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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.

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This study aims at determining the concentration of heavy metal contaminants in the soil around Dangote cement factory Kogi State, Nigeria. It also seeks to understand the relationship between the heavy metals and the level of concentration with respect to distance and direction as well as the ecological risk it poses. The monitoring and assessment of soil pollution have over the years become a very important area of study due to the significant threat it poses to the food web. A total of 33 soil samples were collected in the Northern, Eastern and Western axis within a radius of 4km of Dangote cement factory at a depth of 0-15cm using a stainless steel auger. The contamination factor indices for Cr and Cu show moderate pollution across all the samples collected from different axis at a different distance from the factory. Zn also pose a moderate pollution across the samples except for WK4 and NK4 where it is in a low level of contamination. The geo-accumulation indices for Pb and Cr show unpolluted to moderately polluted across all samples at different locations expect for sample location EK4. The results of the ecological risk assessment revealed that Cd poses the highest ecological risk of all the five heavy metals investigated.