Assessment of the electrochemical effects of pulsed electric fields in a biological cell suspension

• An experimental protocol was designed to elucidate pulsed electric field effects on the electrode/electrolyte interface.
• An electric field affects electrodes and the degree of alteration depends on the electrolyte conductivity.
• The electrochemical reaction rate depends on the initial free charges in the solution and those generated by the PEF.
• Biological cells interact with the medium and change the initial impedance of the solution even before electroporation.
• New interfaces created after electroporation lead to the impedance changes in the presence of the cell membrane pores.

Electroporation of cells is successfully used in biology, biotechnology and medicine. Practical problems still arise in the electroporation of cells in suspension. For example, the determination of cell electroporation is still a demanding and time-consuming task. Electric pulses also cause contamination of the solution by the metal released from the electrodes and create local enhancements of the electric field, leading to the occurrence of electrochemical reactions at the electrode/electrolyte interface. In our study, we investigated the possibility of assessing modifications to the cell environment caused by pulsed electric fields using electrochemical impedance spectroscopy. We designed an experimental protocol to elucidate the mechanism by which a pulsed electric field affects the electrode state in relation to different electrolyte conductivities at the interface. The results show that a pulsed electric field affects electrodes and its degree depends on the electrolyte conductivity. Evolution of the electrochemical reaction rate depends on the initial free charges and those generated by the pulsed electric field. In the presence of biological cells, the initial free charges in the medium are reduced. The electrical current path at low frequency is longer, i.e., conductivity is decreased, even in the presence of increased permeability of the cell membrane created by the pulsed electric field.