National Institute Of Materials Physics - Romania

Publications

articles found
21. 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.
22. 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.
23. Effects of Solvent Additive and Micro-Patterned Substrate on the Properties of Thin Films Based on P3HT:PC70BM Blends Deposited by MAPLE
Authors: Socol, M; Preda, N; Breazu, C; Petre, G; Stanculescu, A; Stavarache, I; Popescu-Pelin, G; Stochioiu, A; Socol, G; Iftimie, S; Thanner, C; Rasoga, O

Published: JAN 2023, MATERIALS, 16, 144, DOI: 10.3390/ma16010144

Lately, there is a growing interest in organic photovoltaic (OPV) cells due to the organic materials' properties and compatibility with various types of substrates. However, their efficiencies are low relative to the silicon ones; therefore, other ways (i.e., electrode micron/nanostructuring, synthesis of new organic materials, use of additives) to improve their performances are still being sought. In this context, we studied the behavior of the common organic bulk heterojunction (P3HT:PC70BM) deposited by matrix-assisted pulsed laser evaporation (MAPLE) with/without 0.3% of 1,8-diiodooctane (DIO) additive on flat and micro-patterned ITO substrates. The obtained results showed that in the MAPLE process, a small quantity of additive can modify the morphology of the organic films and decrease their roughness. Besides the use of the additive, the micro-patterning of the electrode leads to a greater increase in the absorption of the studied photovoltaic structures. The inferred values of the filling factors for the measured cells in ambient conditions range from 19% for the photovoltaic structures with no additive and without substrate patterning to 27% for the counterpart structures with patterning and a small quantity of additive.
24. 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.
25. COMPARATIVE STUDY ON TiO2 NANOPARTICLES OBTAINED BY PRECIPITATION AND SOL-GEL
Authors: Alecu, AE; Girjoaba, SA; Enculescu, MM; Busuioc, C

Published: 2023, UNIVERSITY POLITEHNICA OF BUCHAREST SCIENTIFIC BULLETIN SERIES B-CHEMISTRY AND MATERIALS SCIENCE, 85, DOI:

The purpose of the work is the synthesis and characterization of TiO2 nanoparticles. These were obtained by two different methods, precipitation and sol-gel, starting from titanium(IV) isopropoxide and calcining at 500 degrees C for 2 h. The compositional, structural, morphological and optical properties of the resulting powders were investigated by energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, reflectance spectroscopy and photoluminescence spectroscopy. The thermally treated samples contain TiO2 as single phase with tetragonal structure, known as anatase. SEM analysis showed quasi-spherical particles with a diameter of few nanometres for the calcined samples, while the optical studies revealed band gap values of 3.04 and 3.17 eV, as a function of the preparation route.
26. Structural and transport properties of Cu2CoSnS4 films prepared by spray pyrolysis
Authors: El Khouja, O; Assahsahi, I; Nouneh, K; Touhami, ME; Secu, M; Talbi, A; Khaaissa, Y; Matei, E; Stancu, V; Galatanu, A; Galca, AC

Published: NOV 1 2022, CERAMICS INTERNATIONAL, 48, DOI: 10.1016/j.ceramint.2022.07.185

In the present work, stannite Cu2CoSnS4 (CCTS) films were elaborated using spray pyrolysis method on soda-lime glass, at different deposition temperatures (T-d = 250, 300, and 350 degrees C), followed by different chosen sulfurization temperatures (T-s = 450, 500, and 550 degrees C). X-ray diffraction (XRD) revealed the nearly single-phase formation of CCTS films at 300 degrees C deposition temperature. After sulfurization in argon flow, the XRD lines become narrower, the average crystallite size expanding above 70 nm. The Raman spectroscopy analysis confirmed the stannite structure formation, as well as the presence CoS2 secondary phases, which reduces at higher sulfurization temperature (550 degrees C). The energy dispersive spectroscopy results indicated atomic ratios of Cu/Co/Sn/S close to the ideal stoichiometric ratio 2:1:1:4. The room temperature photoluminescence emission is recorded with maximum in the 1.35-1.40 eV range. Thermoelectric properties are measured up to 130 degrees C, the films show poor power factor as a result of small positive Seebeck coefficients 10-45 Of K -1 and low electrical conductivity despite of having relatively high carrier concentration (similar to 10(20) cm(-3)).
27. Layered SnSe nanoflakes with anharmonic phonon properties and memristive characteristics
Authors: Buruiana, AT; Bocirnea, AE; Kuncser, AC; Tite, T; Matei, E; Mihai, C; Zawadzka, N; Olkowska-Pucko, K; Kipczak, L; Babinski, A; Molas, MR; Velea, A; Galca, AC

Published: OCT 15 2022, APPLIED SURFACE SCIENCE, 599, 153983, DOI: 10.1016/j.apsusc.2022.153983

