Microfluidic device with a push–pull sequential solution-exchange function for affinity sensing
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A simple valveless microfluidic device consisting of a reaction chamber and eight flow channels was fabricated for the detection of proteins. The efficient exchange of solutions in the reaction chamber was achieved by sequentially introducing solutions into the reaction chamber and removing them from the reaction chamber through the same flow channels. The influence of the hydrophobicity of the reaction chamber and the viscosity of a blocking solution on solution exchange was investigated. The analytical performance of the device was examined by detecting human interleukin 2 (IL-2) using a sandwich fluorescence immunoassay, with the amount of immuno-complex formed in the reaction chamber monitored by fluorescence microscopy. The approach facilitated the rapid detection of IL-2, in which the total assay time was less than 30 min. A clear dependence of fluorescence intensity on IL-2 concentration was observed over the 125 pg/mL–2.0 ng/mL range, with a detection limit of 105 pg/mL. To promote automation, a simple mechanism that exchanges solutions by the push–pull movement of a PDMS diaphragm was also demonstrated.
KeywordsValveless microfluidics Solution exchange Immunoassay Human Interleukin-2
We would like to thank Professor Masatoshi Yokokawa and Dr. Gokul Chandra Biswas of University of Tsukuba for valuable discussions.
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Conflict of interest
There are no conflicts to declare.
Supplementary material 2 (WMV 688 KB)
Supplementary material 3 (WMV 1354 KB)