Rare-earth-doped and codoped y₂O₃ nanomaterials as potential bioimaging probes

The synthesis and characterization of various rare-earth (RE)-doped and codoped yttrium oxide (Y₂O₃) nanomaterials were undertaken in the current work. RE dopants such as terbium (Tb), europium (Eu), and erbium (Er) were successfully doped, and ytterbium (Yb)-Er was codoped into Y ₂O₃ nanomaterials. The as-synthesized nanomaterials are highly dispersed in the organic phase. X-ray diffraction peaks can be assigned to cubic Y₂O₃, which confirms the crystallinity of the as-prepared Y₂O₃ samples. Room temperature photoluminescence (PL) spectra showed characteristic emission peaks of Tb-, Eu-, and Er-doped Y₂O₃ samples. Up-conversion spectra of green and red emissions were also shown for Er-Yb-codoped Y₂O₃ samples. It was found that the intensities of the green and red emissions could be altered by varying the dopant concentration. The nanocrystals were surface-functionalized with an amine (NH₂) group via a reverse microemulsion method. The amine groups render the nanocrystals water-soluble and also afford them with the possibility of further functionalization by other biomolecules. in vitro cytotoxicity studies showed that the synthesized nanocrystals have no appreciable toxicity on human hepatocellular carcinoma (Hep-G2) cells at concentrations of 0.007-0.063 mg/mL. Because of the Y ₂O₃:RE nanomaterials' well-dispersity in water, low toxicity, and good PL, they can potentially be used as fluorophores in bioimaging.