Chronic dietary toxicity of zinc oxide nanoparticles in common carp (Cyprinus carpio L.): Tissue accumulation and physiological responses

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

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

Individual and combined impact of microplastics and lead acetate on the freshwater shrimp (Caridina fossarum): Biochemical effects and physiological responses

Microplastics and heavy metals pollution is recognised as a major problem affecting aquatic ecosystems. For this reason, this study aims to assess the toxicity of different concentrations of polyethylene microplastics (PE-MPs) (0.0, 500, and 1000 μg L-1) with a mean size of 15-25 μm and lead acetate Pb(C2H3O2)2 (0.0, 2.5, and 5 mg L-1), both individually and in combination, through the exposure of the freshwater grass shrimp, Caridinia fossarum for 15 days, focusing on microplastic interaction with co-occurring contaminants. After being exposed to both contaminants, either individually or in combination, significant alterations in numerous biochemical markers were observed. Specifically, exposure to lead acetate alone resulted in significant changes across ALP, AST, ALT, LDH, GGT, and BChE enzyme activity levels indicating hepatotoxicity and neurotoxicity. Also, Pb exposure led to alterations in total antioxidant capacity, MDA, total lipids, and glycogen contents, signalling the onset of oxidative stress. Exposure to PE-MPs alone led to changes in ALP, LDH, GGT, and BChE enzyme levels, and in MDA, total lipids, and glycogen samples' contents. Remarkably, the study observed increased bioaccumulation of lead acetate in samples treated with the combination, emphasizing the synergistic impact of PE-MPs on the toxicity of lead acetate. This synergy was also evident in AST and ALT enzyme activity levels and MDA contents. This underscores the necessity for measures to address both microplastic pollution and heavy metal contamination, taking into account the synergistic behaviour of MPs in the presence of concurrent contaminants.

Application of nZnO supported with nanoclay for improving shrimp immunity

This study discloses the nanoscale silicate platelet-supported nZnO (ZnONSP) applied as novel feed additives in aquaculture. The preparation of the nanohybrid (ZnO/NSP = 15/85, w/w) was characterized by UV-visible spectroscopy, powder X-ray diffraction and transmission electron microscope. The effects of ZnONSP on growth, zinc accumulation, stress response, immunity and resistance to Vibrio alginolyticus in white shrimp (Penaeus vannamei) were \demonstrated. To evaluate the safety of ZnONSP, shrimps (2.0 ± 0.3 g) were fed with ZnONSP containing diets (200, 400 and 800 mg/kg) for 56 days. Dietary ZnONSP did not affect the weight gain, specific growth rate, feed conversion ratio, survival rate, zinc accumulation, and the expression of heat shock protein 70 in tested shrimps. To examine the immunomodulatory effect of ZnONSP, shrimps (16.6 ± 2.4 g) were fed with the same experimental diets for 28 days. Dietary ZnONSP improved the immune responses of haemocyte in tested shrimps, including phagocytic rate, phagocytic index, respiratory burst, and phenoloxidase activity, and upregulated the expression of several genes, including lipopolysaccharide, β-1,3-glucan binding protein, peroxinectin, penaeidin 2/3/4, lysozyme, crustin, anti-lipopolysaccharide factor, superoxide dismutase, glutathione peroxidase, clotting protein and α-2-macroglobulin. In the challenge experiment, shrimps (17.2 ± 1.8 g) were fed with ZnONSP containing diets (400 and 800 mg/kg) for 7 days and then infected with Vibrio alginolyticus. Notably, white shrimps that received ZnONSP (800 mg/kg) showed significantly improved Vibrio resistance, with a survival rate of 71.4 % at the end of 7-day observation. In conclusion, this study discovers that ZnONSP is a new type of immunomodulatory supplement that are effective on enhancing innate cellular and humoral immunities, and disease resistance in white shrimp.

Ecotoxicological effects of zinc oxide nanoparticles (ZnO-NPs) on aquatic organisms: Current research and emerging trends

The rapid advancement of nanotechnology has contributed to the development of several products that are being released to the consumer market without careful analysis of their potential impact on the environment. Zinc oxide nanoparticles (ZnO-NPs) are used in several fields and are applied in consumer products, technological innovations, and biomedicine. In this sense, this study aims to compile existing knowledge regarding the effects of ZnO-NPs on non-target organisms, with the goal of ensuring the safety of human health and the environment. To achieve this objective, a systematic review of the available data on the toxicity of these nanomaterials to freshwater and marine/estuarine aquatic organisms was carried out. The findings indicate that freshwater invertebrates are the most commonly used organisms in ecotoxicological tests. The environmental sensitivity of the studied species was categorized as follows: invertebrates > bacteria > algae > vertebrates. Among the most sensitive species at each trophic level in freshwater and marine/estuarine environments are Daphnia magna and Paracentrotus lividus; Escherichia coli and Vibrio fischeri; Scenedesmus obliquus and Isochrysis galbana; and Danio rerio and Rutilus caspicus. The primary mechanisms responsible for the toxicity of ZnO-NPs involve the release of Zn2+ ions and the generation of reactive oxygen species (ROS). Thus, the biosynthesis of ZnO-NPs has been presented as a less toxic form of production, although it requires further investigation. Therefore, the synthesis of the information presented in this review can help to decide which organisms and which exposure concentrations are suitable for estimating the toxicity of nanomaterials in aquatic ecosystems. It is expected that this information will serve as a foundation for future research aimed at reducing the reliance on animals in ecotoxicological testing, aligning with the goal of promoting the sustainable advancement of nanotechnology.

Immunomodulation, Fish Health and Resistance to Staphylococcus aureus of Nile Tilapia (Oreochromis niloticus) Fed Diet Supplemented with Zinc Oxide Nanoparticles and Zinc Acetate

Recently some metal-based nanoparticles have gained serious attention from aquaculture and the fish feed industry as feed supplements. Oral supplementation of zinc oxide nanoparticles (ZnO-NPs) in fish feed, replacing Zn acetate (conventionally used zinc), is suggested as a cost-effective and efficient approach. Our study assessed the response of Nile tilapia, Oreochromis niloticus, fingerlings after its diet supplemented with chemically synthesized ZnO-NPs and zinc acetate under controlled conditions. ZnO-NPs were chemically synthesized and characterized. Tilapia fingerlings with an average body weight of 09.12 ± 1.23 g were randomly distributed into five groups. An 8-week trial was set with control and four experimental groups. Basal diet (D1) was used as control, whereas D2, D3 and D4 comprising 20, 40, and 60 mgkg-1 ZnO-NPs supplementation were experimental diets. Additionally, D5 was composed of a basal diet supplemented with 40 mgkg-1 of conventionally used zinc acetate. Significant improvement (P < 0.05) was found in nanoparticles and Zn acetate supplemented groups as compared to control, while the 40 mgkg-1 Zn-NPs supplemented diet (D3) showed best performance in terms of health parameters, oxidative status and disease resistance. Antioxidant profiling was based on catalase, superoxide dismutase, glutathione's transferase, and malondialdehyde; hematology included Hb, WBCs, RBCs, HCT MCV, MCH and MCHC; immunological parameters comprised IgM, lysozyme activity, phagocytic activity, respiratory burst activity, cholesterol, aspartate aminotransferase, alanine aminotransferase, glucose content, and total serum proteins. We report that the D3 (40 mgkg-1 ZnO-NPs supplementation) significantly (P < 0.05) improved health-related parameters as compared to the other groups. Moreover, D3 also showed significantly decreased mortality percentage when challenged by Staphylococcus aureus, while the Zn acetate supplemented diet group showed better results as compared to control. Overall results suggest the basal diet supplemented with 40 mgkg-1 ZnO-NP for enhanced health parameters, oxidative status, immune response, and disease resistance. Hence, 40mgkg-1 ZnO-NP can be recommended to formulate the practical diet of fish to boost health improvement, immunomodulation, and resistance to bacterial disease.

