Department of Chemistry, Università La Sapienza, Rome, Italy.
J Phys Chem B. 2010 Jun 24;114(24):8056-60. doi: 10.1021/jp100437v.
Sodium dodecylsulfate (SDS) and cetyltrimethylammonium bromide (CTAB) dispersed in aqueous solution form catanionic vesicles. Depending on composition, such vesicles show different net charge, stability, and interaction capability, indicative of the strong impact that catanionic systems may have in gene therapy and drug delivery technologies. To reveal the interplay among composition, net charge, sensitivity to temperature changes, vesicle size, and inner structure, a series of experiments on catanionic vesicles prepared at different SDS/CTAB mole ratios was performed. Dynamic light scattering, small-angle X-ray scattering, and zeta-potential experiments allow one to characterize an unexpected critical phenomenon at the nanoscale level. On heating, vesicles increase in size, but at a critical temperature an abrupt vesicle size reduction has been observed, together with a transition from multi- to a unilamellar state. The critical temperature regularly depends on the SDS/CTAB mole ratio. The unilamellar state obtained upon heating is retained for weeks. These phenomena suggest a new way to produce stable unilamellar vesicles with tunable size and charge.
十二烷基硫酸钠（SDS）和十六烷基三甲基溴化铵（CTAB）在水溶液中分散形成混合囊泡。根据组成的不同，这些囊泡表现出不同的净电荷、稳定性和相互作用能力，这表明混合囊泡系统可能对基因治疗和药物输送技术有很大的影响。为了揭示组成、净电荷、对温度变化的敏感性、囊泡大小和内部结构之间的相互作用，我们在不同 SDS/CTAB 摩尔比下制备了一系列混合囊泡，并进行了一系列实验。动态光散射、小角 X 射线散射和 ζ 电位实验允许在纳米尺度上对一个意想不到的临界现象进行表征。加热时，囊泡会增大，但在临界温度下，观察到囊泡大小的突然减小，同时从多室状态转变为单室状态。临界温度通常取决于 SDS/CTAB 的摩尔比。加热后得到的单室状态可以保持数周。这些现象为制备具有可调尺寸和电荷的稳定单室囊泡提供了一种新方法。
