Asymmetric Janus Patch Integrating Antifouling and Wet-Adhesive Functions for Infected Wound Repair

The wet, dynamic, and bacteria-contaminated microenvironment of infected wounds creates conflicting demands for stable wound-facing adhesion and outward antifouling protection. To address these demands, we developed an asymmetric Janus hydrogel-film patch (JP-TA/Fe) with a coordination-stabilized bilayer interface. The patch consisted of a dense nonadhesive layer containing silk fibroin/tannic acid (SF/TA) and an adhesive hydrogel layer containing polyacrylic acid/recombinant collagen/tannic acid (PAA/rhCol/TA). TA-Fe3+ chelation was introduced at the bilayer interface through a facile process to strengthen interlayer bonding and maintain bilayer structural integrity during hydration and mechanical deformation. The outward-facing SF/TA layer provided mechanical support and an antifouling barrier, whereas the wound-facing hydrogel layer exhibited favorable fluid-uptake capacity and maintained stable tissue adhesion. Benefiting from this asymmetric design, the patch exhibited robust wet-tissue adhesion, pH-responsive TA release, asymmetric antifouling and adhesive properties, antibacterial activity, biofilm-disrupting performance, and efficient reactive oxygen species (ROS)-scavenging capacity. In a rat full-thickness skin incision model and a Staphylococcus aureus-infected full-thickness skin defect model, JP-TA/Fe promoted stable wound closure, reduced bacterial burden, and accelerated collagen remodeling and epidermal regeneration. This study presents a structurally stable Janus wound patch with spatially differentiated functions, providing a multifunctional material platform for infected wound repair.