Endothelial cell activation,oxidative stress and inflammation induced by a panel of metal-based nanomaterials

Abstract

The importance of composition, size, crystal structure, charge and coating of metal-based nanomaterials (NMs) were evaluated in human umbilical vein endothelial cells (HUVECs) and/or THP-1 monocytic cells. Biomarkers of oxidative stress and inflammation were assessed because they are important in the development of cardiovascular diseases. The NMs used were five TiO₂ NMs with different charge, size and crystal structure, coated and uncoated ZnO NMs and Ag which were tested in a wide concentration range. There were major differences between the types of NMs; exposure to ZnO and Ag resulted in cytotoxicity and increased gene expression levels of HMOX1 and IL8. The intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1(VCAM-1) expression were highest in TiO₂ NM-exposed cells. There was increased adhesion of THP-1 monocytic cells onto HUVECs with Ag exposure. None of the NMs increased the intracellular ROS production. There were no major effects of the coating of ZnO NMs. The TiO₂ NMs data on ICAM-1 and VCAM-1 expression suggested that the anatase form was more potent than the rutile form. In addition, the larger TiO₂ NM was more potent than the smaller for gene expression and ICAM-1 and VCAM-1 expression. The toxicological profile of cardiovascular disease-relevant biomarkers depended on composition, size and crystal structure of TiO₂ NMs, whereas the charge on TiO₂ NMs and the coating of ZnO NMs were not associated with differences in toxicological profile.     

Applicability of rat precision-cut lung slices in evaluating nanomaterial cytotoxicity,apoptosis, oxidative stress,and inflammation

The applicability of rat precision-cut lung slices (PCLuS) in detecting nanomaterial (NM) toxicity to the respiratory tract was investigated evaluating sixteen OECD reference NMs (TiO₂, ZnO, CeO₂, SiO₂, Ag, multi-walled carbon nanotubes (MWCNTs)). Upon 24-hour test substance exposure, the PCLuS system was able to detect early events of NM toxicity: total protein, reduction in mitochondrial activity, caspase-3/-7 activation, glutathione depletion/increase, cytokine induction, and histopathological evaluation. Ion shedding NMS (ZnO and Ag) induced severe tissue destruction detected by the loss of total protein. Two anatase TiO₂ NMs, CeO₂ NMs, and two MWCNT caused significant (determined by trend analysis) cytotoxicity in the WST-1 assay. At non-cytotoxic concentrations, different TiO₂ NMs and one MWCNT increased GSH levels, presumably a defense response to reactive oxygen species, and these substances further induced a variety of cytokines. One of the SiO₂ NMs increased caspase-3/-7 activities at non-cytotoxic levels, and one rutile TiO₂ only induced cytokines. Investigating these effects is, however, not sufficient to predict apical effects found in vivo. Reproducibility of test substance measurements was not fully satisfactory, especially in the GSH and cytokine assays. Effects were frequently observed in negative controls pointing to tissue slice vulnerability even though prepared and handled with utmost care. Comparisons of the effects observed in the PCLuS to in vivo effects reveal some concordances for the metal oxide NMs, but less so for the MWCNT. The highest effective dosages, however, exceeded those reported for rat short-term inhalation studies. To become applicable for NM testing, the PCLuS system requires test protocol optimization.     

No evidence of the genotoxic potential of gold,silver, zinc oxide and titanium dioxide nanoparticles in the SOS chromotest

Gold nanoparticles (Au NPs), silver nanoparticles (Ag NPs), zinc oxide nanoparticles (ZnO NPs) and titanium dioxide nanoparticles (TiO₂ NPs) are widely used in cosmetic products such as preservatives, colorants and sunscreens. This study investigated the genotoxicity of Au NPs, Ag NPs, ZnO NPs and TiO₂ NPs using the SOS chromotest with Escherichia coli PQ37. The maximum exposure concentrations for each nanoparticle were 3.23 mg l^–1 for Au NPs, 32.3 mg l^–1 for Ag NPs and 100 mg l^–1 for ZnO NPs and TiO₂ NPs. Additionally, in order to compare the genotoxicity of nanoparticles and corresponding dissolved ions, the ions were assessed in the same way as nanoparticles. The genotoxicity of the titanium ion was not assessed because of the extremely low solubility of TiO₂ NPs. Au NPs, Ag NPs, ZnO NPs, TiO₂ NPs and ions of Au, Ag and Zn, in a range of tested concentrations, exerted no effects in the SOS chromotest, evidenced by maximum IF (IFmax) values of below 1.5 for all chemicals. Owing to the results, nanosized Au NPs, Ag NPs, ZnO NPs, TiO₂ NPs and ions of Au, Ag and Zn are classified as non‐genotoxic on the basis of the SOS chromotest used in this study. To the best of our knowledge, this is the first study to evaluate the genotoxicity of Au NPs, Ag NPs, ZnO NPs and TiO₂ NPs using the SOS chromotest. Copyright © 2012 John Wiley & Sons, Ltd.     

