Hollow Bismuth Nanoparticle-Loaded Gelatin Hydrogel Regulates M2 Polarization of Macrophages to Promote Infected Wound Healing.

Open wounds face severe bacterial infection, which affects the quality of healing. Photothermal antimicrobial therapy has received increasing attention as a broad-spectrum antimicrobial treatment that can avoid drug resistance. A variety of metallic materials have been used in the development of photothermal agents. However, there are few studies on bismuth as a photothermal agent and its use in tissue repair, so there is still a lack of clear understanding of its biomedical function. Here, a hollow bismuth nanosphere prepared from bismuth metal was developed for drug loading and photothermal antibacterial effect. The photothermal conversion efficiency of the hollow bismuth spheres reached 16.1%, and the bismuth-loaded gelatin-oxidized dextran (ODex)-based hydrogel achieves good antibacterial effects both in vivo and in vitro. The bismuth-loaded hydrogel can also promote the angiogenesis of human umbilical vein endothelial cells (HUVECs) and improve the proliferation of human keratinocytes cells (HaCaT) and the quality of wound healing. This discovery provides a new idea for the application of metal bismuth in the field of tissue repair and regeneration.