Characterization of mixed DODAB/monoolein aggregates using Nile Red as a solvatochromic and anisotropy fluorescent probe

The aim of this study was to get a further knowledge of the interactions between lamellar and non-lamellar forming-phospholipids, as a tool to better understand the membrane dynamics and function. We have studied the behavior of aqueous mixtures of a cationic lipid (dioctadecyldimethylammonium bromide) and a neutral phospholipid (1-monoolein) in 10–150 μM total lipid concentration range. The effect of 1-monoolein on the physical properties (microviscosity, hydration and polarity) of the self-organized mixed aggregates was accessed by studying the steady-state fluorescence emission and anisotropy of the dye Nile Red. This information was combined with 90° Static Light Scattering assays in order to detect any structural variations in these vesicle systems. The results were interpreted by the coexistence of vesicular structures and other aggregates probably with a bicontinuous nature.