Pulmonary toxicity and translocation of gallium phosphide nanowires to secondary organs following pulmonary exposure in mice.

BACKGROUND: III-V semiconductor nanowires are envisioned as being integrated in optoelectronic devices in the near future. However, the perspective of mass production of these nanowires raises concern for human safety due to their asbestos- and carbon nanotube-like properties, including their high aspect ratio shape. Indeed, III-V nanowires have similar dimensions as Mitsui-7 multi-walled carbon nanotubes, which induce lung cancer by inhalation in rats. It is therefore urgent to investigate the toxicological effects following lung exposure to III-V nanowires prior to their use in industrial production, which entails risk of human exposure. Here, female C57BL/6J mice were exposed to 2, 6, and 18 µg (0.12, 0.35 and 1.1 mg/kg bw) of gallium phosphide (III-V) nanowires (99 nm diameter, 3.7 µm length) by intratracheal instillation and the toxicity was investigated 1, 3, 28 days and 3 months after exposure. Mitsui-7 multi-walled carbon nanotubes and carbon black Printex 90 nanoparticles were used as benchmark nanomaterials. RESULTS: Gallium phosphide nanowires induced genotoxicity in bronchoalveolar lavage cells and acute inflammation with eosinophilia observable both in bronchoalveolar lavage and lung tissue (1 and 3 days post-exposure). The inflammatory response was comparable to the response following exposure to Mitsui-7 multi-walled carbon nanotubes at similar dose levels. The nanowires underwent partial dissolution in the lung resulting in thinner nanowires, with an estimated in vivo half-life of 3 months. Despite the partial dissolution, nanowires were detected in lung, liver, spleen, kidney, uterus and brain 3 months after exposure. CONCLUSION: Pulmonary exposure to gallium phosphide nanowires caused similar toxicological effects as the multi-walled carbon nanotube Mitsui-7.

Quantifying the relative contribution of particulate versus dissolved silver to toxicity and uptake kinetics of silver nanowires in lettuce: impact of size and coating.

Functionalized high-aspect-ratio silver nanowires (AgNWs) have been recognized as one of the most promising alternatives for fabricating products, with their use ranging from electronic devices to biomedical fields. Given concerns on the safety of AgNWs, there is an urgent need to investigate the relation between intrinsic properties of AgNWs and their toxicity. In this study, lettuce was exposed for either 6 or 18 d to different AgNWs to determine how the size/aspect ratio and coating of AgNWs affect the contributions of the dissolved and particulate Ag to the overall phytotoxicity and uptake kinetics. We found that the uncoated AgNW (39 nm diameter × 8.4 µm length) dissolved fastest of all AgNWs investigated. The phytotoxicity, uptake rate constants, and bioaccumulation factors of the PVP-coated AgNW (43 nm diameter × 1.8 µm length) and the uncoated AgNW (39 nm diameter × 8.4 µm length) were similar, and both were higher than that of the PVP-coated AgNW with the larger diameter(65 nm diameter × 4.4 µm length). These results showed that the diameter of the AgNWs predominantly affected toxicity and Ag accumulation in plants. Particulate Ag was found to be the predominant driver/descriptor of overall toxicity and Ag accumulation in the plants rather than dissolved Ag for all AgNWs tested. The relative contribution of dissolved versus particulate Ag to the overall effects was influenced by the exposure concentration and the extent of dissolution of AgNWs. This work highlights inherent particulate-dependent effects of AgNWs in plants and suggests that toxicokinetics should explicitly be considered for more nanomaterials and organisms, consequently providing more realistic input information for their environmental risk assessment.

Evaluation of the toxicity of nickel nanowires to freshwater organisms at concentrations and short-term exposures compatible with their application in water treatment.

