Search

Nanocrystalline ZnO particles were prepared from ethanolic solutions of zinc acetate by forced hydrolysis, at a low temperature. The fresh prepared ZnO nanoparticles were coated with gentamicin. The nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermal analysis (TG-DSC). The electronic (UV-Vis), infrared (FTIR) and photoluminescence (PL) spectra were also recorded. The biological activity tests such as minimum inhibitory concentration (MIC) and disk diffusion were performed in Mueller-Hinton broth using different concentrations of ZnO and ZnO-gentamicin hybrid nanoparticles, by a standard microbial method on Enterococcus faecalis, Salmonella, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes. The bacteriological tests indicate a synergic activity of ZnO-gentamicin nanoparticles. The release rate of gentamicin was monitored photometrically with UV-Vis spectrometer. [ABSTRACT FROM AUTHOR]

Nanocrystalline ZnO particles doped with Mn(II) ions were prepared by a forced hydrolysis method of zinc acetate dihydrate and manganese acetate tetrahydrate, under reflux, in buthanol. The precipitate obtained was separated by centrifugation at 9.000 rpm and purified by refluxing in water. The dopant percentage was 1, 2.5 and 5%. The qualitative composition of the nanopowder has been evidenced in the elemental EDS maps. Optical investigation shows that the Mn doping in ZnO lattice leads to a decrease in the near band edge position due to the introduction of new unoccupied states by Mn 3d electrons. The luminescence of ZnO is quenched by increasing the dopant ions percentage. At doping rate of 1% Mn in the ZnO lattice a tenfold decrease in intensity of luminescence was observed, along with modification of the luminescence pattern. Further increases of dopant percent from 1% to 5% had as result a decrease of only 30% in the luminescence intensity. The photocatalytic activity was investigated against methylene blue. The increase of Mn percentage leads to a better photocatalytic activity. [ABSTRACT FROM AUTHOR]

Nanocrystalline ZnO particles were prepared from methanolic solutions of zinc acetate dihydrate without using base such as NaOH or LiOH through a colloid process carried out at a low temperature of 60oC. The precipitate obtained after 12-72h contained ZnO, covered with polymeric species of zinc hydroxo acetate. The reaction course was studied by mass spectrometry means. To complete the hydrolysis process, up to pure ZnO, it was necessarily to reflux the white precipitate separate from methanolic solution, in water at 80oC. We found that reaction time in the presence of methanol primarily influenced the size of the particles, while the reaction time in the presence of water mainly influenced the ZnO purity. [ABSTRACT FROM AUTHOR]

Magnetic (nano)particles are intensively studied in the last years due to their multiple applications. The purpose of this paper is the synthesis of rod-like magnetite by magnetically assisted co-precipitation. The synthesized magnetite nanoparticles were characterized by XRD, DSC-TG and TEM from compositional and especially morphological point of view. The use of 0.5T magnetic field induces a preferential growth of magnetite nanoparticles on the 400 direction while this preferential growth cannot be identified in the absence of the magnetic field proving that the synthesis of rod-like magnetite is due to the applied magnetic field. The mechanism of synthesis was explained based on the magnetite particles behaviour in magnetic field. [ABSTRACT FROM AUTHOR]

Using this system as active compound carrier, the anti-bacterial activity of the Fe3O4/oleic acid/cephalosporins nanoparticles (core/shell/adsorption-shell) on S. aureus and E. coli was tested. The dimensions of Fe3O4 nanoparticles were in the 5-20 nm range and they were characterized by High Resolution Transmision Electron Microscopy. The antibacterial activity was observed in both, reference Fe3O4/oleic acid shell nanoparticles and adsorption shell cephalosporins case. These nanofluids may be used in drug delivery systems. [ABSTRACT FROM AUTHOR]

This work represents a preliminary study about the Cytotoxicity of (non)magnetic nanoparticles. Antibiograms with nanostructured powder were performed. (Non)magnetic nanoparticles based on C-Fe, C-Cu, C-Al and C-C, were synthesized by plasma processing and analyzed with High-Resolution Transmission Electron Microscopy (HR-TEM). The difusimetric method was used to prove the bacteriostatic activity. This method is easy to perform and allows for obtaining of specific information related to germ sensitivity. Two reference germs were used: Staphylococcus Aureus ATCC 25923 and Escherichia Coli ATCC 25922. Comparing the inhibition zones, it was found that the cytotoxicity effect is related to (non)magnetic nanoparticles. [ABSTRACT FROM AUTHOR]