Effects of membrane potentials on the electric field induced rupture of giant unilamellar vesicles

Abstract

All living organisms uphold a resting membrane potential across their bilayers, which are vital in several biomedical, biophysical, and biochemical processes. On the other hand, a non-thermal and minimally invasive technique, called irreversible electroporation (IRE), utilizes electrical pulses of micro to millisecond duration to ablate cancer and tumor cells at localized zones. Earlier, IRE-induced rupture (ablation) of giant unilamellar vesicles (GUVs) of size similar to cells was investigated in the absence of membrane potentials (m). In the present study, the rupture of GUVs areinvestigated and the quantitative values of the rate constant of rupture and the probability of rupture in the presence of m ranges from 0 to 90 mV by employing the IRE techniqueare determined. The membranes of GUVs were prepared using a combination of negatively charged lipid, neutral lipid, and channel-forming protein. The electric field induces lateral electric tension in the membranes of vesicles. As the m increases from 0 to 90 mV at an electric tension, 6 mN/m, the rate constant of rupture exhibits a substantial increase from (7.5  1.6)×103 to (35.6  5.5)×103 s-1. The corresponding probability of rupture also exhibits an increase from 0.40  0.05 to 0.68 ± 0.05. To determine the pore edge tension, the logarithm of the rate constant of rupture versus the inverse of the applied electric tension has been fitted with the well-known Arrhenius equation for several values of m. It is observed that the presence of m does not lead to any significant changes in the pore edge tension. The increase in rupture is reasonably explained by the decrease of the free energy barrier of a pre-pore. The change of buffer surrounding of GUVs has influenced the kinetics of rupture along with the pore edge tension. This study provides valuable findings that can enhance the utilization of IRE technique in several biomedical fields.