The use of metal oxide nanoparticles, particularly ZnO nanoparticles (NPs), is expected to continue growing tremendously in manufacturing various products for both industrial purposes and consumer uses. Such applications include, but are not limited to, medicine, water treatment, disinfection, energy, agriculture, and even food. Water scarcity is a well-known global issue, as is the presence of drug-resistant bacteria, which are impervious to most medical treatments; both issues are challenges faced globally. Motivated by the growing global challenge and elevated concerns regarding antibacterial-resistant bacteria being present in drinking water across the U.S., we have conducted an examination of the antibacterial effect and toxicity mechanisms of ZnO NPs. The evaluation and assessment have shown that while the toxicity increase of ZnO NPs on <i>E. coli</i> was proportional to concentrations and exposure time, the antibacterial effect was more significant at the bacterial growth phase (log phase) than at the stationary phase. There also appeared to be a correlation between the physicochemical properties and toxicity as indicated by toxicity effect (growth inhibition rate) of industrial ZnO, extracted ZnO from sunscreen, and commercially available ZnO in that the highest toxicity observed was from industrial ZnO (the smallest particle size among three types of ZnO) with higher ROS accumulation over time compared to the other types of ZnO NPs, especially at the bacterial growth phase (log phase). The cytotoxicity caused by ZnO NPs also resulted in significant morphological changes through destruction of bacterial cells; these changes are mainly considered to have been caused by ROS release. Our findings offer ways to minimize or eliminate the presence of antibiotic resistant bacteria in water, specifically through the antibacterial effects of ZnO NPs. This transformative study is not only timely, but also a critical response to the global emergency of protecting public health and the environment by applying antimicrobial metal oxide nanoparticles.<br/> <br/>

Factors affecting the antibacterial effects of industrial and sunscreen derived ZnO nanoparticles and their toxicity mechanisms

254th National Meeting (2017)

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