High Throughput Preparation of Tuneable Magnetically Assembled 1D Nanostructures

在不断增长的纳米技术市场中，技术进步的发展是重要的，该市场将在未来五年内超过1250亿美元。一维(1D)纳米结构在纳米尺度(100 Nm)范围之外具有一维，通常是纳米线、纳米纤维和纳米管，由于它们在从电池到生物医学等领域的应用，在这个快速增长的市场中占据了相当大的份额。磁性一维材料由于其大的长径比和一维结构引起的各向异性，可以产生定向的电子和离子输运以及特殊的各向异性的光学和磁性，近年来变得特别流行。由于这些特性，磁性一维材料在磁记录、锂离子电池、传感器、催化和医学方面得到了应用。这种1D材料可以在许多应用中超过它们的纳米颗粒(或0维，0D)对应物，例如在医学中，各向异性导致磁化强度和局部磁场强度的增加。这提高了磁共振成像(MRI)等医学成像技术的性能，与0D类似物相比，1D材料由于其1D结构的各向异性增加而提高了信号增强。因此，许多用于1D材料的新的制造技术已经被开拓和开发，包括模板、自下而上的生长、光刻、静电旋转和颗粒组装，尽管这些技术经常受到所得到的结构的可调性差的影响，从而导致性能，以及可伸缩性的挑战-这些问题对于它们的长期使用和工业应用至关重要。长期以来，磁性相互作用一直被用来产生容易对磁场做出反应的胶体结构，其中最著名的例子是磁流体。最近探索了使用磁性组装方法来制备永久一维材料，在合成过程中或通过磁刺激纳米颗粒组装，将磁性纳米颗粒簇组装成纳米线或纳米管的永久阵列。虽然这些方法成功地形成了一维纳米结构，但在控制所得到的材料的尺寸、长宽比和表面化学方面遇到了困难。因此，显然需要一种能够在高尺度上可重复地制造具有可控和可调长宽比、尺寸和表面的磁性一维纳米结构的技术。在这项提议中，我们的目标是通过利用连续流动技术结合磁性组装来生产具有各种涂层的核壳一维纳米结构材料，这些材料可以很容易地进行修饰，以满足多种不同的应用。这项工作将系统地探索流速、磁场强度和持续时间、磁性纳米颗粒构建块和各种包覆剂的影响，以形成性能可调和可重现的一维材料库。通过这种方式，我们将开发一种新的、高通量的磁性一维纳米材料，除了流体流动系统带来的可伸缩性的好处外，它还将对一维材料的结构、长宽比、表面和由此产生的性质进行精确控制。作为一个案例研究，生产的材料将在磁共振成像(MRI)中测试其作为造影剂的性能。使用最先进的磁共振成像工具，性能的定量评估将展示可调1D材料在这一重要医疗应用中的好处。

Development of technological advances is important in the continually growing nanotechnology market, which is set to exceed $125 billion within the next five years. 1-dimensional (1D) nanostructures, possessing one dimension outside the nanoscale (<100 nm) range, are typically nanowires, nanofibers and nanotubes, and occupy a significant portion of this fast-growing market due to their application in sectors ranging from batteries to biomedicine. Magnetic 1D materials have become particularly popular in recent years, as their large aspect ratio and 1D structure gives rise to anisotropy, which can produce orientated electronic and ionic transport and unusual anisotropic optical and magnetic properties. As a result of these properties, magnetic 1D materials have found application in magnetic recording, lithium ion batteries, sensors, catalysis and medicine. Such 1D materials can outperform their nanoparticle (or 0-dimensional, 0D) counterparts in many applications, for example in medicine, where anisotropy leads to increased magnetisation and local magnetic field strengths. This provides improved performance in medical imaging techniques such as magnetic resonance imaging (MRI), where 1D materials boost signal enhancement compared to their 0D analogues thanks to the increased anisotropy of their 1D structures. A number of new fabrication techniques for 1D materials have hence been pioneered and developed, including templating, bottom-up growth, lithography, electrospinning, and particle assembly, though these often suffer from poor tuneability of the resulting structures, and hence properties, as well as challenges with scalability - issues which are critical for their long-term use and industrial uptake. Magnetic interactions have long been used to generate colloidal structures which respond readily to a magnetic field, with ferrofluids being the most well-known example. The preparation of permanent 1D materials using magnetic assembly approaches has been explored recently, with clusters of magnetic nanoparticles being assembled into permanent arrays of nanowires or nanotubes either during synthesis, or through magnetically stimulated nanoparticle assembly. Although successfully forming 1D nanostructures, these approaches suffer from difficulties in controlling the resulting materials' size, aspect ratio and surface chemistry. There is, therefore, a clear need for a technique capable of reproducibly fabricating magnetic 1D nanostructures with controlled and tuneable aspect ratios, sizes and surfaces, at high scales. In this proposal, we aim to achieve this through the exploitation of continuous flow technology combined with magnetic assembly to produce core-shell 1D nanostructured materials with various coatings, which can be modified with ease for numerous different applications. This work will systematically explore the effect of flow rate, magnetic field strength and duration, magnetic nanoparticle building blocks and various coating agents in order to form a library of 1D materials whose properties are tuneable and reproducible.In this way, we will develop a novel, high throughput approach to magnetic 1D nanomaterials which will have precision control over structure, aspect ratio, surfaces and hence resulting properties of the 1D materials, in addition to the benefits of scalability that come with fluid flow systems. As a case study, the produced materials will be tested for their performance as contrast agents in magnetic resonance imaging (MRI). Using state-of-the-art magnetic resonance imaging tools, quantitative assessment of performance will demonstrate the benefits of tuneable 1D materials in this important medical application.