Photothermal self-healing hydrogel based on Bletilla striata polysaccharide/humic acid for promoting wound healing in diabetic infections.

The characteristics of diabetic wounds include persistent oxidative stress, chronic inflammation, and impaired tissue regeneration, making effective treatment challenging. A multifunctional self-healing hydrogel was developed by co-grafting Bletilla striata polysaccharide (BSP) with 3-aminophenylboronic acid and polyvinyl alcohol (PVA) via dynamic borate ester bonds. The resulting CBPP/PVA@HAs gel exhibits rapid self-healing properties, sprayability, tissue adhesiveness, and good biocompatibility. In vitro studies demonstrated that the gel showed efficient photothermal antibacterial activity against E. coli, S. aureus, and MRSA, effectively scavenged intracellular reactive oxygen species (ROS), and promoted the polarization of RAW264.7 macrophages toward the anti-inflammatory M2 phenotype. In vivo experiments further demonstrated that the hydrogel significantly accelerated diabetic wound healing, promoted collagen deposition, angiogenesis, and tissue regeneration. Mechanistically, the hydrogel activated the Nrf2/HO-1 antioxidant pathway, reduced the pro-inflammatory cytokines TNF-α and IL-1β, and increased anti-inflammatory cytokines (IL-10) and reparative factors (TGF-β). Consequently, the hydrogel improved the inflammatory microenvironment by alleviating oxidative stress. Overall, CBPP/PVA@HAs gel represents a promising therapeutic strategy for diabetic wounds by simultaneously regulating oxidative stress and inflammation.