A Pyruvate Oxidase Electrode Based on an Electrochemically Deposited Redox Polymer

Abstract

A redox polymer-modi®ed, multilayer biosensor for the determination of pyruvate and phosphate in oxygen-free samples has been developed. The new, highly conductive redox polymer was produced by potentiostatic copolymerization (1.4 V vs. AgaAgCl) of Os(bipy) 2 pyCl-modi®ed pyrrole monomer (6610 À3 mol L À1) and thiophene (1610 À3 mol L À1) on top of a platinized glassy-carbon electrode. The redox polymer-coated platinum black layer with increased active surface area permitted the adsorption of pyruvate oxidase as the biological recognition element and ef®cient electron transfer from enzyme-bound FAD-groups to the electrode. Pyruvate was detected at anodic potentials (350±500 mV) in oxygen-free solution in the presence of phosphate as the cosubstrate with a linear range from 0.02610. A sensitivity as high as 0.2 A cm À2 mol À1 L was obtained. Phosphate was measured similarly between 0.02610 À3 and 0.5610 À3 mol L À1 in the presence of pyruvate as co-substrate. The sensitivity of the sensor dropped to about 12 % after 10 days. Since interference by ascorbate, due to the high formal potential of the used Os(bipy) 2 pyCl-group, could be a problem in real samples, coverage of the adsorbed enzyme by a polycationic size exclusion layer of polypyrrole was investigated. Compared to former enzyme electrodes utilizing pyruvate oxidase, the new approach offered an unprecedentedly high sensitivity, O 2 -and thiamindiphosphate-independent operation and presented a large step towards electrochemical pyruvate determination in vivo.

Poly(pyrrole‐co‐pyrrole‐2‐carboxylic acid)/Pyruvate Oxidase Based Biosensor for Phosphate: Determination of the Potential, and Application in Streams

“…The linear range is more wider than most of the phosphate biosensor studies. A linear range of 5–25 μM was reported for purine nucleoside phosphorylase and xanthine oxidase immobilized polypyrrole film based potentiometric biosensor , 7.5–625 μM for pyruvate oxidase immobilized nafion matrix and poly (carbamoyl) sulfonate hydrogel coated electrode , 50–400 μM for pyruvate oxidase immobilized electrode and 20–500 μM for pyruvate oxidase immobilized conductive redox polymer based amperometric biosensor .…”

Amperometric Biosensor for Choline Based on Gold Screen‐Printed Electrode Modified with Electrochemically‐Deposited Silica Biocomposite

“…There are several possible ways for the elimination of interfering influence of ascorbic acid in the literature. The semipermeable membranes on the electrode can limit the access of interfering substances to the electrode due to the size or charge of their molecules 50, 51. However, this approach often leads to the decrease of the sensitivity of the biosensor 52.…”

Polymers in biosensors

“…Cholesterol biosensors have also been constructed using polyaniline (Wang andMu 1999, Singh et al 2006). Pyruvate oxidase has been incorporated within a copolymer of a modified pyrrole monomer with thiophene and used to detect pyruvate (Gajovic et al 1999). A platinum microelectrode was used as the substrate for deposition of polypyrrole containing a three enzyme mixture (xanthine oxidase, purine nucleoside phosphorylase and adenosine deaminase), with the resultant sensor being capable of detecting adenosine at concentrations down to 100 nM (Llaudet et al 2003).…”