共价交联的肝素/海藻酸盐水凝胶表面修饰膨体聚四氟乙烯人工血管

背景:虽然膨体聚四氟乙烯人工血管植入体具有易于缝合、质地柔软和抗压迫等诸多优良性能,但由于血栓形成等原因,使这些材料的应用受限.为了解决前述问题,目前的工作主要集中在对现有人工血管材料表面修饰与改性上,最终使其达到血管植入的要求.目的:用共价交联的肝素-海藻酸钠水凝胶对小口径膨体聚四氟乙烯人工血管进行表面修饰和改性,考察其血液相容性和组织相容性.设计:观察性实验.单位:哈尔滨工业大学生物医学工程中心,纳米医药与生物传感器实验室.材料:实验所用直径4 mm的膨体聚四氟乙烯人工血管为W.L Gore & Associates,Inc.产品,海藻酸钠和1-乙基-3.3-二甲基氨丙基碳化二亚胺购自美国Sigma公司,肝素购于Calbiochem公司,全氟磺酸和壳聚糖购于美国Aldrich公司.人α-凝血酶和抗凝血酶Ⅲ购于Haematologic Technologies,S-2238购于Chromogenix.方法:实验于2006-05/2007-06在哈尔滨工业大学生物医学工程中心的纳米医药与生物传感器实验室完成.首先用全氟磺酸修饰膨体聚四氟乙烯表面,然后用肝素-海藻酸钠凝胶进行灌注修饰,以乙二胺为交联剂,1-乙基-3-3-二甲基氨丙基碳化二亚胺为引发剂,将多糖分子进行共价交联.用接触角表征了涂层前后人工血管表面亲水性能的变化,扫描电镜表征了材料表面形貌及血小板黏附,衰减全反射-傅立叶变换红外光谱表征了材料表面的化学结构,然后用活化部分凝血激酶时间、凝血酶原时间、溶血试验以及凝血酶失活试验表征了涂层后人工血管表面的血液相容性.主要观察指标:①接触角.②用扫描电镜表征材料表面形貌及血小板黏附情况.③衰减全反射-傅立叶变换红外光谱.④活化部分凝血激酶时间、凝血酶原时间.⑤溶血度.⑥凝血酶失活试验.结果:①修饰后的人工血管,衰减全反射-傅立叶变换红外光谱结果显示在1 626 cm-1处出现了-CO-NH-基团的峰位.②修饰后人工血管的接触角由(125±1)°降低为(84±2)°.③修饰后的人工血管,具有较长的活化部分凝血激酶时间和凝血酶原时间、较低的溶血度0.065%、较少数量的血小板黏附.④凝血酶失活实验结果显示,凝胶灌注修饰后的人工血管,对凝血酶的活性有较强的抑制作用,因此具有血栓形成的性能且稳定性好.结论:肝素-海藻酸钠凝胶修饰的膨体聚四氟乙烯具有良好血液相容性及组织相容性,可应用于小口径人工血管.

Thromboresistant surface modification of expanded polytetrafluoroethylene vascular graft by impregnating covalently crosslinked gel of heparin and alginate

BACKGROUND: The expanded polytetrafluoroethylene (ePTFE) vascular grafts hold promise for enhanced healing,extended suture retention, kink reduction and compression resistance. But thrombus formation still limits its use for revascularization of small-caliber vessels. It is the surface of ePTFE vascular graft that contacts with the blood. The current study focused on surface modification of ePTFE materials to improve its blood compatibility.OBJECTIVE: To characterize the heparin/alginate (H/A) gel modified ePTFE vascular graft and investigate the hemocompatibility and histocompatibility of the graft.DESIGN: Observation experiment.SETTING: Laboratory for Nanomedicine and Biosensor, Biomedicine Engineering Center, Harbin Institute of Technology.MATERIALS: The GORE-TEX ePTFE vascular grafts were 4 mm in internal diameter. Sodium alginate and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) were purchased from Sigma. Heparin sodium salt was obtained from Calbiochem. Nation and chitosan were purchased from Aldrich company. Human α-thrombin and AT Ⅲ were purchased from Haematologic Technologies, Inc. S-2238 was purchased from Chromogenix.METHODS: This study was performed at the Laboratory for Nanomedicine and Biosensor, Biomedicine Engineering Center, Harbin Institute of Technology between May 2006 and June 2007. The graft was first modified with Nation and then Chitosan/Nafion/Chitosan multilayer. Following the impregnation of heparin and alginate, covalent crosslinking was performed using ethylenediamine and EDC. Some characterization methods were employed: stastic water contact angle for the hydrophilicity; SEM for the surface morphology; ATR-FTIR for the surface chemical characteristics; APTT and PT,percent hemolysis and Chromogenic assay for the hemocompatibility of the ePTFE vascular graft after modification.MAIN OUTCOME MEASURES: ①Static water contact angles. ②Charactedzation of the surface morphology and platelet adhesion by SEM. ③ATR-FTIR ④APTT and PT. ⑤Percent hemolysis ⑥Chromogenic assay for heparin activity.RESULTS: ①ATR-FTIR revealed the presence of -CO-NH- at 1626 cm-1. ②The water contact angle was greatly decreased from (125±1)° to (84±2)° .③The prolonged APTT and PT, low percent hemolysis(0.065%) and low amount of platelet adhesion assay showed the H/A gel impregnated graft had good blood compatibility. ④Chromogenic assay showed the modified graft was less thrombogenic than the bare one, and the H/A coating had good stability in. PBS buffer.CONCLUSION: The H/A modified ePTFE vascular graft has great potential in applications utilizing small-diameter vascular grafts.