Translocation and phase separation kinetics in polyelectrolyte solutions

带电大分子在拥挤的水溶液中的运动和这种多组分大分子系统的热力学稳定性在各种形式的生命中至关重要。水溶液的热力学和动力学行为表现出极其复杂的现象学，并提出了许多基本的理解挑战。该提案是执行电生理学和光散射实验有关的基本理解（a）通过蛋白质和固态纳米孔的单重分子的易位，（B）在重离子溶液中的相分离动力学，和（c）在重离子凝胶中伴随相变的弹性模式的动力学。具体而言，建议的研究地址（a）具有指定架构的区块链的动力学（均匀带电的线性分子、带电和不带电聚合物的二嵌段共聚物、支化聚电解质和嵌段复合物）通过纳米孔（具有固定孔径的溶血素蛋白质孔和具有可控直径变化的氮化硅孔），（B）聚（苯乙烯磺酸）钠在含有已知量氯化钡的水中的相分离动力学，和（c）聚丙烯酰胺-聚丙烯酸共聚物凝胶伴随其一级体积相变的动力学波动。拟议的研究将建立一些新发现的现象的有效性和普遍性，这些现象与合成的疏水分子通过蛋白质孔的移位、带电聚合物溶液中的相分离机制以及凝胶中弹性模式的过渡前减慢有关。拟议的研究将对分离科学、水介质中带电大分子的表征方法、医学研究以及包括食品、化妆品、个人护理产品、药品和人类基因组测序计划。 聚电解质是最重要但了解最少的材料之一。这项研究将使用许多实验方法以及理论和模拟，试图了解生物分子如何能够通过蛋白质组装体和其他生物系统中的孔。 在这一高度跨学科的研究领域培养研究生是拟议活动的主要教育组成部分。

TECHNICAL SUMMARY:The movement of charged macromolecules in crowded aqueous solutions and the thermodynamic stability of such multi-component macromolecular systems are of central importance in various forms of life. The thermodynamic and dynamic behaviors of polyelectrolyte solutions in water exhibit extremely complex phenomenology and pose many challenges for a fundamental understanding. The proposal is to perform electrophysiology and light scattering experiments pertinent to a fundamental understanding of (a) translocation of single polyelectrolyte molecules through protein and solid-state nanopores, (b) kinetics of phase separation in polyelectrolyte solutions, and (c) dynamics of elastic modes accompanying phase transitions in polyelectrolyte gels. Specifically, the proposed research addresses (a) the dynamics of polyelectrolyte chains with specified architecture (uniformly charged linear molecules, diblock copolymers of charged and uncharged polymers, branched polyelectrolytes, and polyelectrolyte complexes) through nanopores (hemolysin protein pore with fixed pore diameter and silicon nitride pores with controllable variations in diameter), (b) phase separation kinetics of sodium poly(styrene sulfonate) in water containing known amounts of barium chloride, and (c) dynamical fluctuations of polyacrylamide-polyacrylic acid copolymer gels accompanying their first order volume phase transitions. The proposed research will establish the validity and generality of a few newly discovered phenomena related to translocation of synthetic polyelectrolyte molecules through protein pores, phase separation mechanism in electrically charged polymeric solutions, and pretransitional slowing down of elastic modes in gels.NON-TECHNICAL SUMMARY:The proposed research will have impact in separation science, characterization methods for charged macromolecules in aqueous media, and medical research, and a number of key industries including food, cosmetics, personal care products, pharmaceuticals, and the human genome sequencing project. Polyelectrolytes are among the most important but least understood materials. This research will use a number of experimental methods together with theory and simulations in an attempt to understand how polyelectrolyte molecules are able to pass through pores in protein assemblies and other biological systems. Training of graduate students in this highly interdisciplinary research area is the primary educational component of the proposed activity.