Insights into the CuO nanoparticle ecotoxicity with suitable marine model species

Heat stress mediates toxicity of rutile titanium dioxide nanoparticles on fertilisation capacity in the broadcast spawning mussel Mytilus galloprovincialis

Titanium dioxide nanoparticle (nTiO2) pollution of marine environments is rapidly increasing with potentially deleterious effects on wildlife. Yet, the impacts of nTiO2 on reproduction remain poorly understood. This is especially the case for broadcast spawners, who are likely to be more severely impacted by environmental disturbances because their gametes are directly exposed to the environment during fertilisation. In addition, it is unclear whether rising water temperatures will further exacerbate the impact of nTiO2 toxicity. Here, in a series of fertilisation trials, we systematically examine the main and interactive effects of nTiO2 exposure and seawater temperature on fertilisation success in the Mediterranean mussel Mytilus galloprovincialis. Specifically, our fertilisation trials explored whether nTiO2 exposure influences fertilisation rates when (i) eggs alone are exposed, (ii) both sperm and eggs are exposed simultaneously, and (iii) whether increases in seawater temperature interact with nTiO2 exposure to influence fertilisation rates. We also ask whether changes in nTiO2 concentrations influence key sperm motility traits using computer-assisted sperm analysis (CASA). In fertilisation trials for treatment groups (i) and (ii), we found no main effects of nTiO2 at environmentally relevant concentrations of 5, 10 and 50 μg L-1 on fertilisation capacity relative to the control. Consistent with these findings, we found no effect of nTiO2 exposure on sperm motility. However, in treatment group (iii), when fertilisation trials were conducted at higher temperatures (+6 °C), exposure of gametes from both sexes to 10 μg L-1 nTiO2 led to a reduction in fertilisation rates that was significantly greater than when gametes were exposed to elevated temperature alone. These interacting effects of nTiO2 exposure and seawater temperature demonstrate the toxic potential of nTiO2 for fertilisation processes in a system that is likely to be impacted heavily by predicted future increases in sea surface temperatures.

Response surface methology for enzymatic ultrasound assisted sp-ICP-MS assessment of cuonps in seafood: Occurrence and bioaccumulation

A novel approach for a reliable extraction and analytical characterization of copper oxide nanoparticles (CuONPs) at trace levels on seafood samples was tuned up using single particle inductively coupled plasma mass spectrometry (sp-ICP-MS). Variables for enzymatic extraction of CuONPs were optimised via response surface methodology (RSM) analysis, to maximize both the extracted CuONPs mass and number concentrations without altering their native size and morphology. Analytical performance features of the whole (enzymatic ultrasound-assisted/sp-ICP-MS) approach were thoroughly evaluated. Furthermore, the proposed extraction approach demonstrated higher efficiency compared to an alternative alkaline hydrolysis-based methodology. Finally, nine seafood samples from diverse nature were analysed for CuONPs content and particle size by sp-ICP-MS, revealing significant NPs concentrations in most cases. Attained results enabled the assessment of health risks associated with CuONPs bioaccumulation in seafood organisms.

Anthracene detoxification by Laccases from indigenous fungal strains Trichoderma lixii FLU1 and Talaromyces pinophilus FLU12

The persistence and ubiquity of polycyclic aromatic hydrocarbons (PAHs) in the environment necessitate effective remediation strategies. Hence, this study investigated the potential of purified Laccases, TlFLU1L and TpFLU12L, from two indigenous fungi Trichoderma lixii FLU1 (TlFLU1) and Talaromyces pinophilus FLU12 (TpFLU12), respectively for the oxidation and detoxification of anthracene. Anthracene was degraded with vmax values of 3.51 ± 0.06 mg/L/h and 3.44 ± 0.06 mg/L/h, and Km values of 173.2 ± 0.06 mg/L and 73.3 ± 0.07 mg/L by TlFLU1L and TpFLU12L, respectively. The addition of a mediator compound 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) to the reaction system significantly increased the degradation of anthracene, with up to a 2.9-fold increase in vmax value and up to threefold decrease in Km values of TlFLU1L and TpFLU12L. The GC-MS analysis of the metabolites suggests that anthracene degradation follows one new pathway unique to the ABTS system-hydroxylation and carboxylation of C-1 and C-2 position of anthracene to form 3-hydroxy-2-naphthoic acid, before undergoing dioxygenation and side chain removal to form chromone which was later converted into benzoic acid and CO2. This pathway contrasts with the common dioxygenation route observed in the free Laccase system, which is observed in the second degradation pathways. Furthermore, toxicity tests using V. parahaemolyticus and HT-22 cells, respectively, demonstrated the non-toxic nature of Laccase-ABTS-mediated metabolites. Intriguingly, analysis of the expression level of Alzheimer's related genes in HT-22 cells exposed to degradation products revealed no induction of neurotoxicity unlike untreated cells. These findings propose a paradigm shift for bioremediation by highlighting the Laccase-ABTS system as a promising green technology due to its efficiency with the discovery of a potentially less harmful degradation pathway, and the production of non-toxic metabolites.

