A heterogeneous hydrogel patch with mechanical activity and bioactivity for chronic diabetic wound healing

Chronic wounds are common complications for diabetic patients, characterized by difficult healing because of the persistent and excessive inflammatory response, susceptibility to infection, and a lack of effective contraction stress at the diabetic wound site. In this study, we develop a heterogeneous hydrogel patch through the in situ free radical polymerization of acrylamide (AM) in the presence of modified alginate (Alg-Cat) within a porous polyurethane foam (DDLPU-foam). The polyurethane foam containing demethylated dealkaline lignin-Fe³⁺ complex structures (DDL-Fe³⁺) with photothermal properties endows the patches with excellent near-infrared (NIR) light-responsive shape memory performance, allowing the pre-stretched patches to provide biaxial contraction for diabetic wounds under NIR light, while also providing broad-spectrum photothermal antibacterial properties. The Alg-Cat in the hydrogel phase contains disulfide-linked catechol, offering antioxidant activity and flexible tissue adhesion. In vivo tests demonstrate that the DDLPU/Alg-Cat patch effectively reduces the inflammation level of chronic wound and promote tissue reconstruction, accelerating wound healing through combined mechanical modulation function and antioxidant activity. This heterogeneous hydrogel patch possesses both mechanical modulation function and bioactivity, providing a novel and effective strategy for treating chronic diabetic wounds.