Background: Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe 2 O 3 nanoparticles against Gram-positive and Gram-negative bacteria. Methods and results: Nanosized particles of three metal oxides (ZnO, CuO, and Fe 2 O 3 ) were synthesized by a sol-gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe 2 O 3 , respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Conclusion: Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe 2 O 3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO . CuO . Fe 2 O 3 .

If we define Pp, as follows then Eq. A-3 could be rewritten as v,But the species extent of reaction, E, is defined as e = l -y By substituting for y in A-6 using A-5 and solving for P,,, we obtain Thus, Pp, will be equal to the traditional "fraction of unreacted species" (1 -E) when there is no volume change or dilution of initial electrolyte tank volume. Conceptually, pPu is proportional to (1 -e) where the constant of proportionality is the extent of dilution resulting from water transport. This performance criteria should not be confused with (1 -e). REFERENCES 1. D. T. Hobbs, in Electrochemistry for a Cleaner Environment, J. D. Genders and N. L. Weinberg, Editors, The

Background: CuO is one of the most important transition metal oxides due to its captivating properties. It is used in various technological applications such as high critical temperature superconductors, gas sensors, in photoconductive applications, and so on. Recently, it has been used as an antimicrobial agent against various bacterial species. Here we synthesized different sized CuO nanoparticles and explored the size-dependent antibacterial activity of each CuO nanoparticles preparation. Methods: CuO nanoparticles were synthesized using a gel combustion method. In this approach, cupric nitrate trihydrate and citric acid were dissolved in distilled water with a molar ratio of 1:1. The resulting solution was stirred at 100°C, until gel was formed. The gel was allowed to burn at 200°C to obtain amorphous powder, which was further annealed at different temperatures to obtain different size CuO nanoparticles. We then tested the antibacterial properties using well diffusion, minimum inhibitory concentration, and minimum bactericidal concentration methods. Results: XRD spectra confirmed the formation of single phase CuO nanoparticles. Crystallite size was found to increase with an increase in annealing temperature due to atomic diffusion. A minimum crystallite size of 20 nm was observed in the case of CuO nanoparticles annealed at 400°C. Transmission electron microscopy results corroborate well with XRD results. All CuO nanoparticles exhibited inhibitory effects against both Gram-positive and -negative bacteria. The size of the particles was correlated with its antibacterial activity. Conclusion: The antibacterial activity of CuO nanoparticles was found to be size-dependent. In addition, the highly stable minimum-sized monodispersed copper oxide nanoparticles synthesized during this study demonstrated a significant increase in antibacterial activities against both Gram-positive and -negative bacterial strains.

No abstract

No abstract