Tannic acid-crosslinked gelatin composite microspheres adsorbed with CQAS or Ca2+ for rapid hemostasis

In the case of massive blood loss due to natural disasters and wars, timely and rapid hemostasis is of great significance to improve the survival rate of injured people. Nevertheless, uncontrolled, noncompressible, and irregular bleeding wounds remain a giant challenge for rapid hemostasis. In this study, the tannic acid-crosslinked gelatin was first obtained by Michael addition reaction, and then the tannic acid-crosslinked gelatin composite microspheres (TGMs) were prepared by the emulsion cross-linking method. TGMs could significantly improve the water absorption and hemostatic performance compared with single component gelatin microspheres (GMs). Increasing the water absorption ratio and introducing blood coagulation factors into composite materials are simple and effective strategies to enhance the hemostatic properties. Therefore, chitosan quaternary ammonium salt (CQAS) and Ca 2+ were electrostatic adsorbed to obtain two kinds of functional TGMs, which were respectively CQAS-absorbed TGMs (T 2 GMs-CQAS) and calcium ion-absorbed TGMs (T 2 GMs-Ca 2+ ). Notably, T 2 GMs-CQAS, and T 2 GMs-Ca 2+ could absorb water rapidly within 3 seconds, in addition, especially the water absorption ratio of T 2 GMs-CQAS could reach 2.95 times compared with GMs. Benefited from rapid water absorption, coagulation pathway activation, and red blood cells aggregation of T 2 GMs-CQAS and T 2 GMs-Ca 2+ , resulting in rapid blood coagulation in vitro . In addition, CQAS and Ca 2+ provided strong and intrinsic antibacterial activity due to positive charge. Moreover, in the tail amputation and liver hemostatic models, T 2 GMs-CQAS and T 2 GMs-Ca 2+ demonstrated superior hemostatic effects compared to commercial Yunnan Baiyao®. In conclusion, T 2 GMs-CQAS and T 2 GMs-Ca 2+ have potential applications as hemostatic dressings in uncontrolled, noncompressible, and irregular bleeding wounds.