Lanthanide-based nanocrystals as dual-modal probes for SPECT and X-ray CT imaging

Applications of lanthanide-based nanoparticles for bioimaging have attracted increasing attention. Herein, small size PEG-EuOF:Sm-153 nanocrystals (similar to 5 nm) (PEG = poly(ethylene glycol)bis(carboxy-methyl)ether) combined with the radioactive and X-ray absorption properties were synthesized. The distribution of the PEG-EuOF nanocrystals in living animals was studied by ex vivo radioassay, inductively coupled plasma-atomic emission spectrum (ICP-AES) analysis and in vivo SPECT imaging, which indicated that the small size PEG-EuOF:Sm-153 had long blood retention time (blood half-life (tip) reach to 4.65 h) and were eliminated significantly through biliary/gastrointestinal pathway in vivo. Meanwhile, benefiting from the high attenuation ability of Eu, the small size PEG-EuOF was successfully applied for lymph node CT imaging, extending the bio-applications of these small nanocrystals. The results of cytotoxicity and in vivo toxicity also showed that the PEG-EuOF nanocrystals have relatively low toxicity, which suggest their safety for in vivo imaging. The studies provide preliminary validation for the use of PEG-EuOF nanocrystals for in vivo bioimaging applications. (C) 2014 Elsevier Ltd. All rights reserved.