| Abstract | Zinc oxide nanoparticles (ZnO NPs) are promising antimicrobial agents due to their broad-spectrum antibacterial activity and low production cost. Despite many studies demonstrating the effectiveness of ZnO NPs, the antibacterial mechanism is still unknown. Previous work has implicated the role of reactive oxygen species, physical damage of the cell envelope, and/or release of toxic Zn2+ ions as possible mechanisms of action. Assays utilizing S. aureus mutant strains ¿katA and ¿mprF demonstrated that hydrogen peroxide and electrostatic interactions are not crucial for mediating ZnO NP toxicity. Instead, we find Zn2+ accumulation mediates toxicity independent of physical contact. Through this, we conclude that soluble Zn2+ is the primary mechanism by which ZnO NPs mediate toxicity in Mueller-Hinton Broth. Future work investigating the effect of ZnO NP synthesis methods on Zn2+ dissolution could allow for the synthesis of ZnO NPs that possess chemical and morphological properties best suited for antibacterial efficacy. |
