Sobral Cecília N C, Soto Marco A, Carmona-Ribeiro Ana M
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, P.O. Box 26077, 05513-970 São Paulo, SP, Brazil.
Chem Phys Lipids. 2008 Mar;152(1):38-45. doi: 10.1016/j.chemphyslip.2007.12.004. Epub 2008 Jan 12.
Dioctadecyldimethylammonium bromide (DODAB)/dipalmitoylphosphatidylcholine (DPPC) large and cationic vesicles obtained by vortexing a lipid film in aqueous solution and above the mean phase transition temperature (T(m)) are characterized by means of determination of phase behaviour, size distribution, zeta-potential analysis and colloid stability. The effect of increasing % DODAB over the 0-100% range was a nonmonotonic phase behaviour. At 50% DODAB, the mean phase transition temperature and the colloid stability were at maximum. There is an intimate relationship between stability of the bilayer structure and colloid stability. In 1, 50 and 150mM NaCl, the colloid stability for pure DPPC or pure DODAB vesicles was very low as observed by sedimentation or flocculation, respectively. In contrast, at 50% DODAB, remarkable colloid stability was achieved in 1, 50 or 150mM NaCl for the DODAB/DPPC composite vesicles. Vesicle size decreased but the zeta-potential remained constant with % DODAB, due to a decrease of counterion binding with vesicle size. This might be important for several biotechnological applications currently being attempted with cationic bilayer systems.
通过在水溶液中且高于平均相变温度（T(m)）下涡旋脂质膜获得的二辛基二甲基溴化铵（DODAB）/二棕榈酰磷脂酰胆碱（DPPC）大阳离子囊泡，通过测定相行为、尺寸分布、ζ电位分析和胶体稳定性来进行表征。在0 - 100%范围内增加DODAB的百分比所产生的影响是一种非单调的相行为。在DODAB含量为50%时，平均相变温度和胶体稳定性达到最大值。双层结构的稳定性与胶体稳定性之间存在密切关系。在1、50和150mM NaCl中，分别通过沉降或絮凝观察到，纯DPPC或纯DODAB囊泡的胶体稳定性非常低。相比之下，在DODAB/DPPC复合囊泡中，当DODAB含量为50%时，在1、50或150mM NaCl中可实现显著的胶体稳定性。随着DODAB百分比的增加，囊泡尺寸减小，但ζ电位保持不变，这是由于反离子与囊泡尺寸的结合减少所致。这对于目前正在尝试用阳离子双层系统进行的几种生物技术应用可能很重要。
