ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Preparation of an easy and low-cost electrochemical sensor for cysteine detection based on over-oxidized poly (thiophene) modified gold electrode

Nihal Ermiş

Department of Fundamental Sciences, Faculty of Engineering, Samsun University, Samsun, Turkey

E-mail: nihal.ermis@samsun.edu.tr

Received: 25 March 2021  Accepted: 23 June 2021

Abstract:

Cysteine (Cys) is a non-essential, sulphur-containing amino acid. The disulfide bonds of cysteine amino acids strengthen tertiary and quarternary structures of a protein. Besides, cysteine plays an important role in immune system and prevents damages caused by radicals due to its antioxidant feature. In the study, a gold electrode was modified for cysteine determination. First, thiophene was electropolymerized on the gold electrode to form poly(thiophene) polymeric film. After that, poly(thiophene) was overoxidized under constant potential to obtain stronger voltammetric response for cysteine. The obtained overoxidized poly(thiophene) electrode was characterized electochemically with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The effects of various optimized parameters such as pH, scan rate (ν) and monomer concentration were investigated to evaluate the performance of synthesized electrochemical sensor. A linear response of Cys concentration in the range of 0.5–15 µM with a limit of detection (LOD) of 0.05 µM were obtained under these optimized conditions.

Keywords: Cysteine; Poly(thiophene); Overoxidized poly(thiophene); Square wave voltammetry; Electrochemical sensor development

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01751-3

Chemical Papers 75 (11) 5719–5728 (2021)