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Effect of molecular structure on electrochemical phase behavior of phospholipid bilayers on Au(111)
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Jemmett, Philip N., Milan, David C., Nichols, Richard J., Cox, Liam R. and Horswell, Sarah L. (2021) Effect of molecular structure on electrochemical phase behavior of phospholipid bilayers on Au(111). Langmuir, 37 (40). pp. 11887-11899. doi:10.1021/acs.langmuir.1c01975 ISSN 0743-7463.
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Official URL: http://dx.doi.org/10.1021/acs.langmuir.1c01975
Abstract
Lipid bilayers form the basis of biological cell membranes, selective and responsive barriers vital to the function of the cell. The structure and function of the bilayer are controlled by interactions between the constituent molecules and so vary with the composition of the membrane. These interactions also influence how a membrane behaves in the presence of electric fields they frequently experience in nature. In this study, we characterize the electrochemical phase behavior of dipalmitoylphosphatidylcholine (DPPC), a glycerophospholipid prevalent in nature and often used in model systems and healthcare applications. DPPC bilayers were formed on Au(111) electrodes using Langmuir–Blodgett and Langmuir–Schaefer deposition and studied with electrochemical methods, atomic force microscopy (AFM) and in situ polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). The coverage of the substrate determined with AFM is in accord with that estimated from differential capacitance measurements, and the bilayer thickness is slightly higher than for bilayers of the similar but shorter-chained lipid, dimyristoylphosphatidylcholine (DMPC). DPPC bilayers exhibit similar electrochemical response to DMPC bilayers, but the organization of molecules differs, particularly at negative charge densities. Infrared spectra show that DPPC chains tilt as the charge density on the metal is increased in the negative direction, but, unlike in DMPC, the chains then return to their original tilt angle at the most negative potentials. The onset of the increase in the chain tilt angle coincides with a decrease in solvation around the ester carbonyl groups, and the conformation around the acyl chain linkage differs from that in DMPC. We interpret the differences in behavior between bilayers formed from these structurally similar lipids in terms of stronger dispersion forces between DPPC chains and conclude that relatively subtle changes in molecular structure may have a significant impact on a membrane’s response to its environment.
Item Type: | Journal Article | ||||||||
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Subjects: | Q Science > QH Natural history > QH301 Biology Q Science > QH Natural history > QH426 Genetics |
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Divisions: | Faculty of Science, Engineering and Medicine > Engineering > WMG (Formerly the Warwick Manufacturing Group) | ||||||||
Library of Congress Subject Headings (LCSH): | Bilayer lipid membranes, Liposomes, Molecular structure, Cell membranes | ||||||||
Journal or Publication Title: | Langmuir | ||||||||
Publisher: | American Chemical Society | ||||||||
ISSN: | 0743-7463 | ||||||||
Official Date: | 11 October 2021 | ||||||||
Dates: |
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Volume: | 37 | ||||||||
Number: | 40 | ||||||||
Page Range: | pp. 11887-11899 | ||||||||
DOI: | 10.1021/acs.langmuir.1c01975 | ||||||||
Status: | Peer Reviewed | ||||||||
Publication Status: | Published | ||||||||
Access rights to Published version: | Open Access (Creative Commons) | ||||||||
Date of first compliant deposit: | 18 August 2022 | ||||||||
Date of first compliant Open Access: | 18 August 2022 | ||||||||
Funder: | This work was supported by the BBSRC-funded Midlands Integrative Biosciences Training Partnership Centre for Doctoral Training (grant number BB/J014532/1) | ||||||||
RIOXX Funder/Project Grant: |
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