An overview on dispersion procedures and testing methods for the ecotoxicity testing of nanomaterials in the marine environment

Considerable efforts have been devoted to develop or adapt existing guidelines and protocols, to obtain robust and reproducible results from (eco)toxicological assays on engineered nanomaterials (NMs). However, while many studies investigated adverse effects of NMs on freshwater species, less attention was posed to the marine environment, a major sink for these contaminants. This review discusses the procedures used to assess the ecotoxicity of NMs in the marine environment, focusing on the use of protocols and methods for preparing NMs dispersions and on the NMs physicochemical characterization in exposure media. To this purpose, a critical analysis of the literature since 2010 was carried out, based on the publication of the first NMs dispersion protocols. Among the 89 selected studies, only <5 % followed a standardized dispersion protocol combined with NMs characterization in ecotoxicological media, while more than half used a non-standardized dispersion method but performed NMs characterization. In the remaining studies, only partial or no information on dispersion procedures or on physicochemical characterization was provided. This literature review also highlighted that metal oxides NMs were the most studied (42 %), but with an increasing interest in last years towards nanoplastics (14 %) and multicomponent nanomaterials (MCNMs, 7 %), in line with the growing attention on these emerging contaminants. For all these NMs, primary producers as algae and bacteria were the most studied groups of marine species, in addition to mollusca, while organisms at higher trophic levels were less represented, likely due to challenges in evaluating adverse effects on more complex organisms. Thus, despite the wide use of NMs in different applications, standard dispersion protocols are not often used for ecotoxicity testing with marine species. However, the efforts to characterize NMs in ecotoxicological media recognize the importance of following conditions that are as standardized as possible to support the ecological hazard assessment of NMs.

The effects of green synthesized anionic cupric oxide nanoparticles on Zaraibi goat spermatozoa during cryopreservation with and without removal of seminal plasma

Sperm motility, normal morphology, viability, spermatozoa DNA damage, and lipid peroxidation are all affected by semen cryopreservation. The goal of this study was to see how effective cupric oxide nanoparticles (CuONPs) are as a cryo-extender additive on post-thawed sperm parameters. An artificial vagina was used to collect semen samples from five mature Zaraibi bucks (2-3 years). Ejaculates were pooled and separated into two fractions (A&B), a fraction (A) was left without being centrifuged and a fraction (B) was centrifuged to remove seminal plasma. Both fractions were diluted with tris egg yolk citrate extender (TECE) and then divided into five equal aliquots, each supplemented with (0, 10, 20, 40, and 60 ppm/ml) CuONPs. The findings revealed that removing seminal plasma before cryopreservation harms sperm parameters. Sperm motility, viability index, membrane integrity, biochemical antioxidant marker, DNA integrity, and MDA level improved after supplementation with CuONPs up to 60 ppm/ml, the most prominent significant positive effect was obtained with the highest dose (60 ppm/ml) without removal of the seminal plasm compared to control group. In conclusion: The presence of seminal plasma with a high concentration of CuONPs (up to 60 ppm/ml) may help to mitigate the negative effects of cryo-preservation.

Experimental and Computational Studies on the Interaction of a Dansyl-Based Fluorescent Schiff Base Ligand with Cu2+ Ions and CuO NPs

