Toxicity Evaluation of Graphene Oxide and Titania Loaded Nafion Membranes in Zebrafish

Environmental pollutant sodium omadine: toxic effects in zebra fish (Danio rerio)

In recent years one of the most striking results of over-population and consumption activities in the world is the rapid increase in environmental pollutants. Environmental pollutants, one of the harmful consequences of technological and modern life, threaten the health of people and other living organisms. In this study, we aimed to determine the effects of sodium omadine (NaOM) on superoxide dismutase enzyme (SOD) activity as an antioxidant and on 8-OHdG levels as oxidative DNA damage in zebrafish. Zebrafish, obtained from the aquarium fish producer, were stocked in experimental aquariums to ensure their adaptation period to the experimental conditions 15 days before the experiment. The fish were exposed to 1 ug/L and 5 ug/L concentrations of NaOM for 24, 72, and 96 h. SOD enzyme activity (U/100 mg tissue) and 8-OHdG (pg/100 mg tissue) were measured using commercial kits. The statistically significant differences in tissue SOD levels and data for DNA damage between the groups were determined as time and dose-dependent (p < 0.05). Biocidal products are environmental pollutants that cause changes in antioxidant enzyme activities, especially in non-target organisms. Marine pollution and the degradation of ecosystems directly affect people, and the results of the study offer awareness of health problems, environmental pollution, and marine pollution.

Anti-bacterial and anti-inflammatory properties of Vernonia arborea accelerate the healing of infected wounds in adult Zebrafish

BACKGROUND

Management of wounds and healing under impaired conditions are the major challenges faced globally by healthcare workers. Phytocompounds which are anti-microbial and capable of modulating inflammation contribute to overall wound healing and regain of the lost structure and function especially in wounds impaired with polymicrobial infection.

METHODS

An acute cutaneous impaired wound model using adult zebrafish was validated to simulate mammalian wound pathophysiology. This model was used to evaluate phytofractions of Vernonia arborea in the present study, for reduction of infection; myeloperoxidase (MPO) as a marker of infection; neutrophil infiltration and resolution; kinetics of inflammatory cytokines; and wound repair kinetics (viz., nitrite levels and iNoS expression; reepithelisation).

RESULTS

Four fractions which were active in-vitro against five selected wound microbes were shown to reduce ex-vivo microbial bioburden upto 96% in the infected wound tissue. The reduction in CFU correlated with the neutrophil kinetics and MPO enzyme levels in the treated, wound infected zebrafish. Expression of pro-inflammatory cytokines (IL-6 and TNF-α) was downregulated while upregulating anti-inflammatory cytokine (IL-10), and nitric oxide signalling with fourfold increase in iNOS expression. The adult zebrafish wound model could well serve as a standard tool for assessing phytoextracts such as V. arborea for wound healing with anti-microbial properties.

Hazard and health risk assessment of exposure to pharmaceutical active compounds via toxicological evaluation by zebrafish

The uncontrolled or continuous release of effluents from wastewater treatment plants leads to the omnipresence of pharmaceutical active compounds (PhACs) in the aquatic media. Today, this is a confirmed problem becoming a main subject of twin public and scientific concerns. However, still little information is available about the long-term impacts of these PhACs on aquatic organisms. In this review, efforts were made to reveal correlation between the occurrence in the environment, ecotoxicological and health risks of different PhACs via toxicological evaluation by zebrafish (Danio rerio). This animal model served as a bioindicator for any health impacts after the exposure to these contaminants and to better understand the responses in relation to human diseases. This review paper focused on the calculation of Risk Quotients (RQs) of 34 PhACs based on environmental and ecotoxicological data available in the literature and prediction from the ECOSAR V2.2 software. To the best of the authors' knowledge, this is the first report on the risk assessment of PhACs by the two different methods as mentioned above. RQs showed greater difference in potential environmental risks of the PhACs. These differences in risk values underline the importance of environmental and experimental factors in exposure conditions and the interpretation of RQ values. While the results showed high risk to Danio rerio of the majority of PhACs, risk qualification of the others varied between moderate to insignifiant. Further research is needed to assess pharmaceutical hazards when present in wastewater before discharge and monitor the effectiveness of treatment processes. The recent new advances in the morphological assessment of toxicant-exposed zebrafish larvae for the determination of test compounds effects on the developmental endpoints were also discussed. This review emphasizes the need for strict regulations on the release of PhACs into environmental media in order to minimize their toxicity to aquatic organisms.

