Toxicological assessment of tungsten oxide nanoparticles in rats after acute oral exposure.

Advances in and the rapid growth of the nanotechnology sector have escalated manufacture of nanoparticles (NPs), resulting in a significant increase in the probability of exposure of humans and wildlife to these materials. Many NPs have been found to exert genotoxicity. Therefore, genotoxicity studies are mandatory to assess the toxicity of NPs as a concern of succumbing to genetic diseases and cancers are universal. Tungsten oxide (WO3) NPs are being explored extensively in various fields. However, the toxicological data of WO3 NPs by oral route in mammals is limited. Hence, the goal of the current investigation was to evaluate the acute toxicity of WO3 NPs and microparticles (MPs) after single oral administration with 100, 500 and 1000 mg/kg body weight doses in female Wistar rats. TEM, dynamic light scattering and laser Doppler velocimetry techniques were used to characterise the particles. The genotoxicity studies were conducted using comet, micronucleus and chromosomal aberration assays. Alterations in biochemical indices and metal distribution in various organs were also evaluated. The mean size of WO3 NPs and MPs by TEM was 53.2 ± 1.91 nm and 5.17 ± 3.18 µm, respectively. The results revealed a significant increase in DNA damage and micronuclei and chromosomal aberrations after exposure to 1000 mg/kg dose of WO3 NPs. Significant alterations in aspartate transaminase, alanine transaminase, reduced glutathione, catalase and malondialdehyde levels in serum and liver were found only at the higher dose of WO3 NPs. Tungsten (W) biodistribution was observed in all the tissues in a dose-, time- and organ-dependent manner. In addition, the maximum concentration of W was found in the liver and the least in the brain was observed. The test substances were found to have a relatively low acute toxicity hazard. The data obtained gives preliminary information on the potential toxicity of WO3 NPs and MPs.

Genotoxic effects of chromium oxide nanoparticles and microparticles in Wistar rats after 28 days of repeated oral exposure.

The nanotechnology industry has advanced rapidly in the last 10 years giving rise to the growth of the nanoparticles (NPs) with great potential in various arenas. However, the same properties that make NPs interesting raise concerns because their toxicity has not been explored. The in vivo toxicology of chromium oxide (Cr2O3)-NPs is not known till date. Therefore, this study investigated the 28-day repeated toxicity after 30, 300 and 1000 mg/kg body weight (bw)/day oral treatment with Cr2O3-NPs and Cr2O3 microparticles (MPs) in Wistar rats. The mean size of Cr2O3-NPs and Cr2O3-MPs was 34.89 ± 2.65 nm and 3.76 ± 3.41 µm, respectively. Genotoxicity was assessed using comet, micronucleus and chromosomal aberration (CA) assays. The results revealed a significant increase in DNA damage in peripheral blood leucocytes and liver, micronuclei and CA in bone marrow after exposure of 300 and 1000 mg/kg doses of Cr2O3-NPs and Cr2O3-MPs only at 1000 mg/kg bw/day. Cr biodistribution was observed in all the tissues in a dose-dependent manner. The maximum amount of Cr was found in the kidneys and least in the brain of the treated rats. More of the Cr was excreted in the faeces than in the urine. Furthermore, nanotreated rats displayed much higher absorption and tissue accumulation. These findings provide initial data of the probable genotoxicity and biodistribution of NPs and MPs of Cr2O3 generated through repeated oral treatment.

Genotoxicity assessment of cerium oxide nanoparticles in female Wistar rats after acute oral exposure.

Cerium oxide nanoparticles (CeO2 NPs; nanoceria) have demonstrated excellent potential for commercial use in various arenas, such as in biomedical industry in cosmetics and as a fuel additive. However, limited knowledge exists regarding their potential toxicity. In this study, acute oral toxicity of CeO2 NPs and their microparticles (MPs; bulk) was carried out in female albino Wistar rats. The CeO2 NPs and CeO2 MPs were characterized utilizing transmission electron microscopy (TEM), dynamic light scattering (DLS) and laser Doppler velocimetry (LDV) for the size, distribution and surface charge respectively. The genotoxicity studies were conducted using micronucleus test (MNT), comet and chromosomal aberration (CA) assays. Results revealed that at high dose (1000mg/kg bw) CeO2 NPs induced significant DNA damage in peripheral blood leukocytes (PBL) and liver cells, micronucleus formation in bone marrow and blood cells and total cytogenetic changes in bone marrow. However, significant genotoxicity was not observed at 500 and 100mg/kg bw of CeO2 NPs. The findings from biochemical assays depicted significant alterations in ALP and LDH activity in serum and GSH content in liver, kidneys and brain only at the high dose of CeO2 NPs. Tissue biodistribution of both particles was analyzed by inductively coupled plasma optical emission spectrometer (ICP-OES). Bioaccumulation of nanoceria in all tissues was significant and dose-, time- and organ-dependent. Moreover, CeO2 NPs exhibited higher tissue distribution along with greater clearance in large fractions through urine and feces than CeO2 bulk, whereas, maximum amount of micro-sized CeO2 got excreted in feces. The histopathological examination documented alterations in the liver due to exposure with CeO2 NPs only. Hence, the results suggest that bioaccumulation of CeO2 NPs may induce genotoxic effects. However, further research on long term fate and adverse effects of CeO2 NPs is warranted.

Facile chemical synthesis of W-Ag and W-Cu nanocomposites at low temperature.

W-Ag (80.2W-19.8Ag, 70.4W-29.6Ag and 60.5W-39.5Ag) and W-Cu (79.7W-20.3Cu, 70.5W-29.5Cu and 59.8W-40.2Cu) nanocomposites in the size range of 24-30 nm have been synthesized by thermal decomposition of W(CO)6/CH3COOAg and W(CO)6/Cu(acac)2 in diphenyl ether as solvent at 220 degrees C in presence of oleic acid and hexadecyl amine and characterized. FTIR spectra have been used to explain the role of oleic acid and hexadecyl amine in the synthesis of W-Ag and W-Cu composite powders. XRD studies show that the tungsten phase is amorphous, whereas both Ag and Cu crystallize in fcc for as-synthesized W-Ag and W-Cu nanocomposites. These composite powders when annealed at 700 degrees C results in the formation of bcc tungsten and peaks corresponding to fcc silver and copper still persists. The particle size, shape and distribution of these nanocomposites of various compositions have been studied by SAXS, ESEM and TEM and found to be nearly spherical with the average diameters below 30 nm.

A novel green chemical route for synthesis of silver nanoparticles using camellia sinensis.

The thrust to develop environmental friendly procedures for production of Nanoparticles arises from the very fact that current nanotechnology research uses a lot of chemicals, which are potential threat to both environment and public health. Tea (Camellia Sinensis) with its rich source of polyphenolic compounds has been exploited for the reduction and capping of silver nanoparticles (Ag-NPs), making it a complete green chemical route. The reduction of Ag+ to Ag0 was observed by the color change from pale yellow to dark yellow. The reaction was followed with the help of UV-Visible spectrometer. Crystal structure was obtained by carrying out X-ray diffraction studies and it showed face centered cubic (fcc) structure. The particle size and morphology were obtained from transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) studies. An average particle size of 25 nm silver particles could be obtained using this method and the TEM and SAXS data corroborate with each other.