In order to understand the potential impacts of nickel nanowires (Ni NWs) after reaching the aquatic environment, this research evaluated the toxicity of Ni NWs with different lengths (≤ 1.1, ≤11 and ≤ 80 µm) for several floating, planktonic and nektonic freshwater organisms. In this work, Ni NWs were synthesized by electrodeposition using anodized aluminum oxide (AAO) membranes. The toxicity of the NWs was assessed using a battery of aquatic species representative of key functions at the ecosystem level: the bacterium Aliivibrio fischeri, the algae Raphidocelis subcapitata, the macrophyte Lemna minor, the crustacean Daphnia magna and the zebrafish Danio rerio. Results indicated that for the concentrations tested (up to 2.5 mg L-1) the synthesized Ni NWs showed low toxicity. And although no lethal toxicity was observed for D. magna, at a sublethal level the feeding activity of the freshwater cladoceran was severely affected after exposure to Ni NWs. These findings showed that NWs can be accumulated in the gut of D. magna, even during a short exposure (24 h) directly impairing Daphnia nutrition and eventually populations growth. Consequently, this can also contribute to trophic transfer of NWs along the food chain. According to our results the toxicity of Ni NW may be mainly attributed to physical effects rather than chemical effects of Ni ions, considering that the concentrations of Ni NWs tested in this study were well below the toxicity thresholds reported in the literature for Ni ions and for Ni NMs.

An in vivo study of nanorod, nanosphere, and nanowire forms of titanium dioxide using Drosophila melanogaster: toxicity, cellular uptake, oxidative stress, and DNA damage.

The biological impact of nanomaterials (NMs) is determined by several factors such as size and shape, which need to be taken into consideration in any type of analysis. While investigators often prefer to conduct in vitro studies for detection of any possible adverse effects of NMs, in vivo approaches yield more relevant data for risk assessment. For this reason, Drosophila melanogaster was selected as a suitable in vivo model to characterize the potential risks associated with exposure nanorods (NRs), nanospheres (NSs), nanowires (NWs) forms of titanium dioxide (TiO2), and their microparticulated (or bulk) form, as TiO2. Third instar larvae (72 hr old larvae) were fed with TiO2 (NRs, NSs, or NWs) and TiO2 at concentrations ranging from 0.01 to 10 mM. Viability (toxicity), internalization (cellular uptake), intracellular reactive oxygen species (ROS) production, and genotoxicity (Comet assay) were the end-points evaluated in hemocyte D. melanogaster larvae. Significant intracellular oxidative stress and genotoxicity were noted at the highest exposure concentration (10 mM) of TiO2 (NRs, NSs, or NWs), as determined by the Comet assay and ROS analysis, respectively. A concentration-effect relationship was observed in hemocytes exposed to the NMs. Data demonstrated that selected forms of TiO2.-induced genotoxicity in D. melanogaster larvae hemocytes indicating this organism is susceptible for use as a model to examine in vivo NMs-mediated effects.

Cytotoxicity and internalization analysis of silicon nanowires in Buffalo Green Monkey cells: a preliminary study to evaluate the possibility of carrying viruses inside the cells.

Silicon nanowires (SiNWs) are attractive functional nanomaterials for biomedical applications. The ability to easily tune their size and density, potential biocompatibility, and knowledge of the chemical activation of SiNWs surface make them natural tools to interact with biological materials. We evaluated the possibility of exploiting SiNWs as carriers to introduce organic compounds into cells. The cellular toxicity and the internalization capacity of free-standing and label-free SiNWs were tested on Buffalo Green Monkey cells (BGM). Confocal fluorescent observation of SiNWs conjugated with fluorescein-polyethylene imine (PEI) confirmed the internalization of the NWs into the Buffalo Green Monkey Cells (BGM).

Evaluation of Antibacterial and Cytotoxicity Properties of Silver Nanowires and Their Composites with Carbon Nanotubes for Biomedical Applications.

In this work, we prepared silver nanowires (AgNWs) via the polyol method in the presence or absence of single wall carbon nanotubes (CNTs) and tested their physicochemical, antibacterial and cytotoxic properties. Results showed that the introduction of CNTs lead to the formation of AgNWs at lower temperature, but the final product characteristics of AgNWs and AgNWs-CNT were not significantly different. AgNWs exhibited antibacterial properties against all the studied bacterial species via the formation of oxygen reactive species (ROS) and membrane damage. Furthermore, AgNWs exhibited a dose-dependent and time-dependent toxicity at concentrations ≥ 10 µg/mL. Fibroblasts appeared to be more resistant than human colorectal adenocarcinoma (Caco-2) and osteoblasts to the toxicity of AgNWs. The cytotoxicity of AgNWs was found to be related to the formation of ROS, but not to membrane damage. Overall, these results suggest that AgNWs are potential antibacterial agents against E. coli, S. aureus, MRSA and S. saprophyticus, but their dosage needs to be adjusted according to the route of administration.

