Organ burden and pulmonary toxicity of nano-sized copper (II) oxide particles after short-term inhalation exposure

Nanoparticle exposure and hazard in the ceramic industry: an overview of potential sources, toxicity and health effects

The ceramic industry is an industrial sector of great impact in the global economy that has been benefiting from advances in materials and processing technologies. Ceramic manufacturing has a strong potential for airborne particle formation and emission, namely of ultrafine particles (UFP) and nanoparticles (NP), meaning that workers of those industries are at risk of potential exposure to these particles. At present, little is known on the impact of engineered nanoparticles (ENP) on the environment and human health and no established Occupational Exposure Limits (OEL) or specific regulations to airborne nanoparticles (ANP) exposure exist raising concerns about the possible consequences of such exposure. In this paper, we provide an overview of the current knowledge on occupational exposure to NP in the ceramic industry and their impact on human health. Possible sources and exposure scenarios, a summary of the existing methods for evaluation and monitoring of ANP in the workplace environment and proposed Nano Reference Values (NRV) for different classes of NP are presented. Case studies on occupational exposure to ANP generated at different stages of the ceramic manufacturing process are described. Finally, the toxicological potential of intentional and unintentional ANP that have been identified in the ceramic industry workplace environment is discussed based on the existing evidence from in vitro and in vivo inhalation toxicity studies.

Livestock farm particulate matter enhances airway inflammation in mice with or without allergic airway disease

Effects of airborne biological particulate matter (BioPM; from livestock farms) on the pulmonary airways are not well studied. The aim of the present study was to investigate whether fine (<2.5 μm) BioPM derived from indoor animal stables (two chicken and two pig farms) could modify airway allergic responses by using a mouse model of allergic airway disease (allergic asthma). After intraperitoneal ovalbumin (OVA) sensitization mice were either intranasally challenged with OVA (allergic mice) or saline (non-allergic controls). Mice were also intranasally treated with farm-derived BioPM. Bronchoalveolar lavage fluid (BALF), blood and lung tissues were collected one day after intranasal exposure. BioPM from all the farms caused an acute neutrophilic inflammatory response in non-allergic mice. In allergic mice, BioPM derived from pig farm 2 induced a larger cellular inflammatory response than other farm-derived BioPM. All farm BioPM elicited Th17 cytokine (Interleukin (IL)-23) production except chicken farm 2, whereas Th2 cytokine (IL-5) increase was only induced by BioPM collected from chicken farm 2. These results indicate the exposure of BioPM from chicken and pig farms may cause the enhancement of airway allergic response in mice following exposure to OVA. More variation in the responses between farms was observed in allergic than non-allergic mice. Understanding the source and doses of BioPM that may affect the airway allergic response could help susceptible individuals to avoid worsening their respiratory diseases.

Up-regulation of miR-297 mediates aluminum oxide nanoparticle-induced lung inflammation through activation of Notch pathway

Exposure to Aluminum oxide nanoparticles (Al₂O₃ NPs) has been associated with pulmonary inflammation in recent years; however, the underlying mechanism that causes adverse effects remains unclear. In the present study, we characterized microRNA (miRNA) expression profiling in human bronchial epithelial (HBE) cells exposed to Al₂O₃ NPs by miRNA microarray. Among the differentially expressed miRNAs, miR-297, a homologous miRNA in Homo sapiens and Mus musculus, was significantly up-regulated following exposure to Al₂O₃ NPs, compared with that in control. On combined bioinformatic analysis, proteomics analysis, and mRNA microarray, NF-κB-activating protein (NKAP) was found to be a target gene of miR-297 and it was significantly down-regulated in Al₂O₃ NPs-exposed HBE cells and murine lungs, compared with that in control. Meanwhile, inflammatory cytokines, including IL-1β and TNF-α, were significantly increased in bronchoalveolar lavage fluid (BALF) from mice exposed to Al₂O₃ NPs. Then we set up a mouse model with intranasal instillation of antagomiR-297 to further confirm that inhibition of miR-297 expression can rescue pulmonary inflammation via Notch pathway suppression. Collectively, our findings suggested that up-regulation of miR-297 expression was an upstream driver of Notch pathway activation, which might be the underlying mechanism involved in lung inflammation induced by exposure to Al₂O₃ NPs.

Iron-Doping of Copper Oxide Nanoparticles Lowers Their Toxic Potential on C6 Glioma Cells

Copper oxide nanoparticles (CuO-NPs) are well known for their cytotoxicity which in part has been attributed to the release of copper ions from CuO-NPs. As iron-doping has been reported to reduce the susceptibility of CuO-NPs to dissolution, we have compared pure CuO-NPs and CuO-NPs that had been doped with 10% iron (CuO-Fe-NPs) for copper release and for their toxic potential on C6 glioma cells. Physicochemical characterization revealed that dimercaptosuccinate (DMSA)-coated CuO-NPs and CuO-Fe-NPs did not differ in their size or zeta potential. However, the redox activity and liberation of copper ions from CuO-Fe-NPs was substantially slower compared to that from CuO-NPs, as demonstrated by cyclic voltammetry and by the photometric quantification of the copper ion-bathocuproine complex, respectively. Exposure of C6 cells to these NPs caused an almost identical cellular copper accumulation and each of the two types of NPs induced ROS production and cell toxicity. However, the time- and concentration-dependent loss in cell viability was more severe for cells that had been treated with CuO-NPs compared to cells exposed to CuO-Fe-NPs. Copper accumulation and toxicity after exposure to either CuO-NPs or CuO-Fe-NPs was prevented in the presence of copper chelators, while neutralization of the lysosomal pH by bafilomycin A1 prevented toxicity without affecting cellular copper accumulation or ROS production. These data demonstrate that iron-doping does not affect cellular accumulation of CuO-NPs and suggests that the intracellular liberation of copper ions from CuO-NPs is slowed by the iron doping, which in turn lowers the cell toxic potential of iron-doped CuO-NPs.

