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

Diabetic foot ulcers 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, hyaluronic acid conjugated with FZ1 peptide (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.

Photo-crosslinkable oxidized methacrylated HA was synthesized and covalently linked to FZ1 through a pH-labile Schiff base bond, yielding HA-c-FZ1 hydrogel at three concentrations (2%, 3%, and 4%). HA-c-FZ1 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 (inducible nitric oxide synthase and arginase) and angiogenic markers (alpha-smooth muscle actin and vascular endothelial growth factor), 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.

HA-c-FZ1 hydrogel 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 hydrogel promoted keratinocyte proliferation and migration, reduced ROS accumulation, and inhibited Staphylococcus aureus and Escherichia coli survival. In infected diabetic wounds, HA-c-FZ1 hydrogel 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 hydrogel attenuated nuclear factor kappa B-associated inflammatory signaling, promoted M2 macrophage polarization, and activated focal adhesion kinase-protein kinase B-dependent angiogenic responses.

HA-c-FZ1 functions as a pH-responsive hydrogel dressing that combines peptide delivery with 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.