Oxidative stress contributes to silica nanoparticle-induced cytotoxicity in human embryonic kidney cells

Evaluation of oxidative stress and anti-oxidant status in rat serum following exposure of carbon nanotubes

The aim of the present study was to evaluate the oxidative stress and anti-oxidant status in rat serum following intra-tracheal instillation of multi wall carbon nanotubes (MWCNT). The lungs of rats were intra-tracheally instilled with (single dose of) Phosphate-buffered saline (PBS)+1% of Tween 80 (Solvent Control) or MWCNT or carbonyl Iron (negative control) or quartz particles (positive control) at a dose of 0.2, 1 and 5 mg/kg body weight. Following exposure, the blood samples were collected at 1, 7, 30 and 90 days of post instillation of nanoparticles and different parameters were estimated to assess the oxidative stress induced by the instillation of MWCNT. Exposure of MWCNT to rats produced a significant (p<0.05) dose dependent reduction of blood total anti-oxidant capacity, glutathione, superoxide dismutase, catalase activity and increased lipid peroxidation product, (Malondialdehyde) levels than PBS+1% Tween 80 control group. This reduction in the total anti-oxidant capacity in nanotubes exposed rats indicates the reduction in anti-oxidant deference mechanisms due to the instillation of MWCNT. These results indicate that, exposure of multi wall carbon nanotubes induces oxidative stress by reducing the total anti-oxidant capacity in rats. The findings suggest possible occupational health hazard in chronic exposures.

Endothelial cells dysfunction induced by silica nanoparticles through oxidative stress via JNK/P53 and NF-kappaB pathways

Drug carriers are generally introduced into the body intravenously and directly exposed to endothelial cells. Silica nanoparticles could be promising delivery vehicles for drug targeting or gene therapy. However, few studies have been undertaken to determine the biological behavior of silica nanoparticles on endothelial cells. Here we measured reactive oxygen species (ROS) generation, apoptosis and necrosis, proinflammatory and prothrombic properties and the levels of the apoptotic signaling proteins and the transcription factors in human umbilical vein endothelial cells (HUVECs) after exposure to silica nanoparticles of different concentrations (25, 50, 100, and 200 microg/mL) for 24h. The results showed that silica nanoparticles, ranging from 50 microg/mL to 200 microg/mL, markedly induced ROS production, mitochondrial depolarization and apoptosis in HUVECs. At the highest concentration, the necrotic rate, LDH leakage, the expression of CD54 and CD62E, and the release of TF, IL-6, IL-8 and MCP-1 were significantly increased. Silica nanoparticles also activated c-Jun N-terminal kinase (JNK), c-Jun, p53, caspase-3 and NF-kappaB, increased Bax expression and suppressed Bcl-2 protein. Moreover, inhibition of ROS attenuated silica nanoparticles-induced apoptosis and inflammation and the activation of JNK, c-Jun, p53 and NF-kappaB. In summary, our findings demonstrated that silica nanoparticles could induce dysfunction of endothelial cells through oxidative stress via JNK, p53 and NF-kappaB pathways, suggesting that exposure to silica nanoparticles may be a significant risk for the development of cardiovascular diseases such as atherosclerosis and thrombus.

Nanotoxicity of pure silica mediated through oxidant generation rather than glutathione depletion in human lung epithelial cells

Though, oxidative stress has been implicated in silica nanoparticles induced toxicity both in vitro and in vivo, but no similarities exist regarding dose-response relationship. This discrepancy may, partly, be due to associated impurities of trace metals that may present in varying amounts. Here, cytotoxicity and oxidative stress parameters of two sizes (10 nm and 80 nm) of pure silica nanoparticles was determined in human lung epithelial cells (A549 cells). Both sizes of silica nanoparticles induced dose-dependent cytotoxicity as measured by MTT [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and lactate dehydrogenase (LDH) assays. Silica nanoparticles were also found to induce oxidative stress in dose-dependent manner indicated by induction of reactive oxygen species (ROS) generation, and membrane lipid peroxidation (LPO). However, both sizes of silica nanoparticles had little effect on intracellular glutathione (GSH) level and the activities of glutathione metabolizing enzymes; glutathione reductase (GR) and glutathione peroxidase (GPx). Buthionine-[S,R]-sulfoximine (BSO) plus silica nanoparticles did not result in significant GSH depletion than that caused by BSO alone nor N-acetyl cysteine (NAC) afforded significant protection from ROS and LPO induced by silica nanoparticles. The rather unaltered level of GSH is also supported by finding no appreciable alteration in the level of GR and GPx. Our data suggest that the silica nanoparticles exert toxicity in A549 cells through the oxidant generation (ROS and LPO) rather than the depletion of GSH.

