Electrochemical Behavior of l-Cysteine and Its Detection at Ordered Mesoporous Carbon-Modified Glassy Carbon Electrode

Abstract

In this paper, the electrochemical behavior of L-cysteine (CySH) was investigated thoroughly at an ordered mesoporous carbon-modified glassy carbon (OMC/GC) electrode. The voltammetric studies showed there were three anodic peaks for the electrooxidation of CySH in the pH range of 2.00-5.00; however, one peak disappeared above pH 5.00. This behavior has never been reported before. Through the studies of the effect of pH on the distribution fractions (delta) of the four chemical species of CySH, we conclude only CySH2+ (H3A+) and CyS- (HA-) are the electroactive substances and should be responsible for the electrooxidation of CySH. And for the first time, we successfully established the exact and systemic mechanisms based on the electroactive species to explain CySH oxidation at different pH values. On the other hand, a sensitive CySH sensor was developed based on an OMC/GC electrode, which shows a large determination range (18-2500 micromol L(-1)), a high sensitivity (23.6 microA mmol L(-1)), and a remarkably low detection limit (2.0 nmol L(-1), which is the lowest value ever reported for direct CySH determination on the electrodes) at pH 2.00. At pH 7.00, the modified electrode can be still used to readily detect CySH in the range of the physiological levels. These make OMC/GC electrode a promising candidate for efficient electrochemical sensors for the detection of CySH.

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

“…For CySH oxidation at the surface of Au/AuNPs/PNA/ZnSe-QD (Fig. 6 curve d) a possible mechanism may be as follows [26]:…”

“…Among different methodologies used, electrochemical measurements of thiols have attracted considerable interest because of their high sensitivity, simplicity, low cost and feasibility to the development in vivo sensors and chromatographic detectors [21,22]. Various chemically modified electrodes (CMEs) with electrocatalytic properties have been fabricated and applied in the detection of CySH [23][24][25][26]. The reported CMEs have their advantages and limitations in linear dynamic range, selectivity, sensitivity, detection limit and other characteristics.…”

Voltammetric Determination of Ferulic Acid by Didodecyldimethyl-ammonium Bromide/Nafion Composite Film-modified Carbon Paste Electrode

“…This could be the consequence of deprotonation involved in the oxidation process which was facilitated at higher pH values. 25 It was also found that the oxidation peak current of ferulic acid increased sharply with increasing pH from 4.0 to 5.5, and then decreased greatly as pH increasing from 5.5 to 7.0. Thus, the acetate buffer solution at pH 5.5 was chosen as the supporting electrolyte for the determination of ferulic acid.…”

Thermal and mechanical improvement of aluminum open-cells foams through electrodeposition of copper and graphene

“…Due to their advantageous characteristics, such as low production costs, wide potential window, high thermal conductivity and mechanical strength, inert electrochemistry [1], carbon materials have been widely used in many technological fields [2,3]. The advantages of carbon materials combined with those of nanostructured materials, such as carbon nanotubes [4,5], carbon nano-fibers [6], highly ordered mesoporous carbons [7,8], etc., have drawn much more attention because of their unusual electronic properties and ability to improve catalytic properties [9]. In solid materials heat is carried by acoustic phonons, which are ion-core vibrations in a crystal lattice, and electrons so that the thermal conductivity coefficient (k) is the sum of the phonon (k p ) and electron (k e ) contributions.…”