No abstract

The antibacterial activity of various nanoparticles is gaining increasing interest due to its potential medical applications. In this work, we presented the synthesis of copper oxide nanoparticles prepared by chemical reduction from aqueous solutions of copper sulfate (CuSO 4) with sodium borohydride (NaBH 4) and hydrazine hydrate (N 2 H 4) as reductant and polyvinylpyrrolidone (PVP) as stabilizer. The X-ray diffraction spectra showed the formation of tenorite (CuO) and cuprite (Cu 2 O) nanoparticles when different ratios of CuSO 4 /NaBH 4 and CuSO 4 /N 2 H 4 were used. Photographs obtained by transmission electron microscopy (TEM) showed agglomerates of grains with a narrow size distribution (from 20 to 70 nm), whereas the radii of the individual particles were between 2 and 20 nm. Smaller nanoparticles and narrower particle size distributions were obtained when NaBH 4 was used. The results of antibacterial activity using the Kirby-Bauer method showed that nanoparticles obtained with NaBH 4 presented a reasonable bactericidal activity. Pseudomonas aureginosa and Staphylococcus aureus were more susceptible to the particle size than Escherichia coli. In addition, with small amounts of Cu 2 O in samples of CuO nanoparticles, the antibacterial susceptibility against Pseudomonas aureginosa was improved. Finally, nanoparticles of CuO incorporated into cotton by applying ultrasound waves remained impregnated after five washes.

Nanopowdered alloys of Pd100−xFex, with x=4, 6, 8, and 12, have been prepared by ultrasound assisted electrochemistry. The composition of the individual particles, as determined by x-ray fluorescence, and the bulk composition, as determined by atomic absorption, are in agreement within experimental error. Transmission electron microscopy indicates that the nanopowders consist of agglomerates of small grains with a radius of approximately 5 nm, a radius which is confirmed by the broadening of the reflections in the x-ray powder diffraction patterns. X-ray fluorescence analysis of individual grains indicates a homogeneous distribution of palladium and iron throughout the grains. The x-ray diffraction patterns indicate that solid solutions of iron in palladium show no evidence of any pure palladium, any pure iron, or any other PdFe compound. The 78 K iron-57 Mössbauer spectra of these nanopowders reveal the presence of one magnetic sextet assigned to slowly relaxing superparamagnetic particles of Pd100−xFex and one weak doublet, which is assigned to rapidly relaxing superparamagnetic particles of Pd100−xFex. The hyperfine fields of 29.0 to 31.0 T are typical of iron in a metallic alloy and correspond to a magnetic moment of approximately 2 μB per iron atom. The hysteresis curves obtained at 4.2, 100, and 295 K with a vibrating sample magnetometer are typical of superparamagnetic particles with saturation magnetization values which are substantially smaller than those observed for the bulk. The fit of the magnetization curves with a Langevin function yields estimates of the particle radii which are in good agreement with those obtained both by transmission electron microscopy and by the broadening of the x-ray diffraction peaks.

Stable zinc oxide nanoparticles were prepared by chemical process. Zinc oxide nanoparticles were synthesized using a modified method with zinc nitrate and sodium hydroxide at 60° C. The synthesized nanopowders were characterized in terms of chemical composition (EDS), structure FTIR and XRD, particle size and morphology by TEM. The XRD results confirm that ZnO nanoparticles were obtained with hexagonal arrangement (Wurtzite). The nanoparticles showed sizes between 10 to 30 nm and semispherical forms. The luminescent properties of the synthesized nanoparticles were measured in a photoluminescence assay on a Raman instrument. The samples were irradiated with two laser beams of different wavelengths. The application of the fingerprints on different surfaces was done using deferments surfaces.

The bactericidal properties of copper oxide nanoparticles have growing interest due to potential application in the medical area. The present research investigates the influence of sodium dodecyl sulfate (SDS) and poly­(vinylpyrrolidone) (PVP) on the production of copper oxide nanoparticles prepared from copper sulfate (CuSO4) and sodium borohydride (NaBH4) solutions. Different analytical techniques were used to determine the crystal nature, mean size diameter, and surface morphology of the copper oxide nanoparticles. The X-ray diffraction (XRD) patterns showed formation of nanoparticles of cuprite (Cu2O) and tenorite (CuO) when PVP and SDS were added at the beginning of the reaction. In fact, when the Cu/PVP ratio was 1.62, Cu2O nanoparticles were obtained. In addition, nanoparticles of CuO were synthesized when the Cu/PVP ratios were 0.54 and 0.81. On the other hand, a mixture of copper oxides (CuO and Cu2O) and cuprite (Cu2O) was obtained when PVP (Cu/PVP = 0.81 and 1.62) and SDS (Cu/SDS = 0.90) were added 30 min after the beginning of the reaction. Transmission electron microscopy (TEM) images show agglomerated nanoparticles with a size distribution ranging from 2 to 60 nm, while individual particles have sizes between 4.1 ± 1.9 and 41.6 ± 12.8 nm. The Kirby–Bauer method for the determination of antibacterial activity shows that small CuO (4.1 ± 1.9 nm) and Cu2O (8.5 ± 5.3 nm) nanoparticles inhibit the growth of Escherichia coli, Staphylococcus aureus MRSA, S. aureus and Pseudomonas aeruginosa bacteria. The antibacterial test of cotton fabric impregnated with nanoparticles shows positive results. The determination of the optimal ratio of copper oxide nanoparticles per cm2 of fabric that are able to exhibit a good antibacterial activity is ongoing.