Structural analysis of a calix[4]arene-based Platonic Micelle
Structural analysis of a calix[4]arene-based Platonic Micelle
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DOI：
10.1038/s41598-018-38280-1
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发表时间：
2019-02
影响因子：
4.6
通讯作者：
E. Mylonas;N. Yagi;Shota Fujii;Kodai Ikesue;T. Ueda;H. Moriyama;Yusuke Sanada;K. Uezu;K. Sakurai;T. Okobira
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作者：
E. Mylonas;N. Yagi;Shota Fujii;Kodai Ikesue;T. Ueda;H. Moriyama;Yusuke Sanada;K. Uezu;K. Sakurai;T. Okobira
我们最近引入了“柏拉图胶束”的概念，球形胶束对特定聚集数的偏好大多与柏拉图固体的面数一致。这种影响在体积较大、主要是杯[4]芳烃为基础的表面活性剂体系中观察到，聚集数较小。首选的聚集数会导致更好的球体覆盖率、更高的填充量和疏水核心对水溶液的“保护”，这是这一偏好的最重要因素。在目前的研究中，我们进一步探索了驱动高电荷PACaL3表面活性剂堆积到高度对称的六面体胶束中的相互作用。我们进行了一系列分子动力学模拟，得到了一大组结构，并选择了与实验小角X射线散射数据很好一致的系综。具有适当尾长和头基体积的杯[4]芳烃的几何构型和刚性是胶束高度对称性和单分散性的驱动力。头基的电荷主要起到抑制高阶结构形成的作用。钠对胶束的稳定性很重要，但并不直接与胶束相互作用，这意味着杯[4]芳烃环是C2ν对称构象。
We have recently introduced the concept of “Platonic micelles”, the preference of spherical micelles to specific aggregation numbers mostly coinciding with the number of faces of platonic solids. This effect was observed on bulky, mostly calix[4]arene-based surfactant systems with small aggregation numbers. The preferred aggregation numbers result in better sphere coverage, highliting the packing and the “protection” of hydrophobic cores from the aqueous solvent as the most important factor for this preference. In the present study we further explore the interactions that drive the packing of the highly charged PACaL3 surfactant into highly symmetrical hexameric micelles. We performed a series of molecular dynamics simulations that yielded a large set of structures and an ensemble in good agreement with the experimental Small Angle X-ray Scattering data was selected. The geometry and the rigidity of the calix[4]arene group with proper tail length and headgroup volume are the driving forces for the high symmetry and monodispersity of the micelle. The charge of the headgroups is mainly responsible for inhibiting the formation of higher order structures. Sodium, shown to be important for the stability of the micelle, is not directly interacting with the micelle implying that the calix[4]arene ring is a C2ν symmetry conformation.