Preparation of asymmetric bilayer-vesicles with inner and outer monolayerscomposed of different amphiphilic molecules

Asymmetric vesicles were prepared layer by layer from reverse micelles. The aqueous solution was first entrapped into reverse micelles prepared from l ipid, then these reverse micelles penetrated the monolayer formed by anothe r kind of amphiphilic agent at organic solvent/water interface by centrifug ation and were assembled spontaneously by the second layer to form asymmetr ic vesicles. In general, the diameters of the vesicles ranged from 30 to 10 0 nm. A fluorescein quenching experiment showed that asymmetric vesicles wi th the inner layer being lipid and the outer layer being single-chain amphi philic molecules, [(bpy)(2) Ru(diazafluorenone) (CH2)(15)CH3](PF6)(2), were successfully prepared. The half-life of flip-flop of the amphiphilic molec ules between inner and outer layers was estimated to be about 17 days. (C) 1998 Elsevier Science Limited. All rights reserved.