Carbon-Dots-Mediated\nImprovement of Antimicrobial\nActivity of Natural Products

The development of new microbicidal\ncompounds has become\na top\npriority due to the emergence and spread of drug-resistant pathogenic\nmicrobes. In this study, blue-emitting and positively charged carbon\ndots (CDs), called Du-CDs, were fabricated for the first time utilizing\nthe natural product extract of endophyte Diaporthe\nunshiuensis YSP3 as raw material through a one-step\nsolvothermal method, which possessed varied functional groups including\namino, carboxyl, hydroxyl, and sulfite groups. Interestingly, Du-CDs\nexhibited notably enhanced antimicrobial activities toward both bacteria\nand fungi as compared to the natural product extract of YSP3, with\nlow minimum inhibitory concentrations. Moreover, Du-CDs significantly\ninhibited the formation of biofilms. Du-CDs bound with the microbial\ncell surface via electronic interaction or hydrophobic interaction\nentered the microbial cells and were distributed fully inside the\ncells. Du-CDs caused cell membrane damage and/or cell division cycle\ninterruption, resulting in microbial cell death. Moreover, Du-CDs\nexhibited an improved antimicrobial effect and accelerated wound healing\nability with good biocompatibility in the mouse model. Overall, we\ndemonstrate that the formation of CDs from fungal natural products\npresents a promising and potential means to develop novel antimicrobial\nagents with great fluorescence, improved microbiocidal effect and\nwound healing capacity, and good biosafety for combating microbial\ninfections.