Synthesis and characterization of magnetic nanorings for neuronal stimulation

Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.Cataloged from PDF version of thesis.Includes bibliographical references (pages 32-33).Magnetic nanorings (MNRs) are anisotropic nanomaterials that can support a magnetic vortex state, which can yield both colloidal stability and large hysteretic power losses when exposed to an alternating magnetic field (AMF). Coupled with the biocompatibility of polymer surface coatings, MNRs have the potential of being used for many biological applications, including neuronal stimulation, drug delivery, and cancer hyperthermia. In this work, we synthesized varying geometries of MNRs via a thermal decomposition route and characterize their structural, chemical, and magnetothermal properties. Scanning and transmission electron microscopy was used to analyze surface morphology and geometry of nanostructures. X-ray diffraction allowed for differentiation of paramagnetic and ferrimagentic phases of synthesized iron oxide. Vibrating scanning magnetometry and induced coupled plasma atomic emission spectroscopy were used to determine magnetic properties, including saturation magnetization (Ms) and coercive field (He). Finally, calorimetric measurements were performed to calculate specific power losses (SLPs) of varying compositions of MNRs. We demonstrate that MNRs exhibit hysteretic power loss and can be optimized for neuronal stimulation under biologically safe AMF conditions.by Francisco J. Garcia.S.B