Lipid Bilayer thickness measured by quantitative DIC reveals phase transitions and effects of substrate hydrophilicity

Regan, David ORCID: https://orcid.org/0000-0003-0420-3481, Williams, Joseph, Borri, Paola ORCID: https://orcid.org/0000-0002-7873-3314 and Langbein, Wolfgang ORCID: https://orcid.org/0000-0001-9786-1023 2019. Lipid Bilayer thickness measured by quantitative DIC reveals phase transitions and effects of substrate hydrophilicity. Langmuir 35 (43) , pp. 13805-13814. 10.1021/acs.langmuir.9b02538

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Abstract

Quantitative differential interference contrast microscopy is demonstrated here as a label-free method, which is able to image and measure the thickness of lipid bilayers with 0.1 nm precision. We investigate the influence of the substrate on the thickness of fluid-phase 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)-supported lipid bilayers and find a thinning of up to 10%, depending on substrate hydrophilicity, local bilayer coverage, and ionic strength of the medium. With fluorescently labeled lipid bilayers, we also observe changes in the bilayer thickness depending on the choice of fluorophore. Furthermore, liquid-ordered domains in bilayers, formed from DOPC, cholesterol, and sphingomyelin, are measured, and the corresponding thickness change between the liquid-ordered and liquid-disordered phases is accurately determined. Again, the thickness difference is found to be dependent on the presence of the fluorophore label, highlighting the need for quantitative label-free techniques.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy Biosciences
Publisher:	American Chemical Society
ISSN:	0743-7463
Funders:	EPSRC
Date of First Compliant Deposit:	12 November 2019
Date of Acceptance:	4 September 2019
Last Modified:	03 Apr 2024 01:07
URI:	https://orca.cardiff.ac.uk/id/eprint/126735

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