Effects of electrically-induced constant tension on giant unilamellar vesicles using irreversible electroporation.

Stretching in membranes of cells and vesicles plays important roles in various physiological and physicochemical phenomena. Irreversible electroporation (IRE) is the irreversible permeabilization of the membrane through the application of a series of electrical field pulses of micro- to millisecond duration. IRE induces lateral tension due to stretching in the membranes of giant unilamellar vesicles (GUVs). However, the effects of electrically induced (i.e., IRE) constant tension in the membranes of GUVs have not been investigated yet in detail. To explore the effects of electrically induced tension on GUVs, firstly a microcontroller-based IRE technique is developed which produces electric field pulses (332 V/cm) with pulse width 200 µs. Then the electrodeformation, electrofusion and membrane rupture of GUVs are investigated at various constant tensions in which the membranes of GUVs are composed of dioleoylphosphatidylglycerol (DOPG) and dioleoylphosphatidylcholine (DOPC). Stochastic electropore formation is observed in the membranes at an electrically induced constant tension in which the probability of pore formation is increased with the increase of tension from 2.5 to 7.0 mN/m. The results of pore formation at different electrically-induced constant tensions are in agreement with those reported for mechanically-induced constant tension. The decrease in the energy barrier of the pre-pore state due to the increase of electrically-induced tension is the main factor increasing the probability of electropore formation. These investigations help to provide an understanding of the complex behavior of cells/vesicles in electric field pulses and can form the basis for practical applications in biomedical technology.