Synthesis and defect characterization of hybrid ceria nanostructures as a possible novel therapeutic material towards COVID-19 mitigation

Abstract

This study reports the synthesis of hybrid nanostructures composed of cerium dioxide and microcrystalline cellulose prepared by the microwave-assisted hydrothermal route under distinct temperature and pH values. Their structural, morphological and spectroscopic behaviors were investigated by X-Rays Diffraction, Field Emission Gun Scanning Electron Microscopy, High-Resolution Transmission Electron Microscopy, and Fourier-Transform Infrared, Ultraviolet–Visible, Raman and Positron Annihilation Lifetime spectroscopies to evaluate the presence of structural defects and their correlation with the underlying mechanism regarding the biocide activity of the studied material. The samples showed mean crystallite sizes around 10 nm, characterizing the formation of quantum dots unevenly distributed along the cellulose surface with a certain agglomeration degree. The samples presented the characteristic Ce–O vibration close to 450 cm−1 and a second-order mode around 1050 cm−1, which is indicative of distribution of localized energetic levels originated from defective species, essential in the scavenging of reactive oxygen species. Positron spectroscopic studies showed first and second lifetime components ranging between 202–223 ps and 360–373 ps, respectively, revealing the presence of two distinct defective oxygen species, in addition to an increment in the concentration of Ce3+-oxygen vacancy associates as a function of temperature. Therefore, we have successfully synthesized hybrid nanoceria structures with potential multifunctional therapeutic properties to be further evaluated against the COVID-19.

Nanocomposite Catalyst (1 – x)NiO-xCuO/yGDC for Biogas Fueled Solid Oxide Fuel Cells

“…Both figures show an almost identical appearance of the band peaks. A strong typical band around 497 cm –1 is for CeO 2 , which is due to the triply degenerate F 2g active mode of cubic fluorite structure and is related to the symmetrical stretching of Ce–O 8 . , Two main peaks are observed at 908 and 1050 cm –1 , which are related to the transverse and longitudinal modes (TO + LO) of NiO and the second-order mode of CeO 2 , respectively. , Peak intensity decreases with increasing concentration of CuO because the absorption increases with increasing CuO concentration. The broad-band extension is related to the presence of oxygen vacancies.…”

“…34,35 Two main peaks are observed at 908 and 1050 cm −1 , which are related to the transverse and longitudinal modes (TO + LO) of NiO and the second-order mode of CeO 2 , respectively. 36,37 Peak intensity decreases with increasing concentration of CuO because the absorption increases with increasing CuO concentration. The broad-band extension is related to the presence of oxygen vacancies.…”

Positron Annihilation Lifetime Spectroscopy as a Special Technique for the Solid-State Characterization of Pharmaceutical Excipients, Drug Delivery Systems, and Medical Devices—A Systematic Review

“…The results reveal the low intensity of o-Ps formation because almost all of the positrons were annihilated in the CeO 2 quantum dots; this mechanism is essential in scavenging reactive oxygen species (ROS). Furthermore, the effects of the pH and temperature parameters on the manufacturing process were tracked [ 92 ]. ZnO/chitosan biocidal nanocomposites were prepared against Pseudomonas putida , and hole generation related to positron irradiation by PALS was investigated.…”

Facile aqueous synthesis and comparative evaluation of TiO2-semiconductor and TiO2-metal nanohybrid photocatalysts in antibiotics degradation under visible light

“…The synthesis of CeO 2 NPs based on the oxidation of a cerium salt (mainly nitrate or chloride) in basic conditions is common in the literature and it is known that yield monodisperse small-sized (4-5 nm) CeO 2 NPs at this Ce 3+ : NH 4 OH ratio of 1 : 3. 46,54,55 The resulting solution was washed by purication and colloidally stable CeO 2 /TiO 2 were redispersed in a solution of 1 mM TMAOH. Fig.…”