Electrostatic correlations on the ionic selectivity of cylindrical membrane nanopores

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© 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. http://scitation.aip.org/content/aip/journal/jcp

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Journal Title

Journal ISSN

Volume Title

School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2014

Major/Subject

Mcode

Degree programme

Language

en

Pages

067401

Series

The Journal of Chemical Physics, Volume 140, Number 6

Abstract

We characterize the role of electrostatic fluctuations on the charge selectivity of cylindrical nanopores confining electrolyte mixtures. To this end, we develop an extended one-loop theory that can account for correlation effects induced by the surface charge, nanoconfinement of the electrolyte, and interfacial polarization charges associated with the low permittivity membrane. We validate the quantitative accuracy of the theory by comparisons with previously obtained Monte-Carlo simulation data from the literature, and scrutinize in detail the underlying forces driving the ionic selectivity of the nanopore. In the biologically relevant case of electrolytes with divalent cations such as CaCl2 in negatively charged nanopores, electrostatic correlations associated with the dense counterion layer in the channel result in an increase of the pore coion density with the surface charge. This peculiarity analogous to the charge inversion phenomenon remains intact for dielectrically inhomogeneous pores, which indicates that the effect should be observable in nanofiltration membranes or DNA-blocked nanopores characterized by a low membrane permittivity. Our results show that a quantitatively accurate consideration of correlation effects is necessary to determine the ionic selectivity of nanopores in the presence of electrolytes with multivalent counterions.

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Keywords

surface charge, ionic liquid, polarization, nanoporous materials, electrostatic correlations

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Citation

Buyukdagli, Sahin & Ala-Nissilä, Tapio. 2014. Electrostatic correlations on the ionic selectivity of cylindrical membrane nanopores. The Journal of Chemical Physics. Volume 140, Number 6. 067401. 0021-9606 (printed). DOI: 10.1063/1.4864323.