Study of polydopamine-modified β-chitin nanofiber hydrogels for full-thickness wound healing

Developing natural polymer-based hydrogel with excellent injectability, suitable mechanical properties, and the ability to facilitate full-thickness skin wound healing is highly desirable in clinical application. Herein injectable hydrogels made of polydopamine (PDA) modified β-chitin nanofibers (β-ChNFs) were successfully prepared and applied for irregular wound healing. Compared with β-ChNFs hydrogels which were too weak to be used, the surface coating of PDA helped concentrate the β-ChNFs, and hydrogels with much higher strength were obtained and could be conveniently applied to the wound. The incorporation of chitosan oligosaccharide (COS) remarkably increased the hydrogels’ bioactivity. Shown as the biocompatibility measurement, ChNFs-PDA-COS hydrogels significantly promoted the proliferation of L929 cells. Demonstrated by the in vivo study in a rat full-thickness skin defect model, ChNFs-PDA-COS hydrogels with 1 % of COS significantly reduced inflammatory cell infiltration, improved the maturation of granulation tissue and well-organized collagen deposition, and regenerated thick dermis and epidermis with some cutaneous appendages at 9th post-operative day. All these contributed to the acceleration of wound closure and a better healing outcome as compared to the control group, indicating that the COS-incorporated ChNFs-PDA hydrogels are promising wound dressing for full-thickness skin tissue repair.