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PubMed · 15113686

Microbead-based electrochemical immunoassay with interdigitated array electrodes.

Jennifer H Thomas·Sang Kyung Kim·Peter J Hesketh·H Brian Halsall·William R Heineman
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Abstract

The objective of this study was to develop a sensitive and miniaturized immunoassay by coupling a microbead-based immunoassay with an interdigitated array (IDA) electrode. An IDA electrode amplifies the signal by recycling an electrochemically redox-reversible molecule. The microfabricated platinum electrodes had 25 pairs of electrodes with 1.6-microm gaps and 2.4-microm widths. An enzyme-labeled sandwich immunoassay on paramagnetic microbeads with mouse IgG as the analyte and beta-galactosidase as the enzyme label was used as the model system. beta-Galactosidase converted p-aminophenyl beta-D-galactopyranoside to p-aminophenol (PAP). This enzyme reaction was measured continuously by positioning the microbeads near the electrode surface with a magnet. Electrochemical recycling occurred with PAP oxidation to p-quinone imine (PQI) at +290 mV followed by PQI reduction to PAP at -300 mV vs Ag/AgCl. Dual-electrode detection amplified the signal fourfold compared to single-electrode detection, and the recycling efficiency reached 87%. A calibration curve of PAP concentration vs anodic current was linear between 10(-4) and 10(-6)M. A signal from 1000 beads in a 20-microL drop was detectable and the immunoassay was complete within 10 min with a detection limit of 3.5x10(-15)mol mouse IgG.

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AminophenolsAnimalsCalibrationElectrochemistryElectrodesIminesImmunoassayImmunoenzyme TechniquesImmunoglobulin GMiceMicrochemistryOxidation-ReductionQuinonesTime Factorsbeta-GalactosidaseJournal ArticleResearch Support, Non-U.S. Gov't

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BibTeXRIS

Jennifer H Thomas, Sang Kyung Kim, Peter J Hesketh, H Brian Halsall, William R Heineman. 2004-05-15. Microbead-based electrochemical immunoassay with interdigitated array electrodes.. https://doi.org/10.1016/j.ab.2004.02.020

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