In vitro cytotoxicity and genotoxicity studies of titanium dioxide (TiO2) nanoparticles in Chinese hamster lung fibroblast cells

There are increasing safety concerns about the development and abundant use of nanoparticles. The unique physical and chemical characteristics of titanium dioxide (TiO₂) nanoparticles result in different chemical and biological activities compared to their larger micron-sized counterparts, and can subsequently play an important role in influencing toxicity. Therefore, our objective was to investigate the cytotoxicity and genotoxicity of commercially available TiO₂ nanoparticles with respect to their selected physicochemical properties, as well as the role of surface coating of these nanoparticles. While all types of tested TiO₂ samples decrease cell viability in a mass-based concentration- and size-dependent manner, the polyacrylate-coated nano-TiO₂ product was only cytotoxic at higher concentrations. A similar pattern of response was observed for induction of apoptosis/necrosis, and no DNA damage was detected in the polyacrylate-coated nano-TiO₂ model. Given the increasing production of TiO₂ nanoparticles, toxicological studies should take into account the physiochemical properties of these nanoparticles that may help researchers to develop new nanoparticles with minimum toxicity.     

Genotoxic and cytotoxic potential of titanium dioxide (TiO2) nanoparticles on fish cells in vitro

Intrinsic genotoxic and cytotoxic potential of titanium dioxide (TiO2) engineered nanoparticles (ENPs) were evaluated in a metabolically competent, established fish cell line derived from rainbow trout (Oncorhyncus mykiss) gonadal tissue (i.e. RTG-2 cells). Prior to evaluation of the toxic potential, mean size of the ENPs was determined using transmission electron microscopy (TEM). As a prerequisite, an extensive characterisation of the ENPs was carried out following sonication which enabled the synthesis of an efficient dosing strategy for the cells in which exposure in phosphate buffered saline (PBS) gave an optimal agglomeration effects compared to distilled water (H2O) and minimal essential media (MEM). Interaction of the ENPs with cells under scanning electron microscope (SEM) was also studied. The genotoxic and cytotoxic potential of the ENPs were determined either alone or in combination with ultraviolet radiation (i.e. UVA). Whilst genotoxic potential was determined by evaluating DNA strand breaks using single cell gel electrophoresis (SCGE) or the comet assay and induction of cytogenetic damage using cytokinesis-blocked micronucleus (MN) assay, cytotoxicity was determined by measuring the retention of supra vital stain, neutral red, by the lysosomes using the neutral red retention (NRR) assay. In addition, while performing the comet assay, lesion specific bacterial endonuclease, formamidopyrimidine DNA glycosylase (Fpg), which recognises oxidised purine bases, was used to determine oxidative DNA damage. The results suggested that the highest concentration of the ENPs (i.e. 50 microg ml(-1)) did not produce elevations in DNA damage over 4 h (comet assay), 24 h (modified comet assay) or 48 h (MN assay) exposures in the absence of UVA irradiation, although there was a significant reduction in lysosomal integrity over 24 h exposure (NRR assay). The induction of MN did not show any enhanced levels as a function of ENP concentration. A significantly increased level of strand breaks was observed in combination with UVA (3 kJ m(-2)). In general, the NRR assay suggested elevated levels of cytotoxicity when the UVA exposure was carried out with MEM compared to PBS, although both showed an increase when in combination with the highest concentration of ENPs (i.e. 50 microg ml(-1)). Overall, the study emphasises the need for adoption of an holistic approach while evaluating the potential toxic effects of ENPs in which appropriate measures should be taken to avoid agglomeration or aggregation to facilitate efficient cellular uptake to evaluate potential biological responses.     

