Elucidating the Unique Self-Assembly Behavior of Macroions in Solution From Molecular Level Modeling

自组装是单个分子构件之间的特定作用力导致有序结构自发形成的过程。分子自组装在自然界中普遍存在，从雪花的结晶到核糖体和病毒。分子自组装已经成为化学合成中的一种新方法，它提供了一系列具有科学意义和技术重要性的材料的路线。在化学系大分子、超分子和纳米化学计划的支持下，阿克伦大学的Mesfin Tsige教授正在利用计算机模拟来研究具有多个电荷的超大分子(称为大离子)在溶液中的自组装行为。计算机模拟跟踪了数万到数十万颗珠子的运动，每个珠子代表几个原子，因为它们自发形成了巨大的复杂结构。从这些模拟中，Tsige教授和他的团队正在发展对宏观离子自组装的基本理解，这几乎完全是理论和模拟所未知的。该项目涉及阿克伦大学的研究生和博士后助理，以及通过NSF-聚合物科学和聚合物工程学院本科生研究体验(REU)网站的本科生，以及来自当地圣文森特-圣彼得堡的高中生。玛丽学校。该项目通过提供实验室测量难以或有时不可能获得的信息，对现有的实验研究进行了补充。该项目的核心是开发一种通用的粗粒度计算机模拟模型，该模型专为大规模分子动态模拟而设计。一个典型的模拟跟踪了在超过5000万个时间步长的过程中，25-50个大离子被100,000-200,000个溶剂分子包围，自组装成大的“黑莓”结构。Tsige教授和他的学生一起使用计算机模型来阐明组装形成的机制，并了解电荷密度、电荷分布、宏离子大小和溶剂极性对自组装行为的影响。这种建模方法可能会促进我们对大离子溶液中自组装的理解，这些大离子溶液涵盖了化学、材料科学和生物学的各个领域。

Self-assembly is the process by which specific forces between individual molecular building blocks leads to the spontaneous formation of ordered structures. Molecular self-assembly is ubiquitous in nature from the crystallization of snowflakes to ribosomes and viruses. Molecular self-assembly has emerged as a new approach in chemical synthesis, providing routes to a range of materials that are both scientifically interesting and technologically important. With the support of the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Professor Mesfin Tsige of the University of Akron is using computer simulation to investigate the self-assembly behavior of very large molecules with multiple charges (called macroions) in solution. The computer simulation tracks the motion of tens of thousands to hundreds of thousands of beads, each representing a few atoms, as they spontaneously form large complex structures. From these simulations, Professor Tsige and his group are developing a fundamental understanding of the self-assembly of macroions that are almost completely uncharted by theory and simulation. The project involves graduate students and postdoctoral associates at the University of Akron, as well as undergraduate students through the NSF-Research Experiences for Undergraduates (REU) site at the College of Polymer Science and Polymer Engineering, and high school students from the local St. Vincent-St. Mary School. The project complements existing experimental studies by providing information that is difficult or sometimes impossible to get from laboratory measurements. Central to the project is the development of a versatile coarse-grained computer simulation model that is designed for large-scale molecular dynamic simulation. A typical simulation tracks the self-assembly of 25-50 macroions surrounded by 100,000-200,000 solvent molecules into large 'blackberry-like' structures over the course of over 50 million time steps. Together, Professor Tsige and his students are using the computer model to elucidate the mechanism of assembly formation and understand the effects of charge density, charge distribution, macroion size, and solvent polarity on self-assembly behavior. This modeling methodology may advance our understanding of self-assembly in a broad range of macroion solutions, which cover a variety of fields in Chemistry, Material Science, and Biology.