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

A multifunctional self-healing hydrogel based on dynamic borate ester bonds was developed for diabetic infected wounds. • Humic acid endowed the hydrogel with near-infrared-triggered photothermal antibacterial and potent ROS-scavenging capabilities. • The hydrogel effectively modulated the immune microenvironment by promoting RAW264.7 polarization toward the pro-healing M2 phenotype. 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. Schematic diagram illustrating the mechanism of action of the hydrogel in repairing diabetic infected wounds. Download: Download high-res image (121KB) Download: Download full-size image