Rao Zhi, Taguchi Tetsushi
Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Colloids Surf B Biointerfaces. 2012 Sep 1;97:248-53. doi: 10.1016/j.colsurfb.2012.03.017. Epub 2012 Apr 3.
In order to confirm that the cholesterol end groups of cholesterol-end capped polyethylene glycol really insert into the liposome bilayer and investigate how the incorporation affects the microenvironment of liposome bilayer, two kinds of molecular probes, namely Nile Red and pinacyanol chloride, were used. Their UV-visible and fluorescence spectrum were recorded before and after the addition of the polymer. Shifts of the maximum absorbance (λ(max)) of Nile Red show that the bilayer microenvironment around Nile Red is becoming more polar with increasing polymer concentration while shifts of λ(max) of pinacyanol chloride indicate that the surrounding environment of pinacyanol chloride is becoming more apolar with addition of polymer. Effect of composition of liposome was also studied. With high ratio of dimethyldioctadecylammonium bromide (DODAB) fraction in liposome, λ(max) of Nile Red is more easily affected by the addition of Chol-PEG-Chol while liposome with cholesterol shows relatively high stability to the addition of Chol-PEG-Chol.
为了证实胆固醇封端的聚乙二醇的胆固醇端基确实插入脂质体双层膜中，并研究这种掺入如何影响脂质体双层膜的微环境，使用了两种分子探针，即尼罗红和氯化吡那醇。在添加聚合物之前和之后记录了它们的紫外可见光谱和荧光光谱。尼罗红最大吸收波长（λ(max)）的位移表明，随着聚合物浓度的增加，尼罗红周围的双层微环境变得更加极性，而氯化吡那醇的λ(max)位移表明，添加聚合物后氯化吡那醇的周围环境变得更加非极性。还研究了脂质体组成的影响。当脂质体中溴化二甲基二十八烷基铵（DODAB）比例较高时，尼罗红的λ(max)更容易受到胆固醇-聚乙二醇-胆固醇添加的影响，而含有胆固醇的脂质体对胆固醇-聚乙二醇-胆固醇的添加显示出相对较高的稳定性。
