Experimental and modeling study of ZnO:Ni nanoparticles for near-infrared light emitting diodes.

This work is devoted to the synthesis and study of the different properties of ZnO nanoparticles (NPs) doped with the Ni element. We have used a simple co-precipitation technique for the synthesis of our samples and various structural, morphological and optical techniques for their analysis. Energy-Dispersive X-ray spectroscopy (EDX) confirms the stoichiometry of the samples. The X-Ray Diffraction (XRD) patterns reveal the hexagonal wurtzite phase of polycrystalline ZnO with a P63mc space group. Debye Scherrer and Williamson-Hall methods show that the average size of crystallites is around 40 nm. Transmission electron microscopy (TEM) images confirm the XRD results. The optical spectrum of Zn0.95Ni0.5O shows the presence of near-band-edge (NBE) ultraviolet emission. The absorption defect bands appearing near the blue-green region and near infrared emission are attributed to the Ni2+ intra-3d luminescence. The electronic structure of the Ni2+ doped ZnO NPs confirms the T d site symmetry of Ni2+ in the ZnO host crystal and leads to a perfect correlation between calculated and experimental energy levels.

In deep evaluation of the neurotoxicity of orally administered TiO2 nanoparticles.

Titanium dioxide nanoparticles were widely used in food as dietary supplements, in drugs, in toothpaste, ect. Few numbers of studies were interested to the neurotoxicity of TiO2 NPs through oral pathway. The present study aims firstly to understand the connection between the physicochemical properties of TiO2 NPs and their associated toxicological oral pathway by evaluation the colloidal stability of TiO2 NPs over time in different media simulating physiological gastric, intestinal and serum conditions at 37 °C to be close to the oral administraton. Secondly, this study aims to evaluate the neurotoxicity of a subchronic intragastric administration of TiO2 NPs to rats. Different doses of anatase TiO2 NPs were administrated to Wistar rats every day for consecutives eight weeks. Titanium (Ti) content in brain, oxidative antioxidant biomarkers, lipid peroxidation, nitric oxide (NO) levels, tumor necrosis factor-alpha (TNF-α) levels, histophatological changes, degenerated and apoptosis neurons were investigated. Results suggested that TiO2 NPs can reach the brain and cross the brain blood barrier (BBB) to been accumulated in the brain of rats causing cerebral oxidative stress damage, increasing NO levels and histopathological injury. At higher dose, we observed the most cerebral injury by the highest accumulation of Ti and by the remarkable increase of TNF-α besides to the most increase of degenerated and apoptosis neurons in the brain of exposed rats. TiO2 NPs led to a neurotoxic damage accompanied by the increase of degenerated and apoptotic neurons in cerebral cortex.

The effect of titanium dioxide nanoparticles on neuroinflammation response in rat brain.

Titanium dioxide nanoparticles (TiO2 NPs) are widely used for their whiteness and opacity in several applications such as food colorants, drug additives, biomedical ceramic, and implanted biomaterials. Research on the neurobiological response to orally administered TiO2 NPs is still limited. In our study, we investigate the effects of anatase TiO2 NPs on the brain of Wistar rats after oral intake. After daily intragastric administration of anatase TiO2 NPs (5-10 nm) at 0, 50, 100, and 200 mg/kg body weight (BW) for 60 days, the coefficient of the brain, acethylcholinesterase (AChE) activities, the level of interleukin 6 (IL-6), and the expression of glial fibrillary acidic protein (GFAP) were assessed to quantify the brain damage. The results showed that high-dose anatase TiO2 NPs could induce a downregulated level of AChE activities and showed an increase in plasmatic IL-6 level as compared to the control group accompanied by a dose-dependent decrease inter-doses, associated to an increase in the cerebral IL-6 level as a response to a local inflammation in brain. Furthermore, we observed elevated levels of immunoreactivity to GFAP in rat cerebral cortex. We concluded that oral intake of anatase TiO2 NPs can induce neuroinflammation and could be neurotoxic and hazardous to health.

Anemia and genotoxicity induced by sub-chronic intragastric treatment of rats with titanium dioxide nanoparticles.

Titanium dioxide nanoparticles (TiO2 NPs) are widely used for their whiteness and opacity. We investigated the hematological effects and genotoxicity of anatase TiO2 NPs following sub-chronic oral gavage treatment. TiO2-NPs were characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Wistar rats were treated with anatase TiO2 NPs by intragastric administration for 60 days. Hematological analysis showed a significant decrease in RBC and HCT and a significant increase in MCV, PLT, MPV and WBC at higher doses. Furthermore, abnormally shaped red cells, sometimes containing micronuclei, and hyper-segmented neutrophil nuclei were observed with TiO2 NPs treatment. The micronucleus test revealed damage to chromosomes in rat bone marrow at 100 and 200mg/kg bw; the comet assay showed significant DNA damage at the same doses.