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Mediatorless Superoxide Dismutase Sensors Using Cytochrome c‐Modified Electrodes: Xanthine Oxidase Incorporated Polyion Complex Membrane for Enhanced Activity and In Vivo Analysis
Author(s) -
Gobi K. Vengatajalabathy,
Sato Yukari,
Mizutani Fumio
Publication year - 2001
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/1521-4109(200104)13:5<397::aid-elan397>3.0.co;2-b
Subject(s) - chemistry , superoxide , ascorbic acid , xanthine oxidase , cytochrome c , bilayer , superoxide dismutase , monolayer , xanthine , inorganic chemistry , membrane , biochemistry , enzyme , mitochondrion , food science
Electrochemical superoxide dismutase (SOD) sensors were prepared by using cytochrome c‐immobilized monolayers and xanthine oxidase (XOD)/cytochrome c‐bilayers. Cytochrome c was covalently immobilized on mercaptopropionic acid‐containing self‐assembled monolayers (SAMs) on gold. The rate of cytochrome c‐catalyzed oxidation of superoxide anion was affected by the structure of the SAM: the use of a mercaptopropionic acid/mercaptopropanol mixed‐SAM gave higher reaction rate than the case of pure mercaptopropionic acid SAM. For the highly‐sensitive detection of the superoxide anion generated by xanthine‐XOD enzymatic reaction, the bilayer system was suitable, as compared with the monolayer system: superoxide anion was generated near the gold electrode surface in the case of the bilayer system, which resulted in much larger anodic current response. Further, the use of a poly‐ L ‐lysine/polystyrenesulfonate‐complex as the support for XOD enabled the detection of the superoxide anion‐generation process in the presence of L ‐ascorbic acid up to 200 µM. Although L ‐ascorbic acid could scavenge superoxide anion, it cannot be permeated into the polyion complex layer. By using the bilayer‐based electrode, the activity of SOD could be measured in the presence of L ‐ascorbic acid.