胆固醇对卵磷脂囊泡稳定性的影响

Effect of Cholesterol on the Stability of Lecithin Vesicle

采用透射电子显微镜研究了Gemini表面活性剂诱导卵磷脂囊泡结构改变的机理,用Langmuir膜天平研究卵磷脂和胆固醇的不溶单分子混合膜在气-液界面的行为和混合膜分子间的相互作用,并结合动态光散射技术和停留法探讨胆固醇对Gemini表面活性剂诱导卵磷脂囊泡结构改变的影响.从电镜结果可以推测带正电荷的Gemini表面活性剂分子会嵌入到带负电荷的卵磷脂囊泡双分子层的外层,囊泡的双分子层之间的相互吸引力使双分子层的厚度减少,由于嵌入的表面活性剂分子在囊泡的双分子层中分布是不均匀的,这种分布的不均匀性必然会导致双分子层厚度的不均匀,从而使囊泡破裂.混合膜的过剩面积和动力学结果表明,胆固醇和卵磷脂是相互吸引的,即胆固醇的加入使卵磷脂囊泡更不容易被表面活性剂破坏.

The mechanism of structure transformation of vesicle was explored through TEM. The mixed monolayer at the air/water interface of lecithin and cholesterol was investigated using Langmuir balance technique. We also studied the effect of cholesterol on the structure transformation of lecithin vesicle by the method of kinetic and dynamic light-scattering. The results show that positively charged Gemini surfactant intercalates into the bilayer of negatively charged lecithin vesicle and reduces the thickness of bilayer of lecithin vesicle. The asymmetric distributing of the surfactant molecular in the vesicle led to the asymmetric thickness of the bilayer, thus resulted in the vesicle breakdown. The excess area of the mixed monolayer and kinetic results show that the mutual attraction between lecithin and cholesterol made it hard to break the lecithin vesicle by adding cholesterol.