| 摘要: | 在本研究中，探討氫化大豆磷脂質(hydrogenated soybean phosphatidylcholine, HSPC)及卵磷脂(egg phosphatidylcholine, EPC)兩種飽和度不同之磷脂質(phosphatidylcholine, PC)添加雙十八烷基二甲基溴化銨(dioctadecyldimethylammonium bromide, DODAB)所形成液胞之物化特徵。藉由量測液胞粒徑和界面電位以觀察其在室溫下的穩定性。使用螢光偏極化技術分析液胞添加DODAB對於脂雙層結構分子排列的影響。並使用微分掃描熱卡計探討液胞分散液的相轉變行為。經由穿透式電子顯微鏡(Transmission electron microscope,TEM)觀察液胞的微結構。再者，藉由Langmuir trough 技術，進行在氣/液界面上混合HSPC/DODAB及EPC/DODAB單分子層表面壓-每分子占據面積 (-A)等溫線的量測，以及進行在固定表面壓30mN/m下單分子層面積鬆弛實驗，以了解混合雙成分分子間的交互作用。最後選擇穩定的奈米級液胞配方包覆熊果素(arbutin)並進行體外經皮吸收試驗。
在純水中添加DODAB於HSPC和EPC液胞中可以提升液胞的穩定性，減少粒徑，降低粒徑分佈，及使液胞表面帶正電荷。DODAB的添加對HSPC液胞脂雙層流動性無明顯改變，主要相變溫度隨DODAB莫耳分率增加呈現先上升後下降的現象，但添加DODAB會使EPC液胞脂雙層膜內流動性降低及主要相轉變溫度上升。不同濃度(2 mM和20 mM及200 mM)磷酸鹽緩衝溶液會降低HSPC/DODAB液胞的穩定性。分散在2 mM磷酸鹽緩衝溶液 EPC/DODAB混合液胞穩定性比分散在20 mM及200 mM磷酸鹽緩衝溶液EPC/DODAB混合液胞較好。混合單分子層-A等溫線的結果顯示HSPC/DODAB 和EPC/DODAB在氣/液界面是相互混合的。從固定壓表面下面積鬆弛實驗發現HSPC/DODAB 5/5 和7/3混合單分子層會呈現具較佳之動態穩定性。此外，在熊果素的存在下，HSPC/DODAB液胞脂雙層膜的流動性會增加，EPC/DODAB液胞脂雙層膜的流動性會降低。PC/DODAB液胞包覆熊果素之包覆效率隨DODAB所佔比例增高而下降。
Physicochemical properties of vesicles composed of phosphatidylcholines with different saturated degree, namely hydrogenated soybean phosphatidylcholine (HSPC) and egg phosphatidylcholine (EPC), adding with dioctadecyldimethylammonium bromide (DODAB) are investigated. The vesicles were characterized by means of determination of size distribution, zeta-potential analysis, and the storage stability. Mixed HSPC/DODAB and mixed EPC/DODAB cationic vesicles carried out fluorescence polarization examination to study effect of DODAB on molecular arrangement of the lipid bilayer. Differential scanning calorimetry (DSC) was used to investigate the phase transition behavior of vesicles. Transmission electron microscope (TEM) has been used for observation of vesicles structure directly. Furthermore, surface pressure – per molecular area (-A) isotherms of mixed HSPC/DODAB and EPC/DODAB monolayers at the air/water interface and area relaxation curves fixed at a surface pressure of 30 mN/m were measured at 24℃ to understand molecular interaction between PC and DODAB. Finally, a reliable vesicles formulation was selected to arbutin and in vitro skin penetration efficiency of vesicles-arbutin was evaluated.
Adding DODAB into HSPC and EPC vesicles increased storage stability, decreased of particle size and size distribution, and showed positive zeta potential. Adding DODAB into HSPC vesicles does not changes membrane bilayer fluidity, and the main transition temperature of vesicles was increased as XDODAB from 0 to 0.5, and then decreased as XDODAB >0.5. But incorporation of DODAB into EPC vesicles increased main transition temperature and decreased the membrane bilayer fluidity. Mixed HSPC/DODAB vesicles dispersed in different concentrations (2 mM, 20 mM and 200 mM) of phosphate buffer saline is unstable. The stability of mixed EPC/DODAB vesicles dispersed in 2 mM phosphate buffer was better than that in 20 mM and 200 mM phosphate buffers. The -A isotherms indicate that HSPC/DODAB and EPC/DODAB monolayers were miscible respectively at the air/water interface. Area relaxation curves fixed at 30 mN/m expressed that HSPC/DODAB 5/5 and 7/3 monolayers showed more stable kinetically. In the presence of arbutin, membrane bilayer fluidity of HSPC/DODAB vesicles was increased, but that of EPC/DODAB vesicles was decreased. The entrapment efficiency of PC/DODAB vesicles encapsulating with arbutin decreased as molar ratio of DODAB increased. |
