Exploring multi-step glucose oxidation kinetics at GOx-functionalized nanotextured gold surfaces with differential impedimetric technique

Abstract

For a few past years, we can observe the enormous growth of investigations related to ultrasensitive electrochemical sensors capable of reliable determination of important body parameters and analytes. Utilized procedures rely on standard electrochemical methods, demanding electrode polarization, and information about the initial characteristics of the working electrode. More and more complex electrode materials are characterized however their electrochemical response is not fully understood or defined, affecting data reproducibility.Herein, we propose a novel protocol utilizing dynamic electrochemical impedance spectroscopy in galvanostatic mode (g-DEIS) to verify the sensor performance. The protocol was applied to study the response of Ti-Au nanotextured electrode depending on glucose concentration changes. The g-DEIS allowed to monitor complex mechanism occurring at the electrode/electrolyte interface with the continuously dosed glucose through electric parameters derivatives in analyte content. Our studies revealed a visible increase in electrode electric heterogeneity above 1.9 mM of glucose and gold nanoparticles’ oxidation above 3.8 mM, both influencing electrode kinetics. The results were confirmed using supporting cyclic voltammetry and x-ray photoelectron spectroscopy studies. The proposed protocol’s unique features could significantly spread further application of targetable biosensors for real-time diagnostics.