Riboflavin-loaded Bletilla striata polysaccharide photodynamic hydrogel with synergistic antibacterial and anti-inflammatory effects for accelerating infected diabetic wound healing.

Bacterial infection represents a critical barrier to the healing of chronic diabetic wounds. Herein, a riboflavin-loaded Bletilla striata polysaccharide (BSP) hydrogel， namely CCBG-50R, was fabricated via dual dynamic crosslinking of hydrogen bonds and imine linkages. Hydrogel integrates the photodynamic bactericidal activity of riboflavin and the inherent anti-inflammatory of BSP to synergistically promote the repair of bacteria-infected diabetic wounds. Specifically, CCBG-50R hydrogel displayed a well-developed porous structure, outstanding water absorption capability with a swelling ratio of 1603 ± 25%, and excellent biocompatibility. Upon visible light irradiation for 7 min, CCBG-50R exhibited superior antibacterial activity, achieving more than 5-log reduction (99.999% inactivation) against both E. coli and S. aureus in vitro by generating reactive oxygen species (ROS: ·OH, ·O2-, 1O2). Mechanistic studies demonstrated that the CCBG-50R hydrogel exerted a synergistic effect between BSP mediated anti-inflammation and riboflavin mediated photodynamic sterilization. The accelerated wound healing can be attributed to the combined functions of efficient antibacterial disinfection, anti-inflammation, macrophage polarization regulation, tissue regeneration, and angiogenesis. This study provides a promising strategy for designing safe and effective polysaccharide-based photodynamic dressings toward infected diabetic wound management.