| Summary: | 碩士 === 嘉南藥理科技大學 === 化妝品科技研究所 === 100 === Hydrogenated lecithin (HL) is used as a major component to form liposomes. Cholesterol (chol) and stearyl alcohol (C16OH), cetyl alcohol (C18OH), and sodium deoxycholate monohydrate (NaDC) are incorporated into HL liposomes to improve liposome stability. In this study, particle size analyzer, fluorescence polarization instrument, and differential scanning calormetry (DSC) are used to examine physicochemical properties of liposomes. After evaluation of physical stability of liposomes, the optimum liposome formulation was used to encapsulate ascorbic acid palmitate and encapsulation efficiency was determined by high pressure liquid chromatography (HPLC). Surface pressure-area per molecule (π-A) isotherms of mixed HL/Cholesterol, HL/NaDC, HL/C16OH, and HL/C18OH monolayers at the air/liquid interface were measured by a Langmuir trough technique and a fluorescence microscope was to observe the monolayer morphology.
Pure HL liposomes could be stable storaged at room temperature about 500 days. Adding cholesterol, NaDC, C16OH, and C18OH into HL liposomes could not improve storage stability. Adding cholesterol, NaDC, C16OH, and C18OH into HL liposomes could increase membrane fluidity then decrease. DSC results indicated that adding cholesterol, NaDC, C16OH, and C18OH into HL liposomes could reduce the enthalpy of bilayer phase transition. HL liposomes were capable of higher ascorbyl palmitate loading. Encapsulation of ascorbyl palmitate in HL/NaDC liposome showed greater stability. HL liposomes with NaDC have lower membrane fluidity than the other mixed system, resulting in well protecting of ascorbyl palmitate againest degradation.
This study also used the Franz diffusion cell to investigate the penetration behavior of mixed HL/Chol, HL/NaDC, HL/C16OH and HL/C18OH (molar ratio of 8/2) liposomes through nylon membranes with different pore size. The results indicated that liposome could penetrate through the membranes with a pore size of 200 nm, but only HL/NaDC and HL/C18OH liposomes could penetrate through the membrane with a pore size of 100 nm.
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