Controlling polymer capture and translocation by electrostatic polymer-pore interactions

Abstract

Polymer translocation experiments typically involve anionic polyelectrolytes such as DNA molecules driven through negatively charged nanopores. Quantitative modelling of polymer capture to the nanopore followed by translocation therefore necessitates the consideration of the electrostatic barrier resulting from like-charge polymer-pore interactions. To this end, in this work we couple mean-field level electrohydrodynamic equations with the Smoluchowski formalism to characterize the interplay between the electrostatic barrier, the electrophoretic drift, and the electro-osmotic liquid flow. In particular, we find that due to distinct ion density regimes where the salt screening of the drift and barrier effects occur, there exists a characteristic salt concentration maximizing the probability of barrier-limited polymer capture into the pore. We also show that in the barrierdominated regime, the polymer translocation time τ increases exponentially with the membrane charge and decays exponentially fast with the pore radius and the salt concentration. These results suggest that the alteration of these parameters in the barrier-driven regime can be an efficient way to control the duration of the translocation process and facilitate more accurate measurements of the ionic current signal in the pore.

Theoretical Modeling of Polymer Translocation: From the Electrohydrodynamics of Short Polymers to the Fluctuating Long Polymers

“…Section II A reviews the electrohydrodynamic formalism of polymer translocation introduced in Refs. [28,31]. In Sec.…”

“…Appendix A: Coefficients of the average velocity vp in Eqs. (28) and (30) We report here the coefficients of the average polymer translocation velocity in Eqs. (28) and (30).…”

pH-mediated regulation of polymer transport through SiN pores

“…(1)-(2) characterized by a uniform flux J(z p , t) = J 0 , with the fixed density condition at the pore entrance c(z p = 0) = c cis and an absorbing boundary at the pore exit c(z p = L p + L m ) = 0. The translocation rate defined as R p ≡ J 0 /c cis reads [13] R p = D b…”

“…Thus, we will solve this equation within an improved Donnan approximation that was introduced in Ref. [13]. The Donnan approach was shown to be accurate even in the regime of dilute salt ρ b = 0.01 M and strong surface charge σ m = 1 e/nm 2 ≈ 160 mC/m 2 located well beyond the linearized PB regime.…”

Enhanced polymer capture speed and extended translocation time in pressure-solvation traps

“…Then in Ref. [38], we incorporated into the electrohydrodynamic transport model of Ref. [27] the repulsive barrier originating from electrostatic polymer-pore interactions at the MF-level.…”