Differential alteration in reproductive toxicity of medaka fish on exposure to nanoscale zerovalent iron and its oxidation products

Remediation of Cr(VI) Polluted Groundwater Using Zero-Valent Iron Composites: Preparation, Modification, Mechanisms, and Environmental Implications

The extensive application of chromium (Cr) in many industries has inevitably resulted in the release of Cr(VI) into the groundwater environment, thus posing damage to the ecosystem and human health. Nano zero-valent iron (nZVI) has been widely studied and applied in the remediation of Cr(VI)-contaminated water as an ideal material with high reductive capacity, which enables the transformation of teratogenic and carcinogenic Cr(VI) into less toxic Cr(III). This review comprehensively summarizes the preparation and modification methods of nZVI Cr(VI) removal performance and mechanisms by nZVI and modified nZVI materials. The field applications of nZVI-based materials, such as combining the injection well and the permeable reactive barrier (PRB) to remove Cr(VI) in groundwater, have been reported. Subsequently, the potential toxicity of nZVI-based materials to organisms during environmental application has been highlighted in the current study. Finally, the review outlines potential improvements and explores future directions for the use of nZVI-based materials in groundwater contamination remediation.

Fe-NPs and Zn-NPs: Advancing Aquaculture Performance Through Nanotechnology

Aquaculture is a growing industry facing several challenges, including disease control, water quality management, and sustainable feed production. One potential solution to these challenges is the use of trace elements such as iron (Fe) and zinc (Zn), either in their conventional form or as nanoparticles (NPs). Aquatic animals need these micronutrients for normal growth, physiological processes, and overall health. In marine species, iron boosts development, immunity, and disease resistance. At the same time, zinc enhances metabolism, synthesizes essential enzymes, and produces hormones that play a part in defenses, growth, reproduction, and antioxidative activities. According to this review, species-specific requirements by different Fe and Zn compounds have all emphasized the impacts on animal growth and development, antioxidant capacity, reproductive efficiency, and immunological response. However, NPs of Fe and Zn have been found to have higher bioavailability and efficacy than conventional forms. This work examines the effects of applications of Fe and Fe nanoparticles (Fe-NPs) and Zn and Zn nanoparticles (Zn-NPs) in aquaculture. However, the source of Fe and Zn in aquaculture species and administration volume may significantly impact efficacy. Nanotechnology boosts the positive benefits of Fe and Zn by converting them to their nanoforms (Fe-NPs) and (Zn-NPs), which are better used by animals and have a broader intake range. As a result, Fe-NPs and Zn-NPs offer an effective method for using nutrients in aquaculture.

A Pretty Kettle of Fish: A Review on the Current Challenges in Mediterranean Teleost Reproduction

The Mediterranean region is facing several environmental changes and pollution issues. Teleosts are particularly sensitive to these challenges due to their intricate reproductive biology and reliance on specific environmental cues for successful reproduction. Wild populations struggle with the triad of climate change, environmental contamination, and overfishing, which can deeply affect reproductive success and population dynamics. In farmed species, abiotic factors affecting reproduction are easier to control, whereas finding alternatives to conventional diets for farmed teleosts is crucial for enhancing broodstock health, reproductive success, and the sustainability of the aquaculture sector. Addressing these challenges involves ongoing research into formulating specialized diets, optimizing feeding strategies, and developing alternative and sustainable feed ingredients. To achieve a deeper comprehension of these challenges, studies employing model species have emerged as pivotal tools. These models offer advantages in understanding reproductive mechanisms due to their well-defined physiology, genetic tractability, and ease of manipulation. Yet, while providing invaluable insights, their applicability to diverse species remains constrained by inherent variations across taxa and oversimplification of complex environmental interactions, thus limiting the extrapolation of the scientific findings. Bridging these gaps necessitates multidisciplinary approaches, emphasizing conservation efforts for wild species and tailored nutritional strategies for aquaculture, thereby fostering sustainable teleost reproduction in the Mediterranean.

