| This dissertation describes the design and synthesis of hybrid magnetic particles with diameters in the nanometer and micrometer size regime. These hybrid particles exhibit multifunctional behavior that renders them attractive for use in selected biomedical applications. Most of the particles described herein possess core-shell structures that can be classified into four general categories based on their composition.;In the second category, composite nanoparticles that consist of silica-coated magnetic spheres encapsulated within thermo-responsive PNIPAM-co-AA hydrogels are fabricated and characterized.;In the third category, the hydrogel/silica-coated nanoparticles are further modified via the assembly of gold nanorods on their surfaces. The responses of these composite nanoparticles upon exposure to a variety of external stimuli (i.e., temperature, pH, and magnetic field) are examined and compared to the corresponding particles having no pendant nanorods. Owing to their multifunctional and multi-responsive nature, these magnetic hybrid composites offer a new paradigm in controlled drug delivery and nanotherapeutics.;In the fourth and final category, magnetic core particles encapsulated by a silica layer that contains covalently-embedded organic dyes are prepared and characterized. Potential uses of these composite nanoparticles as bimodal contrast agents and therapeutic entities are demonstrated.;In the first category, the combination of a magnetic core particle with silica and gold shells are successfully prepared with three distinct structural architectures. Structure 1 consists of spherical magnetic cores coated with a dielectric silica shell. Structure 2 comprises a linear or mostly linear chain of spherical magnetic particles stabilized with a continuous dielectric silica shell. Structure 3 consists of nanoparticles of type 1 coated with a gold shell. Notably, these unique magnetic structures offer multiple advantages over existing magnetic materials, with applications ranging from medical diagnostics to high-density data storage. |
