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A Pyruvate Oxidase Electrode Based on an Electrochemically Deposited Redox Polymer
Author(s) -
Gajovic Nenad,
Habermüller Katja,
Warsinke Axel,
Schuhmann Wolfgang,
Scheller Frieder W.
Publication year - 1999
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/(sici)1521-4109(199912)11:18<1377::aid-elan1377>3.0.co;2-b
Subject(s) - redox , chemistry , polypyrrole , inorganic chemistry , thiophene , electron transfer , electrode , platinum , biosensor , amperometry , conductive polymer , polymer , electrochemistry , polymerization , photochemistry , catalysis , organic chemistry , biochemistry
A redox polymer‐modified, 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. Ag/AgCl) of Os(bipy) 2 pyCl‐modified pyrrole monomer (6×10 –3 mol L –1 ) and thiophene (1×10 –3 mol L –1 ) 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 efficient 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 0.02×10 –3 to 0.3×10 –3 mol L –1 . A sensitivity as high as 0.2 A cm –2 mol –1 L was obtained. Phosphate was measured similarly between 0.02×10 –3 and 0.5×10 –3 mol L –1 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.