Multiple effects of ZnO nanoparticles on goldfish (Carassius auratus): Skin mucus, gut microbiota and stable isotope composition

The skin and the gut are direct target tissues for nanoparticles, yet attention to effects of metal-based nanoparticles (MNPs) on these two and the discrepancy in these effects remain inadequate. Here, effects of ZnO nanoparticles (nZnO) on skin mucus and gut microbiota of goldfish (Carassius auratus) were investigated, as well as further elements turnover and metabolic variations. After 14 days of exposure, considerable variations in levels of biomarkers (protein, glucose, lysozyme and immunoglobulin M) in skin mucus demonstrated significant stress responses to nZnO. nZnO exposure significantly reduced the abundance of Cetobacterium in the gut while increased that of multiple pathogens, and further leading to down-regulation of pathways such as carbohydrate metabolism, translation, and replication and repair. Decreased δ¹⁵N values indicated declined N turnover in vivo, further demonstrating the negative effect of nZnO on metabolism in the organism. Integration analysis of each biomarker using the biomarker response index version 2 (IBRv2) revealed concentration-dependent effects of nZnO on skin mucus, while effects on physiology in vivo was not, demonstrating the discrepancy in the toxicity pathways and toxic effects of nZnO on different tissues. This work improved our understanding about the comprehensive toxicity of nZnO on aquatic organism.

Combined toxic effects of environmental predominant microplastics and ZnO nanoparticles in freshwater snail Pomaceae paludosa

In the past few years, microplastics are one of the ubiquitous threatening pollutants in aquatic habitats. These persistent microplastics interact with other pollutants, especially nanoparticles were adherent on the surface, which causes potential hazards in the biota. In this study, the toxic effects of individual and combined (28 days) exposure with zinc oxide nanoparticles and polypropylene microplastics were assessed in freshwater snail Pomeacea paludosa. After the experiment, the toxic effect was evaluated by the estimation of vital biomarkers activities including antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), oxidative stress in carbonyl protein (CP), lipid peroxidation (LPO), and digestive enzymes (esterase and alkaline phosphatase). Chronic exposure to pollutants in snails causes increased reactive oxygen species level (ROS) and generates free radicals in their body which leads to impairment and alterations of biochemical markers. Where alteration in acetylcholine esterase (AChE) activity and decreased digestive enzymes (esterase and alkaline phosphatase) activities were observed in both individual and combined exposed groups. Further, histology results revealed the reduction of haemocyte cells, the disintegration of blood vessels, digestive cells, calcium cells, and DNA damage was also detected in the treated animals. Overall, when compared to individual exposures, combined exposure of pollutants (zinc oxide nanoparticles and polypropylene microplastics) causes more serious harms including decline and increased antioxidant enzyme parameters, damage the protein and lipids by oxidative stress, increased neurotransmitter activity, decrease digestive enzyme activities in the freshwater snail. The outcome of this study concluded that polypropylene microplastics along with nanoparticles cause severe ecological threats and physio-chemical effects on the freshwater ecosystem.

The interplay of calponin, wnt signaling, and cytoskeleton protein governs transgenerational phenotypic abnormalities in drosophila exposed to zinc oxide nanoparticles

ZnO nanoparticles (ZnO NPs) are widely used engineered nanomaterials. Due to induced genotoxicity, increased oxidative stress, and teratogenicity, these NPs have been reported to be toxic. In the present study, we emphasise the role of vital proteins in regulating ZnO NP-induced abnormal phenotypes, particularly the deformed thorax and single wing in the Drosophila melanogaster progeny fed on 0.1-10 mM ZnO NPs. To understand how protein expression regulates this particular phenotype on ZnO NPs exposure, toxicoproteomics profile of control and abnormal phenotype flies was generated using LC/MS/MS. Gene ontology enrichment studies of proteomics data were carried out using CLUEGO and STRAP software. The bioinformatics tool STRING was used to generate a protein-protein interaction map of key proteins of enrichment analysis. Following ZnO NP exposure, the differential expression of key proteins of the Wnt pathway was prominent. Altered expression of various proteins of the Wnt pathway (CaMKII), cytoskeleton (Actin), and calponin resulted in developmental defects in drosophila progeny. In addition, immunohistology studies showed a significant deviation in the expression of wingless protein of ZnO NPs treated larvae in comparison to control. According to these findings, the interaction of the wnt pathway and cytoskeletal proteins with ZnO NPs caused developmental abnormalities in the subsequent generation of drosophila, highlighting the transgenerational toxic effects of these nanoparticles.

Considerations for bioaccumulation studies in fish with nanomaterials

Nanomaterials (NMs) pose challenges in performing bioaccumulation studies in fish and in regulatory interpretation of results. Therefore, a clear guidance is needed to obtain reliable, reproducible and comparable results. By analysing all the available literature, we aim in this manuscript to identify the critical aspects that should be addressed in these type of studies. Seventy-eight studies from a total of 67 published articles were identified in which a variety of approaches were used: aqueous exposure (49 studies), dietary exposure (19), and pre-exposed animals for trophic transfer studies (10). The NMs tested included TiO₂, Zn, ZnO, Cu, CuO, Ag, Au, CeO₂, Fe₂O₃, Fe₃O₄, Se, CdS, CdSe/ZnS-QDs, CdTe/ZnS-QDs, graphene, fullerenol and MWCNTs. In general, there is a scarcity of bioaccumulation studies for the different NMs. In particular, studies that use the dietary exposure route are lacking. TiO₂ NMs are the most studied for bioaccumulation potential in fish (20%), whereas very few data were available for CuO, FeO and carbon-based NMs. Different information gaps were identified in these studies that hamper overall conclusions to be made on the bioaccumulation potential of NMs. The main critical issues related to NM testing for bioaccumulation include: maintenance of stable exposure concentrations, the influence of feeding regimen on uptake and elimination, the use of appropriate feed spiking methodologies, the potential need for testing different concentrations, and the reporting of bioaccumulation endpoints (BCF/BMF). Each of these issues needs further guidance to allow proper use and reporting of NM bioaccumulation data for regulatory purposes.

