Abstract
The aim of this study is to fabricate a hybrid composite of iron (Fe) core-carbon (C) shell nanoparticles with enhanced magnetic properties for contrast enhancement in magnetic resonance imaging (MRI). These new classes of magnetic core-shell nanoparticles are synthesized using a one-step top-down approach through the electric plasma discharge generated in the cavitation field in organic solvents by an ultrasonic horn. Transmission electron microscopy (TEM) observations revealed the core-shell nanoparticles with 10-85 nm in diameter with excellent dispersibility in water without any agglomeration. TEM showed the structural confirmation of Fe nanoparticles with body centered cubic (bcc) crystal structure. Magnetic multi-functional hybrid composites of Fe core-C shell nanoparticles were then evaluated as negative MRI contrast agents, displaying remarkably high transverse relaxivity (r&sub2;) of 70 mM-1·S-1 at 7 T. This simple one-step synthesis procedure is highly versatile and produces desired nanoparticles with high efficacy as MRI contrast agents and potential utility in other biomedical applications.