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High-throughput microfluidic electroporation system using 3D-hydrodynamic focusing

Authors :

Zohre Nazemi Dehkordi¹ Ali Abouei Mehrizi²

1- دانشگاه تهران 2- دانشگاه تهران

Keywords :

electroporation،3D-hydrodynamic focusing،microfluidic،transfection،intracellular delivery

Abstract :

Electroporation (EP) is a well-established, non-viral method of gene delivery that transiently permeates the cell membrane in response to high fields of applied electric field. Although a successful method, traditional bulk EP systems have major limitations including uneven distribution of the electric field, limited control over exposure of individual cells, and Joule heating which can limit cell viability. Microfluidics have become a valuable tool to overcome these issues of conventional EP by allowing more precise manipulation of fluid movement, localization of the electrified field, and control over individual cells. In this work, we describe a microfluidic electroporation platform that utilizes three-dimensional hydrodynamic focusing to concentrate cells in a narrow stream of fluid measuring 20 x 20 µm at the center of the channel. The vertical and horizontal sheath flow provides orthogonal flow confinement which provides uniform exposure of each cell to the applied electric field. Our electroporation platform has embedded planar electrodes beneath the sheath layers so that the electric field is localized across the focused cell stream while minimizing direct interaction of the electrodes with the cells. Based on numerical simulations in COMSOL Multiphysics it is predicted that flow confinement is stable; concentration profiles developed appropriately; and electric field strengths will be sufficient and under the optimal electroporation window (300–800 V/cm) at an applied voltage below 2 V. The design will provide consistent exposure times on the millisecond time-scale, which is appropriate for mammalian cell electroporation, while avoiding unwanted effects like Joule heating, electrolysis, and pH changes. In comparison to previously documented devices, the system presented has increased field uniformity, lower operating voltages and has better scalability for ongoing flow processes. These results are indicative of the promise that the combination of 3D hydrodynamic focusing and low-voltage microfluidic electroporation has in furthering intracellular delivery for cell therapy production and drug screening, as well as single cell analyzers.