Synthesis and biomedical applications of Cerium oxide nanoparticles - A Review.

Cerium oxide nanoparticles (nanoceria; CNPs) have been found to have both pro-oxidant and anti-oxidant effects on different cell systems or organisms. In order to untangle the mechanisms which underlie the biological activity of nanoceria, we have studied the effect of five different CNPs on a model relevant aquatic microorganism. Neither shape, concentration, synthesis method, surface charge (ζ-potential), nor nominal size had any influence in the observed biological activity. The main driver of toxicity was found to be the percentage of surface content of Ce3+ sites: CNP1 (58%) and CNP5 (40%) were found to be toxic whereas CNP2 (28%), CNP3 (36%) and CNP4 (26%) were found to be non-toxic. The colloidal stability and redox chemistry of the most and least toxic CNPs, CNP1 and CNP2, respectively, were modified by incubation with iron and phosphate buffers. Blocking surface Ce3+ sites of the most toxic CNP, CNP1, with phosphate treatment reverted toxicity and stimulated growth. Colloidal destabilization with Fe treatment only increased toxicity of CNP1. The results of this study are relevant in the understanding of the main drivers of biological activity of nanoceria and to define global descriptors of engineered nanoparticles (ENPs) bioactivity which may be useful in safer-by-design strategies of nanomaterials.

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Untangling the biological effects of cerium oxide nanoparticles: the role of surface valence states.

Synthesis and Characterization of Cerium Oxide Nanoparticles by Hydroxide Mediated Approach

Role of cetyltrimethylammonium bromide (CTAB) surfactant micelles on kinetics of [Zn(II)-Gly-Leu]+ and ninhydrin

Effect of Zn doping on structural, optical and thermal properties of CeO2 nanoparticles

In the present work, the cerium nitrate hexa-hydrate and ammonium hydroxide, used as the starting materials and the weakly agglomerated cerium oxide nanoparticles was synthesized by simple and cost effective reverse co-precipitation method. The effect of aging time and calcination temperature on structural properties of synthesized nanopowder was investigated by X-ray diffractometry (XRD), simultaneous thermal analysis (STA), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM) analytical methods. The investigation showed that aging of the precipitated precursors has pronounced effect on the decreasing of the agglomeration, increase in the crystallinity and the crystallite size of the final product obtained after calcination. Also, increase in the calcination temperature led to the appreciable increase in the crystallite size as well as the crystallinity.

	 

	Key words: Aging time, ammonium hydroxide, calcination temperature, ceria nanoparticles, reverse co-precipitation.

/pdf/effect-of-aging-time-and-calcination-temperature-on-the-1vi73qwbsb.pdf

Effect of aging time and calcination temperature on the cerium oxide nanoparticles synthesis via reverse co- precipitation method

This paper reports the synthesis and characterization of CeO2 nanoparticles via a simple and cost-effective co-precipitation method using cerium (III) nitrate hexahydrate, ammonium carbonate, cetyltrimethylammonium bromide (CTAB) and polyvinyl pyrrolidone (PVP) as the starting chemicals. The precursor was calcined at 600 °C for 2 h to obtain CeO2 nanoparticles. The X-ray diffraction and Fourier transform infrared spectroscopy analysis results indicated that the calcined CeO2 sample has the fluorite structure of CeO2 and adding surfactant increases the obtained CeO2 amount. Transmission electron microscopy revealed that the CeO2 samples consist of crystalline particles of 5–8 nm which are weakly aggregated and using the surfactants further decreases the agglomeration. The effects of PVP in decreasing the crystallite size and agglomeration, as well as, increasing the obtained CeO2 amount have been greater than for CTAB.

Effects of PVP and CTAB surfactants on the morphology of cerium oxide nanoparticles synthesized via co-precipitation method

In this paper, the size dependent behavior of the gold micro-switches has been studied. This behavior becomes noticeable for a structure when the characteristic size such as thickness or diameter is close to its internal length-scale parameter. The size dependent effect is insignificant for the high ratio of the characteristic size to the length-scale parameter, which is the case of the silicon base micro-beams. On the other hand, in some types of micro-beams like gold base, the size dependent effect cannot be overlooked. In such cases, ignoring this behavior in modeling will lead to incorrect results. Some previous researchers have applied classic beam theory on their models and imposed a considerable hypothetical value of residual stress to match their theoretical results with the experimental ones. In this study, by obtaining the equilibrium positions or fixed points of the gold micro-beam, a considerable difference between the obtained fixed points using classic beam theory and modified couple stress theory has been shown. In addition, it has been shown that the calculated pull-in voltages using modified couple stress theory are much closer to the experimental results than those obtained by classic beam theory. Finally, it has been shown that considering a unique value of length scale parameter, especially for the smallest values of the beam thicknesses, may leads to inaccurate results and variable length scale parameter should be considered. © 2011 IAU, Arak Branch. All rights reserved.

http://jsm.iau-arak.ac.ir/article_514403_a7a140f0084cf14697865209ac9db05c.pdf

Study on the Pull-In Instability of Gold Micro-Switches Using Variable Length Scale Parameter

This paper presents a study on the frequency response of a capacitive micro-beam resonator under various applied stresses. The governing equation whose solution holds the answer to all our questions about the mechanical behavior is the nonlinear electrostatic equation. Due to the nonlinearity and complexity of the derived equation analytical solution are not generally available; therefore, the obtained differential equation has been solved by using a step by step linearization scheme and a Galerkin based reduced order model. The obtained static pull-in voltages have been validated by previous reports and a good agreement has been achieved. The dynamic behavior of the beam under residual, axial and thermal stresses has been investigated. It has been shown that applying the positive residual stress and negative temperature changes shifts right the frequency response and decrease the vibration amplitude and vice versa. Also, it has been shown that applying the bias DC voltage beside the exciting AC voltage decreases the stiffness of the system and so, shifts left the frequency response and increases the vibration amplitude.

http://jsm.iau-arak.ac.ir/article_514495_b334dad44e98795d7bb1e5cfc68a17c5.pdf

Marzieh Jalilpour

Papers

Effect of aging time and calcination temperature on the cerium oxide nanoparticles synthesis via reverse co- precipitation method

Effects of PVP and CTAB surfactants on the morphology of cerium oxide nanoparticles synthesized via co-precipitation method

Study on the Pull-In Instability of Gold Micro-Switches Using Variable Length Scale Parameter

Frequency response analysis of a capacitive micro-beam resonator considering residual and axial stresses and temperature changes effects

Soil Chemico-biological Properties Affected by the Interactions of Long-term Non-cultivation Practices and Grazing