Vakourov, A, Galluzzi, M, Podesta, A et al. (3 more authors) (2014) Direct characterisation of fluid lipid assemblies on mercury in electric fields. ACS Nano, 8 (4). pp. 3242-3250. ISSN 1936-0851
Abstract
Phospholipid monolayers on mercury (Hg) surfaces have received substantial and extensive scientific interest not only because of their use as a biomembrane model but also for their application as a successful toxicity-sensing element. The monolayers show characteristic and very reproducible phase transitions manifest as consecutive voltammetric peaks in response to applied transverse electric fields. Unfortunately, apart from the results of simulation studies, there is a lack of data on the lipid phase structures to help interpret these voltammetric peaks. In this paper we report on the direct measurement of the structural changes underlying the phase transitions of phospholipid layers of dioleoyl phosphatidylcholine (DOPC) at electrified Hg surfaces using atomic force microscopy force–distance techniques. These direct measurements enable a description of the following structural changes in fluid lipid assemblies on a liquid electrode within an increasing transverse electric field. At about −1.0 V (vs Ag/AgCl) a field-facilitated ingress of ions and water into the monolayer results in a phase transition to a structured 2D emulsion. This is followed by a further phase transition at more negative potentials involving the readsorption of bilayer patches. At stronger values of field the bilayer patches form semivesicles, which subsequently collapse to form a monolayer of uncertain composition at very negative potentials. The observation that a monolayer on Hg converts to a bilayer by increasing the applied potential has allowed techniques to be developed for preparing and characterizing a near-continuous DOPC bilayer on Hg in an applied potential window within −1.0 and −1.4 V (vs Ag/AgCl).
Metadata
Item Type: | Article |
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Authors/Creators: |
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Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Biomedical Sciences (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemistry (Leeds) > Physical Chemistry (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Molecular & Nanoscale Physics |
Funding Information: | Funder Grant number EPSRC EP/G015325/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 22 Mar 2017 16:02 |
Last Modified: | 14 May 2019 11:58 |
Status: | Published |
Publisher: | American Chemical Society |
Identification Number: | 10.1021/nn4037267 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:101184 |