Dielectric Dispersion Modulated Sensing of Yeast Suspension Electroporation

Abstract

A specific pulsed electric field protocol can be used to induce electroporation. This is used in the food industry for yeast pasteurization, in laboratories for generic transfer and the medical field for cancer treatment. The sensing of electroporation can be done with simple ‘instantaneous’ voltage-current analysis. However, there are some intrinsic low-frequency phenomena superposing the electroporation current, such as electrode polarization. The biological media are non-homogeneous, giving them specific characterization in the broad frequency spectrum. For example, the cell barrier, i.e., cell membrane, causes so called β-dispersion in the frequency range of tens to thousands of kHz. Electroporation is a dynamic phenomenon characterized by altering the cell membrane permeability. In this work, we show that the impedance measurement at certain frequencies could be used to detect the occurrence of electroporation, i.e., dielectric dispersion modulated sensing. This approach may be used for the design and implementation of electroporation systems. Yeast suspension electroporation is simulated to show changes in the frequency spectrum. Moreover, the alteration depends on characteristics of the system. Three types of external buffers and their characteristics are evaluated.

A Many-Shells Model for Cell Transmembrane Potentials for Pulsed Electric Field Applications

“…The term layer is instead used when referring to any bounded or unbounded region, including the inner and external subdomains. This is made clear here as there does not appear to be an accepted meaning of the term shell, see for instance, the differing definitions in [26], [28], and [32].…”

“…To investigate the effects of the rise-time of the applied field, the wave-shaping parameters for five waveforms following the form of (24) were computed, using a swarm-like parameter [28] AND [44]. optimization algorithm.…”

“…PEF systems used in bio-extraction and food processing technologies will encounter a variety of target media, which may have vastly different characteristics. In general, changing the properties of the extracellular media will also cause changes to the properties of the other cell layers [27], [28], which must be incorporated when modelling TMPs to better reflect practical values. In this work, low (σ e = 1 mS/m), medium (σ e = 50 mS/m), and high (σ e = 0.1 S/m) conductivity external media were considered, following the strategy in [28].…”

“…In general, changing the properties of the extracellular media will also cause changes to the properties of the other cell layers [27], [28], which must be incorporated when modelling TMPs to better reflect practical values. In this work, low (σ e = 1 mS/m), medium (σ e = 50 mS/m), and high (σ e = 0.1 S/m) conductivity external media were considered, following the strategy in [28]. These may represent standard laboratory solutions such as deionized water [28], or on the higher end, certain liquid foodstuffs that may be subject to PEF treatment in the food processing industry [50].…”

“…A class of multi-shell analytical dielectric models of biological cells or microorganisms have been commonly employed, with authors incorporating a varying number of layers, e.g., in [19], [23], [26], [28], representing various combinations (where applicable) of the nucleoplasm, nuclear membrane, cytoplasm, plasma membrane, cell wall, and extracellular medium. Maxwell-Wagner theory is applied to solve for the time-dependent potential field in each dielectric layer, thereby estimating TMPs for single, isolated, cells.…”