R2 Enhancement by Formation of a Tungsten-Iron Alloy Crystal in the Apoferritin Cavity

Veronica Clavijo Jordan¹, Kevin M. Bennett¹

Nanoparticles have been developed as T₂ contrast agents for molecular MRI. However, there is still a need to develop agents with higher relaxivities in order to increase sensitivity to delivered agents in vivo. In this work, we formed a tungsten-iron alloy in the interior cavitiy of apoferritin. The use of the protein to form a crystal core enhances the magnetic properties of the particle. The yield of the process when compared to magnetoferritin was enhanced by 200%. The W-Magnetoferritin nanoparticles had a per-iron and per-particle transverse relaxivity of 27,666mM^-1s^-1 and 433,651mM^-1s^-1 respectively, which is a ~10% increase over magnetoferritin nanoparticles.