Thermoelectric Properties of Fe0.2Co3.8Sb12-xTex ... - Physics

Molecular dynamics simulation of electroporation of lipid bilayer membrane
Amit Kumar Majhi, V. Venkataraman, Prabal K Maiti
Department of Physics, Indian Institute of Science Bangalore, India, 560012.
Abstract
MD Simulation [1] has been performed using NAMD and VMD [2-4] to determine the pore
formation time scale for different applied fields and analyzed the movement of ions across the
electroporated lipid bilayer membrane. In addition, we have also studied the closing dynamics of
a pore when the field is switched off. The MD simulation has been performed for a total of 100
ns in presence of KCl solution of 0.2 M concentration in the water layer with different electric
fields ranging from 0.2 V/nm to 1 V/nm to elucidate the pore formation mechanism. The field is
always applied along the z-axis (perpendicular to the lipid layer) after 4 ns of equilibration. We
find that a pore formation starts at different time depending on the strength of applied fields. For
example, the pore formation starts 1ns after the application of an electric field of 0.4 V/nm but
for a field of 1V/nm pore formation starts after 0.2ns. Once a pore appears on the membrane it
expands quickly but if the field is switched off the pore reseals back but at slower speed. We
have also calculated ionic current as a function of time for different applied fields. When the
field is just turned on, the current does not flow at all but after some time it increases sharply.
This sharp rise coincides with the formation of the pore. The magnitude of the ionic current
through the membrane is found to be 10-20 nA. Pore formation mainly depends on the
magnitude of the field which indicates the increase in conductivity of the membrane with
application of electric field.
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