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

Abstract

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
• toxicity

Acknowledgments

This work was partially supported by the Korea Ministry of Environment (MOE) as part of “The advancement of scientific research and technological development in environmental science program (2016000140006)”. Prof Jong-Wha Jung and Minjun Kim, PhD candidate, kindly provided ZnO nanoparticles.

Disclosure

The authors report no conflicts of interest in this work.