仿细胞膜结构聚合物的合成及其应用研究

【作者】 杨珊；

【导师】 宫永宽；

【作者基本信息】 西北大学 ， 化学， 2009， 博士

【摘要】 随着现代医学的飞速发展,如医用导管、血管支架、传感器、心脏辅助设备等各种微创介入医疗装置已广泛地应用到各种医疗技术中,极大地丰富了现代医学诊疗手段。然而在临床应用中,现有的装置依然不同程度地存在感染、凝血以及其它的免疫副反应,这些问题给患者带来极大的痛苦,增加了医疗费用,有时还需要再次手术。设计生物相容性(包括血液相容性和组织相容性)生物医用材料是解决这些问题的有效途径。不幸的是,本体性质良好又生物相容性好的材料几乎没有。由于植入体内的生物材料是表面与体内组织相接触,于是表面改性就成为了解决上述问题的关键途径。20世纪八十年代前后,同本的Nakabayashi N研究组和英国的Chapman D研究组分别较早的提出仿细胞外层膜结构进行材料表面改性的方法,即用含磷酰胆碱基团的聚合物对材料表面改性。磷酰胆碱(PC)基团是磷脂双分子层外层膜磷脂(卵磷脂)的亲水头部,研究表明,带有等量正负电荷的PC基团是血红细胞外层膜抗凝血的原因。目前,含PC基团的聚合物的研究在各个领域都迅速扩展,例如材料表面改性、药物控释、化妆品等。本论文从设计仿外层膜结构的表/界面出发,主要合成了含磷酰胆碱基团的新型可交联型聚合物涂层材料,提出仿细胞外层膜结构聚合物涂层表面结构调控及固定方法,在材料表面构建了仿细胞外层膜结构。以此为核心开展了如下的研究工作:以三氯氧磷和氯化胆碱为原料,用非均相一步法合成了含磷酰胆碱基团的活性化合物二氯磷酰胆碱,并将二氯磷酰胆碱用于玻璃的表面改性。动态接触角(DCA)和X射线光电子能谱(XPS)分析表明,二氯磷酰胆碱对玻璃表面改性成功,这为材料表面仿细胞膜结构改性提供了新途径。为深入研究二氯磷酰胆碱的合成条件及定量测定,本文改进了磷酸电位滴定法。改进的磷酸电位滴定法能够快速、准确的完成对磷酸及磷酸酯/盐混合物组分的定量分析,对磷酸酯/盐类的合成及应用具有一定的指导意义。研究了重要聚合单体2-甲基丙烯酰氧基乙基磷酰胆碱(MPC)的合成路径,对传统合成方法的实验装置进行了改进,使每步的合成产率都得到较大提高。探索了合成MPC的两条新途径,通过对合成的MPC均聚物和共聚物的元素、IR、~1H NMR进行测试,间接证明了新合成路线可行。然而,新路线合成的MPC在分离纯化方面的问题有待进一步解决。以MPC、甲基丙烯酸十八烷基酯(SMA)及可交联的γ-甲基丙烯酰氧丙基三甲氧基硅(TSMA)为单体,通过自由基引发随机聚合得到一种可交联的仿生医用涂层材料PMST。通过对PMST及系列参比聚合物进行~1H NMR、衰减全反射红外(ATR-IR)、DSC、临界胶柬浓度(CMC)、分子量等测试,选出PMST20(TSMA含量20mol%)来对盖玻片进行表面改性。分别用涂覆和LB膜方式制备涂层,重点研究了涂覆方式制备的涂层表面仿细胞外层膜结构调控及固定的方法。用表面界面张力仪、原子力显微镜(AFM)、XPS,分别对亲、疏水固定处理前后的表面进行了DCA、表面形貌、表面元素组成的测试。结果表明,亲水与疏水处理后的表面,在理化性质上存在很大差异。血小板黏附和蛋白吸附实验表明,PMST20涂层的血液相容性良好,亲水处理后的表面血液相容性更好。用涂层表面仿细胞外层膜结构调控及固定的方法,可以最大限度地发挥仿细胞膜结构聚合物的生物相容性,为提升生物医用材料及器件的应用性能提供了理论基础。另外,由于PMST含有可交联基团和亲、疏水基团,且具有较低的临界胶束浓度,可望成为制备新型稳定的高分子纳米载药胶束的新材料。更多还原

