CeO2 nanostructured electrochemical sensor for the simultaneous recognition of diethylstilbestrol and 17β-estradiol hormones

A new highly sensitive, selective, and inexpensive electrochemical method has been developed for simultaneously detecting diethylstilbestrol (DES) and 17β-estradiol (E2) in environmental samples (groundwater and lake water) using a graphite sensor modified by cerium oxide nanoparticles (CPE-CeO₂ NPs). The developed sensor and the materials used in its preparation were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The ab initio simulation was used to evaluate the adsorption energies between both DES and E2 with the surface of the sensor. The peak current of oxidation of both hormones showed two regions of linearity. The region of greatest sensitivity was observed for the linear range of 10 nM-100 nM. The detection and quantification limits for this concentration range were 0.8/2.6 nM and 1.3/4.3 nM for DES and E2, respectively. The analytical performance of the developed method showed high sensitivity, precision, repeatability, reproducibility, and selectivity. The CPE-CeO₂ NPs sensor was successfully applied to simultaneously detect DES and E2 in real samples with recovery levels above 98%.

Magnetically retrievable Ce-doped Fe3O4 nanoparticles as scaffolds for the removal of azo dyes

Considering the significant impact of magnetically retrievable nanostructures, herein, Fe3O4 and Ce-doped Fe3O4 nanoparticles were employed as scaffolds for the removal of the Reactive Black 5 (RB5) azo dye. We synthesized the Ce-doped Fe3O4 nanoparticles via hydrothermal treatment at 120 °C for 10 h with varying cerium concentrations (1.5-3.5%) and characterized them using basic techniques such as FTIR and UV-visible spectroscopy, and XRD analysis. The retention of their magnetic behaviors even after cerium amalgamation was demonstrated and confirmed by the VSM results. FESEM and EDX were used for the morphological and purity analysis of the synthesized nanoabsorbents. XPS was carried out to determine the electronic configuration of the synthesized samples. The porosity of the magnetic nanoparticles was investigated by BET analysis, and subsequently, the most porous sample was further used in the adsorption studies for the cleanup of RB5 from wastewater. The dye adsorption studies were probed via UV-visible spectroscopy, which indicated the removal efficiency of 87%. The prepared Ce-doped Fe3O4 nanoabsorbent showed the high adsorption capacity of 84.58 mg g-1 towards RB5 in 40 min. This is attributed to the electrostatic interactions between the nanoabsorbent and the dye molecules and high porosity of the prepared sample. The adsorption mechanism was also analyzed. The kinetic data well-fitted the pseudo-first-order model, and the adsorption capability at different equilibrium concentrations of the dye solution indicated monolayer formation and chemisorption phenomena. Furthermore, the magnetic absorbent could be rapidly separated from the wastewater using an external magnetic field after adsorption.

Functionalization of Cerium Oxide Nanoparticles to Influence Hydrophobic Properties

Electroless functionalization of cerium oxide nanoparticles (NPs) based on the grafting of aryl groups from the reduction of diazonium salts is presented as a useful and facile method for enhancing the properties of the NPs. For this study, 4-methyl-, 4-ethyl-, and 4- n-butyl-benzene diazonium salts were used as model molecules to demonstrate the ability to change the hydrophobic properties of the cerium oxide (CeO₂) NPs. The grafting reaction was investigated under two reducing environments: the addition of a chemical reducing agent and the use of cerium oxide's native reducing property. Spectroscopic evidence for the successful attachment of aryl groups to the CeO₂ NPs was given by infrared and ¹³C SS-NMR, which clearly detect characteristic aryl C-C peaks and the alkyl chains. X-ray diffraction results confirmed that the NPs underlying the crystal structure was unaffected by the grafting process. Thermal gravimetric analysis of the NPs suggested that this method enables the formation of multilayers at the surface, as well as an increase in the hydrophobic character. Hydrophobic properties of the resultant NPs further examined with a water contact angle test on pressed pellets revealed increase in hydrophobicity with increasing alkyl chain length. This research opens up new possibilities for controlling the surface chemical composition of CeO₂ NPs as well as other NPs using procedures operated in aqueous environments at room temperature.

Green synthesis of labeled CeO2 nanoparticles with 99mTc and its biodistribution evaluation in mice

AIMS

The in vivo targeted diagnostic applications of biosynthetic Cerium oxide nanoparticles (CeO₂-NPs), prepared by applying chitosan as a stabilizer, was explored by evaluating the cytotoxicity through MTT assay on WEHI 164 cell line, the Hemolytic activity of CeO₂-NPs and biodistribution in rats.

