Cobalt-mediated generation of reactive oxygen species and its possible mechanism

Leonard, Stephen S.; Gannett, Peter M.; Rojanasakul, Yon; Schwegler‐Berry, Diane; Castranova, Vince; Vallyathan, Val; Shi, Xianglin

doi:10.1016/s0162-0134(98)10022-3

Cited by 167 publications

(107 citation statements)

References 27 publications

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“…No ESR signals are observed either when the photocatalyst is absent or when the reaction is performed with photocatalysts in the dark. After a 2 min of illumination in the presence of photocatalysts a signal centered at g = 2.0065 is observed [22]. The characteristic quartet peaks in the presence of photocatalysts TiO 2 , Pt/TiO 2 , RuO 2 /TiO 2 and Pt-RuO 2 /TiO 2 are assigned to DMPO-OH adduct.…”

Section: The Photocatalytic Degradation Of Rhodamine B (Rhb) and Methmentioning

confidence: 96%

“…No ESR signals were observed either when the photocatalyst was absent or when the reaction was performed with photocatalysts in the dark. After a 10 min of illumination the spectra of the reaction solution in the presence of photocatalysts give a signal centered at g = 2.0065, which indicates oxygen involvement [22]. The signals can be assigned to two groups.…”

Section: The Photocatalytic Degradation Of Rhodamine B (Rhb) and Methmentioning

confidence: 98%

“…The characteristic quartet peaks in the presence of photocatalysts TiO 2 , Pt/TiO 2 , RuO 2 /TiO 2 and Pt-RuO 2 /TiO 2 are assigned to DMPO-OH adduct. The hyperfine splittings are a N = a H = 1.48 mT, where a N and a H denote hyperfine splittings of the nitroxyl nitrogen and a-hydrogen, respectively [22]. And the typical 1:2:2:1 lineshape of DMPO-OH adduct is obtained.…”

Section: The Photocatalytic Degradation Of Rhodamine B (Rhb) and Methmentioning

confidence: 99%

See 2 more Smart Citations

Highly efficient photocatalytic oxidation of sulfur-containing organic compounds and dyes on TiO2 with dual cocatalysts Pt and RuO2

Lin

Zhang

Wang

et al. 2012

Applied Catalysis B: Environmental

100

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Section: The Photocatalytic Degradation Of Rhodamine B (Rhb) and Methmentioning

confidence: 96%

Section: The Photocatalytic Degradation Of Rhodamine B (Rhb) and Methmentioning

confidence: 98%

Section: The Photocatalytic Degradation Of Rhodamine B (Rhb) and Methmentioning

confidence: 99%

See 1 more Smart Citation

Highly efficient photocatalytic oxidation of sulfur-containing organic compounds and dyes on TiO2 with dual cocatalysts Pt and RuO2

Lin

Zhang

Wang

et al. 2012

Applied Catalysis B: Environmental

100

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“…Chromium and cobalt have also been shown to generate free radicals in Fenton-like reactions. 32,33 However, it is not clear what role, if any, molybdenum and nickel might have in a Fenton-like reaction. Our results indicate that nickel can reduce hydrogen peroxide to produce hydroxyl radicals, as observed with CNT-4 (predominantly nickel, with a little cobalt, yttrium and no iron or chromium).…”

Section: Sources Of Toxicity In Carbon Nanotubesmentioning

confidence: 99%

The contributions of metal impurities and tube structure to the toxicity of carbon nanotube materials

