Nanofibrous membrane/self-healing hydrogel double-layer nanocomposite dressings based on oxidized dextran and carboxymethyl chitosan loading ZIF-nanozyme for enhanced bacterial-infected diabetic wound healing.

Treatment of diabetic wounds at different stages remains a pressing challenge. By simulating the complex structure of natural skin, a multifunctional nanofibrous membrane/self-healing hydrogel double-layer nanocomposite dressing loading nanozyme was prepared to accelerate diabetic wound healing. The upper layer was prepared from a modified self-synthesized polyurethane (APU) nanofibrous membrane, and the bottom layer was made of an injectable self-healing hydrogel loaded with nanozyme based on oxidized dextran (ODex) and carboxymethyl chitosan (CMC). The APU nanofibrous membrane on the top can maintain a breathable and sterile environment, support the dressing, and promote cell proliferation and migration. Glucose oxidase (GOx) and l -arginine (L-Arg) at the bottom were co-doped with zinc-ZIF nanoparticles (GLZ) and acted as nanozymes for enzyme catalysis. Under the catalytic action of GOx, the high blood sugar in the wound was consumed, the pH of the microenvironment was reduced, and Zn was released, achieving an effective antibacterial effect. L-Arg was catalyzed by HO to generate NO in a lower pH environment, accelerating angiogenesis. Overall, the double-layer composite dressings loaded with ZIF-nanozyme exhibited comprehensive blood sugar regulation capabilities and antibacterial activity, which could promote angiogenesis and cell proliferation, and effectively treat chronic diabetic wounds.