Effect of Deep Eutectic Solvent Nanostructure on Phospholipid Bilayer Phases

Abstract

Phospholipids are shown by solvent penetration experiments to form lamellar phases and sponta-neously spawn vesicles in a wide range of deep eutectic solvents (DESs) composed of alkylammoni-um halide salts and glycerol or ethylene glycol, which are shown to be nanostructured by X-ray scat-tering. In contrast with molecular solvents, the chain melting temperature of each phospholipid, which determines the stability of the swellable bilayer phase, depends on the structure of the cation, anion and molecular H-bond donor that constitute the DES. Chain melting is most sensitive to the length of the alkyl chain of the cation, which is partitioned between apolar domains in the bulk, nanostructured DES and those within the lipid bilayer. This is moderated by the structures of the an-ion and the molecular hydrogen bond donor, which determine the extent of polar/apolar segregation in the bulk liquid.