Jurkiewicz Piotr, Olzyńska Agnieszka, Langner Marek, Hof Martin
J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-18223 Prague 8, Czech Republic.
Langmuir. 2006 Oct 10;22(21):8741-9. doi: 10.1021/la061597k.
The biophysical properties of liposome surfaces are critical for interactions between lipid aggregates and macromolecules. Liposomes formed from cationic lipids, commonly used to deliver genes into cells in vitro and in vivo, are an example of such a system. We apply the fluorescence solvent relaxation technique to study the structure and dynamics of fully hydrated liquid crystalline lipid bilayers composed of mixtures of cationic dioleoyltrimethylammoniumpropane (DOTAP) and neutral dioleoylphosphatidylcholine (DOPC). Using three different naphthalene derivatives as fluorescent dyes (Patman, Laurdan and Prodan) allowed different parts of the headgroup region to be probed. Wavelength-dependent parallax quenching measurements resulted in the precise determination of Laurdan and Patman locations within the DOPC bilayer. Acrylamide quenching experiments were used to examine DOTAP-induced dye relocalization. The nonmonotonic dependence of dipolar relaxation kinetics (occurring exclusively on the nanosecond time scale) on DOTAP content in the membrane was found to exhibit a maximum mean solvent relaxation time at 30 mol % of DOTAP. Up to 30 mol %, addition of DOTAP does not influence the amount of bound water at the level of the sn(1) carbonyls, but leads to an increased packing of phospholipid headgroups. Above this concentration, elevated lipid bilayer water penetration was observed.
脂质体表面的生物物理性质对于脂质聚集体与大分子之间的相互作用至关重要。由阳离子脂质形成的脂质体常用于在体外和体内将基因传递到细胞中，就是这样一个系统的例子。我们应用荧光溶剂弛豫技术来研究由阳离子二油酰基三甲基铵丙烷（DOTAP）和中性二油酰基磷脂酰胆碱（DOPC）混合物组成的完全水合液晶脂质双层的结构和动力学。使用三种不同的萘衍生物作为荧光染料（Patman、Laurdan和Prodan）可以探测头基区域的不同部分。波长依赖性视差猝灭测量结果精确确定了Laurdan和Patman在DOPC双层中的位置。丙烯酰胺猝灭实验用于研究DOTAP诱导的染料重新定位。发现偶极弛豫动力学（仅在纳秒时间尺度上发生）对膜中DOTAP含量的非单调依赖性在DOTAP含量为30摩尔%时表现出最大平均溶剂弛豫时间。在高达30摩尔%时，添加DOTAP不会影响sn(1)羰基水平上的结合水量，但会导致磷脂头基的堆积增加。高于此浓度时，观察到脂质双层水渗透率升高。
