Effects of multiwalled carbon nanotubes and triclocarban on several eukaryotic cell lines: elucidating cytotoxicity, endocrine disruption, and reactive oxygen species generation

Involvement of ahr-dependent Cyp1a detoxification activity, oxidative stress and inflammatory regulation in response to graphene oxide exposure in rainbow trout (Oncorhynchus mykiss)

Graphene oxide (GO) is a very attractive material for use in a vast number of applications. However, before its widespread use, it is important to consider potential issues related to environmental safety to support its safe application. The aim of this study was to investigate effects on fish (rainbow trout) following GO exposure. Using both an in vitro approach with the RTL W1 rainbow trout liver cell line, and in vivo exposures, following OECD TG 203, disturbances at the cellular level as well as in the gills and liver tissue of juvenile trout were assessed. In RTL W1 cells, a time and concentration-dependent loss in cell viability, specifically plasma membrane integrity and lysosomal function, was observed after 96 h of exposure to GO at concentrations ≥18.75 mg/L. Additionally, increased reactive oxygen species (ROS) levels were evidenced at concentrations ≥18.75 mg/L, and an enhancement of metabolic activity was noted with concentrations ≥4.68 mg/L. In vivo exposures to GO did not provoke mortality in rainbow trout juveniles following 96 h exposure but led to histological alterations in gills and liver tissues, induction of enzymatic detoxification activities in the liver, as well as aryl hydrocarbon receptor (ahr)-cytochrome P450 1a (cyp1a) gene expression downregulation, and upregulation of pro-inflammatory cytokines il1b and il8 at GO concentrations ≥9.89 mg/L.

Unveiling combined ecotoxicity: Interactions and impacts of engineered nanoparticles and PPCPs

Emerging contaminants such as engineered nanoparticles (ENPs), pharmaceuticals and personal care products (PPCPs) are of great concern because of their wide distribution and incomplete removal in conventional wastewater and soil treatment processes. The production and usage of ENPs and PPCPs inevitably result in their coexistence in different environmental media, thus posing various risks to organisms in aquatic and terrestrial ecosystems. However, the existing literature on the physicochemical interactions between ENPs and PPCPs and their effects on organisms is rather limited. Therefore, this paper summarized the ecotoxicity of combined ENPs and PPCPs by discussing: (1) the interactions between ENPs and PPCPs, including processes such as aggregation, adsorption, transformation, and desorption, considering the influence of environmental factors like pH, ionic strength, dissolved organic matter, and temperature; (2) the effects of these interactions on bioaccumulation, bioavailability and biotoxicity in organisms at different trophic levels; (3) the impacted of ENPs and PPCPs on cellular-level biological process. This review elucidated the potential ecological hazards associated with the interaction of ENPs and PPCPs, and serves as a foundation for future investigations into the ecotoxicity and mode of action of ENPs, PPCPs, and their co-occurring metabolites.

Long-Term Triclocarban Exposure Induced Enterotoxicity by Triggering Intestinal AhR-Mediated Inflammation and Disrupting Microbial Community in Mice

Exposure to triclocarban (TCC), a commonly used antibacterial agent, has been shown to induce significant intestine injuries and colonic inflammation in mice. However, the detailed mechanisms by which TCC exposure triggered enterotoxicity remain largely unclear. Herein, intestinal toxicity effects of long-term and chronic TCC exposure were investigated using a combination of histopathological assessments, metagenomics, targeted metabolomics, and biological assays. Mechanically, TCC exposure caused induction of intestinal aryl hydrocarbon receptor (AhR) and its transcriptional target cytochrome P4501A1 (Cyp1a1) leading to dysfunction of the gut barrier and disruption of the gut microbial community. A large number of lipopolysaccharides (LPS) are released from the gut lumen into blood circulation owing to the markedly increased permeability and gut leakage. Consequently, toll-like receptor-4 (TLR4) and NF-κB signaling pathways were activated by high levels of LPS. Simultaneously, classic macrophage phenotypes were switched by TCC, shown with marked upregulation of macrophage M1 and downregulation of macrophage M2 that was accompanied by striking upregulation of proinflammatory factors such as Il-1β, Il-6, Il-17, and Tnf-α in the intestinal lamina propria. These findings provide new evidence for the TCC-induced enterotoxicity.

An informative short-term study on the impacts of a triclocarban/weathered multi-walled carbon nanotube-adsorbed complex to benthic organisms

Freshwater organisms are suitable models to study the fate of environmental pollutants. Due to their versatile and everyday use, many environmental pollutants such as triclocarban (TCC) or multi-walled carbon nanotubes (MWCNTs) enter environmental compartments very easily. TCC is known as a disinfectant and is declared as a highly aquatic toxicant. Multi-walled carbon nanotubes are used, e.g., in the automotive industry to improve plastic properties. Both TCCs and MWCNTs can pose major pollution hazards to various organisms. In addition, these substances can bind to each other due to their tendency to interact via strong hydrophobic interactions. Therefore, a short-term test was conducted to investigate the effects of the individual chemicals TCC and weathered MWCNTs (wMWCNTs) on a benthic biofilm and a grazing organism, Lymnaea stagnalis. Furthermore, the two compounds were coupled by an adsorption experiment resulting in a coupled complex formation (TCC + wMWCNTs). L. stagnalis showed no effects in terms of mortality. For benthic biofilm, the coupling test (TCC + wMWCNTs) showed a decrease of 58% in chlorophyll a (Chl-a) concentration. The main effect could be attributed to the wMWCNTs' exposure alone (decrease of 82%), but not to presence of TCC. The concentration range of Chl-a upon TCC exposure alone was comparable to that in the control group (32 and 37 µg/cm2). With respect to the particulate organic carbon (POC) concentration, very similar results were found for the solvent control, the TCC, and also for the TCC + wMWCNTs group (3, 2.9, and 2.9 mg/cm2). In contrast to the control, a significant increase in POC concentration (100%) was observed for wMWCNTs, but no synergistic effect of TCC + wMWCNTs was detected.

