How does a small change in the structure of a phospholipid affect its
supramolecular assembly? In aqueous suspensions, the substitution of one
ester linkage in DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) by
an ether linkage alters its phase behaviour completely. To unravel the
effect of replacing a phospholipid’s ester linkage by an ether linkage
in lipid monolayers, we characterized pure monolayers of the model lipid
DPPC and its sn-2 ether analogue PHPC
(1-palmitoyl-2-O-hexadecyl-sn-glycero-3-phosphocholine) as well as
mixtures of both by measurements of surface pressure – molecular area
(π–A_mol) isotherms. In addition, we used infrared reflection absorption
spectroscopy (IRRAS) and epifluorescence microscopy to study lipid condensation, lipid chain
orientation, headgroup hydration, and lipid miscibility in all samples.