High Throughput Preparation of Tuneable Magnetically Assembled 1D Nanostructures

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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.