Unusual Antibacterial Property and Selectivity Enabled by Tuning Nanozyme Activities of L-Arginine Derived Carbon Dots.

Functional integration of antimicrobial activity and cell proliferation promotion at low concentrations is important for the clinical application of carbon dots (CDs). In this study, the precursor, L-arginine, and dopant, copper salt, are used to prepare copper-doped CDs (Cu-CDs). Owing to their excellent synergistic enzyme-like activities, Cu-CDs can rapidly increase reactive oxygen species (ROS) to lethal levels, preferentially in bacteria, and exhibit potent antibacterial ability, which can mainly be attributed to the membrane disruption effect. Concurrently, the cell proliferation-promoting activity of arginine-derived CDs is inherited. The Cu-CDs achieve perfect integration of dual functions at low concentrations, especially advantageous for applications. With as little as 100 µg mL^-1 of Cu-CDs, the infected wound heals obviously faster than 2 mg mL^-1 of antibiotic, although the traditional antibiotic group shows slightly better antibacterial efficiency, suggesting its effect in simultaneously scavenging bacteria and promoting tissue repair effect in vivo. The super selective mechanism probably originates from the endocytosis of Cu-CDs by mammalian cells, while superoxide dismutase down-regulates ROS levels in cells to act as a mitotic signaling agent for promoting cell growth. This strategy provides an efficient, convenient, and safe solution to combat bacterial infections, and suggests a novel approach for modifying antimicrobial biomaterials.