Langmuir, Vol.26, No.5, 3225-3231, 2010
Liposomes in Double-Emulsion Globules
Tubular liposomes containing a hydrophilic model compound (fluorescein sodium salt, FSS) were entrapped inside the internal aqueous phase (W-1) (W-1/O/W-2) double-emulsion globules. Our hypothesis was that the oil membrane of double emulsions can function as a layer of protection to liposomes and their contents and thus better control their release. Liposomes were prepared in bulk, and their release was observed microscopically from individual double-emulsion globules. The liposomes containing FSS were released through external coalescence, and the behavior of this system was monitored visually by capillary video microscopy. Double-emulsion globules were stabilized with Tween 80 its the water-soluble surfactant, with Span 80 as the oil-soluble surfactant, while the oil phase (O) was n-hexadecane. The lipids in the tubular liposomes consist of L-alpha-phosphatidylcholine and Ceramide-VI. Variations of Tween 80 Concentration in the external aqueous phase (W-2) and Span 80 concentration in the O phase controlled the release of liposomes front the W-1 phase to the W-2 phase. The major finding of this work is that the sheer presence of liposomes in the W-1 phase is by itself a stabilizing factor for double-emulsion globules.