A NIR‐Responsive Deep Penetration Phototherapy Strategy for Treating Infected Skin Defect via Antibacterial Effect and Inflammation Elimination

The increasing severity of antibiotic resistance and the delayed healing of infected wounds have triggered an arduous challenge that threatens human health. Instantly, quiet a few novel, efficient, and safe antibacterial strategies are urgently needed to be explored. In this study, a NIR-activated antibacterial nanocomposite (RB/UCNPs@BP) integrating rose bengal-sensitized upconversion nanoparticles (RB/UCNPs) and black phosphorus (BP) is developed for promoting infection wound healing. The photodynamic therapy (PDT) and photothermal therapy (PTT) are employed here for synergistic antibacterial action, while UCNPs further improve the penetration depth of irradiation and treatment efficiency. More importantly, the typical biodegradability of BP confers reduced resistance on nanocomposites through residual-free antimicrobial methods. The results show that RB/UCNPs@BP significantly inhibits the growth of both Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus) via enhanced PDT and PTT. Besides, the infected wounds achieve better healing by accelerating fibroblast proliferation and migration, reducing inflammatory cell infiltration, and promoting neuronal regeneration and angiogenesis. This study provides a promising and anti-resistant strategy with light-triggered antibacterial and anti-inflammatory activities that can promote the regeneration of infected skin tissue.