The effect of 3-pentadecylphenol on DPPC bilayers ATR-IR and 31P NMR studies

The influence of 3-pentadecylphenol (PDP) on the structure and physicochemical properties of the lipid bilayers of DPPC liposomes was studied using ATR-IR and 31P NMR methods. On the basis of analysis of the bands assigned to the CH2 stretching, CH2 scissoring, CO stretching, and PO2− stretching vibrations it was revealed that PDP influences both the hydrophobic and hydrophilic parts of the DPPC liposome bilayer. Analysis of the 31P NMR line-shape indicated a lamellar to non-lamellar phase transition in PDP-doped DPPC dispersions. It was shown that PDP/DPPC isotropic aggregates have similar νCO and νasPO2− band positions and lower gauche populations in the hydrophobic chain region compared with the DPPC bilayer in the liquid-crystal phase.