Comparative toxicity of CuO nanoparticles and CuSO4 in rainbow trout

"From shadows to shores"-quantitative analysis of CuO nanoparticle-induced apoptosis and DNA damage in fish erythrocytes: A multimodal approach combining experimental, image-based quantification, docking and molecular dynamics

The usage of copper (II) oxide nanoparticles (CuO NPs) has significantly expanded across industries and biomedical fields. However, the potential toxic effects on non-target organisms and humans lack comprehensive understanding due to limited research on molecular mechanisms. With this study, by combining the 96 h in vivo exposure of crucian carp fish, Carassius carassius, to sub-lethal CuO NPs doses (0.5 and 1 mg/dL) with image-based quantification, and docking and molecular dynamics approaches, we aimed to understand the mechanism of CuO NPs-induced cyto-genotoxicity in the fish erythrocytes. The results revealed that both doses of copper NPs used were toxic to erythrocytes causing oxidative stress response and serious red blood cell morphological abnormalities, and genotoxicity. Docking and 10-ns molecular dynamics confirmed favorable interactions (ΔG = -2.07 kcal mol-1) and structural stability of Band3-CuO NP complex, mainly through formation of H-bonds, implying the potential of CuO NPs to induce mitotic nuclear abnormalities in C. carassius erythrocytes via Band3 inhibition. Moreover, conventional and multiple ligand simultaneous docking with DNA revealed that single, double and triple CuO NPs bind preferentially to AT-rich regions consistently in the minor grooves of DNA. Of note, the DNA-binding strength subtantially increased (ΔG = -2.13 kcal mol-1, ΔG = -4.08 kcal mol-1, and ΔG = -6.03 kcal mol-1, respectively) with an increasing number of docked CuO NPs, suggesting that direct structural perturbation on DNA could also count for the molecular basis of in-vivo induced DNA damage in C. carassius erythrocytes. This study introduces the novel term "erythrotope" to describe comprehensive red blood cell morphological abnormalities. It proves to be a reliable and cost-effective biomarker for evaluating allostatic erythrocyte load in response to metallic nanoparticle exposure, serving as a distinctive fingerprint to assess fish erythrocyte health and physiological fitness.

Plant based synthesis of silver nanoparticles, antimicrobial efficiency, and toxicological assessment using freshwater fish (Cyprinus carpio)

Silver nanoparticles (AgNPs) are widely used and have various applications, including medicine, electronics, and textiles. However, their increasing use raises concern about their potential environmental impact, particularly on aquatic organisms, such as fish, which are the primary consumers of aquatic environments and can be exposed to AgNPs through various routes. For this purpose, the leaves of the plant species Bellis perennis were used as a reductive agent to convert silver nitrate into AgNPs, to assess its toxicity against fish. Well-dispersed and undersized AgNPs were obtained and confirmed using analytical techniques, including Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Moreover, the AgNPs have shown significant antibacterial activity against Aeromonas hydrophila (25.71 ± 0.63) and Vibrio harveyi (22.39 ± 0.29). In addition, the toxicity of the obtained AgNPs was assessed by exposing Cyprinus carpio to various concentrations, including 0.06, 0.1, and 0.2 mg/L. The findings revealed that the AgNPs were significantly accumulated in the intestine, followed by the gills, liver, muscles, kidney, and brain. This bioaccumulation led to histological alterations and destruction in the villi of the intestine, regeneration of liver cells, and degeneration of the gill lamella. RESEARCH HIGHLIGHTS: Plants based synthesis of AgNPs is mostly considered as eco-friendly A significant antibacterial activity was obtained The plant mediated AgNPs were found less toxic The AgNPs was profoundly accumulated and causes histological alterations.

Klebsiella pneumoniae in the intestines of Musca domestica larvae can assist the host in antagonizing the poisoning of the heavy metal copper

BACKGROUND

Musca domestica larvae are common saprophytes in nature, promoting the material-energy cycle in the environment. However, heavy metal pollution in the environment negatively affects their function in material circulation. Our previous research found that some intestinal bacteria play an important role in the development of housefly, but the responses of microbial community to heavy metal stresses in Musca domestica is less studied.

RESULTS

In this study, CuSO4, CuSO4-Klebsiella pneumoniae mixture and CuSO4-K. pneumoniae phage mixture were added to the larval diet to analyze whether K. pneumoniae can protect housefly larvae against Cu2+ injury. Our results showed that larval development was inhibited when were fed with CuSO4, the bacterial abundance of Providencia in the intestine of larvae increased. However, the inhibition effects of CuSO4 was relieved when K. pneumoniae mixed and added in larval diets, the abundance of Providencia decreased. Electron microscope results revealed that K. pneumoniae showed an obvious adsorption effect on copper ion in vitro.

CONCLUSIONS

Based on the results we assume that K. pneumoniae could adsorb Cu2+, reduce Cu2+ impact on gut community structure. Our study explains the role of K. pneumoniae antagonizing Cu2+, which could be applied as a probiotic to saprophytic bioantagonistic metal contamination.

Effects of CuO nanoparticles in composted sewage sludge on rice-soil systems and their potential human health risks

The release of metal-based nanoparticles (MNPs) into sewage systems is worrisome due to their potential impact on crop-soil systems that are amended with sewage sludge. This study aimed to investigate the effects of copper oxide nanoparticles (CuO NPs) in composted sewage sludge (CSS) on rice-soil systems and to assess the health risks associated with consuming CuO NP-contaminated rice produced by CSS amendment. CSS was treated with three doses of CuO NPs, resulting in Cu levels below the sludge limits (1500 mg Cu kg-1) for reuse as a soil amendment. Results showed that CuO NPs in CSS at environmentally acceptable levels had no negative effect on rice growth and yield. In fact, they enhanced biomass production, tillering capacity, and soil fertility by increasing N and K levels in the soil. In addition, CuO NPs in CSS (450-1450 mg Cu kg-1) promoted the accumulation of macro- and micro-minerals in rice grains, thereby improving the nutritional value of rice. However, Cu contamination in CSS led to elevated levels of toxic metals, especially As, in rice grains, posing potential health risks to both adults and children. In the presence of higher CuO NPs contamination in CSS, the hazard quotient of As exceeded one, indicating an increased risks of toxic metal exposure via rice consumption. This study raises concerns about potential long-term threats to human health posed by MNPs contamination in CSS and highlights the need to reevaluate the permissible limits of hazardous elements in sludge to ensure its safe reuse in agriculture.

Metabolomics and mass spectrometry imaging reveal the chronic toxicity of indoxacarb to adult zebrafish (Danio rerio) livers

Indoxacarb is a widely used insecticide in the prevention and control of agricultural pests, whereas its negative effects on non-target organisms remain largely unclear. Herein, we demonstrated the integrated metabolomics and mass spectrometry imaging (MSI) methods to investigate the chronic exposure toxicity of indoxacarb at environmentally relevant concentrations in adult zebrafish (Danio rerio) liver. Results showed that movement behaviors of zebrafish can be affected and catalase (CAT), glutamic oxalacetic transaminase (GOT), and glutamic pyruvic transaminase (GPT) activities were significantly increased after indoxacarb exposure for 28 days. Pathological analysis of zebrafish livers also showed that cavitation and pathological reactions occur. Metabolomics results indicated that metabolic pathways of zebrafish liver could be significantly affected by indoxacarb, such as tricarboxylic acid (TCA) cycle and various amino acid metabolisms. MSI results revealed the spatial differentiation of crucial metabolites involved in these metabolic pathways within zebrafish liver. Taken together, these integrated MSI and metabolomics results revealed that the toxicity of indoxacarb arises from metabolic pathways disturbance, which resulted in the decrease of liver detoxification ability. These findings will promote the current understanding of pesticide risks and metabolic disorders in zebrafish liver, which provide new insights into the environmental risk assessment of insecticides on aquatic organisms.

