Thermal Shock Response of Yeast Cells Characterised by Dielectrophoresis Force Measurement

Abstract

Dielectrophoresis is an electric force experienced by particles subjected to non-uniform electric fields. Recently, several technologies have been developed focused on the use of dielectrophoretic force (DEP) to manipulate and detect cells. On the other hand, there is no such great development in the field of DEP-based cell discrimination methods. Despite the demand for methods to differentiate biological cell states, most DEP developed methods have been focused on differentiation through geometric parameters. The novelty of the present work relies upon the point that a DEP force cell measurement is used as a discrimination method, capable of detecting heat killed yeast cells from the alive ones. Thermal treatment is used as an example of different biological state of cells. It comes from the fact that biological properties have their reflection in the electric properties of the particle, in this case a yeast cell. To demonstrate such capability of the method, 279 heat-killed cells were measured and compared with alive cells data from the literature. For each cell, six speeds were taken at different points in its trajectory inside a variable non-uniform electric field. The electric parameters in cell wall conductivity, cell membrane conductivity, cell membrane permittivity of the yeast cell from bibliography explains the DEP experimental force measured. Finally, alive and heat-treated cells were distinguished based on that measure. Our results can be explained through the well-known damage of cell structure characteristics of heat-killed cells.

Analysis of microorganisms with nonlinear electrokinetic microsystems

“…have found and recorded the appropriate ranges and conditions for an array of distinct models for determining zeta potentials of microorganisms by establishing where common bioparticles lie and the appropriate applicable model [30]. Researchers today are working hard still on the yeast cell model for experiments concerned with cell viability [31,33,65]. The reason for such an emphasis on this experiment model is two‐fold: yeast is a viable model capable of offering predictive data for the limits of the technology, because it was the model organisms used by Pohl et al.…”

“…Mentioned previously, yeast cells provide a great basis for the testing of novel EK techniques, specifically when the extended use may apply to other types of prokaryotic or eukaryotic cells. Recent DEP studies for lab‐on‐a‐chip technology and integrated system designs have the common theme of using yeast as a model organism with great interest in cell response to thermal shock and viability as well as differentiation in ratchet microchannels [32–34]. Many bioanalytical applications require rapid sorting of cells, which can be achieved by focusing the particles of interest into a stream within a microchannel; this is especially useful for developing integrated systems that seek to perform multiple functions within a single device.…”

“…To test cell viability, this group used a combination cell staining and a hemocytometer slide but Fernando‐Juan et al. proposed in their research that DEP could serve as a viability assessment tool [33]. Their novel technique relied on the use of DEP force as a parameter that can be used to discriminate between living and dead yeast cells (Fig.…”

“…Viability of the cells was assessed by measuring the velocity and migration of cells inside this DEP chamber. As explained in the report, heat‐threated cells (nonviable) migrated slower than viable cells [33]. They elaborated further that an advantage their DEP‐based method was its potential for automation and continuous processing; a quality heavily sought after in lab‐on‐a‐chip (LOC) technology.…”

“…(C) Scanning electron microscope images of viable and a non‐viable heat‐exposed yeast cells and Illustration of the two‐electrode system employed for the quick assessment of cell viability by Fernando‐Juan et al. Adapted with permission from [33], open access article under Creative International Public License 4.0 (2020). (D) Images portraying the before, during, and after of bacterial trapping in a gradient iDEP microfluidic device.…”