Dietary exposure to titanium dioxide nanoparticles in rainbow trout, (Oncorhynchus mykiss): no effect on growth, but subtle biochemical disturbances in the brain

Our laboratory recently reported gut pathology following incidental ingestion of titanium dioxide nanoparticles (TiO₂ NPs) during aqueous exposures in trout, but there are almost no data on dietary exposure to TiO₂ NPs in fish. The aim of this experiment was to observe the sub-lethal effects of dietary exposure to TiO₂ NPs in juvenile rainbow trout (Oncorhynchus mykiss). Stock solutions of dispersed TiO₂ NPs were prepared by sonication without the use of solvents and applied to a commercial trout diet. Fish were exposed in triplicate to either, control (no added TiO₂), 10, or 100 mg kg⁻¹ TiO₂ NPs diets for 8 weeks followed by a 2 week recovery period where all fish were fed the control diet. TiO₂ NPs had no impact on growth or nutritional performance, and no major disturbances were observed in red or white blood cell counts, haematocrits, whole blood haemoglobin, or plasma Na⁺. Ti accumulation occurred in the gill, gut, liver, brain and spleen during dietary TiO₂ exposure. Notably, some of these organs, especially the brain, did not clear Ti after exposure. The brain also showed disturbances to Cu and Zn levels (statistically significant at weeks 4 and 6; ANOVA or Kruskal–Wallis, P < 0.05) and a 50% inhibition of Na⁺K⁺-ATPase activity during TiO₂ NP exposure. Na⁺K⁺-ATPase activity was unaffected in the gills and intestine. Total glutathione in the gills, intestine, liver and brain were not affected by dietary TiO₂ NPs, but thiobarbituric acid reactive substances (TBARS) showed up to 50% decreases in the gill and intestine. We conclude that TiO₂ NPs behave like other toxic dietary metals where growth rate and haematology can be protected during sub-lethal exposures, but in the case of TiO₂ NPs this may be at the expense of critical organs such as the brain and the spleen.     

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on liver phosphoenolpyruvate carboxykinase (PEPCK) activity, glucose homeostasis and plasma amino acid concentrations in the most TCDD-susceptible and the most TCDD-resistant rat strains

Reduced gluconeogenesis due to decreased activity of key gluconeogenic enzymes in liver, together with feed refusal, has been suggested to play an important role in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced lethality in rats. This study was carried out to further analyse the toxicological significance of reduced gluconeogenesis by comparing dose-responses and time-courses of effects of TCDD on the activity of phosphoenolpyruvate carboxykinase (PEPCK) in liver, liver glycogen concentration as well as plasma concentrations of glucose and amino acids in both genders of TCDD-sensitive Long-Evans (L-E) rats and TCDD-resistant Han/Wistar (H/W) rats. A dose-dependent decrease in PEPCK activity was observed in H/W rats, but in L-E rats the activity was not decreased. However, TCDD impaired the strong increase in liver PEPCK activity observed in pair-fed controls of the L-E strain. Liver glycogen concentrations were severely decreased in L-E rats and moderately in H/W rats. This effect seems to be secondary to reduced feed intake, since a similar decrease was seen in pair-fed controls. Decreases in plasma glucose concentrations were also more profound in L-E rats than in H/W rats, but pair-fed controls were generally less affected. Circulating concentrations of amino acids were markedly increased in TCDD-treated L-E rats, which is likely to reflect increased mobilization of amino acids and their decreased metabolism in liver. Reduction of liver PEPCK activity cannot account for the sensitivity difference of these two strains of rats in terms of mortality. Nevertheless, the response of both strains of TCDD-treated rats regarding gluconeogenesis is different from that seen in pair-fed controls and suggesting that impairment of this pathway contributes to the development of the wasting syndrome. Received: 29 March 1999 / Accepted: 17 May 1999     

