X-Ray Excited Luminescence Spectroscopy and Imaging with NaGdF4:Eu and Tb

X-ray scintillating NaGdF₄: Eu and Tb nanophosphors were synthesized via co-precipitate and hydrothermal methods, encapsulated with silica, functionalized with biotin, and characterized by X-ray excited optical luminescence spectroscopy and imaging. The nanophosphors synthesized by co-precipitate method were ~90 and ~106 nm in size, respectively; nanophosphors synthesized by hydrothermal method showed the highest luminescence intensity. Further, we investigated the effect of thermal annealing/calcination on the X-ray excited luminescence spectra and intensity. We observed, at high-temperature, NaGdF₄: Eu@SiO₂ converts to NaGd₉Si₆O₂₆: Eu which is also an X-ray scintillator. The particles generate light through tissue and can be selectively excited using a focused X-ray source for imaging and light generation applications. The particles also act as MRI contrast agents for multi-modal localization.