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

In the field of skin wound treatment, traditional methods are often limited by the dual challenges of effectively clearing bacterial infections and accelerating wound healing. To address these issues, this study developed an innovative bioactive hydrogel that combines photothermally responsive antimicrobial and immunomodulatory effects. The hydrogel utilized methacrylated gelatin and oxidized dextran, forming a stable network structure through radical and Schiff bonds, loaded with black phosphorus (BP) nanosheets and curcumin (Cur). Characterization of the hydrogel's physicochemical properties revealed not only its excellent swellability, biodegradability, mechanical strength, thermal stability, and antioxidative properties but also its ability to control the release of Cur through the photothermal effect. Under 808 nm NIR irradiation, the suitable photothermal effect was observed with BP nanosheets at a concentration of 250 μg/mL under a power density of 1.5 W/cm2, and the photothermal conversion efficiency (η) was 41.34%. In vitro experiments showed that the hydrogel exhibited a bactericidal rate of over 90% against E. coli, S. aureus, and P. aeruginosa and more than 80% antibiofilm formation activity. After coculturing with HUVEC cells for 24 and 48 h, cell viability remained above 80%. Cell migration assay confirmed the hydrogel's effectiveness in promoting cell migration (closure rate reached 97.4% within 24 h). In a rat model with infected wounds, it was shown that on day 14, wounds were nearly healed, with an antibacterial rate of over 85%, the expression levels of proinflammatory factors TNF-α and IFN-γ were reduced, the expression of anti-inflammatory factors IL-4 and TGF-β1 was increased, re-epithelialization was observed, and collagen was deposited, which facilitated the rapid healing of the wounds. The hydrogel in this study with photothermal and immunomodulatory capabilities offers an efficient strategy for treating infected wounds.