The Potentiating Effect of Graphene Oxide on the Arylhydrocarbon Receptor (AhR)-Cytochrome P4501A (Cyp1A) System Activated by Benzo(k)fluoranthene (BkF) in Rainbow Trout Cell Line

The increasing use of graphene oxide (GO) will result in its release into the environment; therefore, it is essential to determine its final fate and possible metabolism by organisms. The objective of this study was to assess the possible role of the aryl hydrocarbon receptor (AhR)-dependent cytochrome P4501A (Cyp1A) detoxification activities on the catabolism of GO. Our hypothesis is that GO cannot initially interact with the AhR, but that after an initial degradation caused by other mechanisms, small fractions of GO could activate the AhR, inducing Cyp1A. The environmental pollutant benzo(k)fluoranthene (BkF) was used for the initial activation of the AhR in the rainbow trout (Oncorhynchus mykiss) cell line RTL-W1. Pre-, co-, and post-exposure experiments with GO were performed and Cyp1A induction was monitored. The strong stimulation of Cyp1A observed in cells after exposure to GO, when BkF levels were not detected in the system, suggests a direct action of GO. The role of the AhR was confirmed by a blockage of the observed effects in co-treatment experiments with αNF (an AhR antagonist). These results suggest a possible role for the AhR and Cyp1A system in the cellular metabolism of GO and that GO could modulate the toxicity of environmental pollutants.

Sequential exposures of single walled carbon nanotubes and heavy metal ions to macrophages induce different cytotoxicity

The probability of occupational exposure rises with the increasing production and biomedical application of carbon nanotubes (CNTs). Thus, the risk of co-exposure of nanomaterials with environmental pollutants is also increasing. Although many studies have focused on the combined toxicity of nanomaterials and pollutants, more attention has been paid to the toxicity of nanomaterials after adsorbing pollutants or the toxicity of nanomaterials and pollutants exposed simultaneously. Few studies have been conducted on the toxicity and toxicity mechanisms of nanomaterials and environmental pollutants following sequential exposure. In this study, we employed THP-1 cells to investigate how pristine single walled CNTs (p-SWCNTs) and oxidized single walled CNTs (SWCNT-COOHs) pretreatments at a non-lethal dose of 10 μg/mL affect cell responses to metal ions (i. e., Pb²⁺, Cu²⁺, and Cr(VI)). We found that p-SWCNTs caused more significant damage to cell membrane integrity than SWCNT-COOHs, which led to higher metallothionein (MT) levels and increased transport of metal ions into cells. Pretreatment of p-SWCNTs in cells significantly increased the cytotoxicity of Pb²⁺, Cu²⁺, and Cr(VI) by 2-4-fold, whereas SWCNT-COOHs pretreated cells showed no noteworthy changes in response to heavy metals, which were further confirmed by the cellular reactive oxygen species (ROS) assays. These findings indicate that understanding the effects of the exposure sequence of engineered nanomaterials and environmental pollutants on their toxicity provides an excellent complement to combined toxicity evaluation.

In vitro and in vivo toxicological evaluation of carbon quantum dots originating from Spinacia oleracea

Food-derived carbon quantum dots (CQDs) can relatively easily be synthesized and chemically manipulated for a broad spectrum of biomedical applications. However, their toxicity may hinder their actual use. Here, Spinacia oleracea-derived CQDs i.e., CQD-1 and CQD-2, were synthesized by means of different shredding methods and followed by a microwave-assisted hydrothermal approach. Subsequently, these CQDs were analyzed in vitro and in an in vivo mice model to test their biocompatibility and potential use as bioimaging agents and for activation of osteogenic differentiation. When comparing CQD-1 and CQD-2, it was found that CQD-1 exhibited 7.6 times higher photoluminescent (PL) emission intensity around 411 nm compared to CQD-2. Besides, it was found that the size distribution of CQD-1 was 2.05 ± 0.08 nm, compared with 2.14 ± 0.04 nm for CQD-2. Upon exposure to human bone marrow-derived mesenchymal stem cells (hBMSCs) in vitro, CQD-1 was endocytosed into the cytoplasm and significantly increased the differentiation of hBMSCs up to 10 μg mL^-1 after 7 and 14 days. Apparently, the presence of relatively low doses of CQD-1 showed virtually no toxic or histological effects in the major organs in vivo. In contrast, high doses of CQD-1 (1 mg mL^-1) caused cell death in vitro ranging from 35% on day 1 to 80% on day 3 post-exposure, and activated the apoptotic machinery and increased lymphocyte aggregates in the liver tissue. In conclusion, S. oleracea-derived CQDs have the potential for biomedical applications in bioimaging and activation of stem cells osteogenic differentiation. Therefore, it is postulated that CQD-1 from S. oleracea remains potential prospective material at appropriate doses and specifications.

Environmental Implications Associated with the Development of Nanotechnology: From Synthesis to Disposal

Nanotechnology remains under continuous development. The unique, fascinating, and tunable properties of nanomaterials make them interesting for diverse applications in different fields such as medicine, agriculture, and remediation. However, knowledge about the risks associated with nanomaterials is still poorly known and presents variable results. Furthermore, the interaction of nanomaterials with biological systems and the environment still needs to be clarified. Moreover, some issues such as toxicity, bioaccumulation, and physicochemical transformations are found to be dependent on several factors such as size, capping agent, and shape, making the comparisons even more complex. This review presents a comprehensive discussion about the consequences of the use and development of nanomaterials regarding their potential risks to the environment as well as human and animal health. For this purpose, we reviewed the entire production chain from manufacturing, product development, applications, and even product disposal to raise the important implications at each stage. In addition, we present the recent developments in terms of risk management and the recycling of nanomaterials. Furthermore, the advances and limitations in the legislation and characterization of nanomaterials are also discussed.

