Pandey Rakesh K, Suresh K A, Lakshminarayanan V
Raman Research Institute, C.V. Raman Avenue, Bangalore 560080, India.
J Colloid Interface Sci. 2007 Nov 15;315(2):528-36. doi: 10.1016/j.jcis.2007.07.044. Epub 2007 Jul 27.
We have formed the cholesterol monolayer and multilayer LB films on the self-assembled monolayers of 2-naphthalenethiol (2-NT) and thiophenol (TP) and studied the electrochemical barrier properties of these composite films using cyclic voltammetry and electrochemical impedance spectroscopy. We have also characterized the cholesterol monolayer film using grazing angle FTIR, scanning tunneling microscopy (STM) and atomic force microscopy (AFM). Cholesterol has a long hydrophobic steroid chain, which makes it a suitable candidate to assemble on the hydrophobic surfaces. We find that the highly hydrophobic surface formed by the self-assembled monolayers (SAM) of 2-NT and TP act as effective platforms for the fabrication of cholesterol monolayer and multilayer films. The STM studies show that the cholesterol monolayer films on 2-NT form striped patterns with a separation of 1.0 nm between them. The area per cholesterol molecule is observed to be 0.64 nm2 with a tilt angle of about 28.96 degrees from the surface normal. The electrochemical studies show a large increase in charge transfer resistance and lowering of interfacial capacitance due to the formation of the LB film of cholesterol. We have compared the behavior of this system with that of cholesterol monolayer and multilayers formed on the self-assembled monolayer of thiophenol.
我们已在2-萘硫醇（2-NT）和苯硫酚（TP）的自组装单分子层上形成了胆固醇单分子层和多层LB膜，并使用循环伏安法和电化学阻抗谱研究了这些复合膜的电化学阻挡性能。我们还使用掠角傅里叶变换红外光谱、扫描隧道显微镜（STM）和原子力显微镜（AFM）对胆固醇单分子层膜进行了表征。胆固醇具有一条长的疏水类固醇链，这使其成为在疏水表面组装的合适候选物。我们发现，由2-NT和TP的自组装单分子层（SAM）形成的高度疏水表面可作为制备胆固醇单分子层和多层膜的有效平台。STM研究表明，2-NT上的胆固醇单分子层膜形成条纹图案，条纹间距为1.0 nm。观察到每个胆固醇分子的面积为0.64 nm2，与表面法线的倾斜角约为28.96度。电化学研究表明，由于胆固醇LB膜的形成，电荷转移电阻大幅增加，界面电容降低。我们已将该系统的行为与在苯硫酚自组装单分子层上形成的胆固醇单分子层和多层膜的行为进行了比较。
