Construction of ZnO/Cu2O composites for enhanced antibacterial activity and analysis of antibacterial mechanism

Composite antibacterial materials were prepared by loading ZnO with good stability and biocompatibility on Cu2O. Cu2+ was released slowly due to the loading of ZnO, so the ZnO-Cu2O composites achieved lasting antibacterial effect. The basic form of the resulting ZnO/Cu2O composites, chemical composition, and crystal structure analyses were carried out by scanning electron microscopy (SEM), electron diffraction spectroscopy, Brunauer–Emmett–Teller method, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and X-ray phosphorescence. The optical properties of ZnO/Cu2O composites were determined by UV–vis spectroscopy and photoluminescence spectroscopy. E. coli and S. aureus were used to detect the antibacterial properties of the ZnO/Cu2O composites. The antibacterial mechanism of ZnO/Cu2O composites was investigated through ion dissolution, reactive oxygen species (ROS), and mechanical damage experiments. The results show that the increase in specific surface area, slow release of Cu2+ and increase in ROS lead to better antibacterial activity of ZnO/Cu2O composites. The antibacterial mechanism of these ZnO/Cu2O composites involves ion release, active oxygen and mechanical damage. The internal damage of bacteria was further analyzed by lipid peroxidation, protein leakage, respiratory chain dehydrogenase activity and bacteria in vitro fluid ion to thoroughly understand the inactivation mechanism of bacteria by the composite antibacterial material.