Oxidative stress and apoptosis induced by titanium dioxide nanoparticles in cultured BEAS-2B cells

As the applications of industrial nanoparticles are being developed, the concerns on the environmental health are increasing. Cytotoxicities of titanium dioxide nanoparticles of different concentrations (5, 10, 20 and 40mug/ml) were evaluated in this study using a cultured human bronchial epithelial cell line, BEAS-2B. Exposure of the cultured cells to nanoparticles led to cell death, reactive oxygen species (ROS) increase, reduced glutathione (GSH) decrease, and the induction of oxidative stress-related genes such as heme oxygenase-1, thioredoxin reductase, glutathione-S-transferase, catalase, and a hypoxia inducible gene. The ROS increase by titanium dioxide nanoparticles triggered the activation of cytosolic caspase-3 and chromatin condensation, which means that titanium dioxide nanoparticles exert cytotoxicity by an apoptotic process. Furthermore, the expressions of inflammation-related genes such as interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), TNF-a, and C-X-C motif ligand 2 (CXCL2) were also elevated. The induction of IL-8 by titanium dioxide nanoparticles was inhibited by the pre-treatment with SB203580 and PD98059, which means that the IL-8 was induced through p38 mitogen-acitvated protein kinase (MAPK) pathway and/or extracellular signal (ERK) pathway. Uptake of the nanoparticles into the cultured cells was observed and titanium dioxide nanoparticles seemed to penetrate into the cytoplasm and locate in the peri-region of the nucleus as aggregated particles, which may induce direct interactions between the particles and cellular molecules, to cause adverse biological responses.     

Size influences the cytotoxicity of poly (lactic-co-glycolic acid) (PLGA) and titanium dioxide (TiO2) nanoparticles

The aim of this study is to uncover the size influence of poly (lactic-co-glycolic acid) (PLGA) and titanium dioxide (TiO₂) nanoparticles on their potential cytotoxicity. PLGA and TiO₂ nanoparticles of three different sizes were thoroughly characterized before in vitro cytotoxic tests which included viability, generation of reactive oxygen species (ROS), mitochondrial depolarization, integrity of plasma membrane, intracellular calcium influx and cytokine release. Size-dependent cytotoxic effect was observed in both RAW264.7 cells and BEAS-2B cells after cells were incubated with PLGA or TiO₂ nanoparticles for 24 h. Although PLGA nanoparticles did not trigger significantly lethal toxicity up to a concentration of 300 μg/ml, the TNF-α release after the stimulation of PLGA nanoparticles should not be ignored especially in clinical applications. Relatively more toxic TiO₂ nanoparticles triggered cell death, ROS generation, mitochondrial depolarization, plasma membrane damage, intracellular calcium concentration increase and size-dependent TNF-α release, especially at a concentration higher than 100 μg/ml. These cytotoxic effects could be due to the size-dependent interaction between nanoparticles and biomolecules, as smaller particles tend to adsorb more biomolecules. In summary, we demonstrated that the ability of protein adsorption could be an important paradigm to predict the in vitro cytotoxicity of nanoparticles, especially for low toxic nanomaterials such as PLGA and TiO₂ nanoparticles.     

Application of titanium dioxide (TiO2) nanoparticles in cancer therapies

Abstract

Cancer is one of the most common diseases all over the world; many people suffer from diverse types of cancer. However, currently there is no exact cure or therapy developed for cancer. On the other hand, nanoparticles are defined as microscopic particles that have dimensions less than 100?nm and they are known for their usage in health sciences and medicine, however a few harmful effects on different animal cells. Therefore, researchers began to use nanoparticles for cancer therapies and to develop new methods for much more effective therapies. Nanoparticles in cancer studies are commonly used in photodynamic therapy (PDT) and sonodynamic therapy (SDT) as a sensitising agent, in computed tomography imaging (CT) and radiation therapy as an enhancement agent, in dual-mode image contrast and enhancement therapy as an image contrast agent. Titanium dioxide nanoparticles (TiO₂ NPs) are known as commonly used nanoparticles in medical applications and hence in cancer studies. They are used in PDT, SDT and drug delivery systems. As cancer continues to affect people, new therapeutics and therapies will be developed and nanotechnology for this aim will be an important approach for the researchers.     

