Tb-doped iron oxide: Bifunctional fluorescent and magnetic nanocrystals

A new class of fluorescent and superparamagnetic bifunctional nanocrystal has been successfully prepared by a facile, non-hydrolytic method. The synthesized Tb-doped γ-Fe₂O₃ nanocrystals are highly monodispersed with a diameter of 13 nm, show superparamagnetic behaviour with saturation magnetism strength of 30 emu g^-1, and exhibit photoluminescence at room temperature. The nanocrystals are amine-functionalized to render them water-dispersible and ease of further functionalization by other biomolecules. In vitro cytotoxicity tests indicate that these nanocrystals are non-toxic. Nanocrystals of such bifunctionality are envisioned to have potential as probes in integrated imaging technique, of which at least two imaging modalities (for example magnetic resonance imaging (MRI) and fluorescence microscopy) are combined to provide enhanced visualization at tissues and cellular levels.