SGER: Development of NMR relaxation theory for colloidal aggregates of superparamagnetic nanoparticles

非技术描述：超顺磁性氧化铁纳米颗粒（SPIO）正在开发作为MRI造影剂，以检测癌症和动脉粥样硬化等疾病。 这些聚集胶体陶瓷纳米颗粒的系统对于医学界用于体内传感和成像以及体外诊断特别感兴趣。 这些传感器通过在感兴趣的化学物质存在的情况下聚集在一起来工作。 缺乏一致的理论来描述这些传感器的操作，阻碍了这些应用的发展。 该项目旨在开发这样一种理论，并创建一个框架，用于设计SPIO传感器，以获得最佳和可靠的性能。 理论工作将得到实验的支持，以探索纳米粒子的性质。 常规技术不具有执行必要数量的测量以使理论的发展切实可行的能力。 一个定制的一种仪器，每天能够进行数千次测量，将用于提供数据和实验验证理论。 该项目将培训一名研究生。技术规格：拟议的研究将通过提供工程超顺磁性纳米颗粒的科学基础，实现基于聚集的测定或成像方式。 挑战包括实现特异性，更高的信噪比和颗粒优化（核心组成和大小，配体密度等）。 目前还没有设计规则来指导化学家在最佳聚集状态下实现高灵敏度和稳定性。 这项研究将使医学诊断和体内成像的创新成为可能。目前对聚集建模的尝试使用为未聚集颗粒开发的经验理论。 分形聚集体被表示为一个单一的大颗粒上的外球扩散理论。 这种方法忽略了水分子进入聚集体内部的能力，只适用于很窄的条件范围。 计算机模拟正在开发，占分形聚集体内的水的扩散，并解决在较高的拉莫尔频率观察到的差异。正在开发不同尺寸和聚集体构型的SPIO纳米颗粒，为理论模型提供数据。 传统的NMR弛豫仪不适合进行全面研究所需的高通量测量。 一个定制的高通量核磁共振弛豫仪正在被用来帮助制定一个新的理论。 该仪器能够快速有效地研究数百个参数。

NON-TECHNICAL DESCRIPTION: Superparamagnetic iron oxide nanoparticles (SPIO) are being developed as MRI contrast agents to detect diseases such as cancer and atherosclerosis. These systems of aggregating colloidal ceramic nanoparticles are of particular interest to the medical community for in vivo sensing and imaging, and in vitro diagnostics. The sensors operate by clumping together in the presence of the chemical of interest. A lack of a consistent theory describing the operation of these sensors hinders the advancement of these applications. This project aims to develop such a theory and to create a framework for engineering the SPIO sensors for optimal and reliable performance. The theoretical work will be supported experiments to explore nanoparticle properties. Conventional techniques do not have the capabilities to perform the necessary number of measurements to make the development of the theory practicable. A custom-built one of a kind instrument that is capable of thousands of measurements a day will be used to provide data for and experimentally verify the theory. This project will involve training of one graduate student. TECHNICAL DETAILS: The proposed research will enable aggregation based assays or imaging modalities by providing the scientific basis to engineer superparamagnetic nanoparticles. Challenges include achieving specificity, higher signal to noise, and particle optimization (core composition and size, ligand density, etc.). There are as yet no design rules to guide the chemist on the best aggregation state to achieve high sensitivity and stability. This research will enable innovation in medical diagnostics and in vivo imaging.Current attempts at modeling aggregation use empirical theories developed for unaggregated particles. The fractal aggregates are represented as a single large particle on which the outer sphere diffusion theory is applied. This approach ignores the water molecules' ability to access the inner parts of the aggregate and only applies over a narrow range of conditions. Computer simulations are being developed that account for the diffusion of water within the fractal aggregate and address the discrepancy observed at higher Larmor frequencies. SPIO nanoparticles of different size and aggregate configuration are being developed to provide data for the theoretical model. Conventional NMR relaxometers do not lend themselves to high-throughput measurements required for a comprehensive study. A custom-built high-throughput NMR relaxometer is being used to aid the formulation of a new theory. The instrument enables hundred of parameters to be investigated quickly and efficiently.