Effects of entrapped compounds and chemical structure and concentration of Brij on formation and characteristics of liposomes

The purposes of this study were to study the influence of chemical structure and concentration of Brij® on liposome formation and to investigate effect of entrapped compounds on formation and characteristic of liposomes. The results showed that, Brij® 30, Brij® 35 and Brij® 72 could be employed in preparation of liposomes using thin film hydration method. Blank liposomes (PC liposomes) and liposomes containing Brij® (PC-Brij® liposomes) were characterized for various parameters including vesicle shape and morphology, size and size distribution. The obtained PC-Brij® liposomes were characterized as multilamellar vesicles (MLVs) with smooth surface. Size differences of PC-Brij® liposomes were discussed on difference in physicochemical properties of Brij®. PC-Brij® liposomes composed of Brij® 30 at 20 % w/w of total lipid content (L_30/20) and PC-Brij® liposomes composed of Brij® 72 at 15 % w/w of total lipid content (L_72/15) were chosen for further study. Vesicle size reduction was observed from PC and PC-Brij® liposomes loaded with griseofulvin when compared to the corresponding blank PC and PC-Brij® liposomes. Percent griseofulvin entrapment efficiencies were related to vesicle size. Hydrophobicity of griseofulvin was expected to directly affect the bilayer characteristic. Griseofulvin was well retained inside the vesicles due to its hydrophobicity nature with approximately 20 % leakage after storage at 4 °C for 1 month. Sizes of PC and PC-Brij® liposomes loaded with hydrophilic carboxyfluorescein were comparable to the corresponding blank PC and PC-Brij® liposomes. % Carboxyfluorescein entrapment efficiencies were proportional to vesicle size. Leakage of carboxyfluorecein from all formulations was observed probably due to lyze and leak of vesicles.