Controlling pH-regulated bionanoparticles translocation through nanopores with polyelectrolyte brushes

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⁺ 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.