Molecular recognition based on an electrochemical sensor of per(6-deoxy-6-thio)-β-cyclodextrin self-assembled monolayer modified gold electrode

• The β-CD-SH was self-synthesized and characterized by FTIR and NMR.
• We examined the inclusion interactions of β-CD-SH with o, m, p-ABA and d, l-Phe.
• [Fe(CN)6]3−/4−) and Fc-COOH were used as redox probes in electrochemical experiment.
• The method of gold labeling silver staining was carried out.
• The selectivity coefficient α of d, l-Phe was up to 3.64.

This paper describes the preparation and characterization of a self-assembled monolayer of per(6-deoxy-6-thio)-β-cyclodextrin (β-CD-SH) on a gold electrode surface and the study of its inclusion interactions with d- and l-phenylalanine (Phe). The β-CD-SH was self-synthesized and characterized by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR). The modified electrode surface was carefully characterized by cyclic voltammetry (CV) using potassium ferricyanide ([Fe(CN)6]3−/4−) and ferrocenecarboxylic acid (Fc-COOH) as redox probes. Phe was labeled with gold nanoparticles (n-Au-Phe), and the chiral recognition between them and β-CD-SH on the surface of an electrode was carried out. The methods of gold labeling and silver staining was strengthened by SEM. Finally, silver enhancement was monitored by differential pulse voltammetry (DPV). The DPV signal was greatly amplified by the silver atoms coated on the n-Au. The proposed method distinguished d- from l-Phe with an enantioselectivity coefficient of 3.64. The association constants of o-, m- and p-ABA with β-CD-SH at pH 4.0 were calculated to be 2.84 × 104, 1.94 × 104, and 3.43 × 105 mol−1 L, respectively.