Influence of the Lipid Backbone on Electrochemical Phase Behavior

Philip N. Jemmett, David C. Milan, Richard J. Nichols, Thomas Howitt, Alexandra L. Martin, Thomas Arnold, Jonathan L. Rawle, Christopher L. Nicklin, Timothy R. Dafforn, Liam R. Cox, Sarah L. Horswell

Research output: Contribution to journalArticlepeer-review

1 Citation (SciVal)


Sphingolipids are an important class of lipids found in mammalian cell membranes with important structural and signaling roles. They differ from another major group of lipids, the glycerophospholipids, in the connection of their hydrocarbon chains to their headgroups. In this study, a combination of electrochemical and structural methods has been used to elucidate the effect of this difference on sphingolipid behavior in an applied electric field. N-Palmitoyl sphingomyelin forms bilayers of similar coverage and thickness to its close analogue di-palmitoyl phosphatidylcholine. Grazing incidence diffraction data show slightly closer packing and a smaller chain tilt angle from the surface normal. Electrochemical IR results at low charge density show that the difference in tilt angle is retained on deposition to form bilayers. The bilayers respond differently to increasing electric field strength: chain tilt angles increase for both molecules, but sphingomyelin chains remain tilted as field strength is further increased. This behavior is correlated with disruption of the hydrogen-bonding network of small groups of sphingomyelin molecules, which may have significance for the behavior of molecules in lipid rafts in the presence of strong fields induced by ion gradients or asymmetric distribution of charged lipids.

Original languageEnglish
Pages (from-to)14290-14301
Number of pages12
Issue number46
Early online date10 Nov 2022
Publication statusPublished - 22 Nov 2022
Externally publishedYes

Bibliographical note

Funding Information:
P.N.J., A.L.M., and T.H. thank the University of Birmingham and the BBSRC-funded Midlands Integrative Biosciences Training Partnerships (grant numbers BB/J014532/1 [P.N.J.], BB/M01116X/1 [A.L.M.] and BB/T00746X/1 [T.H.]) for studentships. The authors are grateful to Dr. V. Zamlynny and Prof. J. Lipkowski for kindly allowing us to use the Fresnel software and to Dr. A. L. N. Pinheiro for the electrochemical data acquisition software. The technical support of Mr. A. Rothin, Mr. S. Williams, and Mr. S. G. Arkless is gratefully acknowledged. The GIXD and XRR measurements were supported by Diamond Light Source and the Birmingham-Diamond collaboration (experiments SI-15539 and SI-18202).

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


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