On-chip label-free protein analysis with downstream electrodes

Kadi L. Saar, Yingbo Zhang, Thomas Müller, Challa P. Kumar, Sean Devenish, Andrew Lynn, Urszula Łapińska, Xiaoting Yang, Sara Linsed and Tuomas P. J. Knowles.

Lab Chip 2018;18;162-170

In this paper, Saar et al. demonstrate a novel microfluidic method for probing protein electrophoretic mobility and charge in solution. The unique architecture of the microfluidic device allows fields of up to 100 V/cm to be applied without adverse effect from gaseous electrolysis products. The authors use the technique to measure chaperone-fibril binding under native conditions, and achieve rapid separation in-solution of the bound vs unbound species in just a few seconds.

schematic of device used in Saar et al

Fig.1 schematic of the device used in this studySchematic of the device used in this study. (A) The electrophoresis chamber is connected to a co-flowing electrolyte solution (3M KCl) via narrow perpendicular channels that control the mass transfer of the electrolyte to the electrophoresis chamber forming a thin sheet of electrolyte at the edges of the chamber (inserts (i), (ii); visualised via the addition of trace amounts of bovine serum albumin). The electric field is applied from metal clips at the outlets of the electrolyte channels and it propagates to the electrophoresis channel along with the flowing electrolyte solution. (B) The co-flowing electrolyte solution transports the electrolysis products away from the chip while simultaneously propagating the electric field in the direction opposite to the flow back into the device.

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