title: Effect of surface coverage of gold(111) electrode with cysteine on the chiral discrimination of DOPA.
abstract: The enantioselectivity imparted to a gold electrode by modifying its surface with a self-assembled monolayer (SAM) of cysteine (Cys) was investigated for the electrochemical redox reaction of 3,4-dihydroxyphenylalanine (DOPA). A cyclic voltammetric study of the redox reaction revealed that the enantioselectivity was determined by the surface coverage of the gold electrode with Cys molecules. The electrode modified with approximately 1.8 x 10(14) Cys molecules cm(-2) exhibited enantioselectivity in the voltammogram for the oxidation and reduction of DOPA, while the voltammograms obtained by the electrodes with either more or less surface coverages did not exhibit significant enantioselectivity. It is suggested that the accessibility of DOPA to that area of the gold surface which is not blocked by Cys molecules at an optimum surface coverage, is required for the enantioselective redox reaction of DOPA to proceed.
authors.affiliation: Department of Applied Chemistry, School of Science and Engineering, Waseda University, Shinjuku, Tokyo, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Matsunaga
authors.forename: Takuya
authors.initials: T
authors.lastname: Nakanishi
authors.forename: Toru
authors.initials: T
authors.lastname: Asahi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Osaka
mesh_terms: D003545:Cysteine / Q000737:chemistry*; D004295:Dihydroxyphenylalanine / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D010084:Oxidation-Reduction; D013237:Stereoisomerism; D013499:Surface Properties
chemical_list: D004295:Dihydroxyphenylalanine; D006046:Gold; D003545:Cysteine