Solvothermal synthesis and characterization of ytterbium/iron mixed oxide nanoparticles with potential functionalities for applications as multiplatform contrast agent in medical image techniques

A solvothermal route to prepare Glutathione capped hybrid ytterbium/iron oxide nanoparticles with potential applications as multiplatform contrast agent in medical image techniques has been developed. The influence of ytterbium/iron molar ratio used as precursor, as well as the degree of the autoclave filling on the structural and morphological characteristics of the obtained nanoparticles has been extensively studied. Although all nanoparticles present similar composition, with YbFeO3 being the majority phase, size and morphology of the as synthetized nanoparticles are highly influenced by the critical temperature and by the over -saturation reached during the solvothermal process. We have demonstrated that glutathione properly functionalizes the hybrid nanoparticles, increasing their colloidal stability and decreasing their cytotoxicity. Additionally, they show good imaging in magnetic resonance and X-ray computerized tomography, thereby indicating promising potential as a dual contrast agent. This work presents, for the first time, glutathione functionalized ytterbium/iron oxide nanoparticles with potential applications in Biomedicine. © 2022 Elsevier Ltd and Techna Group S.r.l

Improving the Redox Response Stability of Ceria-Zirconia Nanocatalysts under Harsh Temperature Conditions

By depositing ceria on the surface of yttrium-stabilized zirconia (YSZ) nanocrystals and further activation under high-temperature reducing conditions, a 13% mol. CeO₂/YSZ catalyst structured as subnanometer thick, pyrochlore-type, ceria-zirconia islands has been prepared. This nanostructured catalyst depicts not only high oxygen storage capacity (OSC) values but, more importantly, an outstandingly stable redox response upon oxidation and reduction treatments at very high temperatures, above 1000 °C. This behavior largely improves that observed on conventional ceria-zirconia solid solutions, not only of the same composition but also of those with much higher molar cerium contents. Advanced scanning transmission electron microscopy (STEM-XEDS) studies have revealed as key not only to detect the actual state of the lanthanide in this novel nanocatalyst but also to rationalize its unusual resistance to redox deactivation at very high temperatures. In particular, high-resolution X-ray dispersive energy studies have revealed the presence of unique bilayer ceria islands on top of the surface of YSZ nanocrystals, which remain at surface positions upon oxidation and reduction treatments up to 1000 °C. Diffusion of ceria into the bulk of these crystallites upon oxidation at 1100 °C irreversibly deteriorates both the reducibility and OSC of this nanostructured catalyst