In vitro toxicity of carbon nanotubes: a systematic review

Carbon nanotube (CNT) toxicity-related issues provoke many debates in the scientific community. The controversial and disputable data about toxicity doses, proposed hazard effects, and human health concerns significantly restrict CNT applications in biomedical studies, laboratory practices, and industry, creating a barrier for mankind in the way of understanding how exactly the material behaves in contact with living systems. Raising the toxicity question again, many research groups conclude low toxicity of the material and its potential safeness at some doses for contact with biological systems. To get new momentum for researchers working on the intersection of the biological field and nanomaterials, i.e., CNT materials, we systematically reviewed existing studies with in vitro toxicological data to propose exact doses that yield toxic effects, summarize studied cell types for a more thorough comparison, the impact of incubation time, and applied toxicity tests. Using several criteria and different scientific databases, we identified and analyzed nearly 200 original publications forming a "golden core" of the field to propose safe doses of the material based on a statistical analysis of retrieved data. We also differentiated the impact of various forms of CNTs: on a substrate and in the form of dispersion because in both cases, some studies demonstrated good biocompatibility of CNTs. We revealed that CNTs located on a substrate had negligible impact, i.e., 90% of studies report good viability and cell behavior similar to control, therefore CNTs could be considered as a prospective conductive substrate for cell cultivation. In the case of dispersions, our analysis revealed mean values of dose/incubation time to be 4-5 μg mL-1 h-1, which suggested the material to be a suitable candidate for further studies to get a more in-depth understanding of its properties in biointerfaces and offer CNTs as a promising platform for fundamental studies in targeted drug delivery, chemotherapy, tissue engineering, biosensing fields, etc. We hope that the present systematic review will shed light on the current knowledge about CNT toxicity, indicate "dark" spots and offer possible directions for the subsequent studies based on the demonstrated here tabulated and statistical data of doses, cell models, toxicity tests, viability, etc.

Caffeic acid protects mice pancreatic islets from oxidative stress induced by multi-walled carbon nanotubes (MWCNTs)

Increasing applications of carbon nanotubes (CNTs) indicate the necessity to examine their toxicity. According to previous studies, CNTs caused oxidative stress that impaired β-cell functions and reduced insulin secretion. Our previous study indicated that single-walled carbon nanotubes (SWCNTs) could induce oxidative stress in pancreatic islets. However, there is no study on the effects of multi-walled carbon nanotubes (MWCNTs) on islets and β-cells. Therefore, the present study aims to evaluate effects of MWCNTs on the oxidative stress of islets and the protective effects of caffeic acid (CA) as an antioxidant. The effects of MWCNTs and CA on islets were investigated using MTT assay, reactive oxygen species (ROS), malondialdehyde (MDA), activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), the content of glutathione (GSH) and mitochondrial membrane potential (MMP) and insulin secretion measurements. The lower viability of islet cells was dose-dependent due to the exposure to MWCNTs according to the MTT assay. Further studies revealed that MWCNTs decreased insulin secretion and MMP, induced ROS creation, increased the MDA level, and decreased activities of SOD, GSH-Px, CAT, and content of GSH. Furthermore, the pretreatment of islets with CA returned the changes. These findings indicated that MWCNTs might induce the oxidative stress of pancreatic islets occurring diabetes and protective CA effects that were mediated by the augmentation of the antioxidant defense system of islets. Our research suggested the necessity of conducting further studies on effects of MWCNTs and CA on the diabetes.

Spermatotoxic Effects of Single-Walled and Multi-Walled Carbon Nanotubes on Male Mice

Carbon-based nanomaterials possess a remarkably high potential for biomedical applications due to their physical properties; however, their detrimental effects on reproduction are also concerned. Several reports indicate the toxicity of carbon nanotubes (CNT); nevertheless, their impact on intracellular organelles in the male reproductive organs has not been fully elucidated. Herein, we report on the reprotoxicity of single-walled (SWCNT) and multi-walled carbon nanotubes (MWCN) on several intracellular events and histological criteria in pubertal male BALB/c mice orally treated with 0, 10, and 50 mg/kg/day doses for 5 weeks. Biomarkers of oxidative stress and mitochondrial functionality, histopathological alterations, and epididymal sperm characteristics were determined. Oral administration of CNTs at 10 and 50 mg/kg evoked a significant decrement in weight coefficient, sperm viability and motility, hypo-osmotic swelling (HOS) test, sperm count, mitochondrial dehydrogenase activity, ATP content, total antioxidant capacity, and GSH/GSSH ratio in the testis and epididymal spermatozoa. On the other hand, percent abnormal sperm, testicular and sperm TBARS contents, protein carbonylation, ROS formation, oxidized glutathione level, and sperm mitochondrial depolarization were considerably increased. Significant histopathological and stereological alterations in the testis occurred in the groups challenged with CNTs. The current findings indicated that oxidative stress and mitochondrial impairment might substantially impact CNTs-induced reproductive system injury and sperm toxicity. The results can also be used to establish environmental standards for CNT consumption by mammals, produce new chemicals for controlling the rodent populations, and develop therapeutic approaches against CNTs-associated reproductive anomalies in the males exposed daily to these nanoparticles.

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.

