Enantioselective Recognition of Proline Enantiomers Using Sulfhydryl-modified Self-assembled Gold Electrodes

Penicillamine, cysteine, and N-isobutyryl-cysteine enantiomers self-assembled gold electrodes were used for the enantioselective recognition of proline in the presence of copper(II). High stereoselectivity for proline was obtained for the D-form of the sulfhydryl compounds, particularly on the D-penicillamine-modified gold electrode. Cyclic voltammetry and electrochemical impedance spectroscopy were used to confirm the chiral discrimination of proline enantiomers on the D-penicillamine modified gold electrode in the presence of copper(II). The largest electrochemical response was obtained for D-proline for the recognition of its enantiomers, whereas small responses were obtained for the L- and D-forms of phenylalanine, tyrosine, serine, and glutamic acid. The influences of incubation time and pH for chiral ligand exchange were evaluated. This study complements and enhances applications for the recognition of amino acid enantiomers based on ligand exchange by electrochemical analysis.