An Update on Graphene Oxide: Applications and Toxicity

Graphene oxide (GO) has attracted much attention in the past few years because of its interesting and promising electrical, thermal, mechanical, and structural properties. These properties can be altered, as GO can be readily functionalized. Brodie synthesized the GO in 1859 by reacting graphite with KClO3 in the presence of fuming HNO3; the reaction took 3-4 days to complete at 333 K. Since then, various schemes have been developed to reduce the reaction time, increase the yield, and minimize the release of toxic byproducts (NO2 and N2O4). The modified Hummers method has been widely accepted to produce GO in bulk. Due to its versatile characteristics, GO has a wide range of applications in different fields like tissue engineering, photocatalysis, catalysis, and biomedical applications. Its porous structure is considered appropriate for tissue and organ regeneration. Various branches of tissue engineering are being extensively explored, such as bone, neural, dentistry, cartilage, and skin tissue engineering. The band gap of GO can be easily tuned, and therefore it has a wide range of photocatalytic applications as well: the degradation of organic contaminants, hydrogen generation, and CO2 reduction, etc. GO could be a potential nanocarrier in drug delivery systems, gene delivery, biological sensing, and antibacterial nanocomposites due to its large surface area and high density, as it is highly functionalized with oxygen-containing functional groups. GO or its composites are found to be toxic to various biological species and as also discussed in this review. It has been observed that superoxide dismutase (SOD) and reactive oxygen species (ROS) levels gradually increase over a period after GO is introduced in the biological systems. Hence, GO at specific concentrations is toxic for various species like earthworms, Chironomus riparius, Zebrafish, etc.

Review: Mytilus galloprovincialis: An essential, low-cost model organism for the impact of xenobiotics on oxidative stress and public health

The level of pollution becomes more and more of a pressuring matter for humankind at a worldwide level. Often the focus is on the effects that we can directly and see such as decreased air quality and higher than normal temperatures and weather, but the effects we cannot see are frequently overlooked. For at least the past decade increasing importance has been given towards the effects of pollution of living animals or non-target organisms and plants. For this purpose, one model animal that surfaced is the purpose, one model animal surfaced is Mytilus galloprovincialis. As all mussels, this species is capable of bio-accumulating important quantities of different xenobiotics such as pesticides, paints, medicines, heavy metals, industrial compounds, and even compounds marketed as antioxidants and antivirals. Their toxic effects can be assessed through their impact on oxidative stress, lysosomal membrane stability, and cell viability through trypan blue exclusion test and neutral red retention assay techniques. The purpose of this paper is to highlight the benefits of using M. galloprovincialis as an animal model for toxicological assays of various classes of xenobiotics by bringing to light the studies that have approached the matter.

Biological Effects Assessment of Antibiofouling EDCs: Gaeta Harbor (South Italy) Benthic Communities' Analysis by Biodiversity Indices and Quantitative gpx4 Expression

The most representative organisms of the Harbor of Gaeta Gulf in South Italy were analyzed for biofouling by visual census and confirmed later by molecular approach on an artificial Conatex panel dipped 3 m into a eutrophic area during the Covid-19 pandemic. Mitochondrial Cytochrome C oxidase subunit 1(COI) gene was sequenced from 20 different marine species (flora: 2 families, 2 orders; fauna: 16 families, 11 orders) to test whether the morphology-based assignment of the most common biofouling member was supported by DNA-based species identification. Twelve months of submersion resulted in generation of sufficient data to obtain a facies climax represented mainly by the bivalve mollusk, Mytilus galloprovincialis. Specific diversity and variations of the biofouling biomasses were analyzed using two different anti-biofouling paints: an endocrine disrupting chemical (EDC)-containing metal biocide, and a biocide-free paint. Also, their effects on detoxification and reproductive health of M. galloprovincialis were evaluated using glutathione S-transferase enzymatic activity and RTqPCR expression of the fertility antioxidant gene glutathione peroxidase 4 (gpx4). The obtained data provide useful indications on which future investigations may be focused and may become a potential management tool for a harbor biofouling database to assist local administrations in EDCs protection of autochthonous benthic communities and their fertility using innovative antifouling paints.

