increasing of the Fe2+ percentage up to 56%. The occurrence of the tetrahedral or octahedral symmetry of Fe(2+)supercript stop ions bonded by O2- ions depends on the transition ion nature and Li+/Na+ ratio. Infrared absorption spectra of the pair transition ions-doped aluminophosphate glasses reveal optical phonons specific for the phosphate glass matrix.

157. The colloidal route of the sol-gel process - an alternative to produce Fe3O4-SiO2 nanocomposites

Authors: Raileanu, M; Crisan, M; Ballo, A; Cosma, C; Petre, J; Stan, C; Predoi, D; Valsangiacom, CM; Tolea, F; Secu, C

Published: MAY 2007, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 9, 1402, DOI:

The iron oxide-based nanomaterials have a great importance because of their impact on a wide number of industries. They have many properties and applications in domains as: environmental protection, biomedical, catalysis, information displays and electronics. In order to avoid the tendency of nanoparticles to aggregate, they are often included in sol-gel derived silica matrices, thus being also ensured a homogeneous dispersion of the ultra-fine metal oxide particles in the host matrix. The reasons of the attempt are both an economic and a non-pollutant one, tacking into account the fact that it is well known that aqueous silica sol is cheaper and less toxic than TEOS. The Fe3O4 was introduced in the reaction mixture as aqueous suspension. A final iron content related to SiO2 of 3% wt. was chosen for the prepared nanocomposite. Thermal analysis, IR spectroscopy, XRD and TEM methods have been used for the structural characterisation,. Some experiments of water depollution (from As) have been proceeded using the prepared Fe3O4-SiO2 nanocomposite.

158. High temperature thermolumineseence of BaFCl : EU2+ X-ray storage phosphor

Authors: Secu, CE; Secu, M; Predoi, D

Published: 2007, PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 4, NO 3, 4, +, DOI: 10.1002/pssc.200673736

Thermoluminescence (TL) of Eu2+-doped BaFCl polycrystalline powders X- ray irradiated at room temperature show several TL peaks at 364 K, 408 K, 470 K, 524 K and 646 K. Thermally activated recombination processes responsible for TL have been studied using complementary techniques as TL and its bleaching, diffuse reflectance, X-ray excited luminescence (XL) and photostimulated luminescence (PSL). Experimental results indicate that F(Cr) centres are the dominant electron trap centres, the Eu2+-trapped hole aggregate centres playing the role of recombination centres. The 470 K and 646 K TSL glow peaks are assigned to the recombination inside the triple aggregates (Eu2+ - hole centre - F(Cl-) centre). The remaining 408 K and 524 K TL peaks are tentatively assigned to recombination between F centres and double aggregates (Eu2+ - hole centre). (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

159. Structural and magnetic properties of FexOy nanoparticles dispersed in silica matrix

Authors: Predoi, D; Clerac, R; Raileanu, M; Crisan, M; Zaharescu, M

Published: MAY 2007, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 9, 1498, DOI:

Some FexOy-SiO2 composites were prepared by the colloidal and alkoxidic route of the sol-gel method. The dried gels were thermally treated and the samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared absorption (IR) spectroscopy, magnetic susceptibility measurements and Mossbauer spectroscopy. Nanoparticles of gamma and /or alpha iron oxide phase of different size were obtained in the silica matrix depending on the gelation conditions and on the thermal treatment. It was observed that the particle sizes and the thermal stability of the iron oxide phases strongly depend on the preparation method. At temperatures above 400 degrees C, the gamma-phase begins to transform to the alpha-phase.

160. A study on iron oxide nanoparticles coated with dextrin obtained by coprecipitation

Authors: Predoi, D

Published: MAR 2007, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 2, 173, DOI:

The iron oxide nanoparticles and iron oxide nanoparticles coated with dextrin have been synthesized using aqueous solution of ferric and ferrous ions and mixtures of dextrin with sodium salt. The size of the iron-oxide nanoparticles is controlled by the concentration of sodium salt in the medium. An average size of iron oxide and iron oxide coated with dextrin was found by transmission electron microscopy (TEM). The iron oxide nanoparticles are nearly spherical with an average diameter of about 8.0 +/- 1 nm. The iron oxide nanoparticles coated with dextrin appear as cluster-like aggregates. The average diameter of these nanoparticles is about 5.1 nm. The attachment of the dextrin on the particle surface was confirmed by FTIR spectroscopy and thermogravimetric analyses (TGA).

