Effects of multi-walled carbon nanotube (MWCNT) on antioxidant depletion, the ERK signaling pathway, and copper bioavailability in the copepod (Tigriopus japonicus)

Proposing Effective Ecotoxicity Test Species for Chemical Safety Assessment in East Asia: A Review

East Asia leads the global chemical industry, but environmental chemical risk in these countries is an emerging concern. Despite this, only a few native species that are representative of East Asian environments are listed as test species in international guidelines compared with those native to Europe and America. This review suggests that Zacco platypus, Misgurnus anguillicaudatus, Hydrilla verticillata, Neocaridina denticulata spp., and Scenedesmus obliquus, all resident to East Asia, are promising test species for ecotoxicity tests. The utility of these five species in environmental risk assessment (ERA) varies depending on their individual traits and the state of ecotoxicity research, indicating a need for different applications of each species according to ERA objectives. Furthermore, the traits of these five species can complement each other when assessing chemical effects under diverse exposure scenarios, suggesting they can form a versatile battery for ERA. This review also analyzes recent trends in ecotoxicity studies and proposes emerging research issues, such as the application of alternative test methods, comparative studies using model species, the identification of specific markers for test species, and performance of toxicity tests under environmentally relevant conditions. The information provided on the utility of the five species and alternative issues in toxicity tests could assist in selecting test species suited to study objectives for more effective ERA.

Physiological effects and molecular response in the marine rotifer Brachionus plicatilis after combined exposure to nanoplastics and copper

Because nanoplastics (NPs) can transport pollutants, the absorption of surrounding pollutants into NPs and their effects are important environmental issues. This study shows a combined effect of high concentrations of NPs and copper (Cu) in the marine rotifer Brachionus plicatilis. Co-exposure decreased the growth rate, reproduction, and lifespan. The highest level of NP ingestion was detected in the co-treated group, but the Cu concentration was higher in the Cu single-exposure group. ERK activation played a key role in the downstream cell signaling pathway activated by the interaction of NPs and Cu. The increased sensitivity of B. plicatilis to Cu could be due to the impairment of MXR function caused by a high concentration of NPs, which supports our in vivo experiment results. Our results show that exposure to NPs could induce the dysfunction of several critical molecular responses, weakening resistance to Cu and thereby increasing its physiological toxicity in B. plicatilis.

Toxicity of amine-functionalized single-carbon nanotube (NH2 f-SWCNT) to Channel Catfish (Ietalurus Punetaus): Organ pathologies, oxidative stress, inflammation, and apoptosis

The rapid development of carbon nanotubes (CNTs) in the field of fish disease control and prevention raises concerns about the toxicity and safe use in fish. This study was performed to assess the effect on histological changes, oxidative stress related markers in response to various concentrations of amine-functionalized single carbon nanotubes (NH₂ f-SWCNT) (1, 10 and 100 mg kg^-1 fish) in Channel Catfish (Ietalurus Punetaus) for up to 10 days. Moreover, pro-inflammatory cytokine genes and apoptotic genes were analyzed to obtain a better understanding of molecular mechanism of NH₂ f-SWCNT induced toxicity. As a result, intraperitoneal (i.p.) administration of NH₂ f-SWCNT caused dose-dependent and time-dependent injuries in the sampled tissues. In comparison with the control groups, decrease of catalase (CAT) activity and superoxide dismutase (SOD), and increase of malondialdehyde (MDA) and lactin dehydrogenase (LDH) were observed in all treatments. Real-time PCR assay showed inflammatory response with dose-dependent increase of tumor necrosis factor alpha (TNFα) and transient increase of interleukin 1β (IL-1β) in the liver. NH₂ f-SWCNT administration induced increase of p38 as well as caspase-3 in all treatments compared to the control groups, indicating the involvement of p38-MAPK cascade and caspase-3 cascade in liver cell apoptosis. Overall, we conclude that NH₂ f-SWCNT exert effects by direct injury and indirectly oxidative stress, resulting in inflammation and apoptosis, which provides data for understanding of the biological mechanisms underlying the toxicity of CNTs in fish.

