An investigation into the critical tension of electroporation in anionic lipid vesicles

Irreversible electroporation (IRE) is a technique for the disruption of localized cells or vesicles by a series of short and high-frequency electric pulses which has been used for tissue ablation and treatment in certain diseases. It is well reported that IRE induces lateral tension in the membranes of giant unilamellar vesicles (GUVs). The GUVs are prepared by a mixture of anionic lipid dioleoylphosphatidylglycerol (DOPG) and neutral lipid dioleoylphosphatidylcholine (DOPC) using the natural swelling method. Here the influence of DOPG mole fraction, X_DOPG, on the critical tension of electroporation in GUVs has been investigated in sodium chloride-containing PIPES buffer. The critical tension decreases from 9.0 ± 0.3 to 6.0 ± 0.2 mN/m with the increase of X_DOPG from 0.0 to 0.60 in the membranes of GUVs. Hence an increase in X_DOPG greatly decreases the mechanical stability of membranes. We develop a theoretical equation that fits the X_DOPG dependent normalized critical tension, and obtain a binding constant for the lipid-ion interaction of 0.75 M^-1. The decrease in the energy barrier for formation of the nano-size nascent or prepore state, due to the increase in X_DOPG, is the main factor explaining the decrease in critical tension of electroporation in vesicles.