Protective effects of Allium hirtifolium extract against foodborne toxicity of Zinc oxide nanoparticles in Common carp (Cyprinus carpio)

The use of nano-sized materials is increasingly growing, while consequent health and environmental risks are still disputed. On the other hand, plant extracts have been reported to improve fish general health status and enhance antioxidant capacity. Thus, the present study was aimed to assess potential effects of Allium hirtifolium extract (AHE) to fortify antioxidant responses of Common carp (Cyprinus carpio) exposed to foodborne Zinc oxide nanoparticles (ZnO-NPs). Five hundred and forty fish were randomly allocated into 18 tanks and received six diets including a basal diet (as control), basal diet incorporated with either 13 mg/kg (ZnO-25) or 26 mg/kg (ZnO-50) of ZnO-NPs, 1.5% AHE (AHE-1.5), and similar concentrations of ZnO-NPs plus AHE (ZnO-25-AHE) and (ZnO-50-AHE) for a period of 30 days. Results revealed that blood indices, stress biomarkers (glucose and cortisol), and antioxidant parameters and genes in AHE-1.5 group were significantly modulated and improved when compared to other groups (P < 0.05). In AHE-enriched groups, serum and liver tissue antioxidative parameters were enhanced as reflected in a noticeable decrease in malondialdehyde value and an increase in catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase. However, current results showed that diets incorporated with ZnO-NPs elevated the stress parameters besides a significant reduction for most measured biochemical parameters and AHE supplementation ameliorated these effects in terms of improving antioxidant parameters. In ZnO-25-AHE, and ZnO-50-AHE, the values for expression of GPx were found significantly (P < 0.05) different from that of ZnO-25 and ZnO-50. On the contrary, SOD showed a non-significant difference (P > 0.05) among control, ZnO-25, and ZnO-50-AHE, also in-between ZnO-25 and ZnO-25-AHE. The present results indicate that AHE supplementation could trigger antioxidant responses both at tissue and molecular levels suggesting its outstanding protective effects against foodborne toxicity of ZnO-NPs in Common carp.

Recent advances on botanical biosynthesis of nanoparticles for catalytic, water treatment and agricultural applications: A review

Green synthesis of nanoparticles using plant extracts minimizes the usage of toxic chemicals or energy. Here, we concentrate on the green synthesis of nanoparticles using natural compounds from plant extracts and their applications in catalysis, water treatment and agriculture. Polyphenols, flavonoid, rutin, quercetin, myricetin, kaempferol, coumarin, and gallic acid in the plant extracts engage in the reduction and stabilization of green nanoparticles. Ten types of nanoparticles involving Ag, Au, Cu, Pt, CuO, ZnO, MgO, TiO₂, Fe₃O₄, and ZrO₂ with emphasis on their formation mechanism are illuminated. We find that green nanoparticles serve as excellent, and recyclable catalysts for reduction of nitrophenols and synthesis of organic compounds with high yields of 83-100% and at least 5 recycles. Many emerging pollutants such as synthetic dyes, antibiotics, heavy metal and oils are effectively mitigated (90-100%) using green nanoparticles. In agriculture, green nanoparticles efficiently immobilize toxic compounds in soil. They are also sufficient nanopesticides to kill harmful larvae, and nanoinsecticides against dangerous vectors of pathogens. As potential nanofertilizers and nanoagrochemicals, green nanoparticles will open a revolution in green agriculture for sustainable development.

Attractive study of the antimicrobial, antiviral, and cytotoxic activity of novel synthesized silver chromite nanocomposites

Antibiotic resistance is a global problem. This is the reason why scientists search for alternative treatments. In this regard, seven novel silver chromite nanocomposites were synthesized and assayed to evaluate their antimicrobial, antiviral, and cytotoxic activity. Five bacterial species were used in this study: three Gram-positive (Bacillus subtilis, Micrococcus luteus, and Staphylococcus aureus) and two Gram-negative (Escherichia coli and Salmonella enterica). Three fungal species were also tested: Candida albicans, Aspergillus niger, and A. flavus. The MIC of the tested compounds was determined using the bifold serial dilution method. The tested compounds showed good antibacterial activity. Maximum antibacterial activity was attained in the case of 15 N [Cobalt Ferrite (0.3 CoFe₂O₄) + Silver chromite (0.7 Ag_0.5Cr_2.5O₄)] against M. luteus. Concerning antifungal activity, C. albicans was the most susceptible fungal species. The maximum inhibition was recorded also in case of 15 N [Cobalt Ferrite (0.3 CoFe₂O₄) + Silver chromite (0.7 Ag_0.5Cr_2.5O₄)]. The most promising antimicrobial compound 15 N [Cobalt Ferrite (0.3 CoFe₂O₄) + Silver chromite (0.7 Ag_0.5Cr_2.5O₄)] was assayed for its antiviral and cytotoxic activity. The tested compound showed weak antiviral activity. The cytotoxic activity against Mammalian cells from African Green Monkey Kidney (Vero) cells was detected. The inhibitory effect against Hepatocellular carcinoma cells was detected using a MTT assay. The antimicrobial effect of the tested compounds depends on the tested microbial species. The tested compounds could be attractive and alternative antibacterial compounds that open a new path in chemotherapy.

Co-exposure of zinc oxide nanoparticles and multi-layer graphenes in blackfish (Capoeta fusca): evaluation of lethal, behavioural, and histopathological effects

Zinc oxide nanoparticles (ZnO NPs) and multi-layer graphenes (MLGs) are widely used, and due to the lack of appropriate wastewater treatment may end up in the aquatic environment, with unknown consequences to biota. The main purpose of this study was to assess the acute toxicity, histopathological and behavioural changes caused by the exposure of ZnO NPs and MLGs, alone and combined, to the blackfish Capoeta fusca. The estimated mean 96 h-LC₅₀ for ZnO NPs was 4.9 mg L^-1 and 68.4 mg L^-1 for MLGs. In combination, MLGs increased the acute toxicity of the ZnO NPs. The effects of the different NPs on the gills included hyperplasia, aneurisms, and fusion of the lamellae. In the intestine, exposure to the NPs resulted in an increase in the number and swelling of goblet cells and tissue degeneration. Loss of balance, restlessness, erratic and abnormal swimming patterns were the most common behavioural changes seen in the ZnO NPs' exposed blackfish. In contrast with the acute toxicity findings, MLGs decreased the histopathological and behavioural effects of the ZnO NPs on both gills and intestinal tissues as well as fish behaviour. Our experimental results illustrated insights into the simultaneous exposure assessment of metal-based NPs and carbon nanomaterials, although further research is needed on the interactions exposure of these substances to interpreting the toxicological effects of metal-based nanomaterials seen in exposed organisms.

Toxicological effects of three different types of highly pure graphene oxide in the midge Chironomus riparius

Graphene oxide (GO) is a carbon nanomaterial used in electronics, biomedicine, environmental remediation and biotechnology. The production of graphene will increase in the upcoming years. The carbon nanoparticles (NPs) are released into the environment and accumulated in aquatic ecosystems. Information on the effects of GO in aquatic environments and its impact on organisms is still lacking. The aim of this study was to synthesise and characterise label-free GO with controlled lateral dimensions and thickness - small GO (sGO), large GO (lGO) and monolayer GO (mlGO) - and determine their impact on Chironomus riparius, a sentinel species in the freshwater ecosystem. Superoxide dismutase (SOD) and lipid peroxidation (LPO) was evaluated after exposures for 24 h and 96 h to 50, 500, and 3000 μg/L. GOs accumulated in the gut of C. riparius and disturbed its antioxidant metabolism. We suggest that all types of GO exposure can upregulate of SOD. Moreover, both lGO and mlGO treatments caused LPO damage in C. riparius in comparison to sGO, proving its favourable lateral size impact in this organism. Our results indicate that GOs could accumulate and induce significant oxidative stress on C. riparius. This work shows new information about the potential oxidative stress of these NMs in aquatic organisms.

