Curious Case of Bactericidal Action of ZnO

Abstract

ZnO nanoparticles (NPs) are well known for their bactericidal properties. Various mechanisms are proposed for their bactericidal activity. An ambiguity still prevails to know which mechanism or property is mainly influencing the bactericidal activity of ZnO NPs. The antibacterial properties of ZnO NPs were investigated against both Gram-positive and Gram-negative bacteria. Different ZnO samples with different degrees of surface oxygen vacancies were prepared from ZnO2. The surface oxygen vacancy and thereby reactive oxygen species (ROS) production in aqueous ZnO solution are quantified by photoluminescence (PL) and electron paramagnetic resonance (EPR) spin trapping experiments, respectively. Systematic experiments have been performed to validate a precise antibacterial mechanism of ZnO particle.