Glutathione S-Transferases in Marine Copepods

The glutathione S-transferase (GST) is a complex family of phase II detoxification enzymes, known for their ability to catalyze the conjugation of the reduced form of glutathione (GSH) to a wide variety of endogenous and exogenous electrophilic compounds for detoxification purposes. In marine environments, copepods are constantly exposed to multiple exogenous stressors, thus their capability of detoxification is key for survival. Full identification of the GST family in copepods has been limited only to few species. As for insects, the GST family includes a wide range of genes that, based on their cellular localization, can be divided in three classes: cytosolic, microsomal, and mitochondrial. The role of GSTs might have class-specific features, thus understanding the nature of the GST family has become crucial. This paper covers information of the GST activity in marine copepods based on studies investigating gene expression, protein content, and enzymatic activity. Using published literature and mining new publicly available transcriptomes, we characterized the multiplicity of the GST family in copepods from different orders and families, highlighting the possible role of these genes as biomarker for ocean health status monitoring.

Carbon Nanotubes Induce Metabolomic Profile Disturbances in Zebrafish: NMR-Based Metabolomics Platform

The present study aims to investigate the metabolic effects of single-walled carbon nanotubes (SWCNT) on zebrafish (Danio rerio) using ¹H nuclear magnetic resonance (¹H-NMR) spectroscopy. However, there is no significant information available regarding the characterization of organic molecules, and metabolites with SWCNT exposure. Noninvasive biofluid methods have improved our understanding of SWCNT metabolism in zebrafish in recent years. Here, we used targeted metabolomics to quantify a set of metabolites within biological systems. SWCNT at various concentrations was given to zebrafish, and the metabolites were extracted using two immiscible solvent systems, methanol and chloroform. Metabolomics profiling was used in association with univariate and multivariate data analysis to determine metabolomic phenotyping. The metabolites, malate, oxalacetate, phenylaniline, taurine, sn-glycero-3-phosphate, glycine, N-acetyl mate, lactate, ATP, AMP, valine, pyruvate, ADP, serine, niacinamide are significantly impacted. The metabolism of amino acids, energy and nucleotides are influenced by SWCNT which might indicate a disturbance in metabolic reaction networks. In conclusion, using high-throughput analytical methods, we provide a perspective of metabolic impacts and the underlying associated metabolic pathways.

Multi-Walled Carbon Nanotubes (MWCNTs) Cause Cellular Senescence in TGF-β Stimulated Lung Epithelial Cells

Multi-walled carbon nanotubes are engineered nanomaterials (ENMs) that have a fiber-like structure which may be a concern for the development of cellular senescence. Premature senescence, a state of irreversible cell cycle arrest, is implicated in the pathogenesis of chronic lung diseases such as pulmonary fibrosis (PF). However, the crosstalk between downstream pathways mediating fibrotic and senescent responses of MWCNTs is not well-defined. Here, we exposed human bronchial epithelial cells (BEAS-2B) to MWCNTs for up to 72 h and demonstrate that MWCNTs increase reactive oxygen species (ROS) production accompanied by inhibition of cell proliferation. In addition, MWCNT exposure resulted in the increase of p21 protein abundance and senescence associated β-galactosidase (SA β-gal) activity. We also determined that co-exposure with the cytokine, transforming growth factor-β (TGF-β) exacerbated cellular senescence indicated by increased protein levels of p21, p16, and γH2A.X. Furthermore, the production of fibronectin and plasminogen activator inhibitor (PAI-1) was significantly elevated with the co-exposure compared to MWCNT or TGF-β alone. Together, our study suggests that the cellular senescence potential of MWCNTs may be enhanced by pro-fibrotic mediators, such as TGF-β in the surrounding microenvironment.

Evaluation of hesperetin-loaded on multiple wall carbon nanotubes on cerebral ischemia/reperfusion injury in rats

The present study aimed to develop novel hesperetin-loaded on multiple wall carbon nanotubes (Hst-MWCNTs) to resolve the restricted bioavailability of hesperetin (Hst) and to enhance its preventive effect on cerebral ischemia-reperfusion (I/R). The physicochemical characteristics of Hst-MWCNTs were evaluated by Fourier-transform infrared spectra (FT-IR) and field emission scanning electron microscopy (FE-SEM). Forty male Wistar rats were randomly divided into five groups (control, I/R, MWCNTs, Hst, and Hst-MWCNTs). Hst, MWCNTs and Hst-MWCNTs (15 mg/kg orally) were pretreated for 14 days, and then I/R was induced by bilateral common carotid artery occlusion (BCCAO). Learning and memory deficits were evaluated using the novel object recognition test (NORT). The percentage of infarct size, catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GRx), glutathione peroxidase (GPx) activities, malondialdehyde (MDA), and glutathione (GSH) levels was evaluated. Caspase-3 and Bcl-2 expressions were detected by qRT-PCR and Western blot analysis. Compared to the I/R group, Hst-MWCNTs considerably reduced learning and memory deficits, infarct size, and MDA levels. CAT, SOD, GRx, GPx activities and GSH levels were significantly increased in the Hst-MWCNTs group than in the I/R group. Additionally, Hst-MWCNTs significantly reduced the Caspase-3 expression but increased the Bcl-2 expression. All these results indicated that MWCNTs could be used as a promising novel carrier to enhance the oral bioavailability of Hst and to treat cerebral I/R injury.

