A structurally reassembled sunflower stem pith composite sponge for prehospital temporary emergency hemostasis

Uncontrolled bleeding is a major cause of life-threatening conditions in emergency situations. Due to their limited blood absorption and procoagulant capacity, current hemostatic materials often exhibit poor efficacy in treating uncontrolled bleeding. Although sunflower stem pith (SSP) has been proved to facilitate blood coagulation, its practical application is restricted by anisotropic fluid absorption and low mass transfer efficiency. In this study, a novel SSP composite hemostatic material was prepared by disrupting the anisotropic structure of SSP and reassembling it into an isotropic architecture within a chitosan network, which exhibited controlled fluid absorption, shape memory and procoagulant properties. Among all the samples, the SSP composite sponge containing 1% chitosan (SSP + 1% CS) showed the highest blood absorption capacity, with the blood absorption ratio reaching 2009.8% (w/w) and a blood absorption speed of 140.3 μg (cm³ s)^-1, and a shape recovery ratio exceeding 95% in blood within 12 s. In vitro coagulation tests verified that the SSP composite sponge reduced the clotting time by more than 39% compared to gauze. The SSP composite sponge significantly shortened the hemostatic time and reduced the blood loss in four animal bleeding models. In the rabbit femoral artery injury model, the hemostatic time of the SSP composite sponge was 71.8 s, which was 32% shorter than 105.6 s of the QuikClot® group; the blood loss of the SSP group was 2.1 g, representing a 55% reduction relative to the 4.68 g in the QuikClot® group. Cytotoxicity and hemocompatibility assays confirmed the excellent biocompatibility of the SSP composite sponges. Consequently, the SSP composite sponge has turned out to be a promising material for prehospital emergency hemostasis, which provides a model of high-value applications of SSP bioresources.