Direct and indirect effects of zinc oxide and titanium dioxide nanoparticles on the decomposition of leaf litter in streams

As the production of metallic nanoparticles has grown, it is important to assess their impacts on structural and functional components of ecosystems. We investigated the effects of zinc and titanium nanoparticles on leaf decomposition in freshwater habitats. We hypothesized that nanoparticles would inhibit the growth and activity of microbial communities leading to decreased decomposition rates. We also hypothesized that under natural light, the nanoparticles would produce reactive oxygen species that could potentially accelerate decomposition. In the lab, whole Ficus vasta leaves were placed in containers holding one liter of stream water and exposed to either 0, 1, 10 or 100 mg/L of ZnO or TiO₂ nanoparticles for six weeks (referred to as Exp. 1). We measured leaf mass loss, microbial metabolism, and bacterial density at 2, 4, and 6 weeks. In a second experiment (referred to as Exp. 2), we measured the effects of light and 10 and 100 mg/L ZnO or TiO₂ nanoparticles on leaf mass loss, bacterial density and the bacterial and fungal community diversity over a 2 week period. In Experiment 1, mass loss was significantly reduced at 10 and 100 mg/L after 6 weeks and bacterial density decreased at 100 mg/L. In Experiment 2, there was no effect of ZnO nanoparticles on leaf mass loss, but TiO₂ nanoparticles significantly reduced mass loss in the dark but not in the light. One possible explanation is that release of reactive oxygen species by the TiO₂ nanoparticles in the light may have increased the rate of leaf decomposition. Bacterial and fungal diversity was highest in the dark, but nanoparticles did not reduce overall diversity.

     

The buccal mucosa as a route for TiO2 nanoparticle uptake

Abstract

The oral cavity, although part of the aero-digestive tract, is still neglected in terms of risk assessment with respect to nanoparticle uptake. If nanoparticles enter the oral cavity, either via oral products or inhaled materials, it is not clear whether they rapidly interact with the mucosae or are swallowed. In this study, interactions of three distinct titanium dioxide (TiO₂) particles (i.e. NM 100, NM 101 and NM 105) with oral tissues are presented. Physicochemical properties were addressed in relevant media, and particle penetration was investigated with an ex vivo model using porcine mucosa. To avoid modification of the particle surfaces via labeling, multiphoton microscopy was introduced as an accurate method to detect TiO₂ particles within the tissue. The spatiotemporal aspects of nanoparticle uptake, as well as the intracellular localization in human epithelial cells, were studied and potential toxic effects were evaluated. Although TiO₂ particles formed large aggregates once dispersed in media, 10–50% remained in the nanoscale range, rapidly interacting with the mucus layer and infecting the epithelium. However, differences in the penetration depth were observed depending on the particle characteristics. NM 100 and NM 105 were found in both the upper part and the lower part of the buccal mucosa, while NM 101 (smallest particle sizes) only penetrated the upper parts. Transport studies revealed that TiO₂ nanoparticles were found in vesicles, as well as freely distributed in the cytoplasm. Cell viability/integrity was not affected negatively; however, NM 105 triggered the production of reactive oxygen species. These data clearly suggest that the oral cavity should be considered in further risk assessment studies.     

Ecotoxicological effect of TiO2 nano particles on different soil enzymes and microbial community

