Small CaF2 nanocrystals as nano-sized tracers for in vivo 19F-MRI

In this study we present a novel class of ¹⁹F-nanoformulations based on small (<10 nm) fluoride-nanocrystals (specifically CaF₂ nanofluorides) for MRI applications. We show that homonuclear dipolar interactions can be averaged out by the fast tumbling of the PEG-coated nanocrystals thus enabling the acquisition of high-resolution ¹⁹F-NMR. Using this feature, we demonstrate that our newly developed nanofluorides could be used as ¹⁹F-MRI tracers and present a “hot-spot” mapping in an animal model inflammation. The proposed nanofluorides combine the advantages of using nanocrystals (small, high ¹⁹F-equivalency, maximal ¹⁹F-density, and surface modifiability) with the merits of ¹⁹F-MRI tracers.