et al. 2012

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Due to the existence of considerable quantities of metallic and carbonaceous impurities, the key factor and mechanism for the reported toxicity of carbon nanotubes (CNTs) are unclear. Here, we first quantify the contribution of metal residues and fiber structure to the toxicity of CNTs. Significant quantities of metal particles could be mobilized from CNTs into surrounding fluids, depending on the properties and constituents of the biological microenvironment, as well as the properties of metal particles. Furthermore, electron spin resonance measurements confirm that hydroxyl radicals can be generated by both CNTs containing metal impurities and acid-leachable metals from CNTs. Several biomolecules facilitate the generation of free radicals, which might be due to the participation of these biomolecules in redox cycling influenced by pH. Among several major metal residues, Fe has a critical role in generating hydroxyl radicals, reducing cell viability and promoting intracellular reactive oxidative species. Cell viability is highly dependent on the amount of metal residues and iron in particular, but not tube structure, while the negative effect of CNTs themselves on cell viability is very limited in a certain concentration range below 80 lg ml À1 . It is crucial to systematically understand how these exogenous and endogenous factors influence the toxicity of CNTs to avoid their undesirable toxicity. Keywords: biological microenvironments; carbon nanotube; metal impurities; reactive oxygen species; toxicity INTRODUCTION Engineered nanomaterials possess novel properties and have been used worldwide in numerous consumer products, for example, food, clothes, pharmaceuticals and cleaning products. Estimates suggest that by 2015 nanotechnology will have a trillion-plus dollar global economic impact. 1 Therefore, ensuring the safety of nanomaterials is of great importance to the tremendous commercial applications of nanotechnology. Safety evaluation of nanomaterials should consider their behaviors in various aspects, including their interaction with proteins, DNA, lipids, membranes, organelles, cells, tissues, biological fluids and even the dissolution of metal constituents. [2][3][4] Carbon nanotubes (CNTs) have attracted great interest from both scientists and the industry because their high aspect ratios, strength and remarkable physical properties make them a unique material with a wide range of promising applications. Many applications of CNTs in biomedicine have been proposed, including nanoelectronics, 4 biosensors, 5 biomolecular recognition devices and molecular transporters, 6 artificial water channels, 7 cancer therapy 8,9 and photoacoustic molecular imaging. 10 Because transitional metals are often used as catalysts during CNT synthesis, 11 it is unavoidable that as-received CNTs are contaminated by catalyst residues. 12 The catalyst precursor (such as iron carbonyl) decomposes, and nanometer-sized metal particles form from the decomposition products. Therefore,

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“…One of the pathophysiological mechanisms of Co is postulated to be its ability to produce ROS (27,28,(31)(32)(33)41). It has been reported that cadmium-mediated accumulation of ubiquitinated proteins is enhanced by its oxidative stress (8).…”

Section: Ros Are Not Involved In Cocl 2 -Induced Accumulation Of Ubiqmentioning

confidence: 99%

Inhibition of proteasome activity is involved in cobalt-induced apoptosis of human alveolar macrophages

Araya

Maruyama

Inoue

et al. 2002

American Journal of Physiology-Lung Cellular and Molecular Phys

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Inhalation of particulate cobalt has been known to induce interstitial lung disease. There is growing evidence that apoptosis plays a crucial role in physiological and pathological settings and that the ubiquitin-proteasome system is involved in the regulation of apoptosis. Cadmium, the same transitional heavy metal as cobalt, has been reported to accumulate ubiquitinated proteins in neuronal cells. On the basis of these findings, we hypothesized that cobalt would induce apoptosis in the lung by disturbance of the ubiquitin-proteasome pathway. To evaluate this, we exposed U-937 cells and human alveolar macrophages (AMs) to cobalt chloride (CoCl2) and examined their apoptosis by DNA fragmentation assay, 4′,6-diamidino-2′-phenylindol dihydrochloride staining, and Western blot analysis. CoCl2 induced apoptosis and accumulated ubiquitinated proteins. Exposure to CoCl2 inhibited proteasome activity in U-937 cells. Cobalt-induced apoptosis was mediated via mitochondrial pathway because CoCl2 released cytochrome c from mitochondria. These results suggest that cobalt-induced apoptosis of AMs may be one of the mechanisms for cobalt-induced lung injury and that the accumulation of ubiquitinated proteins might be involved in this apoptotic process.

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Cobalt-mediated generation of reactive oxygen species and its possible mechanism

Cited by 167 publications

References 27 publications

Highly efficient photocatalytic oxidation of sulfur-containing organic compounds and dyes on TiO2 with dual cocatalysts Pt and RuO2

Highly efficient photocatalytic oxidation of sulfur-containing organic compounds and dyes on TiO2 with dual cocatalysts Pt and RuO2

The contributions of metal impurities and tube structure to the toxicity of carbon nanotube materials

Inhibition of proteasome activity is involved in cobalt-induced apoptosis of human alveolar macrophages

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