Synthesis, Physicochemical Characterization, and Cytotoxicity Assessment of CeO2 Nanoparticles with Different Morphologies

α-Glucosidase Inhibitory Activity and Cytotoxicity of CeO2 Nanoparticles Fabricated Using a Mixture of Different Cerium Precursors

A mixture of three distinct cerium precursors (Ce(NO3)3·6H2O, CeCl3·7H2O, and Ce(CH3COO)3·H2O) was used to prepare cerium oxide nanoparticles (CeO2 NPs) in a polyol-mediated synthesis. Different ratios of diethylene glycol (DEG) and H2O were utilized in the synthesis. The properties of the synthesized CeO2 NPs, such as structural and morphological properties, were investigated to observe the effect of the mixed cerium precursors. Crystallite sizes of 7-8 nm were obtained for all samples, and all synthesized samples were confirmed to be in the cubic phase. The average particle sizes of the spherical CeO2 were between 9 and 13 nm. The successful synthesis of CeO2 can also be confirmed via the vibrational band of Ce-O from the FTIR. Antidiabetic properties of the synthesized CeO2 NPs were investigated using α-glucosidase enzyme inhibition assay, and the concentration of the synthesized CeO2 NPs was varied in the study. The biocompatibility properties of the synthesized CeO2 NPs were investigated via cytotoxicity tests, and it was found that all synthesized materials showed no cytotoxic properties at lower concentrations (62.5-125 μg/mL).

Effects of NO3-, Cl-, and CH3COO- anions and diethylene glycol on the morphological, structural, antidiabetic, and cell viability properties of CeO2 nanoparticles

Cerium oxide (CeO₂) nanoparticles (NPs) were synthesized using a modified conventional polyol method. The ratio of diethylene glycol (DEG) and water in the synthesis was varied, and three different cerium precursor salts (Ce(NO₃)₃, CeCl₃, and Ce(CH₃COO)₃) were used. The structure, size, and morphology of the synthesized CeO₂ NPs were studied. An average crystallite size of 13 to 33 nm was obtained from the XRD analysis. Spherical and elongated morphologies of the synthesized CeO₂ NPs were acquired. Average particle sizes in the range of 16-36 nm were obtained by varying different ratios of DEG and water. The presence of DEG molecules on the surface of CeO₂ NPs was confirmed using FTIR. Synthesized CeO₂ NPs were used to study the antidiabetic and cell viability (cell cytotoxicity) properties. Antidiabetic studies were carried out using α-glucosidase enzymes inhibition activity. CeO₂ synthesized using Ce(NO₃)₃ and CeCl₃ precursors showed approximately 40.0% α-glucosidase enzyme inhibition activity, while CeO₂ synthesized using Ce(CH₃COO)₃ showed the lowest α-glucosidase enzyme inhibition activity. Cell viability properties of CeO₂ NPs were investigated using an in vitro cytotoxicity test. CeO₂ NPs prepared using Ce(NO₃)₃ and CeCl₃ were non-toxic at lower concentrations, while CeO₂ NPs prepared using Ce(CH₃COO)₃ were non-toxic at all concentrations. Therefore, polyol-mediated synthesized CeO₂ NPs showed quite good α-glucosidase inhibition activity and biocompatibility.

Towards the Development of Antioxidant Cerium Oxide Nanoparticles for Biomedical Applications: Controlling the Properties by Tuning Synthesis Conditions

In this work CeO₂ nanoparticles (CeO₂-NPs) were synthesized through the thermal decomposition of Ce(NO₃)₃·6H₂O, using as capping agents either octylamine or oleylamine, to evaluate the effect of alkyl chain length, an issue at 150 °C, in the case of octylamine and at 150 and 250 °C, in the case of oleylamine, to evaluate the effect of the temperature on NPs properties. All the nanoparticles were extensively characterized by a multidisciplinary approach, such as wide-angle X-ray diffraction, transmission electron microscopy, dynamic light scattering, UV-Vis, fluorescence, Raman and FTIR spectroscopies. The analysis of the experimental data shows that the capping agent nature and the synthesis temperature affect nanoparticle properties including size, morphology, aggregation and Ce³⁺/Ce⁴⁺ ratio. Such issues have not been discussed yet, at the best of our knowledge, in the literature. Notably, CeO₂-NPs synthesized in the presence of oleylamine at 250 °C showed no tendency to aggregation and we made them water-soluble through a further coating with sodium oleate. The obtained nanoparticles show a less tendency to clustering forming stable aggregates (ranging between 14 and 22 nm) of few NPs. These were tested for biocompatibility and ROS inhibiting activity, demonstrating a remarkable antioxidant activity, against oxidative stress.

Silica-Coated TiN Particles for Killing Cancer Cells

Photothermal therapy (PTT) using plasmonic nanoparticles for cancer treatment is on the verge of clinical application. Titanium nitride (TiN) nanoparticles offer a promising alternative to commonly used gold-based systems at a fraction of the costs. Little is known, however, about the relationship between TiN particle characteristics and their optical properties in colloidal systems. Here, TiN nanoparticles with closely controlled characteristics are prepared by nitridation of TiO₂, and their use as PTT agents is explored. Emphasis is placed on the particle surface and core oxygen content, which dominate the TiN optical properties. Colloidal suspensions were studied under UV-vis and near-infrared (NIR) laser irradiation and correlated to particle characteristics. High nitridation temperatures and long residence times lead to increased NIR light absorption. Too high nitridation temperatures, however, lead to particle aggregation that deteriorated their optical properties. This was overcome with SiO₂ coating of TiO₂ nanoparticles prior to nitridation: the resulting SiO₂-coated TiN particles exhibited increased plasmonic performance compared to bare TiN, which is attributed to reduced plasmonic coupling effects. The optimized SiO₂-coated TiN had a photothermal efficiency of 58.5% and mass extinction coefficient of 31.6 L g^-1 cm^-1, outperforming commercial gold nanoshells that are used in clinical trials. The potential of SiO₂-coated TiN for photothermal therapy was demonstrated by controllably killing HeLa cells in vitro.