Silver nanoparticles affect the neural development of zebrafish embryos

Nervous system exposure of different classes of nanoparticles: A review on potential toxicity and mechanistic studies

Nanoparticles (NPs) are generally defined as very small particles in the size range of 1-100 nm. Due to the rapid development of modern society, many new materials have been developed. The widespread use of NPs in medical applications, the food industry and the textile industry has led to an increase in NPs in the environment and the possibility of human contact, which poses a serious threat to human health. The nervous system plays a leading role in maintaining the integrity and unity of the body and maintaining a harmonious balance with the external environment. Therefore, based on two categories of organic and inorganic NPs, this paper systematically summarizes the toxic effects and mechanisms of NPs released into the nervous system. The results showed that exposure to NPs may damage the nervous system, decrease learning and cognitive ability, and affect embryonic development. Finally, a remediation scheme for NPs entering the body via the environment is also introduced. This scheme aims to reduce the neurotoxicity caused by NPs by supplementing NPs with a combination of antioxidant and anti-inflammatory compounds. The results provide a valuable reference for future research in this field.

Developmental impacts and toxicological hallmarks of silver nanoparticles across diverse biological models

Silver nanoparticles (AgNPs), revered for their antimicrobial prowess, have become ubiquitous in a range of products, from biomedical equipment to food packaging. However, amidst their rising popularity, concerns loom over their possible detrimental effects on fetal development and subsequent adult life. This review delves into the developmental toxicity of AgNPs across diverse models, from aquatic species like zebrafish and catfish to mammalian rodents and in vitro embryonic stem cells. Our focus encompasses the fate of AgNPs in different contexts, elucidating associated hazardous results such as embryotoxicity and adverse pregnancy outcomes. Furthermore, we scrutinize the enduring adverse impacts on offspring, spanning impaired neurobehavior function, reproductive disorders, cardiopulmonary lesions, and hepatotoxicity. Key hallmarks of developmental harm are identified, encompassing redox imbalances, inflammatory cascades, DNA damage, and mitochondrial stress. Notably, we explore potential explanations, linking immunoregulatory dysfunction and disrupted epigenetic modifications to AgNPs-induced developmental failures. Despite substantial progress, our understanding of the developmental risks posed by AgNPs remains incomplete, underscoring the urgency of further research in this critical area.

Acidified water promotes silver-induced toxicity in zebrafish embryos

Freshwater acidification is a global environmental challenge, yet the effects of acidic water on fish resistance to toxic Ag+ remain an unexplored area. To address this knowledge gap, zebrafish embryos were exposed to different concentrations (0 (control), 0.1, and 0.25 mg/L) of AgNO3 under pH 5 or 7 for 7 days. Notably, AgNO3 at 0.25 mg/L resulted in 100 % mortality in both pH conditions, while AgNO3 at 0.1 mg/L resulted in higher mortality at pH 5 (85 %) compared to pH 7 (20 %), indicating that acidic water enhanced Ag+ toxicity. Several parameters, including body length, inner ear (otic vesicle and otolith) and yolk sac areas, lateral line hair cell number and morphology, the number of ionocytes (H+-ATP-rich cells and Na+/K+-ATP-rich cells), and ion contents (Ag+, Na+, and Ca2+) were assessed at 96 h (day 4) to investigate individual and combined effects of Ag+ and acid on embryos. Acid alone did not significantly alter most parameters, but it decreased the yolk sac area and increased the ionocyte number. Conversely, Ag+ alone caused reductions in most parameters, including body length, the inner ear area, hair cell number, and ionocyte number. Combining acid and Ag+ resulted in greater suppression of the otolith area, hair cell number, and Na+/Ca2+ contents. In conclusion, acidification of freshwater poses a potential risk to fish embryo viability by increasing their susceptibility to silver toxicity, specifically affecting sensory function and ion regulation.

Progress in characterizing ABC multidrug transporters in zebrafish

Zebrafish have proved to be invaluable for modeling complex physiological processes shared by all vertebrate animals. Resistance of cancers and other diseases to drug treatment can occur owing to expression of the ATP-dependent multidrug transporters ABCB1, ABCG2, and ABCC1, either because of expression of these transporters by the target cells to reduce intracellular concentrations of cytotoxic drugs at barrier sites such as the blood-brain barrier (BBB) to limit penetration of drugs into privileged compartments, or by affecting the absorption, distribution, and excretion of drugs administered orally, through the skin, or directly into the bloodstream. We describe the drug specificity, cellular localization, and function of zebrafish orthologs of multidrug resistance ABC transporters with the goal of developing zebrafish models to explore the physiological and pathophysiological functions of these transporters. Finally, we provide context demonstrating the utility of zebrafish in studying cancer drug resistance. Our ultimate goal is to improve treatment of cancer and other diseases which are affected by ABC multidrug resistance transporters.

Toxic effects of polystyrene nanoparticles on the development, escape locomotion, and lateral-line sensory function of zebrafish embryos

Environmental pollution by micro- and nanosized plastic particles is a potential threat to aquatic animals. Polystyrene is one of the most common plastic particles in aquatic environments. Previous studies found that polystyrene nanoparticles (PNs) can penetrate the integument and accumulate in the organs of fish embryos. However, the potential impacts of PNs on fish embryos are not fully understood. To investigate this issue, zebrafish embryos were exposed to different concentrations (10, 25, and 50 mg/L) of PNs (25 nm) for 96 h (4-100 h post-fertilization), and various endpoints were examined, including developmental morphology (body length, sizes of the eyes, otic vesicles, otoliths, pericardial cavity, and yolk sac), locomotion (touch-evoked escape response and spinal motor neurons), and lateral-line function (hair cell number and hair bundle number). Exposure to 50 mg/L of PNs resulted in significant adverse effects across all endpoints studied, indicating that embryonic development was severely disrupted, and both locomotion and sensory function were impaired. However, at 25 mg/L of PNs, only locomotion and sensory function were significantly affected. The effects were insignificant in all examined endpoints at 10 mg/L of PNs. Transcript levels of several marker genes for neuronal function and eye development were suppressed after treatment. Exposure to fluorescent PNs showed that they accumulated in various organs including, the eyes, gills, blood vessels, gallbladder, gut, and lateral line neuromasts. Overall, this study suggests that short-term exposure to a high concentration of PNs can threaten fish survival by impairing embryonic development, locomotion performance, and mechanical sensory function.