【Abstract】 With the rapid development of modern medical science, various kinds of minimally invasive interventional medical devices, such as catheters, vessel stents, sensors, heart aids and the like, have been widely applied to medical application, and have greatly enriched the treatment means of modern medicine clinics. However, when these devices come into contact with living organisms, thrombus formation, infection and other unfavorable immune responses occur sooner or later, which cause discomfort to the patient and increase the cost and, in some cases, means that more surgery is required. Biocompatibility, including blood compatibility and tissue compatibility, is the most important property that any useful biomedical material must possess. Unfortunately, it is rare that a biomaterial with good bulk properties also exhibits suitable biocompatibility. It is the surface of a biomaterial that enters into contact with living tissues when the biomaterial is placed in the body. Therefore, surface modification is a key process for biomaterials as well as devices for clinical applications. About 1980s, one of the most attractive methods of surface modification for biomaterials, "biomimicry", was proposed by Nakabayashi with his coworkers and Chapman with his coworkers. This concept involves reproducing the surface properties of the thromboresistant surfaces of blood cell membranes. This is achieved by use of chemical entities that having the structure of phosphorylcholine (PC) group. The hydrophilic zwitterionic polar PC-group is the major lipid headgroup of the extracellular lipid bilayer, which is the cause of the extracellular surfaces of blood cell membranes thromboresist. The research on PC containing polymers has been expanding rapidly in various fields, such as surface modification of biomaterials, drug delivery systems, cosmetics, and so on.In this dissertation, a novel crosslinkable terpolymer coating material bearing phosphorylcholine functionality was prepared. A method on adjustment and immobilization of biomimetic structure of surface coating was proposed and applied on surface modification in order to get a stable hydrophilic haemocompatible surface/interface. The main works are as follows.Phosphorylcholine dichloride, a useful reactive compound, was synthesized directly from phosphoryl chloride and choline chloride under anhydrous condition in a single step reaction, and was applied to modify the surface of glass. The synthetic conditions were studied by a modified potentiometric titration method here. Dynamic contact angle (DCA) measurement and X-ray photoelectron spectroscopy (XPS) analysis confirmed that a biomimetic surface was obtained successfully by grafting phosphorylcholine dichloride on glass, which provides another new way for surface modification of biomaterials. In order to study the synthetic conditions and the quantitative analysis of phosphorylcholine dichloride, the conventional potentiometric titration method on phosphoric acid was modified here. The modified potentiometric titration method is more accurate and rapid at analyzing the composition of phosphate mixture, and also helpful for searching for better synthetic conditions.2-methacryloyloxyethyl phosphorylcholine (MPC) is an important monomer. The synthetic route of MPC was studied here. The experimental apparatus of traditional synthetic route was improved here and the yield increased greatly in each step. Furthermore, two new synthetic routes of MPC were explored. The two new routes were proved feasible through the elemental analysis, IR and ~1H NMR of MPC homopolymer and copolymer. However, the difficulty in the purification of MPC obtained from the new routes still needs more effort.A novel crosslinkable phosphorylcholine based terpolymer PMST was synthesized by the radical polymerization from three kinds of monomers including the biomimetic monomer MPC, the hydrophobic monomer stearyl methacrylate (SMA), and the crosslinkable monomer trimethoxysilylpropyl methacrylate (TSMA). The random terpolymer PMST was obtained through monomer-starved technique. PMST and a series of reference polymers were characterized by determination of ~1H NMR, attenuated total reflection infrared spectroscopy (ATR-IR), differential scanning calorimeter (DSC), critical micelle concentration (CMC), matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). PMST with 20mol% TSMA in the terpolymer was chosen to prepare biomimetic crosslinkable coating. PMST was coated onto cover glass by dip-coating or Langmuir-Blodgett (LB) technique. The research was mainly focused on the surface structure and property of dip-coated film. The coating was treated in different methods in order to get a biomimetic interface structure. The structure after adjusting was fixed by crosslinking of the trimethoxysilylpropyl groups. DCA, atomic force microscope (AFM) and XPS were used to study the hydrophilicity, surface morphology, and surface elemental composition of coating, respectively. It was found that the hydrophilic surface was different from the hydrophobic one on physical and chemical properties. The platelet adhesion and protein adsorption experiments show that, the blood compatibility of the surface modified with PMST20 coating was excellent, and the hydrophilic PMST20 surface was better. The method on adjustment and immobilization of biomimetic structure of surface coating here could improve biocompatibility of the biomimetic polymers greatly, and also provide theoretical base for improving the application performance for biomedical materials and devices. In addition, PMST could be a novel material to prepare stable drug delivery polymeric nano-micelles as it was a crosslinkable amphiphilic polymer with a lower CMC.更多还原