Anti-capsular activity of CuO nanoparticles against Acinetobacter baumannii produce efflux pump

Copper oxide nanoparticles are modern kinds of antimicrobials, which may get a lot of interest in the clinical application. This study aimed to detect the anti-capsular activity of CuO nanoparticles against Acinetobacter baumannii produce efflux pump. Thirty-four different clinical A. baumannii isolates were collected and identified by the phenotypic and genetic methods by the recA gene as housekeeping. Antibiotic sensitivity and biofilm-forming ability, capsular formation were carried out. The effect of CuO nanoparticles on capsular isolates was detected, the synergistic effects of a combination CuO nanoparticles and gentamicin against A. baumannii were determined by micro broth checkerboard method, and the effect of CuO nanoparticles on the expression of ptk, espA and mexX genes was analyzed. Results demonstrated that CuO nanoparticles with gentamicin revealed a synergistic effect. Gene expression results show reducing the expression of these capsular genes by CuO nanoparticles is major conduct over reducing A. baumannii capsular action. Furthermore, results proved that there was a relationship between the capsule-forming ability and the absence of biofilm-forming ability. As bacterial isolates which were negative biofilm formation were positive in capsule formation and vice versa. In conclusion, CuO nanoparticles have the potential to be used as an anti-capsular agent against A. baumannii, and their combination with gentamicin can enhance their antimicrobial effect. The study also suggests that the absence of biofilm formation may be associated with the presence of capsule formation in A. baumannii. These findings provide a basis for further research on the use of CuO nanoparticles as a novel antimicrobial agent against A. baumannii and other bacterial pathogens, also to investigate the potential of CuO nanoparticles to inhibit the production of efflux pumps in A. baumannii, which are a major mechanism of antibiotic resistance.

Influences of l-ascorbic acid on cytotoxic, biochemical, and genotoxic damages caused by copper II oxide nanoparticles in the rainbow trout gonad cells-2

In parallel with the raising use of copper oxide nanoparticles (CuO NPs) in various industrial and commercial practices, scientific reports on their release to the environment and toxicity are increasing. The toxicity of CuO NPs is mostly based on their oxidative stress. Therefore, it is necessary to investigate the efficacy of well-known therapeutic agents as antioxidants against CuO NPs damage. This study aimed to investigate the mechanism of this damage and to display whether l-ascorbic acid could preserve against the cell toxicities induced by CuO NPs in the rainbow trout gonad cells-2 (RTG-2). While CuO NPs treatment significantly diminished cell viability, the l-ascorbic acid supplement reversed this. l-ascorbic acid treatment reversed the changes in expressions of sod1, sod2, gpx1a, and gpx4b genes while playing a supportive role in the changes in the expression of the cat gene induced by CuO NPs treatment. Moreover, CuO NPs treatment caused an upregulation in the expressions of growth-related genes (gh1, igf1, and igf2) and l-ascorbic acid treatment further increased these effects. CuO NPs treatment significantly up-regulated the expression of the gapdh gene (glycolytic enzyme gene) compared to the control group, and l-ascorbic acid treatment significantly down-regulated the expression of the gapdh gene compared to CuO NPs treatment. The genotoxicity test demonstrated that l-ascorbic acid treatment increased the genotoxic effect caused by CuO NPs by acting as a co-mutagen. Based on the findings, l-ascorbic acid has the potential to be sometimes inhibitory and sometimes supportive of cellular mechanisms caused by CuO NPs.

Toxicological risks of SDHIs and QoIs to zebrafish (Danio rerio) and the corresponding poisoning mechanism

Quinone outside inhibitor fungicides (QoIs) and succinate dehydrogenase inhibitor fungicides (SDHIs) were classified as highly or moderately toxic to nontarget aquatic organisms, which deterred their application in paddy scenario. Currently, the mechanism of toxicity regarding which factors govern their risk ranking in fish species are not fully explored. In this study, adult zebrafish were exposed to four QoIs (pyraclostrobin, trifloxystrobin, kresoxim-methyl, and azoxystrobin) and three SDHIs (isopyrazam, thifluzamide, and boscalid) to assess its acute toxicity and effects on tissue accumulation and gill injury. The results showed that the overall toxicity level was in the order of QoIs > SDHIs, whereas the order of accumulation capacity was SDHIs > QoIs. Seven mitochondrial respiratory inhibitors exposure induced serious histological damage in the gills, including aneurism, curling, telangiectasia and swelling, and caused mitochondrial dysfunction and weaker complex II and III activities. The correlation between their acute toxicities and in vitro gill cytotoxicity was significant (R = 0.868), whereas the bioaccumulation level was not markedly associated with their 96h-LC₅₀ values in zebrafish (R = -0.686), indicating the degree of target organ (gill) injury may be the decisive factor that governs the risk grade of respiratory inhibitors in fish. Additionally, the docking positions and binding energies of fungicides with the target proteins may be responsible for their differential branchial damage. These results offer a point of reference and theoretical support for the design of fungicides and appropriate formulations with improved environmental safety that could broaden their application scenario.

An Investigation on Freshwater Fish Oreochromis niloticus (Linnaeus, 1758): Assessing Hemotoxic Effects of Different Copper Compounds Used as Nanomaterial or Pesticide

Considering the constant exposure of fish to copper oxide nanoparticles (CuO-NPs) and copper sulphate (CuSO₄) in natural aquatic environments as a result of increased usage of these chemicals in industry, medicine and aquaculture/agriculture over the past few decenniums, the current investigation aimed to reveal their comparative hemotoxic effects on freshwater fish Oreochromis niloticus by measuring hematological and blood oxidative stress biomarkers and Cu levels. Fish were exposed to 0.05 mg/L CuO-NPs and CuSO₄ for 4 and 21 days. Both copper forms decreased erythrocyte, hematocrit, and hemoglobin values, and superoxide dismutase and catalase activities while they elevated glucose-6-phosphate dehydrogenase activity, and glutathione, malondialdehyde and Cu levels. Leukocyte levels and glutathione peroxidase activity did not show any significant change. In a conclusion, the current research demonstrates that CuO-NPs and CuSO₄ for O. niloticus have similar hemotoxic effects, however, CuO-NPs are slightly more toxic than CuSO₄ regarding hematological changes and oxidative stress observed.

Vitamin C suppresses toxicological effects in MO/MФ and IgM+ B cells of Nile tilapia (Oreochromis niloticus) upon copper exposure

Copper (Cu), as an essential micronutrient in human and animal metabolism, easily spreads and excessively accumulates in rearing water, which make it more susceptible to fish farms and threatens the health of aquatic animals. In this issue, the protective effect of vitamin C against oxidative damage caused by copper exposure was studied in monocytes/macrophages (MO/MФ) and IgM⁺ B cells of Nile tilapia (Oreochromis niloticus), the cell types possessing phagocytic activities. The significant increase of ROS level and up-regulation of proinflammatory factors accompanied by depletion of GSH and down-regulation of antioxidative molecules in MO/MФ and IgM⁺ B cells, when stressed with CuO NPs or Cu ions, indicated the induction of oxidative damage due to the toxicological effects with copper exposure. Copper induced cell apoptosis through mitochondrial-dependent pathway in these two cell populations was demonstrated with disruption of mitochondrial membrane potential (ΔΨm) and activation of apoptosis factor. Furthermore, the phagocytic abilities for microspheres and bioparticle uptake significantly decreased in these two cell populations upon CuO NPs or Cu ions; meanwhile, antigen presentation of MO/MФ and antibody production of IgM⁺ B cells were also inhibited. However, vitamin C supplementation reversed all these biochemical indices, as well as cell apoptosis and phagocytic abilities in MO/MФ and IgM⁺ B cells that were induced by CuO NPs or Cu ions. In conclusion, these results revealed that vitamin C exerts cytoprotective effects against oxidative damage through its antioxidant properties and may be of therapeutic use in preventing toxicological effects caused by copper exposure.

Immunotoxic effects of metal-based nanoparticles in fish and bivalves

There is a global research interest in metal nanoparticles (MNPs) due to their diverse applications, rapidly increasing use, and increased presence in the aquatic environment. Currently, most MNPs in the environment are at levels unlikely to cause overt toxicity. Sub-lethal effects that MNPs may induce, notable immunotoxicity, could however have significant health implications. Thus, deciphering the immunological interactions of MNPs with aquatic organisms constitutes a much-needed area of research. In this article, we critically assess the evidence for immunotoxic effects of MNPs in bivalves and fish, as key wildlife sentinels with widely differing ecological niches that are used as models in ecotoxicology. The first part of this review details the properties, fate, and fundamental physicochemical behavior of MNPs in the aquatic ecosystem. We then consider the toxicokinetics of MNP uptake, accumulation, and deposition in fish and bivalves. The main body of the review then focuses on immune reactions in response to MNPs exposure in bivalves and fish illustrating their immunotoxic potential. Finally, we identify major knowledge gaps in our current understanding of the implications of MNPs exposure for immunological functions and the associated health consequences for bivalves and fish, as well as the general lessons learned on the immunotoxic properties of the emerging class of nanoparticulate contaminants in fish and bivalves.

