2 research outputs found

    DNA Electrokinetic Translocation through a Nanopore: Local Permittivity Environment Effect

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    The effect of the local liquid permittivity surrounding the DNA nanoparticle, referred to as the local permittivity environment (LPE) effect, on its electrokinetic translocation through a nanopore is investigated for the first time using a continuum-based model, composed of the coupled Poisson–Nernst–Planck (PNP) equations for the ionic mass transport and the Stokes and Brinkman equations for the hydrodynamic fields in the region outside of the DNA and within the ion-penetrable layer of the DNA nanoparticle, respectively. The nanoparticle translocation velocity and the resulting current deviation are systematically investigated for both uniform and spatially varying permittivities surrounding the DNA nanoparticle under various conditions. The LPE effect in general reduces the particle translocation velocity. The LPE effect on the current deviation is insignificant when the imposed electric field is relatively high. However, when the electric field and the bulk electrolyte concentration are relatively low, both current blockade and enhancement are predicted with the LPE effect incorporated, while only current blockade is predicted with the assumption of constant liquid permittivity. It is thereby shown that regardless of the electric field imposed the predictions on ionic current with considering the LPE effect are in good qualitative agreement with the experimental observations obtained in the literature

    Controlling pH-Regulated Bionanoparticles Translocation through Nanopores with Polyelectrolyte Brushes

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    A novel polyelectrolyte (PE)-modified nanopore, comprising a solid-state nanopore functionalized by a nonregulated PE brush layer connecting two large reservoirs, is proposed to regulate the electrokinetic translocation of a soft nanoparticle (NP), comprising a rigid core covered by a pH-regulated, zwitterionic, soft layer, through it. The type of NP considered mimics bionanoparticles such as proteins and biomolecules. We find that a significant enrichment of H<sup>+</sup> occurs near the inlet of a charged solid-state nanopore, appreciably reducing the charge density of the NP as it approaches there, thereby lowering the NP translocation velocity and making it harder to thread the nanopore. This difficulty can be resolved by the proposed PE-modified nanopore, which raises effectively both the capture rate and the capture velocity of the soft NP and simultaneously reduces its translocation velocity through the nanopore so that both the sensing efficiency and the resolution are enhanced. The results gathered provide a conceptual framework for the interpretation of relevant experimental data and for the design of nanopore-based devices used in single biomolecules sensing and DNA sequencing
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