Correlation between morphology change and microwave property during single-cell electroporation

Traditionally, electroporation of biological cells is tracked by fluorescence microscopy with chemical dyes that tend to be slow and invasive. This paper reports, for the first time, electroporation tracked by real-time change in the microwave insertion loss, which is correlated with simultaneous change in cell morphology recorded through an optical microscope. The change in insertion loss was found to be faster and more abrupt than the change in cell morphology, although the latter was still faster than fluorescence microscopy. Although more work is needed to verify whether these changes correspond to a reversible electroporation or not, the present result suggests that real-time microwave characterization can be a faster and less invasive technique for early detection of electroporation. Additionally, although the electroporation is presently performed on Jurkat human lymphoma cells, it is believed that the same technique can be extended to many other types of cells.

I. Introduction

Electroporation is a convenient technique to introduce polar or charged molecules into a biological cell for drug evaluation or genetic manipulation [1]. Under a pulsed or continuous-wave (CW) electrical signal, nanometer pores can form on the cell membrane to allow molecules to diffuse in or out of the cell. The time it takes for poration varies as the effect of electrical stimulation is statistical and cumulative, and each cell is different biologically. Upon removal of the poration signal, the membrane can heal gradually. However, if the pore size or density is too high, the membrane cannot heal, the cell viability is affected, and the poration is deemed irreversible.