| 摘要: | 本研究主要使用氫化大豆卵磷脂(hydrogenated lecithin, HL )以薄膜水合法製備出微脂粒，添加膽固醇(cholesterol)、膽鹽(sodium deoxycholate monohydrate)、十六碳醇(cetyl alcohol)以及十八碳醇(stearyl alcohol)等材料期望可增加微脂粒之物理穩定性，使用雷射粒徑暨界面電位分析儀，量測粒徑及界面電位分佈、穿透式電子顯微鏡(transmission electron microscope, TEM)觀察微脂粒之外觀、微分掃描熱卡計(different scanning calorimeter, DSC)觀察微脂粒之相轉移溫度、多功能光譜分析儀量測螢光偏極化，藉此了解上述添加物對 HL 微脂粒之效應，再者利用高效能液相層析儀測量微脂粒對於維他命C棕櫚酸酯的包覆行為，與該樣品於室溫下儲存之穩定性。最後利用Langmuir trough了解微脂粒組成分子在氣/液界面上的行為，期望可以了解分子在親疏水界面的排列行為，並藉由螢光顯微鏡觀察混合單分子層之特徵。
實驗結果顯示單純HL形成微脂粒即具有良好之穩定性，可於室溫下穩定存放約500天，而添加膽固醇、膽鹽、十六碳醇及十八碳醇並無法有效增加微脂粒之儲存穩定性。由螢光偏極化之結果可以發現，添加少量膽鹽與膽固醇會使微脂粒之膜內排列變得較為緊密但添加大量之膽鹽與膽固醇則反而會擾亂HL微脂粒之排列行為，而添加十六碳醇與十八碳醇則會使HL微脂粒之排列變為較為鬆散，由DSC之結果可以發現HL微脂粒具有兩個相轉移溫度，添加膽鹽、膽固醇、十六碳醇、十八碳醇後會使相轉移溫度提高，並且使相轉移溫度變得較為均一，但熱焓量卻有下降的趨勢，因此推論熱焓量下降可能是添加物影響HL微脂粒變為較為不穩定之原因。不同系統之微脂粒對維他命C棕櫚酸酯皆有良好的包覆效率，但只有膽鹽系統可較有效地維持維他命C棕櫚酸酯之活性，對應螢光偏極化之結果發現，若載體之膜內流動性質較低可能有助於增加活性成分之穩定性。
本研究中進一步使用 Franz 擴散槽進行體外藥物穿透試驗，並使用不同孔徑大小之尼龍膜做為阻隔層，分別探討混合HL/膽固醇、HL/膽鹽、HL/十六碳醇及HL/十八碳醇(莫耳比8/2)微脂粒之體外穿透行為。結果顯示微脂粒皆可以順利通過200 nm 大小之孔洞，但只有HL/膽鹽 及HL/十八碳醇微脂粒可順利通過100 nm大小孔洞之尼龍膜。將體外穿透試驗結果比較粒徑分佈結果可發現膽鹽系統與十八碳醇系統具有較小的粒徑分佈，因此可以達到較好的穿透效率。
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. |