161. Hydroxyapatite-iron oxide bioceramic prepared using nano-size powders

Authors: Predoi, D; Barsan, M; Andronescu, E; Vatasescu-Balcan, RA; Costache, M

Published: NOV 2007, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 9, 3613, DOI:

The hydroxyapatite (HAp) is an important material for orthopedics and dentistry applications. In the present study a simple method was tried for added the iron oxide nanoparticles into HAp so as to establish and induce a biocompatibility. In the research the mechanism of the coated of iron oxide with HAp would also be described by the analysis of X-ray diffractometer, scanning electron microscope and Fourier transformation infrared. Osteoblast cells were permanent monitored to detect any possible influence due to samples that might alter the cell growth, viability and proliferation.

162. IR and thermal studies of iron oxide nanoparticles in a bioceramic matrix

Authors: Birsan, C; Predoi, D; Andronescu, E

Published: JUN 2007, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 9, 1824, DOI:

Magnetic iron oxide nanoparticles have a great potential in various applications in biomedical research and technology. Iron oxide particles such as magnetite (Fe3O4) is by far the most commonly employed magnetic materials for biomedical applications. Bioceramic composites were obtained by combining the magnetite with two biocompatible components (hydroxyapatite and bioglass). Their thermal behaviour has been studied by thermal analysis (DTA and TG). The interaction of iron oxide with the bioceramic matrix has been investigated using IR spectroscopy.

163. Time-resolved luminescence spectroscopy of Eu2+ in BaFCl : Eu2+ X-ray storage phosphor

Authors: Secu, M; Secu, CE; Vasile, V; Predoi, D; Gazdaru, DM

Published: JUN 2007, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 9, 1802, DOI:

Photoluminescence (PL) spectra recorded at room temperature (RT) in polycrystalline BaFCI:Eu2+ X-ray storage phosphor have shown the europium associated luminescences, a broad luminescence band at 385nm (3.22eV) with a 3.3 +/- 0.1 mu s PL lifetime accompanied by a luminescence line at about 368nm (3.37eV). The energy difference Delta EB-L =226cm(-1) between the two excited levels from which the europium associated band and line luminescences took place was computed. An additional broad luminescence band at about 425nm (2.92eV) with 0.7 +/- 0.1 mu s PL lifetime has been attributed to the europium luminescence perturbed by an impurity. Time resolved spectroscopy measurements have shown that no other impurity luminescences (like oxygen-vacancy centres) can be observed at RT except the europium associated ones.

164. Characterisation of magnetic iron oxide in hydroxyapatite

Authors: Birsan, M; Predoi, D; Birsan, C; Secu, CE; Andronescu, F

Published: JUN 2007, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 9, 1832, DOI:

In order to be used for medical applications, a material must exhibit many specific characteristics, of which the most fundamental is related to biocompatibility. Lately, the iron oxide nanoparticles are preferred for biomedical applications because they present a superparamagnetic behaviour at room temperature. The preparation method and conditions of iron oxide nanoparticles represents some of the most important challenges that will determine the particle size and shape, the size distribution, the surface chemistry of the particles and consequently their magnetic properties. The samples were characterized by X-ray diffractions (XRD), transmission electron microscopy (TEM) and infrared spectroscopy.

165. Characteristics of hydroxyapatite thin films

Authors: Predoi, D; Ghita, RV; Ungureanu, F; Negrila, CC; Vatasescu-Balcan, RA; Costache, M

Published: DEC 2007, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 9, 3831, DOI:

Thin films of hydroxyapatite (HAp) (Ca-10(PO4)(6)(OH)(2)) were vacuum deposited on different substrates (quartz and silver) in connection with biomedical applications. Characteristics of thin films were putted into evidence by (SEM) and (XPS) analysis. The FT-IR spectroscopy was performed on hydroxyapatite powder and thin films deposited on quartz. The deposition of HAp thin films presents good surface quality as a smooth and an adherent layer. The biological tests confirm the characteristics of these thin films as bioactive materials. The hydroxyapatite thin films supports have a micro cell configuration that allows them to be used for obtaining medical biocompatible supports.

