Molecular Dynamics Comparison of Electroporation in Water-Vacuum-Water and Lipid Bilayer System

Abstract

A recent study showed that water forms cone-like structures at a vacuum or air interface under a sufficiently high electric field [1]. This protruding water formation may be a key step in the initiation of electroporation of lipid bilayers and cell membranes. In molecular dynamics (MD) simulations of water-vacuum-water (WVW) systems, we observe the intrusion of water into the vacuum region, similar to the pore initiation stage of electropore formation in phospholipid bilayer systems [2]. Pore initialization time in WVW systems is found to decay exponentially with applied electric field, consistent with simulations of lipid bilayers [2]. Pore initialization time in WVW systems also increases exponentially with increasing vacuum gap size. We analyze pore creation, pore annihilation, and pore stabilization. By comparing the evolution of the pore radius in both systems, we can begin to quantify how water and phospholipids each contribute to the formation and stability of lipid nanopores.1. Okuno, Y., Minagawa M., Matsumoto H., and Tanioka A. 2009. Simulation study on the influence of an electric field on water evaporation. J Mol Struct 904:83-90.2. Levine, Z. A., and Vernier, P. T. 2010. Life Cycle of an Electropore: Field-Dependent and Field-Independent Steps in Pore Creation and Annihilation. J Membrane Biol 236:27-36.