A cholylglycine sensor based on 1,2-naphthoquinone-4-sulphonic acid sodium (NQS)/β-cyclodextrin-graphene oxide modified electrode

Abstract

In this paper, a novel, simple and sensitive cholylglycine (CG) electrochemical sensor was prepared based on the specific recognition of 1, 2-naphthoquinone-4-sulphonic acid sodium salt (NQS) to CG for the first time. It was constructed with β-cyclodextrin-graphene oxide (β-CD-GO) on glassy carbon electrode (GCE) and modified with NQS to obtain NQS/β-CD-GO/GCE. A decrease of the oxidation peak current of NQS arising from the specific binding of CG and NQS through a nucleophilic substitution reaction was used for indirect detection of CG. The performances of the proposed sensor were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The difference of the oxidation peak current was linear with the CG concentration in the range of 0.2-60.0 μM and the detection limit of CG was 0.061 μM. Moreover, the CG sensor showed good repeatability and high stability and has been applied to the determination of CG in human serum with satisfactory recoveries. So, a new method has been provided for detecting electrochemically inert material CG.