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Microfabricated Amperometric Cells for Multicomponent Analysis
Author(s) -
Liu Ying,
Gyurcsányi Róbert E.,
Jágerszki Gyula,
DeNuzzio John D.,
Lindner Ernő
Publication year - 2009
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/elan.200904614
Subject(s) - microelectrode , scanning electrochemical microscopy , chemistry , chronoamperometry , ascorbic acid , glucose oxidase , electrochemistry , amperometry , electrode , immobilized enzyme , enzyme , chromatography , adsorption , biochemistry , organic chemistry , cyclic voltammetry , food science
Towards the development of multianalyte electrochemical immunoassays three individually addressable microelectrode array (MEA) type working electrodes and a reference electrode were integrated into a 4 μL volume, planar electrochemical cell. To model the simultaneous determination of multiple antigens in the cell with enzyme linked immunosorbent assays (ELISAs) glucose oxidase (GOx), alkaline phosphatase (ALP), and β‐galactosidase (β‐GAL) were immobilized site specifically onto the individual MEA surfaces and the biocatalitic activity of these surface confined enzymes were evaluated by measuring the products of the enzyme catalyzed reactions directly on the gold MEA surfaces by chronoamperometry or by imaging the enzyme patterned microelectrode array surfaces by Scanning Electrochemical Microscopy (SECM). ALP and β‐GAL were selected as model enzymes because they are the most commonly used enzymes labels in ELISAs. In these measurements glucose, ascorbic acid phosphate (AAP), and p ‐aminophenyl‐β‐ D ‐galactopyranoside (PAPG) served as enzyme substrates, respectively. The electrochemical surface area of the gold MEAs did not change during the multistep immobilization process. All enzyme modified MEAs presented selective and proportional responses to their substrates and the response characteristics of the enzyme modified sensors were identical in separate and simultaneous calibration protocols, i.e., there was no cross‐contamination between the closely placed MEAs. The SECM images of the enzyme patterned MEA surfaces suggest that nonspecific adsorption is negligible on the insulating polyimide surface of the MEA separating the individual microelectrode sites.