Single Molecule Studies of Topologically Complex Polymers

社会上使用的大多数材料都是基于世纪与线性聚合物相关的进步。下一个世纪将利用由具有更复杂几何形状的分子组成的材料，例如环或“编织”的环集合。使用先进的显微镜和相机观察单个分子，可以深入了解材料特性的分子起源，从而设计出更多的功能材料。因此，本项目的主要目的是使用DNA作为模型系统来研究环状聚合物和环状聚合物的集合，这些环状聚合物连接成一个链状几何形状。该项目还将包括重要的教育活动，包括开发演示材料和练习，向年轻学生介绍聚合物拓扑结构的概念，培训学生先进的制造技术，以及对代表性不足的学生进行结构化指导。线性DNA分子的单分子研究为聚合物物理，软物质和流变学领域提供了丰富的见解。人们对具有更复杂拓扑结构的聚合物产生了兴趣，这些拓扑结构可以转化为新的或增强的材料性能。 该项目将研究拓扑复杂聚合物的聚合物动力学和流变学，结合单分子DNA实验与模拟和理论。PI计划首先从单个环状聚合物的研究开始，然后转向环组装，即动质体中的链式DNA环网络。该项目有三个具体目标：（i）了解自缠结在环状聚合物中的作用，（ii）研究动质体在模型二维聚合物系统中的平衡动力学，以及（iii）研究动质体在微流体装置中的压缩和拉伸。 这项工作的一个重要特点是建立动塑体作为一个二维聚合物系统的单分子聚合物流变学研究，类似于什么已经做了二十多年的巨大成功与线性DNA。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

The majority of materials used in society are based on advances in the 20th century related to linear polymers. The next century will take advantage of materials which are composed of molecules with more complex geometries, such as rings or "knitted" collections of rings. Watching single molecules using advanced microscopes and cameras allows one to provide deep insights in the molecular origins of material properties and in turn design more functional materials. Therefore, the major aim of this project is to use DNA as a model system to study ring-like polymers and collections of ring polymers joined into a chainmail-like geometry. The project will also encompass significant educational activities, including developing demonstration materials and exercises to introduce young students to concepts of polymer topology, training students in advanced manufacturing techniques, and structured mentoring of under-represented students.Single molecule studies of linear DNA molecules have provided rich insights in the fields of polymer physics, soft matter, and rheology. There is an emerging interest in polymers with more complex topologies which can translate to new or enhanced material properties. This project will study the polymer dynamics and rheology of topologically complex polymers, combining single molecule DNA experiments with simulations and theory. The PI plans to first start with studies of single circular polymers and then move on to ring assemblies, namely catenated DNA ring net-works in kinetoplasts. The project has three specific objectives: (i) to understand the role of self-entanglement in ring polymers, (ii) to study the equilibrium dynamics of kinetoplasts in the con-text of a model two-dimensional polymer system, and (iii) to study the compression and stretching of kinetoplasts in microfluidic devices. An important feature of this work is to establish kinetoplasts as a two-dimensional polymer system for single molecule polymer rheology studies, akin to what has been done with great success for over two decades with linear DNA.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.