BMAT: Shape Driven Self-Assembly

ID：MPS/DMR/BMAT（7623）0907428 PI：Fraden，Seth ORG：Brandeis职务：形状驱动自组装智力优势：本提案的目标是阐明分子结构（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）和悬浮液组成如何影响相行为的一般原则。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。 减少排斥体积使分子有更多的运动自由，从而增加熵。因此，分子受到影响而经历具有使排除体积最小化的分子构型的相变。为了揭示熵在相变中的作用，PI将产生形状两亲物或熵表面活性剂，分子由两个部分组成，这两个部分分别具有相分离的趋势，但它们结合在一起形成嵌段共聚物。将建立两个实验系统。第一种胶体将由丝状病毒fd和DNA形成，丝状病毒fd是一种长而薄的半柔性聚合物，可以形成液晶，DNA是一种太柔性而不能形成液晶的聚合物。第二个系统将打印粒子？由合作者Joseph开发的高通量成型技术生产的纳米级胶体。德西蒙这些系统的相行为将被研究，以及形状的两亲物与单个组件的混合物的相行为。熵是控制这些电荷稳定胶体的相行为的主要特征。 由于颗粒间相互作用的大小、形状和简单性，该系统可以以高精度进行理论建模和模拟。为了研究形状两亲物的相行为，PI将采用微流体装置PhaseChip，该装置可以精确地计量、混合和存储亚纳升量的样品、溶剂和其他试剂。数以万计的单个混合物可以存储在单个威尔斯孔中的芯片上。每口井都通过一层膜与储层接触，只有水可以通过，而盐、聚合物或两亲物不能通过。这使得样品中所有溶质的浓度能够可逆地、快速地、精确地变化。更广泛的影响：这个项目具有重要的科学意义，因为它将了解驱动自组装的因素，并决定组装的最终结构。 该提案描述了一个已经高度发展的布兰代斯生命科学和生物物理学研究生跨学科培训计划，包括定量生物学IGERT。 积极鼓励本科生参与研究，研究生和本科生都学习将微流体技术纳入生命科学研究。 PI通过布兰代斯波塞计划参与K-12外展，该计划旨在将内城学生带到布兰代斯，并鼓励和支持他们在科学方面取得成功。

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.