We studied the interaction of Cu²⁺ ions and CuO nanoparticles with the fluorescent Schiff base ligand H₃L, which derives from the condensation of 4-formyl-3-hydroxybenzoic acid with N-(2-aminobenzyl)-5-(dimethylamino)naphthalene-1-sulfonamide (DsA). A detailed assignment of the most significant bands of the electronic and infrared spectra of H₃L and DsA was performed using DFT methods, based on both crystal structures. The affinity of H₃L to react with Cu²⁺ ions in solution (K_B = 9.01 10³ L mol⁻¹) is similar to that found for the Cu²⁺ ions present on the surface of CuO NPs (K_B = 9.84 10³ L mol⁻¹). Fluorescence spectroscopic measurements suggest five binding sites for H₃L on the surface of the CuO NPs used. The µ-XRF analysis indicates that a polycrystalline sample of CuO-H₃L NPs contains 15:1 Cu:S molar ratio (CuO:H₃L). ATR-FTIR spectroscopy, supported by DFT calculations, showed that the HL²⁻ (as a phenolate and sulfonamide anion) is coordinated to superficial Cu²⁺ ions of the CuO NPs through their azomethine, sulphonamide, and phenolic groups. A solution of H₃L (126 ppb) shows sensitive responses to CuO NPs, with a limit of detection (LOD) of 330 ppb. The working range for detection of CuO NPs with [H₃L] = 126 ppb was 1.1–9.5 ppm. Common metal ions in water, such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Fe³⁺, and Al³⁺ species, do not interfere significantly with the detection of CuO NPs.

Bioaccumulation and biomagnification effects of nano-TiO2 in the aquatic food chain

The increasing production of nano-TiO₂ has attracted extensive concerns about the ecological consequence and health risk of these compounds in natural ecosystem. However, little is known about its toxicity on zooplankton, especially its possibility to access to the food chain via dietary exposure. To address this concern, the toxic and cumulative effects of nano-TiO₂ on an aquatic food chain were explored through two trophic levels independently or jointly including producer and consumer. The results revealed that exposure to suspensions of nanomaterials had negative effects on both producers and consumers. Specifically, nanoparticles reduced the density of algal cells in a concentration-dependent way, and hatching life expectancy, average lifespan, net reproductive rate, and population intrinsic growth rate of rotifers decreased significantly with the concentration of nanomaterials increased (P < 0.05). Notably, nanoparticles accumulated in algal cells and were transferred to consumers through dietary exposure. Biomagnification of nano-TiO₂ was observed in this simplified food chain, as many of the biomagnification factor (BMF) values in this study were >1. Exposure concentration, exposure time and their interactions play a strong part in the accumulation of nanoparticles in algae and rotifers. Overall, the present findings confirmed that nano-TiO₂ was deleterious to plankton, posing a significant environmental threat to aquatic ecosystems. Graphical abstract.

Exposure of adult sand dollars (Scaphechinus mirabilis) (Agassiz, 1864) to copper oxide nanoparticles induces gamete DNA damage

The increase in the number of products containing nanoparticles (NPs) poses a real threat to the environment. Recently, more evidence has been added to predictive models about the presence of NPs in various natural and anthropogenic systems. The acute toxicity of most aquatic NPs has now been well documented. However, data such as the ecotoxicological significance of the long-lasting effects of NPs on the reproductive system and gamete quality of aquatic organisms are still relatively scarce. Therefore, a 10-day experiment was carried out on the sand dollar Scaphechinus mirabilis (Agassiz, 1864) exposed to low (20 and 40 μg/L) concentrations of copper oxide nanoparticles (CuO NPs). An accumulation of copper in tissues and a significant increase in lipid peroxidation product concentrations after exposure to NP were observed. A significant decrease in the fertilization rate was shown at 40 μg/L. No significant changes in embryonic or larval development were found. However, comet analysis results showed a significant increase in DNA damage in spermatozoa exposed to CuO NPs, which may further manifest as negative effects at later developmental stages or in subsequent generations.

The impacts of metal-based engineered nanomaterial mixtures on microbial systems: A review

The last decade has witnessed tremendous growth in the commercial use of metal-based engineered nanomaterials (ENMs) for a wide range of products and processes. Consequently, direct and indirect release into environmental systems may no longer be considered negligible or insignificant. Yet, there is an active debate as to whether there are real risks to human or ecological health with environmental exposure to ENMs. Previous research has focused primarily on the acute effects of individual ENMs using pure cultures under controlled laboratory environments, which may not accurately reveal the ecological impacts of ENMs under real environmental conditions. The goal of this review is to assess our current understanding of ENM effects as we move from exposure of single to multiple ENMs or microbial species. For instance, are ENMs' impacts on microbial communities predicted by their intrinsic physical or chemical characteristics or their effects on single microbial populations; how do chronic ENM interactions compare to acute toxicity; does behavior under simplified laboratory conditions reflect that in environmental media; finally, is biological stress modified by interactions in ENM mixtures relative to that of individual ENM? This review summarizes key findings and our evolving understanding of the ecological effects of ENMs under complex environmental conditions on microbial systems, identifies the gaps in our current knowledge, and indicates the direction of future research.

