Evaluating the Antibacterial Potential of Distinct Size Populations of Stabilized Zinc Nanoparticles

Engineered nanoparticles are precisely synthesized to exploit unique properties conferred by their small size and high surface area for environmental, biomedical, and agricultural applications. While these physical properties dictate functionality, they can also have various intended and unintended implications for biological systems. Both the particle size and shape influence cellular uptake. Because of zinc's antibacterial properties and role as a plant micronutrient, polyvinylpyrrolidone stabilized zinc nanoparticles (ZnNP) were selected for this study. Four synthesis methods were tested to produce distinct size populations of polymer-coated ZnNP, and all utilized water as the solvent to promote sustainable, green chemistry. The antibacterial activity of ZnNP was assessed in two agriculturally relevant bacteria strains: Escherichia coli and Bacillus cereus. To further examine the effects of ZnNP on bacterial cells, reactive oxygen species (ROS) generation was measured via hydrogen peroxide (H₂O₂) production. The bacteria's incubation temperature was also altered to assess bacterial growth and susceptibility after exposure to ZnNP. The ZnNP from the smaller size population inhibited the most growth across bacterial strains, assays, and incubation temperatures. Increased antibacterial effects and ROS production were observed after incubation at a higher temperature. These results indicate that the deliberately designed nanoparticles are potentially valuable in microbial control and offer promising solutions for the future of healthy agricultural systems.