Comparison of toxicity of silver nanomaterials and silver nitrate on developing zebrafish embryos: Bioavailability, osmoregulatory and oxidative stress

The mechanisms of toxicity of engineered nanomaterials (ENMs) to the early life stages of freshwater fish, and the relative hazard compared to dissolved metals, is only partially understood. In the present study, zebrafish (Danio rerio) embryos were exposed to lethal concentrations of silver nitrate (AgNO₃) or silver (Ag) ENMs (primary size 42.5 ± 10.2 nm). The 96 h-LC₅₀ for AgNO₃ was 32.8 ± 0.72 μg Ag L^-1 (mean ± 95% CI) compared to 6.5 ± 0.4 mg L^-1 of the whole material for Ag ENMs; with the ENMs being orders of magnitude less toxic than the metal salt. The EC₅₀ for hatching success was 30.5 ± 1.4 μg Ag L^-1 and 6.04 ± 0.4 mg L^-1 for AgNO₃ and Ag ENMs, respectively. Further sub-lethal exposures were performed with the estimated LC₁₀ concentrations for both AgNO₃ or Ag ENMs over 96 h where about 3.7% of the total Ag as AgNO₃ was internalised, as measured by Ag accumulation in the dechorionated embryos. However, for the ENMs exposures, nearly all (99.8%) of the total Ag was associated with chorion; indicating the chorion as an effective barrier to protect the embryo in the short term. Calcium (Ca²⁺) and sodium (Na⁺) depletion was induced in embryos by both forms of Ag, but hyponatremia was more pronounced in the nano form. Total glutathione (tGSH) levels declined in embryos exposed to both Ag forms, but a superior depletion occurred with the nano form. Nevertheless, oxidative stress was mild as superoxide dismutase (SOD) activity stayed uniform and the sodium pump (Na⁺/K⁺-ATPase) activity had no appreciable inhibition compared to the control. In conclusion, AgNO₃ was more toxic to the early life stage zebrafish than the Ag ENMs, still differences were found in the exposure and toxic mechanisms of both Ag forms.

Inhibition of the NF-κB signaling pathway affects gonadal differentiation and leads to male bias in Paramisgurnus dabryanus

In recent years, sex-controlled breeding has emerged as an effective strategy to enhance the yields of economic animals with different growth characteristics, while increasing the economic benefits of aquaculture. It is known that the NF-κB pathway participates in gonadal differentiation and reproduction. Therefore, we used the large-scale loach as a research model for the present study and selected an effective inhibitor of the NF-κB signaling pathway (QNZ). This, to investigates the impacts of the NF-κB signaling pathway on gonadal differentiation during a critical period of gonad development and after maturation. Simultaneously, the sex ratio bias and the reproductive capacities of adult fish were analyzed. Our results indicated that the inhibition of the NF-κB signaling pathway influenced the expression of genes related to gonad development, regulated the gene expression related to the brain-gonad-liver axis of juvenile loaches, and finally impacted the gonadal differentiation of the large-scale loach and promoted a male-biased sex ratio. Meanwhile, high QNZ concentrations affected the reproductive abilities of adult loaches and inhibited the growth performance of offspring. Thus, our results deepened the exploration of sex control in fish and provided a certain research basis for the sustainable development of the aquaculture industry.

Silver Nanoparticles Cause Neural and Vascular Disruption by Affecting Key Neuroactive Ligand-Receptor Interaction and VEGF Signaling Pathways

Introduction

Silver nanoparticles (AgNP) are widely used as coating materials. However, the potential risks of AgNP to human health, especially for neural and vascular systems, are still poorly understood.

Methods

The vascular and neurotoxicity of various concentrations of AgNP in zebrafish were examined using fluorescence microscopy. In addition, Illumina high-throughput global transcriptome analysis was performed to explore the transcriptome profiles of zebrafish embryos after exposure to AgNP. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted to elucidate the top 3000 differentially expressed genes (DEGs) between AgNP-exposed and control groups.

Results

We systematically investigated the neural and vascular developmental toxicities of AgNP exposure in zebrafish. The results demonstrated that AgNP exposure could cause neurodevelopmental anomalies, including a small-eye phenotype, neuronal morphology defects, and inhibition of athletic abilities. In addition, we found that AgNP exposure induces angiogenesis malformation in zebrafish embryos. Further RNA-seq revealed that DEGs were mainly enriched in the neuroactive ligand-receptor interaction and vascular endothelial growth factor (Vegf) signaling pathways in AgNP-treated zebrafish embryos. Specifically, the mRNA levels of the neuroactive ligand-receptor interaction pathway and Vegf signaling pathway-related genes, including si:ch73-55i23.1, nfatc2a, prkcg, si:ch211-132p1.2, lepa, mchr1b, pla2g4aa, rac1b, p2ry6, adrb2, chrnb1, and chrm1b, were significantly regulated in AgNP-treated zebrafish embryos.

Conclusion

Our findings indicate that AgNP exposure transcriptionally induces developmental toxicity in neural and vascular development by disturbing neuroactive ligand-receptor interactions and the Vegf signaling pathway in zebrafish embryos.

Fish to learn: insights into the effects of environmental chemicals on eye development and visual function in zebrafish

Vision is the most essential sense system for the human being. Congenital visual impairment affects millions of people globally. It is increasingly realized that visual system development is an impressionable target of environmental chemicals. However, due to inaccessibility and ethical issues, the use of humans and other placental mammals is constrained, which limits our better understanding of environmental factors on ocular development and visual function in the embryonic stage. Therefore, as complementing laboratory rodents, zebrafish has been the most frequently employed to understand the effects of environmental chemicals on eye development and visual function. One of the major reasons for the increasing use of zebrafish is their polychromatic vision. Zebrafish retinas are morphologically and functionally analogous to those of mammalian, as well as evolutionary conservation among vertebrate eye. This review provides an update on harmful effects from exposure to environmental chemicals, involving metallic elements (ions), metal-derived nanoparticles, microplastics, nanoplastics, persistent organic pollutants, pesticides, and pharmaceutical pollutants on the eye development and visual function in zebrafish embryos. The collected data provide a comprehensive understanding of environmental factors on ocular development and visual function. This report highlights that zebrafish is promising as a model to identify hazardous toxicants toward eye development and is hopeful for developing preventative or postnatal therapies for human congenital visual impairment.

