Voltage-driven translocation: Defining a capture radius

Abstract

Analyte translocation involves three phases: (i) diffusion in the loading solution; (ii) capture by the pore; (iii) threading. The capture process remains poorly characterized because it cannot easily be visualized or inferred from indirect measurements. The capture performance of a device is often described by a capture radius generally defined as the radial distance R * at which diffusion-dominated dynamics cross over to fieldinduced drift. However, this definition is rather ambiguous and the related models are usually over-simplified and studied in the steady-state limit. We investigate different approaches to defining and estimating R * for a charged particle diffusing in a liquid and attracted to the nanopore by the electric field. We present a theoretical analysis of the Péclet number as well as Monte Carlo simulations with different simulation protocols. Our analysis shows that the boundary conditions, pore size and finite experimental times all matter in the interpretation and calculation of R * .

Capture of rod-like molecules by a nanopore: Defining an “orientational capture radius”

“…Note that Θ = 1 for perfect alignment, while Θ = 0 for random orientation (r → ∞). For radial distances r much larger than the pore radius r p , the electric field outside the pore can be represented by the point-charge approximation 26,27…”

Capture and translocation of a rod-like molecule by a nanopore: orientation, charge distribution and hydrodynamics

“…We previously investigated the capture of point-like particles with a focus on the definition of the capture radius, 10 the time dependence of the capture rate, the size of the depletion zone, and the effects of the boundary conditions. 11 We also examined the orientation of rod-like polymers during capture using simple theoretical arguments and a Langevin Dynamics (LD) simulation approach 12 (thus neglecting long-ranged electrohydrodynamic interactions, EHI): this led us to introduce the concept of an orientational capture radius R θ .…”

Dielectric manipulation of polymer translocation dynamics in engineered membrane nanopores

“…Accounting for the effect of polymer conformations and steric polymer-membrane interactions on the translocation process, the connection between the dwell time and the polymer length has been initially characterized by numerical studies [21][22][23], scaling approaches [24], and the tension propagation theory [25,26]. Subsequently, the consideration of the electrostatic and non-equilibrium nature of the translocation process led to modified Smoluchowski formalisms [27][28][29][30][31][32][33] and simulation models [34][35][36][37] probing the effect of the electrostatic control parameters such as the external voltage, salt, and the acidity of the solution on the polymer capture and translocation dynamics.…”