Europium-doped gadolinium sulfide nanoparticles as a dual-mode imaging agent for T1-weighted MR and photoluminescence imaging

We present a facile synthesis of europium-doped gadolinium sulfide (GdS:Eu3+) opto-magnetic nanoparticles (NPs) via sonochemistry. Their photoluminescence and strong paramagnetic properties enable these NPs to be utilized as an in vitro cell imaging and in vivo T1-weighted MR imaging probe. The GdS:Eu3+ NPs have a prominent longitudinal (r1) relaxivity value, which is a critical parameter for T1-weighted MR imaging. Here, we showed not only their strong positive contrast effect to blood vessels and organs of mice, but also blood half-life and biodistribution including clearance from organs, in order to assess the GdS:Eu3+ NPs as a competent nanocrystal-based T1 contrast agent. We further showed confocal images of breast cancer cells containing GdS:Eu3+ NPs to evaluate as a photoluminescence probe. Dual-mode imaging capability obtained from the GdS:Eu3+ NPs will allow target-oriented cellular imaging as well as the resulting disease-specific MR imaging.