Toxicity assessment of metal oxide nanomaterials using in vitro screening and murine acute inhalation studies

Characterizations and in vitro toxicity screening were performed on metal oxide engineered nanomaterials (ENMs) independently comprising ZnO, CuO, CeO₂, Fe₂O₃, WO₃, V₂O₅, TiO₂, Al₂O₃ and MgO. Nanomaterials that exhibited the highest toxicity responses in the in vitro screening assays (ZnO, CuO, and V₂O₅) and the lesser explored material WO₃ were tested for acute pulmonary toxicity in vivo. Female and male mice (C57Bl/6J) were exposed to aerosolized metal oxide ENMs in a nose-only exposure system and toxicity outcomes (biomarkers of cytotoxicity, immunotoxicity, inflammation, and lung histopathology) at 4 and 24 h after the start of exposure were assessed. The studies were performed as part of the NIEHS Nanomaterials Health Implications Research consortium with the purpose of investigating the effects of ENMs on various biological systems. ENMs were supplied by the Engineered Nanomaterials Resource and Coordination Core. Among the ENMs studied, the highest toxicity was observed for CuO and ZnO NPs in both in vitro and in vivo acute models. Compared to sham-exposed controls, there was a significant increase in bronchoalveolar lavage neutrophils and proinflammatory cytokines and a loss of macrophage viability at both 4 h and 24 h for ZnO and CuO but not seen for V₂O₅ or WO₃. These effects were observed in both female and male mice. The cell viability performed after in vitro exposure to ENMs and assessment of lung inflammation after acute inhalation exposure in vivo were shown to be sensitive endpoints to predict ENM acute toxicity.

Understanding Dissolution Rates via Continuous Flow Systems with Physiologically Relevant Metal Ion Saturation in Lysosome

Dissolution rates of nanomaterials can be decisive for acute in vivo toxicity (via the released ions) and for biopersistence (of the remaining particles). Continuous flow systems (CFSs) can screen for both aspects, but operational parameters need to be adjusted to the specific physiological compartment, including local metal ion saturation. CFSs have two adjustable parameters: the volume flow-rate and the initial particle loading. Here we explore the pulmonary lysosomal dissolution of nanomaterials containing the metals Al, Ba, Zn, Cu over a wide range of volume flow-rates in a single experiment. We identify the ratio of particle surface area (SA) per volume flow-rate (SA/V) as critical parameter that superimposes all dissolution rates of the same material. Three complementary benchmark materials—ZnO (quick dissolution), TiO₂ (very slow dissolution), and BaSO₄ (partial dissolution)—consistently identify the SA/V range of 0.01 to 0.03 h/cm as predictive for lysosomal pulmonary biodissolution. We then apply the identified method to compare against non-nanoforms of the same substances and test aluminosilicates. For BaSO₄ and TiO₂, we find high similarity of the dissolution rates of their respective nanoform and non-nanoform, governed by the local ion solubility limit at relevant SA/V ranges. For aluminosilicates, we find high similarity of the dissolution rates of two Kaolin nanoforms but significant dissimilarity against Bentonite despite the similar composition.

Metal-Based Nanoparticles as Antimicrobial Agents: An Overview

Metal-based nanoparticles have been extensively investigated for a set of biomedical applications. According to the World Health Organization, in addition to their reduced size and selectivity for bacteria, metal-based nanoparticles have also proved to be effective against pathogens listed as a priority. Metal-based nanoparticles are known to have non-specific bacterial toxicity mechanisms (they do not bind to a specific receptor in the bacterial cell) which not only makes the development of resistance by bacteria difficult, but also broadens the spectrum of antibacterial activity. As a result, a large majority of metal-based nanoparticles efficacy studies performed so far have shown promising results in both Gram-positive and Gram-negative bacteria. The aim of this review has been a comprehensive discussion of the state of the art on the use of the most relevant types of metal nanoparticles employed as antimicrobial agents. A special emphasis to silver nanoparticles is given, while others (e.g., gold, zinc oxide, copper, and copper oxide nanoparticles) commonly used in antibiotherapy are also reviewed. The novelty of this review relies on the comparative discussion of the different types of metal nanoparticles, their production methods, physicochemical characterization, and pharmacokinetics together with the toxicological risk encountered with the use of different types of nanoparticles as antimicrobial agents. Their added-value in the development of alternative, more effective antibiotics against multi-resistant Gram-negative bacteria has been highlighted.

Toward Rigorous Materials Production: New Approach Methodologies Have Extensive Potential to Improve Current Safety Assessment Practices

Advanced material development, including at the nanoscale, comprises costly and complex challenges coupled to ensuring human and environmental safety. Governmental agencies regulating safety have announced interest toward acceptance of safety data generated under the collective term New Approach Methodologies (NAMs), as such technologies/approaches offer marked potential to progress the integration of safety testing measures during innovation from idea to product launch of nanomaterials. Divided in overall eight main categories, searchable databases for grouping and read across purposes, exposure assessment and modeling, in silico modeling of physicochemical structure and hazard data, in vitro high-throughput and high-content screening assays, dose-response assessments and modeling, analyses of biological processes and toxicity pathways, kinetics and dose extrapolation, consideration of relevant exposure levels and biomarker endpoints typify such useful NAMs. Their application generally agrees with articulated stakeholder needs for improvement of safety testing procedures. They further fit for inclusion and add value in nanomaterials risk assessment tools. Overall 37 of 50 evaluated NAMs and tiered workflows applying NAMs are recommended for considering safer-by-design innovation, including guidance to the selection of specific NAMs in the eight categories. An innovation funnel enriched with safety methods is ultimately proposed under the central aim of promoting rigorous nanomaterials innovation.

Copper-Heparin Inhalation Therapy To Repair Emphysema: A Scientific Rationale

Current pharmacotherapy of chronic obstructive pulmonary disease (COPD) aims at reducing respiratory symptoms and exacerbation frequency. Effective therapies to reduce disease progression, however, are still lacking. Furthermore, COPD medications showed less favorable effects in emphysema than in other COPD phenotypes. Elastin fibers are reduced and disrupted, whereas collagen levels are increased in emphysematous lungs. Protease/antiprotease imbalance has historically been regarded as the sole cause of emphysema. However, it is nowadays appreciated that emphysema may also be provoked by perturbations in the sequential repair steps following elastolysis. Essentiality of fibulin-5 and lysyl oxidase-like 1 in the elastin restoration process is discussed, and it is argued that copper deficiency is a plausible reason for failing elastin repair in emphysema patients. Since copper-dependent lysyl oxidases crosslink elastin as well as collagen fibers, copper supplementation stimulates accumulation of both proteins in the extracellular matrix. Restoration of abnormal elastin fibers in emphysematous lungs is favorable, whereas stimulating pulmonary fibrosis formation by further increasing collagen concentrations and organization is detrimental. Heparin inhibits collagen crosslinking while stimulating elastin repair and might therefore be the ideal companion of copper for emphysema patients. Efficacy and safety considerations may lead to a preference of pulmonary administration of copper-heparin over systemic administration.

