Multifunctional gadolinium-labeled silica-coated Fe3O4 and CuInS2 nanoparticles as a platform for in vivo tri-modality magnetic resonance and fluorescence imaging.

The facile fabrication of Gd-labeled superparamagnetic Fe3O4 nanoparticles (NPs) and fluorescent CuInS2 (CIS) quantum dots conjugated with arginine-glycine-aspartic acid (RGD) peptides has been demonstrated, for tri-mode targeted T1-, T2-weighted magnetic resonance (MR) and fluorescence imaging of pancreatic cancer. The core-shell nanocomposites formed are water-dispersible, stable and biocompatible, as confirmed by MTT assay on BXPC-3 cells. Relaxivity measurements show a T1 relaxivity (r1) of 1.56 mM-1 s-1 and a T2 relaxivity (r2) of 23.22 mM-1 s-1, which enable T1- and T2-weighted MR imaging of cancer cells in vitro and in vivo. The MR imaging data clearly indicate that the multifunctional NPs can specifically target cancer cells with αvβ3 integrin over-expression on the cell surface, through a receptor-mediated delivery pathway. The T1-weighted positive and T2-weighted negative enhancement in the MR imaging significantly improves the diagnosis accuracy, and fluorescence imaging of tumor tissue can assist in clinical surgery. These findings suggest that these multifunctional NPs could be used as a platform for bimodal imaging (both MR and fluorescence) in various biological systems.