Emerging Trends in Advanced Translational Applications of Silver Nanoparticles: A Progressing Dawn of Nanotechnology

Nanoscience has emerged as a fascinating field of science, with its implementation in multiple applications in the form of nanotechnology. Nanotechnology has recently been more impactful in diverse sectors such as the pharmaceutical industry, agriculture sector, and food market. The peculiar properties which make nanoparticles as an asset are their large surface area and their size, which ranges between 1 and 100 nanometers (nm). Various technologies, such as chemical and biological processes, are being used to synthesize nanoparticles. The green chemistry route has become extremely popular due to its use in the synthesis of nanoparticles. Nanomaterials are versatile and impactful in different day to day applications, resulting in their increased utilization and distribution in human cells, tissues, and organs. Owing to the deployment of nanoparticles at a high demand, the need to produce nanoparticles has raised concerns regarding environmentally friendly processes. These processes are meant to produce nanomaterials with improved physiochemical properties that can have significant uses in the fields of medicine, physics, and biochemistry. Among a plethora of nanomaterials, silver nanoparticles have emerged as the most investigated and used nanoparticle. Silver nanoparticles (AgNPs) have become vital entities of study due to their distinctive properties which the scientific society aims to investigate the uses of. The current review addresses the modern expansion of AgNP synthesis, characterization, and mechanism, as well as global applications of AgNPs and their limitations.

ZIF-8 nanoparticles induce neurobehavioral disorders through the regulation of ROS-mediated oxidative stress in zebrafish embryos

Zeolite imidazolate framework-8 (ZIF-8) is a nanomaterial of metal-organic frameworks (MOFs), which have various applications in drug delivery and water pollution remediation. However, little is known about its developmental neurotoxicity in aquatic organisms, especially on the low-level exposure. In the present study, we investigated the toxic effects of ZIF-8 NPs on the neuron development, behavioral traits, oxidative stress and gene expression in zebrafish embryos. Firstly, our results showed that ZIF-8 induced significantly embryonic malformations and abnormal development of nervous system in zebrafish embryos with a concentration-dependent manner. Meanwhile, the locomotor behavior was obviously inhibited while the anxiety behavior was greatly increased after ZIF-8 exposure. Secondly, the levels of ROS and antioxidant enzyme activities (CAT, SOD and MDA) together with AChE and ATPase were substantially increased in the ZIF-8 exposed groups. At the molecular level, ZIF-8 NPs could down-regulate the expression profiles of neural development-related genes (gap43, synapsin 2a and neurogenin 1) and PD-like related genes (dj-1, dynactin and parkin), but up-regulate the expression levels of neuro-inflammatory genes (nox-1, glip1a and glip1b) in larval zebrafish. In addition, we further explored the molecular mechanism of neurotoxicity induced by ZIF-8 with pharmacological experiments. The results showed that specific inhibition of ROS-mediated oxidative stress by the astaxanthin could reverse the expression patterns of ATPase, AChE and neurodevelopmental genes. Moreover, astaxanthin can partially rescue the ZIF-8-modulated locomotor behavior. Taken together, our results demonstrated that ZIF-8 had the potential to cause neurotoxicity in zebrafish embryos. These informations presented in this study will help to elucidate the molecular mechanisms of ZIF-8 nanoparticles exposure in zebrafish, which providing a scientific evaluation of its safety to aquatic ecosystems.

High throughput embryonic zebrafish test with automated dechorionation to evaluate nanomaterial toxicity

Engineered nanomaterials pose occupational health and environmental concerns as they possess unique physical and chemical properties that can contribute to toxicity. High throughput toxicity screening methods are needed to address the increasing number of nanomaterials in production. Here we used a zebrafish photomotor response (PMR) test to evaluate a set of fifteen nanomaterials with military relevance. Automated dechorionation of zebrafish embryos was used to enhance nanomaterials bioavailability. Optimal PMR activity in zebrafish embryos was found at 30–31 hours post-fertilization (hpf). Behavioral and toxicological responses were measured at 30 and 120 hpf; behavioral responses were found for thirteen of the fifteen nanomaterials and acute toxicity (LC50) levels for nine of the fifteen nanomaterials below the maximum test concentration of 500 μg/ml. Physico-chemical characterization of the nanomaterials detected endotoxin and bacterial contamination in two of the tested samples, which may have contributed to observed toxicity and reinforces the need for physical and chemical characterization of nanomaterials use in toxicity testing. The zebrafish PMR test, together with automated dechorionation, provides an initial rapid assessment of the behavioral effects and toxicity of engineered nanomaterials that can be followed up by physico-chemical characterization if toxicity is detected, reducing the amount of time and monetary constraints of physico-chemical testing.

Neurotoxicity of nanoparticles: Insight from studies in zebrafish

Nanoparticles are widely used in industry and personal care, and they inevitably end up in people's bodies and the environment. The widespread use of nanoparticles has raised new concerns about their neurotoxicity, as nanoparticles can enter the nervous system by blood-brain barrier. In neurotoxicity testing, the zebrafish provides powerful tools to overcome the limitations of other models. This paper will provide a comprehensive review of the power of zebrafish in neurotoxicity tests and the neurotoxic effects of nanoparticles, including inorganic, organic, and metal-based nanoparticles, on zebrafish from different perspectives. Such information can be used to predict not only the effects of nanoparticles on other species exposed to the aquatic environment but also the neurotoxicity of nanoparticles in humans.

Developmental neurotoxicity of silver nanoparticles: the current state of knowledge and future directions

The increasing production and use of silver nanoparticles (AgNPs) as an antimicrobial agent in an array of medical and commercial products, including those designed for infants and children, poses a substantial risk of exposure during the developmental period. This review summarizes current knowledge on developmental neurotoxicity of AgNPs in both pre- and post-natal stages with a focus on the biological specificity of immature organisms that predisposes them to neurotoxic insults as well as the molecular mechanisms underlying AgNP-induced neurotoxicity. The current review revealed that AgNPs increase the permeability of the blood-brain barrier (BBB) and selectively damage neurons in the brain of immature rats exposed pre and postnatally. Among the AgNP-induced molecular mechanisms underlying toxic insult is cellular stress, which can consequently lead to cell death. Glutamatergic neurons and NMDAR-mediated neurotransmission also appear to be a target for AgNPs during the postnatal period of exposure. Collected data indicate also that our current knowledge of the impact of AgNPs on the developing nervous system remains insufficient and further studies are required during different stages of development with investigation of environmentally-relevant doses of exposure.

Does Nanosilver Have a Pronounced Toxic Effect on Humans?

