NIR-induced in situ production of hydrogen peroxide by C-Fe3O4-CuO2 nanozyme for photothermal eradication of bacteria

A disinfection cascade system is proposed in this research based on the C-Fe3O4-CuO2 nanozyme. CuO2 in situ generates Cu2+ and H2O2 spontaneously under the NIR irradiation (808 nm). Afterward, Cu2+ catalyzes H2O2 to produce ·OH through a Fenton-like reaction, and H2O2 activates the peroxidase-like activity of Fe3O4 nanoparticles. Under the cascade reactions, C-Fe3O4-CuO2 composite (100 μg/mL) effectively kills Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) for 100 % and efficiently eliminates the bacterial biofilms. After three cycles, the recyclable C-Fe3O4-CuO2 remains at more than 90 % killing activity towards bacteria under the NIR irradiation. The ·OH and 1O2 are identified as the main reactive species during the disinfection process.