Single and mixture toxicity of cadmium and copper to swim bladder in early life stages of Japanese medaka (Oryzias latipes)

Toxicity observed in aquatic ecosystems often cannot be explained by the action of a single pollutant. Likewise, evaluation standards formulated by a single effect cannot truly reflect the environmental quality requirements. The study of mixtures is needed to provide environmental relevance and knowledge of combined toxicity. In this study, the embryos of Japanese medaka (Oryzias latipes) were treated with individual and binary mixture of copper (Cu) and cadmium (Cd) until 12 days post-fertilization (dpf). Hatching, mortality, development, histology and gene expression were assessed. Our results showed that the highest concentration mixture of Cd (10 mg/L) and Cu (1 mg/L) affected survival, hatching time and hatching success. Occurrence of uninflated swim bladder was the highest (value) with exposure to 10 mg/L Cd. Swim bladder was commonly over-inflated in a mixture (0.1 mg/L Cd + 1.0 mg/L Cu) exposure. Individuals exposed to the mixture (0.1 Cd + 1.0 Cu mg/L) showed up to a 7.69% increase in swim bladder area compared to the control group. The mixtures containing 0.1 or 10 mg/L Cd, each with 1.0 mg/L Cu resulted in significantly increased of Pbx1b expression, higher than any Cd or Cu alone (p < 0.01). In the co-exposure group (0.1/10 Cd + 1.0 Cu mg/L), Pbx1b expression was found at 12 dpf but not 7 dpf in controls. Higher concentrations of Cd may progressively reduce Pbx1b expression, potentially explaining why 75% of individuals in the 10 mg/L Cd group failed to inflate their swim bladders. Additionally, the swim bladder proved to be a valuable bio-indicator for biological evaluation.

Ovaries of guppies (Poecilia reticulata) investigated in pre-embryonic, embryonic and post-embryonic stages after exposure to maghemite nanoparticles (y-Fe2O3) associated with Roundup® and glyphosate, followed by recovery period evaluation

Iron oxide nanoparticles (IONP) are promising alternatives to environmental remediation, so this study investigates IONP single and associated to contaminants, in this case, glyphosate (GLY) and Roundup® (GBH) in Poecilia reticulata (guppy). The guppies have internal development, therefore this study analyzed female gonads to establish the developmental stages of P. reticulata and evaluate effects of exposure (7, 14 and 21 days) and post-exposure (same period) to the treatments with Iron ions 0.3mg Fe/L (IFe); IONP 0.3mg Fe/L; IONP 0.3 mgFe/L + GBH 0,65mgGLY/L (IONP+GBH1); IONP 0.3 mgFe/L + GBH 1.30 mgGLY/L (IONP+GBH2); and IONP 0.3 mgFe/L + GLY 0.65 mg/L (IONP+GLY). The development was organized in immature, development, and gestation phases. The damage in all treatments after 21 days of exposure was evident in reaction patterns regressive inflammatory, and circulatory including total histopathologic index of liver, nevertheless there was a damage recovery trend during post-exposure period.

Impacts of engineered iron nanoparticles on oxidative stress, fatty acid composition, and histo-architecture of the smooth scallop Flexopecten glaber

Engineered iron nanoparticles are widely used in environmental remediation, yet their potential toxic effects on marine biota remain poorly elucidated. This study aimed to gain insight into the nanoscale zero-valent iron (NZVI) toxicity mechanisms for marine invertebrates. Aside from the effect on oxidative status and histopathology, the effect of NZVI on lipid metabolism in bivalves was studied for the first time. To this end, specimens of Flexopecten glaber were exposed to ascending concentrations (0.5, 1, and 1.5 mg/L) of NZVI for 96 h. Results illustrate differential patterns of iron accumulation in the gills and the digestive gland. By increasing NZVI concentrations, the total iron level tended to markedly increase in the gills and decrease in the digestive gland, reaching 132 and 37.6 μg/g DW, respectively, in the specimens exposed to 1.5 mg/L. Biochemical and cellular biomarkers highlighted that NZVI caused oxidative stress (measured as hydrogen peroxide, malondialdehyde, and advanced oxidation protein product levels) and alterations of antioxidant defense systems, including reduced glutathione, non-protein thiol, glutathione peroxidase, superoxide dismutase, and catalase. Modulation of lipid metabolism with changed fatty acid compositions (mainly an increase in the saturation and a decrease in unsaturation levels) was also observed in both gills and digestive gland. Moreover, several histological damages, including lipofuscin accumulation, infiltrative inflammations, and digestive tubule alterations, were observed in the two studied organs, providing supplementary evidence regarding the toxic effect of NZVI. This study adds to the growing body of evidence pointing to the hazardous impacts of iron NPs on aquatic ecosystems.

