Improved Sensitivity and Selectivity for the Redox Potentiometric Measurement of Biological Redox Molecules Using Nafion-Coated Platinum Decorated Nanoporous Gold Electrodes

Abstract

Sensitivity and selectivity are two important figures of merit in analytical measurements, but in redox potentiometry, they are often limited. In this study, we describe how the potentiometric sensitivity and selectivity can be improved using nanoporous gold (NPG) electrodes with hydrogen peroxide, dopamine, ascorbic acid, and a mixture of dopamine and ascorbic acid as the test analytes. The results show that the addition of platinum (Pt) to the nanoporous framework significantly improves electrode sensitivity for the analytes studied. Furthermore, it was only possible to potentiometrically detect hydrogen peroxide at the NPG-Pt electrodes. To further improve sensitivity and also impart some selectivity, the electrodes were spin-coated with Nafion. The addition of Nafion shifts the open-circuit potential to more positive values, increases sensitivity by almost a factor of 2, and imparts selectivity to the surface for the analysis of mixtures. Collectively, this works shows the promise of Pt-decorated nanoporous electrodes coupled with a Nafion film to improve the overall performance of redox potentiometry in analytical science.