Mechanism and different roles of metal-N sites on ZIF-8 for efficient antibacterial.

Bacterial pollution poses a serious threat to human health, making it essential to design and utilize efficient non-antibiotic antibacterial materials. Here, ZIF-8 with different metal-N sites is successfully prepared by introducing divalent metals (Mg2+, Mn2+, Co2+ and Cu2+) directly into the ZIF-8 framework. ZIF-8 with Cu-Nx sites has the best antibacterial activity, with antibacterial rates of 99.8 % and 81.1 % against Escherichia coli and Staphylococcus aureus after 1 h at a concentration of 10 µg/mL, respectively. More importantly, an antibacterial rate of more than 86.7 % can be achieved against multidrug-resistant bacteria MRSA, much higher than Vancomycin. The results show that the introduction of copper could significantly improve the electron transfer, the generation of reactive oxygen species (ROS), the binding affinity with bacteria, and eventually achieve excellent antibacterial activity. DFT calculations show easier oxygen activation at the unsaturated Cu-Nx site. The revealed oxygen activation mechanism sheds light on understanding the high antibacterial activity of the active site of the nanoparticles. Cu-ZIF-8 offers significant advantages in the field of air disinfection.