Bismuth-doped cobalt ferrite Nanoparticles for MRI and CT Contrast Enhancement

Mark M. Bailey, Jeff Davis, Cindy Zeissler, Cindi Dennis, and Angela R. Hight Walker


Nanomaterials play a defining role in the development of advanced biomedical imaging contrast agents due to their unique, tunable physical properties.  One of the advantages offered by nanoparticle-based contrast media over traditional contrast media is the ability to integrate contrast moieties of complimentary imaging techniques into one deliverable agent.   By combining two different imaging modalities, one gains the advantages of both.   Additionally, when used as a pharmacokinetic model for drug-loaded nanoparticles, combined imaging nanoparticles could provide better resolution of in vivo nanoparticle distribution within the body, thus providing a better fundamental understanding of the pharmacokinetics of drug-loaded nanoparticles.  This study aims to develop bismuth-doped, cobalt ferrite nanoparticles for use as a combined MR/CT contrast agent using simple, aqueous-based synthesis, relying on the x-ray attenuation of bismuth and the para- and/or ferrimagnetism of the cobalt ferrite domains for x-ray and MRI contrast enhancement, respectively.   Amine-terminated nanoparticles were prepared by mixing appropriate ratios of Fe3+, Co2+ and Bi3+ ions in a high-pH solution containing cetrimonium bromide (CTAB), a tertiary amine-containing surfactant.  Nanoparticles were characterized using SEM, TEM, Raman and dynamic light scattering.  Energy-dispersive x-ray spectroscopy indicated the presence of iron, cobalt and bismuth.  The nanoparticles also exhibited magnetic behavior in the presence of a rare-earth magnet.  Other characterization methods include SQUID magnetometry measurements and x-ray attenuation measurements to determine the particles’ utility as a combined MRI/CT contrast agent.  Future work will also include MRI and CT phantom imaging.