Efficiency of marketable decontamination agent and graphene oxide on 99mTc and 131I spillages in nuclear medicine department

Dealing with open sources of radioactive substances in nuclear medicine is a daily task since contamination due to radioactive spills may happen frequently. Proper and safe decontamination management is a vital procedure. However, regular purchase of decontamination agents incurs high costs and might be toxic due to their chemical properties. The purpose of this study is to compare graphene oxide, which is an environmentally friendly carbon-based material and marketable decontamination agent, in decontaminating radioactive spillage. Samples of pure 99mTc and 131I from the laboratory were spilled on a petri dish. The spill was immediately decontaminated with a marketable decontamination agent swab and varying concentrations of graphene oxide swab. The initial radioactivity of each swab containing 99mTc and 131I was measured using a dose calibrator. The absorbance spectra of each sample were analysed using an ultraviolet-visible spectrophotometer. The morphology image of graphene oxide was observed under field emission scanning electron microscope. For decontamination using a marketable decontamination agent, the radioactivity of 131I was slightly higher, whereas that of 99mTc was slightly lower than the high concentration of graphene oxide. The absorbance spectra of 99mTc and 131I that had been decontaminated using graphene oxide were observed at a range of 200 nm to 250 nm due ???* to the transition.

Uptake and effects of graphene oxide nanomaterials alone and in combination with polycyclic aromatic hydrocarbons in zebrafish

Because of its surface characteristics, once in the aquatic environment, graphene could act as a carrier of pollutants, such as polycyclic aromatic hydrocarbons (PAHs), to aquatic organisms. In this study we aimed to (1) assess the capacity of graphene oxide (GO) to sorb PAHs and (2) to evaluate the toxicity of GO alone and in combination with PAHs on zebrafish embryos and adults. GO showed a high sorption capacity for benzo(a)pyrene (B(a)P) (98% of B(a)P sorbed from a nominal concentration of 100 μg/L) and for other PAHs of the water accommodated fraction (WAF) of a naphthenic North Sea crude oil, depending on their log K_ow (95.7% of phenanthrene, 84.4% of fluorene and 51.5% of acenaphthene). In embryos exposed to different GO nanomaterials alone and with PAHs, no significant mortality was recorded for any treatment. Nevertheless, malformation rate increased significantly in embryos exposed to the highest concentrations (5 or 10 mg/L) of GO and reduced GO (rGO) alone and with sorbed B(a)P (GO-B(a)P). On the other hand, adults were exposed for 21 days to 2 mg/L of GO, GO-B(a)P and GO co-exposed with WAF (GO + WAF) and to 100 μg/L B(a)P. Fish exposed to GO presented GO in the intestine lumen and liver vacuolisation. Transcription level of genes related to cell cycle regulation and oxidative stress was not altered, but the slight up-regulation of cyp1a measured in fish exposed to B(a)P for 3 days resulted in a significantly increased EROD activity. Fish exposed to GO-B(a)P and to B(a)P for 3 days and to GO + WAF for 21 days showed significantly higher catalase activity in the gills than control fish. Significantly lower acetylcholinesterase activity, indicating neurotoxic effects, was also observed in all fish treated for 21 days. Results demonstrated the capacity of GO to carry PAHs and to exert sublethal effects in zebrafish.

Toxicological assessment of CeO2 nanoparticles on early development of zebrafish

Nanomaterials involve an active research and a booming area including different fields (health, environment, electronics, manufacturing, drug delivery). Recently, new concerns are emerging about the risk from increased production and subsequent release into the environment, as they are largely present in consumer products and industrial applications. Our aim was to assess the effects of three different types of cerium oxide nanoparticles (CeO2 NPs) (type 1 defined "as prepared"; type 2 defined "modified"; type 3 defined "commercial") on zebrafish embryos by Fish Embryo Toxicity test (Z-FET). Immunohistochemical analysis was also performed on treated larvae to evaluate the expression of the following biomarkers: Metallothionein, Heat Shock Protein 70 (HSP70) and 7-Ethoxyresorufin-O-Dietylase (EROD). After 96 h of exposure, there was no lethality, nor were there sub-lethal effects in embryonic development, when compared with the control. No particular positivity was found about Metallothionein and HSP70 expression, while an increased expression of EROD was observed in larvae exposed to the three types of CeO2 NPs compared with the controls. The analyze has confirmed a statistically significant difference (P < 0.001) to EROD biomarker between control group and treated larvae response, finding was higher at 1-mg/l concentration. Further investigations in order to solve conflicting views about potential effects of CeO2 NPs are necessary, also to evaluate its effectiveness in different fields as already reported in literature.

