Liquid exfoliation of V8C7 nanodots as peroxidase-like nanozymes for photothermal-catalytic synergistic antibacterial treatment.

Nanozymes are effective antibiotics that use reactive oxygen species (ROS) produced by Fenton/Fenton-like reactions to kill bacteria. However, its activity is still not satisfactory and requires large amounts of hydrogen peroxide (H2O2) with side effects on normal tissues. Herein, ultrasmall V8C7 nanodots (NDs) are successfully constructed by the liquid-phase exfoliation method for photothermal-catalytic synergistic antibacterial treatment. The prepared V8C7 NDs are horseradish peroxidase (HRP)-like nanozymes that can efficiently catalyze H2O2 to produce a large amount of ROS. Unlike traditional HRP-like nanozymes, V8C7 NDs can have a good catalytic effect under slightly acidic conditions (pH=5.5). Moreover, V8C7 NDs have good near-infrared (NIR) absorption and high photothermal conversion efficiency (PTCE, 50.39%), which can be used for photothermal treatment (PTT) of bacteria. In addition, the mild photothermal effect can further enhance the HRP-like catalytic activity of V8C7 NDs, thereby further enhancing the antibacterial performance of V8C7 NDs. In vitro results show that V8C7 NDs can effectively eradicate Escherichia coli (E. coli, gram-negative) and methicillin-resistant Staphylococcus aureus (MRSA, gram-positive) under laser irradiation and the presence of H2O2, possessing spectral antibacterial properties. More importantly, V8C7 NDs display satisfactory therapeutic effects on wounds infected by MRSA in vivo, and their toxicity is negligible, suggesting that they may have great potential for application as powerful and safe antibacterial agents. This work presents a practical antibacterial strategy by combining PTT and catalytic therapy to achieve efficient treatment of bacteria-infected wounds. STATEMENT OF SIGNIFICANCE: (1) Ultrasmall V8C7 NDs were prepared by the liquid-phase exfoliation method. (2) V8C7 NDs showed good photothermal, catalytic properties. (3) V8C7 NDs achieved satisfactory photothermal-catalytic synergistic antibacterial treatment.