Comparing in vitro cytotoxicity of graphite, short multi-walled carbon nanotubes, and long multi-walled carbon nanotubes

Occupational and environmental exposures to carbon-based materials in nano- and micro-size have been reported. There is incomplete information on the impact of size on the toxicity of carbon-based materials. The objective of this study is to compare the toxicity of graphite, short multi-walled carbon nanotubes (S-MWCNTs), and long multi-walled carbon nanotubes (L-MWCNTs) in lung cells (A 549). The physicochemical properties of MWCNTs were determined using analytical instruments. The fibers of MWCNTs were dispersed in the sterile-filtered 0.05% bovine serum albumin in MilliQ water. Cytotoxicity of graphite and MWCNTs were assessed using the cell viability, reactive oxygen species (ROS), and lipid peroxidation experiments. Results showed that MWCNTs induced cytotoxicity through the generation of oxidative stress in the exposed lung cells. Mean cytotoxicity of S-MWCNTs was statistically more than that of L-MWCNTs. The graphite induced cytotoxicity only at high concentrations. The mean cytotoxicity of both S-MWCNTs and L-MWCNTs was statistically more than that of graphite. The results also indicated that oxidative stress was the probable toxicity mechanism of carbon-based materials. The decreasing size of carbon-based materials could increase their toxicity. Because of the toxicity of MWCNTs, it is imperative to consider health and safety issues in working with nanomaterials.

Multi-walled carbon nanotubes induce oxidative stress, apoptosis, and dysfunction in isolated rat heart mitochondria: protective effect of naringin

Multi-walled carbon nanotubes (MWCNTs) are material with exclusive features that can be applied in different fields including industrial and medicine. It has been determined that the accumulation of MWCNTs in the organs is along with genotoxic and cytotoxic injuries. Previous studies have shown mitochondrial dysfunction in MWCNTs exposure with cell lines, but their exact mechanisms with isolated mitochondria have remained unclear. The present study evaluated toxicity induced by MWCNTs in isolated rat heart mitochondria and protective effect of naringin. Our results showed that MWCNTs toxicity caused the prevention of heart mitochondrial complex II activity. Treatment of isolated heart mitochondria with MWCNTs led to an increase in mitochondrial reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP) collapse, and mitochondrial malondialdehyde (MDA) and a decrease in mitochondrial glutathione (GSH) level and mitochondrial catalase (CAT) activity. Pretreatment of isolated heart mitochondria with naringin decreased mitochondrial oxidative damage through decreasing lipid peroxidation, returned mitochondrial complex II changes, decreasing MMP collapse and ROS production, and restoration of GSH level and CAT activity. Our findings indicated that MWCNTs had toxic effects on isolated heart mitochondria by inducing oxidative stress and possibly apoptosis pathway. The protection effects of naringin may be accompanied by mitochondrial conservation by its antioxidant property or due to its free radical scavenging. Our findings indicated that naringin had a possible role in preventing the mitochondria complaints in the heart.

Genotoxicity assessment of triclocarban by comet and micronucleus assays and Ames test

The widespread usage and ubiquitous distribution of triclocarban (3,4,4'-trichlorocarbanilide, TCC) have raised public concerns about its health effects. At present, there is little information about the genotoxicity of TCC. In this study, we used a battery of genotoxicity testing methods including salmonella reverse mutation test (Ames test), comet assay and micronucleus assay to detect the effects of TCC on gene mutation, DNA breakage, and chromosome damage. The results of Ames test showed that TCC at 0.1-1000 μg/plate did not significantly increase the number of revertant colonies in the four standard Salmonella typhimurium strains, i.e., TA97, TA98, TA100, and TA102, when compared to the vehicle control. The results from comet assay demonstrated that exposure to 5, 10, or 15 μM TCC for 24 h did not significantly increase the percentage of comet cells, tail length (TL), DNA in tail (T DNA%), or olive tail moment (OTM) in keratinocyte HaCaT and hepatic L02 cells. Moreover, TCC did not markedly enhance the frequency of micronucleated cells or micronuclei in HaCaT and L02 cells in the micronucleus assay. Taken together, the results indicated that TCC did not exhibit any genotoxic effects. Our study provides additional information for the safety profile of TCC.

Effects of carbon nanotubes on biodegradation of pollutants: Positive or negative?

Recently, a large quantity of carbon nanotubes (CNTs) enters the environment due to the increasing production and applications. More and more researches are focused on the fate and possible ecological risks of CNTs. Some literatures summarized the effects of CNTs on the chemical behavior and fate of pollutants. However, little reviewed the effects of CNTs on the biodegradation of pollutants. In general, the effects of CNTs on the biodegradation of pollutants and the related mechanisms were summarized in this review. CNTs have positive or negative effects on the biodegradation of contaminants by affecting the functional microorganisms, enzymes and the bioavailability of pollutants. CNTs may affect the microbial growth, activity, biomass, community composition, diversity and the activity of enzymes. The decrease of the bioavailability of pollutants due to the sorption on CNTs also causes the reduction of the biodegradation of contaminants. In addition, the roles of CNTs are controlled by multiple mechanisms, which are divided into three aspects i.e., properties of CNTs, environment condition, and microorganisms themself. The better understanding of the fate of CNTs and their impacts on the biochemical process in the environment is conducive to determine the release of CNTs into the environment.