Toxicological damages on copper exposure to IgM+ B cells of Nile tilapia (Oreochromis niloticus) and mitigation of its adverse effects by β-glucan administration

Present investigation was carried out to study toxicological damages of copper exposure and mitigation of its adverse effects with β-glucan administration in IgM⁺ B cells which processes multiple roles similar to macrophages in Nile tilapia (Oreochromis niloticus). IgM⁺ B cells were pretreated with β-glucan (25 μg/mL) for 24 h before exposed to cupric oxide nanoparticles (CuO NPs) or cupric chloride (Cu ions) at the doses of 0, 5, 10, and 20 μg/mL for 24 h, respectively. Our results demonstrated that β-glucan increased reduced glutathione (GSH) to against oxidative damage from CuO NPs and Cu ions exposure in IgM⁺ B cells. The apoptosis process through mitochondrial signaling pathway was depressed in IgM⁺ B cells since the mitochondrial membrane potential (ΔΨm) was protected from copper exposure by β-glucan treatment. Furthermore, the inhibition on phagocytic abilities of IgM⁺ B cells caused by copper exposure could be enhanced with β-glucan treatment via evaluation of microspheres and bioparticles uptake and LPS-induced NO production. Importantly, β-glucan might participate in immunomodulation in IgM⁺ B cells through B cell antigen receptor (BCR) to suppress toxicological effect derived from copper exposure. Taken together, this study provides more information on the toxicological damages in IgM⁺ B cells upon copper exposure and explains the molecular mechanism to reverse adverse effects caused by copper exposure with β-glucan administration.

Polyphenol effects on CuO-nanoparticle-mediated DNA damage, reactive oxygen species generation, and fibroblast cell death

The ability of ten polyphenolic antioxidants to prevent CuO nanoparticle (NPCuO) and H2O2-mediated DNA damage and cytotoxicity was investigated. Five of the polyphenols (MEPCA, PREGA, MEGA, ECG, and EGCG) prevent NPCuO/H2O2-mediated DNA damage (IC50 values of 7.5-800 μM), three have no effect (PCA, VA, and EC), and two (GA and EGC) result in increased DNA damage. Most polyphenols had similar antioxidant/prooxidant activity in the presence of NPCuO or free copper ions. Electron paramagnetic resonance (EPR) spectroscopy of reactive oxygen species (ROS) generated by NPCuO/H2O2 in the presence of representative polyphenols correlate with results of DNA damage studies: in the presence of NPCuO/H2O2, MEPCA prevents ROS formation, VA has no effect on ROS levels, and EGC increases ROS levels. EPR results with CuO nanoparticles washed to remove dissolved copper in solution (wCuO) in the presence of H2O2/ascorbate suggest that MEPCA prevents ROS formation on the nanoparticle surface in addition to preventing ROS formation from dissolved copper. In mouse fibroblast (L929) cells, combining NPCuO with H2O2 results in significantly greater cytotoxicity than observed for either component alone. After 3 h incubation with MEPCA or MEGA, the viability loss in L929 cells induced by NPCuO/H2O2 challenge was significantly rescued at physiologically relevant polyphenol levels (1 μM). These studies show that polyphenols can protect DNA and inhibit cytotoxicity generated by NPCuO under oxidative stress conditions.

β-glucan mitigation on toxicological effects in monocytes/macrophages of Nile tilapia (Oreochromis niloticus) following copper exposure

The protective effect of β-glucan against toxicological effects caused by copper oxide nanoparticles (Cu NPs) and copper ions (Cu ions) were studied in monocytes/macrophages (MO/MФ) of Nile tilapia (Oreochromis niloticus). Our results demonstrated that CuO NPs and Cu ions exposure aroused strong oxidative lesion in MO/MФ by detection of cellular reactive oxygen species (ROS) and reduced glutathione (GSH), as well as identification of several antioxidant-related cytokines. Meanwhile, the serious pro-inflammatory responses were accompanied during the processes of oxidative lesion by TNFα, IL-1β, and IL-6 genes validation. Copper induced MO/MФ underwent apoptosis through mitochondrial signaling pathway by mitochondrial membrane potential (ΔΨm) detection and Bax, Bcl-2, Cyt-c, Apaf-1, Caspase 9, Caspase 3 genes validation. Furthermore, the phagocytic abilities were inhibition in MO/MФ by evaluation of microspheres (0.5 and 1.0 μm beads) and bioparticles (S. agalactiae and A. hydrophila) uptake and LPS-induced NO production. However, β-glucan might participate in immunomodulation through C-type lectin receptor (CLR) and complement receptor 3 (CR3) to suppress pro-inflammatory responses, thereby revered all the copper induced aforementioned adverse effects in MO/MΦ. Taken together, our results provide insights on the mechanisms through β-glucan administration to mitigate toxicological effects of CuO NPs and Cu ions exposure to the MO/MΦ, which will benefit aspects related to fish farming and aquaculture production.

Ion compositions in artificial media control the impact of humic acid on colloidal behaviour, dissolution and speciation of CuO-NP

The toxicity of copper oxide nanoparticles (CuO-NP) strongly depends on their interactions with the surrounding environment, impacting their dissolution and colloidal stability. This behaviour is studied quite extensively for simplified electrolytes, but information on the behaviour of CuO-NP in more complex artificial media are lacking. In our study, we analysed the colloidal behaviour and considered the speciation of CuO-NP in pure water and three artificial media of different complexity which are used in ecotoxicology. Measurements were done over 7 days in the absence and presence of humic acid (HA) as a model organic molecule. In pure water, the addition of HA lowered the zeta potential from +11 to -41 mV, while in all artificial media, it stayed constantly at about -20 mV. The hydrodynamic diameter of CuO-NP remained unaffected by HA in pure water and seawater, while in porewater and especially in freshwater, HA suppressed strong agglomeration. In pure water, HA strongly increased dissolution to the highest observed value (3% of total Cu), while HA reduced dissolution in all artificial media. Speciation calculations revealed that cations from the media competed with Cu from the NP surface for complexing sites of the HA. This competition may have caused the reduced dissolution in the presence of ions. Furthermore, speciation calculations also suggest that ion composition drove agglomeration behaviour rather than ion concentration: agglomeration was high when divalent cations where the major interaction partner and dominant in relative terms. HA may have reduced the relative dominance and thus altered the agglomeration, aligning it in all media. Summarizing, ion composition and the presence of HA strongly drive the dissolution and agglomeration of CuO-NP in artificial media, consequently, analysing complexation can help to predict environmental behaviour and toxicity.

Comparative toxicity of multiple exposure routes of pyraclostrobin in adult zebrafish (Danio rerio)

Pyraclostrobin, one of the most widely used fungicides globally, is highly toxic to aquatic organisms, which restricts its application in paddy fields. Most studies have focused on the molecular mechanism of pyraclostrobin toxicity; however, the exposure routes and target organs of pyraclostrobin in fish are poorly known. Here, we found that the lethal effects of aquatic exposure, head immersion, trunk immersion and oral exposure on the toxicity and accumulation of pyraclostrobin in adult zebrafish were different. The major pathway leading to pyraclostrobin accumulation, followed by high hazard to fish, was crossing over the gill rather than the intestine or skin. Additionally, serious histological abnormalities, mitochondrial dysfunction, energy deficiency and respiratory impairment occurred in the gills, while no overt change was observed in the heart and brain at the organic and cellular levels. This result suggested that the gill is the dominant portal and target organ of pyraclostrobin in fish, a fact that has been further verified by intravenous injection. The differences in the toxicity and translocation factor of crystalline and dissolved pyraclostrobin in fish demonstrated that reducing the concentration in the branchial environment is a vital direction for the future design of an effective toxicity regulation strategy to protect key sites from pyraclostrobin attack.

