Phase behavior of complex coacervates

威斯康星大学麦迪逊分校的Arun Yethiraj获得了化学系化学理论、模型和计算方法计划以及材料研究部凝聚物质和材料理论计划颁发的奖项，以研究复杂凝聚体的相行为。聚合物是广泛存在于塑料和生物中的长链状分子，如DNA和蛋白质。带正电和带负电的聚合物的混合物，称为凝聚体，可以形成单独的稠密液相的“液滴”。一个例子是活细胞中由RNA和蛋白质组成的微米级组装，这与许多生物过程有关。它们也可能在生命的起源中发挥作用，因为这些液滴可以在没有类脂的情况下形成，而核酸可能在早期宇宙中促进了催化作用。这些混合物在材料科学中也很有兴趣，它们在药物递送剂、涂层和粘合剂中有应用。它们因其迷人的性质而引起人们的根本兴趣，而获得化学、结构和性质之间的关系是一项具有挑战性的任务。Yethiraj教授和他的团队正在使用一系列理论和计算方法研究这种相行为的机制，目的是了解这种相分离的原理以及如何控制它。他的团队参与指导初中和高中的科学奥林匹克团队，并让他们参与现代计算方法。耶提拉杰教授和他的团队正在研究两种平行的方法来研究复杂的凝聚体。首先，他们从第一性原理发展出原子化的、完全可极化的力场，并用这些来标记粗粒度模型。他们正在使用这些方法通过计算机模拟来研究构象和结构特性。第二，他们正在开发和实施分子经典密度泛函理论，该理论可以通过模拟进行验证，然后用来获得相行为。结果将是一套有效的工具，可用于研究任何复杂的聚合物溶液和对凝聚机理的理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Arun Yethiraj of the University of Wisconsin-Madison is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry and the Condensed Matter and Materials Theory program in the Division of Materials Research to study the phase behavior of complex coacervates. Polymers are long chain like molecules that are ubiquitous in applications, e.g., plastics, and in biology, e.g., DNA and proteins. Mixtures of positively and negatively charged polymers, called coacervates, can form "droplets" of a separate dense liquid phase. An example is micron-sized assemblies composed of RNA and proteins in living cells that are implicated in many biological processes. They might also play a role in the origin of life, because these droplets can form in the absence of lipids, and the nucleic acids could have promoted catalysis in the early universe. These mixtures are also of interest in materials science where they find applications in drug delivery agents, coatings, and adhesives. They are of fundamental interest because of their fascinating properties, and obtaining relationships between the chemistry, structure, and property is a challenging task. Professor Yethiraj and his group are studying the mechanism of this phase behavior using an array of theoretical and computational methods, with the aim of understanding the principles of this phase separation and how it might be controlled. His group is involved in coaching middle and high school science Olympiad teams, and involving them in modern computational methods.Professor Yethiraj and his group are working on two parallel approaches for the study of complex coacervates. In the first they are developing atomistic, fully polarizable force-fields from first-principles, and using these to bench-mark coarse-grained models. They are using these to study the conformational and structural properties using computer simulations. In the second they are developing and implementing molecular classical density functional theory which can be tested against simulations and then used to obtain the phase behavior. The outcome will be a set of efficient tools that can used to study any complex polymer solution and an understanding of the mechanism of coacervation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.