Influence of multi-walled carbon nanotubes on enantioselective bioaccumulation and oxidative stress toxicity of indoxacarb in zebrafish(Danio rerio)

Carbon nanotubes (CNTs) have been widely used in various fields with the rapid development of nanotechnology. Pesticides have an irreplaceable role in agricultural production, which leads to their massive utilization and their inevitably penetrate into the aquatic environment. However, limited information is available regarding the impact of CNTs on the toxicity and enrichment of chiral compounds to organisms. Using zebrafish as a model to study whether the enantioselective bioaccumulation and oxidative stress of chiral pollutants may be altered in the presence of MWCNTs. Significant enantioselective bioaccumulation was observed in zebrafish with the preferential accumulation of R-(-)-indoxacarb during the 28-day bioaccumulation. The combined exposure of MWCNTs does not affect the enantioselectivity of zebrafish bioaccumulation, but increase the bioaccumulation amount of R-(-)-indoxacarb by 65%. Moreover, the average degradation half-life of indoxacarb enantiomers was 1.30 days. The indoxacarb causes oxidative stress toxicity in zebrafish liver and exhibited enantioselectivity, while the addition of MWCNTs did not significantly change the enantioselectivity of oxidative stress toxicity of indoxacarb, but enhanced the toxicity 20% with increased MWCNTs concentrations. This study suggests that the risk of the co-presence of nanomaterials and chiral pesticides in aquatic environments should be taken into consideration.

Effects of multi-walled carbon nanotubes on the enantioselective toxicity of the chiral insecticide indoxacarb toward zebrafish (Danio rerio)

The mass production and usage of carbon nanotubes (CNTs) have led to the inevitable release into the environment, and the effects of CNTs on the toxicity of co-existing pollutants have been well documented. However, knowledge of the effects of CNTs on the enantioselective toxicity of chiral compounds is limited. Using zebrafish as an experimental model, the enantioselective expression of the apoptosis, CYP3C and EAAT-related genes were analyzed following exposure to multi-walled carbon nanotubes (MWCNTs) (0.05 and 0.5 mg/L), rac-/R-/S-indoxacarb (0.01 mg/L), or the combination of rac-/R-/S-indoxacarb mixed with MWCNTs for 28d. Sex-specific differences were observed in both the liver and brain of zebrafish. The expression of apoptosis and CYP3C-related genes was 16.55-44.29 times higher in the livers of males treated with R-indoxacarb than in S-indoxacarb treated groups. The EAAT-related genes were expressed at 1.38-2.56 times higher levels in the brain of females treated with R-indoxacarb than in S-indoxacarb-treated groups. In the presence of MWCNTs, the expression of caspase-3, cyp3c3, cyp3c4, eaat1a, eaat1b and eaat2 in the livers of males and brains of females treated with S-indoxacarb were 1.65-15.33 times higher than in fish treated with R-indoxacarb. Based on these results, MWCNTs affected the enantioselective toxicity of indoxacarb toward zebrafish.

Effects of multiwalled carbon nanotubes co-exposure with cadmium on zebrafish cell line: Metal uptake and accumulation, oxidative stress, genotoxicity and cell cycle

Carbon nanotubes presence in the environment increases every year because of exponential industrial production around the world. In aquatic environments, carbon nanotubes can interact with other pollutants based on their adsorbent surface chemistry properties. Heavy metal ions represent one of the biggest concerns in water resources nowadays due to anthropogenic activities, in which cadmium (Cd) is one of the most harmful metal for aquatic organisms. This study investigated the influence of two co-exposure protocols differing by the order of interaction of oxidized multiwalled carbon nanotubes (ox-MWCNT) with Cd in zebrafish liver cell line (ZFL). The ox-MWCNT was characterized, Cd content in culture medium and uptake by cells were quantified using ICP-MS and, the reactive oxygen species (ROS), the biotransformation enzymes activity of phase I and II as well as the antioxidants defenses and oxidative damage were analyzed. The effects on the cell cycle were investigated by flow cytometry and DNA damage by comet assay. The exposure to ox-MWCNT alone decreased the activity of catalase, glutathione peroxidase, and glutathione S-transferase and altered the cell cycle with a reduction of cells in the G2/M phase. Cd exposure alone decreased the activity of catalase and glutathione S-transferase, increased ROS, metallothionein, and lipid peroxidation content and causes genotoxicity in the cells. Despite different incubation protocol, the co-exposure ox-MWCNT-Cd increased the Cd content in ZFL cells after 24 h exposure, increased ROS production and DNA damage without differences between them. Our results showed the modulation of ox-MWCNT on Cd effects and contributed to future co-exposure toxicity investigations and nanosafety regulations involving carbon nanomaterials and aquatic pollutants.

