Electrochemical Characterization of Modified Glassy Carbon Electrodes for Non-Enzymatic Glucose Sensors

Abstract

The diversity of materials proposed for non-enzymatic glucose detection and the lack of standardized protocols for assessing sensor performance have caused considerable confusion in the field. Therefore, methods for pre-evaluation of working electrodes, which will enable their conscious design, are currently intensively sought. Our approach involved comprehensive morphologic and structural characterization of copper sulfides as well as drop-casted suspensions based on three different polymers—cationic chitosan, anionic Nafion, and nonionic polyvinylpyrrolidone (PVP). For this purpose, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy were applied. Subsequently, comparative studies of electrochemical properties of bare glassy carbon electrode (GCE), polymer- and copper sulfides/polymer-modified GCEs were performed using electrochemical impedance spectroscopy (EIS) and voltammetry. The results from EIS provided an explanation for the enhanced analytical performance of Cu-PVP/GCE over chitosan- and Nafion-based electrodes. Moreover, it was found that the pH of the electrolyte significantly affects the electrocatalytic behavior of copper sulfides, indicating the importance of OHads in the detection mechanism. Additionally, diffusion was denoted as a limiting step in the irreversible electrooxidation process that occurs in the proposed system.

Simple Fluorescence Sensing Approach for Selective Detection of Fe3+ Ions: Live-Cell Imaging and Logic Gate Functioning

“…Glassy carbon (GC) and platinum electrodes served as the working and counter electrodes, respectively. 33 On the bare GC, no characteristic redox peaks were observed. From the cyclic voltammogram of the modified electrode (GC/APSB), one oxidation peak was observed for the sensor APSB (1 × 10 –5 M) at E pa = 0.255 V. On the GC/APSB, the current density of the peak was suppressed since an insulating layer of the sensor APSB was formed on the modified working electrode.…”

“…Anodic peak current was observed at a scan rate of 0.1Vs-1 with reference to an Ag/AgCl electrode. Glassy carbon (GC) and platinum electrodes served as the working and counter electrodes, respectively . On the bare GC, no characteristic redox peaks were observed.…”

Prospective Analytical Role of Sensors for Environmental Screening and Monitoring

“…With advancement in the field of nanotechnology and materials science, numerous functional nanomaterials particularly nanoparticles, quantum dots, carbon nanotubes, graphene, and other two dimensional nanomaterials, have been used to fabricate different sensing platforms for environmental applications [54]. For example, surface modification of GCE (glassy carbon electrodes) by nanomaterials helped their usage as electrochemical sensors for label-free detection [55], consuming fluorescent quantum dots or nanoparticles in fluorescent sensors results in high-performance detecting via fluorescence quenching [56], and modification of active substrates based on metallic nanoparticle could affect surface-enhanced Raman scattering detection as low as single molecule level [57]. Though, detection of real environmental samples is still not easy through applying these fabricated sensors due to limitations in rapid and in-situ operation.…”