The present invention provides functionalized magnetic nanoparticles comprising a functional group, which functionalized magnetic nanoparticles exhibit differential binding to a tissue, including brain tissue, bone, and vascular tissues. The present invention further provides compositions, including pharmaceutical compositions, comprising a subject functionalized magnetic nanoparticle. The present invention further provides diagnostic and research methods involving use of subject functionalized magnetic nanoparticles. The present invention further provides a magnetic resonance imaging (MRI)-visible drug delivery system； as well as methods of synthesizing same. The MRI-visible drug delivery system has applications in determining the distribution of drugs using MRI, as well as tissue-specific drug delivery.