TiO₂ nano particles (NPs) are one of the most produced nanoparticles in the world which are increasingly being released in to the soil. Soils are exposed to various level of concentration of TiO₂ NPs, which has raised concern over the adverse influence on soil microbial community, in turn on ecosystem functions. Although, increasing number of studies on ecotoxicological effect of TiO₂ NPs are coming up recently, however, a common conscience has yet to be reached regarding the impact of TiO₂ NPs on soil microbial community and processes. Moreover, very few studies have targeted soil enzymes which are being considered as sensitive indicator of soil health. Therefore, the present study has been carried out to estimate the ecotoxicological effect of various doses of TiO₂ NPs (5, 10, 20, 40, 80, 100 mg kg⁻¹ soil) on different soil enzymes and microbial community structure. Results revealed that soil enzyme activities and microbial biomass had a uniform trend where the value increased up to the dose of 20 mg TiO₂ NPs kg⁻¹ soil and there onwards reduced drastically up to 100 mg TiO₂ NPs kg⁻¹ soil dose. On the contrary, soil respiration and metabolic quotient kept increasing up to 100 mg TiO₂ NPs kg⁻¹ soil dose indicating sub-lethal stress on microbial community. Nevertheless, the structure of microbial community had slightly different trend where the biomass of total phospho lipid fatty acid (PLFA), Gram positive, Gram negative bacteria, fungi, actinomyctetes and anaerobes were found to be increased up to dose of 80 mg TiO₂ NPs kg⁻¹ soil, but, significantly declined at 100 mg TiO₂ NPs kg⁻¹ soil dose. Furthermore, temperature effect on TiO₂ NPs toxicity had exhibited a less negative impact at 40 °C rather than at 25 °C. In addition alteration index (AI3), an integrated indicator of C, N, P cycling of soils as well as a well-documented indicator of soil pollution, has been found to be regulated by soil respiration, clay content, anaerobe and eukaryote for AI3-Acid Phos. and by fungi to bacteria ratio, soil respiration, microbial biomass and Gram positive bacteria for AI3-Alk. Phos. Overall, the study provided valuable information regarding ecotoxicological impact of environmentally relevant concentrations of TiO₂ NPs in clay loam soils as well as improved our perception regarding the impact of NPs on soil functioning.

     

Toxicity of nanoparticles of ZnO, CuO and TiO2 to yeast Saccharomyces cerevisiae

The aim of this study was to evaluate the toxic effect of nanosized ZnO, CuO and TiO₂ to Saccharomyces cerevisiae – a widely used unicellular eukaryotic model organisms in molecular and cell biology. The effect of metal oxide nanoparticles, their bulk forms and respective ionic forms were compared. The bioavailable Zn²⁺ and Cu²⁺ ions in the growth medium were quantified by recombinant microbial sensors.Nano and bulk TiO₂ were not toxic even at 20000 mg/l. Both, nano and bulk ZnO were of comparable toxicity (8-h EC₅₀ 121–134 mg ZnO/l and 24-h EC₅₀ 131–158 mg/l). The toxicity was explained by soluble Zn-ions as proved by the microbial sensor. However, nano CuO was about 60-fold more toxic than bulk CuO: 8-h EC₅₀ were 20.7 and 1297 mg CuO/l and 24-h EC₅₀ were 13.4 and 873 mg/l, respectively. The increase in toxicity of both CuO formulations at 24th hour of growth was due to the increased dissolution of copper ions from CuO over time. Comparison of EC₅₀ values of nano CuO, bulk CuO and Cu²⁺ with bioavailable copper concentrations in the growth medium showed that the solubilized Cu-ions explained only about 50% of the toxicity of both, nano and bulk CuO. To our knowledge, this is the first study that evaluates the toxicity of ZnO, CuO and TiO₂ nanoparticles to S. cerevisiae.     

Cytotoxicity and oxidative DNA damage by nanoparticles in human intestinal Caco-2 cells

Abstract

The use of engineered nanoparticles in the food sector is anticipated to increase dramatically, whereas their potential hazards for the gastrointestinal tract are still largely unknown. We investigated the cytotoxic and DNA-damaging effects of several types of nanoparticles and fine particles relevant as food additives (TiO₂ and SiO₂) or for food packaging (ZnO and MgO) as well as carbon black on human intestinal Caco-2 cells. All particles, except for MgO, were cytotoxic (LDH and WST-1 assay). ZnO, and to lesser extent SiO₂, induced significant DNA damage (Fpg-comet), while SiO₂ and carbon black were the most potent in causing glutathione depletion. DNA damage by TiO₂ was found to depend on sample processing conditions. Interestingly, application of different TiO₂ and ZnO particles revealed no relation between particle surface area and DNA damage. Our results indicate a potential hazard of several food-related nanoparticles which necessitate investigations on the actual exposure in humans.     

