Key Laboratory of Colloid & Interface Chemistry (Ministry of Education), Shandong University, Jinan, 250100, P. R. China.
National Engineering Technology Research Center of Colloidal Materials, Shandong University, Jinan 250100, P. R. China.
Soft Matter. 2022 Mar 9;18(10):2072-2081. doi: 10.1039/d1sm01753e.
We recently found that rough glass surfaces (RGSs) can mediate the micelle-to-vesicle transition in single-component solutions of simple single-tailed amphiphiles (STAs), but only result in a relatively small number of vesicles coexisting with a large number of micelles. In the current work, a dehydration-rehydration (DHRH) method was used to induce the formation of vesicles in the single-component aqueous solutions of alkyltrimethylammonium bromides (CTABs, = 12, 14, and 16), a kind of typical cationic STAs. That is, a CTAB micelle solution dropped on smooth glass surfaces (SGSs) was first dried, and the dried CTAB aggregates were then rehydrated in a monomer solution of CTAB. A large population of vesicles and even pure vesicle (or vesicle-dominated) systems were obtained, indicating that the DHRH process could more effectively induce the formation of STA vesicles than RGS mediation. The so-obtained vesicles were characterized using DLS, FF-/cryo-TEM, AFM, SAXS, and fluorescence techniques, and their stability was determined. In addition, the effects of the conditions of DHRH and the chain length of CTABs on the vesicle formation were examined. It was demonstrated that the vesicles can be formed as long as the concentrations of CTABs in the rehydrated systems are higher than their critical micelle concentrations. The size and wall thickness of vesicles increase with an increase in chain length. A possible mechanism for the DHRH-induced vesicle formation is proposed: bilayer sheets are formed on SGSs during dehydration, and then detached from the SGSs to form vesicles during rehydration. A highly interdigitated structure of alkyl chains between two leaflets was identified in the bilayers, which probably is the origin of the formation and stability of STA vesicles.
我们最近发现，粗糙玻璃表面（RGS）可以介导单组分单尾两亲分子（STA）胶束到囊泡的转变，但仅导致相对少量的囊泡与大量胶束共存。在目前的工作中，采用脱水-再水合（DHRH）方法诱导烷基三甲基溴化铵（CTAB， = 12、14 和 16）的单组分水溶液形成囊泡，CTAB 是一种典型的阳离子 STA。即，将 CTAB 胶束溶液滴在光滑玻璃表面（SGS）上，首先干燥，然后将干燥的 CTAB 聚集体再水化到 CTAB 的单体溶液中。得到了大量的囊泡，甚至是纯囊泡（或囊泡主导）体系，表明 DHRH 过程比 RGS 介导更有效地诱导 STA 囊泡的形成。使用 DLS、FF-/冷冻-TEM、AFM、SAXS 和荧光技术对所得到的囊泡进行了表征，并确定了其稳定性。此外，还考察了 DHRH 条件和 CTAB 链长对囊泡形成的影响。结果表明，只要再水化体系中 CTAB 的浓度高于其临界胶束浓度，就可以形成囊泡。囊泡的尺寸和壁厚随链长的增加而增加。提出了一种 DHRH 诱导囊泡形成的可能机制：在脱水过程中，双层片在 SGS 上形成，然后在再水合过程中从 SGS 上脱离形成囊泡。在双层片中鉴定出两亲分子烷基链之间高度交错的结构，这可能是 STA 囊泡形成和稳定的原因。
