Sponsor
The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC-Advanced Grant Project 321172 PANDORA.
Published In
ACS Nano
Document Type
Article
Publication Date
11-2017
Subjects
Membranes (Biology), Active biological transport, Nanoparticles, Gold, Membrane potentials (Electrophysiology), Fluorescence spectroscopy, Electrochemistry
Abstract
Carborane-capped gold nanoparticles (Au/carborane NPs, 2–3 nm) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning. Such changes can be made either with a potentiostat in an electrochemical cell or by competition with another partitioning ion, for example, potassium in the presence of its specific transporter valinomycin. Carborane-capped gold nanoparticles have a ligand shell full of voids, which stem from the packing of near spherical ligands on a near spherical metal core. These voids are normally filled with sodium or potassium ions, and the charge is overcompensated by excess electrons in the metal core. The anionic particles are therefore able to take up and release a certain payload of cations and to adjust their net charge accordingly. It is demonstrated by potential-dependent fluorescence spectroscopy that polarized phospholipid membranes of vesicles can be depolarized by ion transport mediated by the particles. It is also shown that the particles act as alkali-ion-specific transporters across free-standing membranes under potentiostatic control. Magnesium ions are not transported.
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DOI
10.1021/acsnano.7b06600
Persistent Identifier
http://archives.pdx.edu/ds/psu/23719
Citation Details
Grzelczak, M. P., Danks, S. P., Klipp, R. C., Belic, D., Zaulet, A., Kunstmann-Olsen, C., & ... Brust, M. (2017). Ion Transport across Biological Membranes by Carborane-Capped Gold Nanoparticles. ACS Nano, 11(12), 12492-12499.
Description
This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
© 2017 American Chemical Society.