Toward High-Throughput Fish Embryo Toxicity Tests in Aquatic Toxicology

Addressing the shift from classical animal testing to high-throughput in vitro and/or simplified in vivo proxy models has been defined as one of the upcoming challenges in aquatic toxicology. In this regard, the fish embryo toxicity test (FET) has gained significant popularity and wide standardization as one of the sensitive alternative approaches to acute fish toxicity tests in chemical risk assessment and water quality evaluation. Nevertheless, despite the growing regulatory acceptance, the actual manipulation, dispensing, and analysis of living fish embryos remains very labor intensive. Moreover, the FET is commonly performed in plastic multiwell plates under static or semistatic conditions, potentially inadequate for toxicity assessment of some organic, easily degradable or highly adsorptive toxicants. Recent technological advances in the field of mechatronics, fluidics and digital vision systems demonstrate promising future opportunities for automation of many analytical stages in embryo toxicity testing. In this review, we highlight emerging advances in fluidic and laboratory automation systems that can prospectively enable high-throughput FET testing (HT-FET) akin to pipelines commonly found in in vitro drug discovery pipelines. We also outline the existing challenges, barriers to future development and provide an outlook of ground-breaking fluidic technologies in embryo toxicity testing.

Oxidative stress in Ruditapes philippinarum after exposure to different graphene oxide concentrations in the presence and absence of sediment

The use of carbon nanomaterials (CNMs) is growing in different technological fields, raising concern on their potential impacts on the environment. Given its diverse nanothenological applications, graphene oxide (GO) stands out among the most widely used CNMs. Its hydrophilic capacity enables it to remain stable in suspension in water allowing that GO can be accessible for accumulation by aquatic organisms through ingestion, filtration and superficial dermal contact when present in aquatic ecosystems. Considering that the effects induced to aquatic organisms may depend on environment characteristics, such as temperature, salinity, water pH as well as the presence/absence of sediment, the present study aimed to investigate the influence of sediment on the impacts caused by GO exposure. For this, oxidative stress parameters were measured in the clam Ruditapes philippinarum, exposed to different GO concentrations (0.01, 0.1 and 1 mg/L), in the presence and absence of sediment, for a 28-days experimental period. The results here presented showed that regardless the presence or absence of sediment, most of the biochemical parameters considered were altered when clams were exposed to the highest concentration. The present findings further revealed that in the presence of sediment, clams mostly invested in non-enzymatic defenses (such as reduced glutathione, GSH), while animals exposed to GO in the absence of sediment favored their enzymatic antioxidant defense capacity (catalase, CAT and superoxide dismutase, SOD). This study highlights the relevance of environmental variations as key factors influencing organisms' responses to pollutants.

Insight into the effect of oxidation degree of graphene oxides on their removal from wastewater via froth flotation

The effect of oxidation degree of graphene oxides (GO) on their removal from wastewater via froth flotation was studied in this work. Four types of GO samples with different oxidation degrees were synthesized and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force spectroscopy (AFM) et al. The effects of cetyl trimethyl ammonium bromide (CTAB) concentration, pH, stirring time on the removal of GO by froth flotation had been discussed. It was found that the addition of CTAB could improve surface hydrophobicity of GO, endowing GO to be easily separated by froth flotation. The removal was dependent on CTAB dosage, pH and stirring time. Moreover, the removal first increased and then decreased with the increasing oxidation degree of GO, and less kinetic energy input was needed to overcome the energy barrier between GO flocs with the increase of oxidation degree. The removal mechanism was proven to be electrostatic attraction, and the different contents of oxgenous-containing functional groups in GOs with various oxidation degrees played a vital role in their removal via froth flotation.

