Light triggered programmable states of carbon dot liposomes accelerate chronic wound healing via photocatalytic cascade reaction

Bacterial infection in chronic wounds causes severe morbidity and mortality by prolonging the inflammation and proliferation phase during the healing process. Reported carbon nanomaterials can exert anti-microbial action; however, uncontrolled therapeutic response, cytotoxicity, and high dosage requirement have limited their potential. Toward the end, we have developed programmable carbon dot liposomes (CD_somes) from triolein through simple pyrolysis. CD_somes can achieve “on” and “off” states upon ultraviolet (UV; 385 nm) and green (532 nm) light irradiation, respectively. The “on” state CD_somes participate in a thermodynamically favorable photocatalytic reaction to produce hydrogen peroxide (H₂O₂), which acts as a substrate for the “off” state CD_somes (⋅CD_somes^– or ⋅CD_somes⁺; metastable radical state) to generate hydroxyl radicals (⋅OH) via peroxidase-mimicking activity. The cascade reaction was utilized against bacteria, including multidrug-resistant bacteria. The practicality of CD_somes was demonstrated by treating the methicillin-resistant S. aureus infected wounds, CD_somes were pre-activated with UV light irradiation to avoid direct harmful exposure to tissues followed by in situ green light irradiation. This encouraged rapid healing by boosting the inflammatory immune responses owing to the intrinsic properties of self-preserved oleic acid. Light-triggered CD_somes with substantial biocompatibility holds great potential as an intelligent anti-microbial modality, particularly for chronic wound healing.