Biocompatible carbon nitride quantum dots nanozymes with high nitrogen vacancies enhance peroxidase-like activity for broad-spectrum antibacterial

Nanozyme antibacterial agents with high enzyme-like catalytic activity and strong bacteria-binding ability have provided an alternative method to efficiently disinfect drug-resistance microorganism. Herein, the carbon nitride quantum dots (CNQDs) nanozymes with high nitrogen vacancies (NVs) were mass-productively prepared by a simple ultrasonic-crushing method assisted by propylene glycol. It was found that the NVs of CNQDs were stemmed from the selective breaking of surface N-(C)₂ sites, accounting for 6.2%. Experiments and density functional theory (DFT) simulations have demonstrated that the presence of NVs can alter the local electron distribution and extend the π-electron delocalization to enhance the peroxidase-like activity. Biocompatible CNQDs could enter inside microorganisms by diffusion and elevate the bacteria-binding ability, which enhanced the accurate and rapid attack of ·OH to the microorganisms. The sterilization rate of CNQDs against Gram-negative bacteria (E. coli), Gram-positive bacteria (S. aureus, B. subtilis), and fungi (R. solani) reaches more than 99%. Thus, this work showed great potential for engineered nanozymes for broad-spectrum antibacterial in biomedicine and environmental protection.