The glutathione S-transferase genes in marine rotifers and copepods: Identification of GSTs and applications for ecotoxicological studies

Various xenobiotics are constantly being released and accumulated into the aquatic environments and consequently, the aquatic organisms are continuously being exposed to exogenous stressors. Among various xenobiotic detoxifying enzymes, Glutathione S-transferase (GST) is one of the major xenobiotic detoxifying enzyme which is widely distributed among living organisms and thus, understanding of the nature of GSTs is crucial. Previous studies have shown GST activity in response to various xenobiotics yet, full identification of GSTs in marine invertebrates is still limited. This review covers information on the importance of GSTs as a biomarker for emerging chemicals and their response to wide ranges of environmental pollutants as well as in-depth phylogenetic analysis of marine invertebrates, including recently identified GSTs belonging to rotifers (Brachionus spp.) and copepods (Tigriopus japonicus and Paracyclopina nana), with unique class-specific features of GSTs, as well as a new suggestion of GST evolutionary pathway.

Polystyrene nanoplastic induces ROS production and affects the MAPK-HIF-1/NFkB-mediated antioxidant system in Daphnia pulex

Recently, research on the biological effects of nanoplastics has grown exponentially. However, studies on the effects of nanoplastics on freshwater organisms and the mechanisms of the biological effects of nanoplastics are limited. In this study, the content of reactive oxygen species (ROS), gene and protein expression in the MAPK-HIF-1/NFkB pathway, and antioxidant gene expressions and enzyme activities were measured in Daphnia pulex exposed to polystyrene nanoplastic. In addition, the full-length extracellular signal-regulated kinases (ERK) gene, which plays an important role in the MAPK pathway, was cloned in D. pulex, and the amino acid sequence, function domain, and phylogenetic tree were analyzed. The results show that nanoplastic caused the overproduction of ROS along with other dose-dependent effects. Low nanoplastic concentrations (0.1 and/or 0.5 mg/L) significantly increased the expressions of genes of the MAPK pathway (ERK; p38 mitogen-activated protein kinases, p38; c-Jun amino-terminal kinases, JNK; and protein kinase B, AKT), HIF-1 pathway (prolyl hydroxylasedomain, PHD; vascular endothelial growth factor, VEGF; glucose transporter, GLUT; pyruvate kinase M, PKM; hypoxia-inducible factor 1, HIF1), and CuZn superoxide dismutase (SOD) along with the activity of glutathione-S-transferase. As the nanoplastic concentration increased, these indicators were significantly suppressed. The protein expression ratio of ERK, JNK, AKT, HIF1α, and NFkBp65 (nuclear transcription factor-kB p65) as well as the phosphorylation of ERK and NFkBp65 were increased in a dose-dependent manner. The activities of other antioxidant enzymes (catalase, total SOD, and CuZn SOD) were significantly decreased upon exposure to nanoplastic. Combined with our previous work, these results suggest that polystyrene nanoplastic causes the overproduction of ROS and activates the downstream pathway, resulting in inhibited growth, development, and reproduction. The present study fosters a better understanding of the biological effects of nanoplastics on zooplankton.