Evaluation of cytogenotoxicity and oxidative stress parameters in male Swiss mice co-exposed to titanium dioxide and zinc oxide nanoparticles

A number of studies have investigated the adverse toxic effects of titanium dioxide (TiO₂) nanoparticles (NPs) or zinc oxide (ZnO) NPs. Information on the potential genotoxic effects of the interactions of TiO₂ NPs and ZnO NPs in vivo is lacking. Therefore, this study was designed to investigate the cytogenotoxicity of TiO₂ NPs or ZnO NPs alone or their mixtures using the bone marrow micronucleus assay, and mechanism of damage through the evaluation of oxidative stress parameters in the liver and kidney tissues of Swiss mice. Intraperitoneal administration of doses between 9.38 and 150.00 mg/kg of TiO₂ NPs or ZnO NPs or TiO₂ NPs + ZnO NPs was performed for 5 and 10 days, respectively. TiO₂ NPs alone induced a significant (P < 0.05) increase in micronucleated (Mn) polychromatic erythrocytes (PCEs) at the applied doses compared with the negative controls, with a significant difference between 5 and 10 days for TiO₂ NPs alone and TiO₂ NPs + ZnO NPs. Concurrently, TiO₂ NPs alone for 5 days and TiO₂ NPs and TiO₂ NPs + ZnO NPs for 10 days significantly (P < 0.05) decreased the percentage PCE: normochromatic erythrocyte (NCE) indicating cytotoxicity; with a significant difference between the two periods. Significant (P < 0.001) changes in the activities of superoxide dismutase (SOD) and catalase (CAT), and levels of reduced glutathione (GSH) and malondialdehyde (MDA) were observed in the liver and kidney of mice exposed to TiO₂ NPs or ZnO NPs alone or their mixtures. These results suggest that TiO₂ NPs alone was genotoxic; TiO₂ NPs and TiO₂ NPs + ZnO NPs were noticeably cytotoxic while ZnO NPs was not cytogenotoxic. The individual NPs or their mixtures induced oxidative stress.     

Pharyngeal aspiration of metal oxide nanoparticles showed potential of allergy aggravation effect to inhaled ovalbumin

Abstract

The inhalation of manufactured metal oxide nanoparticles may lead to pulmonary toxicity. For instance, ZnO nanoparticles are known to induce pulmonary oxidative stress and inflammation. On the other hand, the pulmonary toxicity of TiO₂ nanoparticles is less than that of ZnO nanoparticles. Although, there have been some investigations concerning the induction of pulmonary oxidative stress and inflammation caused by manufactured metal oxide nanoparticles. And, although, it has reported that some nanoparticles cause aggravation of allergic reactions, there have so far been no reports regarding allergy aggravation effects of manufactured metal oxide nanoparticles. In this study, three types of nanoparticles, TiO₂, ZnO and SiO₂, were administered to mouse lungs by pharyngeal aspiration. Subsequently, the mice inhaled ovalbumin (OVA) a total of eight times over 3 weeks. After inhalation of OVA, the concentrations of total IgE, OVA-specific IgE and OVA-specific IgG₁ in serum increased in the mice treated with ZnO. TiO₂ and SiO₂ nanoparticles did not affect the OVA-specific IgE and IgG₁ levels. These results suggest that ZnO nanoparticles have the potential to aggravate allergic reactions. The results also suggest that Zn²⁺ release from ZnO nanoparticles is involved in the aggravation potential of allergies. However, pharyngeal aspiration of ZnCl₂ solution was not able to aggravate allergic reactions. Continuous Zn²⁺ release from ZnO nanoparticles to the lung is necessary for the aggravation of allergic reactions.     

Effects of acute systemic administration of TiO2, ZnO,SiO2, and Ag nanoparticles on hemodynamics,hemostasis and leukocyte recruitment