Can the toxicity of polyethylene microplastics and engineered nanoclays on flatfish (Solea senegalensis) be influenced by the presence of each other?

Microplastics and nanomaterials are applied in a myriad of commercial and industrial applications. When leaked to natural environments, such small particles might threaten living organisms' health, particularly when considering their potential combination that remains poorly investigated. This study investigated the physiological and biochemical effects of polyethylene (PE; 64-125 μm in size, 0.1, 1.0, and 10.0 mg·L^-1) single and combined with an engineered nanomaterial applied in antifouling coatings, the copper-aluminium layered double hydroxides (Cu-Al LDH; 0.33, 1.0, and 3.33 mg·L^-1) in the flatfish Solea senegalensis larvae (8 dph) after 3 h exposure, in a full factorial design. Particles ingestion, histopathology, and biochemical biomarkers were assessed. Fish larvae presented <1 PE particles in their gut, independently of their concentration in the medium. The histological health index showed minimal pathological alterations at PE combined exposure, with a higher value observed at 1 mg LDH·L^-1 × 0.1 mg PE·L^-1. Gut deformity and increased antioxidant defences (catalase), neurotransmission (acetylcholinesterase), and aerobic energy production (electron transport system) were observed at PE ≥ 1.0 mg·L^-1. No oxidative damage (lipid peroxidation) or alterations in the detoxification capacity (glutathione-S-transferase) was observed on single and combined exposures. PE, combined or not with Cu-Al LDH, does not seem to compromise larvae's homeostasis considering levels reported so far in the marine and aquaculture environments. However, harsh effects are expected with MP contamination rise, as projections suggest.

Recovery trend to co-exposure of iron oxide nanoparticles (γ-Fe2O3) and glyphosate in liver tissue of the fish Poecilia reticulata

Citrate-coated iron oxide nanoparticles (IONPs) have potential use in environmental remediation, with possibilities in decontaminating aquatic environments exposed to toxic substances. This study analyzed IONPs associated to Roundup Original, a glyphosate-based herbicide (GBH), and pure glyphosate (GLY), through ultrastructural and histopathological biomarkers in liver tissue, from females of Poecilia reticulata exposed to: iron ions (0.3 mg/L) (IFe) and IONPs (0.3 mgFe/L) associated with GLY (0.65 mg/L) and GBH (0.65 mgGLY/L (IONP + GBH1) and 1.30 mgGLY/L (IONP + GBH2)) for a period of 7, 14 and 21 days, followed by an equal post-exposure period only in reconstituted water. For the assays, the synthetized IONPs had crystalline and rounded shape with an average diameter of 2,90 nm, hydrodynamic diameter 66,6 mV, zeta potential -55,4 and diffraction profile of maghemite (γ-Fe2O3). The data obtained by biomarkers indicated a high inflammatory response in all treatments. These same parameters, considered during the post-exposure period indicated recovery in reaction patterns of circulatory disturbances and regressive changes, resulting in average reductions of 37,53 points in IFe, 21 points in IONP + GBH1, 15 points in IONP + GBH2 and 11 points in IONP + GLY in total histopathological index of liver after 21 days post-exposure. However, although the cellular and tissue responses were significant, there was no change in the condition factor and hepatosomatic index, denoting resilience of the experimental model.

In situ nanoremediation of soils and groundwaters from the nanoparticle's standpoint: A review

Anthropogenic pollution coming from industrial processes, agricultural practices and consumer products, results in the release of toxic substances into rural and urban environments. Once released, these chemicals migrate through the atmosphere and water, and find their way into matrices such as sediments and groundwaters, thus making large areas potentially uninhabitable. Common pollutants, including heavy metal(loid)s, radionuclides, aliphatic hydrocarbons and halogenated organics, are known to adversely affect physiological systems in animal species. Pollution can be cleaned up using techniques such as coagulation, reverse osmosis, oxidation and biological methods, among others. The use of nanoparticles (NPs) extends the range of available technologies and offers particular benefits, not only by degrading, transforming and immobilizing contaminants, but also by reaching inaccessible areas and promoting biotic degradation. The development of NPs is understandably heralded as an environmentally beneficial technology; however, it is only now that the ecological risks associated with their use are being evaluated. This review presents recent developments in the use of engineered NPs for the in situ remediation of two paramount environmental matrices: soils and groundwaters. Emphasis will be placed on (i) the successful applications of nano-objects for environmental cleanup, (ii) the potential safety implications caused by the challenging requirements of [high reactivity toward pollutants] vs. [none reactivity toward biota], with a thorough view on their transport and evolution in the matrix, and (iii) the perspectives on scientific and regulatory challenges. To this end, the most promising nanomaterials will be considered, including nanoscale zerovalent iron, nano-oxides and carbonaceous materials. The purpose of the present review is to give an overview of the development of nanoremediators since they appeared in the 2000s, from their chemical modifications, mechanism of action and environmental behavior to an understanding of the problematics (technical limitations, economic constraints and institutional precautionary approaches) that will drive their future full-scale applications.

