Shape and Dimensional Precision in Polymeric Nanostructures

聚合物纳米结构的形状和尺寸精度

• 批准号: 0605427
• 负责人: Samuel Stupp
• 金额: $ 36万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2010-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0605427&HistoricalAwards=false
• 关键词: Shape; Dimensional; Precision; Polymeric; Nanostructures

TECHNICAL SUMMARY: Precise dimension and shape control remains a great challenge in the design of nanoscale organic structures. This program studies two different strategies toward precise control over size and shape in supramolecular assemblies. One approach involves the use of molecular templates to truncate one-dimensional self-assembled structures, and a second one explores the use of mechanical forces to spontaneously terminate the growth of assemblies or determine their precise shape and size. In the first approach synthetic dumbbell-shaped molecules with a rigid and hydrophobic linear core are proposed as templates to dictate the length of assemblies formed by peptide amphiphiles. The hydrophobic segments of these molecules should be attracted to the template core and growth of the assembly limited by the hydrophilic termini of the template. In terms of function, it is also of interest to investigate the electronic properties of these assemblies, as well as their ability to encapsulate active molecules with reproducible stoichiometry. The second approach examines two problems, the use of supramolecular strain mechanics to define helical shape in one-dimensional nanostructures and also to define the shape of nanostructures shaped as platonic solids. The first problem utilizes charged peptide lipid molecules in which bulky groups strain the b-sheets formed when self-assembly occurs in organic solvents. Preliminary studies have shown that bulky endgroups attached to the periphery of b-sheets cause nanofibers to relax into helical nanostructures with pitch determined by sterics. The research will validate this model and also study the use of templates to obtain precise assemblies. In the second problem, the challenge is to achieve precise definition of three-dimensional structures. The goal in the program is to construct structures with non-spherical geometries similar to natural virus capsids. Mixtures of oppositely charged amphiphilic molecules containing various types of rigid and hydrophobic segments are proposed as a strategy to assemble nanoscale platonic solids such as icosahedral objects. In these objects supramolecular strains associated with curvature could lead to packing with planar facets.NON-TECHNICAL SUMMARY: Learning from the complex structure formations seen in nature has been one of the major goals of synthetic chemistry. Ultimately, this would not only allow us to design materials more effective in "human repair", but it would also enable us to construct artificial molecular machinery to carry out processes important for modern technology, for example in electronic and sensing devices. This is a subject requiring interdisciplinary research and links to other scientists around the world. The work cuts across physical sciences, life sciences, and engineering disciplines, and it is therefore an excellent platform for education of future scientists and for international collaborations. As a step toward this goal, the research proposed herein involves accurately controlling the shape and size of several self-assembling polymers previously discovered in this laboratory. This program explores two approaches toward this goal. One involves the use of molecules as external templates to dictate the dimension of the assemblies. The other approach programs assemblies through the molecular structure of building blocks to form nanostructures with non-spherical shapes similar to those acquired by viruses.

技术概述：在纳米级有机结构设计中，精确的尺寸和形状控制仍然是一个巨大的挑战。该程序研究了两种不同的策略，以精确控制超分子组装的大小和形状。一种方法涉及使用分子模板截断一维自组装结构，另一种方法探索使用机械力来自发地终止组装的生长或确定其精确的形状和大小。在第一种方法中，提出了具有刚性疏水线性核心的合成哑铃形分子作为模板来指示肽两亲体形成的组装的长度。这些分子的疏水部分会被吸引到模板核上，组装体的生长受到模板亲水末端的限制。在功能方面，研究这些组件的电子特性以及它们封装具有可重复化学计量的活性分子的能力也很有趣。第二种方法研究了两个问题，使用超分子应变力学来定义一维纳米结构中的螺旋形状，以及定义形状为柏拉图固体的纳米结构的形状。第一个问题是利用带电荷的肽脂分子，其中庞大的基团使在有机溶剂中发生自组装时形成的b片应变。初步研究表明，附着在b片外围的庞大端基导致纳米纤维松弛成螺旋纳米结构，其螺距由位向决定。该研究将验证该模型，并研究使用模板来获得精确的装配。在第二个问题中，挑战是实现三维结构的精确定义。该计划的目标是构建具有类似于天然病毒衣壳的非球形几何结构。将带相反电荷的两亲分子混合在一起，其中包含各种类型的刚性和疏水性片段，作为组装纳米级柏拉图固体（如二十面体物体）的一种策略。在这些物体中，与曲率相关的超分子应变可能导致平面表面的堆积。非技术总结：从自然界中看到的复杂结构中学习一直是合成化学的主要目标之一。最终，这不仅将使我们能够设计出更有效的“人体修复”材料，而且还将使我们能够构建人工分子机器来执行对现代技术（例如电子和传感设备）至关重要的过程。这是一个需要跨学科研究和与世界各地其他科学家联系的课题。这项工作涉及物理科学、生命科学和工程学科，因此是培养未来科学家和国际合作的绝佳平台。作为实现这一目标的一步，本文提出的研究包括精确控制先前在该实验室发现的几种自组装聚合物的形状和大小。本节目探讨了实现这一目标的两种方法。一种方法是使用分子作为外部模板来决定组件的尺寸。另一种方法是通过构建块的分子结构编程组装，形成与病毒获得的非球形纳米结构相似的纳米结构。