On Octadecyltrichlorosilane Research Articles

Evidence for cholera aggregation on GM1-decorated lipid bilayers

The binding properties of cholera toxin B (CTB) oligomer to substrate supported membrane bilayer, containing physiologically relevant concentrations of receptor glycolipids, viz. monosialoganglioside (GM1), have been extensively studied by the atomic force microscopy (AFM). Two distinct classes of GM1 containing membrane-mimetic surfaces were prepared: supported lipid bilayer membranes (sBLMs) on freshly cleaved mica and hybrid lipid bilayer membranes (hBLMs) on octadecyltrichlorosilane (OTS) derivatized silicon substrates. On sBLMs, aggregates with a well-defined ordered arrangement of individual CTB molecules were observed at all GM1 and cholera concentrations studied. In sharp contrast, features consistent with randomly distributed adsorbed individual CTB molecules were seen on a bare mica surface. On the hBLMs, the aggregate structures were only observed when the bilayer was formed onto ordered OTS surfaces, offering continuous and defect-free lipid membrane for the lateral diffusion of GM1. Ill-packed and disordered OTS monolayers yielded a random distribution of adsorbed proteins comparable to that observed for CTB binding on bare mica substrates. These observations strongly support that the aggregation of CTB–GM1 complex is a result of the specific interaction of CTB molecules with GM1 receptors in the fluid membrane bilayers. The high mobility of GM1 allows lateral diffusion of the complex to form ordered aggregates.

Site-Selective Deposition and Micropatterning of Zirconia Thin Films on Templates of Self-Assembled Monolayers

Zirconia thin films were successfully micropatterned on octadecyltrichlorosilane (OTS)-self-assembled monolayers (SAM) in ZrOCl2⋅8H2O-ethanol solution at room temperature. OTS-SAM was modified by UV-irradiation through a photomask to change into a SAM template patterned with silanol and octadecyl groups. The films were selectively deposited in the silanol regions through hydration-alcoholysis and condensation reactions. The as-deposited film was amorphous with a complex composition, decomposed into tetragonal-zirconia at 500°C, and further transformed into monoclinic-zirconia at 600°C. The as-deposited film demonstrated a dielectric permittivity of 14 at 100kHz, but a resistivity of 3.1×1011Ωcm and a leakage current density of 9.0×10-7Acm-2 obtained for a MOS device indicated that the film quality needed to be improved.

The Effect of Surface Preparation on the Structure and Electrical Transport in an Organic Semiconductor

ABSTRACTSelf-assembled monolayers (SAMs) with a variety of structures and terminal groups were evaluated as underlayers for pentacene deposition. It was found that the most critical factor in the formation of highly oriented thin film pentacene with large grain size was the geometric structure of the monolayer. Monolayers with terminal bonds parallel to the surface produce large pentacene grains with an angular rather than the dendridic structure normally observed on octadecyltrichlorosilane (OTS) coated substrates. The grain size, X-ray scattering, carrier mobility, and current on/off ratios are all improved with monolayers of the appropriate geometry.