Er3+ doped core-shell nanoparticles with large enhanced near-infrared luminescence for in vivo imaging

Abstract The second near-infrared (NIR-II) fluorescence probes presents many advantages for its large Stokes-shift and low signal to noise ratio. Lanthanide doped NIR-II luminescent nanoparticles have attracted intense attention in biomedical research. Here Er3+ doped nanoparticles with core–shell structure was proposed. After surface modification, we got PEG modified hydrophilic NaYbF4:Er@CaF2 nanoparticles. The cytotoxicity test and the imaging performance in vivo experiments were carried out. Under the irradiation of 980 nm laser, the mice presented clear near-infrared imaging in vivo. So far, prominent optical properties of NaYbF4:Er@CaF2-PEG UCNPs has been proved, which is expected to become a new type of imaging probe in the future.