Synthesis and Characterization of Amphiphilic Biomimetic Assemblies at Electrochemically Active Surfaces

We report on the synthesis and characterization of two amphiphilic biomimetic assemblies grown on electrochemically oxidized gold- and indium-doped tin oxide substrates. The molecular assemblies are bound covalently to the substrates by the reaction of the surface oxide with acid chlorides to form ester-like bonds, creating a hydrophilic region adjacent to the substrate. One assembly possesses a moiety capable of forming a second hydrophilic region with amides that can participate in a hydrogen-bonding network within the monolayer (C 6 −A−C 12 ), and the other is an aliphatic structure (tetradecane, C 14 ). These interfacial structures, presenting hydrophobic aliphatic chains to an adsorbate, constitute a useful system for the subsequent deposition of a lipid monolayer, leading to the formation of a hybrid bilayer membrane. Examination of the capacitance, cyclic voltammetry, and FTIR data for the C 6 −A−C 12 and C 14 systems demonstrates their stability and organization, while preserving some fluidlike behavior characteristic of the hydrophilic regions, essential for biomimetic applications.