Current trends and challenges in analysis and characterization of engineered nanoparticles in seawater

With the increasingly wide use of engineered nanoparticles (ENPs), their release into the environment makes it important to determine in what quantitates they occur in aquatic systems and to understand their fate therein. In particular, detection and quantification of ENPs in seawater is challenging and often requires analytical methods to perform close to the feasibility confines. This review is aimed at critical analysis of current and emerging capabilities of analytical methods as have been employed for the analysis and characterization of ENPs in seawater in the last decade. An emphasis is given to the most reliable experimental strategies focused on avoiding the high-salt matrix effect and isolation and enrichment of the nanoparticulate fraction prior to analysis. Advanced analytical methodology in use basically relies on the application of elemental mass spectrometry to determine various particle-core metals and its single-particle mode to characterize the seawater-mediated transformation of ENPs, including dissolution, aggregation, etc. On the other hand, common microscopy, light scattering or X-ray based techniques are not sensitive enough to acquire the transformation information from real seawater samples. Finally, attention is pinpointed upon an acute shortcoming of the current research which is in the overwhelming majority of cases restricted to samples spiked with ENPs and often at excessive concentration levels.

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.

"Nanosize effect" in the metal-handling strategy of the bivalve Scrobicularia plana exposed to CuO nanoparticles and copper ions in whole-sediment toxicity tests

To date, the occurrence, fate and toxicity of metal-based NPs in the environment is under investigated. Their unique physicochemical, biological and optical properties, responsible for their advantageous application, make them intrinsically different from their bulk counterpart, raising the issue of their potential toxic specificity or "nanosize effect". The aim of this study was to investigate copper bioaccumulation, subcellular distribution and toxic effect in the marine benthic species Scrobicularia plana exposed to two forms of sediment-associated copper, as nanoparticles (CuO NPs) and as soluble ions (CuCl₂). Results showed that the exposure to different copper forms activated specific organism's metal handling strategies. Clams bioaccumulated soluble copper at higher concentrations than those exposed to sediment spiked with CuO NPs. Moreover, CuO NPs exposure elicited a stronger detoxification response mediated by a prompt mobilization of CuO NPs to metal-containing granules as well as a delayed induction of MT-like proteins, which conversely, sequestered soluble copper since the beginning of the exposure at levels significantly different from the control. Eventually, exposure to high concentrations of either copper form led to the same acute toxic effect (100% mortality) but the outcome was delayed in bivalves exposed to CuO NPs suggesting that the mechanisms underlying toxicity were copper form-specific. Indeed, while most of soluble copper was associated to the mitochondrial fraction suggesting an impairment of the ATP synthesis capacity at mitochondrial level, CuO NPs toxicity was most likely caused by the oxidative stress mediated by their bioaccumulation in the enzymatic and mitochondrial metabolically available fractions.

A meta-analysis framework to assess the role of units in describing nanoparticle toxicity

Despite ample research on nanoparticles, their environmental toxicity is still debatable. The lack of consensus is due in part to the challenge of comparing studies because of variability in parameters like test organism, test medium, and duration of experiment. However, the unit used to compare the toxicology of nanoparticles is one variable that experimentalists can control. Traditionally, mass per volume is the most common unit used to make comparisons, but there is growing evidence that alternative units such as surface area per volume or particles per volume may provide a better and more mechanistic measure of toxicity. Herein, we propose and test a meta-analytic framework to study the effect of units on nanotoxicology using data from the NanoE-Tox database, a freely available database containing 1518 toxicology values from 224 published articles of which 42 records met our basic inclusion criteria. These data were augmented with more recent data published over the past five years as archived by the Web of Science citation index. An additional 27 records from 1676 papers met the inclusion criteria and were also included in the analysis. The meta-analysis framework measures the degree of heterogeneity for each of three units (grams/L, particles/L, surface area/L) grouped by the type of test organism, particle chemistry, and manner in which a nanoparticle's size was measured (e.g., nominal particle size reported by the manufacturer vs. measurement of size for particles suspended in the liquid medium used in a subsequent toxicity experiment). The result of the meta-analysis reveals that surface area per volume reduces the heterogeneity in the Ag crustacean subgroup when nanoparticle size was measured in the test medium, and the ZnO crustacean subgroup when nanoparticle size was measured out the test medium and may therefore be a more appropriate estimate of the toxicity of soluble nanoparticles. No subgroups in our analysis showed a reduction in heterogeneity for particles per volume in either soluble or insoluble nanoparticles. The lack of conclusion on insoluble nanoparticles was not due to a limitation of our meta-analysis but rather highlights a critical deficiency in the primary literature. The majority of published studies fail to report common measures of error that are essential for further analysis (i.e. error of the measured nanoparticle size and/or interoperable error of the measured half-maximal concentration of the toxic endpoint). If future nanotoxicity studies report such error, as they should, then the framework of our meta-analysis could be used more broadly to provide a simple, statistically rigorous way to assess the role of units on the toxicity of nanoparticles.