Due to the development of high-tech industries, the modern world is characterized by the increased production and consumption of nanoparticles (NPs) and nanomaterials. Among produced metal nanoparticles, silver nanoparticles are widely used in everyday life products, cosmetics, and medicine. It has already been established that, in nanoscale form, many even inert materials become toxic. Therefore, the study of the toxicity of various substances in nanoscale form is an urgent scientific task. There is now a body of experience on the toxic effect of AgNPs. In the present review, the most well-known results obtained over the 2009–2021 period, including the own performance on the toxicity of silver NPs, are collected and analyzed. Along with the data reporting a certain level of toxicity of silver NPs, experiments that did not reveal any obvious toxicity of nanosized forms of silver are discussed. According to the performed studies, the toxicity of silver NPs is often caused not by NPs themselves but by silver ions, compounds used for nanoparticle stabilization, and other reasons. Based on the analysis of the collected data, it can be concluded that at actual levels of silver NPs used in everyday life, workplace, and medicine, they will not have strong toxic effects on a healthy adult body.

Building the Bridge From Aquatic Nanotoxicology to Safety by Design Silver Nanoparticles

Nanotechnologies have rapidly grown, and they are considered the new industrial revolution. However, the augmented production and wide applications of engineered nanomaterials (ENMs) and nanoparticles (NPs) inevitably lead to environmental exposure with consequences on human and environmental health. Engineered nanomaterial and nanoparticle (ENM/P) effects on humans and the environment are complex and largely depend on the interplay between their peculiar properties such as size, shape, coating, surface charge, and degree of agglomeration or aggregation and those of the receiving media/body. These rebounds on ENM/P safety and newly developed concepts such as the safety by design are gaining importance in the field of sustainable nanotechnologies. This article aims to review the critical characteristics of the ENM/Ps that need to be addressed in the safe by design process to develop ENM/Ps with the ablility to reduce/minimize any potential toxicological risks for living beings associated with their exposure. Specifically, we focused on silver nanoparticles (AgNPs) due to an increasing number of nanoproducts containing AgNPs, as well as an increasing knowledge about these nanomaterials (NMs) and their effects. We review the ecotoxicological effects documented on freshwater and marine species that demonstrate the importance of the relationship between the ENM/P design and their biological outcomes in terms of environmental safety.

Differential effects of silver nanoparticles on two types of mitochondrion-rich ionocytes in zebrafish embryos

Silver nanoparticles (AgNPs) are increasingly used in our daily life and have become a potential environmental hazard. However, the toxic effects of AgNPs on the early stages of fish are not fully understood, and little is known about their effects on specific types of ionocytes. Using zebrafish embryos as a model, this study examined the effects (changes in cell number, morphology, NH₄⁺ secretion and gene expression) of sublethal concentrations of AgNPs (0.1, 1, and 3 mg/L) on two major types of ionocytes: H⁺ pump-rich (HR) ionocytes, and Na⁺ pump-rich (NaR) ionocytes in the skin of embryos. After exposure to AgNPs for 96 h, the number of HR ionocytes significantly declined by 30% and 41% in the 1 and 3 mg/L AgNP groups, respectively. In addition, the apical opening of HR ionocytes became smaller, suggesting that AgNPs impaired the critical structure for ion transport. NH₄⁺ secretion by HR ionocytes of embryos also declined significantly after AgNP exposure. In contrast, the number of NaR ionocytes increased by 29% and 43% in the 1 and 3 mg/L AgNP groups, respectively, while these cells deformed their shape. AgNPs altered mRNA levels of several ion channel and transporter genes involved in the functions of HR ionocytes and NaR ionocytes, and influenced hormone genes involved in regulating calcium homeostasis. This study shows that AgNPs can cause differential adverse effects on two types of ionocytes and the effects can threaten fish survival.

A review of the effects of metallic nanoparticles on fish

Many important discoveries have been made in the field of nanotechnology in the last 40 years. Since then, nanoparticles became nearly ubiquitous. With their spreading use, safety concerns have warranted extensive research of nanotoxicity. This paper offers information about the occurrence, transport, and behaviour of metallic nanoparticles in the aquatic environment. It further summarizes details about parameters that dictate the toxicity of nanoparticles and discusses the general/common mechanisms of their toxicity. This review also focuses on fish exposure to nanoparticles, including the possibility of trophic transport through the food chain. Information on some of the most frequently used metallic nanoparticles, such as silver, gold, and titanium dioxide, is further elaborated on.

Zebrafish Models for the Safety and Therapeutic Testing of Nanoparticles with a Focus on Macrophages

New nanoparticles and biomaterials are increasingly being used in biomedical research for drug delivery, diagnostic applications, or vaccines, and they are also present in numerous commercial products, in the environment and workplaces. Thus, the evaluation of the safety and possible therapeutic application of these nanomaterials has become of foremost importance for the proper progress of nanotechnology. Due to economical and ethical issues, in vitro and in vivo methods are encouraged for the testing of new compounds and/or nanoparticles, however in vivo models are still needed. In this scenario, zebrafish (Danio rerio) has demonstrated potential for toxicological and pharmacological screenings. Zebrafish presents an innate immune system, from early developmental stages, with conserved macrophage phenotypes and functions with respect to humans. This fact, combined with the transparency of zebrafish, the availability of models with fluorescently labelled macrophages, as well as a broad variety of disease models offers great possibilities for the testing of new nanoparticles. Thus, with a particular focus on macrophage-nanoparticle interaction in vivo, here, we review the studies using zebrafish for toxicological and biodistribution testing of nanoparticles, and also the possibilities for their preclinical evaluation in various diseases, including cancer and autoimmune, neuroinflammatory, and infectious diseases.

Toxicological Profile of Plasmonic Nanoparticles in Zebrafish Model

Plasmonic nanoparticles are increasingly employed in several fields, thanks to their unique, promising properties. In particular, these particles exhibit a surface plasmon resonance combined with outstanding absorption and scattering properties. They are also easy to synthesize and functionalize, making them ideal for nanotechnology applications. However, the physicochemical properties of these nanoparticles can make them potentially toxic, even if their bulk metallic forms are almost inert. In this review, we aim to provide a more comprehensive understanding of the potential adverse effects of plasmonic nanoparticles in zebrafish (Danio rerio) during both development and adulthood, focusing our attention on the most common materials used, i.e., gold and silver.

