Bacterial infections pose a significant threat to human health. Clinically, the treatment of bacterial infections often relies on antibiotics. However, the emergence of “multi-drug resistant bacteria” due to antibiotic misuse has been a persistent challenge for the medical community, even leading humanity to a near “antibiotic-free” predicament. Metal-based nanozymes, with their high antibacterial activity and low resistance, have emerged as effective alternative strategies for treating bacterial infection wounds. However, single catalytic activity and limited antibacterial effects restrict its further development. In this study, a CuO/ZnO composite nanosphere was successfully prepared and used as nanozyme for the eradication of antibiotic-resistant bacteria. The CuO/ZnO composite nanosphere was characterized using transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen adsorption instruments, confirming its successful synthesis. The catalytic activity of the material was evaluated using two reactive oxygen probes, 3,3',5,5'-tetramethylbenzidine (TMB) and o-phenylenediamine (OPDA), revealing that the CuO/ZnO composite nanospheres possess both oxidase-like (OXD-like) and peroxidase-like (POD-like) activities. The catalytic activity of the composite nanospheres is significantly higher than that of individual CuO and ZnO nanospheres, validating the rationality of our synthesis strategy. The antibacterial performance of CuO/ZnO composite nanospheres at different concentrations was tested using the viable cell count method. The results indicated that the CuO/ZnO composite nanospheres at a concentration of 50 μg/mL, in the presence of H₂O₂, could generate reactive oxygen species through their multi-enzyme activity, effectively killing Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA), achieving a 100% inhibition rate. Subsequent studies on the antibacterial mechanism revealed that the high-efficiency bactericidal effect of CuO/ZnO composite nanospheres is primarily attributed to their disruption of bacterial cell membranes and leakage of intracellular proteins. Additionally, CCK-8 assays confirmed the good biocompatibility of CuO/ZnO composite nanosphere, with cell viability remaining above 80% even at a concentration of 100 μg/mL. In summary, this study provides new research perspectives for the application of metal-based nanozymes in the treatment of drug-resistant bacterial infections.

Key words: composite nanosphere, multi-enzyme activity, bacterial infection, reactive oxygen species, antibacterial mechanism