Direct numerical simulation of electrokinetic translocation of a cylindrical particle through a nanopore using a Poisson–Boltzmann approach

Abstract

Nanopore-based sensing of single molecules is based on a detectable change in the ionic current arising from the electrokinetic translocation of individual nanoparticles through a nanopore. In this study, we propose a continuum-based model to investigate the dynamic electrokinetic translocation of a cylindrical nanoparticle through a nanopore and the corresponding ionic current response. It is the first time to simultaneously solve the Poisson-Boltzmann equation for the ionic concentrations and the electric field contributed by the surface charges of the nanopore and the nanoparticle, the Laplace equation for the externally applied electric field, and the modified Stokes equations for the flow field using an arbitrary Lagrangian-Eulerian method. Current blockade due to the particle translocation is predicted when the electric double layers (EDLs) of the particle and the nanopore are not overlapped, which is in qualitative agreement with existing experimental observations. Effects due to the electric field intensity imposed, the EDL thickness, the nanopore's surface charge, the particle's initial orientation and lateral offset from the nanopore's centerline on the particle translocation including both translation and rotation, and the ionic current response are comprehensively investigated. Under a relatively low electric field imposed, the particle experiences a significant rotation and a lateral movement. However, the particle is aligned with its longest axis parallel to the local electric field very quickly due to the dielectrophoretic effect when the external electric field is relatively high.

Single-Particle Characterization of Aβ Oligomers in Solution

“…55, 75–77, 85–87 Ai and Qian recently modeled the dynamics of nanorods (1 nm × 10 nm) approaching a nanopore under similar conditions to those reported here and demonstrated that rods will completely align with their length axis parallel to the electric field prior to entering the nanopore. 88 Furthermore, the distribution of translocation times in cluster (ii) was narrower than the distribution in cluster (i) (Figure 2B). This result suggests reduced diffusive spreading due to accelerated motion through the pore as a result of reduced viscous drag on aggregates in cluster (ii) compared to those in cluster (i) (see Supporting Information S6 for distributions of t d values in clusters i and ii).…”

Biphasic Resistive Pulses and Ion Concentration Modulation during Particle Translocation through Cylindrical Nanopores

“…30−34 The translocation of cylindrical particles was reported with a biphasic pulse at salt concentration 0.01 M and the electrokinetic motion was shown by simulation. 35,36 The cation and anion distributions were also shown in ref 35 where they are not equal to the bulk concentration. Goyal (2013) investigated gold nanoparticle translocation using silicon nitride nanopores and observed ionic current enhancement upon particle translocation in 20 mM KCl solution.…”

Numerical simulation on movement behaviours of cylindrical particles in a circulating fluidized bed

“…Cylindrical particle flow is a frequent industrial process application, for example indirect combustion of biomass straws, moulding and drying of cylindrical pills, and moulding and machining of composite materials of fibres. Many studies have shown that the gas‐solid flow characteristics involving cylindrical particles are distinctly different from those involving spherical particles . However, it is extremely difficult (if not impossible) to experimentally acquire valuable cylindrical particle flow parameters because of present limited equipment and measuring technique levels.…”