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Electric pulses (EPs) are well established for manipulating both the plasma and intracellular membranes depending upon pulse duration. Conventional electroporation uses EPs with durations on the order of microseconds to milliseconds. While submicrosecond EPs can manipulate intracellular structures, they still induce membrane nanopores that can allow ion transport [1]. Recent studies have demonstrated the impact of applying EPs with alternating positive and negative polarity to cells depends strongly on the pulse duration and time between EPs [2,3]. Bipolar nanosecond EPs (NSEPs) actually induce dramatically lower effects than monopolar EPs of the same electric field amplitude and duration [2]; however, increasing either the time between EPs or EP duration results in an additive effect [3]. One hypothesis is that NSEPs induce shock waves that drive the behavior on nanosecond timescales rather than electric phenomena [2]. As a first assessment of this phenomenon, we perform molecular dynamics (MD) simulations of a typical lipid exposed to bipolar EPs. We will report the impact of membrane voltage, duration, and ion size on membrane permeabilization and ion transport for both bipolar and monopolar EPs. We will assess this electrically driven behavior in relation to the observed experimental results [2] and discuss the potential implications and contributions of other multiphysics phenomena, such as shock waves [2] and temperature gradients.
[1] T. B. Napotnik, et. al, “Effects of high voltage nanosecond electric pulses on eukaryotic cells (in vitro): A systematic review,” Bioelectrochemistry, vol. 110, pp. 1-12, 2016.
[2] C. C. Roth, et. al, “Characterization of pressure transients generated by nanosecond electrical pulse (nsEP) exposure,” Sci. Rep., vol. 5, art. no. 15063, 2015.
[3] M. B. Sano, et. al, “In-vitro bipolar nano- and microsecond electro–pulse bursts for irreversible electroporation therapies,” Bioelectrohcemistry, vol. 100, pp. 69-79, 2014.