Investigating the toxicities of different functionalized polystyrene nanoplastics on Daphnia magna

Nanoplastics (NPs) spread widely with water and air current, and they can accumulate in aquatic organisms, even penetrating biofilms, which may cause persistent toxicity and potential hazards. This current study aimed to reveal the toxicological mechanism of different functionalized polystyrene (PS) NPs on Daphnia magna (D. magna) by investigating toxicity endpoints in individual level and biochemical level. In this study, acute toxicity, behavioral parameters and biomarker responses of D. magna was measured in the exposure of different functionalized PS NPs (plain PS, PS-p-NH₂, PS-n-NH₂ and PS-COOH). The results indicated that when exposed to the plain PS, ROS induction would activate MAPKs, thereby causing lethality and adverse behavior effects on D. magna; while the functionalized PS NPs were less toxic than the plain PS, especially for PS-p-NH₂ which was severely flocculated after exposure, thus showing no immobilization at the investigated concentrations. Also, the antioxidant system was mainly stimulated due to the direct interaction with the cell surface receptor, which was different from the plain PS. Consequently, this work suggests significant effects of functional groups on NPs for environmental toxicity studies, and provides a better understanding of the toxicological mechanism on the toxicity of PS NPs toward D. magna.

n-Butyl acrylate-induced antioxidant system alteration through two generations in Oryzias latipes

n-Butyl acrylate (nBA) is one of acrylate esters which has been applied to diverse industrial fields. For unveiling of xeno-estrogenic effects and oxidative stress induction by nBA under two-generational exposure regimen (17 weeks), the biomarkers relevant to an estrogenic effect and oxidative stress were analyzed. Acute toxicity value of nBA in Oryzias latipes was 7.2 mg/L (96 h-LC50). Over exposure time, the significant transcriptional change of cytochrome P450 19A (CYP19A) and vitellogenin 1/2 (VTG1/2) was not observed (one-way ANOVA, P < 0.05), meaning no estrogenic effect of nBA. Significant reduction of glutathione (GSH) content was observed in F0 male and female fish, while in F1 male, the content was increased (P < 0.05). Catalase (CAT) activity of male fish showed the significant decrease in both F0 and F1 fish, showing multi-generational suppressing effect of nBA on CAT activity. But in case of reactive oxygen species (ROS), expression level and glutathione S-transferase (GST) activity were not modulated in response to nBA. These findings suggest that nBA could affect an antioxidant system alteration through GSH depletion and inhibition of CAT activity which could be transferred to the next generation, whereas xeno-estrogenic effect would be questionable.

Effect of Multi-walled Carbon Nanotubes on the Toxicity of Triphenyltin to the Marine Copepod Tigriopus japonicus

Marine organisms are often exposed to a mixture of various pollutants in marine environment (i.e., nanoparticles, organic pollutants). The present study investigated the potential effects of multi-walled carbon nanotubes (MWCNTs) on the toxicity of triphenyltin chloride (TPTCl). The results revealed an antagonistic interaction between MWCNTs and TPTCl on the copepod through 96 h acute exposure, which was attributed to the adsorption of TPTCl to MWCNTs and aggregation of MWCNTs in the test solutions. Results of 21 days' chronic exposure showed that the effect concentration of MWCNTs could be 100 times lower than that of acute exposure. The exposure to binary mixture of MWCNT (1.0 mg/L) and TPTCl (0.3 µg/L) caused a reduction by 94% for the 3rd time spawning and 83% for the total number of hatched nauplii. The ingestion and exterior attachment of MWCNTs to the copepod might be the main reasons causing the adverse effect in reproduction.

Adverse effects, expression of defense-related genes, and oxidative stress-induced MAPK pathway in the benzo[α]pyrene-exposed rotifer Brachionus rotundiformis

To examine the adverse effects of the benzo[α]pyrene (B[α]P), the monogonont rotifer Brachionus rotundiformis was exposed to various concentration of B[α]P (0 [control], 1, 10, and 100 μg/L) and measured life cycle parameters (e.g., mortality, fecundity [cumulated number of offspring], and lifespan), reactive oxygen species (ROS), antioxidant enzymatic activity of glutathione S-transferase (GST). In addition, defense-related transcripts (e.g., glutathione S-transferases [GSTs], ATP binding cassette [ABCs] transporters) and Western blot analysis of mitogen-activated protein kinase (MAPK) signaling pathway were investigated in B[α]P-exposed rotifer. In this study, the total intracellular ROS level and GST activity were significantly increased (P < 0.05), while fecundity and lifespan were also significantly (P < 0.05) reduced in a concentration dependent manner in B[α]P-exposed B. rotundiformis. In addition, transcriptional regulation of GSTs and ABC transporters were significantly upregulated and downregulated (P < 0.05), respectively, suggesting that B[α]P can induce oxidative stress leading to induction of antioxidant system and detoxification mechanism. In addition to detoxification-related genes, B[α]P-exposed B. rotundiformis showed the increased levels of the p-JNK and p-p38, suggesting that B[α]P can activate MAPK signaling pathway in B. rotundiformis.

