Finite-Size Effects and Optimal System Sizes in Simulations of Surfactant Micelle Self-Assembly
Finite-Size Effects and Optimal System Sizes in Simulations of Surfactant Micelle Self-Assembly
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DOI：
10.1021/acs.jpcb.1c01186
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发表时间：
2021-05-07
影响因子：
3.3
通讯作者：
Straub, John E.
中科院分区：
文献类型：
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作者：
Harris, Jonathan J.;Pantelopulos, George A.;Straub, John E.
胶束在水溶液中的自发形成是由表面活性剂的两亲性决定的，由于胶束经常用作膜模拟物，用于蛋白质结构的表征，以及药物设计和递送，因此实际上很有趣。我们进行了系统的药物设计和递送。我们用粗粒度MARTINI模型对单组分十二烷基磷脂胆碱（DPC）胶束中观察到的有限尺寸效应进行了系统的表征。在使用大系统尺寸的多种粗粒度溶剂模型中，发现非极化溶剂模型最准确地再现了水溶液中100 mIVI DPC的SANS光谱。我们系统地研究了23个粒径为40-150 DPC的体系在恒定100 mM浓度下的有限尺寸效应，证实了有限尺寸效应表现为平均胶束聚集数随体系粒径的增加而振荡。当体系支持三个胶束形成时，聚集数的振荡基本减小。在估计的临界胶束浓度中观察到类似的振荡，平均值为1.10 mM，与实验值一致，为0.1 mM。利用MARTINI和CHARMM36使用多尺度模拟方法来避免胶束尺寸分布和SANS光谱的有限尺寸效应，利用多个长时间尺度500 DPC粗粒度模拟进行了探索，并将其反映射到CHARMM36全原子体系中。研究发现，MARTINI模型通常比全原子模型占据更大的体积，从而形成具有合理旋转半径但聚集数较小的胶束。本文对有限尺寸效应的系统描述和对多尺度模拟的探索，为胶束模拟的精确建模提供了指导。
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 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 mIVI DPC in aqueous solution. We systematically investigated the finite-size effect at constant 100 mM concentration in 23 systems of sizes 40-150 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. The oscillations in aggregation number mostly diminish once the system supports the formation of three micelles. Similar oscillations were observed in the estimated critical micelle concentration with a mean value of 1.10 mM, which is in agreement with experiment to 0.1 mM. The accuracy of using 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 time scale 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 allatom 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 provide guidance for the accurate modeling of micelles in simulations.