Antimicrobial s-PBC Coatings for Innovative Multifunctional Water Filters

Biological contamination is a typical issue in water treatment. Highly concentrated microbial suspensions in a water flow may cause filter occlusion and biofilm formation, affecting the lifespan and quality of water purification systems and increasing the risk of nosocomial infections. In order to contrast the biofilm formation, most of the conventional strategies rely on the water chemical modification and/or on the use of filters functional coatings. The former is unsafe for huge chemicals spilling required; therefore, we focus on the second approach and we propose the use of a sulfonated pentablock copolymer (s-PBC, commercially named Nexar™) as innovative multifunctional coating for improving the performance of commercial water filters. S-PBC-coated polypropylene (PP) samples were tested against the pathogen Pseudomonas aeruginosa. The covering of PP with s-PBC results in a more hydrophilic, acid, and negatively charged surface. These properties avoid the adhesion and proliferation attempts of planktonic bacteria, i.e., the biofilm formation. Inhibition tests were performed on the as-modified filters and an evident antibacterial activity was observed. The results point out the possibility of using Nexar^TM as coating layer for filters with antifouling properties and a simultaneous ability to remove bacteria and cationic dyes from water.

Graphene-Like Layers from Carbon Black: In Vivo Toxicity Assessment

Graphene-like (GL) layers, a new graphene-related material (GRM), possess peculiar chemical, colloidal, optical and transport properties. Considering the very recent promising application of GL layers in biomedical and bioelectronic fields, it is of utmost importance to investigate the toxicological profile of these nanomaterials. This study represents an important first report of a complete in vivo toxicity assessment of GL layers on embryonic zebrafish (Danio rerio). Our results show that GL layers do not lead to any perturbations in the different biological parameters evaluated, indicating their good biocompatibility on a vertebrate model. The new insight into the biosafety of GL layers will expand their applications in nanomedicine.

The Impact on Antioxidant Enzyme Activity and Related Gene Expression Following Adult Zebrafish (Danio rerio) Exposure to Dimethyl Phthalate

Simple Summary

Dimethyl phthalate (DMP) is a widespread environmental contaminant and its toxicological effects on fish have not been adequately examined. Our present study clearly showed that a high concentration induced oxidative damage in zebrafish, which proved the molecular regulation due to the negative effects of DMP, along with the physical damage in zebrafish. We also found that antioxidant enzymes might be used as appropriate biochemical markers for the toxic identification of DMP.

Abstract

Dimethyl phthalate (DMP) is a widespread environmental contaminant that poses potential toxicity risks for animals and humans. However, the toxicological effects of DMP on fish have not been adequately examined. In this study, the acute toxicity, oxidative damage, antioxidant enzyme activities, and relative gene expression patterns were investigated in the liver of adult zebrafish (Danio rerio) exposed to DMP. We found that the lethal concentration (LC₅₀) of DMP for zebrafish after 96 h of exposure was 45.8 mg/L. The zebrafish that were exposed to low, medium and high concentrations of DMP (0.5, 4.6, and 22.9 mg/L, respectively) for 96 h had an increased malondialdehyde (MDA) content and a lower antioxidant capacity compared with the control solvent group. The total superoxide dismutase (SOD) activity was significantly higher than 0 h after initial exposure for 24 h at low concentrations, and then decreased at high concentrations after exposure for 96 h. The catalase (CAT) and glutathione S-transferase (GST) activities were significantly reduced after 96 h of exposure to high concentrations of DMP, with the up- or down-regulation of the related transcriptional expression. These findings indicated that DMP could cause physiological effects in zebrafish by disturbing the expression levels of antioxidant enzymes. These results might contribute to the identification of biomarkers to monitor phthalate pollution.

