Sunlight PDT leveraging NIR-II nanospray: painless, hemostatic, anti-inflammatory therapy towards diabetic wound infections

Photodynamic therapy (PDT), which relies on the activation of photosensitizers by specific wavelengths of light to generate reactive oxygen species (ROS) for targeted pathogen or diseased tissue eradication, offers substantial promise for clinical wound management. However, its application in diabetic wound management remains constrained by suboptimal therapeutic efficacy, recurrent infections, treatment-associated pain, scar formation, and dependence on costly specialized equipment. Here, we present a sunlight-activated nanospray formulation comprising chitosan oligosaccharide-coated nanoparticles (SPS), engineered for the rapid and effective management of diabetic wounds in outdoor and resource-limited settings. SPS enables efficient ROS generation under ambient natural light, thereby reducing treatment-associated discomfort while maintaining effective photodynamic antimicrobial action. Additionally, the chitosan oligosaccharide coating confers intrinsic hemostatic, antibacterial, and antioxidative properties that synergistically accelerate wound closure and reduce the risk of scarring. The topical spray delivery circumvents systemic phototoxicity, improving patient compliance and broadening the accessibility of PDT. This strategy effectively overcomes the inherent limitations of conventional PDT by leveraging ambient light for activation and providing a cost-effective, non-invasive, and patient-friendly platform for diabetic wound care, thereby expanding the clinical utility of photodynamic interventions for managing chronic and complex wounds.