Progress on the usage of the rotifer Brachionus plicatilis in marine ecotoxicology: A review

The rotifer, Brachionus plicatilis, is a widely used model species in marine ecotoxicology for evaluating pollutions, toxins, and harmful algae. In this paper, the marine ecotoxicology of Brachionus plicatilis was reviewed, including toxicity measurements of harmful algae species and environmental stresses. In addition, marine pollution involving pesticides, heavy metals, drugs, petroleum, and petrochemicals were addressed. Methods for measuring toxicity were also discussed. The standard acute lethal assay and the chronic population dynamics test were indicated as common methods of toxicity evaluating using B. plicatilis. Research on other biomarkers, such as behaviour, enzyme activity, or gene expression, are also reported here, with potential applications for fast detection or the scientific exploration of underlying molecular mechanisms. It is suggested that the methods selected should reflect the experimental purpose. Additionally, series assays should be conducted for comprehensive evaluation of ecotoxicity as well as to elucidate the correct mechanisms. Genetic methods, such as transcriptomics, were suggested as useful tools for exploring the toxicity mechanism using the rotifer B. plicatilis.

Chronic sublethal effects of ZnO nanoparticles on Tigriopus fulvus (Copepoda, Harpacticoida)

This study investigated for the first time the effects of ZnO nanoparticle (NP) chronic exposure (28 days) on Tigriopus fulvus. Acute toxicity (48 h) of three Zn chemical forms was assessed as well including the following: (a) ZnO nanoparticles (NPs), (b) Zn2+ from ZnO NP suspension after centrifugation (supernatant) and (c) ZnSO4 H2O. Physical-chemical and electronic microscopies were used to characterize spiked exposure media. Results showed that the dissolution of ZnO NPs was significant, with a complete dissolution at lowest test concentrations, but nano- and micro-aggregates were always present. Acute test evidenced a significant higher toxicity of Zn2+ and ZnSO4 compared to ZnO NPs. The chronic exposure to ZnO NPs caused negative effects on the reproductive traits, i.e. brood duration, brood size and brood number at much lower concentrations (≥ 100 μg/L). The appearance of ovigerous females was delayed at higher concentrations of ZnO NPs, while the time required for offspring release and the percentage of non-viable eggs per female were significantly increased. ZnO NP subchronic exposure evidenced its ability to reduce T. fulvus individual reproductive fitness, suggesting that ZnO NPs use and release must be carefully monitored. Graphical abstract Graphical Abstract.

Comparative effects of Cu (60-80 nm) and CuO (40 nm) nanoparticles in Artemia salina: Accumulation, elimination and oxidative stress

In this study, nanotoxicity tests were made by exposure of Artemia salina to copper (Cu 60-80 nm) and copper oxide (CuO 40 nm) nanoparticles (NPs) at different concentrations (0.2, 1, 5, 10, 25, and 50 mg/l) during some exposure duration. Characterization of Cu and CuO NPs were performed using Transmission Electron Microscope (TEM), Dynamic Light Scattering (DLS), Zeta Potential, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transformation Infrared (FT-IR) analyzes. In organisms, the accumulation and elimination rates of NPs was determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) analysis and the oxidative stress effects on A. salina were determined by Glutathione (GSH) and Thiobarbituric acid reactive substances (TBARS) analysis methods. Both NPs were found to differ in accumulation and elimination rates at each application time and in parallel with the increase in concentration. In each group, it was determined that ion release increased with application time. The results showed that the accumulation rates in Cu NPs had a tendency to increase at 48 h and to decrease at 72 h in concentrations of 0, 2 and 1 mg/l, respectively. And in the all other concentrations have been seen an increasing trend within the time. In the CuO NPs (40 nm), accumulation rates were a decrease trend at 48th hour and an increase trend at 72nd hour except 10 mg/l concentration. In the 10 mg/l group was an increase trend with the application period. Cu NP, TBARS value increased with increasing concentrations and the highest increase was observed at 24 h of 5 ppm group. The groups showed a tendency to increase-decrease-increase-decrease in TBARS levels in terms of elapsed time (24th, 48th, 72nd hour and elimination) (5 ppm and 10 ppm groups tended to decrease in TBARS level at 72nd hour). TBARS increased with increasing concentration ratios in CuO NPs (40 nm).

