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Issue 12, 2008
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Enabling a microfluidic immunoassay for the developing world by integration of on-card dry reagent storage

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Abstract

As part of an effort to create a point-of-care diagnostic system for the developing world, we present a microfluidic flow-through membrane immunoassay with on-card dry reagent storage. By preserving reagent function, the storage and reconstitution of anhydrous reagents enables the devices to remain viable in challenging, unregulated environmental conditions. The assay takes place on a disposable laminate card containing both a porous membrane patterned with capture molecules and a fibrous pad containing an anhydrous analyte label. To conduct the assay, the card is placed in an external pumping and imaging instrument capable of delivering sample and rehydrated reagent to the assay membrane at controlled flow rates to generate quantitative results. Using the malarial antigen Plasmodium falciparumhistidine-rich protein II (PfHRP2) as a model, we demonstrate selection of dry storage conditions, characterization of reagent rehydration, and execution of an automated on-card assay. Gold–antibody conjugates dried in a variety of sugar matrices were shown to retain 80–96% of their activity after 60 days of storage at elevated temperatures, and the release profile of the reconstituted reagent was characterized under flow in microfluidic channels. The system gave a detection limit in the sub-nanomolar range in under nine minutes, showing the potential to expand into quantitative, multi-analyte analysis of human blood samples.

Graphical abstract: Enabling a microfluidic immunoassay for the developing world by integration of on-card dry reagent storage

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Article information


Submitted
02 Jul 2008
Accepted
19 Aug 2008
First published
16 Oct 2008

Lab Chip, 2008,8, 2038-2045
Article type
Paper

Enabling a microfluidic immunoassay for the developing world by integration of on-card dry reagent storage

D. Y. Stevens, C. R. Petri, J. L. Osborn, P. Spicar-Mihalic, K. G. McKenzie and P. Yager, Lab Chip, 2008, 8, 2038
DOI: 10.1039/B811158H

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