微脂粒一般是磷脂質所組成，其材料與結構相似於細胞膜，因此 具有生物相客性、低毒性與多功能性的特色，目前已被廣泛被使用於藥 品、食品與化妝品劑型。基於成本之考量，本文使用氫化大豆卵磷脂 (hydrogenated lecithin, HL)做為製備微脂粒之材料，根據先前學者文獻中 指出磷脂質之組成與微脂粒的物理穩定性息息相關，因此了解膽固醇於 微脂粒之膜内所扮演的角色，實為重要。最後並探討膽固醇於包覆維他 命C棕櫚酸酯微脂粒的影響。為了進ー步了解氫化大豆卵磷脂(HL)微脂 粒之物理化學特性，本實驗中利用雷射粒徑分析儀、穿透式電子顯微鏡 (transmission electron microscope, TEM)、微分掃描熱卡計（dferent scanning calorimeter, DSC)、及多功能光譜分析儀等儀器，分別觀察HL 微脂粒之粒徑、界面電位、樣品外觀、相變化行為、雙層膜内分子排列 之流動性，最後並應用高效能液相層析儀分析HL微脂粒包覆維他命C 棕櫚酸酯之效率。實驗結果發現HL微脂粒為球型結構，具有良好之穩定 性，其穩定天數可長達400多天，添加膽固醇於HL微脂粒中，隨膽固醇 濃度增加會使其於室溫下之脂雙層膜内之流動性有先下降後上升之趨勢，
而相轉移溫度之熱焓隨著膽固醇添加量的增加而有變小之趨勢，藉由高 效能液相層析儀可以觀察到HL/膽固醇微脂粒系統具有高達90~98%之維 他命C棕櫚酸酯包覆效率。

Liposomes consisted of membrane-like phospholipid bilayers surrounding by an aqueous medium. It was widely reported that liposome have been used in delivery of active compounds into the skin. Hydrogenated lecithin (HL) contains 70% hydrogenated phosphatidyl choline and 30% phosphatidyl ethanolamine. HL is used as a major component to form liposomes under economic consideration. However, HL liposomes are not stable enough, and we tried incorporation of cholesterol into HL liposomes to improve this defect. 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 encapsulated ascorbic acid palmitate and encapsulation efficiency was determined by high pressure liquid chromatography (HPLC). The HL liposomes added with cholesterol showed average particle size range of about 76-150 nm. Pure HL liposomes could be stable stored at room temperature for about 500 days. Adding cholesterol into HL liposomes could not improve storage stability. With increasing concentration of cholesterol in HL liposomes, the evidence of a phase transition was eliminated and the enthalpy of phase transition was reduced to zero at 50 mol% cholesterol (1:1 ratio).