Does soil CuO nanoparticles pollution alter the gut microbiota and resistome of Enchytraeus crypticus?

Growing evidence suggests that metallic oxide nanoparticles can pose a severe risk to the health of invertebrates. Previous attention has been mostly paid to the effects of metallic oxide nanoparticles on the survival, growth and physiology of animals. In comparison, the effects on gut microbiota and incidence of antibiotic resistance genes (ARGs) in soil fauna remain poorly understood. We conducted a microcosm study to explore the responses of the non-target soil invertebrate Enchytraeus crypticus gut microbiota and resistomes to copper oxide nanoparticles (CuO NPs) and copper nitrate by using bacterial 16S rRNA gene amplicons sequencing and high throughput quantitative PCR. The results showed that exposure to Cu²⁺ resulted in higher bioaccumulation (P < 0.05) and lower body weight and reproduction (P < 0.05) of Enchytraeus crypticus than exposure to CuO NPs. Nevertheless, exposure to CuO NPs for 21 days markedly increased the alpha-diversity of the gut microbiota of Enchytraeus crypticus (P < 0.05) and shifted the gut microbial communities, with a significant decline in the relative abundance of the phylum Planctomycetes (from 37.26% to 19.80%, P < 0.05) and a significant elevation in the relative abundance of the phyla Bacteroidetes, Firmicutes and Acidobacteria (P < 0.05). The number of detected ARGs in the Enchytraeus crypticus gut significantly decreased from 45 in the Control treatment to 16 in the Cu(NO₃)₂ treatment and 20 in the CuO NPs treatment. The abundance of ARGs in the Enchytraeus crypticus gut were also significantly decreased to 38.48% when exposure to Cu(NO₃)₂ and 44.90% when exposure to CuO NPs (P < 0.05) compared with the controls. These results extend our understanding of the effects of metallic oxide nanoparticles on the gut microbiota and resistome of soil invertebrates.

Short-term exposure to low concentrations of copper oxide nanoparticles can negatively impact the ecological performance of a cosmopolitan freshwater fungus

In the past few decades, the use of nano-based products has been expanding, subsequently increasing the risk of aquatic contamination by nanoparticles (NPs). Consequently, it is important to assess the potential risks of environmentally realistic concentrations of NPs. Leaf litter decomposition, a fundamental ecological process in headwater streams, is governed mainly by fungi. In this study, copper oxide nanoparticles (CuO NPs) were synthesised, and the influence of short term exposure to low concentrations of copper oxide nanoparticles on leaf litter decomposition and fungal reproduction (sporulation) was assessed. A cosmopolitan aquatic fungal decomposer species Articulospora tetracladia was used to assess litter decomposition upon exposure to CuO NPs (0.00, 0.04, 0.08 and 0.12 mg L-1) for a short time period (1, 2, 3 and 4 days). Concentrations and exposure time of NPs affected both leaf litter decomposition and sporulation. A significant difference in leaf litter decomposition and fungal sporulation was observed between the control (0.0 mg L-1) and all concentrations tested but not between 0.04, 0.08 and 0.12 mg L-1 of NPs. All the exposure time points (1, 2, 3 and 4 days) had a significant impact on sporulation; however a significant difference in leaf litter mass loss was seen between all time points except for between 2 and 3 days. Overall, our study provides a novel insight into the potential risk of short-term exposure to environmentally realistic concentrations of CuO NPs on the ecological performance of a cosmopolitan freshwater fungus.

