CuS Hybrid Hydrogel for Near-Infrared-Enhanced Infected Wound Healing: A Gelatin-Assisted Synthesis and Direct Incorporation Strategy

Developing antibacterial hydrogels, with good mechanical strength and self-healing ability to resist bacterial invasion and accelerate skin regeneration, is critical for infected full-thickness skin wound treatment. Herein, we report a gelatin-assisted synthesis and direct incorporation strategy to construct a CuS hybrid hydrogel for infected wound healing applications. CuS nanodots (NDs) were synthesized directly inside a gelatin host matrix (Gel-CuS), and these tightly confined and evenly distributed CuS NDs displayed superb dispersibility and stability against oxidation. Gel-CuS was then used to crosslink with oxidized dextran (ODex) to form a Gel-CuS-8/ODex hydrogel (8 stands for the concentration of CuS, in mM) via a facile Schiff-base reaction, which exhibited improved mechanical properties, excellent adhesion and self-healing ability, suitable swelling and degradation behavior, and good biocompatibility. The Gel-CuS-8/ODex hydrogel can act as an efficient antibacterial agent due to its photothermal and photodynamic properties under a 1064 nm laser irradiation. Furthermore, in animal experiments, when being applied as wound dressing, the Gel-CuS-8/ODex hydrogel significantly promoted infected full-thickness cutaneous wound healing through improved epidermis and granulation tissue formation and accelerated generation of new blood vessels, hair follicles, and collagen deposition after proper near-infrared irradiation treatment. This work provides a promising strategy to synthesize functional inorganic nanomaterials tightly and evenly embedded inside modified natural hydrogel networks for wound healing applications.