Magnetic Nanowires for MRI Contrast, Cell Separation, Remote Magnetic Heating, and Collagen Hydrogels

Abstract

Magnetic nanoparticles of various shapes, sizes and compositions have proven useful tools for nanomedicine in recent years. Magnetic nanowires (NWs) fabricated by template electrodeposition have tunable diameters (tens to hundreds of nm) and lengths (nm to tens of microns). High magnetization metals and alloys, such as Ni, Co, Fe, and CoFe, can be electrodeposited; multiple layers of non-magnetic metals, such as Au or Cu, can be added to make multilayer NWs. Because of their high aspect ratios, the NWs have a large surface area, with inherent shape and magnetic anisotropy, so they are easy to manipulate or align by an external magnetic field. Each of these factors gives NWs an advantage over isotropic magnetic nanoparticles, for certain applications. In addition, the surface of the NWs may be functionalized for biocompatibility or to target specific biological applications. This thesis investigates using magnetic NWs for magnetic resonance imaging (MRI) contrast, remote heating by magnetic hysteresis, cell separation with external fields, and aligning collagen hydrogels with an external field. This research has analyzed important engineering questions regarding the design and synthesis of the NWs, including shape, size, composition, magnetic properties, surface functionalization, and nanoparticle aggregation. The NWs were compared against the current state-of-art nanoparticles for these applications, to demonstrate feasibility, highlight successes, analyze drawbacks, and discuss a path forward for improvement and implementation.