Hydrothermally synthesized lanthanide-incorporated multifunctional zirconia nanoparticles: Potential candidate for multimodal imaging

Enabled zirconium oxide Nanoparticles (NPs) are multifunctional nanoparticles that can be employed for multimodal imaging and can show good biocompatibility. In this work, we have synthesized Dysprosium (Dy) and Holmium (Ho) enabled zirconium oxide nanoparticles (DY/Ho-ZrO2 NPs) and have evaluated their potential as candidates for contrast agents in different imaging modalities such as X-ray computed tomography (CT), Photoluminescence (PL) imaging and Magnetic Resonance Imaging (MRI). Rare earth elements have large atomic numbers, and their incorporation can enhance the X-ray attenuation characteristics of their host along with their optical properties. Rare earth elements exhibit paramagnetic character which can be utilized for MRI contrast enhancement. A combination of these imaging modalities can fulfill the limitations faced while using a single imaging technique. Methods: We have successfully synthesized Dy and Ho incorporated zirconia nanoparticles (Dy/Ho-ZrO2) by a simple one-step hydrothermal method. Results: Prepared NPs were characterized for their physical properties. X-ray diffraction (XRD) revealed the crystalline phases present in Dy-ZrO2 and Ho-ZrO2 NPs with a crystallite size of 27 nm and 21.54 nm respectively. Scanning Electron Microscopy (SEM) results revealed the morphology of the nanoparticles, while EDS analysis gave the qualitative as well quantitative nature of synthesized nanocrystals. Photoluminescence (PL) data of Dy/Ho-Zirconia NPs have shown emission peaks near 419 nm when excited at 310 nm. Suspensions of prepared NPs with various concentrations were imaged on a CT machine in the clinical setting for contrast study. High CT contrast was observed for these NPs even at very low concentrations. Dysprosium doped sample was further evaluated for its potential as an MRI contrast agent. Dark cytotoxicity and photo-cytotoxicity results performed using Rhabdomyosarcoma (Rd) cancer cell lines revealed good biocompatibility of prepared NPs. Conclus