The present invention provides functionalized magnetic nanoparticlescomprising a functional group, which functionalized magnetic nanoparticlesexhibit differential binding to a tissue, including brain tissue, bone, andvascular tissues. The present invention further provides compositions,including pharmaceutical compositions, comprising a subject functionalizedmagnetic nanoparticle. The present invention further provides diagnostic andresearch methods involving use of subject functionalized magneticnanoparticles. The present invention further provides a magnetic resonanceimaging (MRI)-visible drug delivery system； as well as methods of synthesizingsame. The MRI-visible drug delivery system has applications in determining thedistribution of drugs using MRI, as well as tissue-specific drug delivery.
