Photocatalytic antibacterial application of zinc oxide nanoparticles and self-assembled networks under dual UV irradiation for enhanced disinfection

Su-Eon Jin,1 Jun Eon Jin,2 Woochul Hwang,3 Seok Won Hong4 1Research Institute for Medical Sciences, College of Medicine, Inha University, Incheon 22212, Korea; 2College of Electrical Engineering, Korea University, Seoul 02841, Korea; 3ECOSET Co., Ltd., Ansan 15610, Korea; 4Korea Institute of Science and Technology, Seoul 02792, Korea Background: Zinc oxide (ZnO) nanoparticles and their networks have been developed for use in various applications such as gas sensors and semiconductors. Aim: In this study, their antibacterial activity against Escherichia coli under dual ultraviolet (UV) irradiation for disinfection was investigated. Materials and methods: ZnO nanoparticles were synthesized and immobilized onto silicon (Si) wafers by self-assembly. The physicochemical properties and antibacterial activity of ZnO nanoparticles and their networks were evaluated. Gene ontology was analyzed and toxicity levels were also monitored. Results: Synthesized ZnO nanoparticles were spherical nanocrystals (<100 nm; Zn, 47%; O,53%) that formed macro-mesoporous three-dimensional nanostructures on Si wafers in a concentration-dependent manner. ZnO nanoparticles and their networks on Si wafers had an excellent antibacterial activity against E. coli under dual UV irradiation (>3log CFU/ml). Specifically, arrayed ZnO nanoparticle networks showed superior activity compared with free synthesized ZnO nanoparticles. Oxidative stress-responsive proteins in E. coli were identified and categorized, which indicated antibacterial activity. Synthesized ZnO nanoparticles were less cytotoxic in HaCaT with an IC50 of 6.632 mg/mL, but phototoxic in Balb/c 3T3. Conclusion: The results suggested that ZnO nanoparticles and their networks can be promising photocatalytic antibiotics for use in next-generation disinfection systems. Their application could also be extended to industrial and clinical use as effective and safe photocatalytic antibiotics. Keywords: zinc oxide nanoparticles, immobilization, dual UV, antibacterial, disinfection, toxicit