Correlative Tools for in Situ Analysis of Single Nanoparticles and their Ligands

设计师金纳米粒子由分子壳包围的金属核组成。纳米颗粒生长的最新进展已经产生了复杂的星形形状，具有独特的物理特性，直径约为人类头发的1/100。虽然星状结构的形成与反应条件有关，但由于生长机制仍然未知，因此具有特定结构特征的颗粒的受控形成仍然是一个挑战。在化学系大分子，超分子和纳米化学项目的支持下，西北大学的Teri Odom教授正在开发一系列分析工具，以获得单个纳米颗粒在其天然生长环境中的更高结构和化学信息。使用这个工具包，奥多姆教授和她的学生正在确定纳米颗粒形成的关键中间体，这可以促进我们对复杂纳米结构如何生长的理解。该项目可以为创造具有特定形状的颗粒铺平道路，这些颗粒将对一系列技术产生广泛影响，包括个性化医疗和单分子污染物检测。该项目培养未来的科学家，外联工作的重点是开发一个新的通用化学序列，并制定研究生和初级教师培训计划。该项目还通过桤木天文馆的“纳米童子军日”等项目为未来的科学家提供培训机会。 奥多姆教授还积极外展到当地中学生针对少数民族学生。该提案旨在开发相关工具，以在近原位，单颗粒水平上研究金属纳米颗粒及其周围环境。这项工作将多种工具结合在一个综合策略中，以获取来自单个纳米颗粒的实时，统计和多功能信息。尽管使用金盐和Good缓冲液的无籽生长条件已显示出促进纳米颗粒中的不同曲率区域，这可以导致特定的、精致的宏观尺度性质，但对纳米颗粒形成关键的中间体的鉴定还不可能。为了确定纳米颗粒的形状及其配体分布如何与局部环境相互作用，需要高通量的单纳米颗粒统计数据。研究目标包括：（1）重新利用电子顺磁共振光谱，将不同自由基的产生与纳米颗粒中间体形状和最终产物相关联;（2）用宽场微分干涉对比光学显微镜观察单个纳米颗粒在生长期间的结构演变;和（3）用一种工具如时间-时间-时间曲线（time-of-time）绘制不同颗粒表面上的配体分布。该奖项反映了美国国家科学基金会的法定使命，并被认为是值得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的支持。

Designer gold nanoparticles consist of a metallic core surrounded by a molecular shell. Recent advances in nanoparticle growth have produced complicated star-like shapes that exhibit unique physical properties and are about 1/100 the diameter of a human hair. While the formation of the stellated structures is linked to the reaction conditions, controlled formation of particles with specific structural features remains a challenge since the growth mechanism is still unknown. With support from the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Teri Odom of Northwestern University is developing a series analytical tools to achieve higher structural and chemical information of single nanoparticles in their native growth environments. Using this toolkit, Professor Odom and her students are identifying key intermediates in nanoparticle formation that could advance our understanding of how complex nanostructures grow. The project could pave the way to create particles with specified shapes that would have broad implications for a range of technologies, including personalized medicine and single-molecule contaminant detection. The project trains future scientists, with outreach efforts focusing on developing a new general chemistry sequence and developing graduate and junior faculty training initiatives. The project also provides training opportunities for future scientists through programs such as 'Nano Scout Day' at the Alder Planetarium. Professor Odom also actively outreaches to local middle school students targeting underrepresented minority students. This proposal aims to develop correlative tools to study metal nanoparticles and their immediate surrounding environment at the near-in situ, single-particle level. The work combines multiple tools in an integrated strategy to access real-time, statistical, and multi-functional information from individual nanoparticles. Although seedless growth conditions using a gold salt and Good's buffers have been shown to promote distinct curvature regions in nanoparticles that can result in specific, exquisite macroscale properties, identification of intermediates key to nanoparticle formation has not yet been possible. To determine how nanoparticle shape and their ligand distribution interacts with local environments, high-throughput, single-nanoparticle statistical data is required. The research objectives include: (1) repurposing electron paramagnetic resonance spectroscopy to correlate the generation of different radicals with nanoparticle intermediate shapes and final products; (2) visualizing structural evolution of single nanoparticles during growth with wide-field differential interference contrast optical microscopy; and (3) mapping ligand distributions on different particle surfaces with one-of-a-kind tools such as time-of-flight secondary ion mass spectrometry using particle projectiles.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.