MAIN METHODS

The CeO₂-NPs were characterized through the use of TGA/DTG, PXRD, FESEM, FTIR, and UV-Vis spectroscopy. The biodistribution of CeO₂-NPs were determined by directly labeled nanoparticles with Technetium-99 m (99mTc) radioisotope (99mTc-CeO₂-NPs). The labeling efficiency and stability of 99mTc-CeO₂-NPs were also measured with Instant Thin Layer Chromatography (ITLC) method. The saturation study was investigated by 1 mCi of 99mTc-CeO₂-NPs using different concentrations of WEHI 164 cells after 4 h of incubation. In vivo biodistribution study was performed by intravenous injection of 600 μCi/200 μL 99mTc-CeO₂-NPs through rat's tail.

KEY FINDINGS

CeO₂-NPs seemed to have a low cytotoxic effect on WEHI 164 cell line and did not result in hemolysis. The biodistribution of CeO₂-NPs has shown that a huge amount of 99mTc-CeO₂-NPs was amassed in the living human organs, including liver, lung, spleen, stomach, and thyroid which shows the in vivo stability of the labeled conjugate. Herein, we have developed a facile, economical, and greener synthetic procedure applying Chitosan template. This green approach is comparable to conventional methods that utilize hazardous materials which are would be a suitable alternative to circumvent synthetic issues related to these materials.

SIGNIFICANCE

The bio-applications of nano-sized CeO₂-NPs were explored to find new horizon to use nanotechnology as the diagnostic tool.

Bio-therapeutic Potential and Cytotoxicity Assessment of Pectin-Mediated Synthesized Nanostructured Cerium Oxide

In the present studies, renewable and nontoxic biopolymer, pectin, was extracted from Indian red pomelo fruit peels and used for the synthesis of cerium oxide nanoparticles (CeO₂-NPs) having bio-therapeutic potential. The structural information of extracted pectin was investigated by FTIR and NMR spectroscopic techniques. Physicochemical characteristics of this pectin suggested its application in the synthesis of metal oxide nanoparticles. Using this pectin as a template, CeO₂-NPs were synthesized by simple, one step and eco-friendly approach. The UV-Vis spectrum of synthesized CeO₂-NPs exhibited a characteristic absorption peak at wavelength 345 nm, which can be assigned to its intrinsic band gap (3.59 eV) absorption. Photoluminescence measurements of CeO₂-NPs revealed that the broad emission was composed of seven different bands. FTIR analysis ensured involvement of pectin in the formation and stabilization of CeO₂-NPs. FT-Raman spectra showed a sharp Raman active mode peak at 461.8 cm^-1 due to a symmetrical stretching mode of Ce-O vibration. DLS, FESEM, EDX, and XRD analysis showed that the CeO₂-NPs prepared were polydispersed, spherical shaped with a cubic fluorite structure and average particle size ≤40 nm. These CeO₂-NPs displayed broad spectrum antimicrobial activity, antioxidant potential, and non-cytotoxic nature.

Influence of Bath Composition at Acidic pH on Electrodeposition of Nickel-Layered Silicate Nanocomposites for Corrosion Protection

Nickel-layered silicates were electrochemically deposited from acidic bath solutions. Citrate was used as a ligand to stabilize nickel (II) ions in the plating solution. The silicate, montmorillonite, was exfoliated by stirring in aqueous solution over 24 hours. The plating solutions were analyzed for zeta-potential, particle size, viscosity, and conductivity to investigate the effects of the composition at various pHs. The solution particles at pH 2.5 (−22.2 mV) and pH 3.0 (−21.9 mV) were more stable than at pH 1.6 (−10.1 mV) as shown by zeta-potential analysis of the nickel-citrate-montmorillonite plating solution.Ecorrfor the films ranged from −0.32 to −0.39 V with varying pH from 1.6 to 3.0. The films were immersed in 3.5% NaCl and the open circuit potential monitored for one month. The coatings deposited at pH 3.0 were stable 13 days longer in the salt solution than the other coatings. X-ray diffraction showed a change in the (111)/(200) ratio for the coatings at the various pHs. The scanning electron microscopy and hardness results also support that the electrodeposition of nickel-montmorillonite at pH 3.0 (234 GPa) had improved hardness and morphology compared to pH 2.5 (174 GPa) and pH 1.6 (147 GPa).

Facile electrochemical synthesis of single crystalline CeO2 octahedrons and their optical properties

We developed a simple electrochemical process for the large-scale fabrication of single crystalline CeO(2) octahedrons and nanospheres from DMSO aqueous solution. The octahedrons with some structural defects have a size ranging from 200 to 300 nm. Moreover, highly crystalline CeO(2) nanospheres were also obtained via this electrochemical process based on the oriented attachment mechanism. The absorption edge of octahedrons and spheres shows a red-shift, and that of the octahedrons was near the visible region.