Ovarian toxicity of nanoparticles

The ovary is a highly important organ for female reproduction. The main functions include sex steroid hormone synthesis, follicular development, and achievement of oocyte meiotic and development competence for proper fertilization. Nanoparticle (NP) exposure is becoming unavoidable because of its wide use in different products, including cosmetics, food, health, and personal care products. Studies examining different nonreproductive tissues or systems have shown that characteristics such as the size, shape, core material, agglomeration, and dissolution influence the effects of NPs. However, most studies evaluating NP-mediated reproductive toxicity have paid little or no attention to the influence of the physicochemical characteristics of NP on the observed effects. As accumulating evidence indicates that NP may reach the ovary to impair proper functions, this review summarizes the available data on NP accumulation in ovarian tissue, as well as data describing toxicity to ovarian functions, including sex steroid hormone production, follicular development, oocyte quality, and fertility. Due to their toxicological relevance, this review also describes the main physicochemical characteristics involved in NP toxicity and the importance of considering NP physicochemical characteristics as factors influencing the ovarian toxicity of NPs. Finally, this review summarizes the main mechanisms of toxicity described in ovarian cells.

Toxicity evaluation of bulk and nanosheet MoS2 catalysts using battery bioassays

Herein, the main aim is to study the influence of the materials' structural properties on their ecotoxicological properties. The acute toxicity of the bulk (molybdenum disulfide) MoS₂ and 2D nanosheet MoS₂ was investigated using organisms of four different taxonomic groups. Ultrasound-assisted liquid-phase exfoliation method was used for preparing 2D nanosheets from bulk MoS₂. Bulk and nanosheet MoS₂ were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analyses. The acute toxicity of the bulk and nanosheet MoS₂ catalysts was evaluated with four different bioassays using the test organisms Vibrio fischeri (a marine photobacterium), Pseudokirchnerialla subcapitata (a freshwater microalga), Daphnia magna (a freshwater crustacean) and the freshwater duckweed Spirodela polyrhiza. The toxic effect of the materials depended on their structural/size features and the type/sensitivity of the test organism. Generally speaking, bulk MoS₂ was more toxic than its nanosheet form. The freshwater crustacean Daphnia magna appeared to be the most suitable, easy-to-handle, and at the same time sensitive test organism for bulk and nanosheet MoS₂ among the tested organisms.

The Crucial Role of Environmental Coronas in Determining the Biological Effects of Engineered Nanomaterials

In aquatic environments, a large number of ecological macromolecules (e.g., natural organic matter (NOM), extracellular polymeric substances (EPS), and proteins) can adsorb onto the surface of engineered nanomaterials (ENMs) to form a unique environmental corona. The presence of environmental corona as an eco-nano interface can significantly alter the bioavailability, biocompatibility, and toxicity of pristine ENMs to aquatic organisms. However, as an emerging field, research on the impact of the environmental corona on the fate and behavior of ENMs in aquatic environments is still in its infancy. To promote a deeper understanding of its importance in driving or moderating ENM toxicity, this study systemically recapitulates the literature of representative types of macromolecules that are adsorbed onto ENMs; these constitute the environmental corona, including NOM, EPS, proteins, and surfactants. Next, the ecotoxicological effects of environmental corona-coated ENMs on representative aquatic organisms at different trophic levels are discussed in comparison to pristine ENMs, based on the reported studies. According to this analysis, molecular mechanisms triggered by pristine and environmental corona-coated ENMs are compared, including membrane adhesion, membrane damage, cellular internalization, oxidative stress, immunotoxicity, genotoxicity, and reproductive toxicity. Finally, current knowledge gaps and challenges in this field are discussed from the ecotoxicology perspective.