CAREER: Directed Epitaxial Assembly of Structural Biopolymers in Hierarchical Mesostructures for Enhanced Mechanical Behavior, Mass Transport and Heat Transfer

这个学院早期职业发展计划（Career）奖支持基础研究，使新的纳米制造范式能够在中尺度（50-500纳米）上赋予纳米结构材料分层组织，这种范式已经被生物体掌握。当前的纳米制造过程涉及复杂的时间和能量消耗步骤，需要对装配环境进行细致的调节，并且通常不允许跨越长度尺度（从纳米到宏观）的分层组织。该项目研究了定向外延组装，该组装能够使用生命的构建块（如丝绸）高效地制造分层介结构材料。这种能力允许在三维材料中集成介尺度特征，并制造具有增强机械，传热和质量传递特性的多功能材料。事实上，分层介观结构材料是一种新型材料，在下一代高科技材料的设计中越来越重要。此外，对天然聚合物中纳米级组装现象的基本理解将生物物质的制造规则与技术联系起来。该项目的成果有可能极大地影响国民经济和一般福利，并在美国国家科学基金会的“人类技术前沿工作的未来大构想”和“理解生命规则”中产生分支。此外，该研究涉及纳米制造、材料科学、蛋白质工程、热力学和生物化学的跨学科性质，有助于扩大年轻科学家和未被充分代表的群体在研究中的参与，并对工程教育产生积极影响。这个CAREER项目的目标是理解和利用力和场的协调，使结构生物聚合物的纳米制造能够在分层介结构材料中实现，模仿生物体中发生的过程。这种基本的理解定义了一种新的纳米制造范式，使得在中尺度形成复杂的结构成为可能。实现这一愿景的主要障碍是对调节生物聚合物组装的现象的理解不足，以及缺乏在复杂系统中混合自下而上和自上而下方法的制造技术。在这项研究中，热力学原理、定向组装、增材制造和蛋白质工程为探索和利用结构蛋白的折叠、组装和融合提供了基本工具。特别是，结构蛋白（如丝）的外延生长在纳米尺度上进行了研究，使用的设计原则是将多肽的序列-结构-组装特性联系起来，并允许它们用作模板和指导组装过程的种子材料。这种基本的理解使基于生物聚合物的分层介观结构材料的纳米制造成为可能，这是当前纳米制造技术无法实现的，它表现出增强的韧性和弹性，选择性质量传输和模块化散热，影响了生物医学，农业，航空航天，汽车，微电子和能源应用的几个技术领域。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This Faculty Early Career Development Program (CAREER) award supports basic research that enables a new nanomanufacturing paradigm, which has been mastered by living organisms, to impart hierarchical organization at the mesoscale (50-500 nanometers) to nanostructured materials. Current nanomanufacturing processes involve complex time- and energy-consuming steps, require meticulous regulation of the assembly environment, and, generally do not allow hierarchical organization across length-scales (from nano to macro). This project investigates directed epitaxial assembly that enables the efficient fabrication of hierarchical mesostructured materials using the building blocks of life -- like silk. Such a capability allows integration of mesoscaled features in three-dimensional materials and the manufacture of multifunctional materials with enhanced mechanical, heat transfer and mass transport properties. Hierarchical mesostructured materials are, in fact, a new class of materials with increasing importance in the design of the next generation of high tech materials. Additionally, the basic understanding nanoscale assembly phenomena in natural polymers liaises the rules of fabrication in living matter with technology. The outcomes of this project have the potential to greatly impact national economy and general welfare, with ramification in the NSF's Big Ideas of the Future of Work at the Human-Technology Frontier and Understanding the Rules of Life. Furthermore, the interdisciplinary nature of the study, which involves nanomanufacturing, material science, protein engineering, thermodynamics and biochemistry, helps broaden participation of young scientists and underrepresented groups in research and positively impact engineering education.The objective of this CAREER project is to understand and exploit the orchestration of forces and fields that enable the nanomanufacturing of structural biopolymers in hierarchical mesostructured materials, mimicking processes that occur in living organisms. This basic understanding defines a new nanomanufacturing paradigm that enables the formation of complex architectures at the mesoscale. The major barriers to this vision are a poor understanding of the phenomena that modulate biopolymer assembly and the lack of fabrication techniques that blend bottom-up and top-down approaches in complex systems. In this study, thermodynamic principles, directed assembly, additive manufacturing and protein engineering provide the basic tools to explore and harness structural proteins folding, assembly and fusion. In particular, epitaxial growth of structural proteins, e.g., silk, is studied at the nanoscale using design principles that liaise the sequence-structure-assembly properties of polypeptides and that allow for their use as seed materials to template and direct assembly processes. This basic understanding enables the nanomanufacturing of biopolymer-based hierarchical mesostructured materials, unattainable with current nanomanufacturing techniques, that exhibit enhanced toughness and resilience, selective mass transport and modular heat dissipation, impacting several technological fields that span biomedical, agriculture, aerospace, automotive, microelectronics and energy applications.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.