Monday, June 18, 2007
Golden Eagle Eyrie (Boise Centre on the Grove)

The Biomimetic synthesis of Magnetite for application in MRI using a novel Ferritin from the hyperthermophilic Archaeaon Pyrococcus furiosus

Mackenzie J. Parker, Brad Ramsay, Mark Allen, Michael Klem, Masaki Uchida, Trevor Douglas, Mark Young, and Yves Idzerda. Montana State University, Bozeman, MT

Protein encapsulated magnetic nanoparticles are expected to dramatically improve magnetic resonance imaging (MRI) because they are bio-compatible, minimizing harmful side effects and increasing contrast sensitivity as a dark field, T2 agent. We have developed new magnetic iron oxide nanoparticles that are encapsulated within a small, hyperthermophilic protein cage architecture. These protein cages have been shown to serve as excellent molds for the synthesis of nano-scale particles giving rise to very homogeneous properties. This work describes the use of ferritins, a family of proteins that naturally sequester iron (as a small particle of iron oxide) within their cage-like architecture. We have used a novel, thermally stable ferritin from the hyperthermophilic archaeaon Pyrococcus furiosus to synthesize magnetite (Fe3O4) nanoparticles at 65C and 85C. Dynamic light scattering, size exclusion chromatography, and transmission electron microscopy were used to characterize the protein-mineral composite and confirmed that mineral was contained within the protein cages. Alternating current magnetic susceptibility (ACMS) and vibrating sample magnetometry (VSM) were used to characterize the magnetic properties of the mineral cores. Results show that P. furiosus ferritin can withstand high temperatures and successfully direct the synthesis of magnetite within its hollow core. The magnetic nanoparticles formed at these elevated temperatures have roughly the same magnetic properties as those previously synthesized within mammalian ferritins, but show a distinct increase in magnetic saturation, suggesting a more ordered particle formation. We conclude that P. furiosus ferritin can serve as a platform for investigations of the effects of elevated temperature in the syntheses of bio-mimetic nanomaterials.