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

Abstract

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 (CDsomes) from triolein through simple pyrolysis. CDsomes can achieve "on" and "off" states upon ultraviolet (UV; 385 nm) and green (532 nm) light irradiation, respectively. The "on" state CDsomes participate in a thermodynamically favorable photocatalytic reaction to produce hydrogen peroxide (H2O2), which acts as a substrate for the "off" state CDsomes (center dot CDsomes- or center dot CDsomes+; metastable radical state) to generate hydroxyl radicals (center dot OH) via peroxidase-mimicking activity. The cascade reaction was utilized against bacteria, including multidrug-resistant bacteria. The practicality of CDsomes 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 CDsomes with substantial biocompatibility holds great potential as an intelligent anti-microbial modality, particularly for chronic wound healing.