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.12 página

Enhanced Artificial Enzyme Activities on the Reconstructed Sawtoothlike Nanofacets of Pure and Pr-Doped Ceria Nanocubes

In this work, a simple one-step thermal oxidation process was established to achieve a significant surface increase in {110} and {111} nanofacets on well-defined, pure and Pr-doped, ceria nanocubes. More importantly, without changing most of the bulk properties, this treatment leads to a remarkable boost of their enzymatic activities: from the oxidant (oxidase-like) to antioxidant (hydroxyl radical scavenging) as well as the paraoxon degradation (phosphatase-like) activities. Such performance improvement might be due to the thermally generated sawtoothlike {111} nanofacets and defects, which facilitate the oxygen mobility and the formation of oxygen vacancies on the surface. Finally, possible mechanisms of nanoceria as artificial enzymes have been proposed in this manuscript. Considering the potential application of ceria as artificial enzymes, this thermal treatment may enable the future design of highly efficient nanozymes without changing the bulk composition.This work has been supported by the Ministry of Science, Innovation and Universities of Spain with Reference Numbers of ENE2017-82451-C3-2-R, MAT2016-81118-P and MAT2017-87579-R. The research projects funded by the Natural Science Foundation of Shandong Province (Grant ZR2017LB028), Key R&D Program of Shandong Province (Grant 2018GSF118032), and Fundamental Research Funds for the Central Universities (Grant 18CX02125A) in China are also acknowledged. TEM/STEM data were obtained at DMEUCA node of the Spanish Unique Scientific and Technological Infrastructure (ICTS) of Electron Microscopy of Materials ELECMIM. M. Tinoco thanks the FPU Scholarship Program (Grant AP2010-3737) from Ministry of Education of Spain. H. Pan is grateful for financial support (Grant 201406140130) from the Chinese Scholarship Council to accomplish her Ph.D. study at the University of Cadiz (Spain). J. M. Gonzalez, G. Blanco, and X. Chen are also grateful for the financial support from the joint project (Proyectos Integradores, Grant PI20201) in IMEYMAT of the University of Cadiz

Dialogando sobre agricultura familiar: Visión de futuro para Centroamérica. Síntesis de webinar 5

Síntesis de webinar 5Se presentan los temas principales en el interés de la agricultura familia Centroamericana; se abordan los procesos de comunicación para el desarrollo y gestión de conocimiento, promueve la formación de comunidades de práctica en donde los productores líderes se van formando como gestores de conocimiento y a su vez forman a otros en un proceso de propagación autogestionario

Dialogando sobre agricultura familiar: Visión de futuro para Centroamérica. Síntesis de webinar 4

Síntesis de webinar 4Se presentan los temas principales en el interés de la agricultura familia Centroamericana; el Sistema de Innovación Agrícola (SIA) para la adopción de nuevos productos, se observan las estrategias para generar conocimiento y tecnología para las condiciones de las familias productoras de la agricultura familiar, la innovación y desarrollo en adopción de procesos que permitan el acceso a nuevas técnicas

Metallic edge states in zig-zag vertically-oriented MoS2 nanowalls

Depto. de Química InorgánicaFac. de Ciencias QuímicasTRUEpu

A Macroscopically Relevant 3D-Metrology Approach for Nanocatalysis Research

A 3D nanometrological approach, which considers as an unbiased validation criterion the quantitative match between values of properties determined by macroscopic characterization techniques and those determined from the nanoscopic results, is developed to unveil the details of complex nanocatalysts. This approach takes into account both the peculiar characteristics of this type of materials and the large influence of noise in the tilt series. It combines, in an optimized way, the latest experimental developments in high angle annular dark field scanning transmission electron microscopy mode (HAADF-STEM) tomography, such as batch tomography, image denoising by undecimated wavelet transforms, improved reconstructions by total variation minimization and a more efficient, user-independent, segmentation scheme. To illustrate the use of this novel approach, the 3D structural characterization of a model nanocatalyst comprising gold nanoparticles dispersed on the surface of CeO2 nanocubes is performed, and the obtained results used to compute the values of different macroscopic chemical and textural properties. Comparison with values obtained by macroscopic characterization techniques match very closely those obtained by 3D nanometrology. Importantly, the new approach described in this work also illustrates a pipeline for nearly fully automated HAADF-STEM tomography studies, guaranteeing reliable correlations between nanoscopic and macroscopic properties.Depto. de Química InorgánicaFac. de Ciencias QuímicasTRUEpu

Influence of {111} nanofaceting on the dynamics of CO adsorption and oxidation over Au supported on CeO2 nanocubes: An operando DRIFT insight

CO adsorption and further reaction with O2 on two Au/CeO2 model systems have been investigated by operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) in order to unveil the active sites for CO oxidation. One of the ceria supports was constituted by crystallites depicting a nanocube shape bounded mostly by {100} planes, whilst the second one was consisted of nanocubes whose {110} surfaces were reconstructed into {111}-nanofacets with a zig-zag shape. The deconvolution of the CO adsorption bands and a detailed analysis of the time-evolution of these bands were also carried out. These studies evidenced a fast adsorption of CO over Au° and then Auδ--CO bands appeared during exposure to CO, in parallel with the appearance of Ce3+ features. Such changes suggest that CO adsorption process starts on Au sites on the low coordinated sites of the surface of the Au nanoparticles and their transfer to the interface sites. By comparing the nanostructure of the two catalysts, the Auδ--CO species could be fruitfully related to CO adsorption on sites located at the Au||CeO2 perimeter. The sample containing gold nanoparticles dispersed over the {111}-nanofaceted CeO2 nanocubes, which retained a higher amount of gold nanoparticles, depicts higher contribution of Auδ−−CO bands than the other Au catalyst in the DRIFT spectra. The dynamic DRIFT study clearly revealed that the CO species adsorbed on Auδ- sites were the most reactive ones in both gold supported systems for CO oxidation. This explains much higher TOF values observed on the catalyst prepared on the surface reconstructed support. A detailed analysis on the reactivity was performed by modulation excitation spectroscopy (MES). The presence of peroxide surface species (O2 2-) in nanofaceted {111} could lead to higher catalytic activity than that of gold on the non-reconstructed catalyst..Ministerio de Ciencia InnovaciónNational Agency for the Promotion of Science and Technology of ArgentinaDepto. de Química InorgánicaFac. de Ciencias QuímicasTRUEpu

CeO2-modified Au/TiO2catalysts with outstanding stability underharsh CO oxidation conditions

Depto. de Química InorgánicaFac. de Ciencias QuímicasTRUEpu

Enzyme-Free Colorimetric Method for Fast Detection of PIK3CA Gene Mutation by Praseodymia Nanorods

Depto. de Química InorgánicaFac. de Ciencias QuímicasTRUEpu