Exploration of neutral versus polyelectrolyte behavior of poly(ethylene glycol)s in alkali ion solutions using single-nanopore recording

Marie France Breton, Francoise Discala, Laurent Bacri, Damien Foster, Juan Pelta, Abdelghani Oukhaled

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

We examine the effect of alkali ions (Li+, Na+, K+, Rb+, Cs+) on the partitioning of neutral and flexible poly(ethylene glycol) into the alpha-hemolysin (α-HL) nanopore for a large range of applied voltages at high salt concentration. The neutral polymer behaves as if charged, that is, the event frequency increases with applied voltage, and the residence times decrease with the electric force for all cations except Li+. In contrast, in the presence of LiCl, we find the classical partitioning behavior of neutral polymers, that is, the event frequency and the residence times are independent of the applied voltage. Assuming that lithium does not associate with PEG enabled us to quantify the relative magnitude of the entropic and enthalpic contribution to the free- energy barrier and the number of complexed cations using two different arguments; the first estimate is based on the balance of forces, and the second is found comparing the blockade ratio in the presence of LiCl (no complexed ions) to the blockade ratio of chains in the presence of the other salts (with complexed ions). This estimate is in agreement with recent simulations. These findings demonstrate that the nanopore could prove useful for the rapid probing of the capabilities of different neutral molecules to form complexes with different ions.

Original languageEnglish
Pages (from-to)2202-2208
Number of pages7
JournalJournal of Physical Chemistry Letters
Volume4
Issue number13
Early online date20 Jun 2013
DOIs
Publication statusPublished - 3 Jul 2013
Externally publishedYes

Keywords

  • cation-PEG coordination
  • charged polymers
  • electro-osmosis
  • energy barrier
  • ion channel
  • transport

ASJC Scopus subject areas

  • Materials Science(all)

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