【作者】 翁亚军；

【导师】 黄楠；

【作者基本信息】 西南交通大学 ， 材料学， 2008， 博士

【摘要】 提高与血液接触生物材料的血液相容性是一项重要的课题,通过在材料表面固定抗凝生物分子即表面生物化改性有望改善表面的抗凝血性能。本文选择具有较好生物相容性的Ti-O薄膜作为改性基础,采用三种不同的改性方法在其表面固定生物分子。首先研究了Ti-O薄膜结构对磷酸化学吸附的影响,并通过常用的硅烷化方法在磷酸化的Ti-O薄膜表面固定生物分子;其次,从获得稳定的生物化改性表面出发,研究了通过膦酸单分子自组装层和光化学方法在Ti-O薄膜表面分别固定肝素获得抗凝活性表面,固定白蛋白获得惰性表面,固定明胶获得仿生化表面;最后尝试了通过生物素-亲和素识别的方式在Ti-O薄膜表面构建肝素单层或多层膜。综合采用傅立叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、水接触角分析、荧光标记、表面轮廓分析、染色分析等方法对改性前后薄膜的成分和性质进行了定性和定量表征。通过体外的血小板粘附实验、APTT实验、材料表面纤维蛋白原变性检测、细胞培养实验和动物体内植入实验来研究改性前后材料表面的血液相容性以及内皮细胞相容性。主要结果如下:1.Ti-O薄膜的结构对磷酸化学吸附有较大的影响。相对金红石晶型薄膜,磷酸更容易在锐钛矿晶型薄膜表面化学吸附,磷酸在金红石晶型薄膜表面主要形成双齿配位结合,在锐钛矿晶型薄膜表面主要形成单齿配位结合。通过磷酸化学吸附和硅烷化方法在薄膜表面固定的生物分子层不稳定,主要的原因是中间连接层的硅烷化表面不断水解的原因。2.3-氨丙基膦酸能在Ti-O薄膜表面形成稳定的单分子自组装层。进一步通过光化学方法在膦酸自组装表面固定生物分子,获得的生物化层在PBS中浸泡时前1～3天有部分生物分子的释放,随后稳定。固定肝素的有效密度为1.2μg/cm~2,固定明胶的有效密度为2.3μg/cm~2。研究结果显示,固定肝素获得的抗凝活性表面和固定白蛋白获得的惰性表面能明显地抑制纤维蛋白原在材料表面变性,以及抑制血小板的粘附和聚集的功能。通过掩蔽曝光方式制备了图形化固定生物分子的表面。血小板在图形化固定肝素或白蛋白的表面具有图形化的分布,其粘附和活化主要集中在没有固定生物分子的微区,证实了通过该方法固定的肝素或白蛋白能有效抑制血小板的粘附。动物体内初步实验结果显示所获得肝素和白蛋白的改性表面具有优良的抗凝血性能。固定明胶获得的仿生化表面虽然具有优良的内皮细胞相容性,但由于增加了纤维蛋白原的变性程度和促进了血小板在表面的粘附,因此血液相容性较差。3.通过生物素-亲和素扩展体系能在Ti-O薄膜表面构建肝素单层或多层膜。生物素修饰肝素的比活力随着生物素修饰率的增加而降低,B-hepⅠ的比活力为原肝素活力的72%,B-hepⅡ比活力为原肝素活力的60%。肝素多层膜具有抑制血小板粘附和聚集的性能,随着肝素多层膜的增加,APTT时间先增加后趋于稳定。更多还原

【Abstract】 It is a significant work to improve the blood compatibility of blood-contacting biomaterials. A promising method is by antithrombotic biomolecules immobilization on the biomaterial surfaces. In this paper, Ti-O thin films were used as the substrate and were modified by various biomolecule immobilization through three methods. Firstly, the influence of the Ti-O film structure on the surface H₃PO₄ chemisorption on the Ti-O surface was studied, and biomolecule immobilization on Ti-O film was achieved by further silanization via chemisorption of H₃PO₄ interface. Sencondly, in order to obtain a stable surface, a self-assembling monolayer of alkylphosphonic acid on Ti-O film was prepared and different biomolecules were then further immobilized by photochemical methods, e.g., heparin was immobilized to obtain an active antithrombotic surface, bovine serum albumin （BSA） was immobilized to obtain an inert surface and gelatin was used to obtain a biomimetic surface. Finally, it was tried to construct heparinylated monolayer or multilayer on the Ti-O films through biotin-avidin biorecognition. The chemical composition and surface property of Ti-O film and the biomolecule immobilized Ti-O film were qualitatively and quantitatively characterized using Fourier transform infrared spectroscopy （FTIR）, X-ray photoelectron spectroscopy （XPS）, water contact angle analysis, fluorescence labeling method, surface profile analysis and staining methods. The blood compatibility and cell compatibility were investigated using in vitro platelet adhesion experiment, APTT test, evaluation of the denatured fibrinogen on surfaces, cell culture and in vivo implantation test. The following conclusions are obtained according to the results coming from the research mentioned above.1. The structure of Ti-O thin film has significant influence on the chemisorption of H₃PO₄ on the Ti-O surface. It is beneficial for the H3PO4 chemisorption on the surface when anatase Ti-O film acts as the substrate compared with rutile Ti-O film. The results reveal the dominating monodentate coordination of phosphoric acid to anatase Ti-O film and bidentate coordination to rutile Ti-O film. Since the middle layer of silane hydrolyzes continuously, immobilized biomolecules on the Ti-O film are unstable by the method of silanization via chemisorption of H3PO4 interface.2. A stable organic monolayer can be obtained by 3-aminopropylphosphonic acid （APP） self assembling on Ti-O film. Biomolecules were immobilized further by photochemical method on the APP modified surface. Some biomolecules were released in the first 3 days when incubation in phosphate buffer solution （PBS）, and after that it was stable. The effective surface density of immobilized heparin is 1.2μg/cm², and that of immobilized gelatin is 2.3μg/cm². It showed active antithrombotic surface by immobilization of heparin and inert surface by immobilization of BSA both have the effects on inhibiting fibrinogen denaturation and decreasing platelet adhesion and aggregation on the surfaces. Biomolecule patterned surface was obtained by using a photomask when irradiating. Platelet adhesion on the patterned surface displayed a patterned distribution, and it mainly aggregated on the non-biomolecule immobilized region which identifies the immobilized heparin or BSA indeed has the ability of inhibiting platelet from adhering on the surface. In addition, the preliminary in vivo evaluation also showed the modified surfaces have good anticoagulant properties. Gelatin immobilized biomimetic surface has good cell compatibility, while it increases the fibrinogen denaturation and platelet adhesion on the surface.3. Heparinylated monolayer or multilayer on the Ti-O films was constructed through biotin-avidin biorecognition. The activity of the biotinylated heparin decreases with the increase of biotinylated modification ratio. B-hepI has 72% activity of the virgin heparin, and B-hepII has only 60%. Heparinylated multilayer has the properties of inhibiting platelet adhesion and aggregation. APTT increases with the first several layers of heparin and then it trends to be stable with the following increase of layers.更多还原