Green-Synthesized Multifunctional Carbon Dots from a Natural Nucleoside for Synergistic Antibacterial and Anti-Biofilm Therapies

The pursuit of sustainable antimicrobial strategies to combat biofilm infections has become imperative in addressing the global crisis of antibiotic resistance. Here, a green-chemistry paradigm is reported for fabricating multicolor-emissive carbon dots (A-CDs) through a solvent-free, single-step solvothermal process using adenosine. Under dual-light irradiation, A-CDs displayed enhanced antimicrobial activity against both bacteria and fungi through a triple-modal mechanism. RNA sequencing reveals that A-CDs combined with dual light irradiation disrupt bacterial metabolism, antioxidant systems, and cell wall integrity, effectively inhibiting bacterial proliferation and pathogenicity. A-CDs significantly inhibit biofilm formation and eliminate mature biofilms by destroying key components of extracellular polymeric substances and downregulating the key biofilm markers under laser light exposure. Its antibiofilm efficacy is further validated in a S. aureus biofilm-infected mouse model. Additionally, A-CDs exhibit high biocompatibility and minimal potential for resistance development over 25 days, making them a promising sustainable alternative to conventional antibiotics. These findings suggest that A-CDs can serve as an environmentally friendly, antibiotic-free solution for treating biofilm-related infections, offering broad clinical applications.