Silver Nanoparticles Stable to Oxidation and Silver Ion Release Show Size-Dependent Toxicity In Vivo

Silver nanoparticles (AgNPs) are widely used in commerce, however, the effect of their physicochemical properties on toxicity remains debatable because of the confounding presence of Ag+ ions. Thus, we designed a series of AgNPs that are stable to surface oxidation and Ag+ ion release. AgNPs were coated with a hybrid lipid membrane comprised of L-phosphatidylcholine (PC), sodium oleate (SOA), and a stoichiometric amount of hexanethiol (HT) to produce oxidant-resistant AgNPs, Ag-SOA-PC-HT. The stability of 7-month aged, 20-100 nm Ag-SOA-PC-HT NPs were assessed using UV-Vis, dynamic light scattering (DLS), and inductively coupled plasma mass spectrometry (ICP-MS), while the toxicity of the nanomaterials was assessed using a well-established, 5-day embryonic zebrafish assay at concentrations ranging from 0-12 mg/L. There was no change in the size of the AgNPs from freshly made samples or 7-month aged samples and minimal Ag+ ion release (<0.2%) in fishwater (FW) up to seven days. Toxicity studies revealed AgNP size- and concentration-dependent effects. Increased mortality and sublethal morphological abnormalities were observed at higher concentrations with smaller nanoparticle sizes. This study, for the first time, determined the effect of AgNP size on toxicity in the absence of Ag+ ions as a confounding variable.

Nanotoxicity of 2D Molybdenum Disulfide, MoS2, Nanosheets on Beneficial Soil Bacteria, Bacillus cereus and Pseudomonas aeruginosa

Concerns arising from accidental and occasional releases of novel industrial nanomaterials to the environment and waterbodies are rapidly increasing as the production and utilization levels of nanomaterials increase every day. In particular, two-dimensional nanosheets are one of the most significant emerging classes of nanomaterials used or considered for use in numerous applications and devices. This study deals with the interactions between 2D molybdenum disulfide (MoS2) nanosheets and beneficial soil bacteria. It was found that the log-reduction in the survival of Gram-positive Bacillus cereus was 2.8 (99.83%) and 4.9 (99.9988%) upon exposure to 16.0 mg/mL bulk MoS2 (macroscale) and 2D MoS2 nanosheets (nanoscale), respectively. For the case of Gram-negative Pseudomonas aeruginosa, the log-reduction values in bacterial survival were 1.9 (98.60%) and 5.4 (99.9996%) for the same concentration of bulk MoS2 and MoS2 nanosheets, respectively. Based on these findings, it is important to consider the potential toxicity of MoS2 nanosheets on beneficial soil bacteria responsible for nitrate reduction and nitrogen fixation, soil formation, decomposition of dead and decayed natural materials, and transformation of toxic compounds into nontoxic compounds to adequately assess the environmental impact of 2D nanosheets and nanomaterials.

Developmental exposure to silver nanoparticles leads to long term gut dysbiosis and neurobehavioral alterations

Due to their antimicrobial properties, silver nanoparticles (AgNPs) are used in a wide range of consumer products that includes topical wound dressings, coatings for biomedical devices, and food-packaging to extend the shelf-life. Despite their beneficial antimicrobial effects, developmental exposure to such AgNPs may lead to gut dysbiosis and long-term health consequences in exposed offspring. AgNPs can cross the placenta and blood–brain-barrier to translocate in the brain of offspring. The underlying hypothesis tested in the current study was that developmental exposure of male and female mice to AgNPs disrupts the microbiome–gut–brain axis. To examine for such effects, C57BL6 female mice were exposed orally to AgNPs at a dose of 3 mg/kg BW or vehicle control 2 weeks prior to breeding and throughout gestation. Male and female offspring were tested in various mazes that measure different behavioral domains, and the gut microbial profiles were surveyed from 30 through 120 days of age. Our study results suggest that developmental exposure results in increased likelihood of engaging in repetitive behaviors and reductions in resident microglial cells. Echo-MRI results indicate increased body fat in offspring exposed to AgNPs exhibit. Coprobacillus spp., Mucispirillum spp., and Bifidobacterium spp. were reduced, while Prevotella spp., Bacillus spp., Planococcaceae, Staphylococcus spp., Enterococcus spp., and Ruminococcus spp. were increased in those developmentally exposed to NPs. These bacterial changes were linked to behavioral and metabolic alterations. In conclusion, developmental exposure of AgNPs results in long term gut dysbiosis, body fat increase and neurobehavioral alterations in offspring.

Nanoparticles induced embryo-fetal toxicity

Applications of nanomaterials cause a general concern on their toxicity when they intentionally (such as in medicine) or unintentionally (environment exposure) enter into the human body. As a special subpopulation, pregnant women are more susceptible to nanoparticle (NP)-induced toxicity. More importantly, prenatal exposures may affect the entire life of the fetus. Through blood circulation, NPs may cross placental barriers and enter into fetus. A cascade of events, such as damage in placental barriers, generation of oxidative stress, inflammation, and altered gene expression, may induce delayed or abnormal fetal development. The physicochemical properties of NPs, exposure time, and other factors directly affect nanotoxicity in pregnant populations. Even though results from animal studies cannot directly extrapolate to humans, compelling evidence has already shown that, for pregnant women, caution must be taken when dealing with nanomedicines or NP pollutants.

Parental exposure to polystyrene microplastics at environmentally relevant concentrations has negligible transgenerational effects on zebrafish (Danio rerio)

Waterborne exposure to highly persistent microplastic pollutants is a major concern for aquatic species worldwide. There are still gaps in knowledge on microplastics' potential transgenerational effects on offspring generation. Using zebrafish, this study investigated the survival and early development of offspring through a 21-day continuous parental treatment with polystyrene microplastics. The results showed that continuous waterborne exposure to high concentrations (>100 μg/L) of polystyrene microplastics (1 μm) for 21 days resulted in notable microplastic accumulation in adult fish intestines. Exposure at microplastic concentrations greater than 100 μg/L also induced significant changes in steroidogenic mRNA expression in zebrafish gonads. However, no significant changes in the cumulative number of eggs spawned and fertilization rate were observed at any parental exposure concentrations when compared to the control. Early development of derived offspring, in terms of hatching rate, body length, malformation rate and mortality rate, did not significantly differ from that of the control. This study showed that transgenerational effects of parental exposure to polystyrene microplastics in zebrafish might be negligible or recoverable. This study provided new results and insights on the transgenerational effects of microplastics on a freshwater fish species and can help to understand impacts of microplastics on freshwater ecosystems.

Neurotoxic effects in zebrafish embryos by valproic acid and nine of its analogues: the fish-mouse connection?

