College of Chemistry and Chemical Enigineering, Xinjiang University , Urumqi, 830046, People's Republic of China.
Langmuir. 2013 Oct 29;29(43):13175-82. doi: 10.1021/la403257v. Epub 2013 Oct 15.
It has long been considered that the addition of cyclodextrins (CDs) disfavors the self-assembly of surfactants in dilute solutions since the hydrophobic effect is destroyed upon the formation of the hydrophiphilic CD/surfactant inclusion complex. However, in this work, we found that β-CD/nonionic surfactant inclusion complexes are able to self-assemble into vesicles in dilute solutions, namely in solutions with concentration lower than the CMC of surfactants. When using Tween 20 as a model surfactant, HNMR and MS measurements indicate that the building block for the vesicles is the channel type Tween 20@2β-CD inclusion complex. Structure and IR analysis suggests that the self-assembly of hydrophilic Tween 20@2β-CD is driven by H-bonds between both the headgroup of Tween 20 and the hydroxyl groups of β-CD. The self-assembly of the inclusion complex between the β-CD and the nonionic surfactant in dilute solution is found to be a general phenomenon. Undoubtedly, surfactant@2β-CD inclusion complex can be a novel building block for nonamphiphilic self-assembly, which provides a new physical insight for the influence of cyclodextrins on the self-assembly of surfactants.
长期以来，人们一直认为环糊精（CDs）的加入不利于表面活性剂在稀溶液中的自组装，因为在形成亲水性 CD/表面活性剂包合物时，疏水效应被破坏。然而，在这项工作中，我们发现β-CD/非离子表面活性剂包合物能够在稀溶液中自组装成囊泡，即在浓度低于表面活性剂 CMC 的溶液中。当使用 Tween 20 作为模型表面活性剂时，HNMR 和 MS 测量表明，囊泡的构建基块是通道型 Tween 20@2β-CD 包合物。结构和 IR 分析表明，亲水性 Tween 20@2β-CD 的自组装是由 Tween 20 的头基和β-CD 的羟基之间的氢键驱动的。在稀溶液中，β-CD 和非离子表面活性剂之间的包合物的自组装被发现是一种普遍现象。毫无疑问，表面活性剂@2β-CD 包合物可以作为非两亲自组装的新型构建基块，为环糊精对表面活性剂自组装的影响提供了新的物理见解。
