A shape-memory hydrogel with triggered contraction and sustained antibacterial release for acute infected wound...

The healing of acute infected wounds is severely hindered by impaired skin contraction and a dysregulated microenvironment characterized by persistent infection and oxidative stress. Herein, we report a smart shape-memory hydrogel (Ag@HSN-AGPS) that integrates two distinct functions to address these challenges: triggered mechanical contraction and sustained antibacterial/antioxidant delivery. The hydrogel matrix is composed of gelatin and polyvinyl alcohol crosslinked by Fe^3 + coordination, which locks the material in a temporary stretched shape. Sodium ascorbate is encapsulated in pH-responsive hydrogel beads embedded within the matrix. Upon exposure to the wound microenvironment (pH 7.4), ascorbate is released, reducing Fe³⁺ to Fe²⁺ and unlocking the coordination network. This triggers programmable shape recovery, generating a sustained contractile force that actively pulls wound edges together-a bioinspired approach mimicking embryonic wound closure. Hesperetin silver nanoparticles (Ag@HSN NPs) are loaded into an adhesive surface layer composed of dopamine and sodium alginate. These nanoparticles release Ag⁺ and hesperetin in a sustained, diffusion-controlled manner, providing continuous antibacterial and antioxidant capacity. The results of in vivo experiments confirmed that Ag@HSN-AGPS hydrogel could promote wound healing and tissue regeneration, indicating its great potential in the treatment of acute infected wounds.