166. FexOy-SiO2 nanocomposites studied by Mossbauer spectroscopy

Authors: Predoi, D; Kuncser, V; Zaharescu, M; Jitianu, A; Crisan, M; Keune, W; Sahoo, B; Filoti, G; Raileanu, M

Published: APR 2006, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 8, 522, DOI:

FexOy-SiO2 nanocomposites were obtained via the sol-gel method, by using three different precursors for the silica matrix. The morphology and the iron phase composition is strongly influenced by the precursors. The presence of magnetically ordered goethite and fayalite is evidenced by low temperature Mossbauer spectroscopy. Subsequent annealing treatments performed on the initial samples have induced the formation of hematite nanoparticles in the silica matrix, mainly on the account of the goethite decomposition. The total amount and the size distribution of the hematite nanoparticles can be controlled via the initial precursors and the subsequent annealing conditions. The simultaneous analysis of the iron phase composition and of the local magnetic interactions in the analysed samples is performed.

167. Fe3O4-SiO2 nanocomposites obtained via alkoxide and colloidal route

Authors: Jitianu, A; Raileanu, M; Crisan, M; Predoi, D; Jitianu, M; Stanciu, L; Zaharescu, M

Published: DEC 2006, JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY, 40, 323, DOI: 10.1007/s10971-006-9321-7

The magnetic nanocomposite materials represent an important class of nanomaterials extensively studied nowadays due to their varied applications from medical diagnostic to storage information. The iron oxides in silica matrix systems are highly investigated. The sol-gel method is a suitable way of preparation of Fe3O4-SiO2 nanocomposite materials, since this method allowed the preparation of nanocomposite materials with narrow size distribution of magnetite in silica matrix. In the present work, nanocomposite materials in the Fe3O4-SiO2 system were prepared by sol-gel method via alkoxide and aqueous route. As SiO2 sources, tetraethoxysilan (TEOS) for the alkoxide route, as well as silica sol Ludox (30%) for the aqueous route, were used. This study shows the influence of the type of silica matrix on the structure, size, and distribution of the Fe3O4 nanoparticles in the Fe3O4-SiO2 systems. The gels were annealed at 550 degrees C in order to consolidate the matrices. The structural characterization of the obtained materials via the two preparation routes was performed by DTA/TGA analysis, X-ray diffraction, IR and Mossbauer spectroscopy, Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction (SAED).

168. Giant magnetoresistive coatings using thermionic vacuum are technology

Authors: Anghel, A; Luncu, CP; Mustata, I; Zaroschi, V; Lungu. AM; Barbu, I; Badulescu, M; Pompilian, O; Schinteie, G; Predoi, D; Kunkser, V; Filoti, G; Apetroaei, N

Published: 2006, CZECHOSLOVAK JOURNAL OF PHYSICS, 56, B23, DOI: 10.1007/s10582-006-0173-8

Giant magnetoresistive (GMR) coatings on silicon, glass and Kapton were prepared by simultaneous thermionic vacuum are (TVA) discharges in high vacuum conditions. The magnetic metal or alloy (Fe, Co, Ni, Permalloy) together with the noble non magnetic metal were deposited on substrates having different positions relative to the discharges. Local magnetic interactions and Fe-phase composition were obtained by Mossbauer spectroscopy whereas the magnetoresistance effects were measured by a dc method using a four-point configuration with perpendicular to plane magnetic fields up to 0.8 T. The surface morphology of the coatings was characterized by atomic force microscopy (AFM) in contact mode.

169. Micro-structure and magnetic properties of Fe-Cu nanocomposites for anisotropic permanent magnets

Authors: Kuncser, V; Valeanu, M; Lifei, F; Predoi, D; Jianu, A; Kappel, W; Codescu, M; Patroi, E; Pasuk, I; Bulinski, M; Filoti, G

Published: MAY 31 2005, JOURNAL OF ALLOYS AND COMPOUNDS, 395, 6, DOI: 10.1016/j.jallcom.2004.11.059

Melt spun ribbons of FexCu100-x were obtained by different procedures, in order to maximize the dispersion of the Fe atoms in the Cu matrix. Subsequent thermal and mechanical treatments were used for a controlled crystallization process of the soft magnetic phase. A detailed analysis of structural aspects and crystallization dynamics and their relation with the magnetic behavior of the Fe-Cu ribbons has been obtained via Mossbauer spectroscopy, X-ray diffraction (XRD) and magnetic measurements. In order to obtain composite permanent magnets with shape anisotropy, the optimal conditions and the suitable processing were established. &COPY; 2004 Elsevier B.V. All rights reserved.