Activation of human neutrophils by titanium dioxide (TiO2) nanoparticles

This paper describes the in vitro effects of titanium dioxide (TiO₂) nanoparticles (NPs) upon human neutrophils. Kinetic experiments revealed no cell necrosis after 24 h of treatment with TiO₂ (0–100 μg/ml). In contrast, TiO₂-induced change in cellular morphology in a concentration-dependent manner in neutrophils over time, indicating its potential to activate these cells. To further support this, we demonstrated that TiO₂ markedly and rapidly induced tyrosine phosphorylation events, including phosphorylation of two key enzymes, p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases-1/2 (Erk-1/2). We also determined the effects of TiO₂ on two neutrophil functions requiring a longer exposure period between NPs and cells: apoptosis and cytokine production. Interestingly, at concentrations ⩾20 μg/ml, TiO₂ inhibited neutrophil apoptosis in a concentration-dependent manner after 24 h of treatment. Supernatants from TiO₂-induced neutrophils were harvested after 24 h and tested for the presence of 36 different analytes (cytokines, chemokines) using an antibody array assay. TiO₂ treatment increased production of 13 (36%) analytes, including IL-8, which exhibited the greatest increase (∼16 × control cell levels). The increased production of IL-8 was confirmed by ELISA. We conclude that TiO₂ exerts important neutrophil agonistic properties in vitro.     

Cytotoxic,genotoxic and the hemolytic effect of titanium dioxide (TiO2) nanoparticles on human erythrocyte and lymphocyte cells in vitro

With the increasing clinical use of titanium dioxide (TiO₂) nanoparticles, a better understanding of their safety in the blood stream is required. The present study evaluates the toxic effect of commercially available TiO₂ nanoparticles (~100 nm) using a battery of cytotoxic, genotoxic, hemolytic and morphological parameters. The cytotoxic effects of TiO₂ nanoparticles in human lymphocyte cells were studied with respect to membrane damage, mitochondrial function, metabolic activity and lysosomal membrane stability. Genotoxicity in lymphocyte cells was quantitated using a comet assay. The mode of cell death (apoptosis/necrosis) was evaluated using PI/Annexin V staining. TiO₂ nanoparticles were also evaluated for their hemolytic properties, osmotic fragility and interaction with hemoglobin. Human erythrocyte cells were studied for morphological alterations using atomic force microscopy (AFM). Results suggest that the particles could induce a significant reduction in mitochondrial dehydrogenase activity in human lymphocyte cells. Membrane integrity remained unaffected by nanoparticle treatment. DNA damage and apoptosis were induced by TiO₂ nanoparticles in a dose‐dependent manner. A study on human erythrocyte cells revealed a hemolytic property of TiO₂ nanoparticles characterized by spherocytosis and echinocytosis. Spectral analysis revealed a hemoglobin TiO₂ nanoparticle interaction. Our in vitro study results suggest that commercially available blood contacting nanoparticles (TiO₂ nanoparticle) should be carefully evaluated for their toxic potential. Copyright © 2013 John Wiley & Sons, Ltd.     

ROS-mediated genotoxicity induced by titanium dioxide nanoparticles in human epidermal cells

Titanium dioxide nanoparticles (TiO₂ NPs) are among the top five NPs used in consumer products, paints and pharmaceutical preparations. Since, exposure to such nanoparticles is mainly through the skin and inhalation, the present study was conducted in the human epidermal cells (A431). A mild cytotoxic response of TiO₂ NPs was observed as evident by the MTT and NR uptake assays after 48 h of exposure. However, a statistically significant (p < 0.05) induction in the DNA damage was observed by the Fpg-modified Comet assay in cells exposed to 0.8 μg/ml TiO₂ NPs (2.20 ± 0.26 vs. control 1.24 ± 0.04) and higher concentrations for 6 h. A significant (p < 0.05) induction in micronucleus formation was also observed at the above concentration (14.67 ± 1.20 vs. control 9.33 ± 1.00). TiO₂ NPs elicited a significant (p < 0.05) reduction in glutathione (15.76%) with a concomitant increase in lipid hydroperoxide (60.51%; p < 0.05) and reactive oxygen species (ROS) generation (49.2%; p < 0.05) after 6 h exposure. Our data demonstrate that TiO₂ NPs have a mild cytotoxic potential. However, they induce ROS and oxidative stress leading to oxidative DNA damage and micronucleus formation, a probable mechanism of genotoxicity. This is perhaps the first study on human skin cells demonstrating the cytotoxic and genotoxic potential of TiO₂ NPs.     

