Abstract

PINTO, Sandra M. et al. Electrode cleaning and reproducibility of electrical impedance measurements of HeLa cells on aqueous solution. Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2020, vol.44, n.170, pp.257-268.  Epub June 15, 2021. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.919.

Electrical impedance spectroscopy (EIS) is used to study the electrical properties of cells in suspension. Two (bipolar electrode system), three (tripolar) and four (tetrapolar) electrodes are used to measure the electrical properties of materials with tetrapolar measurements being the best option to minimize electrode polarization effects. When EIS measurements are repeated for the same sample, almost identical spectra can be expected. However, in some situations, significant differences associated with low reproducibility and repeatability are found. Herein we used HeLa cells dispersed in an aqueous solution to evaluate the effect of cleaning on the performance of gold electrodes. The surface cleaning of gold electrodes was conducted by cyclic voltammetry. We found that the impedance measuring reproducibility and repeatability are enhanced when the electrodes are cleaned. These results show that surface cleaning minimizes the contribution of electrode polarization in measurements. Additionally, a circuital model is proposed to describe the effect of untreated surfaces on electrical measurement. The circuital model confirms that the observed effect is not due to a typical polarization impedance. Rather, it is an active polarization (interfacial polarization), which occurs at low frequencies, and is independent of the frequency of the excitation signal.

Keywords : Reproducibility; Electrical impedance spectroscopy; HeLa cells; Surface phenomena; Circuital model.

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