Mussel-inspired adhesive bilayer hydrogels for bacteria-infected wound healing via NIR-enhanced nanozyme therapy

Preventing bacterial infection in situ and accelerating skin generation simultaneously are essentially important for wound healing. Herein, a mussel-inspired Ag nanozyme-based bilayer hydrogel is constructed to address the above concerns. The bilayer hydrogel is composed of a layer with large pores absorbing the wound exudate and allowing oxygen exchange and a layer with small pores keeping the wound moist and preventing bacterial invasion. Benefitting from the polydopamine (PDA) coating-reduced Ag nanoparticles (AgNPs), the hydrogel exhibits high near infrared (NIR) absorption at 808 nm to generate hyperthermia and NIR-enhanced peroxidase (POD-like) activity to produce hydroxyl radicals (•OH), which endows the hydrogel with excellent antibacterial properties when combined with the released Ag⁺. In addition, the hydrogel presents adhesiveness due to the catechol group on a PDA molecule. The in vivo test results demonstrate that the bilayer hydrogel can accelerate infected skin generation by facilitating collagen deposition, decreasing tumor necrosis factor-α secretion, and promoting vascular endothelial growth factor expression.