Hungerford Graham, Castanheira Elisabete M S, Baptista Adelina L F, Coutinho Paulo J G, Oliveira M Elisabete C D Real
Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
J Fluoresc. 2005 Nov;15(6):835-40. doi: 10.1007/s10895-005-0014-3.
The effect of the cholesterol (Ch) on liposomes composed of the cationic lipid dioctadecyldimethylammonium bromide (DODAB) was assessed by studying both the steady-state and time-resolved fluorescence anisotropy of the dye Nile Red. The information obtained combined with analysis of the steady-state emission and fluorescence lifetime of Nile Red (NR) for different cholesterol concentrations (5-50%) elucidated the presence of "condensed complexes" and cholesterol-rich domains in these mixed systems. The steady-state fluorescence spectra were decomposed into the sum of two lognormal emissions, emanating from two different states, and the effect of temperature on the anisotropy decay of Nile Red for different cholesterol concentrations was observed. At room temperature, the time-resolved anisotropy decays are indicative of NR being relatively immobile (manifest by a high r (infinity) value). At higher temperature, rotational times ca. 1 ns were obtained throughout and a trend in increasing hindrance was seen with increase of Ch content.
通过研究染料尼罗红的稳态和时间分辨荧光各向异性，评估了胆固醇（Ch）对由阳离子脂质二辛基二甲基溴化铵（DODAB）组成的脂质体的影响。结合不同胆固醇浓度（5-50%）下尼罗红（NR）的稳态发射和荧光寿命分析所获得的信息，阐明了这些混合体系中“凝聚复合物”和富含胆固醇区域的存在。稳态荧光光谱被分解为源于两种不同状态的两个对数正态发射之和，并观察了温度对不同胆固醇浓度下尼罗红各向异性衰减的影响。在室温下，时间分辨各向异性衰减表明NR相对不移动（以高r(∞)值表现）。在较高温度下，整个过程中获得的旋转时间约为1 ns，并且随着Ch含量的增加，阻碍增加的趋势明显。