Since teratogenicity testing in mammals is a particular challenge from an animal welfare perspective, there is a great need for the development of alternative test systems. In this context, the zebrafish (Danio rerio) embryo has received increasing attention as a non-protected embryonic vertebrate in vivo model. The predictive power of zebrafish embryos for general vertebrate teratogenicity strongly depends on the correlation between fish and mammals with respect to both overall general toxicity and more specific endpoints indicative of certain modes-of-action. The present study was designed to analyze the correlation between (1) effects of valproic acid and nine of its analogues in zebrafish embryos and (2) their known neurodevelopmental effects in mice. To this end, zebrafish embryos exposed for 120 h in an extended version of the acute fish embryo toxicity test (FET; OECD TG 236) were analyzed with respect to an extended list of sublethal endpoints. Particular care was given to endpoints putatively related to neurodevelopmental toxicity, namely jitter/tremor, deformation of sensory organs (eyes) and craniofacial deformation, which might correlate to neural tube defects caused by valproic acid in mammals. A standard evaluation of lethal (LC according to OECD TG 236) and sublethal toxicity (EC) merely indicated that four out of ten compounds tested in zebrafish correlate with positive results in mouse in vivo studies. A detailed assessment of more specific effects, however, namely, jitter/tremor, small eyes and craniofacial deformation, resulted in a correspondence of 75% with in vivo mouse data. A refinement of endpoint analysis from an integration of all observations into one LC_x or EC_x data (as foreseen by current ecotoxicology-driven OECD guidelines) to a differential evaluation of endpoints specific of selected modes-of-action thus increases significantly the predictive power of the zebrafish embryo model for mammalian teratogenicity. However, for some of the endpoints observed, e.g., scoliosis, lordosis, pectoral fin deformation and lack of movement, further experiments are required for the identification of underlying modes-of-action and an unambiguous interpretation of their predictive power for mammalian toxicity.

Species-Specific in vitro and in vivo Evaluation of Toxicity of Silver Nanoparticles Stabilized with Gum Arabic Protein

Introduction

We report, herein, in vitro, and in vivo toxicity evaluation of silver nanoparticles stabilized with gum arabic protein (AgNP-GP) in Daphnia similis, Danio rerio embryos and in Sprague Dawley rats.

Purpose

The objective of this investigation was to evaluate in vitro and in vivo toxicity of silver nanoparticles stabilized with gum arabic protein (AgNP-GP), in multispecies due to the recognition that toxicity evaluations beyond a single species reflect the environmental realism. In the present study, AgNP-GP was synthesized through the reduction of silver salt using the tri-alanine-phosphine peptide (commonly referred to as “Katti Peptide”) and stabilized using gum arabic protein.

Methods

In vitro cytotoxicity tests were performed according to ISO 10993–5 protocols to assess cytotoxicity index (IC₅₀) values. Acute ecotoxicity (EC₅₀) studies were performed using Daphnia similis, according to the ABNT NBR 15088 protocols. In vivo toxicity also included evaluation of acute embryotoxicity using Danio rerio (zebrafish) embryos following the OECD No. 236 guidelines. We also used Sprague Dawley rats to assess the toxicity of AgNP-GP in doses from 2.5 to 10.0 mg kg⁻¹ body weight.

Results

AgNP-GP nanoparticles were characterized through UV (405 nm), core size (20±5 nm through TEM), hydrodynamic size (70–80 nm), Zeta (ζ) potential (- 26 mV) using DLS and Powder X ray diffraction (PXRD) and EDS. PXRD showed pattern consistent with the Ag (1 1 1) peak. EC₅₀ in Daphnia similis was 4.40 (3.59–5.40) μg L⁻¹. In the zebrafish species, LC₅₀ was 177 μg L⁻¹. Oral administration of AgNP-GP in Sprague Dawley rats for a period of 28 days revealed no adverse effects in doses of up to 10.0 mg kg⁻¹ b.w. in both male and female animals.

Conclusion

The non-toxicity of AgNP-GP in rats offers a myriad of applications of AgNP-GP in health and hygiene for use as antibiotics, antimicrobial and antifungal agents.

Adaptive changes induced by noble-metal nanostructures in vitro and in vivo

The unique features of noble-metal nanostructures (NMNs) are leading to unprecedented expansion of research and exploration of their application in therapeutics, diagnostics and bioimaging fields. With the ever-growing applications of NMNs, both therapeutic and environmental NMNs are likely to be exposed to tissues and organs, requiring careful studies towards their biological effects in vitro and in vivo. Upon NMNs exposure, tissues and cells may undergo a series of adaptive changes both in morphology and function. At the cellular level, the accumulation of NMNs in various subcellular organelles including lysosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, and nucleus may interfere with their functions, causing changes in a variety of cellular functions, such as digestion, protein synthesis and secretion, energy metabolism, mitochondrial respiration, and proliferation. In animals, retention of NMNs in metabolic-, respiratory-, immune-related, and other organs can trigger significant physiological and pathological changes to these organs and influence their functions. Exploring how NMNs interact with tissues and cells and the underlying mechanisms are of vital importance for their future applications. Here, we illustrate the characteristics of NMNs-induced adaptive changes both in vitro and in vivo. Potential strategies in the design of NMNs are also discussed to take advantage of beneficial adaptive changes and avoid unfavorable changes for the proper implementation of these nanoplatforms.

Silver Nanoparticles in Zebrafish (Danio rerio) Embryos: Uptake, Growth and Molecular Responses

Silver nanoparticles (AgNPs) are widely used in commercial applications as antimicrobial agents, but there have recently been increasing concerns raised about their possible environmental and health impacts. In this study, zebrafish embryos were exposed to two sizes of AgNP, 4 and 10 nm, through a continuous exposure from 4 to 96 h post-fertilisation (hpf), to study their uptake, impact and molecular defense responses. Results showed that zebrafish embryos were significantly impacted by 72 hpf when continuously exposed to 4 nm AgNPs. At concentrations above 0.963 mg/L, significant in vivo uptake and delayed yolk sac absorption was evident; at 1.925 mg/L, significantly reduced body length was recorded compared to control embryos. Additionally, 4 nm AgNP treatment at the same concentration resulted in significantly upregulated hypoxia inducible factor 4 (HIF4) and peroxisomal membrane protein 2 (Pxmp2) mRNA expression in exposed embryos 96 hpf. In contrast, no significant differences in terms of larvae body length, yolk sac absorption or gene expression levels were observed following exposure to 10 nm AgNPs. These results demonstrated that S4 AgNPs are available for uptake, inducing developmental (measured as body length and yolk sac area) and transcriptional (specifically HIF4 and Pxmp2) perturbations in developing embryos. This study suggests the importance of particle size as one possible factor in determining the developmental toxicity of AgNPs in fish embryos.

