本論文利用飽和脂質、未飽和脂質及固醇做人造細胞膜，以微胞電製法長出大約直徑5到200μm的GUVs (Giant Unilamellar Vesicles)，並使用C6-NBD-PC和NBD-DOPE做為螢光分子，利用螢光顯微鏡觀察GUVs隨溫度及成分所改變的表面形態。 結果顯示兩種成分所組成的細胞膜中，在相同溫度下，隨著飽和脂質比例增加，會增加細胞膜的液晶有序相(gel phase)，在相同的組成成分下，隨著溫度升高，會增加細胞膜的液晶無序相(liquid-disorder phase)，而且，無論是加入螢光分子C6-NBD-PC或NBD-DOPE，都會降低從膠相(gel phase)到液晶相(liquid crystalline phase)的相變溫度。然而，C6-NBD-PC的效應比NBD-DOPE的效應強，表示NBD位於sn-2鏈上比NBD位於脂質分子頭部所造成的效應更大。在三種成分所組成的細胞膜中，GUVs的表面形態會隨著固醇的加入後，和兩種成分所組成的細胞膜有所不同。最後，將會總結局部我們所觀察到的相圖。 We study the properties of GUVs (Giant Unilamellar Vesicles) model membranes composed of saturated lipid, unsaturated lipid and sterol. GUVs of 5 to 200μm in diameter were prepared by electroformation method. The morphology of GUVs were observed as a function of temperature and composition by fluorescence microscopy using C6-NBD-PC or NBD-DOPE as the fluorescent probe. The results for binary mixtures containing saturated and unsaturated lipids show that membranes become more ordered as the concentration of saturated lipid increases. For a given composition, the membranes become more disordered with increasing temperature. Moreover, the addition of fluorescent probe, C6-NBD-PC or NBD-DOPE, to GUVs lowers the temperature of the gel-to-liquid crystalline phase transition, as compared to those without fluorescent probe. However, C6-NBD-PC has stronger effect than NBD-DOPE, suggesting that fluorescent probe with NBD at the acyl chain disturbs the membrane structure more strongly than that at the headgroup. The morphology of GUVs of ternary mixtures differs from that of binary mixtures. A partial phase diagram summarize our findings will be presented.