Toxicity assessment of nano-TiO2 in Apis mellifera L., 1758: histological and immunohistochemical assays

The aim of this study was to evaluate the toxicity of titanium dioxide nanoparticles (TiO₂ NPs) by short-term toxicity tests in Apis mellifera, considered an excellent bioindicator organism mainly due to its sensitivity. Bees have been exposed to several concentrations of TiO₂ NPs (1 × 10^-3 , 1 × 10^-4 , 1 × 10^-5 , 1 × 10^-6 mg/10 ml) for 10 days. Morphostructural and histological assays were done on gut and honey sac. The research of exposure biomarkers like metallothioneins 1 (MT1) and Heat Shock Protein 70 (HSP70) was performed to verify if a detoxification mechanism has been activated in the exposed animals. No histological alteration on the epithelium of the gut and honey sac were observed in exposed samples. A significant positivity for anti-MT1 antibody was observed only in the honey sac cells. A weak positivity for HSP70 was observed in both structures analyzed. In several studies have shown the non-toxicity of TiO₂ NPs on other model organisms, in our study, titanium dioxide nanoparticles was proven to be highly toxic at the highest concentration tested (100% of lethality to 1 × 10^-3 mg/10 ml) and moderately toxic at lower concentrations. Honey bees proved to be excellent models for study of NPs toxicity and for monitoring environment.

Exploring the mechanisms of graphene oxide behavioral and morphological changes in zebrafish

The presence of natural organic matter such as humic acid (HA) can influence the behavior of graphene oxide (GO) in the aquatic environment. In this study, zebrafish embryos were analyzed after 5 and 7 days of exposure to GO (100 mg L^-1) and HA (20 mg L^-1) alone or together. The results indicated that, regardless of the presence of HA, larvae exposed to GO for 5 days showed an increase in locomotor activity, reduction in the yolk sac size, and total length and inhibition of AChE activity, but there was no difference in enzyme expression. The statistical analysis indicated that the reductions in total larval length, yolk sac size, and AChE activity in larvae exposed to GO persisted in relation to the control group, but there was a recovery of these parameters in groups also exposed to HA. Larvae exposed to GO for 7 days did not show significant differences in locomotor activity, but the RT-PCR gene expression analysis evidenced an increase in the AChE expression. Since the embryos exposed to GO showed a reduction in overall length, they were submitted to confocal microscopy and their muscle tissue configuration investigated. No changes were observed in the muscle tissue. The results indicated that HA is associated with the toxicity risk modulation by GO and that some compensatory homeostasis mechanisms may be involved in the developmental effects observed in zebrafish.

Biomarkers of Exposure to Chemical Contamination in the Commercial Fish Species Lepidopus caudatus (Euphrasen, 1788): A Particular Focus on Plastic Additives

In recent years, the Mediterranean Sea has become an accumulation zone for waste generated by the 22 countries bordering its shores. Although the effects of plastic litter on the marine environment and on organisms have recently been studied in other areas, further information is needed for the Mediterranean Sea and, in particular, about plastics additives inputs and interactions with the biota and the trophic network, such as phthalates and bisphenol A. Plastic material production, use and disposal contribute also to the release of heavy metals into the environment, such as mercury (Hg), often used during the production of chlorine, the primary ingredient in PVC, lead (Pb) and cadmium (Cd), which are used as stabilizers in PVC and leach out of products during use and disposal. Our research aims to evaluate phthalates, bisphenol A and heavy metals contamination in Lepidopus caudatus (Pisces, Trichiuridae), which could be considered as a potential sentinel species. For the evaluation of toxicological effects, we evaluated the expression of vitellogenin and metallothioneins 1. In all samples analyzed, we have not found microplastics in the gastrointestinal tract but chemical analysis revealed the presence of high content of phthalates, and in particular high quantities of DIDP, DEHP, bis-benzylester phthalate, bis-butyl ester phthalate and mono-N-butyl ester phthalate in different organs. Instead, trace elements detected in tissue revealed a trend of concentrations generally higher in liver and intestine than gill and muscle tissues. Immunohistochemical analysis for anti-metallothionein 1 antibody showed a strong positivity of liver cells, both in females and males. Analysis for the anti-vitellogenin antibody showed in females a strong positivity both in the liver cells and in the gonads, in male specimens was found to be always negative except for a specimen, in which it was highlighted a positivity in some areas of the liver and of the gonad.

