Translocation of Charged Polymers through a Nanopore in Monovalent and Divalent Salt Solutions: A Scaling Study Exploring over the Entire Driving Force Regimes

Abstract

Langevin dynamics simulations are performed to study polyelectrolytes driven through a nanopore in monovalent and divalent salt solutions. The driving electric field E is applied inside the pore, and the strength is varied to cover the four characteristic force regimes depicted by a rederived scaling theory, namely the unbiased (UB) regime, the weakly-driven (WD) regime, the strongly-driven trumpet (SD(T)) regime and the strongly-driven isoflux (SD(I)) regime. By changing the chain length N, the mean translocation time is studied under the scaling form ⟨ τ ⟩ ∼ N α E − δ . The exponents α and δ are calculated in each force regime for the two studied salt cases. Both of them are found to vary with E and N and, hence, are not universal in the parameter’s space. We further investigate the diffusion behavior of translocation. The subdiffusion exponent γ p is extracted. The three essential exponents ν s , q, z p are then obtained from the simulations. Together with γ p , the validness of the scaling theory is verified. Through a comparison with experiments, the location of a usual experimental condition on the scaling plot is pinpointed.

Polyelectrolyte Translocation through a Corrugated Nanopore

“…It is estimated that the chain velocity inside the pore needs to be reduced by ≈3 orders of magnitude to facilitate reliable detection. [7,8] The techniques that have been proposed to remedy this problem include separately altering the physical [9,10] and chemical [11][12][13][14][15] properties of the electrolyte solution on the cis and trans sides, tuning the polymer-pore interactions [13,15,16] and manipulating the pore geometry. [17][18][19] The last two strategies are the focus of the present computational study.…”

Star Polymer Translocation into a Spheroidal Cavity

“…The phenomenon of polymer translocation through a nanopore is of fundamental scientific and technological importance. [1][2][3] There is a large volume of literature [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] discussing various aspects of linear polymer translocation, which is reasonably well understood by now. However, considerably less attention has been paid to the effect of polymer architecture upon the translocation dynamics.…”

Macromolecule Translocation in a Nanopore: Center of Mass Drift–Diffusion over an Entropic Barrier

“…Previous theoretical approaches to understand the translocation of a polymer chain can be categorized into two broad categories: (i) phenomenological or scaling-based theories (27)(28)(29)(30)(31)(32) and (ii) microscopic or free energy-based theories (33)(34)(35)(36)(37)(38)(39)(40)(41). In many of the phenomenological theories, translocation proceeds due to tension propagation along the chain.…”

“…In many of the phenomenological theories, translocation proceeds due to tension propagation along the chain. Furthermore, polymer statistics are incorporated through the so-called tension blobs (27,(29)(30)(31)(32). While this and other related approaches have some qualitative agreement with experiments, direct quantitative comparisons are difficult due to undetermined prefactors in scaling relations.…”

“…Second, what is the proper dynamical coefficient (diffusion constant) for the translocation coordinate? Previous work debates various answers to these questions, but mostly in an ad hoc manner (26,32,35). Furthermore, recent simulations indicate the importance of including proper hydrodynamic effects in order to predict the translocation behavior found in experiments (28,(42)(43)(44).…”