Abstract

It has been suggested that engineered nanomaterials (ENM), once arrived in the circulation, may affect the cardiovascular system. The aim of this in vivo study was to screen major cardiovascular effects of acute systemic administration of a panel of five nanomaterials, TiO₂ anatase (NM-101), TiO₂ rutile (NM-104), ZnO (NM-110), SiO₂ (NM-200) and Ag (NM-300). Mice were anesthetized and the ENM were injected at a dose of 1?mg/kg via a catheter placed in the left femoral artery. Hemodynamic parameters were determined by invasive measurement of blood pressure and non-invasive measurement of heart rate. Ten minutes after injection of the ENM, the formation of light/dye-induced thrombi was assessed in the cremasteric microcirculation by intravital microscopy. In addition, the numbers of rolling, firmly adherent and transmigrated leukocytes were recorded in postcapillary cremasteric venules over a time period of 120?min after injection of ENM by intravital microscopy. The systemic administration of a single dose of the ENM tested did not dramatically alter hemodynamic parameters or affect early steps of leukocyte recruitment. However, the presence of circulating TiO₂ anatase, but not of TiO₂ rutile, SiO₂, ZnO or Ag nanoparticles, significantly accelerated thrombus formation in the murine microcirculation. Moreover, TiO₂ anatase but not TiO₂ rutile nanoparticles increased murine platelet aggregation in vitro. Taken together, only one of the five systemically administered ENM, TiO₂ anatase, affected hemostasis, whereas none of the ENM tested in this screening study dramatically modulated hemodynamic parameters or early steps of leukocyte recruitment.     

Effects of subtoxic concentrations of TiO(2) and ZnO nanoparticles on human lymphocytes, dendritic cells and exosome production

Metal oxide nanoparticles are widely used in the paint and coating industry as well as in cosmetics, but the knowledge of their possible interactions with the immune system is very limited. Our aims were to investigate if commercially available TiO₂ and ZnO nanoparticles may affect different human immune cells and their production of exosomes, nano-sized vesicles that have a role in cell to cell communication. We found that the TiO₂ or ZnO nanoparticles at concentrations from 1 to 100 μg/mL did not affect the viability of primary human peripheral blood mononuclear cells (PBMC). In contrast, monocyte-derived dendritic cells (MDDC) reacted with a dose dependent increase in cell death and caspase activity to ZnO but not to TiO₂ nanoparticles. Non-toxic exposure, 10 μg/mL, to TiO₂ and ZnO nanoparticles did not significantly alter the phenotype of MDDC. Interestingly, ZnO but not TiO₂ nanoparticles induced a down regulation of FcγRIII (CD16) expression on NK-cells in the PBMC population, suggesting that subtoxic concentrations of ZnO nanoparticles might have an effect on FcγR-mediated immune responses. The phenotype and size of exosomes produced by PBMC or MDDC exposed to the nanoparticles were similar to that of exosomes harvested from control cultures. TiO₂ or ZnO nanoparticles could not be detected within or associated to exosomes as analyzed with TEM. We conclude that TiO₂ and ZnO nanoparticles differently affect immune cells and that evaluations of nanoparticles should be performed even at subtoxic concentrations on different primary human immune cells when investigating potential effects on immune functions.     

Multilaboratory evaluation of 15 bioassays for (eco)toxicity screening and hazard ranking of engineered nanomaterials: FP7 project NANOVALID

Within EU FP7 project NANOVALID, the (eco)toxicity of 7 well-characterized engineered nanomaterials (NMs) was evaluated by 15 bioassays in 4 laboratories. The highest tested nominal concentration of NMs was 100?mg/l. The panel of the bioassays yielded the following toxicity order: Ag?>?ZnO?>?CuO?>?TiO_2?>_?MWCNTs?>?SiO_2?>_?Au. Ag, ZnO and CuO proved very toxic in the majority of assays, assumingly due to dissolution. The latter was supported by the parallel analysis of the toxicity of respective soluble metal salts. The most sensitive tests/species were Daphnia magna (towards Ag NMs, 24-h EC_50?=_?0.003?mg Ag/l), algae Raphidocelis subcapitata (ZnO and CuO, 72-h EC_50?=_?0.14?mg Zn/l and 0.7?mg Cu/l, respectively) and murine fibroblasts BALB/3T3 (CuO, 48-h EC_50?=_?0.7?mg Cu/l). MWCNTs showed toxicity only towards rat alveolar macrophages (EC_50?=_?15.3?mg/l) assumingly due to high aspect ratio and TiO₂ towards R. subcapitata (EC_50?=_?6.8?mg Ti/l) due to agglomeration of TiO₂ and entrapment of algal cells. Finally, we constructed a decision tree to select the bioassays for hazard ranking of NMs. For NM testing, we recommend a multitrophic suite of 4 in vitro (eco)toxicity assays: 48-h D. magna immobilization (OECD202), 72-h R. subcapitata growth inhibition (OECD201), 30-min Vibrio fischeri bioluminescence inhibition (ISO2010) and 48-h murine fibroblast BALB/3T3 neutral red uptake in vitro (OECD129) representing crustaceans, algae, bacteria and mammalian cells, respectively. Notably, our results showed that these assays, standardized for toxicity evaluation of “regular” chemicals, proved efficient also for shortlisting of hazardous NMs. Additional assays are recommended for immunotoxicity evaluation of high aspect ratio NMs (such as MWCNTs).     