The nanoGRAVUR framework to group (nano)materials for their occupational, consumer, environmental risks based on a harmonized set of material properties, applied to 34 case studies

The project nanoGRAVUR (BMBF, 2015-2018) developed a framework for grouping of nanomaterials. Different groups may result for each of the three distinct perspectives of occupational, consumer and environmental safety. The properties, methods and descriptors are harmonised between the three perspectives and are based on: Tier 1 intrinsic physico-chemical properties (what they are) or GHS classification of the non-nano-form (human tox, ecotox, physical hazards); Tier 2 extrinsic physico-chemical properties, release from nano-enabled products, in vitro assays with cells (where they go; what they do); Tier 3 case-specific tests, potentially in vivo studies to substantiate the similarity within groups or application-specific exposure testing. Amongst all properties, dissolution and transformation are least modulated by different nanoforms within one substance, whereas dustiness, dispersion stability, abiotic and especially in vitro surface reactivity vary more often between different nanoforms. The methods developed or selected by nanoGRAVUR fill several gaps highlighted in the ProSafe reviews, and are useful to implement (i) the concept of nanoforms of the European Chemicals Agency (ECHA) and (ii) the concept of discrete forms of the United States Environmental Protection Agency (EPA). One cannot assess the significance of a dissimilarity, if the dynamic range of that property is unknown. Benchmark materials span dynamic ranges that enable us to establish bands, often with order-of-magnitude ranges. In 34 case studies we observed high biological similarity within each substance when we compared different (nano)forms of SiO2, BaSO4, kaolin, CeO2, ZnO, organic pigments, especially when we compared forms that are all untreated on the surface. In contrast, different Fe2O3 or TiO2 (nano)forms differ more significantly. The same nanoforms were also integrated in nano-enabled products (NEPs) for automotive coatings, clinker-reduced cements, cosmetic sunscreen, and lightweight polymers.

Determination of number-based size distribution of silica particles using centrifugal field-flow fractionation

Determination of the number-based size distribution of silica particles using the centrifugal field-flow fractionation (CF3) method was investigated. Since the accurate determination of the number-based size distribution of materials is essential in the fields of nanotechnology and biotechnology, the establishment of a robust evaluation method is attractive. We explored optimization of the fractionation conditions for CF3 using silica particles. Using pure water media as the eluent, a band broadening effect was clearly found, and this effect became stronger with higher initial centrifugal field strengths. After addition of 0.05 wt% aqueous FL-70 as a dispersant in the eluent, size fractionation could be performed effectively at higher centrifugal field strengths, providing excellent size separation results. After optimization of the CF3 separation condition, we determined the number-based size distribution of silica particles using three methods: FE-SEM only, CF3 with multi-angle light scattering (CF3-MALS), and a combined CF3 with FE-SEM method (CF3-FE-SEM). To meaningfully compare the CF3-MALS results with the other two methods, we transformed the light scattering intensity to particle numbers using Mie theory. The determined number-based mean sizes of silica particles by the three methods agreed well; however, the evaluated standard deviation of the number-based size distribution of silica particles by the CF3-MALS method was slightly different. This was attributed to the unreliable sizing by MALS of smaller sized particles or low particle concentrations. The combined CF3-FE-SEM method provided near equal accuracy as the costly FE-SEM only and allowed for a significantly faster methodology because CF3 separation reduced the number of silica particles required for an accurate sizing down to just 50 particles per fraction.

Surface PEGylation suppresses pulmonary effects of CuO in allergen-induced lung inflammation

BACKGROUND

Copper oxide (CuO) nanomaterials are used in a wide range of industrial and commercial applications. These materials can be hazardous, especially if they are inhaled. As a result, the pulmonary effects of CuO nanomaterials have been studied in healthy subjects but limited knowledge exists today about their effects on lungs with allergic airway inflammation (AAI). The objective of this study was to investigate how pristine CuO modulates allergic lung inflammation and whether surface modifications can influence its reactivity. CuO and its carboxylated (CuO COOH), methylaminated (CuO NH₃) and PEGylated (CuO PEG) derivatives were administered here on four consecutive days via oropharyngeal aspiration in a mouse model of AAI. Standard genome-wide gene expression profiling as well as conventional histopathological and immunological methods were used to investigate the modulatory effects of the nanomaterials on both healthy and compromised immune system.

RESULTS

Our data demonstrates that although CuO materials did not considerably influence hallmarks of allergic airway inflammation, the materials exacerbated the existing lung inflammation by eliciting dramatic pulmonary neutrophilia. Transcriptomic analysis showed that CuO, CuO COOH and CuO NH₃ commonly enriched neutrophil-related biological processes, especially in healthy mice. In sharp contrast, CuO PEG had a significantly lower potential in triggering changes in lungs of healthy and allergic mice revealing that surface PEGylation suppresses the effects triggered by the pristine material.

CONCLUSIONS

CuO as well as its functionalized forms worsen allergic airway inflammation by causing neutrophilia in the lungs, however, our results also show that surface PEGylation can be a promising approach for inhibiting the effects of pristine CuO. Our study provides information for health and safety assessment of modified CuO materials, and it can be useful in the development of nanomedical applications.

Using 3D gastrointestinal tract in vitro models with microfold cells and mucus secreting ability to assess the hazard of copper oxide nanomaterials

BACKGROUND

Copper oxide nanomaterials (CuO NMs) are exploited in many products including inks, cosmetics, textiles, wood preservatives and food contact materials. Their incorporation into these products may enhance oral exposure in consumer, environmental and occupational settings. Undifferentiated and differentiated monocultures of Caco-2 cells are commonly used to assess NM toxicity to the intestine in vitro. However, the integration of other cell types into Caco-2 in vitro models increases their physiological relevance. Therefore, the aim of this study is to evaluate the toxicity of CuO NMs and copper sulphate (CuSO4) to intestinal microfold (M) cell (Caco-2/Raji B) and mucus secreting (Caco-2/HT29-MTX) co-culture in vitro models via assessment of their impact on barrier integrity, viability and interleukin (IL)-8 secretion. The translocation of CuO NMs and CuSO4 across the intestinal barrier was also investigated in vitro.

