Magneto-Optical Properties of Iron Oxide Nanoparticles for Use in Medical Imaging

Due to their non-toxic and magnetic nature, magnetite iron oxide (Fe3O4) nanoparticles have potential uses in biomedical applications such as for MRI contrast agents. In this work, the physical properties of rare-earth element doped (Tb and Eu) and undoped iron oxide nanoparticles were optically investigated. Absorption and photoluminescence (PL) from doped and undoped iron oxide nanoparticles in solution showed a well-defined excitonic absorption and weak PL. When the nanoparticles were drop cast into thin films, the absorption spectra remained unchanged while the PL disappeared, suggesting the thin film created non-radiative relaxation pathways. The magnetic properties of the excitons were examined using magnetic circular dichroism (MCD), which is a measure of the difference in absorption under left and right circularly polarized light. Temperature- and field-dependent MCD was used to determine the effect of Tb and Eu dopants on the Fe3O4 excitons. To further characterize optical properties of Fe3O4 nanoparticles and other materials, a spectrofluorometer was reconstructed for absorption and PL measurements. This consisted of wiring and controlling three motors to adjust the slit width and rotate a double monochromator using a microcontroller interface. The double monochromator was then calibrated and made available for optical measurements using a white light source.