Anti-Bacterial Activities of Green Synthesized ZnO and CuO Nanoparticles from Leaf Extracts of Warburgia ugandensis

Abstract

This work reports for the first time the green synthesis of zinc oxide nanoparticles (ZnO NPs) and copper oxide nanoparticles (CuO NPs) using leaf extracts of Warburgia ugandensis as encapsulating, stabilizing, and reducing agent. The green method of synthesis proved easy and less costly. The methanolic extracts contained various secondary metabolites as analyzed using gas chromatography-mass spectrometer (GC-MS). The nanoparticles (NPs) were further characterized for the confirmation of their synthesis using various techniques. Ultra violet-Visible spectrometer (UV-vis) confirmed the successful synthesis of ZnO NPs and CuO NPs with a maximum peak at 367 nm and 307.5 nm, respectively. The X-ray diffractometer (XRD) results confirmed the formation of hexagonal wurtzite ZnO NPs and monoclinic structures of CuO NPs with an average size of 21.2 nm and 12.86 nm, respectively. In addition, the Fourier transform infrared (FTIR) analysis showed the presence of various functional groups responsible for the formation of the nanoparticles. The antibacterial activity of the formulated nanoparticles was also investigated against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacterial strains with ZOI (Zones of Inhibition) measured in mm. The green synthesized ZnO nanoparticles using Warburgia ugandensis leaf extracts significantly revealed higher anti-bacterial potentials against E. coli (9.6 ± 0.9 mm) compared to both CuO NPs and ampicillin. This shows that they can be applied in the field of medicine to develop antibacterial agents to treat various ailments.