170. Optical and electronic properties of the aluminophosphate glasses doped with 3d-transition metal ions

Authors: Elisa, M; Grigorescu, CEA; Vasiliu, C; Bulinski, M; Kuncser, V; Predoi, D; Filoti, G; Meghea, A; Iftimie, N; Giurginca, M

Published: OCT 2005, REVIEWS ON ADVANCED MATERIALS SCIENCE, 10, 374, DOI:

Aluminophosphate glasses doped with Fe, Mn, and Cr have been obtained by a wet non-conventional method. Structural information was provided by IR absorption spectra in the range 2000-500 cm(-1). The optical behaviour (transmission and refractive index) of the samples has been studied by UV-VIS-NIR spectroscopy. The Fe valence state and the local coordination were also analysed via Fe-57 Mossbauer spectroscopy, whose data revealed the redox equilibrium in the Fe-doped glasses according to the redox potentials of the transition ions.

171. Reply to comment on 'magnetic relaxation phenomena and inter-particle interactions in nanosized gamma-Fe2O3 systems'

Authors: Predoi, D; Kuncser, V; Filoti, G

Published: APR 6 2005, JOURNAL OF PHYSICS-CONDENSED MATTER, 17, 2254, DOI: 10.1088/0953-8984/17/13/N02

172. Structural and magnetic properties of iron species/SiO2 nanocomposites obtained by sol-gel methods

Authors: Predoi, D; Kuncser, V; Zaharescu, M; Keune, W; Sahoo, B; Valeanu, M; Crisan, M; Raileanu, M; Jitianu, A; Filoti, G

Published: 2004, SECOND SEEHEIM CONFERENCE ON MAGNETISM, PROCEEDINGS, 3510, DOI:

The phase composition, local structure and magnetic interactions were investigated in FexOx-SiO2 nanocomposites obtained by modern sol-gel methods. The very sensitive method of Mossbauer spectroscopy has evidenced the strong influence of the silica matrix precursor on the iron phase composition in the initial composites as well as on the size distribution of the hematite nanoparticles obtained by suitable thermal annealing treatments.

173. Magnetic interactions and spin structure in composite Fe/Nd2Fe14B systems

Authors: Kuncser, V; Valeanu, M; Lifei, F; Predoi, D; Palade, P; Schinteie, G; Crisan, O; Filoti, G

Published: MAY 2004, JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 272, 799, DOI: 10.1016/j.jmmm.2003.12.1279

Local magnetic interactions and spin configurations in alpha-Fe/Nd2Fe14B composite exchange-spring magnets have been investigated by Mossbauer spectroscopy and the magnetic behaviour was analysed by magnetometry. A new method for the evaluation of the coupling strength between soft and hard magnetic phases is proposed. (C) 2003 Elsevier B.V. All rights reserved.

174. FexCu1-x alloys for permanent magnets

Authors: Kappel, W; Codescu, MM; Pasuk, I; Patroi, E; Kuncser, V; Valeanu, M; Predoi, D; Filoti, G

Published: SEP 2004, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 6, 978, DOI:

New magnetic composite materials, ribbon samples, with nominal compositions FexCu1-x (x=0.2; 0.5; 0.8) were obtained by the melt spinning technique. Various information was provided via X-ray diffraction, Mossbauer and magnetic measurements. The structural aspects: phase composition, size and texture effects, have been corroborated with magnetic properties. Finally, the possibility to choose the adequate composition and the suitable processing in order to obtain desired anisotropic magnetic materials were presented.

175. Magnetic properties of gamma-Fe2O3 nanoparticles

Authors: Predoi, D; Kuncser, V; Nogues, M; Tronc, E; Jolive, JP; Filoti, G; Schinteie, G

Published: MAR 2003, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 5, 216, DOI:

The gamma-Fe2O3 nanoparticles with different surface states are investigated by X-ray Diffraction, Electron Microscopy, Differential Thermal Analysis and magnetic: measurements in low applied field. The influence of the adsorbed species (H2O and sulphate complexes) on the inter-particle magnetic interactions is analysed in relation to both the magnetic states of the surface and the inter-particle distance.

