Peptide‐derived self‐assembled monolayers: Adsorption of N-stearoyl L-systeine methyl ester on gold

Abstract

The work reported herein concerns the assembly of N-stearoyl l-cysteine methyl ester [CH_3(CH_2)_(16)COCysOMe, 1] on the surface of gold. This compound serves as a simple model of a related polypeptide, which has been designed to adopt a β-sheet architecture on metallic and oxide surfaces. We describe the preparation of monolayers of 1, and characterization of these layers via ellipsometry, vibrational spectroscopy and X-ray photoelectron spectroscopy. The results are most consistent with a disordered array of the alkyl chains, in which close packing is frustated by a mismatch in the cross-sectional areas of the cysteinyl ester head group and the stearoyl chains of the thiol. Despite the disorder, the alkyl chains form a hydrophobic surface layer, with an advancing contact angle for water comparable to that observed for octadecanethiol on gold.