Mitochondria-Dependent Oxidative Stress Mediates ZnO Nanoparticle (ZnO NP)-Induced Mitophagy and Lipotoxicity in Freshwater Teleost Fish

Due to many special characteristics, zinc oxide nanoparticles (ZnO NPs) are widely used all over the world, leading to their wide distribution in the environment. However, the toxicities and mechanisms of environmental ZnO NP-induced changes of physiological processes and metabolism remain largely unknown. Here, we found that addition of dietary ZnO NPs disturbed hepatic Zn metabolism, increased hepatic Zn and lipid accumulation, downregulated lipolysis, induced oxidative stress, and activated mitophagy; N,N,N',N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN, Zn²⁺ ions chelator) alleviated high ZnO NP-induced Zn and lipid accumulation, oxidative stress, and mitophagy. Mechanistically, the suppression of mitochondrial oxidative stress attenuated ZnO NP-activated mitophagy and ZnO NP-induced lipotoxicity. Taken together, our study elucidated that mitochondrial oxidative stress mediated ZnO NP-induced mitophagy and lipotoxicity; ZnO NPs could be dissociated to free Zn²⁺ ions, which partially contributed to ZnO NP-induced changes in oxidative stress, mitophagy, and lipid metabolism. Our study provides novel insights into the impacts and mechanism of ZnO NPs as harmful substances inducing lipotoxicity of aquatic organisms, and accordingly, metabolism-relevant parameters will be useful for the risk assessment of nanoparticle materials in the environment.

Evaluation of Nephrotoxicity in Oreochromis niloticus After Exposure to Aluminum Oxide Nanoparticles: Exposure and Recovery Study

Nephrotoxic impacts of Al₂O₃ nanoparticles (NPs) were studied in Oreochromis niloticus after seven days of exposure and fifteen days of recovery periods. Fish were classified as group I (dechlorinated water); group II (2 mg/L Al₂O₃NPs); group III (4 mg/L Al₂O₃NPs); group IV (8 mg/L Al₂O₃NPs). Blood creatinine and uric acid levels showed marked increases in groups III and IV. A dose-dependent disturbance in renal antioxidant components was recorded as indicated by elevated catalase, superoxide dismutase, thiobarbituric acid reactive substances levels, and decreased glutathione reduced concentration. Renal histopathology was recorded with the highest % of appearance in group IV. A reduction in renal Al content, kidney function biomarkers (excepting group IV), and enhanced antioxidant status were observed after applying a recovery strategy. Several structural damages were identified following the recovery period, but the alteration frequencies indicated regressive histopathological changes. The Al₂O₃NPs-induced nephrotoxicity can be reduced after applying a suitable recovery period.

Toxicological effects of the chemical and green ZnO NPs on Cyprinus carpio L. observed under light and scanning electron microscopy

Nanoparticles in aquatic bodies cause serious harm to the aquatic organisms when accumulated in high amounts. However, green nanoparticles synthesized using plants can be less toxic as compared to chemical nanoparticles. Hence, we designed our study to investigate the toxicological effects of chemical and green zinc oxide nanoparticles (ZnO NPs) on the biological activity of juvenile Cyprinus carpio. The green ZnO NPs were synthesized from Solieria robusta, and chemical ZnO NPs were synthesized using zinc chloride solution and ammonium hydroxide. Characterization was done by using light microscopy, scanning electron microscope (SEM), Fourier transmission infrared radiation, and X-ray diffraction (XRD) techniques. The highest absorbance of nanoparticles was observed at 360 which confirmed the synthesis of ZnO. The SEM analysis showed that green nanoparticles were hexagonal while the chemical nanoparticles were spherical to cubic in shape. Definite peaks were observed in XRD of green and chemical NPs at 2θ angles 45.84° and 32.18°, respectively. Oxidative stress was determined by chemical analysis of catalase, glutathione S-transferase (GST), glutathione (GSH), and lipid peroxidation (LPO) activities. The toxicological effects of chemical ZnO NPs on the catalase, LPO, GST, and GSH activities were more than green ZnO NPs. The histopathological investigation proved that the effect of chemical nanoparticles was worse than green ZnO NPs. More tissue damage was found in chemical nanoparticles than green synthesized nanoparticles. It was concluded that chemical nanoparticles can be replaced by green nanoparticles, as green nanoparticles are eco-friendly with less toxicological effects. This replacement can limit the toxic effect of nanoparticles when they get accumulated in high amounts in water bodies.

A review of the effects of metallic nanoparticles on fish

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

Dietary silymarin, Silybum marianum extract ameliorates cadmium chloride toxicity in common carp, Cyprinus carpio

The present study evaluated the protective effects of silymarin extract (SIE) on cadmium chloride toxicity in common carp, Cyprinus carpio. Four experimental group were considered for the experiment including: SIE0 (control): non-SIE-supplemented fish, SIE1: fish supplemented with 400 mg SIE/kg diet, SIE2: fish supplemented with1400mg SIE/kg diet, SIE3: fish supplemented with 2400 mg SIE/kg diet). Fish were fed experimental diet for 60 days and then exposed to cadmium chloride (1.5 mg/l or 25% of LC50–96 h) and antioxidant defense components and the survival rate assayed. After 60 days feeding trial, total antioxidant capacity (TAC) levels significantly increased (P<0.01) in 1400–2400 mg SIE/kg diet treatments compared to those in control and 400 mg SIE/kg diet treatment. Malondialdehyde (MDA) (P>0.01) and acetylcholinesterase (AChE) levels (P>0.01) remained unchanged during the feeding period in all treatments. Hepatic catalase (CAT) in all SIE supplemented groups and superoxide dismutase (SOD) and glutathione peroxidase (GPx) in 1400–2400 mg SIE/kg diet treatments significantly elevated (P<0.01) in response to SIE. Plasma levels of hepatic metabolic enzymes [alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), creatine kinase (CK), lactate dehydrogenase (LDH) ] remained unchanged (P>0.01) in all experimental groups over feeding period. After exposure to cadmium chloride, TAC levels were significantly elevated (P<0.01) in all experimental groups. In control and 400 mg SIE/kg diet treatment, TAC showed lower levels (P<0.01) compared to other groups. MDA levels were significantly increased (P<0.01) in control and fish supplemented with 400 and 1400 mg SIE/kg diet. TAC in the fish of 2400 mg SIE/kg diet treatment remained unchanged (P>0.01), following the exposure. CAT (P<0.01), SOD (P<0.01) and GPx (P<0.01) were significantly elevated in response to cadmium chloride in all groups. However, the treatments, 1400 and 2400 mg SIE/kg diet, showed lower increases (P<0.01) of enzymes. AChE activity (P<0.01) in the liver were significantly decreased in control and fish fed 400 and 1400 mg SIE/kg diet. Exposure to cadmium significantly increased (P<0.01) the plasma levels of ALT, AST, ALP and LDH in control and those fed 400 and 1400 mg SIE/kg diet. The findings of the current study indicated that SIE at a rate of 1400–2400mg/kg diet might enhance antioxidant defense and protect hepatocytes against toxic effects of cadmium.