Recent advances in the biotoxicity of metal oxide nanoparticles: Impacts on plants, animals and microorganisms

The contact between metal oxide nanoparticles (NPs) and human is more and more close with their wide applications. The inputs of metal oxide NPs to the environment are also growing every year, which causes potential environmental and human health risks. They are toxic to animals, microorganisms and plants at high concentrations, and they show different mechanisms of toxicity to different species. In addition, under complex environmental conditions, their toxic effects are often unpredictable. We have integrated the recent studies on the biotoxicity of metal oxide NPs from 2015-present, and clarified their toxic mechanism, as well as the toxic harm. It lays a foundation for further studying the toxicity and ecological risk of metal oxide NPs.

CuO nanoparticle penetration through intact and damaged human skin

Trans-dermal in vitro study of CuO nanoparticles in contact with intact and damaged human skin using a Franz cell model.

The nanotechnology among US: are metal and metal oxides nanoparticles a nano or mega risk for soil microbial communities?

Metal nanoparticles and metal oxides nanoparticles (MNPs/MONPs) have been widely included in a great diversity of products and industrial applications and they are already a part of our everyday life. According to estimation studies, their production is expected to increase exponentially in the next few years. Consequently, soil has been suggested as the main sink of MNPs/MONPs once they are deliberately or accidentally released into the environment. The potential negative perturbations that may result on soil microbial communities and ecological processes are resulting in concerns. Several nano-toxicological studies of MNPs/MONPs, reported so far, have focused on aquatic organisms, animals, and soil invertebrates. However, during recent years, the studies have been oriented to understand the effects of MNPs/MONPs on microbial communities and their interaction with soil components. The studies have suggested that MNPs/MONPs are one of the most toxic type to soil biota, amongst different types of nanomaterials. This may threaten soil health and fertility, since microbial communities are known to support important biological processes and ecosystem services such as the nutrient cycling, whereby their protection against the environmental pollution is imperative. Therefore, in this review we summarize the actual knowledge available from the last five years (2013-2018) and gaps about the potential negative, positive or neutral effects produced on soil by different classes of MNPs/MONPs. A particular emphasis has been placed on the associated soil microorganisms and biological processes. Finally, perspectives about future research are discussed.

Copper Oxide Nanoparticles Cause a Dose-Dependent Toxicity via Inducing Reactive Oxygen Species in Drosophila

Copper oxide nanoparticles (CuONPs) have attracted considerable attention, because of their biocide potential and capability for optical imaging, however CuONPs were shown to be highly toxic in various experimental model systems. In this study, mechanism underlying CuONP-induced toxicity was investigated using Drosophila as an in vivo model. Upon oral route of administration, CuONPs accumulated in the body, and caused a dose-dependent decrease in egg-to-adult survivorship and a delay in development. In particular, transmission electron microscopy analysis revealed CuONPs were detected inside the intestinal epithelial cells and lumen. A drastic increase in apoptosis and reactive oxygen species was also observed in the gut exposed to CuONPs. Importantly, we found that inhibition of the transcription factor Nrf2 further enhances the toxicity caused by CuONPs. These observations suggest that CuONPs disrupt the gut homeostasis and that oxidative stress serves as one of the primary causes of CuONP-induced toxicity in Drosophila.

Cytotoxicity and cellular mechanisms of toxicity of CuO NPs in mussel cells in vitro and comparative sensitivity with human cells

There is a need to assess human and ecosystem health effects of copper oxide nanoparticles (CuO NPs), extensively used in many industrial products. Here, we aimed to determine the cytotoxicity and cellular mechanisms involved in the toxicity of CuO NPs in mussel cells (hemocytes and gill cells) in parallel with exposures to ionic Cu and bulk CuO, and to compare the sensitivity of mussel primary cells with a well-established human cell line (pulmonary TT1 cells). At similar doses, CuO NPs promoted dose-dependent cytotoxicity and increased reactive oxygen species (ROS) production in mussel and human cells. In mussel cells, ionic Cu was more toxic than CuO NPs and the latter more than bulk CuO. Ionic Cu and CuO NPs increased catalase and acid phosphatase activities in both mussel cells and decreased gill cells Na-K-ATPase activity. All Cu forms produced DNA damage in hemocytes, whereas in gill cells only ionic Cu and CuO NPs were genotoxic. Induction of the MXR transport activity was found in gill cells exposed to all forms of Cu and in hemocytes exposed to ionic Cu and CuO NPs. Phagocytosis increased only in hemocytes exposed to CuO NPs, indicating a nanoparticle-specific immunostimulatory effect. In conclusion, toxicity of CuO NPs is driven by ROS in human and mussel cells. Mussel cells respond to CuO NP exposure by triggering an array of defensive mechanisms.