Silver nanoparticle exposure impairs ion regulation in zebrafish embryos

The potential toxicity of silver nanoparticles (AgNPs) to the early stages of fish is still unclear. This study used zebrafish embryos as a model to investigate the toxic effects of AgNPs on ion regulation by skin ionocytes. Zebrafish embryos were exposed to AgNPs for 96 h (4-100 h post-fertilization (hpf)) or 4 h (96-100 hpf). After 96 h of exposure to 5 and 10 mg/L AgNPs, survival rates had decreased to 42% and 0%, respectively; the body length had also significantly decreased at 5 mg/L. Whole-body Na⁺ and K⁺ contents significantly decreased at 1 and 3 mg/L, while Ca²⁺ contents decreased at ≥0.1 mg/L. H⁺ secretion by the skin significantly decreased at 1 mg/L. The density of skin ionocytes labeled with rhodamine 123 (a mitochondrion marker) decreased by 25% and 55% at 1 and 3 mg/L, respectively; and 54% of ionocytes (at 3 mg/L) were deformed from an oval to a spinous shape. After 4 h of exposure to 1 and 5 mg/L, whole-body Na⁺ and Ca²⁺ contents, H⁺ secretion, and density of ionocytes had also significantly decreased. This study revealed the toxicity of AgNPs to skin ionocytes and ion regulation in the early stages of zebrafish embryos.

Developmental exposure to silver nanoparticles at environmentally relevant concentrations alters swimming behavior in zebrafish (Danio rerio)

Silver nanoparticles (Ag-NPs) are ubiquitous in household and medical products because of their antimicrobial activity. A consequence of the high volume of Ag-NP production and usage is increased amounts of Ag-NPs released into the environment. Their small size (1-100 nm) results in unique physiochemical properties that may increase toxicity relative to their bulk counterpart. Therefore, the goal of the present study was to assess the potential toxicity of environmentally relevant concentrations of Ag-NPs in zebrafish (Danio rerio). Wild-type tropical 5D zebrafish embryos were exposed to Ag-NPs from 4 to 120 h postfertilization at 0.03, 0.1, 0.3, 1, and 3 ppm (mg/L). Inductively coupled plasma-mass spectrometry confirmed concentration-dependent uptake of Ag into zebrafish as well as bioaccumulation over time. A morphological assessment revealed no significant hatching impairment, morphological abnormalities, or mortality at any concentration or time point examined. However, assessment of photomotor behavior at 3 d postfertilization (dpf) revealed significant hyperactivity in the 0.3, 1, and 3 ppm Ag-NP treatment groups. At 4 dpf, significant hyperactivity was observed only in the 3 ppm treatment group, whereas 5 dpf larvae exposed to Ag-NPs displayed no significant abnormalities in photomotor behavior. These findings suggest that nonteratogenic concentrations of Ag-NPs are capable of causing transient behavioral changes during development. Environ Toxicol Chem 2018;37:3018-3024. © 2018 SETAC.

Zebrafish as a Model to Evaluate Nanoparticle Toxicity

Nanoparticles are increasingly being developed for in vivo use, from targeted drug delivery to diagnostics, where they have enormous potential, while they are also being used for a variety of applications that can result in environmental exposure for humans. Understanding how specific nanoparticles interact with cells and cell systems is essential to gauge their safety with respect to either clinical or environmental exposure. Zebrafish is being increasingly employed as a model to evaluate nanoparticle biocompatibility. This review describes this model and how it can be used to assess nanoparticle toxicity at multiple levels, including mortality, teratogenicity, immunotoxicity, genotoxicity, as well as alterations in reproduction, behavior and a range of other physiological readouts. This review also provides an overview of studies using this model to assess the toxicity of metal, metal oxide and carbon-based nanoparticles. It is anticipated that this information will inform research aimed at developing biocompatible nanoparticles for a range of uses.

Silver nanoparticles inhibit neural induction in human induced pluripotent stem cells

Silver nanoparticles (AgNPs) have been widely used as consumer products due to their antibacterial activities. Despite their extensive use, AgNPs have been reported to cause various types of cytotoxicity, including neurotoxicity. However, the potential action of AgNPs on early fetal development has not been elucidated. This study determined the effects of AgNPs on neural induction in human induced pluripotent stem cells (iPSCs), used as a model for human fetal stage development. It was observed that exposure to AgNPs reduced the expression of several neural differentiation marker genes, including OTX2, an early biomarker for neurogenesis in iPSCs. Since neural differentiation requires ATP as a source of energy, the intracellular ATP content was also measured. It was observed that AgNPs decreased intracellular ATP levels in iPSCs. Since AgNPs suppressed energy production, a critical mitochondrial function, the effects of AgNPs on mitochondrial dynamics were further studied. The results revealed that AgNPs induced mitochondrial fragmentation and reduced the level of mitochondrial fusion protein mitofusin 1 (Mfn1). Previously, we reported that knockdown of Mfn1 in iPSCs inhibited neural induction via OTX2 downregulation. This suggested that AgNPs could induce cytotoxicity, including neurodevelopmental toxicity, via Mfn1-mediated mitochondrial dysfunction in iPSCs. Thus, mitochondrial function in iPSCs can be used for assessing the cytotoxic effects associated with nanomaterials, including AgNPs.

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.

Omics tools: New challenges in aquatic nanotoxicology?

In recent years, the implication of genomics into ecotoxicological studies has been studied closely to allow a better understanding of organism's responses to environmental contaminants including engineering nanomaterials (ENMs). ENMs are increasingly produced for various applications including cosmetics, electronics, sports equipment, biomedicine and agriculture. Because of their small size, ENMs possess chemical or physical characteristics improved compared to the corresponding macro-sized material. As their application expend, the release of manufactured ENMs into the environment is likely to increase and concern over impacts for the aquatic ecosystem is growing. Several studies reported deleterious effect of ENMs to aquatic organisms, but there is little information about the molecular mechanisms of toxicity. The development of ecotoxicogenomic approaches will improve the characterization of cellular and molecular modes of action of ENMs to aquatic organisms and allow a better prediction of contaminants toxicity. This paper presents an overview of transciptomic/proteomic studies in freshwater and marine organisms exposed to ENMs. Overall, induction of gene expression in relations to defense mechanisms, immune responses, growth and reproduction were measured after ENMs exposures of organisms, but with different patterns depending on exposure duration and concentrations used. In addition, some studies reported a positive correlation between gene expression and cellular modifications, but not at the individual level.

