GdVO₄:Eu³⁺,Bi³⁺ Nanoparticles as a Contrast Agent for MRI and Luminescence Bioimaging

Abstract

With the development of multifunctional imaging, gadolinium (Gd)-bearing inorganic nanoparticles (NPs), which were doped with trivalent lanthanide (Ln3+), have been applied in magnetic resonance imaging (MRI) and optical imaging owing to their high payload of Gd3+ ions and specific optical characteristics. In this study, we chose GdVO4 codoped with Eu3+ and Bi3+ as the host material to generate a highly efficient contrast agent (CA) for MRI and long-term luminescence imaging. The new CA emits strong and stable luminescence because of its strong characteristic emissions, resulting from the energy-transfer process from the vanadate groups (VO43–) to the Eu3+ and Bi3+ dopants. Additionally, these NPs provided conspicuous T1 and T2 relaxation time-shortening characteristics, which result in MRI enhancement. GdVO4:Eu3+,Bi3+ NPs were tested on liver tumor-bearing nude mice, and showed improved liver tumor contrast in T2-weighted MR images (T2WI). The dual-modal imaging probe exhibited no cytotoxicity or organ toxicity, reflecting its excellent biocompatibility. Thus, GdVO4:Eu3+,Bi3+ has the potential to be used for bioassays in vitro and liver tumor targeting in vivo. The results reveal the great promise of using the designed GdVO4:Eu3+,Bi3+ NPs as luminescent and MRI dual-mode bioprobes for clinical bioimaging applications.