Ultralong AgNWs-induced toxicity in A549 cells and the important roles of ROS and autophagy.

Safety concerns have been raised with regard to silver nanowires (AgNWs) because of their extensive applications. Recently, ultralong AgNWs have shown physical properties superior to those of short AgNWs. However, little is known about their toxicity and potential risks. In this study, we demonstrated a series of ultralong AgNWs-induced biological effects in human lung cancer epithelial cells (A549). Ultralong AgNWs treatments induced ROS generation, mitochondria-mediated apoptosis, and self-protective autophagy at nonlethal concentrations. In contrast to some previous reports, apoptosis was found not to correlate with the reduction of intracellular ROS. Measuring the processing of ROS generation, apoptosis and autophagy, we demonstrated that ROS not only enhance mitochondrial damage, but also raise protective autophagic flux in ultralong AgNW-treated cells. Moreover, ultralong AgNWs were found to be internalized into the cytoplasm of the epithelial cells. This study not only investigates ultralong AgNWs-induced cytotoxicity but also pinpoints ROS as a key signal in mechanisms of their toxicity.

Length and diameter-dependent phagocytosis and cytotoxicity of long silver nanowires in macrophages.

Long silver nanowires (AgNWs, >5 µm) have shown promising applications in next generation biomaterials. However, the toxicity of long AgNWs is not well characterized in terms of their size. In this study, five AgNWs types, including SAgNW30 (length: 5-10 µm; diameter: 30 nm), MAgNW30 (length: 20-30 µm; diameter: 30 nm), LAgNW30 (length: ∼100 µm; diameter: 30 nm), LAgNW50 (length: ∼100 µm; diameter: 50 nm), and LAgNW100 (length: ∼100 µm; diameter: 100 nm), were used to investigate the size-dependent phagocytosis and cytotoxicity in macrophage. It showed that SAgNW30, MAgNW30, LAgNW30 can be fully phagocytosed by macrophages, but LAgNW50 and LAgNW100 frustrated the phagocytosis. It demonstrated that LAgNW30 can be internalized into macrophage in a curly manner. The size-dependent cytotoxicity was observed in cell viability, apoptosis, mitochondrial damage, phenotypic transition, and inflammatory response in AgNWs-treated macrophage. The AgNWs-induced cytotoxicity was depended on their length and diameter, increased gradually in the order of SAgNW30 > MAgNW30 > LAgNW30 > LAgNW50 > LAgNW100. The findings presented here will assist in the evaluation of the size-dependent cytotoxicity mediated by long AgNWs.

Crumpling of silver nanowires by endolysosomes strongly reduces toxicity.

Fibrous particles interact with cells and organisms in complex ways that can lead to cellular dysfunction, cell death, inflammation, and disease. The development of conductive transparent networks (CTNs) composed of metallic silver nanowires (AgNWs) for flexible touchscreen displays raises new possibilities for the intimate contact between novel fibers and human skin. Here, we report that a material property, nanowire-bending stiffness that is a function of diameter, controls the cytotoxicity of AgNWs to nonimmune cells from humans, mice, and fish without deterioration of critical CTN performance parameters: electrical conductivity and optical transparency. Both 30- and 90-nm-diameter AgNWs are readily internalized by cells, but thinner NWs are mechanically crumpled by the forces imposed during or after endocytosis, while thicker nanowires puncture the enclosing membrane and release silver ions and lysosomal contents to the cytoplasm, thereby initiating oxidative stress. This finding extends the fiber pathology paradigm and will enable the manufacture of safer products incorporating AgNWs.

Nanowarming using Au-tipped Co35Fe65 ferromagnetic nanowires.