RESULTS

CuO NMs and CuSO4 impaired the function of the intestinal barrier in the co-culture models [as indicated by a reduction in transepithelial electrical resistance (TEER) and Zonular occludens (ZO-1) staining intensity]. Cu translocation was observed in both models but was greatest in the Caco-2/Raji B co-culture. CuO NMs and CuSO4 stimulated an increase in IL-8 secretion, which was greatest in the Caco-2/HT29-MTX co-culture model. CuO NMs and CuSO4 did not stimulate a loss of cell viability, when assessed using light microscopy, nuclei counts and scanning electron microscopy. CuO NMs demonstrated a relatively similar level of toxicity to CuO4 in both Caco-2/Raji B and Caco-2/HT29-MTX co- culture models.

CONCLUSIONS

The Caco-2/Raji B co-culture model was more sensitive to CuO NM and CuSO4 toxicity than the Caco-2/HT29-MTX co-culture model. However, both co-culture models were less sensitive to CuO NM and CuSO4 toxicity than simple monocultures of undifferentiated and differentiated Caco-2 cells, which are more routinely used to investigate NM toxicity to the intestine. Obtained data can therefore feed into the design of future studies which assess the toxicity of substances (e.g. NMs) and pathogens to the intestine (e.g. by informing model and endpoint selection). However, more testing with a wider panel of NMs would be beneficial in order to help select which in vitro models and endpoints to prioritise when screening the safety of ingested NMs. Comparisons with in vivo findings will also be essential to identify the most suitable in vitro model to screen the safety of ingested NMs.

Inhalation toxicity profiles of particulate matter: a comparison between brake wear with other sources of emission

Objective: There is substantial evidence that exposure to airborne particulate matter (PM) from road traffic is associated with adverse health outcomes. Although it is often assumed to be caused by vehicle exhaust emissions such as soot, other components may also contribute to detrimental effects. The toxicity of fine PM (PM2.5; <2.5 µm mass median aerodynamic diameter) released from brake pads was compared to PM from other sources. Materials and methods: PM2.5 of different types of brake pads (low-metallic, semi-metallic, NAO and ECE-NAO hybrid), tires and road pavement, poultry as well as the combustion of diesel fuel and wood (modern and old-fashioned stove technologies) were collected as suspensions in water. These were subsequently aerosolized for inhalation exposures. Female BALB/cOlaHsd mice were exposed for 1.5, 3, or 6 hours by nose-only inhalation up to 9 mg/m³. Results: Neither cytotoxicity nor oxidative stress was observed after exposure to any of the re-aerosolized PM2.5 samples. Though, at similar PM mass concentrations the potency to induce inflammatory responses was strongly dependent on the emission source. Exposure to most examined PM2.5 sources provoked inflammation including those derived from the poultry farm, wear emissions of the NAO and ECE-NAO hybrid brake pads as well as diesel and wood combustion, as indicated by neutrophil chemoattractant, KC and MIP-2 and lung neutrophil influx. Discussion and conclusions: Our study revealed considerable variability in the toxic potency of brake wear particles. Understanding of sources that are most harmful to health can provide valuable information for risk management strategies and could help decision-makers to develop more targeted air pollution regulation.

CuO nanoparticle penetration through intact and damaged human skin

Trans-dermal in vitro study of CuO nanoparticles in contact with intact and damaged human skin using a Franz cell model.

Original Research Article (Experimental): Targeting fungal menace through copper nanoparticles and Tamrajal

Background

WHO reports, an escalation of antibiotic resistance in opportunistic pathogens like Candida. Tamrajal, i.e., water stored in copper vessels has been proclaimed as health elixir by ancient Ayurveda. Vis-a-Vis the use of copper contact surfaces and nanoparticles has gained significance for their antimicrobial effects. It thus seems imperative to examine copper nanoparticles and tamrajal as promising alternatives to existing antifungals.

Objective

This study not only assessed the influence of Tamrajal and copper nanoparticles on the morphological alterations of the Candida and its biofilm forming ability, but also on their ability to destroy preformed biofilms.

Materials and methods

Copper oxide nanoparticles as well as Tamrajal were evaluated as complementary as well as stand-alone antimicrobial agents. ‘Time kill assay’ and ‘germ tube inhibition test’ were performed as end-point analysis for pathogenesis, while biofilm quantification, performed to assess the colonizing capability of Candida. Scanning Electron Microscope was used for visualizing the cells, whilst ICP-AES to determine the copper concentration.

Results

92–100% cytotoxicity to the fluconazole resistant Candida species was observed with copper oxide nanoparticles as well as tamrajal during 24hr time kill assay. The study also confirmed complete germ tube inhibition by copper in both its forms in addition to the reduction in the biofilm production.

Conclusion

Compared to the classes of antifungals like azoles, echinocandins etc, copper based anti-candidal agents highlight a potential way to combat resistant candidiasis. The possibility of accumulation of NP resulting in cytotoxicity puts tamrajal as the choice due to its efficacy as well as non-toxicity as per the EPA.

Biological monitoring of workers exposed to engineered nanomaterials

As the number of nanomaterial workers increase there is need to consider whether biomonitoring of exposure should be used as a routine risk management tool. Currently, no biomonitoring of nanomaterials is mandated by authoritative or regulatory agencies. However, there is a growing knowledge base to support such biomonitoring, but further research is needed as are investigations of priorities for biomonitoring. That research should be focused on validation of biomarkers of exposure and effect. Some biomarkers of effect are generally nonspecific. These biomarkers need further interpretation before they should be used. Overall biomonitoring of nanomaterial workers may be important to supplement risk assessment and risk management efforts.

