Characterizations of lanthanide-doped nanoscintillators (NSs) and Rose Bengal (RB)-loaded NSs (RB-NSs). (a) TEM images of NaGdF4:Tb,Ce (core NSs) and NaGdF4:Tb,Ce@NaGdF4 (core/shell NSs). The insets show size distribution. Scale bar, 10 nm. (b) X-ray diffraction (XRD) patterns of core and core/shell NSs. (c) Room-temperature emission spectra of core and core/shell NSs under excitation at 254 nm. (d) Zeta-potentials of water-soluble NSs with different concentrations of RB. (e) Emission spectra of NS and RB-NSs under excitation at 254 nm. Inset: Emission spectrum of NSs (black) and RB (red), respectively. (f) Reactive oxygen generation (ROS) of RB-NSs under a single fraction X-ray irradiation (n=3, independent experiments). (g–i) (g) T1-weighted MR image and (h) r1 (1/T1) and (i) r2 (1/T2) relaxivity of RB-NSs as a function of Gd concentration from RB-NSs, measured using 7T MR scanner. Scale bar: 10 nm.