Iron-oxide magnetic nanoparticles (MNPs) with tuned magnetic properties can enable novel diagnostic and therapeutic technologies such as magnetic particle imaging and hyperthermia. In order to optimize the magnetic properties of MNPs, organic synthesis methods are required. However, these organic synthesis methods render the nanoparticles hydrophobic and unusable for biomedical applications. To make MNPs functional in biomedical applications whilst retaining their magnetic functionality, they must be transferred to the aqueous phase using a biocompatible polymer. In this work, MNPs will be coated using a biocompatible PEG-ylated amphiphilic polymer: poly (maleic anhydride-alt-1-octadecene) or PMAO-PEG. To ensure the PMAO-PEG is a well suited polymer coating for MNPs, various molecular weights and molar ratios of PMAO-PEG are synthesized and characterized to study the effects of PEG surface density and molecular weight on MNPs. By altering the density of the polymer used to coat and phase transfer MNPs, effects such as the solubility, circulating life, colloidal stability, dosage frequency, and proteolytic degradation rates of MNPs in the biomedical applications are studied using data obtained from Gel Permeation Chromatography (GPC) and Fourier Transform Infrared Spectroscopy (FTIR). Molecular weight distributions of the various polymers are obtained from the GPC to evaluate the conjugation success after PEG-ylation. In addition, FTIR was used to identify known and unknown materials in the samples, determine the quality and consistency of samples, and to determine the amount of components in samples.

Nanoimprint lithography (NIL) has become a widely used technique in fabricating nanoparticles using a top-down approach with several advantages over bottom-up chemical methods, including being able to precisely control particle shape, size, structure, and composition. Using NIL, synthetic antiferromagnetic (SAF) nanoparticles can be fabricated using multilayer deposition techniques, imprinting, liftoff, and particle release into water with limited defects. The particles can also be coated with a functional polymer so that they can be used in a number of drug delivery systems. However, common NIL techniques often make it difficult to add functional coatings to the particles after the particles are released in water. Deposition methods for different layers, as well as using silicon molds that introduce defects and irregularity in particle size are other pitfalls that can be corrected using a new approach. The nanoparticles (~300 nm diameter) were homogeneously patterned using a mold to etch disk-shaped nanoparticles on a silicon substrate with layers of titanium and magnetite deposited on its surface via magnetron sputtering to contribute to the antiferromagnetic properties of the particles.  The fabrication process is extensive and utilizes many clean room processes, including nanoimprinting, dry etching, undercutting, multilayer deposition, liftoff, and polymer coating, though polymerization was not explored in this study.  Following, release techniques were used to produce a monodisperse and homogeneously-sized sample of high moment, multilayer particles in water with high saturation magnetization and low toxicity. Final results to determine the effectiveness of the particles were determined by studying the magnetic properties of the nanoparticle solution sample in the presence of an external magnetic field. With antiferromagnetic and useful imaging properties, functional biomagnetics could become a highly useful material system. Future work in this field includes biofunctionalizing the particles to modify in-solution behavior and implementing them into various biomedical systems, depending on how small the particles can be made using NIL.