Validation of metallothionein, interleukin-8, and heme oxygenase-1 as markers for the evaluation of cytotoxicity caused by metal oxide nanoparticles

Metal oxide nanoparticles have an industrial value, although their harmful effects are also known. Induction of respiratory inflammation through their inhalation is a serious indicator of their toxicity. Although the phenomenon of metal ion release is involved in the induction of inflammation, all metal ions are not necessarily toxic. However, currently, no particular index to evaluate cytotoxicity caused by nanoparticles exists. An index based on biological response is critical. In the present study, we examined the gene expression-based index for nanoparticle-derived cytotoxicity. The cellular effects of six kinds of metal oxide nanoparticles, ZnO, NiO, CuO, MgO, Bi₂O₃, and MoO₃ on A549 cells were examined. It was seen that lactate dehydrogenase (LDH) assay, which is one of the most important assays for assessing cell membrane damage, is inhibited by metal ions released from the metal oxide nanoparticles. In some cases, enzyme activity-based assay was not suitable for the evaluation of cytotoxicity of nanoparticles. ZnO and CuO nanoparticles displayed severe cytotoxicity and enhanced gene expression of heme oxygenase-1 (HO-1) and interleukin-8 (IL-8). The IL-8 gene expression was also increased from Bi₂O₃ exposure. Additionally, the gene expression of metallothionein 2A (MT2A) was enhanced in the ZnO, CuO, and Bi₂O₃ exposed cells. These results suggest that these nanoparticles released metal ions in the cells. The enhancement of HO-1, IL-8, and MT2A gene expressions was related to the cytotoxic activity of metal oxide nanoparticles. Thus, the expression level of these genes is a good indicator of nanotoxicology of metal oxide nanoparticles.

Toxicological status of nanoparticles: What we know and what we don't know

The field of nanotechnology has grown exponentially during the last few decades, due in part to the use of nanoparticles in many manufacturing processes, as well as their potential as clinical agents for treatment of diseases and for drug delivery. This has created several new avenues by which humans can be exposed to nanoparticles. Unfortunately, investigations assessing the toxicological impacts of nanoparticles (i.e. nanotoxicity), as well as their possible risks to human health and the environment, have not kept pace with the rapid rise in their use. This has created a gap-in-knowledge and a substantial need for more research. Studies are needed to help complete our understanding of the mechanisms of toxicity of nanoparticles, as well as the mechanisms mediating their distribution and accumulation in cells and tissues and their elimination from the body. This review summarizes our knowledge on nanoparticles, including their various applications, routes of exposure, their potential toxicity and risks to human health.

Multimetallic Microparticles Increase the Potency of Rifampicin against Intracellular Mycobacterium tuberculosis

Mycobacterium tuberculosis ( M.tb) has the extraordinary ability to adapt to the administration of antibiotics through the development of resistance mechanisms. By rapidly exporting drugs from within the cytosol, these pathogenic bacteria diminish antibiotic potency and drive the presentation of drug-tolerant tuberculosis (TB). The membrane integrity of M.tb is pivotal in retaining these drug-resistant traits. Silver (Ag) and zinc oxide (ZnO) nanoparticles (NPs) are established antimicrobial agents that effectively compromise membrane stability, giving rise to increased bacterial permeability to antibiotics. In this work, biodegradable multimetallic microparticles (MMPs), containing Ag NPs and ZnO NPs, were developed for use in pulmonary delivery of antituberculous drugs to the endosomal system of M.tb-infected macrophages. Efficient uptake of MMPs by M.tb-infected THP1 cells was demonstrated using an in vitro macrophage infection model, with direct interaction between MMPs and M.tb visualized with the use of electron FIB-SEM tomography. The release of Ag NPs and ZnO NPs within the macrophage endosomal system increased the potency of the model antibiotic rifampicin by as much as 76%, realized through an increase in membrane disorder of intracellular M.tb. MMPs were effective at independently driving membrane destruction of extracellular bacilli located at the exterior face of THP1 macrophages. This MMP system presents as an effective drug delivery vehicle that could be used for the transport of antituberculous drugs such as rifampicin to infected alveolar macrophages, while increasing drug potency. By increasing M.tb membrane permeability, such a system may prove effectual in improving treatment of drug-susceptible TB in addition to M.tb strains considered drug-resistant.

Quantitative human health risk assessment along the lifecycle of nano-scale copper-based wood preservatives

The use of nano-scale copper oxide (CuO) and basic copper carbonate (Cu₂(OH)₂CO₃) in both ionic and micronized wood preservatives has raised concerns about the potential of these substances to cause adverse humans health effects. To address these concerns, we performed quantitative (probabilistic) human health risk assessment (HHRA) along the lifecycles of these formulations used in antibacterial and antifungal wood coatings and impregnations by means of the EU FP7 SUN project's Decision Support System (SUNDS, www.sunds.gd). The results from the risk analysis revealed inhalation risks from CuO in exposure scenarios involving workers handling dry powders and performing sanding operations as well as potential ingestion risks for children exposed to nano Cu₂(OH)₂CO₃ in a scenario involving hand-to-mouth transfer of the substance released from impregnated wood. There are, however, substantial uncertainties in these results, so some of the identified risks may stem from the safety margin of extrapolation to fill data gaps and might be resolved by additional testing. Our stochastic approach successfully communicated the contribution of different sources of uncertainty in the risk assessment. The main source of uncertainty was the extrapolation from short to long-term exposure, which was necessary due to the lack of (sub)chronic in vivo studies with CuO and Cu₂(OH)₂CO₃. Considerable uncertainties also stemmed from the use of default inter- and intra-species extrapolation factors.

Nanocolloids in Natural Water: Isolation, Characterization, and Toxicity

Nanocolloids are widespread in natural water systems, but their characterization and ecological risks are largely unknown. Herein, tangential flow ultrafiltration (TFU) was used to separate and concentrate nanocolloids from surface waters. Unexpectedly, nanocolloids were present in high concentrations ranging from 3.7 to 7.2 mg/L in the surface waters of the Harihe River in Tianjin City, China. Most of the nanocolloids were 10-40 nm in size, contained various trace metals and polycyclic aromatic hydrocarbons, and exhibited fluorescence properties. Envelopment effects and aggregation of Chlorella vulgaris in the presence of nanocolloids were observed. Nanocolloids entered cells and nanocolloid-exposed cells exhibited stronger plasmolysis, chloroplast damage and more starch grains than the control cells. Moreover, nanocolloids inhibited the cell growth, promoted reactive oxygen species (ROS), reduce the chlorophyll a content and increased the cell permeability. The genotoxicity of nanocolloids was also observed. The metabolomics analysis revealed a significant ( p < 0.05) downregulation of amino acids and upregulation of fatty acids contributing to ROS increase, chlorophyll a decrease and plasmolysis. The present work reveals that nanocolloids, which are different from specific, engineered nanoparticles (e.g., Ag nanoparticles), are present at high concentrations, exhibit an obvious toxicity in environments, and deserve more attention in the future.

