National Institute Of Materials Physics - Romania

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.

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.

Super paramagnetic iron oxide nanoparticles such as maghemite have been shown to exhibit antimicrobial properties [1-5]. Moreover, the iron oxide nanoparticles have been proposed as a potential magnetically controllable antimicrobial agent which could be directed to a specific infection [3-5]. The present research has focused on studies of the surface and structure of iron oxide dextran (D-IO) composite layers surface and structure. These composite layers were deposited on Si substrates. The structure of iron oxide dextran composite layers was investigated by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) while the surface morphology was evaluated by Scanning Electron Microscopy (SEM). The structural characterizations of the iron oxide dextran composite layers revealed the basic constituents of both iron and dextran structure. Furthermore, the in vitro evaluation of the antifungal effect of the complex layers, which have been shown revealed to be active against C. albicans cells at distinct intervals of time, is exhibited. Our research came to confirm the fungicidal effect of iron oxide dextran composite layers. Also, our results suggest that iron oxide dextran surface may be used for medical treatment of biofilm associated Candida infections.

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.

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.

Ceramic thin films belonging to SiO2-P2O5-CaO-MgO-ZnO-CaF2 system were obtained by combining the sol-gel approach with the spin coating technique. Titanium plates were employed as substrates. The deposited coatings were characterized in terms of composition, structure and morphology with the help of the following methods: X-ray diffraction, Fourier - transform infrared spectroscopy and scanning electron microscopy coupled with energy - dispersive X-ray spectroscopy. In order to assess the bioactivity of a potential metallic implant covered with such layers, the samples were immersed in simulated body fluid for 14 days and their surface was investigated. The results showed that the thin films calcined at a lower temperature have a better biological response due to the vitroceramic nature.

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.

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.

Magnetic nanoparticles embedded in the active layer of the Organic Light Emitting Diodes (OLEDs) significantly increases the electroluminescence and the charge transport without influencing the transparency of these devices. A brief comparison was done in order to identify which parameter influences these properties, by comparing the CoFe2O4 magnetic nanoparticles with CoFe2 metallic magnetic nanoparticles, the latter one being obtained by thermal reduction in hydrogen of cobalt ferrite nanoparticles. CoFe2 have shown a better efficiency of the metallic nanoparticles where probably the main advantage is the higher magnetization property instead of the coercive field. Concerning the charge transport across the OLEDs, these nanoparticles reduce the electron injection, acting as filling traps, which directly increases the electroluminescence and the current at the same voltage.

Morphology is a key element in the functionality of low dimensional structures including here electroactive polymers, especially when applications such as muscle like actuators are sought. The reason is that morphology in the context of a high specific surface object strongly influences specific parameters such as ionic diffusion, conductivity and consequently the actuation capability of the system. In the present work a new architecture for microtube-based actuating elements is presented. Free-standing fibrillar microtubes with diameter in the range of micrometers and with a core-shell polyaniline/gold structure are fabricated through a scalable approach. Aligned electrospun poly(methyl methacrylate) fibers are coated with gold and are further employed as microstructured electrodes for the electrochemical deposition of polyaniline. Further the poly(methyl methacrylate) core was dissolved, leading to a tubular structure. The polyaniline/gold microtubes show complex, rapid and reversible movement patterns, with great stability and consistency over repeated actuation cycles. Thus, when the potential is swept between -0.2 and 1 V at different rates, the microtubes move, this movement being associated with the morphological and structural characteristics of the deposited polyaniline layer, a mechanism based on the expansion/contraction and conformational changes of the polymer chains due to the insertion/expulsion of ions. The response time of these electroactive microstructures during one cycle is in the range of seconds, a consequence of their low dimensionality and specific structure. Moreover the actuation takes place in different electrolytes including simulated gastric fluid, which enables a wide range of applications. (C) 2017 Elsevier B.V. All rights reserved.