Cell Sorting Using Electrokinetic Deterministic Lateral Displacement.

Bao Ho,Jonas Tegenfeldt,Jason Beech

doi:10.3390/mi12010030

Abstract

We show that by combining deterministic lateral displacement (DLD) with electrokinetics, it is possible to sort cells based on differences in their membrane and/or internal structures. Using heat to deactivate cells, which change their viability and structure, we then demonstrate sorting of a mixture of viable and non-viable cells for two different cell types. For Escherichia coli, the size change due to deactivation is insufficient to allow size-based DLD separation. Our method instead leverages the considerable change in zeta potential to achieve separation at low frequency. Conversely, for Saccharomyces cerevisiae (Baker’s yeast) the heat treatment does not result in any significant change of zeta potential. Instead, we perform the sorting at higher frequency and utilize what we believe is a change in dielectrophoretic mobility for the separation. We expect our work to form a basis for the development of simple, low-cost, continuous label-free methods that can separate cells and bioparticles based on their intrinsic properties.

Highlights

While standard cell sorting schemes rely on labelling and molecular recognition events, cells have important properties for which there exist no labels
We have presented and characterized an integrated device that combines deterministic lateral displacement (DLD) and electrokinetics to sort particles based on size and on electric and dielectric properties
Since changes in viability are linked to changes in properties such as surface charge, membrane integrity, membrane conductivity, and polarizability rather than size or shape, we were able to show proof of principle of leveraging these parameters to perform viability-based separations

Summary

Introduction

While standard cell sorting schemes rely on labelling and molecular recognition events, cells have important properties for which there exist no labels. This has driven the development of microfluidics-based label-free techniques that exploit cells’ intrinsic physical properties for fractionation. Dielectrophoresis (DEP) is a well-established technique that can be used to target these types of changes It is based on the movement of particles along an electric field gradient due to their dielectric properties [10,11]. Adjusting the frequency of the applied electric field, the force can be tuned and made sensitive to the desired types of changes of the particles of interest. By adjusting the frequency of the AC voltage applied between adjacent electrodes and switching the flow and voltages, the authors

Methods

Results

Conclusion