Tissue-like Soft Dual-Network Hydrogel Patch with Instant/Tunable Adhesion and Microenvironment Modulation for Infected Wound Healing

The disorganized microenvironment driven by bacterial infection is a key factor in delayed wound healing. Additionally, uncontrolled adhesion between dressings and wound sites inevitably occurs during long-term treatment, resulting in risks of wound exposure or secondary damage. Here, we designed a dual-network hydrogel patch (CHI(C)-F/N-A) based on an orthogonal cross-linking mechanism with instant/tunable adhesion properties and the function of synergistically modulating the microenvironment, which is designed to address these complex matters. The covalent network (N-A) consisting of N-isopropylacrylamide and acrylamide serves as the basic framework of the hydrogel, providing highly conformal and stable integration between the hydrogel and the tissue through abundant polar interactions, while the phase-transition property endows the hydrogel with the capability of weakening the adhesion strength via thermal stimulation. The noncovalent network (CHI(C)-F) formed by the coordination of caffeic acid-modified chitosan with Fe³⁺ integrates the outstanding antibacterial and antioxidant efficacy of alkaline polysaccharides and natural polyphenols, realizing synergistic modulation of the pathological microenvironment, thereby facilitating an overall wound healing. Notably, benefiting from the superior photothermal effect of polyphenol-metal coordination, the strategy of NIR-mediated regulation of the hydrogel adhesion strength was further extended. This hydrogel patch establishes a rational paradigm for wound dressings that couples satisfactory physical properties and bioactivities expected to surmount the difficulties of practical therapy for infected wounds.