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Paper   IPM / Nano-Sciences / 16365
School of Nano Science
  Title:   Pulling a DNA molecule through a nanopore embedded in an anionic membrane: tension propagation coupled to electrostatics
  Author(s): 
1.  Jalal Sarabadani
2.  Sahin Buyukdagli
3.  Tapio Ala-Nissila
  Status:   Published
  Journal: J. Physics: Condens. Matter
  Vol.:  32
  Year:  2020
  Pages:   385101
  Publisher(s):   IOP Publishing Ltd
  Supported by:  IPM
  Abstract:
We consider the influence of electrostatic forces on driven translocation dynamics of a flexible polyelectrolyte being pulled through a nanopore by an external force on the head monomer. To this end, we augment the iso-flux tension propagation theory with electrostatics for a negatively charged biopolymer pulled through a nanopore embedded in a similarly charged anionic membrane. We show that in the realistic case of a single-stranded DNA molecule, dilute salt conditions characterized by weak charge screening, and a negatively charged membrane, the translocation dynamics is unexpectedly accelerated despite the presence of large repulsive electrostatic interactions between the polymer coil on the cis side and the charged membrane. This is due to the rapid release of the electrostatic potential energy of the coil during translocation, leading to an effectively attractive force that assists end-driven translocation. The speedup results in non-monotonic polymer length and membrane charge dependence of the exponent alpha characterizing the translocation time tau ∝ N alpha 0 of the polymer with length N0. In the regime of long polymers N0 500, the translocation exponent exceeds its upper limit alpha = 2 previously observed for the same system without electrostatic interactions.

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