Ferromagnetic Co35Fe65, Fe, Co, and Ni nanowires have high saturation magnetizations (Ms) and magnetic anisotropies, making them ideal for magnetic heating in an alternating magnetic field (AMF). Here, Au-tipped nanowires were coated with polyethylene glycol (PEG) and specific absorption rates (SAR) were measured in glycerol. SAR increased when using metals with increasing Ms (Co35Fe65 > Fe > Co > Ni), reaching 1610 ± 20 W g-1 metal at 1 mg metal per ml glycerol for Co35Fe65 nanowires using 190 kHz and 20 kA m-1. Aligning these nanowires parallel to the AMF increased SAR up to 2010 W g-1 Co35Fe65. Next, Co35Fe65 nanowires were used to nanowarm vitrified VS55, a common cryoprotective agent (CPA).Nanowarming rates up to 1000 °C min-1 (5 mg Co35Fe65 per ml VS55) were achieved, which is 20× faster than the critical warming rate (50 °C min-1) for VS55 and other common CPAs. Human dermal fibroblast cells exposed to VS55, and Co35Fe65 nanowire concentrations of 0, 1 and 2.5 mg Fe per ml all showed similar cell viability, indicating that the nanowires had minimal cytotoxicity. With the ability to provide rapid and uniform heating, ferromagnetic nanowires have excellent potential for nanowarming cryopreserved tissues.

In vitro exposure of a 3D-tetraculture representative for the alveolar barrier at the air-liquid interface to silver particles and nanowires.

BACKGROUND: The present study aimed to evaluate the potential differences in the biological effects of two types of spherical silver particles of 20 and 200 nm (Ag20 and Ag200), and of PVP-coated silver nanowires (AgNWs) with a diameter of 50 nm and length up to 50 µm, using a complex 3D model representative for the alveolar barrier cultured at air-liquid interface (ALI). The alveolar model was exposed to 0.05, 0.5 and 5 µg/cm2 of test compounds at ALI using a state-of-the-art exposure system (Vitrocell™Cloud System). Endpoints related to the oxidative stress induction, anti-oxidant defence mechanisms, pro-inflammatory responses and cellular death were selected to evaluate the biocompatibility of silver particles and nanowires (AgNMs) and to further ascribe particular biological effects to the different morphologic properties between the three types of AgNMs evaluated. RESULTS: Significant cytotoxic effect was observed for all three types of AgNMs at the highest tested doses. The increased mRNA levels of the pro-apoptotic gene CASP7 suggests that apoptosis may occur after exposure to AgNWs. All three types of AgNMs increased the mRNA level of the anti-oxidant enzyme HMOX-1 and of the metal-binding anti-oxidant metallothioneins (MTs), with AgNWs being the most potent inducer. Even though all types of AgNMs induced the nuclear translocation of NF-kB, only AgNWs increased the mRNA level of pro-inflammatory mediators. The pro-inflammatory response elicited by AgNWs was further confirmed by the increased secretion of the 10 evaluated interleukins. CONCLUSION: In the current study, we demonstrated that the direct exposure of a complex tetra-culture alveolar model to different types of AgNMs at ALI induces shape- and size-specific biological responses. From the three AgNMs tested, AgNWs were the most potent in inducing biological alterations. Starting from 50 ng/cm2, a dose representative for an acute exposure in a high exposure occupational setting, AgNWs induced prominent changes indicative for a pro-inflammatory response. Even though the acute responses towards a dose representative for a full-lifetime exposure were also evaluated, chronic exposure scenarios at low dose are still unquestionably needed to reveal the human health impact of AgNMs during realistic conditions.

Preparation of Au@Ag core-shell nanoparticle decorated silicon nanowires for bacterial capture and sensing combined with laser induced breakdown spectroscopy and surface-enhanced Raman spectroscopy.