Investigating the effects of copper sulfate and copper oxide nanoparticles in Nile tilapia (Oreochromis niloticus) using multiple biomarkers: the prophylactic role of Spirulina

Copper has toxic effects in fish, whereas the cyanobacterium Spirulina reportedly has protective effects against metal toxicity in various animal species. The current study, therefore, aimed to investigate the prophylactic role of Spirulina platensis against the effects of copper sulfate (CuSO4) and copper oxide nanoparticles (CuO-NPs) in Nile tilapia (Oreochromis niloticus). Biochemical, antioxidant, erthyron profile and histopathological endpoints were assessed after for 15 days of exposure in five separate treatment groups: (1) fish pre-fed the normal diet (control), (2) fish pre-fed the normal diet and exposed to 15 mg/L of CuSO4, (3) fish pre-fed the normal diet augmented with 0.25% Spirulina and exposed to 15 mg/L of CuSO4, (4) fish pre-fed the normal diet and exposed to 15 mg/L of CuO-NPs, and (5) fish pre-fed the normal diet augmented with 0.25% Spirulina and exposed to 15 mg/L CuO-NPs. Exposure to CuSO4 or CuO-NPs significantly increased superoxide dismutase and catalase activities in fish, as well as serum total protein, glucose, aspartate aminotransferase, alanine aminotransferase, creatinine, and uric acid concentrations. In contrast, most hematological indices in fish significantly decreased after CuSO4 or CuO-NPs exposure. Moreover, CuSO4 and CuO-NPs caused a significant increase in the percentage of poikilocytosis and nuclear abnormalities of red blood cells, as well as histopathological changes in the brain, liver, intestine, and kidneys. Importantly, Spirulina supplementation mitigated against physiological disruption caused by CuSO4 or CuO-NPs.

A critical review on genotoxicity potential of low dimensional nanomaterials

Low dimensional nanomaterials (LDNMs) have earned attention among researchers as they exhibit a larger surface area to volume and quantum confinement effect compared to high dimensional nanomaterials. LDNMs, including 0-D and 1-D, possess several beneficial biomedical properties such as bioimaging, sensor, cosmetic, drug delivery, and cancer tumors ablation. However, they threaten human beings with the adverse effects of cytotoxicity, carcinogenicity, and genotoxicity when exposed for a prolonged time in industry or laboratory. Among different toxicities, genotoxicity must be taken into consideration with utmost importance as they inherit DNA related disorders causing congenital disabilities and malignancy to human beings. Many researchers have performed NMs' genotoxicity using various cell lines and animal models and reported the effect on various physicochemical and biological factors. In the present work, we have compiled a comparative study on the genotoxicity of the same or different kinds of NMs. Notwithstanding, we have included the classification of genotoxicity, mechanism, assessment, and affecting factors. Further, we have highlighted the importance of studying the genotoxicity of LDNMs and signified the perceptions, future challenges, and possible directives in the field.

Metal oxide nanoparticles and polycyclic aromatic hydrocarbons alter nanoplastic's stability and toxicity to zebrafish

Co-occurrence of nanoplastics (NPs) with metal oxide nanoparticles (nMOx) and polycyclic aromatic hydrocarbons (PAHs) have been widely reported. However, there is a scarcity of information on their interactions and combined toxic effects. In this study, we used two different sized NPs [55 nm (NP1) and 100 nm (NP2)] to understand the effect of nMOx (nCuO and nZnO) and PAHs [chrysene (Chr) and fluoranthene (Flu)] on NPs' stability and toxicity to zebrafish. Results revealed that increasing the concentration of nMOx, zeta-potential increased, and charge reversal was observed in NPs suspension while PAH produced no major changes. Aggregation kinetics performed with nMOx exhibited higher aggregation of NPs in presence of NaCl that alleviated critical coagulation concentration. NP1 stabilized the size of otherwise unstable nMOx suspension in the tap-water for a longer period, whereas, aggregation was observed with NP2. The in vivo comet assay results showed that NP1 was more genotoxic than NP2 owing to their lower size. Interestingly the DNA damage was highest in NPs+nMOx followed by nMOx and NPs. Unlike nMOx, Chr/Flu+NPs showed reduced DNA damage as compared to NPs or PAH alone. Alteration in catalase activity and lipid peroxidation value indicated oxidative stress in all exposure groups.

The specification of zebrafish (Danio rerio) heart electrocardiogram index characteristic responses to different types of pollutants

Water quality was highly affected by common pollutants. Metals, pesticides and small molecules are ubiquitous pollutants. Advancement in engineering technology (computer-based monitoring systems) increased the efficiency of quantifying toxicity of different chemicals in an organism. The cardiovascular system reflects internal and external stress of an organism, and electrocardiogram (ECG) data reliably measure external stress. As ECG data can accurately reflect the physiological conditions of organisms, and zebrafish (Danio rerio) are considered to be good models for cardiovascular research, it is hypothesized that ECG parameters of zebrafish could indicate the toxicity of water-borne chemicals. To achieve this, we treated zebrafish with different concentrations of target chemicals (CuSO₄, C₁₀H₁₉O₆PS₂ and NH₄Cl) for 48 h and ECG data were measured. P-wave, R-wave, T-wave, PR-interval, QRS-complex and QT-interval data were the focus of this study. The results of self-organizing maps and Pearson correlation analysis indicate that the QRS-complex can be used as an indicator for CuSO₄ stress. The QT-interval could be used to assess the C₁₀H₁₉O₆PS₂ stress. The QT-interval and P-wave can be used to evaluate the NH₄Cl stress. Responses of zebrafish ECG parameters were identical with other vertebrate model, and were specific to toxicant types. It is proved that zebrafish heart ECG index could be used as a potential indicator in early detection of environmental stress.

Dietary uptake and effects of copper in Sticklebacks at environmentally relevant exposures utilizing stable isotope-labeled 65CuCl2 and 65CuO NPs

Copper oxide nanoparticles (CuO NPs) accumulating in sediment can be taken up by invertebrates that serve as prey for fish. Thus, it is likely that the latter are exposed to CuO NPs via the gut. However, to this day it is unknown if CuO NPs can be taken up via the gastrointestinal tract and if and in which tissues/organs they accumulate. To address this knowledge gap, we synthesized CuO NPs enriched in the stable isotope ⁶⁵Cu and incorporated them at low concentration (5 μg ⁶⁵Cu g^-1 ww food) into a practical diet prepared from worm homogenate, which was then fed to Three-spined Stickleback (Gasterosteus aculeatus) for 16 days. For comparison, fish were exposed to a diet spiked with a ⁶⁵CuCl₂ solution. Background Cu and newly taken up ⁶⁵Cu in fish tissues/organs including gill, stomach, intestine, liver, spleen, gonad and carcass and feces were quantified by ICP-MS. In addition, expression levels of genes encoding for proteins related to Cu uptake, detoxification and toxicity (ctr-1, gcl, gr, gpx, sod-1, cat, mta and zo-1) were measured in selected tissues using RT-qPCR. The obtained results showed that feces of fish fed ⁶⁵CuO NP-spiked diet contained important amounts of ⁶⁵Cu. Furthermore, there was no significant accumulation of ⁶⁵Cu in any of the analyzed internal organs, though ⁶⁵Cu levels were slightly elevated in liver. No significant modulation in gene expression was measured in fish exposed to ⁶⁵CuO NP-spiked diet, except for metallothionein, which was significantly upregulated in intestinal tissue compared to control fish. Altogether, our results suggests that dietary absorption efficiency of CuO NPs, their uptake across the gastrointestinal barrier into the organism, and effects on Cu-related genes is limited at low, environmentally relevant exposure doses (0.2 μg ⁶⁵Cu ^-1 fish ww day^-1).

Antibacterial and cytotoxic evaluation of copper and zinc oxide nanoparticles as a potential disinfectant material of connections in implant provisional abutments: An in-vitro study

OBJECTIVE

This study evaluates the antibacterial activity against mono and multispecies bacterial models and the cytotoxic effects of zinc oxide and copper nanoparticles(ZnO-NPs/Cu-NPs) in cell cultures of human gingival fibroblasts(HGFs).