The effects of endoplasmic reticulum stress inducer thapsigargin on the toxicity of ZnO or TiO2 nanoparticles to human endothelial cells

It was recently shown that ZnO nanoparticles (NPs) could induce endoplasmic reticulum (ER) stress in human umbilical vein endothelial cells (HUVECs). If ER stress is associated the toxicity of ZnO NPs, the presence of ER stress inducer thapsigargin (TG) should alter the response of HUVECs to ZnO NP exposure. In this study, we addressed this issue by assessing cytotoxicity, oxidative stress and inflammatory responses in ZnO NP exposed HUVECs with or without the presence of TG. Moreover, TiO₂ NPs were used to compare the effects. Exposure to 32?μg/mL ZnO NPs (p?2 NPs (p?>?0.05), significantly induced cytotoxicity as assessed by WST-1 and neutral red uptake assay, as well as intracellular ROS. ZnO NPs dose-dependently increased the accumulation of intracellular Zn ions, and ZnSO₄ induced similar cytotoxic effects as ZnO NPs, which indicated a role of Zn ions. The release of inflammatory proteins tumor necrosis factor α (TNFα) and interleukin-6 (IL-6) or the adhesion of THP-1 monocytes to HUVECs was not significantly affected by ZnO or TiO₂ NP exposure (p?>?0.05). The presence of 250?nM TG significantly induced cytotoxicity, release of IL-6 and THP-1 monocyte adhesion (p?p?>?0.05). ANOVA analysis indicated no interaction between exposure to ZnO NPs and the presence of TG on almost all the endpoints (p?>?0.05) except neutral red uptake assay (p?相似文献   

Metabolomics reveals the perturbations in the metabolome of Caenorhabditis elegans exposed to titanium dioxide nanoparticles

Abstract

The increasing use of nanotechnology in our daily life can have many unintended effects and pose adverse impact on human health, environment and ecosystems. Wider application of engineered nanoparticles, especially TiO₂ nanoparticles (TiO₂ NP) necessitates the understanding of toxicity and mechanism of action. Metabolomics provides a unique opportunity to find out biomarkers of nanoparticles exposure, which leads to the identification of cellular pathways and their biological mechanisms. Gas chromatography mass spectrometry (GC–MS)-based metabolomics approach was used in the present study to understand the toxicity of sub-lethal concentrations (7.7 and 38.5?µg/ml) of TiO₂ NP (<25?nm) in well-known, soil nematode Caenorhabditis elegans (C. elegans). Multivariate pattern recognition analysis reflected the perturbations in the metabolism (amino acids, organic acids, sugars) of C. elegans on exposure to TiO₂ NP. The biological pathways affected due to the exposure of TiO₂ NP were identified, among them mainly affected pathways are tricarboxylic acid (TCA) cycle, arachidonic acid metabolism and glyoxalate dicarobxylate metabolism. The manifestation of differential metabolic profile in organism exposed to TiO₂ (NP or bulk particle) was witnessed as an effect on reproduction. The present study demonstrates that metabolomics can be employed as a tool to understand the potential toxicity of nanoparticles in terms of organism–environment interactions as well as in assessing the organism function at the molecular level.     

Comparative effects of TiO2 and ZnO nanoparticles on growth and ultrastructure of ovarian antral follicles

