Fe 3 O 4 @SiO 2 @Au nanoparticles for MRI-guided chemo/NIR photothermal therapy of cancer cells.

Novel functionalized (biofunctionalization followed by cisplatin immobilization) Fe 3 O 4 @SiO 2 @Au nanoparticles (NPs) were designed. The encapsulation of Fe 3 O 4 cores inside continuous SiO 2 shells preserves their initial structure and strong magnetic properties, while the shell surface can be decorated by small Au NPs, and then cisplatin (cPt) can be successfully immobilized on their surface. The fabricated NPs exhibit very strong T 2 contrasting properties for magnetic resonance imaging (MRI). The functionalized Fe 3 O 4 @SiO 2 @Au NPs are tested for a potential application in photothermal cancer therapy, which is simulated by irradiation of two colon cancer cell lines (SW480 and SW620) with a laser ( λ = 808 nm, W = 100 mW cm -2 ). It is found that the functionalized NPs possess low toxicity towards cancer cells (∼10-15%), which however could be drastically increased by laser irradiation, leading to a mortality of the cells of ∼43-50%. This increase of the cytotoxic properties of the Fe 3 O 4 @SiO 2 @Au NPs, due to the synergic effect between the presence of cPt plus Au NPs and laser irradiation, makes these NPs perspective agents for potential (MRI)-guided stimulated chemo-photothermal treatment of cancer.