Induction of oxidative stress and cytotoxicity by carbon nanomaterials is dependent on physical properties

In this study, we investigated the mechanisms involved in multi-wall carbon particles/nanomaterials (MWCNM) induced cytotoxicity using human embryonic kidney (HEK293) cells and to assess the effect of physicochemical properties on the cytotoxicity and oxidative stress induced by the carbon nanomaterials (CNM). To elucidate the possible mechanisms of CNM-induced cytotoxicity, cell viability (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide [MTT assay]), cell membrane damage (lactate dehydrogenase enzyme [LDH] assay), reduced glutathione (GSH), interleukin-8 (IL-8) and lipid peroxidation levels were quantitatively assessed under carbon nanomaterials exposed (48 h) conditions. Exposure of different sizes of four CNM at dosage levels between 3 and 300 μg/mL decreased cell viability in a concentration- and size-dependent manner. Exposure of CNM (10-100 μg/mL) to HEK cells resulted in size-, surface area- and concentration-dependent cell membrane damage, increased production of IL-8, increased thiobarbituric acid reactive substances (TBARS) and decreased intracellular glutathione levels. In summary, the physical properties of carbon nanoparticles may alter the CNM-induced concentration-dependent cytotoxicity and oxidative stress.

Biocompatibility of polymer grafted core/shell iron/carbon nanoparticles

For biomedical applications, emerging nanostructures requires stringent evaluations for their biocompatibility. Core/shell iron/carbon nanoparticles (Fe@CNPs) are nanomaterials that have potential applications in magnetic resonance imaging (MRI), magnetic hyperthermia and drug delivery. However, their interactions with biological systems are totally unknown. To evaluate their potential cellular perturbations and explore the relationships between their biocompatibility and surface chemistry, we synthesized polymer grafted Fe@CNPs with diverse chemistry modifications on surface and investigated their dynamic cellular responses, cell uptake, oxidative stress and their effects on cell apoptosis and cell cycle. The results show that biocompatibility of Fe@CNPs is both surface chemistry dependent and cell type specific. Except for the carboxyl modified Fe@CNPs, all other Fe@CNPs present low toxicity and can be used for further functionalization and in a wide range of biomedical applications.

Multi wall carbon nanotubes induce oxidative stress and cytotoxicity in human embryonic kidney (HEK293) cells

The present study was aimed at evaluating the potential toxicity and the general mechanism involved in multi wall carbon nanotubes (MWCNT)-induced cytotoxicity using human embryonic kidney cell line (HEK293) cells. Two multi wall carbon nanotubes (coded as MWCNT1, size: 90-150nm and MWCNT2, size: 60-80nm) used in this study are MWCNT1 (produced by the electric arc method and size of the nanotubes was 90-150nm) and MWCNT2 (produced by the chemical vapor deposition method with size of 60-80nm). To elucidate the possible mechanisms of MWCNT induced cytotoxicity, cell viability, mitochondrial function (MTT assay), cell membrane damage (LDH assay), reduced glutathione (GSH), interleukin-8 (IL-8) and lipid peroxidation levels were quantitatively assessed under carbon nanotubes exposed (48h) conditions. Exposure of different sizes of two carbon nanotubes at dosage levels between 3 and 300mug/ml decreased cell viability in a concentration dependent manner. The IC(50) values (concentration of nanoparticles to induce 50% cell mortality) of two (MWCNT1, MWCNT2) nanoparticles were found as 42.10 and 36.95mug/ml. Exposure of MWCNT (10-100mug/ml) to HEK cells resulted in concentration dependent cell membrane damage (as indicated by the increased levels of LDH), increased production of IL-8, increased TBARS and decreased intracellular glutathione levels. The cytotoxicity and oxidative stress was significantly more in MWCNT2 exposed cells than MWCNT1. In summary, exposure of carbon nanotubes resulted in a concentration dependent cytotoxicity in cultured HEK293 cells that was associated with increased oxidative stress.