Towards Scaffolds for Rational Self Assembly: Investigating Nucleation Dependent Growth and Self-Healing of Co-Assembled Amyloid Nanotubes

ID：MPS/DMR/BMAT(7623) 0907435 PI：Berland，Keith ORG：埃默里大学标题：走向合理自组装的支架：研究共组装淀粉样蛋白纳米管的成核依赖性生长和自我修复智力优点：PI 观察到，在有序组装之前，淀粉样蛋白形成肽聚集成几微米尺寸聚集体的形态与有序纤维或纳米管不同，并且生长似乎源于肽构象的结构重组和这些聚集体结构内的相互作用。 这些初步数据代表了对淀粉样蛋白成核的首次直接观察，并致力于更深入地了解控制这些纳米材料的成核、生长和自愈特性的物理机制，对于推进它们作为功能性、合理设计的分子自组装平台的潜在用途至关重要。已经开发了一个模型系统，其中荧光肽被整合到高度有序的组装中，这些构建体为加深对组装基本途径的理解提供了独特的机会。通过将这种定义明确且结构特征明确的模型系统与最先进的荧光显微镜相结合，该研究计划能够极大地促进对这些材料的理解。具体来说，建议应用荧光成像、寿命成像、涨落光谱和光漂白测量来定义淀粉样蛋白成核、伸长和生长以及淀粉样蛋白纳米管的自愈特性。重点是： 目标 1：淀粉样蛋白成核。 表征淀粉样蛋白成核中涉及的聚集体结构、结构变化和相关动力学。这些测量将利用实验模型系统，该系统首次直接观察到淀粉样蛋白成核。目标 2：纳米管伸长和生长。 直接观察伸长动力学并对单个组件的生长速率进行定量测量，以更好地表征繁殖过程。这些测量可以确定生长是单向的还是双向的，并且与寿命显微镜相结合可以确定成熟的结构是直接组装的还是由初始组装后的松弛过程产生的。目标 3：淀粉样蛋白结构的肽交换和自我修复。有用的纳米级生物材料需要自我修复能力，受损区域可以重新组装或自我修复。初步证据表明淀粉样蛋白结构具有这种能力。这一目标侧重于了解自我修复机制所需的详细实验。 更广泛的影响：拟议的研究代表了埃默里大学 Berland（物理系）和 Lynn（化学系）实验室的合作成果。该研究的跨学科性质为埃默里大学社区内外提供了新的培训机会。教学和研究合作的优势在于学生接受了物理光谱、化学合成和跨学科研究课题所需的分析技术方面的培训。联合 PI 组织了一系列名为“订单的起源”的新生研讨会课程。 （埃默里大学研究人员的最新发现）向本科生介绍前沿研究。首席研究员和最近的一名博士后助理为本课程开发了材料，用于向新生教授荧光和波动及其在现代研究中的应用。 该提案的两位 PI 都有监督本科生研究项目的历史，每年提供学年和暑期学生培训。 除了埃默里大学社区之外，两位 PI 还利用研究实验室与大学外部的人员分享科学研究的热情和兴奋，包括与其他机构的研究人员以及高中生和高中教师进行互动。

ID: MPS/DMR/BMAT(7623) 0907435 PI: Berland, Keith ORG: Emory UniversityTitle: Towards Scaffolds for Rational Self Assembly: Investigating Nucleation Dependent Growth and Self-Healing of Co-Assembled Amyloid NanotubesINTELLECTUAL MERIT: The PIs have observed that prior to ordered assembly, the amyloid forming peptides aggregate into several-micron sized aggregates with morphology that is distinct from the ordered fibers or nanotubes, and that the growth appears to originate from structural reorganization of peptide conformations and interactions within these aggregate structures. These preliminary data represent the first direct observation of amyloid nucleation, and working towards a deeper understanding of the physical mechanisms governing nucleation, growth, and self-healing properties of these nanomaterials is essential for advancing their potential use as functional, rationally-designed platforms for molecular self-assembly. A model system has been developed in which fluorescent peptides are incorporated into the highly ordered assemblies, and these constructs provide a unique opportunity to deepen understanding of the fundamental pathways for assembly. By combining this well defined and structurally characterized model system with state-of-the-art fluorescence microscopy, the research plan has the capability to dramatically advance understanding of these materials. Specifically, it is proposed to apply fluorescence imaging, lifetime imaging, fluctuation spectroscopy, and photobleaching measurements to define amyloid nucleation, elongation and growth as well as the self-healing properties of amyloid nanotubes. The focus will be: Aim 1: Amyloid nucleation. Characterize aggregate structures, structural changes, and associated kinetics involved in amyloid nucleation. These measurements will exploit the experimental model system which has uncovered the first direct observation of amyloid nucleation. Aim 2: Nanotube elongation and growth. Directly observe elongation kinetics and make quantitative measurements of single assembly growth rates to better characterize propagation processes. These measurements can determine whether growth is uni- or bidirectional, and coupled with lifetime microscopy can determine whether mature structures are directly assembled or result from relaxation processes following initial assembly. Aim 3: Peptide exchange and self healing of amyloid structures. Useful nanoscale biomaterials require self-healing capabilities, by which damaged regions can reassemble or self-repair. Initial evidence suggests amyloid structures possess this capability. This aim focuses on detailed experiments that are required to understand the self-repair mechanisms.BROADER IMPACTS: The proposed studies represent a collaborative effort of the Berland (Department of Physics) and Lynn (Department of Chemistry) labs at Emory University. The interdisciplinary nature of the research provides the opportunity for new training opportunities, both within the Emory community and beyond. A strength of the teaching and research collaboration is that the students are trained in the physical spectroscopy, chemical synthesis, and the analysis techniques necessary to work on interdisciplinary research topics. The co-PI organizes a series of freshman seminar courses called ?Origins of ORDER? (On Recent Discoveries by Emory Researchers) that introduce undergraduate students to cutting edge research. The PI and a recent postdoctoral associate have developed materials for this course, which were used to teach freshmen about fluorescence and fluctuations, and their applications in modern research. Both PIs for this proposal have a history of supervising undergraduate research projects, providing academic year and summer student training each year. Beyond the Emory community both PIs have also used the research laboratory to share enthusiasm and excitement for scientific research with those outside the University, including interacting with researchers from other institutions as well as high school students and high school teachers.