Core@shell Fe 3 O 4 @Mn 2+ -doped NaYF 4 :Yb/Tm nanoparticles for triple-modality T 1 /T 2 -weighted MRI and NIR-to-NIR upconversion luminescence imaging agents

Core@shell structures of Fe 3 O 4 @Mn 2+ -doped NaYF 4 :Yb/Tm nanoparticles (NPs) were prepared and then used for in vivo NIR to NIR (980 nm to 800 nm) imaging, and as dual-mode T 1 / T 2 -weighted MRI because of the co-existence of Fe 3 O 4 and Mn 2+ in the NPs.