Three-dimensional nano-biointerfaces, emerging as significant cell-guiding platforms, have attracted great attention. Nevertheless, complicated chemical modifications and instability of bio-ligands limit their widespread application. In this study, a novel biointerface, based on silicon nanowires (SiNWs) array, was prepared for bacterial capture and sensing. Vertically aligned SiNWs were fabricated via metal assisted chemical etching and decorated with uniform Au@Ag core-shell nanoparticles (Au@Ag NPs). These deposited Au@Ag NPs formed multi-scale topographic structures with nanowires, which provided effective attachment sites for bacterial adhesins. In addition, the Au cores of Au@Ag NPs enhanced the activity of the surface silver atoms and promoted the binding of Au@Ag NPs to bacteria. Thus, the Au@Ag NPs decorated SiNWs (SiNWs-Au@Ag) substrate exhibited high capture capacity for bacteria in drinking water (8.6 and 5.5 × 106 cells per cm2 for E. coli and S. aureus in 40 min, respectively) via physical and chemical effects. Bacteria in drinking water can be sensitively detected by using a combination of laser induced breakdown spectroscopy (LIBS) and label based surface-enhanced Raman spectroscopy (SERS) techniques. Due to the antibacterial activity of Au@Ag NPs and the physical stress exerted on SiNWs, the prepared biointerface also showed high antibacterial rates towards both Gram-positive and Gram-negative bacteria strains. With these excellent properties, the flexible sensing platform might open a new avenue for the prevention and control of microbial hazards in water.

Ultra-long silver nanowires induced mitotic abnormalities and cytokinetic failure in A549 cells.

Asbestos fiber has been associated with mesothelioma and lung cancer. However, the carcinogenic risks of other fiber nanomaterials with morphological similarities to asbestos have not been fully studied. Ultra-long silver nanowires (AgNWs) are increasingly used fiber-shaped nanomaterials with a high aspect ratio, but very few studies have investigated their health risks. Here, proliferation abnormalities of lung epithelial cells induced by ultra-long AgNWs were investigated. Ultra-long AgNW treatment induced dose- and diameter-dependent increase in the ratio of multinucleated cells. Further, proteins involved in mitosis and cytokinesis, including Aurora A, p-Histone 3 (ser10), RhoA, p-MLC, and myosin IIb, were significantly upregulated after an ultra-long AgNW treatment, leading to mitotic abnormalities and cytokinetic failure. Meanwhile, exposure to ultra-long AgNWs induced cell cycle arrest. Interestingly, a series of experiments demonstrated that ROS generation and Ag+ release were not responsible for the multinucleation induced by ultra-long AgNWs, but ultra-long AgNWs in the intercellular bridge might obstruct the contractile ring and inhibit abscission of the cytokinetic furrow by direct physical contact. Altogether, our findings indicate that ultra-long AgNWs can induce chromosomal instability, which has important consequences for the safety of ultra-long AgNWs to human health.

Comparative toxicity of silver nanoparticles (AgNPs) and silver nanowires (AgNWs) on saltwater microcrustacean, Artemia salina.

This study evaluated the potential toxic effects of silver nanoparticles (AgNPs) and silver nanowires (AgNWs) on saltwater microcrustacean Artemia salina nauplii under ISO TS 20787 guideline. To investigate the acute toxicity of these nanomaterials, the nauplii were exposed to different concentrations of 0 (control), 0.39, 1.56, 6.25, 25 and 100 mg/L AgNPs and concentrations of 0 (control), 0.01, 0.1, 1, 10, 50 and 100 mg/L AgNWs for 72 h. Immobilization rate of A. salina exposed to both AgNPs and AgNWs for 72 h increased significantly in a concentration-dependent manner (P < 0.05). The 72 h EC10 and EC50 were found to be 1.48 ±â€¯0.6 and 10.70 ±â€¯1.3 mg/L for AgNPs, respectively, and 0.03 ±â€¯0.02 and 0.43 ±â€¯0.04 mg/L for AgNWs, respectively. Based on the EC10 and EC50 values, the toxicity of AgNWs was significantly higher than AgNPs (P < 0.05). Oxidative stress resulted from 48 h exposure to both AgNPs and AgNWs in A. salina was assessed by measuring reactive oxygen species (ROS) production and superoxide dismutase (SOD) activity. The results revealed that both AgNPs and AgNWs could induce ROS production. The SOD activity decreased significantly with the increase of exposure concentration (P < 0.05). In conclusion, the present results show that both nanomaterials have toxic effects on A. salina nauplii and thus, more effort should be made to prevent their release into saltwater ecosystems and trophic transfer in the aquatic food chain.

Systematic in vivo study of NiO nanowires and nanospheres: biodegradation, uptake and biological impacts.