The protective role of vitamins (E + C) on Nile tilapia (Oreochromis niloticus) exposed to ZnO NPs and Zn ions: Bioaccumulation and proximate chemical composition

The accumulation potency of zinc nanoparticles in Nile tilapia (Oreochromis niloticus) were previously studied but their impacts on proximate chemical composition in muscle tissue by describing the dose-dependent accumulation and the protective role of vitamins (E + C), have not been investigated. Therefore, this study was carried out to assess the protective role of vitamins (E + C) on Zn accumulation in muscle and gill tissues of O. niloticus exposed to three sublethal concentrations (1/8 LC50, 1/4 LC50, and 1/2 LC50) of zinc oxide nanoparticles (ZnO NPs) compared to zinc oxide bulk particles (ZnO BPs) as well as their effects on the induced chemical composition alterations for different experimental periods (7, 14, 21, and 28 day). The data displayed that fish exposed to the different sublethal concentrations of ZnO NPs or ZnO BPs have a significant increase (p<0.05) in Zn ions accumulation in muscle and gill tissues compared to control group but Zn was accumulated in gill tissue higher than muscle tissue at all exposure periods. Also, Zn accumulation was higher in fish tissues exposed to ZnO NPs than ZnO BPs. On the other hand, groups supplemented with vitamins (E + C) showed a significant decreasing (p<0.05) in accumulated Zn levels compared to groups without supplementation. The values of these supplemented groups returned to similar levels established in the control at low concentrations but still higher than control at the high concentrations. Furthermore, the results showed that moisture and ash content slightly increased while protein and fat decreased in fish exposed to ZnO NPs or ZnO BPs compared to control group. In conclusion, the findings supported that a combination of vitamins (E + C) reduced Zn accumulation and ameliorated chemical composition alterations in O.niloticus fish.

Trophic transfer potential of nTiO2, nZnO, and triclosan in an algae-algae eating fish food chain

Little is known about the trophic transfer of nanoparticles and personal care products via dietary exposure in an algae-algae eating fish food chain. The bioaccumulation of nano-TiO₂ (P25 - nTiO₂), nano-ZnO (nZnO), and triclosan (TCS) in eight different combinations were explored in this study through algae, Asterococcus superbus, to fish, Gyrinocheilus aymonieri. Results found the bioaccumulation of TCS changed with algal biomass, while the bioaccumulation of Ti and Zn varied with the amount of lipids and proteins in algal cells. In algae, Ti was in the form of nTiO₂ and Zn in the form of zinc ion. Due to dietary exposure, Ti and Zn quantity in fish was closely related to that in algae. The quantity of Ti and Zn in algae and fish exposed to the interaction of nTiO₂ * nZnO* TCS was higher than that in other treatments. The uptake of Ti and Zn in algae exposed to the interaction of nTiO₂ * nZnO had been inhibited, and the corresponding fish also had less Ti and Zn in their tissues. nTiO₂-containing treatments had higher Ti proportion in muscle than gill in fish. Treatment nZnO had the most Zn in gill, whereas nZnO * TCS-containing treatments had higher Zn proportion in gut than other tissues. No observation of TCS in fish in all treatments suggested the removal and metabolism of TCS might be induced by tissue recovery and acclimation. This is the first report on trophic transfer of mixed nanoparticles and personal care product in an algae-algae eating fish two-stage food chain.

In vivo assessments for predicting the bioavailability of nanoencapsulated food bioactives and the safety of nanomaterials

Use of nano-sized materials to design novel delivery systems is actually a double-edged sword regarding the enhancement of absorption and bioavailability of encapsulated bioactives as well as the unpredictable phenomena inside the living cells causing health concerns. So, comprehensive investigations on the use of nanomaterials in foods and their biological fate are needed. To reach this goal, both in vitro and in vivo techniques have been extensively applied. Besides the in vitro models such as cell culture and yeast/bacteria, different live animal models like mice, rat, Drosophila melanogaster, Caenorhabditis elegans, Zebrafish and dog can be applied to study bioavailability and safety of nanodelivery systems. However, considering the low correlation between the achieved results of in vitro and in vivo assays, in vivo tests are the first priority due to providing a real physiological condition. On the other hand, uncorrelated results by in vivo assays represent a serious problem to compare them. To defeat the issues in setting an in vivo research for the nanodelivery systems, all restrictions and FDA regulations is likely to be considered to improve the assays authenticity. This review takes a comprehensive look at the different types of in vivo assays and model organisms that has been utilized for the investigation of bioavailability, release profile and possible toxicity of food-based nanomaterials so far.

Toxicity of gold nanorods on Ceriodaphnia dubia and Danio rerio after sub-lethal exposure and recovery

Gold nanorods (AuNRs) are rod-shaped nanoparticles (NPs) with special optical properties that allow their application in several areas including photothermal therapy, diagnosis, drug and gene delivery, cellular imaging, and biosensors. Their high potential for many applications increases the possibility of release in aquatic environments, which can cause risks to organisms. In this study, we evaluated toxic effects of AuNRs on cladoceran and fish (Ceriodaphnia dubia and Danio rerio) and their recovery after post-exposure periods. The EC₅₀ of 0.03 mg L^-1 was found for C. dubia in the acute exposure. There was a significant decrease in the number of neonates produced and in the filtration rate of C. dubia after sub-lethal exposure to AuNRs. The toxic mechanism of these NPs to cladocerans was attributed to increases in the reactive oxygen species (ROS) generation. After 4 h of recovery in clean medium, C. dubia were able to reestablish the filtration rate. Enzymatic biomarkers for D. rerio showed significant increases in the activity of superoxide dismutase, catalase, and lipid peroxidation after sub-lethal exposure to AuNRs. These biomarkers were recovered after 168 h in clean water. These results are pivotal on the comprehension of AuNR toxicity to aquatic organisms and are useful in assessing this novel nanomaterial impacts on aquatic biota.

Bioaccumulation and toxicokinetics of zinc oxide nanoparticles (ZnO NPs) co-exposed with graphene nanosheets (GNs) in the blackfish (Capoeta fusca)

In this study, we investigated the bioaccumulation and toxicokinetics of zinc oxide nanoparticles (ZnO NPs) alone and in the presence of graphene nanosheets (GNs) in the blackfish (Capoeta fusca). Blackfish were exposed via water to two ZnO NPs concentrations alone or as a combination with GNs and uptake of Zn into the gills, intestine, liver, and kidney was assessed at 7, 14 and 28 d. Zn elimination from these tissues was then assessed after a further 7, 14 and 28 d in clean water for both ZnO NPs concentrations and combined ZnO NPs/GN exposures. In the body tissues analyzed of exposed fish, the highest amounts of Zn occurred in the intestine and the lowest amount in the liver. Zn levels in blackfish after 28 d of exposure were higher in all treatment groups compared to those on 7 d (p < 0.05). For both ZnO NPs exposure concentrations, the highest amount of Zn was eliminated from the intestine, followed by the gills. Furthermore, elimination kinetics for both ZnO NPs concentrations alone and in combination with GNs showed that the shortest half-life for Zn is occurring in the intestine. Moreover, uptake rates of Zn in fish exposed to ZnO NPs + GNs followed the same pattern observed for the ZnO NP, with intestine and gills having the highest levels followed by kidney and liver. Thus, we show accumulation and elimination of Zn from ZnO NPs in blackfish depends on the tissue, exposure concentration and duration, and is dependent on the presence of GNs.

Ameliorative effect of vitamins (E and C) on biochemical alterations induced by sublethal concentrations of zinc oxide bulk and nanoparticles in Oreochromis niloticus

The comparison between bulk and nano ZnO particles were antecedently studied but describing the dose-dependent toxicity and the ameliorative effect of vitamins (E and C) in Oreochromis niloticus, have not been previously documented. Therefore, the present study was designed to investigate the ameliorative effect of vitamins (E and C) against oxidative stress and biochemical alterations induced by sublethal concentrations of zinc oxide bulk particles (ZnOBPs) and zinc oxide nanoparticles (ZnONPs). Toxicity tests were carried out on O. niloticus and showed that 96 h LC₅₀ values of ZnOBPs and ZnONPs were 84 mg/l and 5.6 mg/l respectively. Exposure of the studied fish to these sublethel concentrations for 7, 14, 21 & 28 days showed a significant increase (p < 0.05) in serum glucose, AST, ALT, creatinine, urea and uric acid compared to control groups while, fish groups exposed to ZnOBPs or ZnONPs and supplemented with vitamins E and C, their serum enzyme concentrations were decreased compared to the groups without supplementation after 7, 14, 21 and 28 day. On the other hand, antioxidant defense enzymes (SOD, CAT and GST) activity in O.niloticus fish were increased significantly (p < 0.05) when exposed to sublethal concentrations of ZnOBPs or ZnONPs compared to the control value. However, fish groups supplemented with vitamins (E and C) have a decrease in SOD, CAT and GST enzymes activity when compared to unsupplemented groups and the values returned to similar levels established in the control at low concentrations but still higher than control at the high concentrations.

