Enhanced luminescence of CaMoO₄:Eu by core@shell formation and its hyperthermia study after hybrid formation with Fe₃O₄: cytotoxicity assessment on human liver cancer cells and mesenchymal stem cells.

Highly water dispersible Eu³⁺ doped CaMoO₄ nanoparticles (core) covered by CaMoO₄ (shell) have been prepared using the polyol method. Significant enhancement in luminescence intensity by core@shell formation is observed due to the decrease of non-radiative rate arising from surface/defect of particles. Effect of 266 nm laser excitation (Mo-O charge transfer band) on the asymmetric ratio (A₂₁ = intensity ratio of electric to magnetic dipole transitions) has been studied and compared with a xenon lamp source. Luminescence intensity increases with the increase of power at 532 nm laser excitation. In order to explore materials, which can show dual functionalities such as luminescence as well as magnetic properties (magnetization of ∼14.2 emu g⁻¹), water dispersible Fe₃O₄-CaMoO₄:Eu hybrid magnetic nanoparticles (MN) have been prepared. This shows good heating ability up to ∼42 °C (hyperthermia) and luminescence in the red region (∼612 nm), which is in a biological window (optical imaging). Biocompatibility of the synthesized Fe₃O₄-CaMoO₄:Eu hybrid magnetic nanoparticles has been evaluated in vitro by assessing their cytotoxicity on human liver cancer cells (HepG2 cells) and hTERT cells using the MTT assay and fluorescent microscopy studies.