Effect of doping Mg2+, Mn2+ ions on luminescence and relaxation of Gd2O3:Tb3+ nanocrystals

Gd2O3: Tb3+ nanocrystal co-doped with Mg2+ and Mn2+ ions were prepared by polyol method. The size, morphology, structure, fluorescence and relaxation properties of the nanoparticles were characterized, and the biocompatibility of Gd2O3: Tb3+ nanoparticles was evaluated by MTT toxicity test. The results showed that the fluorescence emission intensity of Gd2O3: Tb3+ nanocrystals was the highest with the Mg2+ doping con-centration of 0.05 mmol, and the longitudinal relaxivity (r(1)) decreased with the increase of Mg2+ concentration, while the transverse relaxivity (r(2)) increased slightly. The fluorescence emission intensity of Gd2O3: Tb3+ nanoparticles were decreased after Mn2+ doping, whereas the longitudinal and transverse relaxivity were improved. The nanoparticles showed good biocompatibility with Gd concentration ranging from 0.05 and 0.2 mM. The results indicated that the synthesized Gd2O3: Tb3+ nanoparticles were expected to be used in fluorescenceMRI dual-mode biological detection.