Fabrication of luminescent TiO₂:Eu^{3 +} and ZrO₂:Tb^{3 +} encapsulated PLGA microparticles for bioimaging application with enhanced biocompatibility

Rare earth is of great interest because of their unique optical properties, especially the rich luminescent spectra. In this study, we developed a facile one-pot microwave-assisted synthesis of luminescent Eu^{3 +} doped TiO₂ nanoparticles and Tb^{3 +} doped ZrO₂ nanoparticles. As a result, the emitting centers (Eu^{3 +} and Tb^{3 +}) were all well dispersed in the amorphous host oxide materials, leading to high luminescence. The obtained TiO₂:Eu^{3 +} and ZrO₂:Tb^{3 +} nanoparticles were then encapsulated into PLGA microparticles for bio-applications. These luminescent microparticles were then proven to be highly stable, biocompatible and of low cytotoxicity. We successfully demonstrated the bioimaging of live cells using the red-luminescent TiO₂:Eu^{3 +} nanoparticles and green-luminescent ZrO₂:Tb^{3 +} nanoparticles embedded PLGA microparticles. The microwave-assisted synthetic methodology can be further developed to be general method to prepare oxide nanoparticles.