Self-Assembled Hydrogels Developed from THPA-γ4-Phe-γ4-Phe-OH Loaded with Icariin Promote Chronic Diabetic Wound Healing in Mice.

Peptide hydrogels are extensively used in biomedical applications due to their excellent biocompatibility and distinctive benefits stemming from their amino acid-derived architectures and functionalities. The exploration of hydrogels developed from peptide conjugates and natural products as potential biomaterials for chronic diabetic wound healing remains limited. Herein, we synthesized and characterized γ-dipeptide conjugates with piperic acid (PA) and tetrahydropiperic acid (THPA) containing γ4-Phe residues, PA-γ4-Phe-γ4-Phe-OH (P1), and THPA-γ4-Phe-γ4-Phe-OH (P2). Our findings showed that conjugate P2 exhibits a distinct hydrogel morphology in DMSO and H2O (1:1), as characterized by IR spectroscopy, circular dichroism (CD), and scanning electron microscopy (SEM). The P2 hydrogel exhibited higher proteolytic stability and lower cytotoxicity. Furthermore, the 1.0% (w/v) Icariin-loaded P2 hydrogel exhibited an encapsulation efficiency of 81.1%, which increased slightly to 82.66% at 1.5% (w/v), indicating that 1.0% (w/v) is the optimal drug-loading concentration for the P2 hydrogel network. The cumulative Icariin release profile showed an initial burst release of 89.0% at 12 h, followed by a gradual increase to 92.9% at 24 h. This sustained release behavior is likely attributed to the dense nanofibrous network and strong intermolecular interactions within the P2 hydrogel. The Icariin-loaded P2 hydrogel was further evaluated for diabetic wound-healing activity in-vitro and in-vivo. In-vitro scratch assays demonstrated enhanced fibroblast migration and proliferation, while in-vivo studies in a diabetic mouse model showed accelerated wound healing efficacy. Notably, it regulated inflammatory signals by downregulating pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and upregulating the anti-inflammatory cytokine IL-10, thus promoting a shift to a regenerative microenvironment. Histological analysis further confirmed the improved tissue architecture, indicating efficient progression through the healing phases.