Chemically and Green Synthesized ZnO Nanoparticles Alter Key Immunological Molecules in Common Carp (Cyprinus carpio) Skin Mucus

This study was conducted to compare the effects of commercially available (C) and green synthesized (GS) Zinc oxide nanoparticles (ZnO-NPs) on immunological responses of common carp (Cyprinus carpio) skin mucus. GS ZnO-NPs were generated using Thymus pubescent and characterized by UV–vis diffuse reflectance spectroscopy (DRS), Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX). Fish (n = 150) were randomly allocated into five groups in triplicate and received a waterborne concentration of 0% (control), 25%, and 50% of LC50 96 h of commercially available (C1 and C2) and green synthesized ZnO-NPs (GS1 and GS2) for 21 days. Results from XRD displayed ZnO-NPs with 58 nm in size and UV-vis DRS, EDX, and FT-IR analysis showed that some functional groups from plant extract bonded to the surface of NPs. The SEM images showed that ZnO-NPs have conical morphology. Acute toxicity study showed a higher dose of LC50_96h for green synthesized ZnO-NPs (78.9 mg.L⁻¹) compared to the commercial source (59.95 mg.L⁻¹). The highest activity of lysozyme and alternative complement activity (ACH50) were found in control and GS1 groups. A significant decrease in alkaline phosphatase activity (ALP) was found in C1 and C2 groups compared to other treatments. Protease activity (P) was significantly decreased in the C2 group compared to the control and GS groups. Total immunoglobulin (total Ig) content was the highest in the control. In addition, total Ig in the GS1 group was higher than GS2. The exposure to ZnO-NPs lowered total protein content in all experimental groups when compared to control. Present findings revealed lower induced immunosuppressive effects by green synthesized ZnO-NPs on key parameters of fish skin mucus.

Hazardous Effects of SiO2 Nanoparticles on Liver and Kidney Functions, Histopathology Characteristics, and Transcriptomic Responses in Nile Tilapia (Oreochromis niloticus) Juveniles

Simple Summary

Waterborne exposure of Nile tilapia (Oreochromis niloticus) juveniles to sub-lethal concentrations of silicon dioxide nanoparticles (SiO₂NPs) induced hepato-renal damage through elevation of aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase (ALP) activities as well as creatinine and blood urea levels. SiO₂NPs induced irreversible dose-dependent histopathological changes in the hepatopancreas, gills, and posterior kidneys, alongside modulation of the pro-inflammatory cytokines, apoptosis-related genes, and oxidative stress genes in gills and liver of exposed fish.

Abstract

The current investigation assessed the impacts of sub-lethal concentrations of silicon dioxide nanoparticles (SiO₂NPs) on hepato-renal functions, histopathological characteristics, and gene transcription in gills and liver of Nile tilapia juveniles. Fish were exposed to 20, 40, and 100 mg/L of SiO₂NPs for 3 weeks. Pairwise comparisons with the control group showed a significant dose-dependent elevation in serum ALP, ALT, and AST enzyme activities as well as blood urea and creatinine levels in SiO₂NP-intoxicated groups. Exposure to 100 mg/L SiO₂NPs significantly upregulated expression of HSP70, TNF-α, IL-1β, and IL-8 genes in the gills as compared to the control group. Moreover, exposure to 100 mg/L SiO₂NPs significantly upregulated the expression SOD, HSP70, IL-1β, IL-8, and TNF-α genes in the hepatic tissues as compared to the control group. Exposure of fish to 20 mg SiO₂NPs/L significantly increased the mRNA expression levels of IL-12 in both the gills and liver tissues. Notably, all tested SiO₂NP concentrations significantly upregulated the transcription of CASP3 gene in gills and liver of Nile tilapia as compared to the control group. Interestingly, varying histopathological alterations in renal, hepatopancreatic, and branchial tissues were observed to be correlated to the tested SiO₂NP concentrations. In conclusion, our results provide additional information on the toxic impacts of SiO₂NPs in Nile tilapia at the hematological, tissue, and molecular levels.

Effects of polystyrene nanoplastics on Ctenopharyngodon idella (grass carp) after individual and combined exposure with zinc oxide nanoparticles

The toxicity of polystyrene nanoparticles (PS NPs) and ZnO nanoparticles (ZnO NPs), in combination is poorly known. Thus, the aim of the current study was to evaluate the effects of PS NPs (760 μg/L) on Ctenopharyngodon idella exposed to it, both in separate and in combination with ZnO NPs (760 μg/L), based on behavioral, biochemical and genotoxic biomarkers. Current data have indicated that PS NPs, for a short exposure period (3 days), both in separate and in combination with nanoparticles, have affected animals' response to the mirror test. On the other hand, all treatments have equally induced C. idella inactivity towards alarm substances and DNA damage. There was increased oxidative stress, mainly in groups exposed to PS NPs (in combination, or not, with nanoparticles); although increased, the evaluated antioxidant levels did not appear to be enough to inhibit the effects of treatment-induced production of free radicals. Together, these results are likely co-responsible for the observed changes. The current study did not observe antagonistic, synergistic or additive effect on animals exposed to the combination between PS NPs and ZnO NPs; however, this outcome should not discourage the performance of similar studies focused on assessing the (eco)toxicity of pollutant mixtures comprising nanomaterials.

Influence of IP-injected ZnO-nanoparticles in Catla catla fish: hematological and serological profile

This study reports an effort to synthesize biocompatible zinc oxide nanoparticles using sol-gel method and its influence on hematological and serological profile of Catla catla fish. Hexagonal wurtzite structure and crystallite size of ZnO-NPs was identified by using XRD in the range of 19 to 20 nm. Moreover, the irregular and non-uniform surface of these NPs was found using SEM. The different stretched and vibrational mode (ZnO, OH, CO, and H-O-H) was identified by using FTIR analysis. UV-visible spectroscopy confirmed absorbance of the blue shift in the range 340 nm. Bioassay of ZnO-NPs on Catla catla was performed and nano ZnO was given through intraperitoneal injections at 0, 25, 50, 75, and 100 μg/g body weight doses. Analysis of fish blood samples indicated an increase in WBCs and leukocytes while the differential effect on monocytes. On the other hand in response to varying ZnO concentrations, an increase in RBCs, hemoglobin, and HCT was evident. Serum analysis revealed an increase in urea concentration while a reduction in creatinine, ALT, and AST. In an overall assessment, nano-ZnO supplementation at 25 to 100 μg/g body weight differentially affected hematological and serum biochemical profile of thaila fish. Graphical abstract.

