Europium-phenolic network coated BaGdF5 nanocomposites for tri-modal computed tomography/magnetic resonance/luminescence imaging

Abstract Multifunctional nanocomposites based on BaGdF 5 nanoparticles (NPs) and metal phenolic network (MPN) have been engineered as novel contrast agents for potential applications in X-ray computed tomography, magnetic resonance and luminescence imaging. The BaGdF 5 @MPN nanocomposites were synthesized at room temperature by coating BaGdF 5 NPs with europium-phenolic network, which was obtained by the coordination of europium (III) with tannic acid (TA). The in vitro cytotoxicity assays against HepG2 cells revealed that the BaGdF 5 @MPN nanocomposites presented better cytocompatibility and lower cytotoxity than pure BaGdF 5 NPs. In addition, vivid red and green luminescence can be observed by confocal laser scanning microscope (CLSM) from the BaGdF 5 @MPN nanocomposites laden HepG2 cells under the excitation of UV (390 nm) and visible light (440 nm), respectively. The longitudinal relaxivity value (r 1 ) of the nanocomposites was 2.457 mM −1 s −1 . Moreover, the nanocomoposites exhibited X-ray computed tomography (CT) and T 1 -weighted magnetic resonance (MR) imaging capacities, and the intensities of the enhanced signals of in vitro CT and MR images were proportional to the concentrations of the nanocomposites. These results indicated that the as-prepared BaGdF 5 @MPN nanocomposites are promising contrast agents for CT/MR/luminescence imaging. Graphical Abstract