Unusual phosphatidylcholine lipid phase behavior in the ionic liquid ethylammonium nitrate

Livia Salvati Manni, Caitlin Davies, Kathleen Wood, Salvatore Assenza, Rob Atkin, Gregory G. Warr

Research output: Contribution to journalArticleResearchpeer-review

4 Citations (Scopus)

Abstract

Hypothesis: The forces that govern lipid self-assembly ionic liquids are similar to water, but their different balance can result in unexpected behaviour. 

Experiments: The self-assembly behaviour and phase equilibria of two phospholipids, 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), in the most common protic ionic liquid, ethylammonium nitrate (EAN) have been investigated as function of composition and temperature by small- and wide-angle X-ray scattering (SAXS/WAXS) and small-angle neutron scattering (SANS). 

Findings: Both lipids form unusual self-assembly structures and show complex and unexpected phase behaviour unlike that seen in water; DSPC undergoes a gel Lβ to crystalline Lc phase transition on warming, while POPC forms worm-like micelles L1 upon dilution. This surprising phase behaviour is attributed to the large size of the EAN ions that solvate the lipid headgroup compared to water changing amphiphile packing. Weaker H-bonding between EAN and lipid headgroups also contributes. These results provide new insight for the design of lipid based nanostructured materials in ionic liquids with atypical properties.

Original languageEnglish
Pages (from-to)276-281
Number of pages6
JournalJournal of Colloid and Interface Science
Volume643
DOIs
Publication statusPublished - Aug 2023
Externally publishedYes

Keywords

  • Ionic liquids
  • LIPID self-assembly
  • Phospholipids
  • Small angle neutron scattering
  • Small angle X-ray scattering

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