Predicting Cytotoxicity of Metal Oxide Nanoparticles using Isalos Analytics Platform

A literature curated dataset containing 24 distinct metal oxide (MexOy) nanoparticles (NPs), including 15 physicochemical, structural and assay-related descriptors, was enriched with 62 atomistic computational descriptors and exploited to produce a robust and validated in silico model for prediction of NP cytotoxicity. The model can be used to predict the cytotoxicity (cell viability) of MexOy NPs based on the colorimetric lactate dehydrogenase (LDH) assay and the luminometric adenosine triphosphate (ATP) assay, both of which quantify irreversible cell membrane damage. Out of the 77 total descriptors used, 7 were identified as being significant for induction of cytotoxicity by MexOy NPs. These were NP core size, hydrodynamic size, assay type, exposure dose, the energy of the MexOy conduction band (EC), the coordination number of the metal atoms on the NP surface (Avg. C.N. Me atoms surface) and the average force vector surface normal component of all metal atoms (v⟂ Me atoms surface). The significance and effect of these descriptors is discussed to demonstrate their direct correlation with cytotoxicity. The produced model has been made publicly available by the Horizon 2020 (H2020) NanoSolveIT project and will be added to the project's Integrated Approach to Testing and Assessment (IATA).

Effects of ZnO nanoparticles on the Giant freshwater prawn (Macrobrachium rosenbergii, de Man, 1879): Reproductive performance, larvae development, CHH concentrations and anti-oxidative enzymes activity

The Giant freshwater prawn (Macrobrachium rosenbergii) breeds when in captive conditions. The eggs of a clutch are attached to the abdomen of berried females. Zinc oxide (ZnO) is one of the most important metal oxide-nanoparticles (NPs) that is widely used in various industries and is released into aquatic environments from wastewater management facilities. The present study was conducted to evaluate effects of ZnO on values for the reproductive variables: larvae development, crustacean hyperglycemic hormone (CHH) release from the X-organ into the hemolymph and anti-oxidative enzymes activity of M. rosenbergii. There were five groups including a group not treated (control), and groups treated with10, 20, 50, 100 mg/L ZnO in triplicate during a 90-day period. Results indicated that ZnO-NPs have marked effects on reproductive performance, offspring development, CHH release from the X-organ into the hemolymph and anti-oxidant enzymes activities with there being no spawning of brood-stock in the 100 mg/L ZnO group and in the prawns treated with 50 mg/L there was spawning but there was larvae mortality immediately subsequent to hatching. Also, values for viability rate of eggs, dry weight of eggs, brood-stock inter-spawn period and egg clutch somatic index (ESI) reproductive variables were affected by the NP. This NP was found to have a dose-dependent effect on CHH release from the X-organ into the hemolymph and also superoxide dismutase (SOD) and catalase activities in M. rosenbergii. The results indicate that M. rosenbergii, a freshwater decapod crustacean, is an appropriate species to study nano-material effects on reproduction in freshwater ecosystems.

Hepatotoxic Effect of Oral Zinc Oxide Nanoparticles and the Ameliorating Role of Selenium in Rats: A histological, immunohistochemical and molecular study

Despite the emerging concerns about the hepatotoxic risks associated with Zinc oxide nanoparticles (ZnO NPs), yet, the morphological and molecular alterations associated with these extensively-used nanoparticles remain to be elucidated. Thus, the current study has been designed to analyze the effect of ZnO NPs on the hepatic histopathological and immunohistochemical changes, along with the modulation of the oxidative-stress induced JNK/p38MAPK and the STAT-3 signalling. The study also explored the potential protective role of selenium against those alterations. ZnO NPs disrupted the hepatic architecture, elevated the serum liver enzyme alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) levels and caused dose-dependent decrease in the activity of the antioxidant enzymes glutathione-peroxidase, superoxide dismutase and catalase along with an increase in the lipid peroxidation product malondialdehyde. ZnO NPs also increased the area of immune-reactivity of the apoptotic protein bax and decreased the area of immune-reactivity of the anti-apoptotic protein bcl2 together with augmentation of the hepatic caspase 3 gene expression. The role of selenium in ameliorating the hepatotoxicity, oxidative stress injury, and apoptosis induced by ZnO-NPs, along with its role in modulating the JNK/p38MAPK and the STAT-3 signalling and improving the histopathological hepatic changes, offers selenium as a promising adjunctive therapy in individuals subjected to high concentrations of ZnO NPs especially in cases of extensive occupational, medicinal and industrial exposure.

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.

Analysis of the Exposure of Organisms to the Action of Nanomaterials

The rapid development of the production of materials containing metal nanoparticles and metal oxides is a potential risk to the environment. The degree of exposure of organisms to nanoparticles increases from year to year, and its effects are not fully known. This is due to the fact that the range of nanoparticle interactions on cells, tissues and the environment requires careful analysis. It is necessary to develop methods for testing the properties of nanomaterials and the mechanisms of their impact on individual cells as well as on entire organisms. The particular need to raise public awareness of the main sources of exposure to nanoparticles should also be highlighted. This paper presents the main sources and possible routes of exposure to metal nanoparticles and metal oxides. Key elements of research on the impact of nanoparticles on organisms, that is, in vitro tests, in vivo tests and methods of detection of nanoparticles in organisms, are presented.

On how environmental and experimental conditions affect the results of aquatic nanotoxicology on brine shrimp (Artemia salina): A case of silver nanoparticles toxicity

The genus Artemia sp. has been accepted as a reliable model organism for aquatic toxicity and nanotoxicity experiments, as far as the ISO TS 20787 has recently been published to standardize nanotoxicity test with this organism. Experimental and environmental conditions may affect the toxicity of nanomaterials on aquatic organisms including Artemia sp. nauplii. In this study, acute toxicity effects of silver nanoparticles (AgNPs) on the nauplii of Artemia salina was investigated under various conditions (e.g. different lights, salinities, temperatures, volume and agitation of exposure media and instar stages of nauplii). The EC values were calculated using Probit program and all data were analyzed statistically by SPSS software. At all test conditions, the immobilization rate of Artemia nauplii increased in a concentration-dependent manner (P < 0.05). The sensitivity of instar stage II to different concentrations of AgNPs was significantly higher than instar I (P < 0.05). The toxicity effect of AgNPs was affected by alteration of environmental conditions, so that the effective concentration (EC) values for instar I of A. salina decreased with increasing water temperature, decreasing water salinity and in continuous darkness condition. The EC₅₀ value of AgNPs was significantly lower in 100 mL beakers (21.35 ± 5.67 mg L^-1) than 10 mL well plates (42.44 ± 11.30 mg L^-1). Agitation of exposure media did not affect the toxicity of AgNPs. The results indicated that the experimental and environmental conditions influence on the toxicity of AgNPs in the nauplii of A. salina.

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.

