A Continuous Flow-through Microfluidic Device for Electrical Lysis of Cells.

Ying-Jie Lo,U Lei

doi:10.3390/mi10040247

Abstract

In contrast to the delicate 3D electrodes in the literature, a simple flow-through device is proposed here for continuous and massive lysis of cells using electricity. The device is essentially a rectangular microchannel with a planar electrode array built on its bottom wall, actuated by alternating current (AC) voltages between neighboring electrodes, and can be incorporated easily into other biomedical systems. Human whole blood diluted 10 times with phosphate-buffered saline (about 6 × 108 cells per mL) was pumped through the device, and the cells were completely lysed within 7 s after the application of a 20 V peak-to-peak voltage at 1 MHz, up to 400 μL/hr. Electric field and Maxwell stress were calculated for assessing electrical lysis. Only the lower half-channel was exposed to an electric field exceeding the irreversible threshold value of cell electroporation (Eth2), suggesting that a cross flow, proposed here primarily as the electro-thermally induced flow, was responsible for bringing the cells in the upper half-channel downward to the lower half-channel. The Maxwell shear stress associated with Eth2 was one order of magnitude less than the threshold mechanical stresses for lysis, implying that an applied moderate mechanical stress could aid electrical lysis.

Highlights

IntroductionCell lysis, breaking down the cell envelope (membrane, and wall if it exists) and releasing its contents, is an important step for many biomedical applications and has been studied in detail for decades [1,2,3]
Cell lysis, breaking down the cell envelope and releasing its contents, is an important step for many biomedical applications and has been studied in detail for decades [1,2,3]
Cells in buffer were pumped through the device continuously using a syringe pump, and it was anticipated that all the cells would be lysed as they passed through the electrode region under proper electrical conditions, channel geometry, and volume flow rate Q

Summary

Introduction

Cell lysis, breaking down the cell envelope (membrane, and wall if it exists) and releasing its contents, is an important step for many biomedical applications and has been studied in detail for decades [1,2,3]. Chemical, and biological methods have been developed, from small (laboratory-scale; single-cell lysis) to large-scale (process-scale), for different applications. When cells are subject to a sufficiently high electric field, exceeding a threshold value, Eth, the permeability of the cell membrane is increased such that materials (chemicals, drugs, genes, etc.) can be introduced into or taken out from the cells. The cell membrane recovers, blocking the material flow again, when the electric field is turned off [5]. When the applied electric field exceeds an even higher threshold value, Eth, the membrane will not recover and the cell is ruptured [6,7]. The above reversible and irreversible processes are referred to as electroporation in the literature, and they have significant biomedical applications. Some related figures from experiments in the literature are cited below for illustration

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Methods

Conclusion