【作者】 谭庆刚；

【导师】 沈家骢； 计剑；

【作者基本信息】 浙江大学 ， 材料学， 2005， 博士

【摘要】 本文围绕着介入治疗装置材料表面凝血与抗凝血及药物涂层的基本问题,采用超分子静电自组装技术在医用316L不锈钢上构建了抗凝血生物分子多层膜表面:通过调节组装多层膜的分子结构设计了抗凝血和抗菌协同作用的表面;利用壳聚糖pH值响应性引起的去质子化效应获得了药物控释涂层;通过调节组装分子获得了具有指数增长的自组装多层膜,并探索了其在药物控释中的应用。 静电自组装和抗凝血生物分子表面固定研究从血液相容性表面设计思想出发,将层层自组装超分子技术应用到介入医用材料的表面设计与修饰中,成功地制备了含有白蛋白的生物惰性多层膜和含有肝素的抗凝血生物活性多层膜表面。 在316L不锈钢表面预先吸附一层聚阳离子聚乙烯亚氨而引入正电荷,然后通过白蛋白和聚乙烯亚氨的层层组装构建多层膜.用~125I放射标记白蛋白的方法和电化学阻抗法跟踪了层层组装过程。放射标记实验和电化学阻抗测试研究表明聚乙烯亚氨和白蛋白组装呈线性关系增长。而原子力表征显示通过控制组装层数可以制备致密的白蛋白多层膜涂层,稳定性实验研究显示多层膜在PBS内稳定存在,40天内仍有超过90%的白蛋白存在。体外血小板粘附实验表明这种惰性蛋白的涂层大大提高了316L不锈钢表面血液相容性。 研究采用聚乙烯亚氨和抗凝血活性肝素在316L不锈钢表面交替组装成功的固定了肝素多层膜。采用接触角和电化学阻抗实验对其组装过程进行了跟踪。X光电子能谱(XPS)和反射吸收红外光谱测试也表明316L不锈钢表面成功地固定了肝素分子。电化学阻抗和接触角测试表明316L不锈钢表面的肝素多层膜具有良好的稳定性。体外复钙化时间和血小板粘附实验结果表明含有肝素的多层膜涂层大大提高了3 16L不锈钢表面抗凝血性。静电自组装这种工艺简单、不依赖基材形状的温和的表面固定技术为可工业实现的介入治疗表面抗凝血设计手段提供了一种新途径。生物分子静电自组装与协同效应研究 研究采用抗凝血肝素和具有抗菌功能的壳聚糖交替组装构建具有协同抗菌和抗凝血性能的多层膜。石英微天平跟踪了在不同酸性pH值下组装的壳聚糖/肝素多层膜,并用接触角测量和紫外测试研究了环境pH值变化对多层膜表面性能的影响。结果表明壳聚糖/肝素具有很好的自组装性,形成的多层膜更多还原

