Bifunctional Tm,Yb:GdVO@SiO Core-Shell Nanoparticles in HeLa Cells: Upconversion Luminescence Nanothermometry in the First Biological Window and Biolabelling in the Visible.

The bifunctional possibilities of Tm,Yb:GdVO@SiO core-shell nanoparticles for temperature sensing by using the near-infrared (NIR)-excited upconversion emissions in the first biological window, and biolabeling through the visible emissions they generate, were investigated. The two emission lines located at 700 and 800 nm, that arise from the thermally coupled F and H energy levels of Tm, were used to develop a luminescent thermometer, operating through the Fluorescence Intensity Ratio () technique, with a very high thermal relative sensitivity . Moreover, since the inert shell surrounding the luminescent active core allows for dispersal of the nanoparticles in water and biological compatible fluids, we investigated the penetration depth that can be realized in biological tissues with their emissions in the NIR range, achieving a value of 0.