Self-expanding cellulose sponge with enhanced hemostatic ability by tannic acid/metal ion composite coating for highly effective hemostasis of difficult-to-control bleeding wounds

Refractory bleeding presents a critical, life-threatening challenge, and the goal of medical professionals and researchers has always been to achieve safe and effective hemostasis for bleeding wounds. In this study, we utilized the benefits of a self-expanding cellulose sponge to control incompressible bleeding, which is achieved this by creating a tannic acid/metal ion coating on the surface and within the pores of the sponge to improve its hemostatic effectiveness. The effects of various types and concentrations of metal ions (calcium, magnesium, iron, and zinc) on hemostatic efficiency and biosafety is systematically investigated. The results from bacteriostasis and in vitro coagulation experiments identified 0.3 wt% Fe³⁺ as the optimal metal ion coating. Scanning electron microscope energy spectrum analysis confirmed the uniform distribution of Fe³⁺ within the cellulose sponge. Furthermore, the in vivo and in vitro results demonstrated that the prepared tannic acid/Fe³⁺ coated composite hemostatic sponge exhibits excellent coagulation ability and biocompatibility. Both the bleeding time and theblood loss in two bleeding models are significantly reduced, showing promising potential for treating extensive surface bleeding and deep penetrating wounds. Furthermore, the straightforward preparation method for this composite hemostatic sponge facilitates additional research towards market application.