176. THE EFFECT OF HYDROXYAPATITE AND IRONE OXIDE NANOPARTICLES ON MAIZE AND WINTER WHEAT PLANTS

Authors: Petcu, E; Lazar, C; Predoi, D; Cimpeanu, C; Predoi, G; Bartha, S; Vlad, IA; Partal, E

Published: , SCIENTIFIC PAPERS-SERIES A-AGRONOMY, 2021, 519, DOI:

Dr. Daniela PREDOI

Scientific Researcher I

Publications

1. Sodium bicarbonate-hydroxyapatite used for removal of lead ions from aqueous solution

2. New Physico-Chemical Analysis of Magnesium-Doped Hydroxyapatite in Dextran Matrix Nanocomposites

3. Morphological and fractal features of cancer cells anchored on composite layers based on magnesium-doped hydroxyapatite loaded in chitosan matrix

4. Hydroxyapatite Nanopowders for Effective Removal of Strontium Ions from Aqueous Solutions

5. Salvia officinalis-Hydroxyapatite Nanocomposites with Antibacterial Properties

6. Influence of the Biological Medium on the Properties of Magnesium Doped Hydroxyapatite Composite Coatings

7. In Vitro and In Vivo Biological Assays of Dextran Coated Iron Oxide Aqueous Magnetic Fluids

8. Biological Response of Human Gingival Fibroblasts to Zinc-Doped Hydroxyapatite Designed for Dental Applications-An In Vitro Study

9. Complex Evaluation of Nanocomposite-Based Hydroxyapatite for Biomedical Applications

10. Development of Novel Tetracycline and Ciprofloxacin Loaded Silver Doped Hydroxyapatite Suspensions for Biomedical Applications

11. New Insights into the Biological Response Triggered by Dextran-Coated Maghemite Nanoparticles in Pancreatic Cancer Cells and Their Potential for Theranostic Applications

12. Response of the Endogenous Antioxidant Defense System Induced in RAW 264.7 Macrophages upon Exposure to Dextran-Coated Iron Oxide Nanoparticles

13. Biocomposite Coatings Doped with Magnesium and Zinc Ions in Chitosan Matrix for Antimicrobial Applications

14. Dextran-Coated Iron Oxide Nanoparticles Loaded with 5-Fluorouracil for Drug-Delivery Applications

15. Studies of New Layer Formation on the Surface of Zinc Doped Hydroxyapatite/Chitosan Composite Coatings in Biological Medium

16. Studies of the Tarragon Essential Oil Effects on the Characteristics of Doped Hydroxyapatite/Chitosan Biocomposites

17. Novel Dextran Coated Cerium Doped Hydroxyapatite Thin Films

18. Development of Silver Doped Hydroxyapatite Thin Films for Biomedical Applications

19. Impact of Gamma Irradiation on the Properties of Magnesium-Doped Hydroxyapatite in Chitosan Matrix

20. Physicochemical Characterization of Europium-Doped Hydroxyapatite Thin Films with Antifungal Activity

21. The Effects of Electron Beam Irradiation on the Morphological and Physicochemical Properties of Magnesium-Doped Hydroxyapatite/Chitosan Composite Coatings

22. Physicochemical and Biological Evaluation of Chitosan-Coated Magnesium-Doped Hydroxyapatite Composite Layers Obtained by Vacuum Deposition

23. Iron-Oxide-Nanoparticles-Doped Polyaniline Composite Thin Films

24. Fabrication and Physico-Chemical Properties of Antifungal Samarium Doped Hydroxyapatite Thin Films

25. Investigation of Spin Coating Cerium-Doped Hydroxyapatite Thin Films with Antifungal Properties

26. Fabrication of Novel Chitosan-Hydroxyapatite Nanostructured Thin Films for Biomedical Applications

27. Multi-Level Evaluation of UV Action upon Vitamin D Enhanced, Silver Doped Hydroxyapatite Thin Films Deposited on Titanium Substrate

28. Nitrogen and Bromide Co-Doped Hydroxyapatite Thin Films with Antimicrobial Properties

29. Biocompatibility and Antibiofilm Properties of Samarium Doped Hydroxyapatite Coatings: An In Vitro Study

30. THE EFFECT OF HYDROXYAPATITE AND IRONE OXIDE NANOPARTICLES ON MAIZE AND WINTER WHEAT PLANTS

31. Preparation and Characterization of Dextran Coated Iron Oxide Nanoparticles Thin Layers

32. The Physico-Chemical Properties and Exploratory Real-Time Cell Analysis of Hydroxyapatite Nanopowders Substituted with Ce, Mg, Sr, and Zn (0.5-5 at.%)

