DNA-Based Optical Quantification of Ion Transport across Giant Vesicles

Marcus Fletcher, Jinbo Zhu, Roger Rubio-Sánchez, Sarah E. Sandler, Kareem Al Nahas, Lorenzo Di Michele, Ulrich F. Keyser, Ran Tivony

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Accurate measurements of ion permeability through cellular membranes remains challenging due to the lack of suitable ion-selective probes. Here we use giant unilamellar vesicles (GUVs) as membrane models for the direct visualization of mass translocation at the single-vesicle level. Ion transport is indicated with a fluorescently adjustable DNA-based sensor that accurately detects sub-millimolar variations in K+concentration. In combination with microfluidics, we employed our DNA-based K+sensor for extraction of the permeation coefficient of potassium ions. We measured K+permeability coefficients at least 1 order of magnitude larger than previously reported values from bulk experiments and show that permeation rates across the lipid bilayer increase in the presence of octanol. In addition, an analysis of the K+flux in different concentration gradients allows us to estimate the complementary H+flux that dissipates the charge imbalance across the GUV membrane. Subsequently, we show that our sensor can quantify the K+transport across prototypical cation-selective ion channels, gramicidin A and OmpF, revealing their relative H+/K+selectivity.

Original languageEnglish
Pages (from-to)17128-17138
Number of pages11
JournalACS Nano
Volume16
Issue number10
DOIs
StatePublished - 25 Oct 2022
Externally publishedYes

Keywords

  • G-quadruplex
  • giant unilamellar vesicles
  • ion channels
  • ion sensor
  • ion transport
  • microfluidics

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy

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