Enhanced photocatalytic and antimicrobial activities of carbon-dots nanozymes modulated with P-doping

Bacterial contamination poses a serious and global threats to public health. Due to broad-band antimicrobial capacity and unspecific tissue interaction, antibacterial nanomaterials offer promising alternative and green strategies to resist bacterial contamination. Herein, an enhanced metal-free carbon-dots nanozymes, i.e., m-aminophenol based phosphoric acid doping carbon dots (P-CDs), with excellent photoresponse enzyme-like properties are designed through a simple one-pot hydrothermal method for highly effective antimicrobial. Developed P-CDs exhibited superior photoresponse oxidase-like activity, which may attribute to the higher crystallinity conferred by P-doping. Interestingly, the generation of superoxide radicals (O2•−) under photocatalytic for such P-CDs exhibited excellent antimicrobical effects with a high maximum reaction rate (33.3 × 10-8 M/s). Notably, P-CDs effectively inhibited the growth of both Gram-positive and Gram-negative bacteria under a 1 W white LED irradiation, especially against Gram-positive Staphylococcus aureus (S. aureus). Plate counting experiments confirmed that 75 μg/mL P-CDs could kill 98 % of E. coli when illuminated for 60 min, however, 50 μg/mL P-CDs could inhibit 100 % of S. aureus for the same illumination time. Surely, our metal-free carbon dots nanozyme provides a strong and viable alternative for the management of bacterial contamination in food security and environmental preservation, as well as a theoretical basis for P-doping to promote photocatalytic activities of carbon-dots.