PAA-capped GdF3 nanoplates as dual-mode MRI and CT contrast agents

Aiming at improving the sensitivity and accuracy of diagnosis, the combination of magnetic resonance imaging (MRI) and X-ray computed tomography (CT) in a single probe is in urgent need. Here, we report the development of polyacrylic acid (PAA)-capped GdF3 nanoplates (NPs) as novel MRI and CT dual-mode contrast agents (CAs) with high longitudinal relaxivity (r1) and large X-ray attenuation coefficient. Uniform GdF3 rhombic NPs were fabricated by controlling reaction conditions and introducing dopants. The average size of GdF3 NPs is (10.6 ± 1.1) nm in long diagonal, (7.0 ± 0.8) nm in short diagonal, and (4.2 ± 1.2) nm in thickness. Ligand-exchange treatment was performed to render the NPs water-dispersible. The r1 of PAA-capped GdF3 NPs (15.8 L/(mmol s)) is four times higher than that of clinically used Gd-DTPA. We suppose that the high r1 value originates from the construction of two-dimensional (2D) nanostructures, which endows nanocrystals with larger surface areas and longer rotational correlation time than those of sphere nanostructures with the same volume. The CT contrast enhancement ability of PAA-capped GdF3 NPs was evaluated in comparison with clinically used Iohexol. The above results suggest that the PAA-capped GdF3 NPs could serve as CAs for MRI and CT dual-mode imaging.