Boosting antibacterial activity of positively charged carbon dots: mechanism and application

Facing severe bacterial threats and the growing challenge of antibiotic resistance, the development of effective antibacterial materials remains an urgency. Herein, we present a novel strategy for fabricating carbon dots (CDs) with broad-spectrum antimicrobial activity and excellent biocompatibility. The CDs was synthesized under mild conditions using cetylpyridinium chloride (CPC) as a precursor by simply controlling the reaction time. The resulting CDs exhibits significantly enhanced antibacterial activity compared to CPC, along with lower cytotoxicity and minimal hemolysis. Notably, CD2 (obtained after 2h reaction) has a minimum inhibitory concentration (MIC) of 32 μg/mL and 16 μg/mL against gram-negative E. coli and gram-positive S. aureus, respectively. Mechanistic investigations revealed that the positive surface change, hydrophobic groups and ultra-small size of CD2 promote effective interaction with and penetration into bacterial cells, ultimately leading to its death. Moreover, CD2-coated medical gauze and fabric exhibited potent bactericidal performance, highlighting its potential for clinical applications. This work offers valuable insights for the development of high-performance antibacterial materials in biomedical fields.