ZnO Nanoparticles as an Antibacterial Agent Against E. coli

Abstract

In the present work, we studied the particle size dependant antibacterial activity of zinc oxide (ZnO) nanoparticles (NPs) against Escherichia coli (E. coli) K-12 bacterial strain. ZnO particles of varying sizes were prepared via wet chemical route using zinc acetate as a precursor and lithium hydroxide as a reducing agent. X-ray diffraction measurement revealed hexagonal wurtzite structure of as synthesized ZnO NPs and the particle size was calculated by using Scherer's formula. The optical density measurement shows blue shift in λmax of optical spectra with decreasing particle size and corresponding Tauc plot demonstrates increasing band gap in small size ZnO NPs. Minimum inhibitory concentration (MIC) measurements and growth kinetics studies were carried out to measure the antibacterial activity of ZnO NPs on E. coli. The enhanced bacterial growth inhibition by small sized ZnO NPs is attributed to their inherent ability of generating reactive oxygen species owing to their high surface area and large number of surface defects.