Silver crosslinked injectable bFGF-eluting supramolecular hydrogels speed up infected wound healing

Topical wound dressings with various silver compositions that exhibit effective bacterial inhibition properties are often used to treat infected wounds. However, a silver dressing with no bioactive functionality will typically delay subsequent wound repair processes. Therefore, development of a simple wound dressing containing silver and loaded with a bioactive drug is a very attractive solution. Herein, we developed a silver crosslinked injectable chitosan–silver hydrogel as a silver immobilization matrix, loaded with basic fibroblast growth factor (bFGF) as its cargo (namely, bFGF@CS–Ag) for treatment of both acute and infected wounds. The in vivo results showed that bFGF@CS–Ag significantly enhanced infectious wound regeneration compared to that of acute wounds. Further investigation demonstrated that the improved wound repair by bFGF@CS–Ag was ascribed to the effectiveness of bacterial inhibition, the promotion of granulation formation, collagen deposition, neovascularization and re-epithelization, and to the reduction of the inflammatory response through promotion of M2 macrophage polarization. These results proved that the immobilization of silver in the hydrogel not only reduced the side effects of silver on the bioactivity of bFGF but also allowed elution of bFGF in a controlled release manner. Thus, this novel system has promising therapeutic potential for topical treatment of wounds.