33. Development of Iron-Doped Hydroxyapatite Coatings

34. TiO2 nanoparticles coated with bio-inspired ligands for the safer-by-design development of photocatalytic paints

35. Removal and Oxidation of As(III) from Water Using Iron Oxide Coated CTAB as Adsorbent

36. Multifunctional Hydroxyapatite Coated with Arthemisia absinthium Composites

37. Development of Cerium-Doped Hydroxyapatite Coatings with Antimicrobial Properties for Biomedical Applications

38. Dextran-Thyme Magnesium-Doped Hydroxyapatite Composite Antimicrobial Coatings

39. Obtaining and Characterizing Thin Layers of Magnesium Doped Hydroxyapatite by Dip Coating Procedure

40. Antimicrobial Properties of Samarium Doped Hydroxyapatite Suspensions and Coatings

41. Physico-Chemical Properties and In Vitro Antifungal Evaluation of Samarium Doped Hydroxyapatite Coatings

42. Chitosan-Hydroxyapatite Composite Layers Generated in Radio Frequency Magnetron Sputtering Discharge: From Plasma to Structural and Morphological Analysis of Layers

43. Fabrication of Silver- and Zinc-Doped Hydroxyapatite Coatings for Enhancing Antimicrobial Effect

44. Silver-Doped Hydroxyapatite Thin Layers Obtained by Sol-Gel Spin Coating Procedure

45. Peppermint Essential Oil-Doped Hydroxyapatite Nanoparticles with Antimicrobial Properties

46. The Effect of the Ionizing Radiation on Hydroxyapatite-Polydimethylsiloxane Layers

47. Preparations of Silver/Montmorillonite Biocomposite Multilayers and Their Antifungal Activity

48. Biocompatible Layers Obtained from Functionalized Iron Oxide Nanoparticles in Suspension

49. Photoluminescent Hydroxylapatite: Eu3+ Doping Effect on Biological Behaviour

50. Synthesis, Characterization, and Antimicrobial Activity of Magnesium-Doped Hydroxyapatite Suspensions

51. Zinc Doped Hydroxyapatite Thin Films Prepared by Sol-Gel Spin Coating Procedure

52. Evaluation of Antibacterial Activity of Zinc-Doped Hydroxyapatite Colloids and Dispersion Stability Using Ultrasounds

53. Dextran-Coated Zinc-Doped Hydroxyapatite for Biomedical Applications

54. Study of the Structure and Antimicrobial Activity of Ca-Deficient Ceramics on Chlorhexidine Nanoclay Substrate

55. Commercial Hydroxyapatite Powders for Lead Removal from Aqueous Solution

56. Antimicrobial Studies on Iron Oxide-Dextran Colloidal Suspension

57. Physico-Chemical Characteristics and Antimicrobial Studies of Silver Doped Hydroxyapatite

58. Properties of Basil and Lavender Essential Oils Adsorbed on the Surface of Hydroxyapatite

59. Bioceramic Layers with Antifungal Properties

60. Removal of Zinc Ions Using Hydroxyapatite and Study of Ultrasound Behavior of Aqueous Media

61. Influence of Ionizing Radiations on Structural and Antibacterial Properties of Hydroxyapatite-Polydimethylsiloxane Layers

62. Application of Biocompatible Magnetite Nanoparticles for the Removal of Arsenic and Copper from Water

63. Adsorption of Pb (II) Ions onto Hydroxyapatite Nanopowders in Aqueous Solutions

64. Antimicrobial Activity of New Materials Based on Lavender and Basil Essential Oils and Hydroxyapatite

65. Development of Zinc-Doped Hydroxyapatite by Sol-Gel Method for Medical Applications

66. ANALYSIS of Pdge-BASED CONTACT on N-Gasb

67. ZnHAp Thin Films for Medical Applications

68. Structural Characterization and Antifungal Studies of Zinc-Doped Hydroxyapatite Coatings

69. Advances in Functionalized Materials Research 2016

70. Textural, Structural and Biological Evaluation of Hydroxyapatite Doped with Zinc at Low Concentrations

71. Ultrasound studies on magnetic fluids based on maghemite nanoparticles

72. Ultrasonic Measurements on Cyclodextrin/Hydroxyapatite Composites for Potential Water Depollution

73. Physicochemical and antimicrobial properties of silver-doped hydroxyapatite collagen biocomposite

74. Synthesis, Characterization, and Toxicity Evaluation of Dextran-Coated Iron Oxide Nanoparticles

75. The tolerability of dextran-coated iron oxide nanoparticles during in vivo observation of the rats

76. Structural and Biological Assessment of Zinc Doped Hydroxyapatite Nanoparticles

77. Carbon Nanotubes-Hydroxyapatite Nanocomposites for an Improved Osteoblast Cell Response