Ecotoxic impact assessment of graphene oxide on lipid peroxidation at mitochondrial level and redox modulation in fresh water fish Anabas testudineus

Rapidly expanding nanoparticle industries are predicted to have turnover of ∼$173.95 billion by 2025, indicating an urgency to study their comprehensive toxicological impact(s). Toxic effects of Graphene Oxide (GO) on oxidative stress physiology especially at mitochondrial level and redox modulation in fish in general and in climbing perch Anabas testudineus is absent. Therefore, we have investigated the toxic impacts of sub lethal doses of GO on selected oxidative stress physiology markers, protein and nucleic acid content along with haematological parameters in A. testudineus. Discriminant function and correlation analyses suggest that GO had toxic effects on the fish, as revealed from the studied parameters. Liver and gill tissues had shown strong response to GO than muscle. Augmented gradual accumulation of cellular lipid peroxides, specifically in mitochondria, was noticed. Activity of superoxide dismutase, catalase, and glutathione-S-transferase was augmented in contrast to the lowered level of the reduced glutathione titre. Alleviated total red blood corpuscle count and haemoglobin titre was parallel with an augmentation of white blood corpuscle count under GO administration. The protein level was also alleviated gradually in liver with clear changes in tissue specific nucleic acid levels, which was reduced under GO treatment. Results of the present study indicate that GO induces oxidative stress in cell and mitochondria in fish. Therefore, very careful future practices of use of GO directly, or as cargo in environmental monitoring processes in aquatic models in vitro in general and Pisces model in particular are suggested.

Graphene-Based Nanomaterials Toxicity in Fish

Due to their unique physicochemical properties, graphene-based nanoparticles (GPNs) constitute one of the most promising types of nanomaterials used in biomedical research. GPNs have been used as polymeric conduits for nerve regeneration and carriers for targeted drug delivery and in the treatment of cancer via photothermal therapy. Moreover, they have been used as tracers to study the distribution of bioactive compounds used in healthcare. Due to their extensive use, GPN released into the environment would probably pose a threat to living organisms and ultimately to human health. Their accumulation in the aquatic environment creates problems to aquatic habitats as well as to food chains. Until now the potential toxic effects of GPN are not properly understood. Despite agglomeration and long persistence in the environment, GPNs are able to cross the cellular barriers successfully, entered into the cells, and are able to interact with almost all the cellular sites including the plasma membrane, cytoplasmic organelles, and nucleus. Their interaction with DNA creates more potential threats to both the genome and epigenome. In this brief review, we focused on fish, mainly zebrafish (Danio rerio), as a potential target animal of GPN toxicity in the aquatic ecosystem.

Size dependent oxidative stress response of the gut of Daphnia magna to functionalized nanodiamond particles

Nanodiamonds are a type of engineered nanomaterial with high surface area that is highly tunable and are being proposed for use as a material for medical imaging or drug delivery to composites. With their potential for widespread use they may potentially be released into the aquatic environment as are many chemicals used for these purposes. It is generally thought that nanodiamonds are innocuous, but toxicity may occur due to surface functionalization. This study investigated the potential oxidative stress and antioxidant response of enterocytes in a freshwater invertebrate, Daphnia magna, a common aquatic invertebrate for ecotoxicological studies, in response to two types of functionalized nanodiamonds (polyallylamine and oxidized). We also examined how the size of the nanomaterial may influence toxicity by testing two different sizes (5 nm and 15 nm) of nanodiamonds with the same functionalization. Adults of Daphnia magna were exposed to three concentrations of each of the nanodiamonds for 24 h. We found that both 5 and 15 nm polyallylamine nanodiamond and oxidized nanodiamond induced the production of reactive oxygen species in tissues. The smaller 5 nm nanodiamond induced a significant change in the expression of heat shock protein 70 and glutathione-S-transferase. This may suggest that daphnids mounted an antioxidant response to the oxidative effects of 5 nm nanodiamonds but not the comparative 15 nm nanodiamonds with either surface chemistry. Outcomes of this study reveal that functionalized nanodiamond may cause oxidative stress and may potentially initiate lipid peroxidation of enterocyte cell membranes in freshwater organisms, but the impact of the exposure depends on the particle size.