Ecophysiological perspectives on engineered nanomaterial toxicity in fish and crustaceans

Engineered nanomaterials (ENMs) are incorporated into numerous industrial, clinical, food, and consumer products and a significant body of evidence is now available on their toxicity to aquatic organisms. Environmental ENM concentrations are difficult to quantify, but production and release estimates suggest wastewater treatment plant effluent levels ranging from 10^-4 to >10¹μgL^-1 for the most common formulations by production volume. Bioavailability and ENM toxicity are heavily influenced by water quality parameters and the physicochemical properties and resulting colloidal behaviour of the particular ENM formulation. ENMs generally induce only mild acute toxicity to most adult fish and crustaceans under environmentally relevant exposure scenarios; however, sensitivity may be considerably higher for certain species and life stages. In adult animals, aquatic ENM exposure often irritates respiratory and digestive epithelia and causes oxidative stress, which can be associated with cardiovascular dysfunction and the activation of immune responses. Direct interactions between ENMs (or their dissolution products) and proteins can also lead to ionoregulatory stress and/or developmental toxicity. Chronic and developmental toxicity have been noted for several common ENMs (e.g. TiO₂, Ag), however more data is necessary to accurately characterize long term ecological risks. The bioavailability of ENMs should be limited in saline waters but toxicity has been observed in marine animals, highlighting a need for more study on possible impacts in estuarine and coastal systems. Nano-enabled advancements in industrial processes like water treatment and remediation could provide significant net benefits to the environment and will likely temper the relatively modest impacts of incidental ENM release and exposure.

Natural water as the test medium for Ag and CuO nanoparticle hazard evaluation: An interlaboratory case study

Engineered nanoparticles (NPs) have realistic potential of reaching natural waterbodies and of exerting toxicity to freshwater organisms. The toxicity may be influenced by the composition of natural waters as crucial NP properties are influenced by water constituents. To tackle this issue, a case study was set up in the framework of EU FP7 NanoValid project, performing an interlaboratory hazard evaluation of NPs in natural freshwater. Ag and CuO NPs were selected as model NPs because of their potentially high toxicity in the freshwater. Daphnia magna (OECD202) and Danio rerio embryo (OECD236) assays were used to evaluate NP toxicity in natural water, sampled from Lake Greifen and Lake Lucerne (Switzerland). Dissolution of the NPs was evaluated by ultrafiltration, ultracentrifugation and metal specific sensor bacteria. Ag NP size was stable in natural water while CuO NPs agglomerated and settled rapidly. Ag NP suspensions contained a large fraction of Ag(+) ions and CuO NP suspensions had low concentration of Cu(2+) ions. Ag NPs were very toxic (48 h EC50 1-5.5 μg Ag/L) to D. magna as well as to D. rerio embryos (96 h EC50 8.8-61 μg Ag/L) in both standard media and natural waters with results in good agreement between laboratories. CuO NP toxicity to D. magna differed significantly between the laboratories with 48 h EC50 0.9-11 mg Cu/L in standard media, 5.7-75 mg Cu/L in Lake Greifen and 5.5-26 mg Cu/L in Lake Lucerne. No toxicity of CuO NP to zebrafish embryos was detected up to 100 mg/L independent of the medium used. The results show that Ag and CuO NP toxicity may be higher in natural water than in the standard media due to differences in composition. NP environmental hazard evaluation can and should be carried out in natural water to obtain more realistic estimates on the toxicity.

Environmental concentration of carbamazepine accelerates fish embryonic development and disturbs larvae behavior

Environmental pollution caused by pharmaceuticals has been recognized as a major threat to the aquatic ecosystems. Carbamazepine, as the widely prescribed antiepileptic drug, has been frequently detected in the aquatic environment and has created concerns about its potential impacts in the aquatic organisms. The effects of carbamazepine on zebrafish embryos were studied by examining their phenotype, behavior and molecular responses. The results showed that carbamazepine disturbed the normal growth and development of exposed zebrafish embryos and larvae. Upon exposure to carbamazepine at 1 μg/L, the hatching rate, body length, swim bladder appearance and yolk sac absorption rate were significantly increased. Embryos in treatment groups were more sensitive to touch and light stimulation. At molecular level, exposure to an environmentally relevant concentration (1 μg/L) of carbamazepine disturbed the expression pattern of neural-related genes of zebrafish embryos and larvae. This study suggests that the exposure of fish embryo to antiepileptic drugs, at environmentally relevant concentrations, affects their early development and impairs their behavior. Such impacts may have future repercussions by affecting fish population structure.

Zebrafish: A complete animal model to enumerate the nanoparticle toxicity

Presently, nanotechnology is a multi-trillion dollar business sector that covers a wide range of industries, such as medicine, electronics and chemistry. In the current era, the commercial transition of nanotechnology from research level to industrial level is stimulating the world’s total economic growth. However, commercialization of nanoparticles might offer possible risks once they are liberated in the environment. In recent years, the use of zebrafish (Danio rerio) as an established animal model system for nanoparticle toxicity assay is growing exponentially. In the current in-depth review, we discuss the recent research approaches employing adult zebrafish and their embryos for nanoparticle toxicity assessment. Different types of parameters are being discussed here which are used to evaluate nanoparticle toxicity such as hatching achievement rate, developmental malformation of organs, damage in gill and skin, abnormal behavior (movement impairment), immunotoxicity, genotoxicity or gene expression, neurotoxicity, endocrine system disruption, reproduction toxicity and finally mortality. Furthermore, we have also highlighted the toxic effect of different nanoparticles such as silver nanoparticle, gold nanoparticle, and metal oxide nanoparticles (TiO₂, Al2O₃, CuO, NiO and ZnO). At the end, future directions of zebrafish model and relevant assays to study nanoparticle toxicity have also been argued.

Ecotoxicity Effects of Nanomaterials on Aquatic Organisms

The increasing production and use of engineered nanomaterials raise concerns about inadvertent exposure and the potential for adverse effects on the aquatic environment. The aim of this chapter is focused on studies of nanotoxicity in different models of aquatic organisms and their impact. Moreover, the chapter provides an overview of nanoparticles, their applications, and the potential nanoparticle-induced toxicity in aquatic organisms. The topics discussed in this chapter are the physicochemical characteristic of nanomaterials (size, aggregation, morphology, surface charge, reactivity, dissolution, etc.) and their influence on toxicity. Further, the text discusses the direct effect of nanomaterials on development stage (embryonic and adult) in aquatic organisms, the mechanism of action as well as the toxicity data of nanomaterials in different species.f action as well as the toxicity data of nanomaterials in different species.