【Abstract】 Electrostatic self-assembly was explored to develop multilayer film coating with anti-coagulation, anti-bactreial and drug delivery properties.Construction of Anticoagulant biomolecular Multilayer Films via Electrostatic Self-assembly Technique — The electrostatic self-assembly method was used to design and modify the interventional therapeutic material surface. The albumin bioinert multilayer and heparin bioactive multilayer film coatings were designed with electrostatic layer-by-layer （LBL） supramolecular assembly method for the anticaogulant, respectively.The positive charge was induced onto biomedical 316Lstainless steel surface by adsorption of a layer of cationic polyethylenimine （PEI）. The positive charged 316Lstainless steel sheet was alternatively dipped into bovine serum albumin （1mg/mL） and PEI （1mg/mL） PBS solutions to construct multilayer film. The process of electrostatic self-assembly of PEI/albumin was monitored by ¹²⁵I radio labeled method, electrochemical impendence spectroscopy （EIS）. The atomic force microscopy （AFM） results indicated the densely albumin coating on biomedical 316Lstainless steel could be gained with simple control the number of assembly. The EIS data revealed that the multilayer coating was stable in tris-HCI （pH 7.35） buffer solution for 21 days. The ¹²⁵I radio labeled method indicated that less than 10% albumin was eluted by PBS in 40days. The static platelet adhesion indicated that the PEI/albumin deposited stainless steel could resist the platelet adhesion effectively.The LBL self-assembly of heparin and PEI was used to construct bioactive anti-coaulation multilayer coating. The contact angle and electrochemical impendence spectroscopy （EIS） were used to monitor that layer-by-layer assembled process. The reflection absorption spectra （RAS） and x-ray photoelectron spectroscopy （XPS） data confirmed that heparin molecule was successfully immobilized onto 316Lstainless steel. The EIS data and contact angle test revealed that the PEI/heparin multilayer films were stable in tris-HCI （pH 7.35） buffer solution for 21 days. The static plateletadhesion and static clotting time experiments indicated that the heparin terminated PEI/heparin multilayer films deposited stainless steel could resist the platelet adhesion and prolong the static clotting time effectively. Such an easy processing and shape-independent method may have good potential for the construction anticoagulant surface of cardiovascular devices.Construction of collaborated anticoagulant and anti-bacterial multilayer film via Electrostatic Self-assembly Technique—The anti-bacterial chitosan and anticoagulant heparin were explored to construct collaborated anticoagulant and anti-bacterial multilayer film. Layer-by-layer assembled chitosan and heparin at different pH were monitored by Quartz Crystal Microbalance （QCM）. The wettability, dye binding ability of the chitosan terminated heparin/chitosan multilayer films varied with environment pH was investigated by contact angle measurements and UV observation. The results indicated when the heparin/chitosan multilayer film prepared at low pH contacted with related high environment pH, the chitosan occurred to deionization. The dionization of chitosan led to some excess free unpaired anionic group, which paired with ionized amino group of chitosan molecular at prepared conditions. The excess free unpaired anionic group would penetrate onto the chitosan layer with that the interpenetration of chitosan and heparin layers. The penetration of free anionic group resulted in that the chitosan terminated film showed some heparin performance and presented collaborated chitosan and heparin performance. The collaborated surface property of chitosan/heparin multilayer film was controlled by the degree of deionization of chitosan and the interepentration between chitosan and heparin molecules. The lower assembly pH led to stronger interepentration and had higher deionization of chitosan/heparin film at physiological environment （pH 7.4）. These led to the chitosan terminated chitosan/heparin multilayer film present stronger heparin performance. The dye adsorption test indicated that the free anionic group in deionized chitosan/heparin multilayer film could adsorb a large amout of cation and showed pH-dependent loading. In vitro anticoagulant and anti-bacterial tests indicated the deionized chitosan/heparin clearly showed collaborated anti-bacterial and anticoagulant properties. Thecollaborated anticoagulant and anti-bacterial of chitosan/heparin multilayer film with drug loading capabilities may have good potential for fabrication of biomedical device coating.Construction of Drug Delivery Multilayer Film Coatings via Chitosan Deionization—According to the revelation of deionization effect on chitosan/heparin multilayer film drug loading, In this section, a common strong polyanion （poly （sodium 4-styrenesulfonate） （PSS）） was used to assemble multilayer film with chitosan at pH 2.0:2.0 for detailed study of the deionization of chitosan effect on model drug loading and releasing behavior.The contact angle and UV-vis sepecrroscopy testes indicated that the PSS/chitosan multilayer film prepared at pH 2.0:2.0 could come into being free sulfate group when the multilayer film contacted with high environment pH and resulted in deioniztion of chitosan. The free sulfate group could be used to improve cationic drug loading. The salts of loading solution shielded the electrostatic interaction of polyelectrolyte and multilayer film swollen, hence controlled the dye loading.The buffered solution greatly increased dye release from multilayer films due to swelling. The loading pH and salt concentration had significant effects on the degree of the dye penetrating into bulk films and the methylene blue release. The controlled loading capabilities and release behavior of PSS/chitosan multilayer films by the deionization of weak polyelectrolyte demonstrated here may be useful toward drug delivery applications.Construction of Drug Delivery Coatings via Exponential Growth Multilayer Film— PEI/alginate multilayer films were studied to develop a novel exponential growth multilayer film and assess the possibility to develop drug delivery coatings. The QCM was used to monitor the assembly process, which indicated that the PEI/alginate multilayer film assembly had exponential growth behavior. The exponential growth PEI/alginate multilayer films could greatly improved the loading amount ofnegatively charged model drug Crocein Orange G in a few layers. The release study indicated that the exponential growth PEI/alginate multilayer film not only largely improved the loading amount of model drug, but also greatly prolonged the model drug release time. The multilayer film was crosslinked with CaCl2 or heating treatment, which could further prolong the model drug release time. The multilayer film with exponential growth could improve the amount of drug loading in limited layers, which perhaps break down the limitation of classical electrostatic self-assembly on drug loading and presented an inspiration for design of long-term drug release coating.更多还原