Wang Anfeng, Cao Ting, Tang Haiying, Liang Xuemei, Salley Steven O, Ng K Y Simon
Department of Chemical Engineering and Materials Science, Wayne State University, 5050 Anthony Wayne Drive, Detroit, MI 48202, USA.
Colloids Surf B Biointerfaces. 2005 Jul 10;43(3-4):245-55. doi: 10.1016/j.colsurfb.2005.04.015.
Heparin was covalently immobilized onto a silicon surface by two different methods, carbodiimide-based immobilization and photo-immobilization. In the former method, a (3-aminopropyl) trimethoxysilane (APTMS) self-assembled monolayer (SAM) or multilayer was first coated onto the silicon surface as the bridging layer, and heparin was then attached to the surface in the presence of water-soluble carbodiimide. In the latter method, an octadecyltrichlorosilane (OTS) SAM was coated on the silicon surface as the bridging layer, and heparin was modified by attaching photosensitive aryl azide groups. Upon UV illumination, the modified heparin was then covalently immobilized onto the surface. The hydrophilicity of the silicon surface changed after each coating step, and heparin aggregates on APTMS SAM and OTS SAM were observed by atomic force microscopy (AFM). In vitro haemocompatibility assays demonstrated that the deposition of APTMS SAM, APTMS multilayer and OTS SAM enhanced the silicon's haemocompatibility, which was further enhanced by the heparin immobilization. There is no evident distinction regarding the haemocompatibility between the heparin-immobilized surfaces by both methods. However, heparin on silicon with APTMS SAM and multilayer as the bridging layers is very unstable when tested in vitro with a saline solution at 37 degrees C, due to the instability of APTMS SAM and multilayer on silicon. Meanwhile, photo-immobilized heparin on silicon with OTS SAM as the bridging layer showed superb stability.
肝素通过两种不同方法共价固定在硅表面，即基于碳二亚胺的固定法和光固定法。在前一种方法中，首先将（3-氨丙基）三甲氧基硅烷（APTMS）自组装单层（SAM）或多层膜作为桥接层涂覆在硅表面，然后在水溶性碳二亚胺存在下将肝素连接到表面。在后一种方法中，将十八烷基三氯硅烷（OTS）SAM作为桥接层涂覆在硅表面，并且通过连接光敏芳基叠氮基团对肝素进行修饰。在紫外线照射下，然后将修饰后的肝素共价固定在表面上。在每个涂覆步骤后硅表面的亲水性发生变化，并且通过原子力显微镜（AFM）观察到APTMS SAM和OTS SAM上的肝素聚集体。体外血液相容性试验表明，APTMS SAM、APTMS多层膜和OTS SAM的沉积增强了硅的血液相容性，肝素固定进一步增强了这种相容性。两种方法固定肝素的表面在血液相容性方面没有明显区别。然而，由于APTMS SAM和多层膜在硅上的不稳定性，当在37℃的盐溶液中进行体外测试时，以APTMS SAM和多层膜作为桥接层的硅上的肝素非常不稳定。同时，以OTS SAM作为桥接层的硅上光固定的肝素表现出极好的稳定性。
