(The) structures and stabilities of liposome incorporated with ganglioside G(M1)

Abstract

The thermotropic behavior and vesicle fusion of aqueous dispersions of L-α-dipalmitoylphosphatidylcholine (DPPC)-Ganglioside G(M1) mixtures have been determined by High sensitivity differential scanning calorimeter and spectrophotometer. For the mixtures of pure DPPC and Cholesterol, and 0.24, 0.30, 0.50 and 0.68 mole fraction of G(M1) in DPPC, the phase transition temperatures on the thermogram continueously shifted between 32.6 and 47.2℃ depending on the G(M1) mole fraction. The incorporation of Ganglioside in film occurred up to a ganglioside mole fraction of about 0.25 to 0.3, at which point a marked physical change occurs. The fusion rates of SUV were little affected by the incorporation of the ganglioside G(M1) but were highly depressed by the incorporation of cholesterol and G(M1). Finally, the flocculation equation with Smoluchowski fast flocculation was derived and appropriate for determining the number of dispersed vesicles per unit volume and the rate of vesicle fusion. The transmittance of mixed DPPC vesicles varied linearly with the reciprocal fourth power of the wavelength in the range of 750 to 400nm at only X(G)=0.0 to 0.24, while above the concentration, they curved, indicating different shapes from spherical liposome.