Synthesis and characterization of zinc and copper oxide nanoparticles and their antibacteria activity

Inorganic nano-metal oxides can be effective alternatives to drug resistant organic antibiotics due to their broad spectrum antimicrobial activity against pathogenic and mutagenic gram-negative and positive bacteria. In this study, zinc and copper oxides (ZnO and CuO) were synthesised using a wet chemical reduction method. The oxide nanoparticles were characterized using X-ray diffraction (XRD), UV–Vis spectrometer, Fourier Transformed Infra-red spectrometer and Transmission electron microscopy (TEM). The antibacterial activities of the nanoparticles were investigated against e. coli and s. aureus using disk diffusion and microdilution tests. The TEM micrographs showed that copper oxide nanoparticles assumed a nanorod shape of average length of 100 nm whiles zinc oxide nanoparticles were spherical of average diameter of 15 nm. The FTIR results showed that the nanoparticles were free of impurities and organic surfactants, which was confirmed by XRD. For the antibacteria tests, the minimum inhibition concentration (MIC) of CuO against e. coli and s. aureus were 1 mg/ml and 0.25 mg/ml respectively whiles it was 0.1 mg/ml for ZnO against s. aureus with ZnO producing no inhibition against e. coli. With the microdilution test, both nanoparticles exhibited activity against both bacterias at all varying concentrations. The results concluded that CuO had higher antibacteria activity compared to ZnO.