Surface antibacterial properties and mechanism of NiCo2O4 against E. Coli

Abstract

Bacterial infections seriously affect and threaten human health. Antibacterial agents, including inorganic metal-based materials, have widely been explored owing to their effective properties in killing pathogens. Among these, NiCo2O4 (NCO) is a semiconductor material with anti-spinel structure and antibacterial properties. Herein, porous rod-like NCO was synthesized for use as antibacterial material against E. coli. The antibacterial properties and bactericidal mechanism under light and dark conditions revealed NCO with large specific surface area (51.707 m2/g), positive Zeta potential (17.3 eV), and more surface oxygen species. The bactericidal rate of 0.3 mg/mL NCO against E. coli under light and dark conditions reached 98.0% and 94.0%, respectively. The antibacterial mechanism of NCO under dark conditions illustrated the involvement of reactive metal Lewis acid active sites on its surface toward bacteria to produce lipid peroxidation, thereby inactivating bacteria. Under visible light irradiation, the main antibacterial ability was caused by the joint action of metal Lewis acid active site and reactive oxygen species. Overall, cyclic changes of valence states of metal elements and surface oxygen species in materials can be used for bacterial oxidative damage, relevant for bacterial disinfection.