Phase-separated two-component self-assembled organosilane monolayers and their use in selective adsorption of a protein

Stable mixed monolayers are prepared by combining Langmuir-Blodgett (LB) deposition with self-assembly. Islands of stable organosilane monolayers are formed on mica by the LB technique and the bare surface is then employed as a substrate for further selective self-assembly. When a surface covered by octadecyltrichlorosilane (OTS) monolayer islands is exposed to a solution of 1H,1H,2H,2H-perfluorode-cyltrichlorosilane (FTS), self-assembled FTS monolayers form a continuous phase between the OTS islands. Similarly, mica surfaces covered by FTS islands can be used as substrates for self-assembly of OTS monolayers. Scanning force microscopy images of phase-separated OTS/FTS monolayers show how the composition of the monolayer and the size and surface density of the islands can be varied by controlling the conditions of deposition. Adsorption experiments with bovine serum albumin show that the protein is preferentially adsorbed on the CH3-terminated regions of the patterned monolayers.