Recent Progress of Rare Earth Oxides for Sensor, Detector, and Electronic Device Applications: A Review

The responses of cells exposed to nanoparticles have been studied with regard to toxicity, but very little attention has been paid to the possibility that some types of particles can protect cells from various forms of lethal stress. It is shown here that nanoparticles composed of cerium oxide or yttrium oxide protect nerve cells from oxidative stress and that the neuroprotection is independent of particle size. The ceria and yttria nanoparticles act as direct antioxidants to limit the amount of reactive oxygen species required to kill the cells. It follows that this group of nanoparticles could be used to modulate oxidative stress in biological systems.

A facile hydrothermal process was used to prepare nanostructures of ZnO/Yb 2 O 3 in alkaline medium, which were applied for efficient chemical sensor development. The sensor fabricated with ZnO/Yb 2 O 3 nanostructures may be a promising sensitive chemical sensor for the effective detection of environmental effluents. In this study, a facile hydrothermal process was used to prepare the NSs of ZnO/Yb 2 O 3 in an alkaline medium (pH ∼ 10.5), at a low temperature. The calcined NSs were characterized by Fourier-transform infrared spectroscopy (FTIR), ultraviolet visible spectroscopy (UV/vis), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). A thin layer of NSs was coated on a glassy carbon electrode (GCE) with the help of a nafion conducting binder to be used as a sensor. This assembled sensor was implemented to the successful detection of 4-AP and exhibited good sensitivity (5.063 μA μM −1 cm −2 ) and a low detection limit (DL = 0.019 ± 0.001 nM at a signal to noise ratio of 3). The calibration plot (attained at a potential of +1.0 V) is linear ( r 2 = 0.9836) in the concentration range of 0.1 nM to 0.1 mM of 4-AP. Therefore, the chemical sensor fabricated with ZnO/Yb 2 O 3 NSs may be a promising sensitive chemical sensor in a reliable I – V method for the effective detection of hazardous and carcinogenic chemicals in environmental and healthcare sectors on broad scales.

We report on the design and development of a glutamate oxidase (GmOx) microelectrode for measuring l-glutamic acid (GluA) in oxygen-depleted conditions, which is based on the oxygen storage and release capacity of cerium oxides. To fabricate the biosensor, a nanocomposite of oxygen-rich ceria and titania nanoparticles dispersed within a semi-permeable chitosan membrane was co-immobilized with the enzyme GmOx on the surface of a Pt microelectrode. The oxygen delivery capacity of the ceria nanoparticles embedded in a biocompatible chitosan matrix facilitated enzyme stabilization and operation in oxygen free conditions. GluA was measured by amperometry at a working potential of 0.6 V vs Ag/AgCl. Detection limits of 0.594 µM and 0.493 µM and a sensitivity of 793 pA/µM (RSD 3.49%, n=5) and 395 pA/µM (RSD 2.48%, n=5) were recorded in oxygenated and deoxygenated conditions, with response times of 2s and 5s, respectively. The biosensor had good operational stability and selectivity against common interfering substances. Operation of the biosensor was tested in cerebrospinal fluid. Preliminary in vivo recording in Sprague-Dawley rats to monitor GluA in the cortex during cerebral ischemia and reperfusion demonstrate a potential application of the biosensor in hypoxic conditions. This method provides a solution to ensure functionality of oxidoreductase enzymes in oxygen-free environments. © 2013 Elsevier B.V. All rights reserved.