High Throughput Preparation of Tuneable Magnetically Assembled 1D Nanostructures

技术进步的发展在不断增长的纳米技术市场中非常重要，该市场将在未来五年内超过1250亿美元。1-一维（1D）纳米结构（其具有纳米级（<100 nm）范围之外的一个维度）通常是纳米线、纳米纤维和纳米管，并且由于它们在从电池到生物医学的范围内的领域中的应用而占据了该快速增长市场的显著部分。近年来，磁性一维材料变得特别流行，因为它们的大纵横比和一维结构引起各向异性，这可以产生定向的电子和离子输运以及不寻常的各向异性光学和磁性。由于这些性质，磁性一维材料已在磁记录、锂离子电池、传感器、催化和医学中得到应用。这种一维材料在许多应用中可以胜过它们的纳米颗粒（或0维，0 D）对应物，例如在医学中，其中各向异性导致增加的磁化强度和局部磁场强度。这为磁共振成像（MRI）等医学成像技术提供了更好的性能，其中1D材料由于其1D结构的各向异性增加，与其0 D类似物相比提高了信号增强。因此，已经开创和开发了许多用于1D材料的新制造技术，包括模板化、自下而上生长、光刻、静电纺丝和颗粒组装，尽管这些通常遭受所得结构的差的调谐性，并且因此遭受性能，以及可扩展性的挑战-这些问题对于它们的长期使用和工业吸收至关重要。长期以来，磁相互作用一直被用来产生容易对磁场做出响应的胶体结构，其中铁磁流体是最知名的例子。最近已经探索了使用磁性组装方法制备永久1D材料，其中磁性纳米颗粒的簇在合成期间或通过磁刺激纳米颗粒组装而组装成纳米线或纳米管的永久阵列。虽然成功地形成了一维纳米结构，但这些方法在控制所得材料的尺寸、纵横比和表面化学方面存在困难。因此，显然需要一种能够以高尺度可再现地制造具有受控和可调谐的纵横比、尺寸和表面的磁性1D纳米结构的技术。在这项提案中，我们的目标是通过利用连续流技术与磁性组装相结合来生产具有各种涂层的核-壳1D纳米结构材料来实现这一目标，这些材料可以轻松地进行修改以用于许多不同的应用。本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涂层剂的影响，以形成性能可调和可重复的一维材料库。通过这种方式，我们将开发一种新颖的、高通量的磁性一维纳米材料方法，该方法将对结构、纵横比、除了流体流动系统带来的可扩展性的好处之外，还可以改善1D材料的表面和由此产生的性能。作为案例研究，将测试所生产的材料作为磁共振成像（MRI）造影剂的性能。使用最先进的磁共振成像工具，性能的定量评估将证明可调1D材料在这一重要医疗应用中的优势。

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.