Cytotoxicity and genotoxicity of CuO nanoparticles in sea urchin spermatozoa through oxidative stress

Copper oxide nanoparticles (CuO NPs) are extensively used in various industrial and commercial applications. Despite their wide application may lead to the contamination of marine ecosystem, their potential environmental effects remain to be determined. Toxicity assessment studies have primarily focused on investigating the effects of CuO NPs on fertilization success and embryo development of different sea urchin species while the impact on sperm quality have never been assessed. In this line, this study aims to assess the effects of CuO NPs on the spermatozoa of the sea urchin Paracentrotus lividus. After sperm exposure to CuO NPs, biomarkers of sperm viability, cytotoxicity, oxidative stress, and genotoxicity as well as morphology were evaluated. Results showed that CuO NPs exposure decreased sperm viability, impaired mitochondrial activity and increased the production of reactive oxygen species (ROS) and lipid peroxidation. Furthermore, CuO NPs exposure caused DNA damage and morphological alterations. Together with the antioxidant rescue experiments, these results suggest that oxidative stress is the main driver of CuO NP spermiotoxic effects. The mechanism of toxicity is here proposed: the spontaneous generation of ROS induced by CuO NPs and the disruption of the mitochondrial respiratory chain lead to production of ROS that, in turn, induce lipid peroxidation and DNA damage, and result in defective spermatozoa up to induce sperm cytotoxicity. Investigating the effects of CuO NPs on sea urchin spermatozoa, this study provides valuable insights into the mechanism of reproductive toxicity induced by CuO NPs.

Copper oxide nanoparticles induce the transcriptional modulation of oxidative stress-related genes in Arbacia lixula embryos

Copper oxide nanoparticles (CuO NPs) are widely used in various industrial applications, i.e. semiconductor devices, batteries, solar energy converter, gas sensor, microelectronics, heat transfer fluids, and have been recently recognized as emerging pollutants of increasing concern for human and marine environmental health. Therefore, the toxicity of CuO NPs needs to be thoroughly understood. In this study, we evaluated the potential role of oxidative stress in CuO NP toxicity by exploring the molecular response of Arbacia lixula embryos to three CuO NP concentrations (0.7, 10, 20 ppb) by investigating the transcriptional patterns of oxidative stress-related genes (catalase and superoxide dismutase) and metallothionein, here cloned and characterized for the first time. Time- and concentration-dependent changes in gene expression were detected in A. lixula embryos exposed to CuO NPs, up to pluteus stage (72 h post-fertilization, hpf), indicating that oxidative stress is one of the toxicity mechanisms for CuO NPs. These findings provide new insights into the comprehension of the molecular mechanisms underlying copper nanoparticle toxicity in A. lixula sea urchin and give new tools for monitoring of aquatic areas, thus corroborating the suitability of this embryotoxicity assay for future evaluation of impacted sites.

Salinity-Based Toxicity of CuO Nanoparticles, CuO-Bulk and Cu Ion to Vibrio anguillarum

Bacteria are used in ecotoxicology for their important role in marine ecosystems and their quick, reproducible responses. Here we applied a recently proposed method to assess the ecotoxicity of nanomaterials on the ubiquitous marine bacterium Vibrio anguillarum, as representative of brackish and marine ecosystems. The test allows the determination of 6-h EC₅₀ in a wide range of salinity, by assessing the reduction of bacteria actively replicating and forming colonies. The toxicity of copper oxide nanoparticles (CuO NPs) at different salinities (5-20-35 ‰) was evaluated. CuSO₄ 5H₂O and CuO bulk were used as reference toxicants (solubility and size control, respectively). Aggregation and stability of CuO NP in final testing dispersions were characterized; Cu²⁺ dissolution and the physical interactions between Vibrio and CuO NPs were also investigated. All the chemical forms of copper showed a clear dose-response relationship, although their toxicity was different. The order of decreasing toxicity was: CuSO₄ 5H₂O > CuO NP > CuO bulk. As expected, the size of CuO NP aggregates increased with salinity and, concurrently, their toxicity decreased. Results confirmed the intrinsic toxicity of CuO NPs, showing modest Cu²⁺ dissolution and no evidence of CuO NP internalization or induction of bacterial morphological alterations. This study showed the V. anguillarum bioassay as an effective tool for the risk assessment of nanomaterials in marine and brackish environments.