Research On The Surface Modification Of EEPTFE Artificial Small Blood Vessel With Dopamine Grafting Bivalirudin

1 Research Background and SignificanceWith the vigorous development of the social economy,people's living standards continue to improve and the medical and health care industry is improving,life expectancy is gradually extended,and the morbidity and mortality of coronary heart disease are increasing year by year.Coronary artery bypass grafting(CABG)is an important surgical procedure for the treatment of coronary atherosclerotic heart disease.Due to various reasons,it is sometimes difficult for autologous blood vessels to meet the requirements of coronary artery bypass surgery.Therefore,the development of appropriate artificial blood vessels is a solution to the problem.However,at present,the blood compatibility of small-diameter artificial blood vessels is generally poor,and the implantation of artificial small blood vessels will easily cause the stenosis and occlusion of the bridge blood vessels,which will seriously affect the surgical effect.How to improve the long-term patency rate of artificial small blood vessels has been a research hotspot.Bivalirudin is a new synthetic anticoagulant,which can bind to thrombin specifically and directly inhibit the activity of thrombin.Compared with normal heparin,direct thrombin inhibitors work rapidly without heparin-induced thrombocytopenia or other immune-mediated thrombocytopenia.At present,it has been widely used in clinic abroad and can be used as an alternative to heparin anticoagulant therapy.Grafting it on the surface of artificial small blood vessels to exert anticoagulant effect will become a new hot spot for surface modification of artificial small blood vessels.2 Research purposes2.1 Preparation of expanded polytetrafluoroethylene artificial small blood vessels coated with polydopamine grafted bivalirudin;2.2 To investigate the blood compatibility and stability of expanded polytetrafluoroethylene artificial small blood vessels coated with polydopamine grafted with bivalirudin.3 Research methods3.1 Preparation and characterization of dopamine self-polymerizing coating on the surface of expanded polytetrafluoroethylene artificial small blood vessels;3.2 Preparation and characterization of the coated polytetrafluoroethylene artificial small blood vessel surface grafted bivalirudin coating;3.3 In vitro experiments:To evaluate the blood compatibility and stability of the composite and unmodified blood vessels,platelet adhesion test,clotting time detection test were carried out respectively4 Results and discussion4.1 Water contact angle measurement is a convenient method for characterizing the surface hydrophobicity of materials.The water contact angle measurement showed that the water contact angle of the surface of the untreated artificial small blood vessel was about 92.4°,and the water contact angle of the blood vessel surface after dopamine self-polymerization formed the film was about 95.30°,which was not much changed compared with the blank group blood vessel.After the grafting of bivalirudin after dopamine self-polymerization,the water contact angle of the treated blood vessel surface decreased to about 75.5°?and the surface hydrophilicity was improved due to the introduction of a large amount hydrophilic group including hydroxyl and carboxyl groups after grafting of bivalirudin.A decrease in the water contact angle of the vascular surface of the experimental group indicates that bivalirudin has been successfully immobilized.4.2 XPS analysis showed that Cls and Ols peaks appeared in the untreated vascular group,the dopamine self-polymerization vascular group and the grafted bivalirudin vascular group,possibly due to the influence of 02 and C02 in the air;the F peaks of the latter two experimental groups.Significantly decreased,indicating that the dopamine self-polymerized film and the grafted bivalirudin coating were successfully applied to the surface of the blood vessel;the new N peak appeared in the latter two experimental groups,and the N-peak of the grafted bivalirudin group was more because the content of N element in bivalirudin was more than that of dopamine.It was determined that bivalirudin was successfully grafted onto the surface of artificial small blood vessels.4.3 The results of in vitro experiments showed that platelet adhesion was less on the surface of the modified experimental vessels,while the unmodified group was significantly more.The clotting time test showed that the modified experimental blood vessels significantly prolonged the clotting time APTT and PT compared with the unmodified blood vessels;both showed that the modified experimental blood vessels have good blood compatibility.After physical adsorption detection,activity detection after UV sterilization and post-storage activity detection,XPS results and clotting time indicated that bivalirudin was well fixed,and the stability of the grafted bivalirudin coating on the experimental blood vessel surface was good.