The in vitro toxicity analysis of titanium dioxide (TiO2) nanoparticles on kinematics and biochemical quality of rainbow trout sperm cells

In recent years, titanium dioxide (TiO₂) nanoparticles (NPs) as metal oxide nanoparticles are widely used in industry, agriculture, personal care products, cosmetics, sun protection and toothpaste, electronics, foodstuffs and food packaging. This use of nano-TiO₂ has been associated with environmental toxicity concerns. Therefore, the aim of this study was to evaluate the in vitro effect of different doses of TiO₂ NPs (∼30-40 nm) (0.01, 0.1, 0.5, 1, 10 and 50 mg/L) at 4oC for 3 h on the sperm cell kinematics as velocities of Rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) sperm cells. Furthermore, oxidative stress markers (total glutathione (TGSH) and superoxide dismutase (SOD) were assessed in sperm cells after exposure to TiO₂ NPs. According to the obtained results, there were statistically significant (P < 0.05) decreasing in the velocities of sperm cells after 10 mg/L TiO₂ NPs and an increase the activity of SOD (P < 0.05) and TGSH levels were determined.

Cement-Induced Coagulation of Aqueous Graphene Oxide with Ultrahigh Capacity and High Rate Behavior

Graphene oxide (GO) has excellent physicochemical properties and is used in multiple areas. However, the potential toxicity and environmental problems associated with GO increase its risk to the ecological system. In this study, cement was employed as a coagulant to eliminate GO from aqueous solutions. The effects of the cement dosage, the contact time, and the concentration and volume of the aqueous GO solution on the GO coagulation capacity were investigated in detail. The results showed that the dosage of cement had a significant effect on the coagulation process, and coagulation equilibrium was achieved in less than 1 h. Compared to coagulants used to remove GO from water in other reports, cement exhibited an ultrahigh coagulation capacity of approximately 5981.2 mg/g with 0.4 mg/mL GO solution. The kinetic analysis showed that the GO removal behavior could be described by a pseudo second-order model. The in-depth mechanism of GO coagulation using cement included Ca²⁺-induced coagulation of GO and adsorption by the hydrated product of cement paste. The present study revealed that cement could be a very cheap and promising material for the efficient elimination of GO from aqueous solutions.

Ocular toxicity of reduced graphene oxide or graphene oxide exposure in mouse eyes

With the wide application and mass production of nanoparticle products, environmental nanopollutants will become increasingly common. The eye is an important organ responsible for vision in most living organisms, and it is directly exposed to the atmosphere. Direct contact between the eye and nanoparticles in the environment can potentially lead to ocular damage. However, publications focusing on the eye-damaging potential of nanoparticles are scarce. Therefore, to evaluate the impact of nanoparticles on the eyes, we investigated the ocular toxicity of reduced graphene oxide (RGO) and graphene oxide (GO) using morphological and molecular biological methods in vivo and in vitro in the present work. The findings show that short-term repeated GO exposure can cause obvious intraocular inflammation, an incrassated corneal stromal layer, cell apoptosis in the cornea, iris neovascularization and significant cytotoxicity of rat corneal epithelial cells (rCECs), while RGO causes no significant ocular toxicity in mice.

Exposure to Alumina Nanoparticles in Female Mice During Pregnancy Induces Neurodevelopmental Toxicity in the Offspring

Alumina nanoparticles (AlNP) have been shown to accumulate in organs and penetrate biological barriers which lead to toxic effects in many organ systems. However, it is not known whether AlNP exposure to female mice during pregnancy can affect the development of the central nervous system or induce neurodevelopmental toxicity in the offspring. The present study aims to examine the effect of AlNP on neurodevelopment and associated underlying mechanism. ICR strain adult female mice were randomly divided into four groups, which were treated with normal saline (control), 10 μm particle size of alumina (bulk-Al), and 50 and 13 nm AlNP during entire pregnancy period. Aluminum contents in the hippocampus of newborns were measured and neurodevelopmental behaviors were tracked in the offspring from birth to 1 month of age. Furthermore, oxidative stress and neurotransmitter levels were measured in the cerebral cortex of the adolescents. Our results showed that aluminum contents in the hippocampus of newborns in AlNP-treated groups were significantly higher than those in bulk-Al and controls. Moreover, the offspring delivered by AlNP-treated female mice displayed stunted neurodevelopmental behaviors. Finally, the offspring of AlNP-treated mice demonstrated significantly increased anxiety-like behavior with impaired learning and memory performance at 1 month of age. The underlying mechanism could be related to increased oxidative stress and decreased neurotransmitter levels in the cerebral cortex. We therefore conclude that AlNP exposure of female mice during pregnancy can induce neurodevelopmental toxicity in offspring.