Square‐wave Voltammetry of Two‐step Surface Electrode Mechanisms Coupled with Chemical Reactions – A Theoretical Overview

Abstract

Square‐wave voltammetry (SWV) of so‐called “surface redox reactions” is seen as a simple and efficient tool to quantify large number of drugs, physiologically active substances and other important chemicals. It also provides elegant methods to get access to relevant kinetic and thermodynamic parameters related to many lipophilic compounds. Moreover, with this technique we can study activity of various enzymes by exploring the “protein‐film voltammetry” set up. In this work, we focus on theoretical SWV features of four complex surface electrode mechanisms, in which the electron exchange between the working electrode and the studied redox substrate takes place in two successive steps. While we present large number of calculated square‐wave voltammograms, we give hints to recognize particular two‐step surface mechanism, but also to distinguish it from other similar mechanisms. We present plenty of relevant aspects of surface two‐step surface EE, two‐step surface ECE and surface catalytic EEC’ mechanisms. Moreover, we present for the first time a series of theoretical results related to two‐step surface EECrev mechanism (i. e. two‐step surface reaction coupled to follow‐up reversible chemical step). The simulated voltammetric patterns presented in this work can bring relevant aspects to resolve some experimental situations met in voltammetry of many redox enzymes and other important substances whose electrochemical transformation occurs in two‐steps.

Recent Advances in CRP Biosensor Based on Electrical, Electrochemical and Optical Methods

“…As no redox peak was found in the red and blue lines, it was confirmed that molybdophosphate forms redox currents due to the electron transfer of Mo. In addition, its redox activity was confirmed by square wave voltammetry (SWV) [ 67 , 68 ]. A sample without CRP and a sample with CRP were compared using the fabricated electrochemical immunosensor.…”

Simple voltammetric approach for characterization of two-step surface electrode mechanism in protein-film voltammetry

“…Since many of these enzymes can undergo electrochemical transformation via successive exchange of electrons with the working electrode, their voltammetric patterns can be exceptionally complex [1][2][3][4][5]. As it is described in [11], their complex electrochemistry can be successfully resolved by square-wave voltammetry (SWV). In the theoretical models related to the two-step successive electrode mechanisms of [11][12][13][14][15][16][17][18][19][20], it has been recently reported on reliable procedures to characterize particular electrode enzymatic mechanism, in which coupled chemical steps occur.…”

“…As it is described in [11], their complex electrochemistry can be successfully resolved by square-wave voltammetry (SWV). In the theoretical models related to the two-step successive electrode mechanisms of [11][12][13][14][15][16][17][18][19][20], it has been recently reported on reliable procedures to characterize particular electrode enzymatic mechanism, in which coupled chemical steps occur. Moreover, relatively simple methodology has been elaborated…”

“…for determination of thermodynamic and kinetic parameters relevant to both electron transfers and the coupled chemical reactions [11,[14][15][16][17][18][19][20].…”

“…When voltammetric peaks related to both electrode reaction steps of a given redox enzyme are separated for at least |150 mV|, it is easily achievable to determine all relevant kinetic and thermodynamic parameters of the two redox steps [11,[16][17][18][19]. However, if the two electron transfers take place at the same potential, the overall electrode mechanism is associated with a SW voltammogram featuring single oxidationreduction voltammetric pattern.…”