Triclocarban impairs autophagy in neuronal cells and disrupts estrogen receptor signaling via hypermethylation of specific genes

Although an increasing body of evidence suggests that triclocarban, a phenyl ether classified as a contaminant of emerging concern, presents a risk to development, there is limited data available on the potential interplay of triclocarban with the developing mammalian nervous system. This study was aimed to investigate the impact of environmentally pervasive chemical triclocarban on autophagy and estrogen receptor-mediated signaling pathways in mouse neurons. The study showed that triclocarban impaired autophagy and disrupted estrogen receptor signaling in mouse embryonic neurons in primary culture. Triclocarban used at environmentally relevant concentrations inhibited the mRNA and protein expression of ESR1 and GPER1 but not ESR2. The triclocarban-induced decrease in the expression of estrogen receptors was supported by the colocalization of the receptors in mouse neurons and corresponded to hypermethylation of the Esr1 and Gper1 genes. Selective antagonists increased the effects of triclocarban, which suggests that the neurotoxic effects of triclocarban, in addition to decreasing estrogen receptor expression, are mediated via inhibition of the neuroprotective capacity of the receptors. Furthermore, Becn1 and Atg7 siRNAs potentiated the caspase-3-dependent effect of triclocarban, which points to triclocarban-induced impairment of autophagy. Indeed, triclocarban dysregulated the expression of autophagy-related genes, and caused a time-dependent inhibition of the mRNA expression of Becn1, Map1lc3a, Map1lc3b, Nup62, and Atg7, which was correlated with a decrease in the protein levels of MAP1LC3B, BECN1 and autophagosomes, but not NUP62 protein level which was increased. Intriguingly, the Esr1 and Gper1 siRNAs did not affect the level of autophagosomes, suggesting that the triclocarban-induced impairment of autophagy is independent of the triclocarban-induced disruption of estrogen receptor signaling in mammalian neurons. Because our data provided evidence that triclocarban has the capacity to impair autophagy and disrupt estrogen receptor signaling in brain neurons at an early developmental stage, we postulate to categorize the compound as a neurodevelopmental risk factor.

Toxicity of Carbon Nanotubes as Anti-Tumor Drug Carriers

Nanoparticle drug formulations have enormous application prospects owing to achievement of targeted and sustained release drug delivery, improvement in drug solubility and reduction of adverse drug reactions. Recently, a variety of efficient drug nanometer carriers have been developed, among which carbon nanotubes (CNT) have been increasingly utilized in the field of cancer therapy. However, these nanotubes exert various toxic effects on the body due to their unique physical and chemical properties. CNT-induced toxicity is related to surface modification, degree of aggregation in vivo, and nanoparticle concentration. This review has focused on the potential toxic effects of CNTs utilized as anti-tumor drug carriers. The main modes by which CNTs enter target sites, the toxicity expressive types and the factors affecting toxicity are discussed.

Single-walled and multiwalled carbon nanotubes induce oxidative stress in isolated rat brain mitochondria

Single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) are broadly applicable across a variety of industrial fields. Despite their usefulness in many different applications, oxidative stress-induced toxicity of SWCNTs and MWCNTs has not been widely investigated. The present study examined the effects of SWCNTs and MWCNTs on rat brain mitochondria using the 3,4 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and indices of reactive oxygen species (ROS), based on measurements of malondialdehyde (MDA), glutathione (GSH), and mitochondrial membrane potential. Based on the MTT assay, exposure to SWCNTs and MWCNTs decreased mitochondrial survival and viability in a dose-dependent manner. Findings also indicated that MWCNTs and SWCNTs could damage mitochondrial membranes and induce the formation of ROS, as indicated by increased levels of MDA and decreased GSH content. The results of this study suggest that SWCNTs and MWCNTs likely damage brain tissue mitochondria by increasing oxidative stress and possibly activating the apoptosis pathway as well as other pathways of cytotoxicity.

Antagonistic effect of co-exposure to short-multiwalled carbon nanotubes and benzo[a]pyrene in human lung cells (A549)

In theenvironment, co-exposure to short-multiwalled carbon nanotubes (S-MWCNTs) and polycyclic aromatic compounds (PAHs) has been reported. In the co-exposure condition, the adsorption of PAHs onto MWCNTs may reduce PAHs toxic effect. The objective of this study was to investigate the cytotoxicity of S-MWCNTs and benzo[a]pyrene (B[a]P) individually, and in combination in human lung cell lines (A549). The adsorption of B[a]P onto MWCNTs was measured spectrometrically. In vitro toxicity was assessed through cell viability, reactive oxygen species (ROS) generation, apoptosis, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) generation experiments. The S-MWCNTs demonstrated cytotoxicity through the generation of ROS, apoptosis, and 8-OHdG in A549 cells. Co-exposure to S-MWCNTs and B[a]P demonstrated a significant reduction in ROS generation and apoptosis compared with the sum of their separate toxic effects at the same concentrations. Decreasing the bioavailability of B[a]P by MWCNT interaction is the probable reason for the antagonistic effects of the co-exposure condition. The findings of this study will contribute to a better understanding of the health effects of co-exposures to air pollutants and could be a starting point for modifying future health risk assessments.

Individual and combined toxicity of carboxylic acid functionalized multi-walled carbon nanotubes and benzo a pyrene in lung adenocarcinoma cells

Co-exposure to carboxylic acid functionalized multi-walled carbon nanotubes (F-MWCNTs) and polycyclic aromatic hydrocarbons (PAHs) such as benzo a pyrene (BaP) in ambient air have been reported. Adsorption of BaP to F-MWCNTs can influence combined toxicity. Studying individual toxicity of F-MWCNTs and BaP might give unrealistic data. Limited information is available on the combined toxicity of F-MWCNTs and BaP in human cells. The objective of the present work is to evaluate the toxicity of F-MWCNTs and BaP individually and combined in human lung adenocarcinoma (A549 cells). The in vitro toxicity is evaluated through cell viability, the production of reactive oxygen species (ROS), apoptosis, and the production of 8-OHdG assays. Adsorption of BaP to F-MWCNTs was confirmed using a spectrophotometer. The results indicated that the F-MWCNTs and BaP reduce cell viability individually and produce ROS, apoptosis, and 8-OHdG in exposed cells. Stress oxidative is found to be a mechanism of cytotoxicity for both F-MWCNTs and BaP. Combined exposure to F-MWCNTs and BaP decreases cytotoxicity compared to individual exposure, but the difference is not statistically significant in all toxicity assays; hence, the two-factorial analysis indicated an additive toxic interaction. Adsorption of BaP to F-MWCNTs could mitigate the bioavailability and toxicity of BaP in biological systems. Considering the mixture toxicity of MWCNTs and BaP is required for risk assessment of ambient air contaminants.