DESIGN

The antibacterial activities of ZnO-NPs and Cu-NPs against 4 bacteria species were tested according to their minimum inhibitory concentrations(MICs) and against mature multispecies anaerobic model by spectral confocal laser scanning microscopy. The viabilities and cytotoxic effects of ZnO-NPs and Cu-NPs to HGFs cell cultures were tested by MTT, LDH assays, production of ROS, and the activation of caspase-3. The results were analyzed using one-way ANOVA followed by Tukey tests, considering p < 0.05 as statistically significant.

RESULTS

For all strains, MICs of ZnO-NPs and Cu-NPs were in the range of 78.3 μg/mL-3906 μg/mL and 125 μg/mL-625 ug/mL, respectively. In a multispecies model, a significant decrease in the total biomass volume(μ3) was observed in response to exposure to 125 μg/mL of each NPs for which there was bactericidal activity. Significant differences were found between the volumes of viable and nonviable biomass exposed to nanostructures with Cu-NPs compared to ZnO-NPs. Both NPs induced mitochondrial dose-dependent cytotoxicity, ZnO-NPs increases LDH release and intracellular ROS generation. Cu-NPs at a concentration of 50 μg/mL induced production of cleaved caspase-3, activating the apoptotic pathway early and at low doses.

CONCLUSIONS

After 24 h, ZnO-NPs are biocompatible between 78-100 μg/mL and Cu-NPs below 50 μg/mL. Antibacterial activity in a monospecies model is strain dependent, and in a multispecies model was a lower doses after 10 min of exposure.

Effects of the Ionic and Nanoparticle Forms of Cu and Ag on These Metals' Bioaccumulation in the Eggs and Fry of Rainbow Trout (Oncorhynchus mykiss W.)

Nanotechnology is a rapidly growing field of science, and an increasing number of nanoproducts, including nanometals, can be found on the market. Various nanometals and the products that are manufactured based on them can help to fight bacteria and fungi, but they can also penetrate organisms and accumulate in them. This study aimed to compare the effects of two metals, silver (Ag) and copper (Cu), with known antibacterial and fungicidal properties in their ionic (AgNO₃, CuSO₄·5H₂O) and nanoparticle (AgNPs, CuNPs) forms on rainbow trout eggs and fry. Concentrations of metals ranging from 0 to 16 mg/L were used during egg swelling for 2 h. The swelling of eggs in Cu solutions resulted in an increase in Cu content in the eggs (just like in the case of Ag); however, the changes in fry were not significant in the case of both Ag and Cu. The concentrations of these metals in eggs was greatly affected by the applied form of Ag and Cu. Because CuNPs penetrated the embryo in fish eggs at lower concentrations compared to AgNPs, it would be worth considering them for antibacterial applications during egg incubation.

A unified in silico model based on perturbation theory for assessing the genotoxicity of metal oxide nanoparticles

Nanomaterials (NMs) are an ever-increasing field of interest, due to their wide range of applications in science and technology. However, despite providing solutions to many societal problems and challenges, NMs are associated with adverse effects with potential severe damages towards biological species and their ecosystems. Particularly, it has been confirmed that NMs may induce serious genotoxic effects on various biological targets. Given the difficulties of experimental assays for estimating the genotoxicity of many NMs on diverse biological targets, development of alternative methodologies is crucial to establish their level of safety. In silico modelling approaches, such as Quantitative Structure-Toxicity Relationships (QSTR), are now considered a promising solution for such purpose. In this work, a perturbation theory machine learning (PTML) based QSTR approach is proposed for predicting the genotoxicity of metal oxide NMs under various experimental assay conditions. The application of such perturbation approach to 6084 NM-NM pair cases, set up from 78 unique NMs, afforded a final PTML-QSTR model with an accuracy better than 96% for both training and test sets. This model was then used to predict the genotoxicity of some NMs not included in the modelling dataset. The results for this independent data set were in excellent agreement with the experimental ones. Overall, that thus suggests that the derived PTML-QSTR model is a reliable in silico tool to rapidly and cost-efficiently assess the genotoxicity of metal oxide NMs. Finally, and most importantly, the model provides important insights regarding the mechanism of the genotoxicity triggered by these NMs.

Comparative toxicity of nanoparticulate and ionic copper following dietary exposure to common carp (Cyprinus carpio)

Copper is an essential element for the normal growth and survival of all organisms including fish. However, its excessive presence in the environment can cause bioaccumulation and aquatic toxicology. The aim of the present study was to compare the dietary toxicity effects of two different Cu compounds, copper oxide nanoparticles (CuO-NPs) and ionic copper (CuSO₄) in juvenile common carp, Cyprinus carpio. To prepare experimental diets, two nominal concentrations of 100 and 1000 mg Cu kg^-1 diet were added to a basal diet. Carp (n = 450, average initial weight of 35.94 ± 5.35 g) were fed on the Cu-supplemented diets and basal diets for two 21-day courses as dietary exposure and recovery periods, respectively. The growth performance, survival rate and blood biochemical indices as well as copper accumulation in target organs of fish were investigated at the end of each exposure period. The results showed that the weight gain (WG) of carp significantly decreased coincident with increasing concentration of the both dietary Cu forms (P = 0.00). Both Cu sources at concentrations of 100 mg kg^-1 diet decreased the survival rate of fish (P = 0.003), likely due to more feed intake and thus increased copper toxicity. The both forms of dietary Cu at two different concentrations significantly decreased the plasma glutamate oxaloacetate transaminase (GOT) level compared to the control group (P = 0.008). Fish exposed to diets containing Cu sources except 100 mg Cu kg^-1 of CuO-NPs showed the lower glutamate pyruvate transaminase (GPT) activity in comparison to the control (P = 0.00). The plasma sodium level in1000 mg CuO-NPs kg^-1 diet was significantly lower than the control (P = 0.001). The plasma potassium level increased in the all Cu-supplemented groups except 100 mg kg^-1 of CuO-NPs after the dietary exposure period (P = 0.035). The copper accumulation was dose-dependent in all target organs. In 100 mg Cu kg^-1 dietary groups, the liver showed the highest Cu accumulation (P = 0.00), while in 1000 mg Cu kg^-1 dietary groups, the highest Cu content was observed in the intestine (P = 0.00). The results demonstrated the enhanced toxicological responses in fish after 21 days of dietary exposure, but the levels of most of biochemical indices and tissues Cu content decreased or returned to the control values after the recovery period.

Comparative Assessment of Genotoxic Impacts Induced by Zinc Bulk- and Nano-Particles in Nile tilapia, Oreochromis niloticus

Fish were separately exposed to 1/2 LC50/96 h values of bulk-Zn and nano-Zn for 7, 14, and 28 days. The induction of micronuclei (MN) and other eight nuclear abnormalities in erythrocytes showed marked time and size dependence. The frequencies of all nuclear anomalies were progressively elevated (p < 0.05) with increasing the time of exposure to both bulk-Zn and nano-Zn. Throughout the study periods, fish exposed to nano-Zn showed the maximum elevation in all studied nuclear anomalies. Based on the fragmented DNA values, both Zn forms induced tissue-specific DNA damage as following gills > liver > muscles. Moreover, nano-Zn exposed groups revealed a maximum percentage of DNA damage among all studied groups, especially after 14 days. The percentage of DNA damage was decreased in all tissues on the 28th day, which reflected the presence of an effective repair mechanism. Finally, nano-Zn exhibited more genotoxic effects than that of its bulk counterparts.

Transport and retention of copper oxide nanoparticles under unfavorable deposition conditions caused by repulsive van der Waals force in saturated porous media

Currently, copper oxide nanoparticles (CuO NPs) have been widely used in industry, manufacturing and agriculture. The transport and retention of CuO NPs are vital to understanding the fate as well as the life cycle of CuO NPs in the environment. This study systematically investigates the transport and retention of CuO NPs in saturated porous media, and the experimental results were explained by the CFT and DLVO theory. The van der Waals force between CuO NPs and collector was repulsive, resulting in the unfavorable deposition condition. Column experiments were conducted with saturated quartz sand under environmentally relevant pH (6, 8, 9), ionic strength (IS, 1, 10, 50 mM), and humic acid (HA, 0.1-10 mg-C/mL). Experimental results show that the breakthrough curves (BCTs) were affected by different pH and IS. Under pH 6 and 9, the mobility of CuO NPs was enhanced by high IS while the mobility was inhibited by high IS under pH 8. The mobility of CuO NPs was enhanced by humic acid and the effect was best at 0.5 mg-C/mL HA. The experimental results were successfully explained by CFT and DLVO theory, the main mechanisms were aggregation of CuO NPs, interaction energy and collision between CuO NPs and collector. In general, these findings can improve our understanding of the transport and retention of CuO NPs in subsurface environments, and suggest pH, IS, HA may be key factors governing mobility and stability of CuO NPs in natural environment.

