A bioactive dextran-based hydrogel promote the healing of infected wounds via antibacterial and immunomodulatory

Bacterial infection will attack the wound and aggravate inflammation, which is the main reason for the difficulty in wound healing. Here, we reported a dextran-based hydrogel composed of methacrylated gelatin (GelMA) and oxidized dextran (oDex), which loaded with black phosphorus (BP) nanosheets and zinc oxide nanoparticles (ZnO NPs). The hydrogel exhibited synergistic antibacterial activity of photothermal and zinc ions with an irradiation of 808 nm NIR laser. Meanwhile, trace zinc released from the hydrogel reduced polarization of macrophages towards the M2 phenotype. A larger proportion of M2 macrophages secreted anti-inflammatory factors and cytokines to reduce inflammation and facilitate neovascularization. Under the combined treatment of photothermal stimulation and immune factors, more neovascularization and shorter inflammation appeared in infected full-thickness defect wounds of mouse, which greatly accelerated wounds closure. Therefore, the combined treatment of antibacterial activity and anti-inflammatory properties of hydrogel Gel/BP/ZnO + NIR is suggested to be a hopeful approach for chronic wounds.