Electrodiffusiophoretic Motion of a Charged Spherical Particle in a Nanopore

Abstract

The electrodiffusiophoretic motion of a charged spherical nanoparticle in a nanopore subjected to an axial electric field and electrolyte concentration gradient has been investigated using a continuum model, composed of the Poisson-Nernst-Planck equations for the ionic mass transport and the Navier-Stokes equations for the flow field. The charged particle experiences electrophoresis in response to the imposed electric field and diffusiophoresis caused solely by the imposed concentration gradient. The diffusiophoretic motion is induced by two different mechanisms, an electrophoresis driven by the generated electric field arising from the difference of ionic diffusivities and the double layer polarization and a chemiphoresis due to the induced osmotic pressure gradient around the charged nanoparticle. The electrodiffusiophoretic motion along the axis of a nanopore is investigated as a function of the ratio of the particle size to the thickness of the electrical double layer, the imposed concentration gradient, the ratio of the surface charge density of the nanopore to that of the particle, and the type of electrolyte. Depending on the magnitude and direction of the imposed concentration gradient, one can accelerate, decelerate, and even reverse the particle's electrophoretic motion in a nanopore by the superimposed diffusiophoresis. The induced electroosmotic flow in the vicinity of the charged nanopore wall driven by both the imposed and the generated electric fields also significantly affects the electrodiffusiophoretic motion.

Diffusiophoresis of an Elongated Cylindrical Nanoparticle along the Axis of a Nanopore

“…[21, 22, 25-31, 37, 38, 40, 42] Experiments show that DNAs are often elongated or stretched during the translocation through a nanopore. [54] Motivated by the use of the diffusiophoresis to regulate DNA translocation through a nanopore for the nanopore-based DNA sequencing technology, we extend our previous analysis on diffusiophoresis of a spherical nanoparticle [44][45][46] to that of an elongated cylindrical nanoparticle along the axis of a nanopore driven by the induced electrophoresis and chemiphoresis under various conditions. The results presented are very useful in controlling the electrophoretic translocation of DNA molecules by diffusiophoresis in a nanopore-based DNA sequencing technique.…”

“…[35,41,47] The possible control of the electrophoretic motion of a spherical nanoparticle in a nanopore by the diffusiophoretic control has been theoretically demonstrated. [45,46] Recently, the regulation of DNA nanoparticle electrophoretic translocation through a nanopore by the induced diffusiophoresis has also been experimentally demonstrated, [49,50] and seems especially attractive in a nanopore-based DNA sequencing method, which is called the third-generation DNA sequencing, with cost sufficiently low to revolutionize genomic medicine. [51][52][53] However, compared to the extensively studied electrophoresis for micro/nanofluidic applications, the existing study on diffusiophoresis is relatively limited, and is subjected to several restrictions, such as thin EDL, low zeta potential or surface charge on the particle, and only marginally non-uniform solute concentration.…”

Influence of double-layer polarization and chemiosmosis on the diffusiophoresis of a non-spherical polyelectrolyte

“…Due to its potential applications in several areas of practical significance, such as separation and purification [1][2][3][4][5], surface adhesion, coating [6][7][8][9], and pattern formation [10,11], diffusiophoresis was studied by many researchers. Recent applications such as catalytic nano-or micromo- tors [12][13][14] and nano-scaled sensing devices [15,16] also involve diffusiophoresis. Chemotaxis, the migration of cells and microorganisms driven by a concentration gradient of chemicals such as nutrients and toxic species, is also related to diffusiophoresis.…”

Electrophoretic motion of a nanorod along the axis of a nanopore under a salt gradient

“…Diffusiophoresis has also been analyzed for additionally controlling the electrophoretic motion of a spherical nanoparticle in a nanopore [50][51][52]. Regulation of DNA nanoparticle electrophoresis through a nanopore by the diffusiophoresis has been experimentally demonstrated [56,57].…”

“…More rigorous studies on the diffusiophoresis are performed by the authors for a spherical nanoparticle [50][51][52]. In order to mimic stretched DNAs translocating in a nanopore [61], our theoretical study was extended to an elongated cylindrical nanoparticle [55].…”