Environmental mixtures of nanomaterials and chemicals: The Trojan-horse phenomenon and its relevance for ecotoxicity

The usage of engineered nanomaterials (NM) offers many novel products and applications with advanced features, but at the same time raises concerns with regard to potential adverse biological effects. Upon release and emission, NM may interact with chemicals in the environment, potentially leading to a co-exposure of organisms and the occurrence of mixture effects. A prominent idea is that NM may act as carriers of chemicals, facilitating and enhancing the entry of substances into cells or organisms, subsequently leading to an increased toxicity. In the literature, the term 'Trojan-horse effect' describes this hypothesis. The relevance of this mechanism for organisms is, however, unclear as yet. Here, a review has been performed to provide a more systematic picture on existing evidence. It includes 151 experimental studies investigating the exposure of various NM and chemical mixtures in ecotoxicological in vitro and in vivo model systems. The papers retrieved comprised studies investigating (i) uptake, (ii) toxicity and (iii) investigations considering both, changes in substance uptake and toxicity upon joint exposure of a chemical with an NM. A closer inspection of the studies demonstrated that the existing evidence for interference of NM-chemical mixture exposure with uptake and toxicity points into different directions compared to the original Trojan-horse hypothesis. We could discriminate at least 7 different categories to capture the evidence ranging from no changes in uptake and toxicity to an increase in uptake and toxicity upon mixture exposure. Concluding recommendations for the consideration of relevant processes are given, including a proposal for a nomenclature to describe NM-chemical mixture interactions in consistent terms.

Cross-reactivities of mammalian MAPKs antibodies in rotifer and copepod: Application in mechanistic studies in aquatic ecotoxicology

The mitogen-activated protein kinases (MAPKs) family is known to mediate various biological processes in response to diverse environmental pollutants. Although MAPKs are well characterized and studied in vertebrates, in invertebrates the cross-reactivities of MAPKs antibodies were not clearly known in response to environmental pollutants due to limited information of antibody epitopes with material resources for invertebrates. In this paper, we performed phylogenetic analysis of MAPKs genes in the marine rotifer Brachionus koreanus and the copepods Paracyclopina nana and Tigriopus japonicus. Also in rotifer and copepods, several studies of Western blot of MAPK signaling pathways were shown in response to environmental pollutants, including multi-walled carbon nanotubes (MWCNTs), water-accommodated fractions (WAFs) of crude oil, and microplastics. This paper will provide a better understanding of the underlying mechanistic scenario in terms of cross-reactivities of mammalian antibodies in rotifer and copepod.

Antioxidant nanomaterials in advanced diagnoses and treatments of ischemia reperfusion injuries

Organ ischemia with inadequate oxygen supply followed by reperfusion (which initiates a complex of inflammatory responses and oxidative stress) occurs in different clinical conditions and surgical procedures including stroke, myocardial infarction, limb ischemia, renal failure, organ transplantation, free-tissue-transfer, cardiopulmonary bypass, and vascular surgery. Even though pharmacological treatments protect against experimental ischemia reperfusion (I/R) injury, there has not been enough success in their application for patient benefits. The main hurdles in the treatment of I/R injury are the lack of diagnosis tools for understanding the complicated chains of I/R-induced signaling events, especially in the acute phase after ischemia, determining the affected regions of the tissue over time, and then, targeting and safe delivery of antioxidants, drugs, peptides, genes and cells to the areas requiring treatment. Besides the innate antioxidant and free radical scavenging properties, some nanoparticles also show higher flexibility in drug delivery and imaging. This review highlights three main approaches in nanoparticle-mediated targeting of I/R injury: nanoparticles (1) as antioxidants for reducing tissue oxidative stress, (2) for targeted delivery of therapeutic agents to the ischemic regions or cells, and (3) for imaging I/R injury at the molecular, cellular or tissue level and monitoring its evolution using contrasts induced by nanoparticles. These approaches can also be combined to realize so called theranostics for providing simultaneous diagnosis of ischemic regions and treatments by targeted delivery.