Titanium dioxide (TiO₂) and zinc oxide (ZnO) nanoparticles (NP) have been demonstrated to reach the ovary. However, the potential detrimental effects of these metal-based NP on ovarian antral follicles and whether they can be directly taken up by follicular cells are unknown. The aim of this study was to evaluate whether TiO₂ and ZnO NP internalize into the antral follicle, and further compared any potential detrimental effects of either NP on growth, ultrastructure and viability of antral follicles. It has been described that TiO₂ and ZnO NP induce oxidative stress, thus this study indirectly assessed whether oxidative stress was involved. Antral follicles were cultured with TiO₂ (5, 25 and 50 μg/mL) or ZnO (5, 15 and 25 μg/mL) NP for 96 h. TiO₂ NP were internalized and agglomerated into cells, increased follicle diameter and disrupted the cytoskeleton arrangement, effects that were partially prevented by a co-exposure with trolox. Moreover, ZnO NP partially dissolved into culture media, decreased follicle diameter, and disrupted cytoskeletal arrangement, and these effects were not prevented by trolox. Ultrastructural alterations induced by exposure to both NP were evidenced by impaired transzonal projections and swelling mitochondria. Oxidative stress mediates TiO₂ NP-induced effects but not those from ZnO NP in antral follicle development. Our results suggest that both NP induced ovarian follicle toxicity through different toxic mechanisms, possibly due to a stimulation of ZnO NP solubility and agglomeration of TiO₂ NP into the follicular cells.     

Influence of bovine serum albumin pre-incubation on toxicity and ER stress-apoptosis gene expression in THP-1 macrophages exposed to ZnO nanoparticles

When entering a biological environment, proteins could be adsorbed onto nanoparticles (NPs), which can potentially influence the toxicity of NPs. This study used bovine serum albumin (BSA) as the model for serum protein and investigated its interactions with three different types of ZnO NPs, coded as XFI06 (pristine NPs of 20?nm), NM110 (pristine NPs of 100?nm) and NM111 (hydrophobic NPs of 130?nm). Atomic force microscope indicated the adsorption of BSA to ZnO NPs, leading to the increase of NP diameters. Pre-incubation with BSA did not significantly affect hydrodynamic size but decreased Zeta potential of NM110 and NM111. The fluorescence and synchronous fluorescence of BSA were quenched after pre-incubation with ZnO NPs, and the quenching effects were more obvious for XFI06 and NM110. Exposure to all types of ZnO NPs significantly induced cytotoxicity and lysosomal destabilization, which was slightly alleviated when NPs were pre-incubated with BSA. However, ZnO NPs with or without pre-incubation of BSA resulted in comparable intracellular Zn ions, glutathione and reactive oxygen species in THP-1 macrophages. Exposure to ZnO NPs promoted the expression of endoplasmic reticulum (ER) stress markers (DDIT3 and XBP-1s) and apoptosis genes (CASP9 and CASP12). Pre-incubation with BSA had minimal impact on ER stress gene expression but decreased apoptosis gene expression. Combined, these results suggested that pre-incubation with BSA could modestly alleviate the cytotoxicity and reduce ER stress related apoptosis gene expression in THP-1 macrophages after ZnO NP exposure.     

Industrial worker exposure to airborne particles during the packing of pigment and nanoscale titanium dioxide

Context: Titanium dioxide (TiO2) factory workers’ source specific exposure and dose to airborne particles was studied extensively for particles between 5?nm and 10 μm in size.

Objective: We defined TiO₂ industry workers’ quantitative inhalation exposure levels during the packing of pigment TiO₂ (pTiO₂) and nanoscale TiO₂ (nTiO₂) material from concentrations measured at work area.

Methods: Particle emissions from different work events were identified by linking work activity with the measured number size distributions and mass concentrations of particles. A lung deposit model was used to calculate regional inhalation dose rates in units of particles min^?1 and μg min^?1 without use of respirators.

Results: Workers’ average exposure varied from 225 to 700 μg m^?3 and from 1.15?×?10⁴ to 20.1?×?10⁴ cm^?4. Over 90% of the particles were smaller than 100?nm. These were mainly soot and particles formed from process chemicals. Mass concentration originated primarily from the packing of pTiO₂ and nTiO₂ agglomerates. The nTiO₂ exposure resulted in a calculated dose rate of 3.6?×?10⁶ min^?1 and 32 μg min^?1 where 70% of the particles and 85% of the mass was deposited in head airways.

Conclusions: The recommended TiO₂ exposure limits in mass by NIOSH and in particle number by IFA were not exceeded. We recommend source-specific exposure assessment in order to evaluate the workers’ risks. In nTiO₂ packing, mass concentration best describes the workers’ exposure to nTiO₂ agglomerates. Minute dose rates enable the simulation of workers’ risks in different exposure scenarios.