Layer-by-layer coating of carboxymethyl chitosan-gelatin-alginate on cotton gauze for hemostasis and wound healing

We developed a hemostatic material able to quickly stop wound bleeding by successively constructing carboxymethyl chitosan (CMC), gelatin, and alginate onto a cotton gauze surface through a simple layer-by-layer (LbL) process. Briefly, we grafted CMC onto the cotton fibers through an esterification reaction with the hydroxyl groups of the cellulose chains, and then built a gelatin layer on the CMC layer by the ionic reactions with CMC. Finally, we integrated alginate by the lamellar structure through the cross-linking reactions caused by the Ca2+ ions permeated from the gelatin layer. Characterization analyses demonstrated that the resulting composite dressing possessed high fluid absorption, excellent biocompatibility, and hemocompatibility. A better hemostatic performance was also revealed in animal tests compared with cotton gauze, and it showed a short hemostasis time and a small amount of blood loss in the mouse liver injury model and mouse-tail amputation model. Moreover, the composite dressing also exhibited a significant promotion effect of wound healing in a mouse defect wound model. This new composite dressing, which was prepared by natural raw materials, is a promising candidate for wound dressing and demonstrated great potential in medical applications.