Differentiating Between Living and Dead Single Yeast Cells Using Broadband EIS

Research conducted at Cornell University (Ithaca, New York) has yielded a novel electrical impedance spectroscopy (EIS)-based sheathless microfluidic platform with an integrated coplanar waveguide to probe the interior of a single cell of yeast (Schizosaccharomyces pombe). The platform allows for the precise single-cell trapping through dielectrophoresis (DEP), hydrodynamic focusing, and the sensing of the cell’s electrical properties. Investigators declared that this platform may provide real-time monitoring of cellular electrical responses to chemical and physical antagonists for diagnostic purposes. A paper based on this research was published in the journal Lab on a Chip (1).

The characterization of single-cell biophysical organisms has received considerable attention among scientists seeking understanding of the mechanisms and processes taking place within them (2). The biophysical characterization of a single cell yields a wealth of information that is valuable in various fields of research such as food (3), medicine chemistry (4), biology (5), and monitoring of the environment (6).

Interest in the identification of the electric properties of cells’ electrical properties has increased recently, with a variety of methods used in the process (7). Dielectric-based spectroscopy techniques (impedance flow cytometry [IFC], for example) have been developed for the characterization of cells in a high throughput manner, including the impedance flow cytometry framework for single-cell analysis (8,9). On the other hand, impedance-based spectroscopic techniques, such as EIS, have been developed where most of the electric field passes through the cells (10).

The researchers measured the resistance of ten live and twenty dead single yeast cells, individually, while the single cell was trapped between the coplanar waveguide (CPW) signal electrodes. The team investigated the electrical properties of the membrane and cytoplasm of each cell in a wide frequency range of 30 kHz to 6 GHz non-invasively. The electrical properties of the cells were then measured through the suggested equivalent circuit simulation; the cytoplasm's small capacitance was found to be approximately 3.6 femtofarad (fF). The cell viability was successfully distinguished through impedance measurement. It was established that the resistance increased, and the capacitance decreased, for dead cells because of the diffusion of the sucrose/dextrose solution through the perforated cell membrane. Furthermore, the resistance and capacitance of the cytoplasm of the dead cell increased due to an increase in the permeability of the membrane and the influx of the surrounding media (sucrose/dextrose) to the cell cytoplasm. Noticeable differences between the viable and nonviable single yeast appeared at 3 GHz, where the capacity of the cytoplasm dominates (1).

The authors of the paper state the platform provides a fast, accurate, noninvasive, and label-free method for the characterization of a single cell, which they believe can be used for any type of cell and different electrode configurations, regardless of the shapes and geometries for cell viability discrimination, real-time single-cell monitoring, and rapid, precise single-cell analysis. The authors state that future work will focus on the EIS measurement of single-cell growth between the CPW to measure the structural changes during this period (1).

Confocal Microscopy of Fission Yeast Schizosaccharomyces pombe. © Bogdan - stock.adobe.com

References

1. Favakeh, A.; Mokhtare, A.; Asadi, M. J.; Hwang. J. C. M.; Abbaspourrad A. Label-Free Differentiation of Living versus Dead Single Yeast Cells Using Broadband Electrical Impedance Spectroscopy. Lab Chip 2025, Avance article. DOI: 10.1039/d5lc00043b

2. Schmid, A.; Kortmann, H.; Dittrich, P.S.; Blank, L. M. Chemical and Biological Single Cell Analysis. Curr. Opin. Biotechnol. 2010, 21 (1), 12–20. DOI: 10.1016/j.copbio.2010.01.007

3. Preece, E. P.; Hardy, F. J.; Moore, B. C.; Bryan, M. A Review of Microcystin Detections in Estuarine and Marine Waters: Environmental Implications and Human Health Risk. Harmful Algae 2017, 61, 31–45. DOI: 10.1016/j.hal.2016.11.006

4. Barreiros Dos Santos, M.; Queirós, R. B.; Geraldes, Á.; Marques, C.; Vilas-Boas, V.; Dieguez, L. et al. Portable Sensing System Based on Electrochemical Impedance Spectroscopy for the Simultaneous Quantification of Free and Total Microcystin-LR in Freshwaters. Biosens. Bioelectron. 2019, 142, 111550. DOI: 10.1016/j.bios.2019.111550

5. Kubitschek, H. E. Electronic Counting and Sizing of Bacteria. Nature 1958, 182 (4630), 234–235. DOI: 10.1038/182234a0

6. Grulke, D. C.; Marsh, N. A.; Hills, B. A. Experimental Air Embolism: Measurement of Microbubbles Using the Coulter Counter. Br. J. Exp. Pathol. 1973,54 (6), 884–891. https://pmc.ncbi.nlm.nih.gov/articles/PMC2072609/ (accessed 2025-02-28)

7. Mansor, M. A.; Ahmad, MR. Single Cell Electrical Characterization Techniques. Int. J. Mol. Sci. 2015, 16 (6),12686–12712. DOI: 10.3390/ijms160612686

8. Feng, Y.; Zhu, J.; Chai, H.; He, W.; Huang, L.; Wang W. Impedance-Based Multimodal Electrical-Mechanical Intrinsic Flow Cytometry. Small 2023,19 (45), e2303416. DOI: 10.1002/smll.202303416

9. Feng, Y.; Cheng, Z.; Chai, H.; He, W.; Huang, L.; Wang, W. Neural Network-Enhanced Real-Time Impedance Flow Cytometry for Single-Cell Intrinsic Characterization. Lab Chip 2022, 22(2), 240–249. DOI: 10.1039/d1lc00755f

10. Hwang, J. C. M. Label-Free Noninvasive Cell Characterization: A Methodology Using Broadband Impedance Spectroscopy. IEEE Microwave Magazine 2021, 22 (5), 78–87. DOI: 10.1109/MMM.2021.3056834