Assessment of copper nanoparticles (Cu-NPs) and copper (II) oxide (CuO) induced hemato- and hepatotoxicity in Cyprinus carpio

Recently, Cu-based nanoparticles have drawn considerable attention for their various fascinating roles in multiple biological systems. It is recognized that their frequent use can create compatibility challenges for the recipient systems. Nevertheless, it is unclear how various biological interactions affect the compatibility of Cu oxide II (CuO) and Cu oxide nanoparticles (Cu-NPs) for different organisms. Consequently, it has been difficult to perform structured risk assessments for their use in biological systems. Therefore, this study compared the effects of different doses of waterborne Cu-NPs and CuO on the blood and liver of selected groups of Cyprinus (C) carpio. These fish while housed in suitable water tanks were exposed to one of the following treatments for 14 d: control (no added Cu) or 0.5 or 1 or 1.5 mg Cu as Cu-NPs or CuO l^-1 of water. We found significant changes in all assessed blood parameters of fish in response to increasing doses from 0 to 1.5 mg of Cu-NPs or CuO. Similarly, increased levels of lipid peroxide and reduced glutathione (GSH) were also observed in the livers of C. carpio in Cu-NPs or CuO treated groups. Enhanced levels of lipid peroxidation and GSH were also recorded in the Cu-NP treated groups compared with the CuO treated groups in a dose dependent manner. The lowest catalase activity was observed in the liver of C. carpio treated with the higer dose of Cu-NPs. Cu-NP or CuO exposure induced significant histological alterations in the liver of C. carpio including focal necrosis, cloudy swelling of hepatocytes, degenerative hepatocytes, vacuolization, pyknotic nuclei, damaged central vein, nuclear hypertrophy, dilated sinusoid, vacuolated degeneration, congestion, and complete degeneration in a dose dependent manner. Substantial alterations in blood and liver specimens were observed in the Cu-NP treated fish when compared with the CuO treated fish. It appeared that the Cu-NPs were more toxic than the CuO as shown by the hemato- and hepatotoxicity in C. carpio of this study.

Toxicity of surface-modified copper oxide nanoparticles in a mouse macrophage cell line: Interplay of particles, surface coating and particle dissolution

The rapid dissolution of copper oxide (CuO) nanoparticles (NPs) with release of ions is thought to be one of the main factors modulating their toxicity. Here we assessed the cytotoxicity of a panel of CuO NPs (12 nm ± 4 nm) with different surface modifications, i.e., anionic sodium citrate (CIT) and sodium ascorbate (ASC), neutral polyvinylpyrrolidone (PVP), and cationic polyethylenimine (PEI), versus the pristine (uncoated) NPs, using a murine macrophage cell line (RAW264.7). Cytotoxicity, reactive oxygen species (ROS) production, and cellular uptake were assessed. The cytotoxicity results were analyzed by the benchmark dose (BMD) method and the NPs were ranked based on BMD₂₀ values. The PEI-coated NPs were found to be the most cytotoxic. Despite the different properties of the coating agents, NP dissolution in cell medium was only marginally affected by surface modification. Furthermore, CuCl₂ (used as an ion control) elicited significantly less cytotoxicity when compared to the CuO NPs. We also observed that the antioxidant, N-acetylcysteine, failed to protect against the cytotoxicity of the uncoated CuO NPs. Indeed, the toxicity of the surface-modified CuO NPs was not directly linked to particle dissolution and subsequent Cu burden in cells, nor to cellular ROS production, although CuO-ASC NPs, which were found to be the least cytotoxic, yielded lower levels of ROS in comparison to pristine NPs. Hierarchical cluster analysis suggested, instead, that the toxicity in the current in vitro model could be explained by synergistic interactions between the NPs, their dissolution, and the toxicity of the coating agents.

Intranasal Delivery of Copper Oxide Nanoparticles Induces Pulmonary Toxicity and Fibrosis in C57BL/6 mice

Copper oxide nanoparticles (CuO NPs) are widely used as catalysts or semiconductors in material fields. Recent studies have suggested that CuO NPs have adverse genotoxicity and cytotoxicity effects on various cells. However, little is known about the toxicity of CuO NPs following exposure to murine lungs. The purpose of this fundamental research was to investigate whether CuO NPs could induce epithelial cell injury, pulmonary inflammation, and eventually fibrosis in C57BL/6 mice. Our studies showed that CuO NPs aggravated pulmonary inflammation in a dose-dependent manner. CuO NPs induced apoptosis of epithelial cells as indicated by TUNEL staining, flow cytometry and western blot analysis, which was partially caused by increased reactive oxygen species (ROS). In addition, CuO NPs exposure promoted collagen accumulation and expression of the progressive fibrosis marker α-SMA in the lung tissues, indicating that CuO NP inhalation could induce pulmonary fibrosis in C57BL/6 mice. All data provide novel evidence that there is an urgent need to prevent the adverse effects of CuO NPs in the human respiratory system.

Biosorption: An Interplay between Marine Algae and Potentially Toxic Elements-A Review

In recent decades, environmental pollution has emerged as a core issue, around the globe, rendering it of fundamental concern to eco-toxicologists, environmental biologists, eco-chemists, pathologists, and researchers from other fields. The dissolution of polluting agents is a leading cause of environmental pollution of all key spheres including the hydrosphere, lithosphere, and biosphere, among others. The widespread occurrence of various pollutants including toxic heavy metals and other emerging hazardous contaminants is a serious concern. With increasing scientific knowledge, socioeconomic awareness, human health problems, and ecological apprehensions, people are more concerned about adverse health outcomes. Against this background, several removal methods have been proposed and implemented with the aim of addressing environmental pollution and sustainable and eco-friendly development. Among them, the biosorption of pollutants using naturally inspired sources, e.g., marine algae, has considerable advantages. In the past few years, marine algae have been extensively studied due to their natural origin, overall cost-effective ratio, and effectiveness against a broader pollutant range; thus, they are considered a potential alternative to the conventional methods used for environmental decontamination. Herein, an effort has been made to highlight the importance of marine algae as naturally inspired biosorbents and their role in biosorption. Biosorption mechanisms and factors affecting biosorption activities are also discussed in this review. The utilization of marine algae as a biosorbent for the removal of numerous potentially toxic elements has also been reviewed.

