NER: Integrated Magnetic and Chemical Assembly Techniques for Building Nanoparticle Arrays

这个纳米级探索性研究（NER）项目旨在开发流体自组装策略（通过磁力和化学力），在透明衬底上构建金属纳米颗粒阵列，作为制造基于芯片的表面等离子体共振（SPR）生物传感器的低成本、高通量解决方案。这项工作采用的关键概念是，非磁性材料，如金纳米颗粒，可以在可磁化流体中进行操作，如铁磁流体（例如，浓缩了磁性纳米颗粒的流体）。当外场作用于流体时，金纳米颗粒相对于周围介质呈负磁化，并且由于偶极子-偶极子相互作用，金纳米颗粒将形成具有可调周期性的有序纳米颗粒构型。一旦组装成阵列，即使在冲洗铁磁流体之后，颗粒和衬底之间引发的化学反应也可以将阵列结构嵌入表面。智力上的优点在于研究一个相对未被探索的课题，即在磁性流体中操纵非磁性纳米颗粒。主要的智力挑战是开发自一致计算磁场的计算方法，由磁性纳米颗粒浓度梯度和与衬底的相互作用产生。该项目将鼓励本科生和研究生参与研究，并通过在更广泛的自组装和纳米操纵领域中定义的经典电学和磁学的新课程的开发。特别强调将从历史上的黑人学院和大学（HBCUs）或历史上的少数民族大学（hmu）以及通过杜克大学普拉特研究员计划招收本科生。

This Nanoscale Exploratory Research (NER) project aims to develop fluidic self-assembly strategies (via magnetic and chemical forces) to build arrays of metal nanoparticles on transparent substrates, serving as a low-cost, high-throughput solution for fabricating chip-based surface plasmon resonance (SPR) biosensors. The key concept employed in this work is that nonmagnetic materials, such as gold nanoparticles, can be manipulated inside a magnetizable fluid, such as ferrofluid (e.g. a fluid concentrated with magnetic nanoparticles). When an external field is applied to the fluid, the gold nanoparticles become negatively magnetized with respect to the surrounding medium, and as a result of dipole-dipole interactions, the gold nanoparticles will form well-ordered nanoparticle configurations with tunable periodicity. Once assembled into an array, chemical reactions initiated between the particle and substrate can embed the array structure on the surface even after rinsing of the ferrofluid. The intellectual merit lies in studying a relatively unexplored topic of manipulating nonmagnetic nanoparticles inside magnetic fluids. The major intellectual challenge is to develop computational methods for self-consistently calculating the magnetic field, resulting from magnetic nanoparticle concentration gradients and interactions with the substrate. The PI will encourage participation of undergraduate and graduate students in research as well as through the development of new courses in classical electricity and magnetism as defined in the context of the broader fields of self-assembly and nano-manipulation. Special emphasis will be placed on recruiting undergraduate students from a Historically Black College and University (HBCUs) or Historically Minority University (HMUs), and through the Duke University Pratt Fellows program.