Amplification of Amperometric Biosensor Responses by Electrochemical Substrate Recycling. 3. Theoretical and Experimental Study of the Phenol−Polyphenol Oxidase System Immobilized in Laponite Hydrogels and Layer-by-Layer Self-Assembled Structures

Abstract

The amperometric response toward phenol of PPO-based rotating disk bioelectrodes is analyzed on the basis of a kinetic model taking into account internal and external mass transport effects and a CEC' electroenzymatic mechanism. Monophenolase activity of PPO catalyses the oxidation of phenol to o-quinone (step C). o-Quinone can then enter an amplification recycling process involving electrochemical reduction (step E) and enzymatic reoxidation (step C': catecholase activity). The rate-limiting steps such as monophenolase activity, catecholase recycling, permeability of the membrane, and activity and accessibility of the catalytic enzyme sites are theoretically considered and experimentally demonstrated for different electrode configurations including PPO immobilized in Laponite hydrogels and layer-by-layer self-assembled multilayers of PPO and poly(diallyldimethylammonium).

One layer, two layers, etc. An introduction to the EIS study of multilayer electrodes. Part 1: Theory

“…Since self-assembled polyelectrolyte multilayers [18] can be deposited on metallic surfaces (Pt, Au, glassy carbon, etc. ), it is very probable that multilayer electrodes will mark the years to come [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34].…”

“…To the best of our knowledge, only few research groups have attempted to model mass transport in multilayer electrodes and electrochemical behaviour of these electrodes [19,20,22,23,27,28,31] García-Morales et al [19,20], who considered each layer separately, a simple approach was used until now [22,23,27,28,31], which consisted in considering the multilayer electrode as a single layer-coated electrode (with an average diffusion coefficient, D, in the whole system for electroactive species). One of the two problems of such an approach is that, as shown by Bard, Savéant and co-workers approximately twenty years ago [7][8][9][10], a voltammetric study cannot lead to a separate determination of the diffusion coefficient in the film (D for a multilayer film), of the thickness of the film, and of the partition coefficient between the solution and the film (it is what we call Ômembrane model problemÕ).…”

Composite Multienzyme Amperometric Biosensors for an Improved Detection of Phenolic Compounds

“…Furthermore, the amperometric responses of the trienzyme biosensor could not be recovered by polishing from the 7 th day, thus showing this biosensor had a much shorter useful lifetime than that exhibited by the GOD-HRP biosensor. This short useful lifetime of the trienzyme electrode is even much shorter than that observed for graphite-Teflon tyrosinase biosensors, which can be attributed to the effect of H 2 O 2 on tyrosinase causing irreversible deactivation [13].…”

Neuropathy Target Esterase Biosensor

“…Tyrosinase is a copper-containing oxidase (Forzani et al, 2000;Coche-Guerente et al, 2001), which possesses two different activities, as illustrated in reaction 1.…”