Fabrication of a novel Ferrocene/Thionin bimediator modified electrode for the electrochemical determination of dopamine and hydrogen peroxide

Abstract

A novel bimediator compound has been synthesized by covalently linking two redox mediators and used for fabrication of bimediator modified electrode to perform electrocatalytic oxidation and reduction of substrates. Ferrocene monocarboxylic acid and thionin have been linked via amide bond using (N-3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC·HCl) and N-Hydroxy benzotriazole (HOBt) as cross-linking agents. The electrochemical characterization and surface characterization have confirmed the presence of both redox mediators in the bimediator compound on the modified electrode surface which has facilitated electron transfer between analyte and the electrode. The ferrocene has mediated electrocatalytic oxidation of dopamine at positive potentials while thionin has mediated electrocatalytic reduction of hydrogen peroxide at negative potentials. Effective utilization of this bimediator modified electrode has been examined under static and dynamic conditions by cyclic voltammetry and chronoamperometric techniques. Ferrocene has been found to oxidise dopamine at a potential of 0.35V in the concentration range of 0.569μM to 515μM with a detection limit of 0.190μM and sensitivity of 142μAmM−1cm−2 whereas thionin has been found to reduce hydrogen peroxide at a potential of −0.3V in the concentration range of 0.569μM to 785μM with a detection limit of 0.190μM and sensitivity of 128μAmM−1cm−2. This bimediator modified electrode has also been used for real sample analysis.