Cyclic Voltammetric and Electrical Impedance Spectroscopy Studies of Graphene- and Conductive Polymer–based Enzyme Electrodes

  • Nur Alya Batrisya Ismail International Islamic University Malaysia
  • Nurul Izzati Ramli International Islamic University Malaysia
  • Firdaus Abd-Wahab International Islamic University Malaysia
  • Wan Wardatul Amani Wan Salim International Islamic University Malaysia
Keywords: Cyclic voltammetry, electrical impedance spectroscopy, PEDOT, PSS, partially reduced graphene oxide, glucose oxidase, electrochemical transduction

Abstract

Screen-printed carbon electrodes (SPCEs), modified with graphene oxide and poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid (GO-PEDOT:PSS/SPCEs), and SPCEs modified with partially reduced GO and PEDOT:PSS (prGO-PEDOT:PSS/SPCEs) were studied for electrochemical transduction. Randles-Sevcik analysis showed that the prGO-PEDOT:PSS/SPCE has a higher effective surface area of 219.3 µm2in comparison to the unreduced GO-PEDOT:PSS/SPCE (87.0 µm2) and the bare SPCE (71.7 µm2). Using electrical impedance spectroscopy (EIS), we determined that the prGO-PEDOT:PSS/SPCE has a lower charge-transfer resistance (Rct) of 163.82 Ω in comparison to the GO-PEDOT:PSS/SPCE (427.87 Ω) and the bare SPCE (13.31 kΩ). Glucose oxidase (GOx) was immobilized on all electrode types, including GO/SPCE as additional control and tested with low (0.2 mM), intermediate (0.6 mM), and high (1 mM) glucose concentrations. GOx/GO/SPCEs showed the largest change in anodic peak current (Ipa), 8.5, 7.5 and 4.9 µA for low, intermediate, and high glucose concentrations, respectively. Interestingly, GOx/prGO-PEDOT:PSS/SPCEs have no change in both anodic and cathodic peak current, although they exhibit better redox capability, while GOx/SPCEs have very low Ipa. The results show that the high effective surface area and low charge-transfer resistance (Rct) of prGO-PEDOT:PSS/SPCEs do not necessarily result in a sensitive glucose sensor in cases where immobilization of enzymes on the material can affect electron transfer.

Downloads

Download data is not yet available.
Published
03-09-2019
How to Cite
Ismail, N. A. B., Ramli, N. I., Abd-Wahab, F., & Wan Salim, W. W. A. (2019). Cyclic Voltammetric and Electrical Impedance Spectroscopy Studies of Graphene- and Conductive Polymer–based Enzyme Electrodes. International Journal of Integrated Engineering, 11(3). Retrieved from https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/4541