Molecular arrangements and interconnected bilayer formation induced by alcohol or polyalcohol in phospholipid vesicles

A self-assembled hybrid phospholipid vesicular system containing various penetration enhancers –ethanol, Transcutol and propylenglycol – was prepared and characterized. The effects of the differentalcohol or polyalcohols structure and their concentration on the features of the assembled vesicles wereevaluated using a combination of different techniques, including cryo-transmission electron microscopy,laser light scattering, differential scanning calorimetry, small- and wide-angle X-ray scattering and rheo-logical analysis. These techniques allow explaining the structural rearrangements of the bilayer assemblydue to the alcohol or polyalcohol addition. X-ray scattering studies showed that such addition at thehighest concentration (20%) allowed structure modification to oligolamellar vesicles and a bilayer tran-sition to interdigitated phase. Rheological studies confirmed the importance of alcohol or polyalcohol inthe structuring dispersions probably due to a partial tilting of phosphatidylcholine acyl chains forminginterdigitated and interconnected bilayer vesicles.