Environmental exposure to non-essential trace elements in two bat species from urbanised (Tadarida teniotis) and open land (Miniopterus schreibersii) areas in Italy

Bats are particularly suited as bioindicators of trace element pollution due to their longevity and their position in the trophic chain. In this study, the concentrations of ten non-essential trace elements (Al, As, Ba, Cd, Hg, Pb, Sb, Sr, Th, Tl) were determined in the tissues (whole body, skin-fur, skinned body, liver, kidney and bone) of lactant Tadarida teniotis from a nursery colony in Rome. A large number of bats from this nursery died before fledging and had bone deformities and fractures. The concentrations of non-essential trace elements in bone and whole body were also analysed in adult specimens of Miniopterus schreibersii from a colony located in a natural park in Northern Italy. In lactant T. teniotis, the Pb concentration decreased in the following order: bone>liver>skinned body>whole body>skin-fur>kidney, and exceeded the toxic threshold associated with negative effects reported for different mammalian species. The levels of the other non-essential trace elements were within a range indicative of low environmental contamination in both species. Significant interspecies differences (P < 0.05) were observed for concentrations of Pb and Ba, higher in the bones of T. teniotis, and of Cd, Hg and Sr, higher in the bones of M. schreibersii. In lactant T. teniotis, the different sources of Pb exposure, through inhalation and/or food, may represent a potential threat to the colony of this synanthropic European bat.

Histopathological changes and antioxidant responses in common carp (Cyprinus carpio) exposed to copper nanoparticles

Despite the rapid increase of nanotechnology in a wide array of industrial sectors, the biosafety profile of nanomaterials remains undefined. The accelerated use of nanomaterials has increased the potential discharge of nanomaterials into the environment in different ways. The aquatic environment is mainly susceptible as it is likely to act as an ultimate sink for all contaminants. Therefore, this study assessed the toxicological impacts of waterborne engineered copper nanoparticles (Cu-NPs) on histology, lipid peroxidation (LPO), catalase (CAT), and glutathione (GSH) levels in the gills of common carp (Cyprinus carpio). Nanoparticles were characterized by XRD and SEM techniques. Before starting the sub-acute toxicity testing, 96 h LC50 of Cu-NPs for C. carpio was calculated as 4.44 mg/l. Then based on LC50, C. carpio of 40-45 g in weight were exposed to three sub-lethal doses of waterborne engineered Cu-NPs (0 or 0.5 or 1 or 1.5 mg/l) for a period of 14 days. The waterborne Cu-NPs have appeared to induce alterations in gill histology and oxidative stress parameters in a dose-dependent manner. The gill tissues showed degenerative secondary lamellae, necrotic lamella, fused lamella, necrosis of the primary and secondary lamella, edema, complete degeneration, epithelial lifting, degenerative epithelium, and hyperplasia in a dose-dependent manner. In the gill tissues, waterborne Cu-NPs caused a decreased level of CAT and elevated levels of LPO, and GSH in the fish exposed to the highest dose of 1.5 mg Cu-NPs/l of water. Our results indicate that the exposure to waterborne Cu-NPs was toxic to the aquatic organisms as shown by the oxidative stresses and histological alterations in C. carpio, a freshwater fish of good economic value.

Comparative tissue distribution and depuration characteristics of copper nanoparticles and soluble copper in rainbow trout (Oncorhynchus mykiss)

The continuously growing number of products containing nanoparticles (NPs) makes their presence in the environment inevitable, and given the well-known toxicity of dissolved metals, concerns regarding the toxicity of metal-based NPs have been raised. Whether metal-based NPs present similar or different toxicological effects compared with metal salts is an emerging field. In the present study, rainbow trout were intraperitoneally injected with CuSO₄ or copper NPs (CuNPs) to investigate tissue distribution and depuration characteristics. Fish injected with Cu showed an initial accumulation of Cu in the liver, kidney, gills, intestine, and carcass. The Cu concentration in the liver of CuNP-injected fish increased over time. It appears as though CuNPs accumulated in the liver at a greater rate than they were excreted. In livers of fish injected with CuSO₄ , the Cu concentration appeared to increase and reach an equilibrium, suggesting that copper was accumulated and excreted at the same rate. The possibility that CuNPs can accumulate at a higher rate than it is excreted in the liver warrants further investigation. The present study demonstrates the possibility of dietary uptake of CuNPs because elevated Cu concentrations were observed in carcass, gills, kidney, and intestine of fish gavaged with CuNPs. In conclusion, the results suggest that dietary CuNPs are taken up by the gut and preferentially accumulate in the liver. Environ Toxicol Chem 2019;38:80-89. © 2018 SETAC.

Comparative toxicity of silver nanoparticle and ionic silver in juvenile common carp (Cyprinus carpio): Accumulation, physiology and histopathology

Many studies have investigated the potential negative effects of silver on aquatic organisms, but most focused on short-term exposure in few species. Moreover, there are many uncertainties about differences in potential toxicity mechanisms and adverse effects of silver nanoparticles (AgNPs) and ionic form of silver (AgNO₃). We investigated chronic effects of AgNPs and AgNO₃ on the juvenile common carp (Cyprinus carpio). AgNPs and AgNO₃ accumulated in the liver, gill and intestine, respectively and highest was related to AgNPs. Our results indicated, silver uptake was accompanied with histological alteration in the target organs such that different tissue lesions were observed in exposed groups. Superoxide dismutase (SOD), catalase (CAT) and lactate dehydrogenase (LDH) activity and also hsp70, ghrelin and IGF-1 genes expression were induced in both forms. After 7 days, highest hsp70 gene expression was observed in AgNO₃ treatment and highest ghrelin and IGF-1 gene expression was observed in AgNPs treatment. The results revealed that adverse effects of AgNPs on different aspects of the health of juvenile common carp, may not be solely a result of particle dissolution. In addition, the main toxic mechanism of AgNPs was probably related to the accumulation of silver followed by the molecular and oxidative stress response.

Copper Nanoparticles Induced Genotoxicty, Oxidative Stress, and Changes in Superoxide Dismutase (SOD) Gene Expression in Cucumber (Cucumis sativus) Plants

With the increased use of metal nanoparticles (NPs), their access to the food chain has become a main concern to scientists and holds controversial social implications. This research particularly sheds light on copper nanoparticles (CuNP), as they have been commonly used in several industries nowadays. In this study, we investigated the phytotoxicity of CuNP on cucumber (Cucumis sativus) plants grown hydroponically. Atomic Absorption Spectroscopy (AAS), X-Ray Fluorescence (XRF), and Scanning Electron Microscopy (SEM) analysis confirmed that C. sativus treated with CuNP accumulated CuNP in the plant tissues, with higher levels in roots, with amounts that were concentration dependent. Furthermore, genotoxicity was assessed using Random amplified polymorphic DNA (RAPD) technique, and our results showed that CuNP caused genomic alterations in C. sativus. Phenotypical, physiological, and biochemical changes were assessed by determining the CuNP treated plant's total biomass, chlorophyll, H2O2 and MDA contents, and electrolyte leakage percentage. The results revealed notable adverse phenotypical changes along with decreased biomass and decreased levels of the photosynthetic pigments (Chlorophyll a and b) in a concentration-dependent manner. Moreover, CuNP induced damage to the root plasma membrane as determined by the increased electrolyte leakage. A significant increase in H2O2 and MDA contents were detected in C. sativus CuNP treated plants. Additionally, copper-zinc superoxide dismutase (Cu-Zn SOD) gene expression was induced under CuNP treatment. Overall, our results demonstrated that CuNP of 10-30 nm size were toxic to C. sativus plants. This finding will encourage the safe production and disposal NPs. Thus, reducing nano-metallic bioaccumulation into our food chain through crop plants; that possesses a threat to the ecological system.

