Yb-Based Nanoparticles with the Same Excitation and Emission Wavelength for Sensitive in Vivo Biodetection.

Near-infrared luminescent emission has been widely used as a signal for biological detection with its high spatial resolution and fast response. Rare-earthdoped nanoparticle-dye composites have diverse advantages of a wide operation wavelength and remarkable light stability, while the application is limited by the low luminescence quantum yield of rare-earth nanoparticles. Hence, in this work, we use a singly Yb doped nanoparticle that has strong luminescence emission at 975 nm under excitation at the same wavelength as an energy donor to construct the detection system. An inner filter pair, composed of core-shell nanophosphor NaYF4/20%Yb@NaYF4 (1:2) nanocrystals (csYb) as a luminescent beacon and ClO--responsive cyanine dye Cy890 as a filtering agent, was designed as a model. With a time-gated detection mode, the nanocomposites realize the detection limit at 0.55 ppb as demonstrated in a ClO- detection trial. The csYb&Cy890 nanocomposites can also monitor ClO- by luminescence signals in both living cells and mice models.