Charge-Switchable Cu x O Nanozyme with Peroxidase and Near-Infrared Light Enhanced Photothermal Activity for Wound Antibacterial Application.

Bacterial infection is still a thorny problem threatening human health, and nanozymes offer a promising alternative strategy to combat the health threat posed by bacterial infection. However, the antibacterial efficacies of nanozymes are unsatisfactory because of low catalytic activity of nanozymes and their inability to trap bacteria. Herein, a multifunctional nanozyme, polydopamine (PDA)-modified copper oxide (Cu x O-PDA) is designed to overcome this challenge. Cu x O-PDA showed peroxidase-mimicking activity and the catalytic activity was enhanced upon near-infrared (NIR) irradiation. Cu x O-PDA was negatively charged under neutral or alkaline condition and showed no obvious peroxidase-mimicking activity. On the contrary, the surface charge of Cu x O-PDA can be switched to positive under acidic conditions, which can target negatively charged bacteria. More interestingly, well-dispersed Cu x O-PDA can aggregate rapidly under NIR irradiation, which trapped the bacteria and nanozymes together. It was found that shortening the distance between nanozyme and bacteria could improve the antibacterial effect. The obtained Cu x O-PDA can cause DNA degradation, lipid peroxidation, and biofilm eradication. Cu x O-PDA showed good antibacterial effect against two kinds of representative bacteria, Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The experiment in vivo further proved favorable antibacterial activity of Cu x O-PDA nanozyme.