Influence of silver and titanium dioxide nanoparticles on in vitro blood-brain barrier permeability

An in vitro blood-brain barrier (BBB) model being composed of co-culture with endothelial (bEnd.3) and astrocyte-like (ALT) cells was established to evaluate the toxicity and permeability of Ag nanoparticles (AgNPs; 8 nm) and TiO₂ nanoparticles (TiO₂NPs; 6 nm and 35 nm) in normal and inflammatory central nervous system. Lipopolysaccharide (LPS) was pre-treated to simulate the inflammatory responses. Both AgNPs and Ag ions can decrease transendothelial electrical resistance (TEER) value, and cause discontinuous tight junction proteins (claudin-5 and zonula occludens-1) of BBB. However, only the Ag ions induced inflammatory cytokines to release, and had less cell-to-cell permeability than AgNPs, which indicated that the toxicity of AgNPs was distinct from Ag ions. LPS itself disrupted BBB, while co-treatment with AgNPs and LPS dramatically enhanced the disruption and permeability coefficient. On the other hand, TiO₂NPs exposure increased BBB penetration by size, and disrupted tight junction proteins without size dependence, and many of TiO₂NPs accumulated in the endothelial cells were observed. This study provided the new insight of toxic potency of AgNPs and TiO₂NPs in BBB.     

Tissue distribution and clearance of intravenously administered titanium dioxide (TiO2) nanoparticles

The organ-tissue distribution and clearance of Degussa P25 TiO₂ nanoparticles were determined after intravenous administration to rats (0.95 mg/kg bodyweight) using an inductively coupled plasma sector field mass spectrometer. The detection limits of Ti analysis, 0.54 and 1.4 ng/mL for blood and urine and 0.35–2.0 ng/g tissue for several organ tissues, enabled determination of tissue distribution and clearance for organs in which Ti content could not be previously determined due to low concentrations. Blood concentrations of TiO₂ were 420 and 19 ng/mL at 5 and 15 min after administration, which were equivalent of only 2.8% and 0.13% of the administration dose, respectively. At 6 h, 94%, 2.0%, 0.17%, 0.023%, 0.014% and 0.026% of administered TiO₂ was found in the liver, spleen, lung, kidney, heart and blood, respectively. Liver and spleen TiO₂ burden was significantly higher in the administration than control group (p < 0.01) and did not decrease up to 30 days after administration, while TiO₂ burden in the lung, kidney, heart and blood decreased over time. A two-step decay model was more suitable than a one-step decay model for the decay curves of pulmonary TiO₂ burden but did not improve fitting to the decay curves of kidney TiO₂ burden. No translocation to the brain was confirmed at a lower detection limit than was applied in previous studies. Ti content in faeces and urine in the TiO₂ administration group did not differ from that in the control group.     

