Tannic acid-copper ion@black phosphorus doped cationic guar gum/polyvinyl alcohol nanocomposite hydrogel for burn wound healing with antioxidant and photothermal antibacterial activities

Burn wounds present unique challenges for dressings due to severe vascular damage, irregular wound shapes, and excessive reactive oxygen species (ROS). In this work, we designed a bio-based multifunctional hydrogel dressing possessing antioxidant, antibacterial, and angiogenic properties. The hydrogel matrix was functionalized by embedding black phosphorus nanosheets (BPNS) coated with a tannic acid-copper ion complex (BPNS@TA-Cu), thereby imparting unique pH-dependent dual functions to the resulting composite. Specifically, under acidic microenvironments, it demonstrates a synergistic combination of photothermal therapy (PTT) and peroxidase-like (POD) activity, conferring potent antibacterial efficacy. In contrast, under neutral conditions, the material effectively scavenges reactive oxygen species (ROS) and reactive nitrogen species (RNS), thereby exhibiting outstanding antioxidant properties. The hydrogel's rapid self-healing and shape adaptability arose from a dynamic cross-linked network formed via borate ester bonds among gelatin (Gel), polyvinyl alcohol (PVA), cationic guar gum (CG), BPNS@TA-Cu, and borax. This adaptability allowed the dressing to conform to and fill irregular burn wounds, ensuring close contact. The hydrogel promoted full-thickness burn defect wound healing by facilitating granulation tissue formation, epithelial regeneration, and collagen deposition. Collectively, these findings establish the GPC-BTC hydrogel as a viable and promising multifunctional dressing strategy to accelerate burn wound healing.