BMAT: Shape Driven Self-Assembly

ID: MPS/DMR/BMAT(7623) 0907428 PI: Fraden， Seth ORG: Brandeis标题：形状驱动的自我组装智力优点：本提案的目标是阐明一般原则，如何分子结构（大小，形状），分子性质（灵活性，电荷），分子相互作用（吸引力，排斥力），和悬浮液组成影响相行为。分子形状是控制相行为的基本性质。排除体积的概念描述了一个分子阻止另一个分子进入的空间区域。减少排除体积使分子运动更自由，从而增加熵。因此，分子受到影响，经历具有最小化排除体积的分子构型的相变。为了揭示熵在相变中的作用，PI将产生形状两亲体或熵表面活性剂，由两部分组成的分子分别具有相分离的倾向，但它们结合在一起形成嵌段共聚物。将创建两个实验系统。第一个胶体将由丝状病毒fd块形成，fd是一种长而薄的半柔性聚合物，可以形成液晶，而DNA是一种过于柔性而无法形成液晶的聚合物。第二个系统会是PRINT粒子吗？由合作者Joseph开发的高通量成型技术生产的纳米级胶体。德西蒙。将研究这些体系的相行为，以及形状两亲体与单个组分的混合物的相行为。熵是控制这些电荷稳定胶体相行为的主要特征。由于粒子间相互作用的大小、形状和简单性，可以对该系统进行高精度的理论建模和模拟。为了研究形状两亲体的相行为，PI将采用微流体装置PhaseChip，它可以精确地测量、混合和存储亚纳升量的样品、溶剂和其他试剂。成千上万个单独的混合物可以存储在单个井的芯片上。每口井都通过一层膜与储层接触，只有水可以通过，盐、聚合物或两亲化合物不能通过。这使得样品中所有溶质的浓度可逆、快速、精确地变化。更广泛的影响：该项目具有重要的科学意义，可以了解驱动自组装和决定组装最终架构的因素。该提案描述了一个已经高度发达的项目，用于对布兰代斯大学生命科学和生物物理学研究生进行跨学科培训，包括定量生物学的IGERT。积极鼓励本科生参与研究，研究生和本科生学习将微流体技术纳入生命科学研究。PI通过布兰代斯大学的POSSE项目参与了K-12的外展活动，该项目旨在将市中心的学生带到布兰代斯大学，并鼓励和支持他们在科学领域取得成功。

ID: MPS/DMR/BMAT(7623) 0907428 PI: Fraden, Seth ORG: Brandeis Title: Shape Driven Self AssemblyINTELLECTUAL MERIT: The objectives of this proposal are to elucidate general principles for how molecular architecture (size, shape), molecular properties (flexibility, charge), molecular interactions (attraction, repulsion), and suspension composition influence phase behavior. Molecular shape is a fundamental property governing phase behavior. The concept of excluded volume describes a region of space that one molecule prevents another from entering. Reducing excluded volume gives molecules more freedom of motion and thus increases entropy. Consequently molecules are influenced to undergo phase transitions that have molecular configurations which minimize excluded volume. In order to reveal the role of entropy in phase transitions the PI will create shape amphiphiles or entropic surfactants, molecules composed of two parts that separately have a tendency to phase separate, but which are bound together forming a block co-polymer. Two experimental systems will be created. The first colloid will be formed of blocks of the filamentous virus fd, a long, thin, semi-flexible polymer that forms liquid crystals and DNA, a polymer too flexible to form liquid crystals. The second system will be PRINT particles ? nanosized colloids produced by a high throughput molding technology developed by collaborator, Joseph. DeSimone. The phase behavior of these systems will be studied, as well as the phase behavior of mixtures of the shape amphiphiles with the individual components. Entropy is the dominant feature controlling the phase behavior of these charge stabilized colloids. Because of the size, shape, and simplicity of the interparticle interactions this system can be theoretically modeled and simulated with high precision. To study the phase behavior of shape amphiphiles the PI will employ a microfluidic device, the PhaseChip, which can precisely meter, mix, and store sub-nanoliter amounts of sample, solvent, and other reagents. Tens of thousands of individual mixtures can be stored on a chip in individual wells. Each well is in contact with a reservoir through a membrane through which only water can pass, but not salt, polymer, or amphiphile. This enables the concentration of all solutes in a sample to be reversibly, rapidly, and precisely varied.BROADER IMPACTS: This project has important scientific implications in terms of what will be learned about the factors that drive self assembly and determine the ultimate architecture of the assemblies. The proposal describes an already highly developed program for interdisciplinary training of Brandeis life science and biophysics graduate students, including an IGERT in Quantitative Biology. Undergraduate participation in research is actively encouraged, and both graduate and undergraduate students learn to incorporate microfluidics technology into life sciences research. The PI is involved in K-12 outreach through the Brandeis POSSE program designed to bring inner city students to Brandeis and to encourage and support their success in the sciences.