The role of lipid oxidation on electrical properties of planar lipid bilayers and its importance for understanding electroporation.

Electroporation is a useful tool for the manipulation with the cell membrane permeability. Underlying physicochemical processes taking place at the molecular level during electroporation are relatively well studied. However, various processes remain unknown, one of them is lipid oxidation, a chain reaction that causes degradation of lipids, and might explain the long-lasting membrane permeability after the electric field has ceased. The aim of our study was to observe the differences in the electrical properties of planar lipid bilayers, as in vitro cell membrane models, due to lipid oxidation. Phospholipids were chemically oxidized and oxidation products were analysed using mass spectrometry. Electrical properties, resistance R (Ω) and capacitance C (F) were measured using an LCR meter. Using a previously developed measuring device, a linear increasing signal was applied to a stable bilayer in order to measure its breakdown voltage Ubr (V) and lifetime tbr (µs). We observed an increase in conductance and capacitance of the oxidized planar lipid bilayers when compared to their non-oxidized counterparts. With increasing lipid oxidation, the core of the bilayer becomes more polar, and consequently more permeable. Our findings can explain the long-lasting permeability of the cell membrane after electroporation.