Endocytosis, intracellular fate, accumulation, and agglomeration of titanium dioxide (TiO2) nanoparticles in the rainbow trout liver cell line RTL-W1

There is increasing evidence that titanium dioxide (TiO2) nanoparticles (NPs) present in water or diet can be taken up by fish and accumulate in internal organs including the liver. However, their further fate in the organ is unknown. This study provides new insights into the interaction, uptake mechanism, intracellular trafficking, and fate of TiO2 NPs (Aeroxide® P25) in fish liver parenchymal cells (RTL-W1) in vitro using high-resolution transmission electron microscopy (TEM) and single particle inductively coupled plasma mass spectrometry (spICP-MS) as complementary analytical techniques. The results demonstrate that following their uptake via caveolae-mediated endocytosis, TiO2 NPs were trafficked through different intracellular compartments including early endosomes, multivesicular bodies, and late endosomes/endo-lysosomes, and eventually concentrated inside multilamellar vesicles. TEM and spICP-MS results provide evidence that uptake was nano-specific. Only NPs/NP agglomerates of a specific size range (~ 30-100 nm) were endocytosed; larger agglomerates were excluded from uptake and remained located in the extracellular space/exposure medium. NP number and mass inside cells increased linearly with time and was associated with an increase in particle diameter suggesting intracellular agglomeration/aggregation. No alterations in the expression of genes regulated by the redox balance-sensitive transcription factor Nrf-2 including superoxide dismutase, glutamyl cysteine ligase, glutathione synthetase, glutathione peroxidase, and glutathione S-transferase were observed. This shows that, despite the high intracellular NP burden (~ 3.9 × 102 ng Ti/mg protein after 24 h) and NP-interaction with mitochondria, cellular redox homeostasis was not significantly affected. This study contributes to a better mechanistic understanding of in vitro particokinetics as well as the potential fate and effects of TiO2 NPs in fish liver cells.

Does the exposure to salinity variations and water dispersible carbon nanotubes induce oxidative stress in Hediste diversicolor?

Salinity plays a fundamental role in naturally fluctuating environments such as estuaries influencing physiological and biochemical performance of inhabiting biota. Moreover salinity is considered one of the main factors influencing nanoparticles' stability. Thus, the aim of the present paper was to show the impacts induced by different salinities (control-28 and 21) on the chemical behavior of water dispersible multi-walled carbon nanotube (MWCNTs-COOH) and the consequent toxicity in the common ragworm Hediste diversicolor, after long term exposure. Results showed a concentration-dependent toxicity in terms of energy reserves and metabolism, oxidative status and neurotoxicity. In addition, under low salinity (21), the toxicity of the carbon NMs was similar to the impacts measured under control (28), although under salinity 28 the concentrations of MWCNTs-COOH used generated greater alterations in LPO levels and antioxidant enzymes (SOD and GPx). These results demonstrate that higher salinity caused the formation of large-size aggregates, which increased the chance of physical retention, such as gravitational sedimentation, interception and straining of f-MWCNTs generating higher cell injuries than the impacts induced in polychaetes sensitivity to these contaminates due to low salinity.

Graphene oxide conjugated with polymers: a study of culture condition to determine whether a bacterial growth stimulant or an antimicrobial agent?

Background

The results showed that the deciding factor is the culture medium in which the bacteria and the graphene oxide (GO) are incubated at the initial manipulation step. These findings allow better use of GO and GO-based materials more and be able to clearly apply them in the field of biomedical nanotechnology.

Results

To study the use of GO sheets applied in the field of biomedical nanotechnology, this study determines whether GO-based materials [GO, GO-polyoxyalkyleneamine (POAA), and GO-chitosan] stimulate or inhibit bacterial growth in detail. It is found that it depends on whether the bacteria and GO-based materials are incubated with a nutrient at the initial step. This is a critical factor for the fortune of bacteria. GO stimulates bacterial growth and microbial proliferation for Gram-negative and Gram-positive bacteria and might also provide augmented surface attachment for both types of bacteria. When an external barrier that is composed of GO-based materials forms around the surface of the bacteria, it suppresses nutrients that are essential to microbial growth and simultaneously produces oxidative stress, which causes bacteria to die, regardless of whether they have an outer-membrane-Gram-negative-bacteria or lack an outer-membrane-Gram-positive-bacteria, even for high concentrations of biocompatible GO-POAA. The results also show that these GO-based materials are capable of inducing reactive oxygen species (ROS)-dependent oxidative stress on bacteria. Besides, GO-based materials may act as a biofilm, so it is hypothesized that they suppress the toxicity of low-dose chitosan.

Conclusion

Graphene oxide is not an antimicrobial material but it is a general growth enhancer that can act as a biofilm to enhance bacterial attachment and proliferation. However, GO-based materials are capable of inducing ROS-dependent oxidative stress on bacteria. The applications of GO-based materials can clearly be used in antimicrobial surface coatings, surface-attached stem cells for orthopedics, antifouling for biocides and microbial fuel cells and microbial electro-synthesis.

Electronic supplementary material

The online version of this article (10.1186/s12951-017-0328-8) contains supplementary material, which is available to authorized users.

