胶束在水溶液中的自发形成受表面活性剂的两亲性质的支配，并且由于胶束作为膜模拟物的常规使用、用于蛋白质结构的表征以及用于药物设计和递送而实际上是有趣的。我们进行了系统的表征，在单组分十二烷基磷酸胆碱（DPC）胶束中观察到的有限尺寸效应与粗粒度的MARTINI模型。使用大系统尺寸的多个粗粒度的溶剂模型研究，非极化溶剂模型被发现最准确地再现SANS光谱的100 mM DPC在水溶液中。我们系统地研究了在恒定的100 mM浓度在23个系统的大小40至150 DPC的有限尺寸效应，确认有限尺寸效应表现为一个振荡的平均胶束聚集数的热力学聚集数作为系统的大小增加，主要是减少一旦系统支持形成三个胶束。采用多尺度模拟方法以避免使用MARTINI和CHARMM 36的胶束尺寸分布和SANS光谱中的有限尺寸效应的准确性使用多个长时间尺度500-DPC粗粒度模拟进行了探索，这些模拟被反向映射到CHARMM 36全原子系统。结果发现，MARTINI模型通常占据更多的体积比全原子模型，导致形成的胶束是一个合理的回转半径，但较小的聚集数。有限尺寸效应的系统表征和多尺度建模的探索在这项工作中提出的胶束模拟的准确建模提供了指导。
英文摘要：
The spontaneous formation of micelles in aqueous solutions is governed by the amphipathic nature of surfactants and is practically interesting due to the regular use of micelles as membrane mimics, for the characterization of protein structure, and for drug design and delivery. We performed a systematic characterization of the finite-size effect observed in single-component dodecylphosphocholine (DPC) micelles with the coarse-grained MARTINI model. Of multiple coarse-grained solvent models investigated using large system sizes, the non-polarizable solvent model was found to most-accurately reproduce SANS spectra of 100 mM DPC in aqueous solution. We systematically investigated the finite-size effect at constant 100 mM concentration in 23 systems of sizes 40 to 150 DPC, confirming the finite-size effect to manifest as an oscillation in the mean micelle aggregation number about the thermodynamic aggregation number as the system size increases, mostly diminishing once the system supports formation of three micelles. The accuracy of employing a multiscale simulation approach to avoid finite-size effects in the micelle size distribution and SANS spectra using MARTINI and CHARMM36 was explored using multiple long timescale 500-DPC coarse-grained simulations which were back-mapped to CHARMM36 all-atom systems. It was found that the MARTINI model generally occupies more volume than the all-atom model, leading to the formation of micelles that are of a reasonable radius of gyration, but are smaller in aggregation number. The systematic characterization of the finite-size effect and exploration of multiscale modeling presented in this work provides guidance for the accurate modeling of micelles in simulations.
Solubility of ionic surfactants below their Krafft point in mixed micellar solutions: Phase diagrams for methyl ester sulfonates and nonionic cosurfactants
