National Institute Of Materials Physics - Romania

Cotton fabrics were coated with arrays of ZnO hexagonal prisms using an electroless (catalytic/auto-catalytic) deposition process. A typical three step method, similar to those used for electroless deposition of metals on insulating substrates, consisting of pre-activation, activation and deposition steps was employed. The low-dimensional ZnO particles were grown from an aqueous solution containing zinc nitrate as source of zinc ions and dimethylamineborane as reducing agent. The as-obtained ZnO-coated cotton fabrics were characterized from the point of view of structure by X-ray diffraction (XRD) and morphology by scanning electron microscopy (SEM). The XRD studies demonstrate that the ZnO particles have a hexagonal wurtzite crystalline structure. The SEM observations prove that the cotton fibers are homogeneously covered by hexagonal prisms which have uniform base size of approximately 500 nm and height of 1 mu m. Optical spectroscopy measurements show that the functionalization with ZnO strongly decreases the transmittance in the UV vis region of the cotton fabrics. An important characteristic is that the ZnO-functionalized cotton fabrics exhibit superhydrophobicity, with water contact angles exceeding 150 degrees. The technique described is highly reproducible, easy scalable and cheap, allowing a wide range of applications. (C) 2012 Elsevier B.V. All rights reserved.

A simple approach to fabricate periodic arrays of ring bumps, disk and convex bumps or holes on silicon and gallium arsenide substrates is reported. In the process, a mono or double layer of 700 nm diameter silica colloidal particles were self-assembled on the substrates and a single pulse from a 200 fs laser at 387 nm wavelength was applied. The surfaces were irradiated at normal incidence by immersing the substrates in a glass container filled with acetone, carbon tetrachloride and 1,1,2-trichlor-trifluorethan liquid precursors. The influence of the medium on the near-field interactions for both substrates is investigated. (C) 2012 Elsevier B.V. All rights reserved.

ZnO uniform films were deposited on polymer sphere arrays by an electroless technique. The low-dimensional ZnO particles were grown from an aqueous solution of zinc nitrate and dimethylamineborane. The X-ray diffraction studies demonstrate that the ZnO crystallites have a hexagonal wurtzite structure. The scanning electron microscopy images prove that ZnO hexagonal prisms are synthesized with a fairly uniform diameter of around 200 nm. From the contact angle measurements it was found that the electroless deposition on polymer sphere arrays of semiconductor hexagonal prisms leads to an improvement of ZnO hydrophobic properties.

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.

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.

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.

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.

We report the film deposition of Poly(D, L-lactide-co-glycolide) (PLGA) particle systems by matrix assisted pulsed laser evaporation (MAPLE) technique. PLGA+polyvinyl alcohol (PVA), PLGA+PVA+ bovine serum albumin (BSA) and PLGA+PVA+chitosan (CH) nanoparticles were prepared by an oil-in-water emulsion-diffusion-evaporation method. The average diameter of PLGA particles was between 180-250 nm. The coatings were obtained by laser evaporation of frozen targets prepared by mixing appropriate PLGA aqueous suspensions and dimethyl sulfoxide (DMSO) in three ratios. Depending on the DMSO content, we deposited PLGA particles embedded into polymeric layer mainly obtained due to the entirely or partially dissolving of nanoparticles into the initial solution. In vitro results showed that the distribution and morphology of osteoblast-like SaOs-2 cells on some PLGA particle coatings were similar with that of the positive control. The purpose of this study was to develop layers of PLGA particles for local controlled drug delivery.

In this paper we show that preparation of Ag doped hydroxyapatite by an adapted co-precipitation method at 100 C has several advantages over other techniques. Specifically, it can generate highly crystalline nanopowder Ag:HAp which could be used for implantable medical devices. The XRD of HAp (x(Ag) = 0) and Ag:HAp (x(Ag) = 0.05, and x(Ag) = 0.4) also demonstrates that powders obtained by co-precipitation at 100 C exhibit the apatite characteristics with good crystal structure and no new phase or impurity is found. The SEM results suggested that Ag+ doping had little influence on the morphology and dimension of the samples. It can be seen that all the samples consist of elipsoidal particles. The antibactericidal activity of Ag:HAp-NPs with x(Ag) = 0, x(Ag) = 0.05, and x(Ag) = 0.4 on Bacilus and E.coli ESBL 1576 were presented. The Ag:HAp-NPs with x(Ag) = 0.05, and x(Ag) = 0.4 inhibited the biofilm development both by the gram-positive (Staphylococcus aureus 0364) and the gram-negative (Providencia stuartii 1116) strains. On the other hand, our studies have shown that Ag:HAp with x(Ag) = 0 had no antibacterial activity against gram-positive and gram-negative bacteria.

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.