Length, but Not Reactive Edges, of Cup-stack MWCNT Is Responsible for Toxicity and Acute Lung Inflammation

Multiwalled carbon nanotube (MWCNT) toxicity after inhalation has been associated with size, aspect ratio, rigidity, surface modification, and reactive oxygen species production. In this study, we investigated a series of cup-stacked MWCNT prepared as variants of the Creos 24PS. Mechanical chopping produced a short version (AR10) and graphitization to remove active reaction sites by extreme heat (2,800°C; Creos 24HT) to test the contribution of length and alteration of potential reaction sites to toxicity. The 3 MWCNT variants were tested in vitro in a human macrophage-like cell model and with C57BL/6 alveolar macrophages for dose-dependent toxicity and NLRP3 inflammasome activation. The 24PS and 24HT variants showed significant dose-dependent toxicity and inflammasome activation. In contrast, the AR10 variant showed no toxicity or bioactivity at any concentration tested. The in vivo results reflected those observed in vitro, with the 24PS and 24HT variants resulting in acute inflammation, including elevated polymorphonuclear counts, Interleukin (IL)-18, cathepsin B, and lactate dehydrogenase in isolated lung lavage fluid from mice exposed to 40 µg MWCNT. Taken together, these data indicate that length, but not the absence of proposed reaction sites, on the MWCNT influences particle bioactivity.

Evaluation of Complex Toxicity of Canbon Nanotubes and Sodium Pentachlorophenol Based on Earthworm Coelomocytes Test

As a standard testing organism in soil ecosystems, the earthworm Eisenia fetida has been used widely in toxicity studies. However, tests at the individual level are time- and animal-consuming, with limited sensitivity. Earthworm coelomocytes are important for the assimilation and elimination of exogenous compounds and play a key role in the processes of phagocytosis and inflammation. In this study, we explored an optimal condition to culture coelomocytes of E. fetida in vitro and investigated the cytotoxicity of multiwalled carbon nanotubes (MWCNTs) and sodium pentachlorophenol (PCP-Na) using coelomocytes via evaluating lethal toxicity, oxidative stress, membrane damage, and DNA damage. The results showed that coelomocytes can be successfully cultured in vitro in primary under the RPMI-1640 medium with 2-4×104 cells/well (1-2×105 cells/mL) in 96-well plates at 25°C without CO2. Both MWCNTs and PCP-Na could cause oxidative damage and produce ROS, an evidence for lipid peroxidation with MDA generation and SOD and CAT activity inhibition at high stress. The two chemicals could separately damage the cell membrane structure, increasing permeability and inhibiting mitochondrial membrane potential (MMP). In addition, our results indicate that PCP-Na may be adsorbed onto MWCNTs and its toxicity on earthworm was accordingly alleviated, while a synergetic effect was revealed when PCP-Na and MWCNTs were added separately. In summary, coelomocyte toxicity in in vitro analysis is a sensitive method for detecting the adverse effects of carbon nanotubes combined with various pollutants.

Evaluation of Complex Toxicity of Canbon Nanotubes and Sodium Pentachlorophenol Based on Earthworm Coelomocytes Test

As a standard testing organism in soil ecosystems, the earthworm Eisenia fetida has been used widely in toxicity studies. However, tests at the individual level are time- and animal-consuming, with limited sensitivity. Earthworm coelomocytes are important for the assimilation and elimination of exogenous compounds and play a key role in the processes of phagocytosis and inflammation. In this study, we explored an optimal condition to culture coelomocytes of E. fetida in vitro and investigated the cytotoxicity of multiwalled carbon nanotubes (MWCNTs) and sodium pentachlorophenol (PCP-Na) using coelomocytes via evaluating lethal toxicity, oxidative stress, membrane damage, and DNA damage. The results showed that coelomocytes can be successfully cultured in vitro in primary under the RPMI-1640 medium with 2–4×10⁴ cells/well (1–2×10⁵ cells/mL) in 96-well plates at 25°C without CO₂. Both MWCNTs and PCP-Na could cause oxidative damage and produce ROS, an evidence for lipid peroxidation with MDA generation and SOD and CAT activity inhibition at high stress. The two chemicals could separately damage the cell membrane structure, increasing permeability and inhibiting mitochondrial membrane potential (MMP). In addition, our results indicate that PCP-Na may be adsorbed onto MWCNTs and its toxicity on earthworm was accordingly alleviated, while a synergetic effect was revealed when PCP-Na and MWCNTs were added separately. In summary, coelomocyte toxicity in in vitro analysis is a sensitive method for detecting the adverse effects of carbon nanotubes combined with various pollutants.