Beneficial effects of quercetin on oxidative stress in liver and kidney induced by titanium dioxide (TiO2) nanoparticles in rats

Abstract

TiO₂ nanoparticles used as vectors for the delivery of drugs have shown greater effectiveness. However, TiO₂ nanoparticles can cause oxidative stress in liver and kidney, so we analyzed if a previous or simultaneous quercetin treatment could counteract this in rats. Five groups of male Wistar rats (200–250?g) were included: (1) healthy controls, (2) TiO₂ group, (3) quercetin group, (4) preventive group: quercetin for 5 days prior to exposure of TiO₂, and (5) therapeutic group: TiO₂ (5?mg/kg, i.v.) plus quercetin single dose for 5 days (5?mg/kg/day, i.p.). Hepatic and renal function tests were made. Five animals from each group were sacrificed (0, 14 and 28 days), and liver and kidney tissue were obtained. Malondialdehyde (MDA), reduced/oxidized glutathione, and activity of glutathione peroxidase/reductase were measured, as well as the level of gene expression by q-PCR. There were no significant changes in serum ALT and AST activities. More damage was observed at 14 versus 28 days, because TiO₂ was excreted in urine. Quercetin indeed showed a renal protective effect by increasing glutathione reductase and peroxidase levels and reducing MDA levels. On the other hand, TiO₂ liver damage was less pronounced with quercetin as therapeutic treatment. TiO₂ induces significantly the glutathione reductase expression and it can be down-regulated by quercetin. Biochemical tests in serum and urine showed a better effect of quercetin administered in the therapeutic group. Care should be taken with the dose and time of administration of quercetin, because this antioxidant could also have a pro-oxidant effect.     

Antioxidant imbalance and genotoxicity detected in fish induced by titanium dioxide nanoparticles (NpTiO2) and inorganic lead (PbII)

Titanium dioxide nanoparticles (NpTiO₂) are the most widely-used nanoparticle type and the adsorption of metals such as lead (PbII) onto their surface is a major source of concern to scientists. This study evaluated the effects of the associated exposure to both types of contaminant, i.e., lead (a known genotoxic metal) and NpTiO₂, in a freshwater fish (Astyanax serratus) through intraperitoneal injection for an acute assay of 96 h. The effects of this exposure were evaluated using the comet assay, DNA diffusion assay and piscine micronucleus test, as well as the quantification of antioxidant enzymes (SOD, CAT, and GST) and metallothioneins. Our findings indicate that co-exposure of PbII with NpTiO₂ can provoke ROS imbalances, leading to DNA damage in the blood and liver tissue of A. serratus, as well as modifying erythropoiesis in this species, inducing necrosis and changing the nuclear morphology of the erythrocytes.     

Tissue-specific genotoxicity and antioxidant imbalance of titanium dioxide nanoparticles (NPTiO2) and inorganic lead (PbII) in a neotropical fish species

The aquatic environment is the major recipient of wastes containing nanoparticles and other contaminants. Titanium dioxide nanoparticles (NPTiO₂) are one of the most produced and used nanoparticle worldwide. This study investigated the toxicity of NPTiO₂, as well as the toxicity interaction between NPTiO₂ and lead (Pb), in response to genetic and biochemical biomarkers using freshwater fish Rhamdia quelen, as an animal model. The results showed genotoxicity in blood and kidney tissues. No effect of NPTiO₂ alone or in co-exposure with Pb on liver genotoxicity were observed. Alterations in the antioxidant hepatic enzymes activities, as well as alterations in glutathione levels indicated that NPTiO₂ alone or in co-exposure with Pb can cause antioxidant imbalance. The lipid peroxidation was also raised after exposure to NPTiO₂. In general, the results of this study indicated that both NPTiO₂ alone and their co-exposure with Pb are capable of producing significant toxic effects in short-term exposure.     

Oxidative stress and apoptosis induced by nanosized titanium dioxide in PC12 cells

