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Modulation of electrophoresis, electroosmosis and diffusion for electrical transport of proteins through a solid-state nanopore.

ABSTRACT: Nanopore probing of molecular level transport of proteins is strongly influenced by electrolyte type, concentration, and solution pH. As a result, electrolyte chemistry and applied voltage are critical for protein transport and impact, for example, capture rate (C _R), transport mechanism (i.e., electrophoresis, electroosmosis or diffusion), and 3D conformation (e.g., chaotropic vs. kosmotropic effects). In this study, we explored these using 0.5-4 M LiCl and KCl electrolytes with holo-human serum transferrin (hSTf) protein as the model protein in both low (±50 mV) and high (±400 mV) electric field regimes. Unlike in KCl, where events were purely electrophoretic, the transport in LiCl transitioned from electrophoretic to electroosmotic with decreasing salt concentration while intermediate concentrations (i.e., 2 M and 2.5 M) were influenced by diffusion. Segregating diffusion-limited capture rate (R _diff) into electrophoretic (R _diff,EP) and electroosmotic (R _diff,EO) components provided an approach to calculate the zeta-potential of hSTf (ζ _hSTf) with the aid of C _R and zeta potential of the nanopore surface (ζ _pore) with (ζ _pore-ζ _hSTf) governing the transport mechanism. Scrutinization of the conventional excluded volume model revealed its shortcomings in capturing surface contributions and a new model was then developed to fit the translocation characteristics of proteins.

SUBMITTER: Saharia J

PROVIDER: S-EPMC8285365 | biostudies-literature |

REPOSITORIES: biostudies-literature

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