Lanthanoid-Doped Phosphate/Vanadate Mixed Hollow Particles as Ratiometric Luminescent Sensors

Rare earth (RE) phosphates and vanadates are structurally similar compositions that display distinct but complementary luminescent properties. The properties of these phosphors can be combined in REPO₄-REVO₄ heterostructures during the development of new sensing technologies for biological applications. This work presents the synthesis of hollow RE phosphate/vanadate colloidal particles and evaluates their applicability as luminescent markers. Hydrothermal treatments of RE hydroxycarbonate particles in the presence of the PO₄^3- and VO₄^3- precursors afforded the final REPO₄-REVO₄ solids in a two-step template synthesis. We converted precursor hydroxycarbonate particles into the final heterostructures and characterized their structure and morphology. According to our detailed study into the spectroscopic properties of Eu³⁺-doped particles and their luminescence response to several species, the presence of the phosphate and vanadate phases in a single particle provided different chemical environments and enabled the design of a ratiometric approach to detect H₂O₂. These results open new perspectives for the development of new intracellular luminescent markers.