关键词: 碳酸钙, 壳聚糖, 海藻酸钠, 止血海绵, 体外凝血, 液体吸收

Abstract: In daily life as well as in clinical surgery, the first problem that needs to be solved is how to quickly stop bleeding from wounds. Prolonged exposure of wounds to air can easily lead to infections and loss of bodily fluids, which can impact wound healing and, in severe cases, even cause complications. This can impact wound healing and, in severe cases, even lead to complications. Traditional dressings are still widely used on skin injuries, primarily due to their affordability, simplicity in preparation, and ease of application. However, their role in wound healing is limited by their simple physical coverage, tendency to adhere to wounds and limited capacity to absorb tissue fluid, which restricts their effectiveness in wound healing. Natural polysaccharides are highly advantageous in the direction of preparing new sponge dressings due to their excellent biocompatibility, degradability, widespread availability, and affordability. Sponge dressings made from polysaccharides not only retain the sponge's excellent breathability and fluid absorption capabilities but also possess the inherent advantages of polysaccharides.
Calcium carbonate (CaCO3) is an inorganic material widely found in natural substances such as limestone and coral, which is inexpensive, readily available, safe and non-toxic, and therefore has garnered significant attention in the biomedical industry. To improve the sponge formed by the exogenous gel method of freeze-drying traditional calcium alginate sponges, it is necessary to address issues such as hard texture, lengthy process, and uneven cross-linking. One way to achieve this is by re-crosslinking the sponge through immersion in calcium chloride solution. The thesis uses sodium alginate (SA) and chitosan (CS) as the base materials, CaCO3 as the source of Ca2+ for ionic cross-linking, and regulates the pH value of the solvent to control the cross-linking speed to simultaneously trigger ionic cross-linking and electrostatic interactions, and employs internal gelation to stabilize the sponge's cross-linked structure, so that the sponge dressings which are soft and skin-friendly and able to stop hemostatic quickly are prepared. The main research is as follows: CS and SA were dissolved in pH=4.5 acetic acid-sodium acetate solution, and then CaCO3 suspension was uniformly dispersed in the mixture, which was left to cross-link for 24 h and then frozen at -20 ℃, and the sponge samples of uniform texture were produced by vacuum freeze-drying. This study explored the formation mechanism, morphological structure, physicochemical properties, blood safety, and hemostatic performance of the sponge. The sponge samples were made by vacuum freeze-drying. The test results showed that the sponge had better performance when the CaCO3 mass fraction was 0.4%, with a liquid absorption rate of (1,234±49.36)%, a coagulation index (BCI) of (13.924±0.963)%, an in vitro degradation rate of (76.708±2.302)%, and a haemolysis rate of less than 5% in all cases. The sponge exhibits excellent liquid absorption capacity, rapid hemostasis, safety, non-toxicity, and in vitro degradability, making it a potential candidate for biological hemostatic materials.
Due to the basic nature of the sponge material, the novel hemostatic sponge exhibits a limitation in terms of poor mechanical properties. In future research, it is anticipated that combining the sponge with traditional dressings could enhance hemostasis and wound healing effects while simultaneously improving mechanical properties. And the intricate porous structure of the sponge dressing also makes it has a great potential for drug loading applications.

Key words: calcium carbonate, chitosan, sodium alginate, hemostatic sponge, extracorporeal coagulation, liquid absorption