Enhanced Electrocatalytic Activity of Thiophene-Substituted Asymmetric Porphyrin Film for Electrochemical Determination
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OLLOID CHEMISTRY AND ELECTROCHEMISTRY
Enhanced Electrocatalytic Activity of Thiophene-Substituted Asymmetric Porphyrin Film for Electrochemical Determination of Dopamine Sadik Cogala,* and Aysegul Oksuzb a Burdur
Mehmet Akif Ersoy University, Faculty of Engineering and Architecture, Department of Polymer Engineering, Burdur, 15030 Turkey b Suleyman Demirel University, Faculty of Arts and Science, Department of Chemistry, Isparta, 32260 Turkey *e-mail: [email protected] Received December 31, 2019; revised February 12, 2020; accepted March 11, 2020
Abstract—Thiophene substituted porphyrin derivative was synthesized and investigated. The porphyrin derivative was characterized via MALDI-MS, 1H NMR, FT-IR, and cyclic voltammetry methods. The polyporpyrin (PPor) film was electrochemically deposited on a glassy carbon electrode (GCE) via cyclic voltammetry in phosphate buffer solution (PBS). The electrocatalytic activity of the polymeric porphyrin film-modified electrode (GCE-PPor) was investigated towards dopamine through differential pulse voltammetry (DPV) method. The electrochemical results revealed that GCE-PPor exhibited a better catalytic activity towards dopamine in PBS when compared to an unpolymerized porphyrin-modified electrode. The PPormodified electrode shows a sensitivity of 5.82 μA μM–1 cm–2 and low detection limit of 0.42 μM with high selectivity in the presence of ascorbic acid (AA) and uric acid (UA) as interferents. The enhancement of the electrocatalytic activity can be explained by the enhanced π-conjugation after polymerization. Keywords: porphyrin, thiophene, polymer, electrocatalytic, dopamine DOI: 10.1134/S0036024420130087
INTRODUCTION Dopamine is one of the important catecholamine neurotransmitters present in human organism and has a crucial role in functioning of central nervous and endocrine systems. Therefore, abnormal level of this compound results in several diseases including Parkinson’s syndrome, dementia, schizophrenia [1, 2]. The DA concentration is normally between 10–8 and 10–6 M in biological systems. Hence, its accurate and selective determination is of great significance for analytical applications and early diagnosis. Compared with traditional methods, electrochemical sensors have been proposed for DA determination due to their extraordinary characteristics such as high sensitivity, high selectivity, reproducibility, cost-effectiveness, portability and fast response. However, DA coexists mostly in the body fluids with other important substances such as ascorbic acid (AA) and uric acid (UA) as a purine metabolite. Since these two compounds have similar oxidation potentials to DA, their interference influences on DA determination must be taken into consideration to increase sensor selectivity. Therefore, numerous materials have been applied in electrochemical sensors for DA detection without any potential interferents.
Among various materials, porphyrins and their metal derivatives are very suitable materials for electron transfer based applications due to their large aromati
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