Synthesis methods influence characteristics, behaviour and toxicity of bare CuO NPs compared to bulk CuO and ionic Cu after in vitro exposure of Ruditapes philippinarum hemocytes

Copper oxide (CuO) nanoparticles (NPs) are increasingly investigated, developed and produced for a wide range of industrial and consumer products. Notwithstanding their promising novel applications, concern has been raised that their increased use and disposal could consequently increase their release into marine systems and potentially affect species within. To date the understanding of factors and mechanisms of CuO (nano-) toxicity to marine invertebrates is still limited. Hence, we studied the characteristics and behaviour of two commercially available CuO NPs of similar size, but produced employing distinct synthesis methods, under various environmentally and experimentally relevant conditions. In addition, cell viability and DNA damage, as well as gene expression of detoxification, oxidative stress, inflammatory response, DNA damage repair and cell death mediator markers were studied in primary cultures of hemocytes from the marine clam Ruditapes philippinarum and, where applicable, compared to bulk CuO and ionic Cu (as CuSO₄) behaviour and effects. We found that the synthesis method can influence particle characteristics and behaviour, as well as the toxicity of CuO NPs to Ruditapes philippinarum hemocytes. Our results further indicate that under the tested conditions aggregating behaviour influences the toxicity of CuO NPs by influencing their rate of extra- and intracellular dissolution. In addition, gene expression analysis identified similar transcriptional de-regulation for all tested copper treatments for the here measured suite of genes. Finally, our work highlights various differences in the aggregation and dissolution kinetics of CuO particles under environmental (marine) and cell culture exposure conditions that need consideration when extrapolating in vitro findings.

Green synthesis of silver nanoparticles using Piper nigrum: tissue-specific bioaccumulation, histopathology, and oxidative stress responses in Indian major carp Labeo rohita

The aim of the present investigation is to assess the sublethal toxicity of biologically synthesized silver nanoparticles (Ag NPs) in Indian major carp Labeo rohita. Ag NPs used in the study were synthesized by using AgNO₃ with aqueous leaf extract of Piper nigrum. Median lethal concentration (LC₅₀) of synthesized Ag NPs was determined for 96 h (25 μg/L); 2.5 μg/L (1/10th LC₅₀) and 5 μg/L (1/5th LC₅₀) were taken as sublethal concentrations to evaluate the toxicity for 35 days. The results of the TEM, SEM, and EDX analyses revealed that Ag NPs were considerably accumulated in the gill, liver, and kidney of fish at both concentrations (2.5 and 5 μg/L). Consequently, the activity of the antioxidant enzymes, SOD and CAT, was significantly (P < 0.05) decreased in the gill, liver, and kidney when compared to the control group during the study period. However, lipid peroxidase (LPO) activity in the gill, liver, and kidney was significantly (P < 0.05) increased, and the result concluded a possible sign of free radical-induced oxidative stress in Ag NP-exposed fish than the sham-exposed individuals. The histopathological study also confirmed the alterations such as degeneration of lamella, lifting of lamellar epithelium, hepatic necrosis, pyknotic nuclei, increased intracellular space, and shrinkage of glomerulus elicited by Ag NPs in the gill, liver, and kidney of Labeo rohita with two different concentrations. The findings of the present study revealed that green synthesis of Ag NPs from Piper nigrum at sublethal concentrations leads to accumulation of Ag, oxidative stress, and histopathological alterations in the target organs of the fish, Labeo rohita.

Cellular and molecular responses of adult zebrafish after exposure to CuO nanoparticles or ionic copper

Due to their antimicrobial, electrical and magnetic properties, copper nanoparticles (NPs) are suitable for a vast array of applications. Copper can be toxic to biota, making it necessary to assess the potential hazard of copper nanomaterials. Zebrafish (Danio rerio) were exposed to 10 µg Cu/L of CuO NPs of ≈100 nm (CuO-poly) or ionic copper to compare the effects provoked after 3 and 21 days of exposure and at 6 months post-exposure (mpe). At 21 days, significant copper accumulation was only detected in fish exposed to ionic copper. Exposure to both copper forms caused histopathological alterations that could reduce gill functionality, more markedly in the case of ionic copper. Nevertheless, at 6 mpe higher prevalences of gill lesions were detected in fish previously exposed to CuO-poly NPs. No relevant histological alterations were detected in liver, but the lysosomal membrane stability test showed significantly impaired general health status after exposure to both metal forms that lasted up to 6 mpe. 69 transcripts appeared regulated after 3 days of exposure to CuO-poly NPs, suggesting that NPs could produce oxidative stress and reduce metabolism and transport processes. Thirty transcripts were regulated after 21 days of exposure to ionic copper, indicating possible DNA damage. Genes of the circadian clock were identified as the key genes involved in time-dependent differences between the two copper forms. In conclusion, each copper form showed a distinct pattern of liver transcriptome regulation, but both caused gill histopathological alterations and long lasting impaired health status in adult zebrafish.

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.

X-ray Spectroscopy Uncovering the Effects of Cu Based Nanoparticle Concentration and Structure on Phaseolus vulgaris Germination and Seedling Development

Nanoparticles properties such as solubility, tunable surface charges, and singular reactivity might be explored to improve the performance of fertilizers. Nevertheless, these unique properties may also bring risks to the environment since the fate of nanoparticles is poorly understood. This study investigated the impact of a range of CuO nanoparticles sizes and concentrations on the germination and seedling development of Phaseolus vulgaris L. Nanoparticles did not affect seed germination, but seedling weight gain was promoted by 100 mg Cu L^-1 and inhibited by 1 000 mg Cu L^-1 of 25 nm CuO and CuSO₄. Most of the Cu taken up remained in the seed coat with Cu hotspots in the hilum. X-ray absorption spectroscopy unraveled that most of the Cu remained in its pristine form. The higher surface reactivity of the 25 nm CuO nanoparticles might be responsible for its deleterious effects. The present study therefore highlights the importance of the nanoparticle structure for its physiological impacts.

Reactive oxygen species generation by copper(II) oxide nanoparticles determined by DNA damage assays and EPR spectroscopy

Copper(II) oxide nanoparticles (^NPCuO) have many industrial applications, but are highly cytotoxic because they generate reactive oxygen species (ROS). It is unknown whether the damaging ROS are generated primarily from copper leached from the nanoparticles, or whether the nanoparticle surface plays a significant role. To address this question, we separated nanoparticles from the supernatant containing dissolved copper, and measured their ability to damage plasmid DNA with addition of hydrogen peroxide, ascorbate, or both. While DNA damage from the supernatant (measured using an electrophoresis assay) can be explained solely by dissolved copper ions, damage by the nanoparticles in the presence of ascorbate is an order of magnitude higher than can be explained by dissolved copper and must, therefore, depend primarily upon the nanoparticle surface. DNA damage is time-dependent, with shorter incubation times resulting in higher EC₅₀ values. Hydroxyl radical (^•OH) is the main ROS generated by ^NPCuO/hydrogen peroxide as determined by EPR measurements; ^NPCuO/hydrogen peroxide/ascorbate conditions generate ascorbyl, hydroxyl, and superoxide radicals. Thus, ^NPCuO generate ROS through several mechanisms, likely including Fenton-like and Haber-Weiss reactions from the surface or dissolved copper ions. The same radical species were observed when ^NPCuO suspensions were replaced with the supernatant containing leached copper, washed ^NPCuO, or dissolved copper solutions. Overall, ^NPCuO generate significantly more ROS and DNA damage in the presence of ascorbate than can be explained simply from dissolved copper, and the ^NPCuO surface must play a large role.