High aspect ratio nanomaterials (NM) have a promising future in medicine and industry as a unique category of NM. Consequently, it is important to evaluate their potential biological side-effects before crediting their use. To understand the mechanisms of degradation, internalisation, and interaction with different biological targets, we used the in vivo model Drosophila melanogaster to obtain a systematic and complete study on high aspect ratio Ni nanowires (NiNW), compared with low aspect ratio Ni nanospheres (NiNS), and NiSO4 as a model of agent releasing nickel ions. The distinguished shape of nanowires showed changes in their characteristics after oral administration until they reached the intestinal lumen, where their diameter decreased significantly. For the first time, we confirmed the internalization of needle-shaped materials via perforation of the intestinal barrier. Moreover, the results showed that D. melanogaster is a valid and effective tool in studies related to magnetic resonance imaging (MRI). Additionally, NiNM induced DNA damage and molecular changes at the gene expression level, in association with increase in oxidative stress levels. Notably, the observed negative effects were related to nickel as a metal rather than to its shape, since the effects induced by the three Ni forms were notably similar. In addition, independent of their form, Ni compounds did not induce toxic or mutagenic impacts. Our Drosophila model can be used to understand different phenomena related to high aspect ratio NM exposure, such as degradation, internalization and interaction with different targets.

Effects of differently shaped TiO2NPs (nanospheres, nanorods and nanowires) on the in vitro model (Caco-2/HT29) of the intestinal barrier.

BACKGROUND: The biological effects of nanoparticles depend on several characteristics such as size and shape that must be taken into account in any type of assessment. The increased use of titanium dioxide nanoparticles (TiO2NPs) for industrial applications, and specifically as a food additive, demands a deep assessment of their potential risk for humans, including their abilities to cross biological barriers. METHODS: We have investigated the interaction of three differently shaped TiO2NPs (nanospheres, nanorods and nanowires) in an in vitro model of the intestinal barrier, where the coculture of Caco-2/HT29 cells confers inherent intestinal epithelium characteristics to the model (i.e. mucus secretion, brush border, tight junctions, etc.). RESULTS: Adverse effects in the intestinal epithelium were detected by studying the barrier's integrity (TEER), permeability (LY) and changes in the gene expression of selected specific markers. Using Laser Scanning Confocal Microscopy, we detected a different behaviour in the bio-adhesion and biodistribution of each of the TiO2NPs. Moreover, we were able to specifically localize each type of TiO2NPs inside the cells. Interestingly, general DNA damage, but not oxidative DNA damage effects, were detected by using the FPG version of the comet assay. CONCLUSIONS: Results indicate different interactions and cellular responses related to differently shaped TiO2NPs, nanowires showing the most harmful effects.

High-throughput tool to discriminate effects of NMs (Cu-NPs, Cu-nanowires, CuNO3, and Cu salt aged): transcriptomics in Enchytraeus crypticus.

The current testing of nanomaterials (NMs) via standard toxicity tests does not cover many of the NMs specificities. One of the recommendations lays on understanding the mechanisms of action, as these can help predicting long-term effects and safe-by-design production. In the present study, we used the high-throughput gene expression tool, developed for Enchytraeus crypticus (4 × 44k Agilent microarray), to study the effects of exposure to several copper (Cu) forms. The Cu treatments included two NMs (spherical and wires) and two copper-salt treatments (CuNO3 spiked and Cu salt field historical contamination). To relate gene expression with higher effect level, testing was done with reproduction effect concentrations (EC20, EC50), using 3 and 7 days as exposure periods. Results showed that time plays a major role in the transcriptomic response, most of it occurring after 3 days. Analysis of gene expression profiles showed that Cu-salt-aged and Cu-nanowires (Nwires) differed from CuNO3 and Cu-nanoparticles (NPs). Functional analysis revealed specific mechanisms: Cu-NPs uniquely affected senescence and cuticle pattern formation, which can result from the contact of the NPs with the worms' tegument. Cu-Nwires affected reproduction via male gamete generation and hermaphrodite genitalia development. CuNO3 affected neurotransmission and locomotory behavior, both of which can be related with avoidance response. Cu salt-aged uniquely affected phagocytosis and reproductive system development (via different mechanisms than Cu-Nwires). For the first time for Cu (nano)materials, the adverse outcome pathways (AOPs) drafted here provide an overview for common and unique effects per material and linkage with apical effects.

