Synthesis of Ceria (CeO₂) Nanoparticles and Their Application in Colorimetric Probes for the Determination of Ascorbic Acid

Abstract

Nanoceria (CeO 2 nanoparticles) are among the most unique and promising lanthanide nanomaterials with sensing applicability. In this study, the redox reactivity of nanoceria was exploited for biomedical application based on changes in the physicochemical properties of the nanoparticles on interaction with ascorbic acid (Vitamin C). Nanoceria were synthesized by the microwave-assisted method using ammonium ceric nitrate [(NH 4 ) 2 Ce(NO 3 ) 6 ] as the precursor and diethylene glycol (DEG) as the stabilizer and capping agent. The powder X-ray diffraction (p-XRD) studies of the nanoparticles showed that the synthesized particles are of a pure single-phase matched with a cubic structure. Data from Scanning Electron Microscopy (SEM) & Transmission Electron Microscopy (TEM) analysis were also used to estimate the average size of the particles, and a range of value between 6.8-7.1 nm was obtained which agrees with the value obtained using Debye-Sherrer's relation (6.8 � 0.2 nm). On interacting the nanoceria with ascorbic acid, a color change from light yellow to reddish orange (oxidation of ascorbic acid) was observed, and at the same time, the Ce 4 + is being reduced to Ce 3 + . The reaction between the nanoceria and ascorbic acid was done at a constant concentration of nanoceria with varying amounts of ascorbic acid. This reaction was monitored using the UV-Vis Spectrometry, and the spectra obtained showed that the intensity of the peak decreases with decreasing concentration of the ascorbic acid. Furthermore, the reduction of Ce 4 + to Ce 3 + was justified by the blue shift in the λ max from 344 nm to 254 nm. Data obtained also showed a detection limit of 20 ppm ascorbic acid. The nanoceria were also used to fabricate a paper strip which tested positive for the colorimetric detection of ascorbic acid.

Doped Ceria Nanomaterials: Preparation, Properties, and Uses

“…This surface effect leads to the emergence of interesting properties including a high capacity for oxygen release and storage, good catalytic activity, high refractive index, high transparency in the visible region, and strong UV absorption 3,4 These characteristics have been exploited in various applications including catalysis of three-way reactions to mitigate toxic exhaust gases from automobiles, water−gas shift reactions at low temperature, oxygen sensors, oxygen-permeable membranes, fuel cells, supercapacitors, 5 cancer therapy, photocatalytic pollutant degradation, and polishing agents, 6,7 These diverse applications have prompted the synthesis of ceria by numerous routes including hydrothermal synthesis, coprecipitation, microwave-assisted synthesis, and green synthesis. 8,9 Over the last decade, interest in the preparation of doped ceria nanomaterials has increased. When ceria is doped, extrinsic defects are introduced into its crystal structure, oxygen vacancies are produced, and oxygen migration is improved, all of which lead to enhanced properties.…”

“…In nanomaterials, surface defects become more pronounced compared with the bulk, because the fraction of surface atoms increases with the decreasing size of the particle. This surface effect leads to the emergence of interesting properties including a high capacity for oxygen release and storage, good catalytic activity, high refractive index, high transparency in the visible region, and strong UV absorption , These characteristics have been exploited in various applications including catalysis of three-way reactions to mitigate toxic exhaust gases from automobiles, water–gas shift reactions at low temperature, oxygen sensors, oxygen-permeable membranes, fuel cells, supercapacitors, cancer therapy, photocatalytic pollutant degradation, and polishing agents, , These diverse applications have prompted the synthesis of ceria by numerous routes including hydrothermal synthesis, co-precipitation, microwave-assisted synthesis, and green synthesis. , …”