A growing world of small things: a brief review on the nanostructured vaccines

Vaccines are the most cost-effective intervention in the management of infectious disease. Much of what we perceive as quality of life is related to a good health status and disease absence, for which vaccines are substantially responsible. Nonetheless, there are many infectious diseases for which no vaccine solution is available. That could be due to limitations of the classic approaches to vaccine development, including inactivated, subunit and attenuated vaccines. Nanostructured immunogens belong to a class of nonclassic vaccines in which nanostructures are loaded with antigen-related molecules. Here, we briefly review important features of the nanostructured vaccines – mainly those based in carbon nanotubes and gold nanorods – and discuss their use to prevent infectious diseases, especially those caused by viruses.

Molecular links among non-biodegradable nanoparticles, reactive oxygen species, and autophagy

For nanoparticles to be successful in combating diseases in the clinic in the 21st century and beyond, they must localize to target areas of the body and avoid damaging non-target, healthy tissues. Both soft and stiff, bio-degradable and non-biodegradable nanoparticles are anticipated to be used to this end. It has been shown that stiff, non-biodegradable nanoparticles cause reactive oxygen species (ROS) generation and autophagy in a variety of cell lines in vitro. Both responses can lead to significant remodeling of the cytosol and even apoptosis. Thus these are crucial cellular functions to understand. Improved assays have uncovered crucial roles of the Akt/mTOR signaling pathway in both ROS generation and autophagy initiation after cells have internalized stiff, non-biodegradable nanoparticles over varying geometries in culture. Of particular - yet unresolved - interest is how these nanoparticles cause the activation of these pathways. This article reviews the most recent advances in nanoparticle generation of ROS and autophagy initiation with a focus on stiff, non-biodegradable technologies. We provide experimental guidelines to the reader for fleshing out the effects of their nanoparticles on the above pathways with the goal of tuning nanoparticle design.

Potential Developmental and Reproductive Impacts of Triclocarban: A Scoping Review

Triclocarban (TCC) is an antimicrobial agent used in personal care products. Although frequently studied with another antimicrobial, triclosan, it is not as well researched, and there are very few reviews of the biological activity of TCC. TCC has been shown to be a possible endocrine disruptor, acting by enhancing the activity of endogenous hormones. TCC has been banned in the US for certain applications; however, many human populations, in and outside the US, exhibit exposure to TCC. Because of the concern of the health effects of TCC, we conducted a scoping review in order to map the current body of literature on the endocrine, reproductive, and developmental effects of TCC. The aim of this scoping review was to identify possible endpoints for future systematic review and to make recommendations for future research. A search of the literature until August 2017 yielded 32 relevant studies in humans, rodents, fish, invertebrates, and in vitro. Based on the robustness of the literature in all three evidence streams (human, animal, and in vitro), we identified three endpoints for possible systematic review: estrogenic activity, androgenic activity, and offspring growth. In this review, we describe the body of evidence and make recommendations for future research.

Fish cell lines as a tool for the ecotoxicity assessment and ranking of engineered nanomaterials

Risk assessment of engineered nanomaterials (ENMs) is being hindered by the sheer production volume of these materials. In this regard, the grouping and ranking of ENMs appears as a promising strategy. Here we sought to evaluate the usefulness of in vitro systems based on fish cell lines for ranking a set of ENMs on the basis of their cytotoxicity. We used the topminnow (Poeciliopsis lucida) liver cell line (PLHC-1) and the rainbow trout (Oncorhynchus mykiss) fibroblast-like gonadal cell line (RTG-2). ENMs were obtained from the EU Joint Research Centre repository. The size frequency distribution of ENM suspensions in cell culture media was characterized. Cytotoxicity was evaluated after 24 h of exposure. PLHC-1 cells exhibited higher sensitivity to the ENMs than RTG-2 cells. ZnO-NM was found to exert toxicity mainly by altering lysosome function and metabolic activity, while multi-walled carbon nanotubes (MWCNTs) caused plasma membrane disruption at high concentrations. The hazard ranking for toxicity (ZnO-NM > MWCNT ≥ CeO₂-NM = SiO₂-NM) was inversely related to the ranking in size detected in culture medium. Our findings reveal the suitability of fish cell lines for establishing hazard rankings of ENMs in the framework of integrated approaches to testing and assessment.

Multi-walled carbon nanotubes functionalized with recombinant Dengue virus 3 envelope proteins induce significant and specific immune responses in mice

BACKGROUND

Dengue is the most prevalent arthropod-borne viral disease in the world. In this article we present results on the development, characterization and immunogenic evaluation of an alternative vaccine candidate against Dengue.

METHODS

The MWNT-DENV3E nanoconjugate was developed by covalent functionalization of carboxylated multi-walled carbon nanotubes (MWNT) with recombinant dengue envelope (DENV3E) proteins. The recombinant antigens were bound to the MWNT using a diimide-activated amidation process and the immunogen was characterized by TEM, AFM and Raman Spectroscopy. Furthermore, the immunogenicity of this vaccine candidate was evaluated in a murine model.

RESULTS

Immunization with MWNT-DENV3E induced comparable IgG responses in relation to the immunization with non-conjugated proteins; however, the inoculation of the nanoconjugate into mice generated higher titers of neutralizing antibodies. Cell-mediated responses were also evaluated, and higher dengue-specific splenocyte proliferation was observed in cell cultures derived from mice immunized with MWNT-DENV3E when compared to animals immunized with the non-conjugated DENV3E.

CONCLUSIONS

Despite the recent licensure of the CYD-TDV dengue vaccine in some countries, results from the vaccine's phase III trial have cast doubts about its overall efficacy and global applicability. While questions about the effectiveness of the CYD-TDV vaccine still lingers, it is wise to keep at hand an array of vaccine candidates, including alternative non-classical approaches like the one presented here.

