The exploitation of local electric field generated by oxygen vacancies on BiOIO3 nano-antibacterial agents for enhanced photocatalytic sterilisation

Methicillin-resistant Staphylococcus aureus (MRSA) is a typical Gram-positive foodborne pathogen, and its infection has been reported since its discovery. Photocatalysis has emerged as a safe and efficient new sterilization method in clinical and food sectors. In this study, we developed an oxygen vacancy-rich BiOIO₃ nano-antibacterial agent using a hydrothermal method, which was successfully synthesized and confirmed through various characterization techniques. Notably, the BiOIO₃ nano-antibacterial agent exhibits almost complete inactivation of 10⁷ CFU/mL MRSA within 2 h under visible light irradiation. Furthermore, with increasing exposure duration to irradiation, gradual shrinkage and disintegration of the MRSA cell membrane were observed along with inhibition of the intracellular enzyme activity. Haemolysis tests were performed to prove the biological safety of the agent. Mechanistic investigations revealed that surface oxygen vacancies of BiOIO₃ facilitated adsorption binding of water and oxygen within a local electric field promoting reactive oxygen species (ROS) generation. This leads to the rapid accumulation of ROS, which attacks the cell membrane causing significant damage, disrupting normal physiological metabolism of the bacteria, and ultimately killing MRSA. The present study is expected to provide a favourable solution for developing novel efficient and green nano-antibacterial agents through surface modifications.