Nanoparticle Translocation through Conical Nanopores: A Finite Element Study of Electrokinetic Transport

Abstract

Recent years have seen a surge of interest in nanopores because such structures show a strong potential for characterizing macromolecules, e.g., DNA. Here, the authors theoretically investigate the translocation of a spherical nanoparticle through a conical nanocapillary, by numerically solving the coupled system of electrokinetic continuum equations. Based on their findings, the authors formulate simple guidelines for obtaining the maximum current signal during the translocation event, which should be transferable to other nanopore geometries. In addition, the dependence of the signal strength on particle properties, such as surface charge and size, is evaluated. Finally, the authors identify conditions under which the translocation is prevented by the formation of a strong electroosmotic barrier and show that the particle may even become trapped at the pore orifice, without imposing an external hydrostatic pressure difference.

Regulating the aggregation of colloidal particles in an electro-osmotic micropump

“…We ensured that we obtained mesh-independent results using the meshing ap-proaches laid out in refs. 42,43 , also see Fig. S7 of the ESI † .…”

“…Lastly, Rempfer et al reported the use of a microcapillary pipette to concentrate l-phage DNA at the tip of, and its subsequent delivery into, the capillary using a combination of electro-osmotic flow, pressure-driven flow, and electro-phoresis. 42,43 These linear electro-osmotic and electro-phoretic effects may be enhanced by imposing a salt gradient over the pore. For example, imposing a salt gradient led to a substantial improvement of the rate of capture of DNA into a nanofabricated SiN pore.…”

“…Similarly, Stein et al 41 revealed that DNA-aggregation may be achieved through the interplay of electro-phoresis, electro-osmosis, and the unique statistical properties of confined polymers. Lastly, Rempfer et al reported the use of a microcapillary pipette to concentrate λ -phage DNA at the tip of, and its subsequent delivery into, the capillary using a combination of electro-osmotic flow, pressure-driven flow, and electro-phoresis 42,43 .…”

Tunability of Interactions Between the Core and Shell in Rattle-Type Particles Studied with Liquid-Cell Electron Microscopy

“…Due to the large slopes in ion concentration near the charged surfaces, a ne mapped mesh was applied from the boundary of the charged surface to a distance of one or two Debye lengths. 79,80 The Debye lengths for the salt concentrations under investigation, ranging from 0.5 to 250 mM, were between 15 nm and 0.5 nm. The mapped mesh was designed to be small near the surface and to expand radially outward.…”

A thermalized electrokinetics model including stochastic reactions suitable for multiscale simulations of reaction-advection-diffusion systems

“…The model is applicable in those cases where effects on the level of the individual ion can be neglected and the system can be described by continuous density fields. Since the lattice Boltzmann method can easily handle any geometry as long as it is resolved on the grid, suitable applications are found in research fields ranging from the transport of electrolytes through porous media to biomolecules and colloids in solutions containing ions [5][6][7], as well as the investigation of microfluidic mechanisms like pumps [8] or selective particle traps [9,10]. An extension of the electrokinetic model to moving colloids in binary fluid flows is also available [11].…”