Multifunctional pH-responsive HA-c-FZ1 hydrogel presents a promising therapeutic strategy for diabetic skin wounds

Abstract

Background Diabetic foot ulcers (DFUs) remain a major clinical challenge, driven by the convergent effects of microbial infection, chronic inflammation, oxidative stress, and inadequate neovascularization that collectively disrupt tissue repair. Although the integrin αvβ3 agonist peptide FZ1 exhibits promising pro-healing activity, limited delivery control and insufficient functional versatility have restricted its clinical translation. To overcome these constraints, a pH-responsive hyaluronic acid (HA)-based hydrogel, HA-c-FZ1, was developed to enable intelligent acidity-triggered peptide release while integrating antimicrobial activity, reactive oxygen species (ROS) scavenging, and inflammation control within a single wound dressing platform for diabetic wound repair. Methods First, photo-crosslinkable oxidized methacrylated HA (O-HAMA) was synthesized and covalently linked to FZ1 through a pH-labile Schiff base bond, yielding HA-c-FZ1 hydrogels at three concentrations (2%, 3%, and 4%). Hydrogel morphology, swelling behavior, mechanical properties, peptide-loading efficiency, pH-responsive release, antioxidant activity, antibacterial activity, biocompatibility, and anti-inflammatory effects were systematically evaluated in vitro. Therapeutic efficacy was then assessed in a diabetic mouse model with infected full-thickness skin wounds through wound closure analysis, histological staining, immunofluorescence detection of macrophage polarization markers (iNOS and ARG) and angiogenic markers (α-SMA and VEGF), and laser speckle imaging of blood perfusion. Transcriptomic profiling, RT-qPCR, and western blotting were performed to define the molecular mechanisms underlying HA-c-FZ1-mediated wound repair. Results HA-c-FZ1 formed a homogeneous porous hydrogel network with predictable swelling behavior, tunable mechanical performance, high FZ1 loading efficiency, and accelerated peptide release under acidic conditions. In vitro, HA-c-FZ1 promoted keratinocyte proliferation and migration, reduced ROS accumulation, and inhibited Staphylococcus aureus and Escherichia coli survival. In infected diabetic wounds, HA-c-FZ1 suppressed bacterial burden and accelerated wound closure, accompanied by enhanced re-epithelialization, collagen deposition, angiogenesis, and local blood perfusion. Mechanistic analyses indicated that HA-c-FZ1 attenuated NF-κB-associated inflammatory signaling, promoted M2 macrophage polarization, and activated FAK-AKT-dependent angiogenic responses. Conclusion HA-c-FZ1 functions as a pH-responsive hydrogel dressing that combines peptide delivery and antimicrobial, redox-regulatory, immunomodulatory, and pro-angiogenic functions. These findings position it as a therapy for chronic diabetic wound repair by simultaneously addressing infection, inflammation, oxidative stress, and vascular regeneration.