Electrochemical Detection of Thiols with a Coenzyme Pyrroloquinoline Quinone Modified Electrode

Abstract

A modified electrode sensor for the detection of thiols is described. The sensor was constructed by incorporation of the coenzyme pyrroloquinoline quinone (PQQ) into a polypyrrole (PPy) film on a glassy carbon electrode substrate by the electropolymerization of pyrrole in the presence of PQQ. The electrochemical properties of entrapped PQQ in the PPy film were influenced by the applied potential during electropolymerization and by film thickness, both of which were optimized to yield a stable and reproducible response for entrapped PQQ. The PQQ/ PPy sensor was utilized for the amperometric detection of cysteine, homocysteine, penicillamine, N-acetylcysteine, and glutathione. The response for each thiol in pH 8.42 borate buffer was found to be linear with detection limits (S/N = 3) ranging from 13.2 microM for glutathione to 63.7 nM for cysteine with sensitivities of 0.023 nA/microM and 4.71 nA/microM, respectively. The response and detection limits were found to be sensitive to the nature of the thiol and the solution pH. Furthermore, in the presence of dopamine, ascorbic acid, or uric acid, the pH-dependent redox potential of the PQQ catalyst allows tuning of the detection potential to enhance the selectivity for thiols over these potential electroactive interferences.

The Electrochemical Behavior of Au/AuNPs/PNA/ZnSe-QD/ACA Electrode Towards CySH Oxidation

“…In addition, there have been continuous researches for fabrication of new electrode materials for developing new sensitive and selective electrochemical biosensors for the detection of the trace amounts of biomolecules [1][2][3]. Sulfur-containing amino acids, such as homocysteine (HCySH) and L-cysteine (CySH) play crucial roles in biological systems for the diagnosis of disease states [4,5]. CySH is known as an active site in the catalytic function of certain enzymes called CySH proteases and its deficiency is involved in slowed growth, hair depigmentation, edema, lethargy, liver damage, muscle and fat loss, skin lesions, and weakness.…”

Tendências em modificação de eletrodos amperométricos para aplicações eletroanalíticas

“…Em termos analíticos, a sensibilidade ou seletividade de uma determinação deve aumentar com a utilização de um EQM para que seu emprego seja justificado. Neste trabalho são discutidos alguns métodos de preparação mais usuais de EQM, bem como algumas determinações importantes de substratos de interesse clínico 8,9 e industrial 10,11 além de uma visão geral sobre os avanços incorporados nesta área ao longo do tempo.…”

Application of β-cyclodextrin/MnFe2O4 magnetic nanoparticles as a catalyst for fast chemiluminescence determination of glutathione in human blood using luminol-diperiodatoargentate(III) System

“…Measurement of free GSH in the blood samples is essential to estimate the detoxification and redox status of cells because it has the protective role against oxidative and free radical-mediated radiation cell injury. 3 A number of methods used for the determination of GSH have been reported including enzymatic, 4 spectrophotometric, [5][6][7] high performance liquid chromatography (HPLC), 8,9 electrochemical methods [10][11][12][13][14][15][16][17][18] and chemiluminescence. [19][20][21][22][23] The spectrophotometric methods are simple but not sufficiently sensitive.…”