Sub-10 nm Sr2LuF7:Yb/Er@Sr2GdF7@SrF2 Up-Conversion Nanocrystals for Up-Conversion Luminescence-Magnetic Resonance-Computed Tomography Trimodal Bioimaging

Herein, sub-10 nm core shell nanocrystals (NCs), which select Sr2LuF7:Yb/Er as core, Sr2GdF7 as middle shell, and SrF2 as an outermost shell, were synthesized by a seed-mediated growth process. The NCs possess good crystallinity, morphology, and up conversion luminescent properties. After modification by polyethylenimine branched (PEI), in vitro cell up-conversion imaging with low autofluorescence was realized. Due to the presence of Gd3+ ions, in vivo magnetic resonance (MR) imaging was also achieved with these designed NCs. More significantly, these special core shell NCs exhibited high contrast in in vivo X-ray computed tomography (CT) imaging because of their good X-ray absorption ability. These results indicate that the core shell up-conversion NCs can serve as promising contrast agents for up-conversion luminescence MR CT trimodal bioimaging.