Transformations of Nanoenabled Copper Formulations Govern Release, Antifungal Effectiveness, and Sustainability throughout the Wood Protection Lifecycle

Here we compare the standard European benchmark of wood treatment by molecularly dissolved copper amine (Cu-amine), also referred to as aqueous copper amine (ACA), against two nanoenabled formulations: copper(II)oxide nanoparticles (CuO NPs) in an acrylic paint to concentrate Cu as a barrier on the wood surface, and a suspension of micronized basic copper carbonate (CuCO₃·Cu(OH)₂) for wood pressure treatment. After characterizing the properties of the (nano)materials and their formulations, we assessed their effects in vitro against three fungal species: Coniophora puteana, Gloeophyllum trabeum, and Trametes versicolor, finding them to be mediated only partially by ionic transformation. To assess the use phase, we quantify both release rate and form. Cu leaching rates for the two types of impregnated wood (conventional and nanoenabled) are not significantly different at 172 ± 6 mg/m², with Cu being released predominantly in ionic form. Various simulations of outdoor aging with release sampling by runoff, during condensation, by different levels of mechanical shear, all resulted in comparable form and rate of release from the nanoenabled or the molecular impregnated woods. Because of dissolving transformations, the nanoenabled impregnation does not introduce additional concern over and above that associated with the traditional impregnation. In contrast, Cu released from wood coated with the CuO acrylate contained particles, but the rate was at least 100-fold lower. In the same ranking, the effectiveness to protect against the wood-decaying basidiomycete Coniophora puteana was significant with both impregnation technologies but remained insignificant for untreated wood and wood coated by the acrylic CuO. Accordingly, a lifecycle-based sustainability analysis indicates that the CuO acrylic coating is less sustainable than the technological alternatives, and should not be developed into a commercial product.

Copper oxide nanoparticles induce collagen deposition via TGF-β1/Smad3 signaling in human airway epithelial cells

Use and application of nanoparticles has increased in recent years. Copper oxide nanoparticles (CuONPs) are one of the most common types of nanoparticles, and they are mainly used as catalysts and preservatives. However, limited toxicity data are available on the toxicity of CuONPs to the respiratory system. We investigated fibrotic responses induced by CuONPs in the respiratory tract and elucidated its underlying mechanism of action in vivo and in vitro experiments. In the mouse model, CuONPs exposure markedly increased transforming growth factor-β1 (TGF-β1) and collagen I expression and Smad3 phosphorylation, combined with elevation of inflammatory mediators including interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α). These alterations were also observed in histological analysis of lung tissue. CuONPs markedly increased inflammatory responses and collagen deposition, accompanied by the elevation of TGF-β1 and collagen I expression in lung tissue. In addition, CuONPs-treated H292 cells showed significantly increased mRNA and protein production of TGF-β1, collagen I, IL-6, and TNF-α; this response was markedly decreased by treatment of a TGF-β1 inhibitor (SB-431542). Taken together, CuONPs induced fibrotic responses in the respiratory tract, closely related to TGF-β1/Smad3 signaling. Therefore, our results raise the necessity of further investigation for the present state of its risk by providing useful information of the toxicity of CuONPs.

ISD3: a particokinetic model for predicting the combined effects of particle sedimentation, diffusion and dissolution on cellular dosimetry for in vitro systems

BACKGROUND

The development of particokinetic models describing the delivery of insoluble or poorly soluble nanoparticles to cells in liquid cell culture systems has improved the basis for dose-response analysis, hazard ranking from high-throughput systems, and now allows for translation of exposures across in vitro and in vivo test systems. Complimentary particokinetic models that address processes controlling delivery of both particles and released ions to cells, and the influence of particle size changes from dissolution on particle delivery for cell-culture systems would help advance our understanding of the role of particles and ion dosimetry on cellular toxicology. We developed ISD3, an extension of our previously published model for insoluble particles, by deriving a specific formulation of the Population Balance Equation for soluble particles.

RESULTS

ISD3 describes the time, concentration and particle size dependent dissolution of particles, their delivery to cells, and the delivery and uptake of ions to cells in in vitro liquid test systems. We applied the model to calculate the particle and ion dosimetry of nanosilver and silver ions in vitro after calibration of two empirical models, one for particle dissolution and one for ion uptake. Total media ion concentration, particle concentration and total cell-associated silver time-courses were well described by the model, across 2 concentrations of 20 and 110 nm particles. ISD3 was calibrated to dissolution data for 20 nm particles as a function of serum protein concentration, but successfully described the media and cell dosimetry time-course for both particles at all concentrations and time points. We also report the finding that protein content in media affects the initial rate of dissolution and the resulting near-steady state ion concentration in solution for the systems we have studied.

CONCLUSIONS

By combining experiments and modeling, we were able to quantify the influence of proteins on silver particle solubility, determine the relative amounts of silver ions and particles in exposed cells, and demonstrate the influence of particle size changes resulting from dissolution on particle delivery to cells in culture. ISD3 is modular and can be adapted to new applications by replacing descriptions of dissolution, sedimentation and boundary conditions with those appropriate for particles other than silver.

Suppression of PTPN6 exacerbates aluminum oxide nanoparticle-induced COPD-like lesions in mice through activation of STAT pathway

Background

Inhaled nanoparticles can deposit in the deep lung where they interact with pulmonary cells. Despite numerous studies on pulmonary nanotoxicity, detailed molecular mechanisms of specific nanomaterial-induced lung injury have yet to be identified.

Results

Using whole-body dynamic inhalation model, we studied the interactions between aluminum oxide nanoparticles (Al₂O₃ NPs) and the pulmonary system in vivo. We found that seven-day-exposure to Al₂O₃ NPs resulted in emphysema and small airway remodeling in murine lungs, accompanied by enhanced inflammation and apoptosis. Al₂O₃ NPs exposure led to suppression of PTPN6 and phosphorylation of STAT3, culminating in increased expression of the apoptotic marker PDCD4. Rescue of PTPN6 expression or application of a STAT3 inhibitor, effectively protected murine lungs from inflammation and apoptosis, as well as, in part, from the induction of chronic obstructive pulmonary disease (COPD)-like effects.

Conclusion

In summary, our studies show that inhibition of PTPN6 plays a critical role in Al₂O₃ NPs-induced COPD-like lesions.

Electronic supplementary material

The online version of this article (10.1186/s12989-017-0234-0) contains supplementary material, which is available to authorized users.