Genotoxicity of metal based engineered nanoparticles in aquatic organisms: A review

Engineered nanoparticles (ENPs) are an emerging class of environmental contaminants, but are generally found in very low concentrations and are therefore likely to exert sub-lethal effects on aquatic organisms. In this review, we: (i) highlight key mechanisms of metal-based ENP-induced genotoxicity, (ii) identify key nanoparticle and environmental factors which influence the observed genotoxic effects, and (iii) highlight the challenges involved in interpreting reported data and provide recommendations on how these challenges might be addressed. We review the application of eight different genotoxicity assays, where the Comet Assay is generally preferred due to its capacity to detect low levels of DNA damage. Most ENPs have been shown to cause genotoxic responses; e.g., DNA or/and chromosomal fragmentation, or DNA strand breakage, but at unrealistic high concentrations. The genotoxicity of the ENPs was dependent on the inherent physico-chemical properties (e.g. size, coating, surface chemistry, e.tc.), and the presence of co-pollutants. To enhance the value of published genotoxicity data, the role of environmental processes; e.g., dissolution, aggregation and agglomeration, and adsorption of ENPs when released in aquatic systems, should be included, and assay protocols must be standardized. Such data could be used to model ENP genotoxicity processes in open environmental systems.

Ecotoxicological effects and mechanism of CuO nanoparticles to individual organisms

Copper oxide nanoparticles (CuO NPs) are used extensively in a variety of applications such as antimicrobial agent, photo-catalyst and gas sensors. The expanding production and widespread utilization of CuO NPs may pose risks to individual organisms and ecosystem. Comprehensive understanding the CuO NPs-induced adverse effects and their underlying mechanism are of great importance to assess the environmental risk of CuO NPs and to expand their use safely. However, toxic effects of CuO NPs to individual organisms and the mechanism of their action are still deficient and ambiguities. To ensure the safely use of CuO NPs, more attention should be paid on the long-term and chronic effects of CuO NPs at low concentration. Efforts should be devoted to develop techniques to differentiate toxicities induced by CuO NPs or dissolved Cu²⁺, and to reduce the toxicity of CuO NPs by controlling the particle diameter, modifying surface characteristic, selecting proper exposure route and regulating the release of Cu²⁺ from CuO NPs. This review provides a brief overview of toxicity of CuO NPs to individual organisms with a broad range of taxa (microorganisms, algae, plants, invertebrates and vertebrates) and to discuss the underlying toxicity mechanisms including oxidative stress, dynamic unbalance and coordination effects.

Effect of different metals on oxidative state and mitochondrial membrane potential in trout erythrocytes

Homeostasis of metal ions is critical for life and excessive exposure can promote cellular damage that could be due to oxidative damage. In this context we evaluated the effects of three different elements (copper, zinc and aluminum) on oxidative stress and mitochondrial functionality in nucleated trout erythrocytes (Oncorhynchus mykiss). Flowcytometric measurements using MitoProbe and DCFDA-H₂ as fluorescent probes, indicated that redox active copper was able to influence all the biological parameters considered while redox inert, zinc and aluminum, show no significant effects. Toxicity of Al and Zn represent a debated argument and their ability to interact with other endogenous metal ions/metal binding proteins could play a role modulating their cellular toxicity.

Methods of Synthesis, Properties and Biomedical Applications of CuO Nanoparticles

This study aims to provide an updated survey of the main synthesis methods of copper oxide (CuO) nanoparticles in order to obtain tailored nanosystems for various biomedical applications. The synthesis approach significantly impacts the properties of such nanoparticles and these properties in turn have a significant impact on their biomedical applications. Although not widely investigated as an efficient drug delivery system, CuO nanoparticles have great biological properties including effective antimicrobial action against a wide range of pathogens and also drug resistant bacteria. These properties have led to the development of various approaches with direct applications to the biomedical field, such as tailored surfaces with antimicrobial effect, wound dressings and modified textiles. It is also believed that these nanosystems could represent efficient alternatives in the development of smart systems utilized both for the detection of pathogens and for the treatment of infections.

Toxicity evaluation of copper oxide bulk and nanoparticles in Nile tilapia, Oreochromis niloticus, using hematological, bioaccumulation and histological biomarkers

The increased industrial applications of nanoparticles (NPs) augment the possibility of their deposition into aquatic ecosystems and threatening the aquatic life. So, this study aimed to provide a comparable toxicological effects of nano-CuO and bulk CuO on a common freshwater fish, Oreochromis niloticus. Fish were exposed to two selected doses (1/10 and 1/20 of the LC50/96 h) of both nano-/bulk CuO for 30 days. Based on the studied hematological parameters (RBCs count, hemoglobin content and hematocrit%), the two selected concentrations of CuO in their nano- and bulk sizes were found to induce significant decrease in all studied parameters. But, nano-CuO-treated fish showed the maximum decrease in all recorded parameters among the all studied groups especially at the low concentration of 1/20 LC50/96 h. Hematological status was also confirmed using the calculated blood indices (MCV, MHC and MCHC). In case of bulk CuO-treated groups, the significant decrease in the studied hematological parameters was not followed by any change in MCV and MCH (normocytic anemia), while fish that exposed to NPs showed a significant increase in all calculated blood parameters reflecting erythrocytes swelling which is related to the intracellular osmotic disorders (macrocytic anemia). Regarding metal bioaccumulation factor, the results showed that CuO NPs had more efficiency to internalize fish tissues (liver, kidneys, gills, skin and muscle). The accumulation pattern of Cu metal was ensured by histopathological investigation of liver, kidneys and gills. The histopathological analysis revealed various alterations that varied between adaptation responses and permanent tissue damage.

Where does the toxicity of metal oxide nanoparticles come from: The nanoparticles, the ions, or a combination of both?

The toxicity of metal oxide nanoparticles (NPs) has aroused great concern over the past few years. However, there still remains the question whether the toxicity of the metal oxide NPs originates from the released ions or the NPs themselves. In this study, the metal ion release of CuO, Fe2O3, ZnO, Co3O4, Cr2O3, and NiO NPs in aqueous media was investigated, and their contributions to the metal oxide NPs' inhibition on the bioluminescence of Photobacterium phosphoreum were studied. It was found that the ions release of the metal oxide NPs in aqueous media was complex, depending on both the dissolution and adsorption processes of the metal oxide NPs. The relationships between the metal oxide NPs' antibacterial effects and their released metal ions could be divided into three categories: (1) the ZnO NPs' antibacterial effect was due solely to the released Zn(2+); (2) the CuO NPs' antibacterial effect originated from both the released Cu(2+),and the CuO particles; and (3) the antibacterial effects of Fe2O3, Co3O4, Cr2O3, and NiO NPs were caused by the NPs themselves. Our findings suggest that the ions release and their contributions to the NPs' toxicity should be considered in the toxicity evaluations of the metal oxide NPs.

Genotoxic and cytotoxic effects of ZnO nanoparticles for Dunaliella tertiolecta and comparison with SiO2 and TiO2 effects at population growth inhibition levels

The increasing use of oxide nanoparticles (NPs) in commercial products has intensified the potential release into the aquatic environment where algae represent the basis of the trophic chain. NP effects upon algae population growth were indeed already reported in literature, but the concurrent effects at cellular and genomic levels are still largely unexplored. Our work investigates the genotoxic (by COMET assay) and cytotoxic effects (by qualitative ROS production and cell viability) of ZnO nanoparticles toward marine microalgae Dunaliella tertiolecta. A comparison at defined population growth inhibition levels (i.e. 50% Effect Concentration, EC50, and No Observed Effect Concentration, NOEC) with SiO2 and TiO2 genotoxic effects and previously investigated cytotoxic effects (Manzo et al., 2015) was performed in order to elucidate the possible diverse mechanisms leading to algae growth inhibition. After 72h exposure, ZnO particles act firstly at the level of cell division inhibition (EC50: 2mg Zn/L) while the genotoxic action is evident only starting from 5mg Zn/L. This outcome could be ascribable mainly to the release of toxic ions from the aggregate of ZnO particle in the proximity of cell membrane. In the main, at EC50 and NOEC values for ZnO NPs showed the lowest cytotoxic and genotoxic effect with respect to TiO2 and SiO2. Based on Mutagenic Index (MI) the rank of toxicity is actually: TiO2>SiO2>ZnO with TiO2 and SiO2 that showed similar MI values at both NOEC and EC50 concentrations. The results presented herein suggest that up to TiO2 NOEC (7.5mg/L), the algae DNA repair mechanism is efficient and the DNA damage does not result in an evident algae population growth inhibition. A similar trend for SiO2, although at lower effect level with respect to TiO2, is observable. The comparison among all the tested nanomaterial toxicity patterns highlighted that the algae population growth inhibition occurred through pathways specific for each NP also related to their different physicochemical behaviors in seawater.