Defect-rich RuO2/IrO2 heterojunction with dual enzyme-mimic activities for boosting biocatalytic disinfection

The increasing bacterial resistance caused by the abuse of antibiotics has become an urgent global healthcare challenge. Recent advances in nanozymes represent one feasible solution. However, efforts have mainly focused on mimicking natural enzymes for comparable biocatalytic activities, as preparing nanozymes with superior antibacterial properties remains challenging. In this study, inspired by the Fe catalytic site in horseradish peroxidase (HRP), we synthesized defect-rich ruthenium oxide/iridium oxide heterojunction nanosheets (RuO2/IrO2), using Ru, which possesses a similar electronic structure to Fe, as the catalytic site to enhance antibacterial properties. Benefiting from the typically high catalytic activity of Ru in various reactions and the unique Ir-mediated defect-rich heterostructure, RuO2/IrO2 exhibits dramatically enhanced biocatalytic activities in generating reactive oxygen species crucial for eradicating bacteria. In particular, RuO2/IrO2 exhibited both oxidase and peroxidase-mimicking activities with catalytic efficiency 103 to 104 times higher than that of HRP. It exhibited superior antibacterial properties as well as high biosafety, effectively eliminating H2O2 toxicity during in vivo anti-infection measures. Minimum inhibitory concentration (MIC) values of RuO2/IrO2 against Staphylococcus aureus and Escherichia coli were 31.25 and 15.62 μg mL−1, respectively. This study offers a promising potential design for antibacterial nanozymes.