Photothermal and Immunomodulatory Hydrogels Loaded\nwith Black Phosphorus Nanosheets and Curcumin for Wound Healing

In the field of skin wound treatment,\ntraditional methods are often\nlimited by the dual challenges of effectively clearing bacterial infections\nand accelerating wound healing. To address these issues, this study\ndeveloped an innovative bioactive hydrogel that combines photothermally\nresponsive antimicrobial and immunomodulatory effects. The hydrogel\nutilized methacrylated gelatin and oxidized dextran, forming a stable\nnetwork structure through radical and Schiff bonds, loaded with black\nphosphorus (BP) nanosheets and curcumin (Cur). Characterization of\nthe hydrogel’s physicochemical properties revealed not only\nits excellent swellability, biodegradability, mechanical strength,\nthermal stability, and antioxidative properties but also its ability\nto control the release of Cur through the photothermal effect. Under\n808 nm NIR irradiation, the suitable photothermal effect was observed\nwith BP nanosheets at a concentration of 250 μg/mL under a power\ndensity of 1.5 W/cm<sup>2</sup>, and the photothermal conversion efficiency\n(η) was 41.34%. In vitro experiments showed that the hydrogel\nexhibited a bactericidal rate of over 90% against E.\ncoli, S. aureus, and P. aeruginosa and more than 80% antibiofilm formation\nactivity. After coculturing with HUVEC cells for 24 and 48 h, cell\nviability remained above 80%. Cell migration assay confirmed the hydrogel’s\neffectiveness in promoting cell migration (closure rate reached 97.4%\nwithin 24 h). In a rat model with infected wounds, it was shown that\non day 14, wounds were nearly healed, with an antibacterial rate of\nover 85%, the expression levels of proinflammatory factors TNF-α\nand IFN-γ were reduced, the expression of anti-inflammatory\nfactors IL-4 and TGF-β1 was increased, re-epithelialization\nwas observed, and collagen was deposited, which facilitated the rapid\nhealing of the wounds. The hydrogel in this study with photothermal\nand immunomodulatory capabilities offers an efficient strategy for\ntreating infected wounds.