Photodynamic therapy (PDT) is widely recognized as an effective antimicrobial strategy that minimizes the risk of bacterial resistance. Exploiting the intrinsic properties of hydrogels to create a favorable microenvironment for wound healing, researchers integrated bismuth-based metal particles into a chitosan-polyvinyl alcohol gel matrix. Representative gel complexes after metal-gel networks (Bi-gel) and composites introduced by biomass-derived carbon (BC) immobilized by cross-linking are referred to as CP/BC@Bi. The incorporation of carbon created a dual-network that enhanced electron transfer at the Bi‑carbon heterojunction, reduced electron-hole recombination, and optimized photogenerated carrier separation and migration. In vitro experiments showed that the excessive reactive oxygen species (ROS) generated by CP/BC@Bi under visible light enhanced PDT-mediated antimicrobial efficacy, causing complete bacterial membrane disruption and biofilm inhibition. Additionally, the surface roughness and defects of CP/BC@Bi enhanced bacterial adhesion, promoting ROS-bacterial interactions and amplifying its antimicrobial effects. Notably, the inhibition rates for Escherichia coli and Staphylococcus aureus were found to be 96 % and 94 %, respectively. Biocompatibility was rigorously assessed through hemocompatibility, cytotoxicity, and post-healing tissue staining experiments, all of which confirmed the safety profile of the hydrogel. In vivo studies demonstrated that wounds treated with PDT-CP/BC@Bi exhibited significantly accelerated healing rates, substantial dermal tissue regeneration, and normalized levels of inflammatory markers. This work demonstrates the potential of the environmentally friendly, resistance-free photodynamic antimicrobial hydrogel dressing in wound healing while offering insights into optimizing Bi-based hydrogels.
