Breaking the Interface: Efficient Extraction of Magnetic Beads from Nanoliter Droplets for Automated Sequential Immunoassays


Droplet-based microfluidic systems offer a high potential for miniaturization and automation. Therefore, they are becoming an increasingly important tool in analytical chemistry, biosciences, and medicine. Heterogeneous assays commonly utilize magnetic beads as a solid phase. However, the sensitivity of state of the art microfluidic systems is limited by the high bead concentrations required for efficient extraction across the water–oil interface. Furthermore, current systems suffer from a lack of technical solutions for sequential measurements of multiple samples, limiting their throughput and capacity for automation. Taking advantage of the different wetting properties of hydrophilic and hydrophobic areas in the channels, we improve the extraction efficiency of magnetic beads from aqueous nanoliter-sized droplets by 2 orders of magnitude to the low μg/mL range. Furthermore, the introduction of a switchable magnetic trap enables repetitive capture and release of magnetic particles for sequential analysis of multiple samples, enhancing the throughput. In comparison to conventional ELISA-based sandwich immunoassays on microtiter plates, our microfluidic setup offers a 25–50-fold reduction of sample and reagent consumption with up to 50 technical replicates per sample. The enhanced sensitivity and throughput of this system open avenues for the development of automated detection of biomolecules at the nanoliter scale.


DOI: 10.1021/acs.analchem.0c00187

Projects: MESI-STRAT

Publication type: Journal

Journal: Analytical Chemistry

Citation: Anal. Chem. 92(15):10283-10290

Date Published: 4th Aug 2020

Registered Mode: by DOI

Authors: Lukas Metzler, Ulrike Rehbein, Jan-Niklas Schönberg, Thomas Brandstetter, Kathrin Thedieck, Jürgen Rühe

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Metzler, L., Rehbein, U., Schönberg, J.-N., Brandstetter, T., Thedieck, K., & Rühe, J. (2020). Breaking the Interface: Efficient Extraction of Magnetic Beads from Nanoliter Droplets for Automated Sequential Immunoassays. In Analytical Chemistry (Vol. 92, Issue 15, pp. 10283–10290). American Chemical Society (ACS).

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Created: 23rd Feb 2021 at 11:33

Last updated: 8th Dec 2022 at 18:26

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