Electrochemical Studies of Inclusion Complex Formed Between Glutathione and β‐cyclodextrin‐modified Carbon Electrodes and its Application for Determination of Glutathione

Abstract

In this work, the electrochemical determination of glutathione (GSH) using β‐cyclodextrin (β‐CD) modified carbon electrodes was carried out. Different methodologies were used to modify the electrodes. In the first part of this paper, we analyze and compare the ability of the electrodes to determine GSH using the different β‐CD‐modified electrodes and cyclic voltammetry. We found that the carbon paste electrode modified by potential sweeping was the best electrode for GSH determination; in addition, we found that an inclusion complex formed between β‐CD deposited on the electrode surface and GSH. The formation constant for this complex was 2498.54 M−1 at 25 °C. Furthermore, we have also calculated thermodynamic parameters for the formation of the inclusion complex. In the second part of this paper, we analyze the effect of sweep rate and pH on the determination of GSH. The best results were obtained at a rate of 50 mV s−1 and a pH of 2.2. The β‐CD‐modified carbon paste electrode exhibits a linear response in a concentration range of 20 to 157 µM with a sensitivity of 1083.65 µA mM−1cm−2 and a detection limit of 3.92 µM. Finally, the electrode was used to determine the GSH concentration in Eichhornia crassipes root extract, and the concentration determination accuracy was validated by a well‐known spectroscopic method.

Iso Points in Electrochemistry. Classification and Verification by Experiment and Theory

“…Angell and Dickinson have determined ∂ α /∂E values for the Fe 3+ /Fe 2+ and Fe(CN) 6 3− / Fe(CN) 6 4− systems in aqueous solutions at platinum and gold electrodes. Similar results one can find in papers published in 2011 and later where the same elements occur together: repeated independent scans, adsorption layer on or modification of solid electrode, and isopoints. Therefore, the experimental facts presented there can be interpreted as iap occurrence.…”

“…The occurrence of intersection points (isopoints) for ordered sets of current‐potential responses was described and discussed by several authors , and the problem is still present in the literature .…”

Photoelectrochemical sensing of glutathione using bismuth vanadate (BiVO4) decorated with polyaniline (PANI) and cadmium sulfide (CdS)

“…Glutathione (GSH) is an important tripeptide containing sulfhydryl and amide bonds, composed of g-glutamic acid, cysteine, and glycine, which is widely distributed in animal, plant, and microbial cells. 1 GSH plays a key role in many physiological and pathological processes, 2 such as antioxidants and cellular immune balance. The range of GSH in human blood is 26–34 mg per 100 g. 3 However, excess GSH can affect human health, and the imbalance of GSH can lead to various diseases such as cancer, leukocyte loss, and diabetes.…”

“…5 There have been many reports on the method of measuring GSH. The strategies include the fluorescence method, 6 high-performance liquid chromatography, 7 spectrophotometry, 8 surface-enhanced Raman scattering, 9 electrochemistry, 1,10 and capillary electrophoresis. 11 However, these methods all have at least one unwelcome limitation, such as poor qualitative ability, and being expensive and complicated.…”

“…GSH is a kind of electroactive material because it can be oxidized to glutathione disulde GSSG with the loss of two protons and two electrons. 1 The principle of PEC detection is based on the separation of electron-hole (e − -h + ) pairs to generate photocurrent, which is why photoelectrochemical sensors for detecting GSH have attracted more and more attention. 13 All kinds of materials are used for the preparation of photoelectrodes.…”