Y2O3:Tm,Yb nanophosphors for correlative upconversion luminescence and cathodoluminescence imaging.

We present a phosphor nanoparticle that shows both upconversion luminescence (UCL) and cathodoluminescence (CL). With this particle, low-autofluorescence, deep-tissue and wide-field fluorescence imaging can be achieved with nanometer-order high-spatial-resolution imaging. We synthesized Y2O3:Tm,Yb nanophosphors that emit visible and near-infrared UCL under 980 nm irradiation and blue CL via electron beam excitation. The phosphors were applied to fluorescent imaging of HeLa cells. The photostability of the phosphors was superior to that of a conventional organic dye. We show that after uptake by HeLa cells, the particles can be imaged with SEM and CL contrast in a cellular section. This indicates that correlative UCL and CL imaging of biological samples could be realized.