Mesoporous silica coating NaYF4:Yb,Er@NaYF4 upconversion nanoparticles loaded with ruthenium(II) complex nanoparticles: Fluorometric sensing and cellular imaging of temperature by upconversion and of oxygen by downconversion.

Accurate detection of temperature and oxygen concentration at the cellular level is important in tumor diagnosis. Multifunctional nanocomposites are described that consist of upconversion luminescent nanoparticles capped with mesoporous silica and loaded with an oxygen-sensitive luminescent ruthenium complex. The nanocomposites of type NaYF4:Yb,Er@NaYF4@mSiO2-Ru have two modes of operation: Its red downconversion luminescence (at excitation/emission peaks of 455/606 nm) is quenched by oxygen (O2), and this is used to sense and image O2. The green upconversion luminescence (typically acquired at excitation/emission wavelengths of 980/525 and 544 nm), in turn, is used to measure temperature. The nanocomposites were then applied to dual mode in-vitro imaging of temperature and O2 in hepatocellular carcinoma cells (HepG-2). Graphical abstract A new multifunctional nanocomposite of mesoporous silica coating NaYF4:Yb,Er@NaYF4 upconversion nanopaticless loaded with ruthenium (II) complex has been designed with both green upconversion and red downconversion luminescence for temperature detection, oxygen sensing and dual mode cell imaging.