Evaluation of the Toxicity of Zinc Oxide Nanoparticles upon Staphylococcus Aureus and Escherichia Coliin Contaminated water

Background: Nanoparticles (NPs) have recently attracted extensive attention in the field of elimination and reduction of microbial load in various water resources. Accordingly, this study aimed to eliminate bacterial contamination from aqueous solutions using synthesized NPs.Methods: In the present study, zinc oxide (ZnO) and silver (Ag) ion-doped zinc oxide (Ag/ZnO, 1-6 wt%) nanoparticles were synthesized using the sol-gel process and then characterized in terms of structure, morphology, and antimicrobial activity. X-ray diffraction (XRD) was utilized to determine the nanoparticle size and crystal structure. Images from field emission-scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) confirmed the successful production of NPs. The antimicrobial activity of ZnO and Ag1-6%/ZnO against Staphylococcus aureus and Escherichia coli was assessed by the agar well diffusion method.Results: According to the findings, the synthesized ZnO had a hexagonal structure and the size of ZnO and Ag5%/ZnO were 32.56 nm and 12.81 nm, respectively; the field emission-scanning electron microscopy (FE-SEM) images showed that the nanoparticle sizes were 77.60 nm and 47.15 nm, respectively. Based on transmission electron microscopy (TEM) images, the mean size of ZnO and Ag5%/ZnO was 22.5 nm and 17.5 nm, respectively. The results showed that the diameter of the zone of inhibition created by Ag5%/ZnO at a concentration of 0.1 g/mL was 20 mm and 13 mm for S. aureus  and E. coli, respectively.Conclusion: The results indicated that E. coli was more resistant than S. aureus, although E. coli was still more resistant at low concentrations.