Binding of alkali metals to pore walls in nanopores modulates transmembrane ion current and ionic rectification [Abstract]

  • Rectifying nanopores feature ion currents that are higher for voltages of one polarity compared to the currents recorded for corresponding voltages of the opposite polarity. Rectification is important for many physiological functions e.g., transducing information along axons, and functioning of the heart. Synthetic pores with asymmetric current-voltage curves can function as switches for ions and charged molecules in solutions and could become building blocks for ionic circuits used in logic and sensory systems. Rectification of nanopores has been found to depend on the pore opening diameter, distribution of surface charges of the pore walls as well as pore geometry. Very little is however known on the dependence of ionic rectification on the type of transported ions. We performed experiments with single conically shaped nanopores in a polymer film, and recorded current-voltage curves in three electrolytes: LiCl, NaCl and KCl. Rectification degree of the pores, quantified as the ratioRectifying nanopores feature ion currents that are higher for voltages of one polarity compared to the currents recorded for corresponding voltages of the opposite polarity. Rectification is important for many physiological functions e.g., transducing information along axons, and functioning of the heart. Synthetic pores with asymmetric current-voltage curves can function as switches for ions and charged molecules in solutions and could become building blocks for ionic circuits used in logic and sensory systems. Rectification of nanopores has been found to depend on the pore opening diameter, distribution of surface charges of the pore walls as well as pore geometry. Very little is however known on the dependence of ionic rectification on the type of transported ions. We performed experiments with single conically shaped nanopores in a polymer film, and recorded current-voltage curves in three electrolytes: LiCl, NaCl and KCl. Rectification degree of the pores, quantified as the ratio of currents recorded for voltages of opposite polarities, was the highest for KCl, and the lowest for LiCl. The currents recorded in LiCl as the bulk electrolyte were also several times lower than predicted from relative bulk conductivities of KCl and LiCl. The experimental observations could not be explained by a continuum modeling based on the Poisson-Nernst-Planck equations. All-atom molecular dynamics simulations revealed differential binding between Li+, Na+, and K+ ions and carboxylate residues on the pore wall, resulting in changes to both the effective surface charge of the nanopore and cation mobility within the pore. Differences in ionic current rectification follows from these factors.show moreshow less

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Metadaten
Author:Trevor P. Gamble, Jan-Frederik PietschmannORCiDGND, Karl Decker, Aleksei Aksimentiev, Zuzanna Siwy
Frontdoor URLhttps://opus.bibliothek.uni-augsburg.de/opus4/102083
ISSN:0006-3495OPAC
Parent Title (English):Biophysical Journal
Publisher:Elsevier BV
Place of publication:Amsterdam
Type:Article
Language:English
Year of first Publication:2014
Release Date:2023/02/20
Tag:Biophysics
Volume:106
Issue:Issue 2, Supplement 1
First Page:215a
DOI:https://doi.org/10.1016/j.bpj.2013.11.1260
Institutes:Mathematisch-Naturwissenschaftlich-Technische Fakultät
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Mathematik
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Mathematik / Lehrstuhl für Inverse Probleme