A new class of water-soluble, fluorescent, magnetic quantum dots-magnetoferritin bioconjugate-is prepared. The nanostructures are patterned mainly its dimer particles as characterized by high-angle annular dark-field scanning transmission electron microscopy and electron energy loss spectroscopy. Magnetic (high spontaneous magnetization values, superparamagnetism) and fluorescent (narrow emission peaks, uniform brightness) properties of both nanoblocks are maintained in the final nanostructure.