The Secretory Response of Rat Peritoneal Mast Cells on Exposure to Mineral Fibers.

BACKGROUND: Exposure to mineral fibers is of substantial relevance to human health. A key event in exposure is the interaction with inflammatory cells and the subsequent generation of pro-inflammatory factors. Mast cells (MCs) have been shown to interact with titanium oxide (TiO2) and asbestos fibers. In this study, we compared the response of rat peritoneal MCs challenged with the asbestos crocidolite and nanowires of TiO2 to that induced by wollastonite employed as a control fiber. METHODS: Rat peritoneal MCs (RPMCs), isolated from peritoneal lavage, were incubated in the presence of mineral fibers. The quantities of secreted enzymes were evaluated together with the activity of fiber-associated enzymes. The ultrastructural morphology of fiber-interacting RPMCs was analyzed with electron microscopy. RESULTS: Asbestos and TiO2 stimulate MC secretion. Secreted enzymes bind to fibers and exhibit higher activity. TiO2 and wollastonite bind and improve enzyme activity, but to a lesser degree than crocidolite. CONCLUSIONS: (1) Mineral fibers are able to stimulate the mast cell secretory process by both active (during membrane interaction) and/or passive (during membrane penetration) interaction; (2) fibers can be found to be associated with secreted enzymes-this process appears to create long-lasting pro-inflammatory environments and may represent the active contribution of MCs in maintaining the inflammatory process; (3) MCs and their enzymes should be considered as a therapeutic target in the pathogenesis of asbestos-induced lung inflammation; and (4) MCs can contribute to the inflammatory effect associated with selected engineered nanomaterials, such as TiO2 nanoparticles.

Dimension-dependent toxicity of silver nanomaterials on the cladocerans Daphnia magna and Daphnia galeata.

Silver nanomaterials (AgNMs) are widely used in many fields because of their antimicrobial properties. Depending on the shapes and dimensions of the AgNMs, their potential uses and needs vary. Consequently, vast quantities of multi-dimensional AgNMs are being manufactured and released into aquatic ecosystems, where they have toxic effects on aquatic organisms. Therefore, an assessment of the toxicities of each multi-dimensional AgNM on aquatic ecosystems is necessary. In this study, important aquatic model species, Daphnia magna and Daphnia galeata, were used to assess and compare the toxic effects of silver ions (Ag+ ions) and multi-dimensional AgNMs, including silver nanoparticles (AgNPs), silver nanowires (AgNWs), and silver nanoplates (AgPLs). The results indicated that Ag+ ions were more toxic than AgNMs of different dimensions and sizes, and that AgPLs were the most toxic of the AgNMs. In the case of AgNWs, the longer (20 µm) nanowire was more toxic than the shorter (10 µm) one. In addition, D. galeata was more sensitive than D. magna to both Ag+ ions and AgNMs. This study elucidates the dimension-dependent toxicity of and silver ions and nanomaterials in the cladocerans D. magna and D. galeata. Further studies will be necessary to further elucidate the actual risk of multi-dimensional nanomaterials in ecosystems.

Effects of silver nanowire length and exposure route on cytotoxicity to earthworms.

To accurately evaluate the environmental toxicity of silver nanowires (AgNWs), it is necessary to characterize how the cytotoxicity of these nanomaterials is affected by the route of exposure. However, few studies have addressed the exposure route or mechanism of toxicity of nanomaterials, particularly of nanowires, in living organisms. In this study, we therefore analyzed the main exposure route of AgNWs in vitro, using earthworms (Eisenia andrei) as a model system, via flow cytometry. We subsequently examined the in vivo toxicity of AgNWs to earthworms in soil. These tests revealed that intracellular esterase activity was correlated with adsorption of the nanowires to the surfaces of coelomocytes in vitro, and that in vivo cytotoxicity resulted mainly from oral, rather than dermal, exposure to the nanowires. Overall, shorter AgNWs (10 µm) were more toxic than longer AgNWs (20 µm). To our knowledge, this study is the first report regarding the ecotoxicity of nanowires to earthworms in soil. Our findings provide important information to help assess the risk of toxic AgNW contamination of soil ecosystems.