Syntheses of iron oxide and other transition metal oxide nanoparticles, and their modifications for biomedical applications

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Date
2014-03-27
Authors
Yathindranath, Vinith
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Abstract
Superparamagnetic iron oxide (Fe3O4 and γ-Fe2O3) nanoparticles (IONPs) are of great in-terest as a diagnostic and/or therapeutic aid. Several IONPs with biocompatible polymer coatings have been approved for clinical use, as MRI contrast agents. IONPs conjugated to targeting ligands and therapeutic agents are being investigated for targeted drug deliv-ery applications. The superparamagnetic properties of IONPs are also helpful for magnetic field assisted localization to specific target sites and for in situ MRI applications. This thesis primarily focuses on the synthesis and surface modifications (with biocompatible polymers including dextran, poly(ethylene glycol) (PEG), dextran, poly(ethyl methacry-late) (PEMA), poly(hydroxyethyl methacrylate) (PHEMA), etc.) of IONPs. The IONPs were prepared following the classical co-precipitation method and a novel reduction-hydrolysis method. Initial studies used bovine serum albumin (BSA) to examine the ca-pabilities of polymer coated IONP to deliver a model protein therapeutic. Gel migration studies using BSA physisorbed onto polymer coated IONP under gradient magnetic field of an MRI showed that the IONPs had limited control in transporting the protein. Cova-lent linking of therapeutics to IONP core can improve the time window of formers con-trollability using magnetic field. To facilitate covalent conjugations, functional silane coated IONPs (with surface amino and carboxylic acid) were prepared as general precur-sors. The utility of silane coated IONPs for bioconjugations was demonstrated by cova-lently linking PEG diacid through surface amino groups and by linking of BSA through surface carboxylic acid groups. The biocompatibility of the IONPs synthesized following the novel reduction-hydrolysis method were assessed in vitro on cell culture models using toxicity assays. The versatile reduction-hydrolysis method was further extended, as a general method to prepare several early transition metal oxide NPs (manganese oxide (Mn3O4), cobalt oxide (Co3O4), nickel/nickel oxide (Ni/NiO), copper/copper oxide (Cu/Cu2O) and zinc oxide (ZnO) NPs), silica nanoparticles with surface IONPs, and iron/iron oxide nanosheets.
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Keywords
Iron oxide, Nanoparticles, Drug delivery, Surface modification, Surface coating, Nanotechnology, Biomedical, MRI, Magnetic targeting, Bioconjugation, Synthesis, Nanosheet, Metal, Metal oxide, Silica, Magnetic
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