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

Abstract

Facing severe bacterial threats and the growing challenge of antibiotic resistance, the development of effective antibacterial materials remains urgent. Herein, we present a novel strategy for fabricating carbon dots (CDs) with broad-spectrum antimicrobial activity and excellent biocompatibility. The CDs were synthesized under mild conditions using cetylpyridinium chloride (CPC) as a precursor by simply controlling the reaction time. The resulting CDs exhibit significantly enhanced antibacterial activity compared with CPC, along with lower cytotoxicity and minimal hemolysis. Notably, CD₂ (obtained after 2 h reaction) has a minimum inhibitory concentration (MIC) of 32 µg mL⁻¹ and 16 µg mL⁻¹ 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 their 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 the biomedical field.