Understanding the phonon anharmonicity and temperature-dependent behavior of phonons that affect the thermal transport properties in 2D materials is crucial for developing efficient thermoelectric and memristor devices. SnSe has attracted significant interest because of its potential applications for developing such novel devices. Here, orthorhombic SnSe nanoflakes with a thickness of less than 100 nm and oriented along the [100] crystal axis were obtained using physical vapor transport at atmospheric pressure. Polarization-resolved Raman spectroscopy of SnSe nanoflakes was performed at a temperature of 5 K. Temperature-dependent frequencies and linewidths of Raman modes in tin selenide were fitted according to the anharmonic phonon coupling theory. The results indicate that both two and three order processes are responsible for the phonon decay in tin selenide. The memristive property was confirmed by electrical measurements of SnSe devices. SnSe memristors have an operating current of 10-4 A, similar to other transition-metal dichalcogenide memristors, but are more energy efficient than memristors based on defect migration, with a threshold voltage of 3 V.
28. Chemical sensing and actuation properties of polypyrrole coated fibers
Authors: Beregoi, M; Beaumont, S; Jinga, SI; Otero, TF; Enculescu, I

Published: OCT 1 2022, SMART MATERIALS AND STRUCTURES, 31, 105012, DOI: 10.1088/1361-665X/ac83ff

Designing complex electrochemical artificial muscles aims towards novel devices which besides excellent actuation capabilities should also present the ability to self-sense the modification of environmental parameters. In order to improve efficiency, mimicking the structure of natural muscles, synthetic actuators should have a similar fibrillary morphology. The importance of using materials based on fiber building blocks in actuators aimed at soft robotics field was demonstrated in the present report by comparing a fibrillary artificial muscle with one based on a classical film structure. Nylon electrospun fiber meshes and films were covered in the same conditions with a thin polypyrrole (PPy) layer. The fibrillary electrospun web morphology mimics that of natural muscles and the structure performs a fast, ample bending movement in liquid electrolyte when switching an applied electric potential between -0.6 and +0.6 V. Using the same actuation conditions, no movement of a film based artificial muscle was observed. In order to check the sensing ability of both fibrillary and film like electroactive architectures, their response i.e. PPy reaction when potential cycles were applied in different concentrations of LiClO4 electrolyte were recorded. The obtained results suggest that the ion exchange of the fibrillary artificial muscle is more efficient due to its higher active surface and such devices could work also as dual device (sensor/artificial muscle).
29. Charge transport mechanisms in free-standing devices with electrospun electrodes
Authors: Ciobotaru, IC; Polosan, S; Enculescu, M; Nitescu, A; Enculescu, I; Beregoi, M; Ciobotaru, CC

Published: SEP 24 2022, NANOTECHNOLOGY, 33, 395203, DOI: 10.1088/1361-6528/ac7ac1

Embedding electronic and optoelectronic devices in common, daily use objects is a fast developing field of research. New architectures are needed for migrating from the classic wafer- based substrates. Novel types of flexible PMMA/Au/Alq(3)/LiF/Al structures were obtained starting from electrospun polymer fibers. Thus, using an electrospinning process poly (methyl metacrylate) (PMMA) nanofibers were fabricated. A thin Au layer deposition rendered the fiber array conductive, this being further employed as the anode. The next steps consisted of the thermal evaporation of tris(8-hydroxyquinolinato) aluminum (Alq(3)) and aluminum deposition as the cathode. The Au covered PMMA nanofiber layer had a similar behavior with an indium tin oxide film i.e. low sheet resistance 10.6 omega/sq and high transparency. The low electrode resistivities allow an electron drift mobility of about 10(-6) cm(2) V-1 s(-1) at a low applied field, similar to the counterpart structures based on thin films. Concerning the relaxation processes in these structures, the Cole-Cole plots exhibit a slightly deformed semicircle, indicating a more complex equivalent circuit for the processes between metal electrodes and the active layer. This equivalent circuit includes reactance equivalent processes at the anode, cathode, in the active layer and most probably originates from the roughness of the metallic electrodes.
30. Electrochemical characterization of shikonin and in-situ evaluation of interaction with DNA
Authors: Leote, RJB; Sanz, CG; Diculescu, VC

Published: SEP 15 2022, JOURNAL OF ELECTROANALYTICAL CHEMISTRY, 921, 116663, DOI: 10.1016/j.jelechem.2022.116663

Shikonin, a natural compound with pharmaceutical properties, has attracted interest due to its anti-oxidant properties, potential anti-cancer activity and activity over several biological pathways, such as dsDNA transcription/replication of cancer cells and inhibition of pyruvate kinase M2. The electrochemical behavior of shikonin in aqueous media was investigated at glassy carbon electrodes by cyclic and differential pulse voltammetry. The reduction involves the quinone moiety and formation of a semiquinone intermediate. In the absence of dissolved oxygen, the reduction is reversible while in normal atmosphere leads to formation of superoxide cation. The oxidation occurs at the dihydroxy moiety and reversibility was only observed in acid electrolytes. A redox mechanism was proposed. The interaction between shikonin and dsDNA was evaluated in incubated solutions and in situ with the dsDNA-electrochemical biosensor. The mechanism of interaction is time-dependent and follows an initial binding step at the grooves of the double strand leading to conformational modifications recognized through the variation of guanine and adenine oxidation peaks. The in-situ electrochemical production of the semiquinone intermediate leads to a preferential interaction with guanine residues, promoting their oxidation and consequently occurrence 8-oxo-guanine. An interaction mechanism was proposed.

Back to top

Copyright © 2023 National Institute of Materials Physics. All Rights Reserved