Europium doped-double sodium bismuth molybdate nanoparticles as contrast agents for luminescence bioimaging and X-ray computed tomography

Abstract

A one-pot method for the synthesis of uniform Eu³⁺-doped NaBi(MoO₄)₂ nanoparticles with an ellipsoidal shape and tetragonal crystal structure functionalized with polyacrylic acid is reported for the first time in the literature. The method is based on a homogeneous precipitation reaction from solutions in an ethylene glycol/water medium containing appropriate bismuth, sodium, and molybdate precursors and polyacrylic acid. The luminescence properties (excitation and emission spectra and luminescence lifetime) of such nanoparticles are evaluated for different Eu³⁺ doping levels, finding an intense red emission for all synthesized samples. The X-ray attenuation properties of the nanoparticles have been also analyzed, which were found to be better than those of a commercially computed tomography contrast agent (iohexol). The dispersibility of the nanoparticles in a physiological medium was also analyzed, finding that they could be well dispersed in a 2-N-morpholinoethanesulfonic acid monohydrate medium (pH = 6.5). Finally, the cell viability of such a phosphor has been analyzed using MIA-PaCa-2 cells and its in vivo toxicity has been evaluated using the nematode Caenorhabditis elegans model finding no significant toxicity in both cases up to a nanoparticle concentration of 100 μg mL⁻¹, which is within the range required for most in vivo applications. The developed Eu³⁺-doped NaBi(MoO₄)₂ nanoparticles are, therefore, excellent candidates for their use as bimodal probes for luminescence imaging and X-ray computed tomography.