Kinetic characterization of the effects of organic solvents on the performance of a peroxidase‐modified electrode in detecting peroxides, thiourea and ethylenethiourea

Abstract

Horseradish peroxidase (HRP) modified electrodes were constructed by entrapping the enzyme in an Eastman AQ 55D polymer. The biosensor detects butanone peroxide (BTP) as a substrate, and thiourea (THU) and ethylenethiourea (ETU) as HRP inhibitors. The kinetic parameters for this sensor in organic media such as I,,,,, and K for BTP detection and K for ETU and THU detection were evaluated. The differences in the values of these parameters were explained in terms of the physico-chemical properties of the organic reaction media. A possible solvent-induced deviation of ithe biosensor behavior from Michaelis-Menten kinetics in the detection of ETU and THU was evaluated using the Hill analysis. The least deviation was observed in acetonitrile. Spectroelectrochemistry was also used to qualitatively assess solvent-HRP, BTP-HRP and inhibitor-HRP interactions.

Reproducible reduction signal of organic hydroperoxides at an in situ electrodeposited iron microelectrode, due to the reconstitution of the active surface of the electrode

“…However, the reduction of these molecules suffers from high overvoltages either at Hg, platinum or glassy carbon electrodes and in some cases the reduction is not observable [12,13]; for example, tert-butyl hydroperoxide and cumyl hydroperoxide are not reducible at glassy carbon electrodes in aqueous and mixed aqueous-organic media [12]. To solve this problem, chemically [13][14][15][16][17] and enzymatically [18][19][20][21][22][23][24] modified electrodes have been designed using the principle of supported redox catalysis. However, the main problem of such electrodes is their lack of stability and most of the enzymatically-modified electrodes are subject to rapid denaturation in organic solvents [22,24].…”

“…To solve this problem, chemically [13][14][15][16][17] and enzymatically [18][19][20][21][22][23][24] modified electrodes have been designed using the principle of supported redox catalysis. However, the main problem of such electrodes is their lack of stability and most of the enzymatically-modified electrodes are subject to rapid denaturation in organic solvents [22,24]. To our knowledge, electrocatalysis has scarcely been investigated.…”

Pure Organic Phase Phenol Biosensor Based on Tyrosinase Entrapped in a Vapor Deposited Titania Sol‐Gel Membrane

“…Additionally, the solvent viscosity (h) and dielectric constant (x) influence the substrate diffusion. Low 1/hx value results in a low frictional force between the solvent and substrate and brings a fast diffusion of substrate [24]. In biosensor construction, we aim to a high sensitivity and fast response.…”

Organic phase enzyme electrodes

“…Besides, the substrate diffusion is influenced by the viscosity (h) and the dielectric constant (e) of the solvent. The higher 1/eh factor, the greater is the diffusion constant of the analyte (Adeyoju et al, 1995).…”