The nanosized titanium dioxide (nano-TiO₂) is produced abundantly and used widely in the chemical, electrical/electronic and energy industries because of its special photovoltaic and photocatalytic activities. Past reports have shown that the nano-TiO₂ can enter into the human body through different routes such as inhalation, ingestion, dermal penetration and injection. The effects of nano-TiO₂ on different organs are currently being investigated and the concerns on its large scale applications such as sunscreen, etc. indeed become more interesting for us to investigate and to find the possible right answers for right doses for a safer application. In this research, the cytotoxicity of the nano-TiO₂ was investigated in PC12 cells, a cell line used as a model in vitro for the brain neurons research. While the PC12 cells were treated with different concentrations of nano-TiO₂ (1, 10, 50 and 100 μg/ml), the viability of cells was significantly decreased in the periods of 6, 12, 24 and 48 h, showing a significant dose effect and time-dependent manner. Meanwhile, the flow cytometric assay gave indication that the nano-TiO₂ induced intracellular accumulation of reactive oxygen species (ROS) and the apoptosis of PC12 cells with the increasing concentration of nano-TiO₂. Interestingly, pretreatment of N-(mercaptopropionyl)-glycine (N-MPG), known as a type of ROS scavenger formulations, could somehow inhibit PC12 apoptosis induced by the nano-TiO₂. These results might have revealed a key mechanism in PC12 apoptosis under the effect of the nano-TiO₂ solutions.     

Cytotoxicity and genotoxicity of titanium dioxide nanoparticles in UVA-irradiated normal peripheral blood lymphocytes

The phototoxicity of ultraviolet A irradiation (UVA) can be enhanced by photosensitizing agents, such as titanium dioxide nanoparticles (100 nm in diameter, "normal-TiO?"). Nano-TiO? treatment in the absence of UVA caused a slight decrease in cell viability, but in the presence of UVA, it caused a significant decrease in cell viability. In the presence of UVA, nano-TiO? also significantly increased the percentage of the cell population in the sub-G? phase, induced activation of the proapoptotic proteins, caspase-9, caspase-3, and poly(ADP)ribose polymerase, significantly increased the production of reactive oxygen species (ROS), and induced the loss of the mitochondrial membrane potential (MMP), suggesting that UVA and nano-TiO? synergistically promoted apoptosis via a mitochondrial pathway. In the presence of UVA, but not in its absence, nano-TiO? treatment also caused a significant increase in DNA damage. Normal-TiO? used at the same concentrations did not cause DNA damage, induce ROS generation, trigger mitochondrial membrane depolarization, or increase apoptotic cell death, regardless of UVA exposure. Taken together, these results suggest that nano-TiO? and UVA synergistically promote rapid ROS generation and MMP collapse, triggering apoptosis. Additionally, they show that small TiO? particles are more phototoxic than larger ones.     

Using physiologically based pharmacokinetic (PBPK) modeling for dietary risk assessment of titanium dioxide (TiO2) nanoparticles

Abstract

Nano-sized titanium dioxide particles (nano-TiO₂) can be found in a large number of foods and consumer products, such as cosmetics and toothpaste, thus, consumer exposure occurs via multiple sources, possibly involving different exposure routes. In order to determine the disposition of nano-TiO₂ particles that are taken up, a physiologically based pharmacokinetic (PBPK) model was developed. High priority was placed on limiting the number of parameters to match the number of underlying data points (hence to avoid overparameterization), but still reflecting available mechanistic information on the toxicokinetics of nano-TiO₂. To this end, the biodistribution of nano-TiO₂ was modeled based on their ability to cross the capillary wall of the organs and to be phagocytosed in the mononuclear phagocyte system (MPS). The model’s predictive power was evaluated by comparing simulated organ levels to experimentally assessed organ levels of independent in vivo studies. The results of our PBPK model indicate that: (1) within the application domain of the PBPK model from 15 to 150?nm, the size and crystalline structure of the particles had a minor influence on the biodistribution; and (2) at high internal exposure the particles agglomerate in vivo and are subsequently taken up by macrophages in the MPS. Furthermore, we also give an example on how the PBPK model may be used for risk assessment. For this purpose, the daily dietary intake of nano-TiO₂ was calculated for the German population. The PBPK model was then used to convert this chronic external exposure into internal titanium levels for each organ.     