The inflammatory response to silver and titanium dioxide nanoparticles in the central nervous system

Despite the increasing number of neurotoxicological studies on metal-containing nanoparticles (NPs), the NP-induced neuroinflammation has not yet been well understood. This review provides a comprehensive understanding of inflammatory responses to two typical metal-containing NPs, namely silver NPs (Ag-NPs) and titanium dioxide NPs (TiO₂-NPs). Ag-NPs and TiO₂-NPs could translocate into the CNS through damaged blood-brain barrier, nerve afferent signaling and eye-to-brain ways, and even cell uptake. NPs could stimulate the activation of glial cells to release proinflammatory cytokines and generate reactive oxygen species and nitric oxide production, resulting in the neuroinflammation. The potential mechanisms of Ag-NPs and TiO₂-NPs causing inflammation are complex, including several immune response relevant signaling pathways. Some parameters governing their ability to cause neuroinflammation are presented as well.

Transcriptional profiling reveals gene expression changes associated with inflammation and cell proliferation following short-term inhalation exposure to copper oxide nanoparticles

Our recent studies revealed a dose-dependent proinflammatory response to copper oxide nanoparticles (CuO NPs) in rats following short-term inhalation exposure for five consecutive days. Here transcriptomics approaches were applied using the same model to assess global gene expression in lung tissues obtained 1 day post-exposure and after a recovery period of 22 days from rats exposed to clean air or 6 hour equivalent doses of 3.3 mg m^-3 (low dose) and 13.2 mg m^-3 (high dose). Microarray analyses yielded about 1000 differentially expressed genes in the high-dose group and 200 in low-dose compared to the clean air control group, and less than 20 after the recovery period. Pathway analysis indicated cell proliferation/survival and inflammation as the main processes triggered by exposure to CuO NPs. We did not find significant perturbations of pathways related to oxidative stress. Upregulation of epithelial cell transforming protein 2 (Ect2), a known oncogene, was noted and ECT2 protein was upregulated in the lungs of exposed animals. Proliferation of alveolar epithelial cells was demonstrated based on Ki67 expression. The gene encoding monocyte chemoattractant protein 1 (or CCL2) was also upregulated and this was confirmed by immunohistochemistry. However, no aberrant DNA methylation of inflammation-associated genes was observed. In conclusion, we have found that inhalation of CuO NPs in rats causes upregulation of the oncoprotein ECT2 and the chemokine CCL2 and other proinflammatory markers as well as proliferation in bronchoalveolar epithelium after a short-term inhalation exposure. Thus, pathways known to be associated with neoplastic processes and inflammation were affected in this model.

Impact of copper oxide nanomaterials on differentiated and undifferentiated Caco-2 intestinal epithelial cells; assessment of cytotoxicity, barrier integrity, cytokine production and nanomaterial penetration

BACKGROUND

Copper oxide nanomaterials (CuO NMs) are exploited in a diverse array of products including antimicrobials, inks, cosmetics, textiles and food contact materials. There is therefore a need to assess the toxicity of CuO NMs to the gastrointestinal (GI) tract since exposure could occur via direct oral ingestion, mucocillary clearance (following inhalation) or hand to mouth contact.

METHODS

Undifferentiated Caco-2 intestinal cells were exposed to CuO NMs (10 nm) at concentrations ranging from 0.37 to 78.13 μg/cm2 Cu (equivalent to 1.95 to 250 μg/ml) and cell viability assessed 24 h post exposure using the alamar blue assay. The benchmark dose (BMD 20), determined using PROAST software, was identified as 4.44 μg/cm2 for CuO NMs, and 4.25 μg/cm2 for copper sulphate (CuSO4), which informed the selection of concentrations for further studies. The differentiation status of cells and the impact of CuO NMs and CuSO4 on the integrity of the differentiated Caco-2 cell monolayer were assessed by measurement of trans-epithelial electrical resistance (TEER), staining for Zonula occludens-1 (ZO-1) and imaging of cell morphology using scanning electron microscopy (SEM). The impact of CuO NMs and CuSO4 on the viability of differentiated cells was performed via assessment of cell number (DAPI staining), and visualisation of cell morphology (light microscopy). Interleukin-8 (IL-8) production by undifferentiated and differentiated Caco-2 cells following exposure to CuO NMs and CuSO4 was determined using an ELISA. The copper concentration in the cell lysate, apical and basolateral compartments were measured with Inductive Coupled Plasma Optical Emission Spectrometry (ICP-OES) and used to calculate the apparent permeability coefficient (Papp); a measure of barrier permeability to CuO NMs. For all experiments, CuSO4 was used as an ionic control.

RESULTS

CuO NMs and CuSO4 caused a concentration dependent decrease in cell viability in undifferentiated cells. CuO NMs and CuSO4 translocated across the differentiated Caco-2 cell monolayer. CuO NM mediated IL-8 production was over 2-fold higher in undifferentiated cells. A reduction in cell viability in differentiated cells was not responsible for the lower level of cytokine production observed. Both CuO NMs and CuSO4 decreased TEER values to a similar extent, and caused tight junction dysfunction (ZO-1 staining), suggesting that barrier integrity was disrupted.

CONCLUSIONS

CuO NMs and CuSO4 stimulated IL-8 production by Caco-2 cells, decreased barrier integrity and thereby increased the Papp and translocation of Cu. There was no significant enhancement in potency of the CuO NMs compared to CuSO4. Differentiated Caco-2 cells were identified as a powerful model to assess the impacts of ingested NMs on the GI tract.

Silver nanoparticles inhaled during pregnancy reach and affect the placenta and the foetus

Recently, interest for the potential impact of consumer-relevant engineered nanoparticles on pregnancy has dramatically increased. This study investigates whether inhaled silver nanoparticles (AgNPs) reach and cross mouse placental barrier and induce adverse effects. Apart from their relevance for the growing use in consumer products and biomedical applications, AgNPs are selected since they can be unequivocally identified in tissues. Pregnant mouse females are exposed during the first 15 days of gestation by nose-only inhalation to a freshly produced aerosol of 18-20 nm AgNPs for either 1 or 4 h, at a particle number concentration of 3.80 × 107 part./cm^-3 and at a mass concentration of 640 μg/m³. AgNPs are identified and quantitated in maternal tissues, placentas and foetuses by transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy and single-particle inductively coupled plasma mass spectrometry. Inhalation of AgNPs results in increased number of resorbed foetuses associated with reduced oestrogen plasma levels, in the 4 h/day exposed mothers. Increased expression of pregnancy-relevant inflammatory cytokines is also detected in the placentas of both groups. These results prove that NPs are able to reach and cross the mouse placenta and suggest that precaution should be taken with respect to acute exposure to nanoparticles during pregnancy.