Preparation Of Chitosan/Lysine Coajugate And Study Of Its Effect On Blood Coagulation

In this work, a prospective hemostatic material was prepared via modifying chitosan with lysine. The main contents of the thesis include two parts as follows:1. Chitosan-lysine conjugate was prepared by modifying chitosan of different deacetylation degree with lysine using 1-ethyl-3(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide as coupling system, and the products was characterized by FTIR and Element Analysis. Coagulant potential of the prepared products and chitosan was reviewed thought their interaction with blood contents, such as erythrocytes, platelets and coagulation factors. Red blood cell/materials interaction was monitored through changes in optical density, and red blood cells'number was calculated before and after the experiment, and platelet/materials interaction was evaluated in the same way. Chitosan can apparently trigger the aggregation of erythrocytes, and the effect was dose-dependent and in line with its deacetylation degree as well and has little to do with lysine. The result indicated that platelet was activated as soon as it was exposed to chitosan membrane, accompanied with change in morphology. Platelets adhered strongly on the surface of chitosan-lysine membrane and were bound to each other to form aggregated mass. The data in fibrin clot-formation times showed that chitosan-lysine/platelet mixture can accelerate the process of fibrin gel formation. In coagulation activities experiment, activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time changed little in each group, and one can conclude that all the derivatives can't influence coagulation factors directly and their hemostatic potential may be independent of intrinsic coagulation cascade.2. In comparison with different chitosan derivatives and collagen in terms of coagulation activity, the results imply that there is possible specific interaction between platelet member and chitosan-lysine. Chitosan-lysine can aggregate platelets as good as collagen, and this is also the case in blood coagulation time.3. The cytotoxicity of chitosan–lysine conjugate were determined by 3-(4, 5-dimethylthiazd-2-yl)-2, 5-diphenylt-entrazolium bromide (MTT) assay, and the result showed very low cytoxicity of the conjugate.