Assessment of the in vitro genotoxicity of TiO2 nanoparticles in a regulatory context

A review of in vitro genotoxicity studies on titanium dioxide nanoparticles (TiO₂-NPs) published between 2010 and 2016 was performed by France in the framework of the CLP Regulation 1272/2008/EC. Neither the few in vivo studies of low quality nor the larger number of acceptable in vitro studies available for genotoxicity allowed France to conclude on the genotoxicity of TiO₂-NPs. Based on this work, it was decided to compare the acceptable in vitro studies to understand the reasons for the diverging results observed, such as the materials tested or of the protocols used and their inherent interferences. The systematic review performed on in vitro genotoxicity data for TiO₂-NPs was then restricted to studies with the highest level of confidence among studies following OECD guidelines and the largely applied comet assay. Indeed, the aim of this article is to understand why, even if judged of good quality, the 36 publications selected and analyzed did not lead to a clear picture. Some recommendations to be taken into account before performing new in vitro genotoxicity assays for insoluble particles such as TiO₂-NPs are proposed. Although secondary genotoxic effects consequent to oxidative stress seem to be the major mechanism responsible for the genotoxicity of TiO₂-NPs reported in some studies, primary genotoxic effects cannot be excluded. Further studies are needed to clarify the exact mode of action of TiO₂-NPs and to highlight which physicochemical properties lead to their genotoxicity in vitro to ultimately identify a specific combination of parameters that could represent a risk in vivo.     

Titanium dioxide nanoparticles induced cytotoxicity, oxidative stress and DNA damage in human amnion epithelial (WISH) cells

Titanium dioxide nanoparticles (TiO(2)-NPs) induced cytotoxicity and DNA damage have been investigated using human amnion epithelial (WISH) cells, as an in vitro model for nanotoxicity assessment. Crystalline, polyhedral rutile TiO(2)-NPs were synthesized and characterized using X-ray diffraction (XRD), UV-Visible spectroscopy, Fourier transform infra red (FTIR) spectroscopy, and transmission electron microscopic (TEM) analyses. The neutral red uptake (NRU) and [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assays revealed the concentration dependent cytotoxic effects of TiO(2)-NPs (30.6nm) in concentration range of 0.625-10μg/ml. Cells exposed to TiO(2)-NPs (10μg/ml) exhibited significant reduction (46.3% and 34.6%; p<0.05) in catalase activity and glutathione (GSH) level, respectively. Treated cells showed 1.87-fold increase in intracellular reactive oxygen species (ROS) generation and 7.3% (p<0.01) increase in G(2)/M cell cycle arrest, as compared to the untreated control. TiO(2)-NPs treated cells also demonstrated the formation of DNA double strand breaks with 14.6-fold (p<0.05) increase in Olive tail moment (OTM) value at 20μg/ml concentration, vis-à-vis untreated control, under neutral comet assay conditions. Thus, the reduction in cell viability, morphological alterations, compromised antioxidant system, intracellular ROS production, and significant DNA damage in TiO(2)-NPs exposed cells signify the potential of these NPs to induce cyto- and genotoxicity in cultured WISH cells.     

Oxidative stress,genotoxicity and cytotoxicity of 1-methyl-3-octylimidazolium chloride on Paramisgurnus dabryanus

This study evaluated the toxicity of 1-methyl-3-octylimidazolium chloride ([C₈mim]Cl) on Paramisgurnus dabryanus by enzyme analysis, comet assay, and apoptosis analysis. The study showed that [C₈mim]Cl had an obvious toxic effect inducing oxidative stress, genotoxicity, and cytotoxicity to fish liver cells. [C₈mim]Cl also induced changes in the activities of superoxide dismutase and catalase, and the glutathione content and malondialdehyde level in fish exposed at 20–80 mg L⁻¹. With increased exposure concentration and time, the four antioxidant enzyme activities, three different comet parameters and apoptosis rates of tested cells were significantly increased, with significant differences (P < 0.05 or P < 0.01) observed between control group and each treatment group. This study shows that [C₈mim]Cl could be a threat to aquatic organism health when accidentally released into aquatic ecosystems.