Bioinspired Asymmetric Double-Layer Dressings for Stepwise Treatment of Hemorrhagic Wounds

Although various dressings have been developed for wound healing, ideal dressings are still lacking to meet the requirements of coordinated hemostasis and angiogenesis for the management of hemorrhagic wounds. Herein, inspired by the gradient structure of natural skin, we propose a novel asymmetric double-layer dressing (BSP-PNS@CMCS) with spatiotemporally controllable functions of hemostasis and angiogenesis for the stepwise treatment of hemorrhagic wounds. The BSP-PNS@CMCS dressings are designed with an inner layer of Bletilla striata polysaccharide (BSP) sponges for initial hemostasis and an outer dense layer of carboxymethyl chitosan (CMCS) hydrogels loaded with panax notoginseng saponines (PNS) for angiogenesis during subsequent tissue reconstruction. Through in vivo experiments, we have demonstrated that the BSP-PNS@CMCS dressings could not only significantly reduce bleeding in rat liver-puncture hemorrhage wounds but also accelerate wound closure by suppressing the inflammatory response, promoting angiogenesis and collagen deposition in infected skin wounds of rats. In vitro and in vivo results indicate that such asymmetric double-layer BSP-PNS@CMCS dressing could be a prospective candidate for the stepwise treatment of hemorrhagic wounds, which also provides an effective strategy for other tissue repair applications.