Electrically conductive hydrogel-based micro-topographies for the development of organized cardiac tissues

In this study, we developed conductive microgrooved tissue constructs, leading to the formation of highly packed and uniaxially oriented cardiac cytoarchitecture.

Review of key factors controlling engineered nanoparticle transport in porous media

Nanotechnology, an emerging technology, has witnessed rapid development in production and application. Engineered nanomaterials revolutionize the industry due to their unique structure and superior performance. The release of engineered nanoparticles (ENPs) into the environment, however, may pose risks to the environment and public health. To advance current understanding of environmental behaviors of ENPs, this work provides an introductory overview of ENP fate and transport in porous media. It systematically reviews the key factors controlling their fate and transport in porous media. It first provides a brief overview of common ENPs in the environment and their sources. The key factors that govern ENP transport in porous media are then categorized into three groups: (1) nature of ENPs affecting their transport in porous media, (2) nature of porous media affecting ENP transport, and (3) nature of flow affecting ENP transport in porous media. In each group, findings in recent literature on the specific governing factors of ENP transport in porous media are discussed in details. Finally, this work concludes with remarks on the importance of ENP transport in porous media and directions for future research.

The ecotoxic potential of a new zero-valent iron nanomaterial, designed for the elimination of halogenated pollutants, and its effect on reductive dechlorinating microbial communities

The purpose of this study was to assess the ecotoxic potential of a new zero-valent iron nanomaterial produced for the elimination of chlorinated pollutants at contaminated sites. Abiotic dechlorination through the newly developed nanoscale zero-valent iron material and its effects on dechlorinating bacteria were investigated in anaerobic batch and column experiments. The aged, i.e. oxidized, iron material was characterization with dynamic light scattering, transmission electron microscopy and energy dispersive x-ray analysis, x-ray diffractometry and cell-free reactive oxygen measurements. Furthermore, it was evaluated in aerobic ecotoxicological test systems with algae, crustacean, and fish, and also applied in a mechanism specific test for mutagenicity. The anaerobic column experiments showed co-occurrence of abiotic and biological dechlorination of the common groundwater contaminant perchloroethene. No prolonged toxicity of the nanomaterial (measured for up to 300 days) towards the investigated dechlorinating microorganism was observed. The nanomaterial has a flake like appearance and an inhomogeneous size distribution. The toxicity to crustacean and fish was calculated and the obtained EC50 values were 163 mg/L and 458 mg/L, respectively. The nanomaterial showed no mutagenicity. It physically interacted with algae, which had implications for further testing and the evaluation of the results. Thus, the newly developed iron nanomaterial was slightly toxic in its reduced state but no prolonged toxicity was recorded. The aquatic tests revealed a low toxicity with EC50 values ≥ 163 mg/L. These concentrations are unlikely to be reached in the aquatic environment. Hence, this nanomaterial is probably of no environmental concern not prohibiting its application for groundwater remediation.

Release of (14)C-labelled carbon nanotubes from polycarbonate composites

Waste disposal of carbon nanotube (CNT) containing products is expected to be the most important pathway for release of CNTs into the environment. In the present work, the use of radiolabelled CNTs ((14)C-CNT) for polycarbonate polymer nanocomposites with 1 wt% (14)C-CNT content allowed for the first time to quantify and differentiate the CNT release according to the type of impact along the materials' ageing history. After an initial exposure of the nanocomposite by solar-like irradiation, further environmental impacts were applied to composite material. They aimed at mimicking disposal site conditions that may induce further ageing effects and CNT release. This study included shaking in water, rapid temperature changes, soaking in humic acid solution as well as waste water effluent, and, finally, gentle mechanical abrasion. All ageing impacts were applied sequentially, both on pristine (control) and on solar-irradiated nanocomposites. All experiments were accompanied by absolute quantification of radioactive release as well as chemical and morphological analyses of the nanocomposite surfaces using infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The morphological analysis showed that spectral irradiation can uncover CNT networks on the outer nanocomposite surface layers by polymer degradation. After having subjected the solar-irradiated nanocomposite to all studied disposal site effect, the total radioactive release was quantified to amount to 64 mg CNT/m(2), whereas only 0.8 mg CNT/m(2) were found for the un-irradiated control sample. Solar degradation of polymers was thus found to significantly increase the propensity of the studied polymer nanocomposites to release CNTs during ageing effects at the product's end-of-life typical for disposal sites.

Population level effects of multiwalled carbon nanotubes in Daphnia magna exposed to pulses of triclocarban

Due to the rapid increase of carbon nanotubes (CNT) applications and their inevitable release into the aquatic environment, CNT may interact with and further influence the fate and transport of other pollutants such as triclocarban (TCC). TCC is a high-production-volume chemical that is widely used as an antimicrobial agent, is continually released into the aquatic environment, and is biologically active and persistent. In the present study, the population test with Daphnia magna was performed over 93 days. Different treatments were examined: (a) control, (b) solvent control, (c) 1 mg CNT/L from the beginning, (d) 1 mg CNT/L as of day 14, (e) control with a 2-day pulse of 25 µg TCC/L on day 14, 41 µg TCC/L (day 54), and 61 µg TCC/L (day 68) and (f) same pulses of TCC with co-exposure to 1 mg CNT/L. Significant changes in all three size classes were observed as a result of the long-term exposure to 1 mg CNT/L. Increasing in number of neonates, and decreasing in number of juveniles and adults were observed. Moreover, daphnids were significantly smaller when they were exposed to MWCNT. The exposure with TCC led to size-dependent mortality in Daphnia magna populations and a subsequent recovery. Lower toxicity of TCC was observed, with the presence of MWCNT in the medium. The reported effects of TCC on population level were compared to the output of an individual-based Daphnia magna population model, in order to verify the model predictions with laboratory data.