Issue 1, 2018

On-chip label-free protein analysis with downstream electrodes for direct removal of electrolysis products

Abstract

The ability to apply highly controlled electric fields within microfluidic devices is valuable as a basis for preparative and analytical processes. A challenge encountered in the context of such approaches in conductive media, including aqueous buffers, is the generation of electrolysis products at the electrode/liquid interface which can lead to contamination, perturb fluid flows and generally interfere with the measurement process. Here, we address this challenge by designing a single layer microfluidic device architecture where the electric potential is applied outside and downstream of the microfluidic device while the field is propagated back to the chip via the use of a co-flowing highly conductive electrolyte solution that forms a stable interface at the separation region of the device. The co-flowing electrolyte ensures that all the generated electrolysis products, including Joule heat and gaseous products, are flowed away from the chip without coming into contact with the analytes while the single layer fabrication process where all the structures are defined lithographically allows producing the devices in a simple yet highly reproducible manner. We demonstrate that by allowing stable and effective application of electric fields in excess of 100 V cm−1, the described platform provides the basis for rapid separation of heterogeneous mixtures of proteins and protein complexes directly in their native buffers as well as for the simultaneous quantification of their charge states. We illustrate this by probing the interactions in a mixture of an amyloid forming protein, amyloid-β, and a molecular chaperone, Brichos, known to inhibit the process of amyloid formation. The availability of a platform for applying stable electric fields and its compatibility with single-layer soft-lithography processes opens up the possibility of separating and analysing a wide range of molecules on chip, including those with similar electrophoretic mobilities.

Graphical abstract: On-chip label-free protein analysis with downstream electrodes for direct removal of electrolysis products

Supplementary files

Article information

Article type
Paper
Submitted
28 jul 2017
Accepted
18 aug 2017
First published
01 dec 2017
This article is Open Access
Creative Commons BY license

Lab Chip, 2018,18, 162-170

On-chip label-free protein analysis with downstream electrodes for direct removal of electrolysis products

K. L. Saar, Y. Zhang, T. Müller, C. P. Kumar, S. Devenish, A. Lynn, U. Łapińska, X. Yang, S. Linse and T. P. J. Knowles, Lab Chip, 2018, 18, 162 DOI: 10.1039/C7LC00797C

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