Engineering phases and kinetics for processing DNA-linked particle materials

知识价值：DNA被认为是一种有效的方法，可以对微观粒子集合进行编程，使其自组装成所需的结构。这个想法非常简单：携带互补DNA链的粒子物种会粘在一起，而使互补物种之间的接触最大化的有序结构会从混合物中自发地自我组装起来。不幸的是，预编程结构的概念并不适用于实现大量有用的dna连接颗粒材料（dlpm）。例如，它不是真正的原子材料是如何工作的：通常有几种不同的晶体结构，它们是系统自由能的局部最小值，在规定的条件下实际形成的结构取决于相对成核和生长速率，以及不同相之间可能的固-固转变。此外，任何有序结构的质量，由形态和成分缺陷的密度定义，受到各种加工变量的强烈影响，如成核和生长过程中的热历史。在这里，pi建议将dlpm建立为一个实用的材料类别的正确途径是在扩展的设计范式的背景下同时考虑材料和工艺。因此，本提案的总体智力目标是：(1)利用实验和预测计算机模拟建立对二元dlpm的成核和生长热力学和动力学的定量理解(2)证明处理dlpm的能力与任何其他材料一样，即通过开发控制成核，生长，以及利用热或化学刺激来实现这些目标的任何潜在的固-固转变，我们的目标是开发一个实验系统，使实时的实时空间光学显微镜能够对具有可调粒子间相互作用的二元dlpm进行动态分析。实验工作将与全面的计算机模拟工作紧密结合，这将阐明基本机制并提供材料-过程组合的高通量分析。更广泛的影响：原则上，被称为超材料的新材料，由有组织的阵列和光学活性纳米粒子电路组成，而不是原子，有望使光子具有与微电子技术为计算带来的相同密度和多功能性。这将缓解目前微电子和光纤通信之间的光电技术瓶颈，并使新的信息技术成为可能。主要的挑战是制造这些革命性的新材料。该项目将开发和验证用于生产复杂有序颗粒复合材料的通用自组装设计和材料加工平台。预计从这个项目中产生的设计规则将直接适用于制造有用的超材料。如果光学活性粒子与DNA组装在一起，所得到的材料可以用作原型和概念研究的证明，或者作为转换为更适合应用的固体复合材料的模板。这个跨学科的项目将为研究生和本科生提供充足的培训机会。这两个研究生主要参与这个项目将被期望积极参与计算和实验方面。学生将接触到一个国家的最先进的工具包，其中包括纳米粒子和胶体功能化，先进的显微镜和各种数值模拟和模拟技术。而且，仿真和实验数据的丰富性、目标性，及其在技术上的潜在应用前景令人瞩目。定向自组装将促进费城公立学校高中生的推广工作，并传达科学研究的兴奋。Sinno和Crocker都越来越积极地参与宾大和周边机构的各种推广活动，这个项目将为这些努力提供额外的材料。

1133386CrockerIntellectual Merits: DNA has been suggested as an effective way to program collections of microscopic particles to self-assemble into desired structures. The idea is appealingly simple: particle species bearing complementary DNA strands will stick together, and the ordered structure that maximizes such contacts between complementary species will self-assemble spontaneously from the mixture. Unfortunately, the notion of pre-programmed structure is not appropriate for realizing a broad array of useful DNA-linked particle materials, or DLPMs. It is not, for instance, how real atomic materials work: there are typically several different crystal structures that are local minima of a systems free energy, and what structure actually forms under prescribed conditions depends on relative nucleation and growth rates, and possible solid-solid transformations between different phases. Moreover, the quality of any resulting ordered structure, as defined by the density of morphological and compositional defects, is strongly influenced by a variety of processing variables such as the thermal history during nucleation and growth. Here, the PIs propose that the correct pathway to establish DLPMs as a practical material class is to consider simultaneously both materials and processes in the context of an expanded design paradigm. The overarching intellectual goals of this proposal are therefore (1) to establish a quantitative understanding of the nucleation and growth thermodynamics and kinetics of binary DLPMs using experiments and predictive computer simulations (2) to demonstrate the ability to process DLPMs much in the same way as any other material, i.e. by developing approaches for controlling nucleation, growth, and any potential solid-solid transformations using thermal or chemical stimuli to achieve these goals, we aim to develop an experimental system to enable real time real space optical microscopy for dynamical analysis of binary DLPMs with tunable interparticle interactions. The experimental work will be coupled closely to a comprehensive computer simulation effort that will elucidate fundamental mechanisms and provide high-throughput analysis of material-process combinations.Broader Impacts:In principle, new materials called metamaterials, formed of organized arrays and circuits of optically active nanoparticles instead of atoms, promise to allow the manipulation of photons with the same density and versatility that microelectronics brings to computation. This would alleviate the current optoelectronic technology bottleneck between microelectronics and fiber optic telecommunications as well as enable new information technologies. The primary challenge is building these revolutionary new materials. This project will develop and validate a general self-assembly design and material processing platform for producing complex, ordered particle composite materials. It is anticipated that the design rules that emerge from this project will be directly applicable to the making useful metamaterialsif optically active particles are assembled with DNA, the resulting material can be used as is for prototyping and proof of concept studies, or alternatively, as a template for conversion into a solid composite material more appropriate for applications.This interdisciplinary project will provide ample opportunities for student training at both the graduate and undergraduate levels. The two graduate students principally involved in this project will be expected to be actively involved in both the computational and experimental facets. Students will be exposed to a state-of-the-art toolkit which includes nanoparticle and colloidal functionalization, advanced microscopy and various numerical modeling and simulation techniques. Moreover, the rich, visual nature of the simulation and experimental data, and their potential application in remarkable technology. directed self-assembly will facilitate outreach efforts to high-school students in the Philadelphia public schools and convey the excitement of scientific research. Both Sinno and Crocker are increasingly active in various outreach activities at Penn and neighboring institutions and this project will provide additional materials for continuing these efforts.