Characteristic responses of a 1,2-dipalmitoleoyl-sn-glycero-3- phosphoethanolamine molecular layer depending on the number of CH(OH) groups in polyols

To elucidate the effect of polyols on a phospholipid molecular layer, different polyols with the formula H-(CH(OH))m-H (m = 2-6) were added to a phospholipid (1,2-dipalmitoleoyl-sn-glycero-3-phosphoethanolamine (DPoPE)) solution above and below the phase transition temperature between the lamellar and inverted hexagonal phases. As for the surface pressure (π)−surface area (A) isotherm of the phospholipid monolayer at the air-water interface, π at a constant value of A increased with increasing m, especially for xylitol (m = 5) and sorbitol (m = 6). Small angle X-ray scattering (SAXS) and Fourier transform IR spectrometry (FT-IR) were used to evaluate the interaction between DPoPE and the polyol molecules. The experimental results suggest that the number of CH(OH) groups in the polyol plays an important role in the characteristic interaction between DPoPE and the polyol in both the lamellar and inverted hexagonal phases.