Abstract
Fabrication of biocompatible electrodes for the investigation of catecholamines is a known challenge. In this work, methionine was chosen as a modifier for fabrication of a biocompatible carbon paste electrode by electropolymerization, through cyclic voltammetry. The electrochemical behavior of the poly(methionine) modified carbon paste electrode was characterized by cyclic voltammetry for simultaneous determination of dopamine (DA) and uric acid (UA) in a phosphate-buffered solution at pH 7.0. In the absence of an amino acid methionine layer, the bare carbon paste electrode exhibits rather poor voltammetric signals in DA and UA in the binary mixture, with oxidation potentials of DA and UA overlapping with each other. The poly(methionine) modified carbon paste electrode exhibits good catalytic activity with noticeably different oxidation potentials of DA and UA. The experimental results closely agree with the theoretical prediction based on a Fukui function complementary to the simulated electrostatic potential maps.
Highlights
Neurotransmitters are the chemical messengers that transmit a message from one neuron to another [1]
Dopamine (DA), one of the most significant catecholamine neurotransmitters belonging to the family of excitatory chemical neurotransmitters [1,2,3], plays an important role in the proper functioning of the renal, central nervous, hormonal, and cardiovascular system [4]
Atomic coordinates for all models were constructed using MOLDEN [33] software (Gijs Schaftenaar, CMBI, Netherlands) Full geometry optimization and electrostatic potential computations of the models were carried out using density functional theory (DFT) in the Gaussian09 program [34] with a hybrid method B3LYP [35,36] for calculating exchange-correlation potential functions and 6-311G (d, p) [37,38]
Summary
Neurotransmitters are the chemical messengers that transmit a message from one neuron to another [1]. A shortage of DA in the brain is linked to aggregation of symptoms of Parkinson’s disease and other seemingly unrelated diseases, including schizophrenia and Huntington’s disease, as well as drug addiction and human immunodeficiency virus (HIV) infection [1,5,6,7,8]. The primary end product of purine metabolism, uric acid (UA), is an important antioxidant, which protects dopaminergic neurons against oxidative damage. A shortage of UA is linked to symptoms of several diseases, such as gout, hyperuricemia, and Lesch–Nyhan disease [7,8,9,10]. Many studies have been devoted to the fabrication of chemically modified electrodes for simultaneous determination of levels of DA and UA in a binary mixture [11,12], with improving selectivity and sensitivity being one of the main objectives of electroanalytical research [11,12]
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