Synthesis and fabrication of a keratin-conjugated insulin hydrogel for the enhancement of wound healing

Accelerating and regulating collagen formation during wound healing repair is key issues for skin regeneration. Insulin can promote the healing of damaged skin by stimulating cellular migration and angiogenesis. Here, human hair keratin-conjugated insulin was synthesized to enhance full-thickness skin regeneration based on the excellent wound healing and hemostatic effects of keratin and the collagen deposition regulation ability of insulin. The insulin-conjugated keratin (Ins-K) was synthesized through the EDC/NHS reaction, which can supply a sustained release of insulin. The Ins-K hydrogel displayed similar water absorption, porosity and rheology properties to those of the keratin hydrogel. However, the Ins-K hydrogel shows a stronger hemostatic ability than the keratin hydrogel group, with a stronger wound healing effect found for the Ins-K hydrogel in the early regeneration stage (first 2 weeks) than for the keratin hydrogel treatment, resulting in smoother skin tissues at an excision section realized by regulating transforming growth factor β1 (TGF-β1) and hydroxyproline (HYP) expression. The results demonstrate that keratin promotes hemostasis and wound healing after insulin conjugation, which highlights the potential of keratin-based materials in tissue regeneration applications.