Development of Surface Nanostructure Control Method of Biomaterials by Utilizing Organosilane Monolayrs

烷基三氯硅烷、[2-(全氟辛基)乙基]三氯硅烷(FOETS)及其混合单分子膜在水相上聚合，并以共价方式固定在硅片表面。原子力显微镜(AFM)观察发现，正十八烷基三氯硅烷(OTS)/FOETS共混单分子膜形成直径约为1~2微米的圆形微区，并被无定形FOETS基质包围。(OTS/FOETS)共混单分子膜的侧向力显微镜(LFM)和扫描粘弹性显微镜(SVM)观察也可以区分结构域和基质之间的物理和力学性能的差异。烷基硅烷/正十二烷基三氯硅烷(DDTS)等烷基链长较短的共混单分子膜没有出现相分离结构，可能是由于DDTS组分结晶度不足所致。对[晶态脂肪酸(非反应性)/FOETS(反应性)]混合单分子膜的AFM观察也揭示了相分离结构。用溶剂提取混合单层中的晶态脂肪酸结构域，得到孔径约为1~2微米的FOETS单层，即(Si/FOETS)单层。用另一种有机硅烷对(Si/FOETS)的硅相进行化学吸附回填。然后，用化学吸附法制备了[(3-巯基丙基)三甲氧基硅烷(MTS)/FOETS]混合单层膜，并用牛血清白蛋白(BSA)溶液研究了混合单层膜对牛血清白蛋白(BSA)的吸附。由于牛血清白蛋白中的二硫键(-S-S-)与MTS中的SH基团发生了特异的反应，牛血清白蛋白优先吸附在MTS上。另一方面，对于(OTS/FOETS)混合单分子膜，为了减小水环境中的界面自由能，牛血清白蛋白优先吸附在FOETS基质上。

Alkyltrichlorosilanes, [2- (perfluorooctyl) ethyl] trichlorosilane (FOETS) and their mixed monolayrs were polymerized on the water subphase and were covalently immobilized onto the silicon wafer surface. Atomic force microscopic (AFM) observation of the (n-octadecyltrichlorosilane (OTS) /FOETS) mixed monolayr revealed that the crystalline OTS formed circular domains of ca. 1-2 mum in diameter, which were surrounded by an amorphous FOETS matrix. Lateral force microscopic (LFM) and scanning viscoelastic microscopic (SVM) observations of the (OTS/FOETS) mixed monolayr could also distinguish the difference in the physical and mechanical properties between domain and matrix. The (alkylsilane/FOETS) mixed monolayrs with shorter alkyl chain such as n-dodecyltrichlorosilane (DDTS) did not show the phase-separated structure maybe due to the lack in crystallinity of DDTS component. AFM observation of the [crystalline fatty acid (non reactive) /FOETS (reactive)] mixed monolayr also revealed the phase-separated structure. The crystalline fatty acid domain in the mixed monolayr was extracted by solvent and then, the monolayr of FOETS with the holes of ca. 1-2 mum in diameter, that is, the (Si/FOETS) monolayr was finally obtained. The Si phase of (Si/FOETS) was backfilled with the another organosilane by chemisorption. Then, the [(3-mercaptopropyl) trimethoxysilane (MTS) /FOETS] mixed monolayr was newly obtained by the chemisorption of MTS.The adsorption of bovine serum albumin (BSA) onto mixed monolayrs was studied by exposure of the mixed monolayrs to a BSA solution. BSA was preferentially adsorbed onto the MTS part due to a specific reaction between disulfide bond (-S-S-) in BSA and SH groups in MTS.On the other hand, in the case of (OTS/FOETS) mixed monolayr, BSA adsorbed preferentially onto the FOETS matrix in order to minimized the interfacial free energy in the aqueous environment.