Synthesis and Characterization of Intrinsically Radiolabeled Lanthanide Phosphate Nanoparticles Toward Biomedical and Environmental Applications

Lanthanide phosphate nanomaterials are appealing as multifunctional platforms for biomedical applications because of their low toxicity, radiation resistance, and unique luminescence and magnetic properties. Lanthanide phosphate nanoparticles (NPs) radiolabeled with 156Eu were synthesized by an aqueous route using sodium tripolyphosphate as a phosphate source and complexing agent. GdPO4 was used as a host matrix, while synthetic concentrations of Ce3+/Tb3+ and Eu3+ were varied between 5–40% and 10–30%, respectively, and yielded spherical NPs with hexagonal crystal system and particle size < 5 nm. Luminescence emission and magnetic susceptibility were influenced by lanthanide concentrations where characteristic 5D0-7FJ and 5D4-7FJ transitions were observed for Eu3+- and Tb3+-doped NPs, respectively. Chemical yield of > 90% was achieved for GdPO4 and Gd0.6Ce0.3Tb0.1PO4 NPs intrinsically radiolabeled with 156Eu. In vitro retention of 156Eu within LnPO4 NPs was > 97% over 3 weeks. Intrinsically radiolabeled LnPO4 NPs have the potential to combine the luminescence and magnetic properties of Ln3+ ions with lanthanide radioisotopes for biomedical and environmental applications.