BDE-47 induces oxidative stress, activates MAPK signaling pathway, and elevates de novo lipogenesis in the copepod Paracyclopina nana

Brominated flame retardant, 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47), has received grave concerns as a persistent organic pollutant, which is toxic to marine organisms, and a suspected link to endocrine abnormalities. Despite the wide distribution in the marine ecosystem, very little is known about the toxic impairments on marine organisms, particularly on invertebrates. Thus, we examined the adverse effects of BDE-47 on life history trait (development), oxidative markers, fatty acid composition, and lipid accumulation in response to BDE-47-induced stress in the marine copepod Paracyclopina nana. Also, activation level of mitogen-activated protein kinase (MAPK) signaling pathways along with the gene expression profile of de novo lipogenesis (DNL) pathways were addressed. As a result, BDE-47 induced oxidative stress (e.g. reactive oxygen species, ROS) mediated activation of extracellular signal-regulated kinase (ERK) and c-Jun-N-terminal kinase (JNK) signaling cascades in MAPK pathways. Activated MAPK pathways, in turn, induced signal molecules that bind to the transcription factors (TFs) responsible for lipogenesis to EcR, SREBP, ChREBP promoters. Also, the stress stimulated the conversion of saturated fatty acids (SFAs) to polyunsaturated fatty acids (PUFAs), a preparedness of the organism to adapt the observed stress, which could be correlated with the elongase and desaturase gene (e.g. ELO3, Δ5-DES, Δ9-DES) expressions, and then extended to the delayed early post-embryonic development and increased accumulation of lipid droplets in P. nana. This study will provide a better understanding of how BDE-47 effects on marine invertebrates particularly on the copepods, an important link in the marine food chain.

Adverse effects of MWCNTs on life parameters, antioxidant systems, and activation of MAPK signaling pathways in the copepod Paracyclopina nana

Engineered multi-walled carbon nanotubes (MWCNTs) have received widespread applications in a broad variety of commercial products due to low production cost. Despite their significant commercial applications, CNTs are being discharged to aquatic ecosystem, leading a threat to aquatic life. Thus, we investigated the adverse effect of CNTs on the marine copepod Paracyclopina nana. Additional to the study on the uptake of CNTs and acute toxicity, adverse effects on life parameters (e.g. growth, fecundity, and size) were analyzed in response to various concentrations of CNTs. Also, as a measurement of cellular damage, oxidative stress-related markers were examined in a time-dependent manner. Moreover, activation of redox-sensitive mitogen-activated protein kinase (MAPK) signaling pathways along with the phosphorylation pattern of extracellular signal-regulated kinase (ERK), p38, and c-Jun-N-terminal kinases (JNK) were analyzed to obtain a better understanding of molecular mechanism of oxidative stress-induced toxicity in the copepod P. nana. As a result, significant inhibition on life parameters and evoked antioxidant systems were observed without ROS induction. In addition, CNTs activated MAPK signaling pathway via ERK, suggesting that phosphorylated ERK (p-ERK)-mediated adverse effects are the primary cause of in vitro and in vivo endpoints in response to CNTs exposure. Moreover, ROS-independent activation of MAPK signaling pathway was observed. These findings will provide a better understanding of the mode of action of CNTs on the copepod P. nana at cellular and molecular level and insight on possible ecotoxicological implications in the marine environment.

Multi-walled carbon nanotubes (MWCNTs) lead to growth retardation, antioxidant depletion, and activation of the ERK signaling pathway but decrease copper bioavailability in the monogonont rotifer (Brachionus koreanus)

To examine the toxic effects of multi-walled carbon nanotubes (MWCNTs) in the marine environment, we first exposed the monogonont rotifer (Brachionus koreanus) to MWCNTs in the presence of copper. The acute toxicity of copper decreased significantly with a decrease in copper bioavailability resulting from MWCNT exposure. Furthermore, we examined the effects of MWCNT exposure on reproductive capacity, population growth rate, growth patterns, antioxidant systems, and mitogen-activated protein kinase (MAPK) activation. Reproductive capacity, population growth rate, and body growth rate were significantly suppressed in B. koreanus in response to 1.3-4mg/L MWCNT exposure. Furthermore, MWCNTs induced the generation of reactive oxygen species (ROS) and decreased the antioxidant enzymatic activities of catalase (CAT) and glutathione reductase (GR). However, the enzymatic activity of glutathione S-transferase (GST) was up-regulated after a 24 h-exposure to 100mg/L MWCNTs. Exposure to 100mg/L MCWNTs induced extracellular signal-regulated kinase (ERK) activation in B. koreanus, suggesting that p-ERK may mediate the adverse effects of MWCNTs in B. koreanus via the MAPK signaling pathway. Our results provide insight into the mechanistic basis of the ecotoxicological effects of MWCNTs in the marine environment.