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Issue 3, 2014
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A digital microfluidic electrochemical immunoassay

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Abstract

Digital microfluidics (DMF) has emerged as a popular format for implementing quantitative immunoassays for diagnostic biomarkers. All previous reports of such assays have relied on optical detection; here, we introduce the first digital microfluidic immunoassay relying on electrochemical detection. In this system, an indium tin oxide (ITO) based DMF top plate was modified to include gold sensing electrodes and silver counter/pseudoreference electrodes suitable for in-line amperometric measurements. A thyroid stimulating hormone (TSH) immunoassay procedure was developed relying on magnetic microparticles conjugated with primary antibody (Ab1). Antigen molecules are captured followed by capture of a secondary antibody (Ab2) conjugated with horseradish peroxidase enzyme (HRP). HRP catalyzes the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) which can be detected amperometrically. The limit of detection of the technique (2.4 μIU mL−1) is compatible with clinical applications; moreover, the simplicity and the small size of the detector suggest utility in the future for portable analysis.

Graphical abstract: A digital microfluidic electrochemical immunoassay

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Publication details

The article was received on 18 Sep 2013, accepted on 13 Nov 2013 and first published on 02 Dec 2013


Article type: Paper
DOI: 10.1039/C3LC51063H
Citation: Lab Chip, 2014,14, 547-554
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    A digital microfluidic electrochemical immunoassay

    M. H. Shamsi, K. Choi, A. H. C. Ng and A. R. Wheeler, Lab Chip, 2014, 14, 547
    DOI: 10.1039/C3LC51063H

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