Understanding effect of solution chemistry on heteroaggregation of zinc oxide and copper oxide nanoparticles

The reported presence of mixture of nanoparticles in environmental water warrants developing understanding on their aggregation and fate. This study tried to address this question and focused on understanding effects of pH (3,7 and 10), background electrolyte concentration (1 mM and 10 mM as NaCl) and nanoparticle (NP) concentration (1 and 10 mg/L) on stability of suspension containing mixture of two commonly-found metal oxide-based NP (i.e., ZnO and CuO NPs) in a 6-h study (output variables: aggregation rate constant, settling rate constant, difference in zeta potential, change of metal content in suspension and on aggregates). Two iso-electric point values were obtained: pH 3.08 and 8.33 for mixture suspension in DI (De-ionized) water and pH 5.69 and 8.65 for mixture suspension with 10 mM electrolyte concentration. Settling rate constant and aggregation rate constant values of suspension containing mixture of NPs varied between 0.02 and 0.23 NTU/(NTU-hour) and 0.0002 and 0.03 nm/s, respectively. At natural pH condition, settling rate constant and aggregation rate constant values were obtained to be 0.05 NTU/(NTU- hour) and 0.012 nm/s. The Derjaguin-Landau-Verway-Overbeek (DLVO) analyses indicated that aggregation of mixture of NPs might be happening due to combined effects of ionic layer compression, charge neutralization and van der Waals attraction. Dissolution of nanoparticles was found to be significantly affected by change in pH of suspension. Stability of mixture of nanoparticles was observed to decrease with increasing pH, ionic strength and nanoparticle concentration values. For ZnO and CuO nanoparticles, model equations were developed for predicting their (i) aggregation rate constant, (ii) settling rate constant, (iii) difference in zeta potential, (iv) percentage change of metal in suspension and (v) solid Zn fractions of mixture of nanoparticles as a function of pH, ionic strength and NP concentration. These information are useful in understanding fate of mixture of NPs in suspension as well as in settled solids in natural water bodies and in water treatment systems.

Transcriptomic profile change, immunological response and disease resistance of Oreochromis niloticus fed with conventional and Nano-Zinc oxide dietary supplements

The present investigation was performed to evaluate the efficiency of Zinc oxide (ZnO) as a fish feed additive in immunomodulation of Oreochromis niloticus. Fish were fed on ZnO nano-particles (nZnO) and conventional (ZnO) in two concentrations (30 and 60 mg/kg diet), in addition to the control fish which was fed on Zn free diet. After 6° days, the highest survival rate was recorded in the nZnO₃₀ -supplemented group. The total antioxidant capacity (TAC) and antioxidant enzymes were improved in different dietary Zn supplementation, obviously in the nZnO₃₀ -supplemented group, while the lowest antioxidant status was noticed nZnO₆₀ supplemented fish. The lipid peroxides (MDA) level was diminished upon Zn supplementation, particularly in nZnO₃₀-supplemented group but showed a significant elevation in the nZnO₆₀-supplemented group. Furthermore, the immune parameters examined, lysozyme activity, bactericidal activity, and IgM were significantly higher in ZnO₆₀, and nZnO₃₀ supplemented groups. The C-reactive protein (CRP) level showed no significant increase in response to Zn supplementation in the both forms at level of 30 mg/kg diet, but showed marked elevation in nZnO₆₀- supplemented group. The mRNA expression profile of both interleukin 8 (IL-8), interleukin 1, beta (IL-1β) encoding genes showed an up-regulation that was found in all Zn- supplemented groups, but more pronounced in nZnO₆₀-supplemented group. On the other hand, the expression pattern of myxovirus resistance (Mx)-encoding gene showed no remarkable difference between the Zn- supplemented and control fish. The expression level of CXC-chemokine, toll-like receptor 7 (TLR-7), immunoglobulin M heavy chain (IgM heavy chain) and interferon gamma (IFN-γ) gene was upregulated in Zn-supplemented groups particularly in the nZnO₃₀- supplemented group. While, the lowest expression was found in nZnO₆₀- and ZnO₃₀-supplemented groups. Here, Zn supplementation promoted the immune and antioxidant strength in fish mainly in nano form at the level of 30 mg/kg diet but not at 60 mg/kg diet that disrupt the immune and antioxidant status and promote inflammatory response.

Will the antimicrobial properties of ZnONPs turn it into a more suitable option than AgNPs for water filtration? Comparative study in the removal of fish pathogen, Aeromonas hydrophila from the culture of juvenile common carp (Cyprinus carpio)

The purpose of this study was to investigate the possibility of using zinc oxide nanoparticles (ZnONPs) instead of silver nanoparticles (AgNPs) for removing Aeromonas hydrophila from water used to culture Cyprinus carpio juvenile. Antibacterial materials as filter media were prepared by coating ZnONPs (two coating methods, referred as ZnA and ZnB) or AgNPs (referred as Ag) on the porous surfaces of zeolite beads. The characterization of coated samples was determined using FESEM, EDS, and GFAAS. The antibacterial activities of prepared samples were evaluated by the zone of inhibition test, tube test, and flow test. The diameter of inhibitory zones formed by ZnONP- and AgNP-coated zeolite beads was significantly higher than uncoated zeolite (control) (P < 0.05). Also, the tube test results revealed 100% killing of the bacterial cells after 24 h of contact to all coated materials. In the flow test (without fish), the antibacterial efficiency of filter columns that contained ZnA, ZnB, and Ag found to be 34.84, 23.77, and 100% after 96 h, respectively. The mortality rate of carp juveniles cultured in infected water treated with AgNP filters was significantly lower than those cultured in infected water or treated with ZnONPs filters (P < 0.05). The results indicated that although ZnONP filter media have somewhat antimicrobial properties (especially in vitro), their ability to complete removal of microorganisms from the water is not as high as AgNP filters. So, it still seems that zeolite coated with AgNPs has a higher potential for water disinfection in aquaculture.

Analysis of ZnO nanoparticle-induced changes in Oreochromis niloticus behavior as toxicity endpoint

The toxicity of zinc oxide nanoparticles (ZnO NPs) has been investigated in different animal models. However, concentrations tested in most studies are often much higher than the ones potentially identified in the environment. Therefore, such toxicity limits the application of these studies to evaluate ecotoxicological risks posed by these nanopollutants. Thus, the aim of the current study is to evaluate the impacts of ZnO NPs (at environmentally relevant concentrations - 760 μg/L and 76,000 μg/L, for 72 h) on the behavioral responses of Oreochromis niloticus (Nile tilapia) exposed to it. Results did not evidence harmful effects of NPs on animals' locomotor abilities (evaluated through open-field and light-dark transition tests), or anxiety-predictive behavior. On the other hand, Zn bioaccumulation in the body tissues of the analyzed tilapias was correlated to changes in eating behavior (motivated by ration pellets), as well as to deficits in antipredatory defensive behavior (under individual and collective conditions). Tilapia exposed to ZnO NPs recorded lower avoidance, flight and territorialist behavior rates when they were individually confronted with potential predators (Salminus brasiliensis). However, collectively exposed animals were unable to recognize their predators, as well as to differentiate them from artificial baits ("false predators"). The present study is the first to report biological impacts resulting from the short exposure of fish-group representatives to ZnO NPs. Thus, we believe that it may be relevant to improve the knowledge about ecotoxicological risks posed by these pollutants.

Effects of food-borne ZnO nanoparticles on intestinal microbiota of common carp (Cyprinus carpio L.)

Ingestion of nanoparticles (NPs) with antimicrobial properties may disrupt the balance of intestinal microbiota. To investigate the effects of zinc oxide (ZnO) NPs on intestinal flora, common carp Cyprinus carpio were fed a commercial feed containing 500 mg kg^-1 ZnO NPs for 6 weeks and compared to a control group receiving a similar feed-only regime. Sequencing data were analyzed both in individual fish and in pooled samples. Sequencing of 16S rRNA encoding gene of individual specimens revealed high variation in intestinal microbial composition. Assessment of pooled results can obscure high individual variation in data. ZnO NPs consumption was not associated with a significant difference in the intestinal microbial community compared to untreated controls. Our results indicated a high individual variation in the intestinal microbiome, which may further point out the importance of functional study over microbial composition to address nanomaterials-microbiome relationship.

Antioxidant metabolism of zebrafish after sub-lethal exposure to graphene oxide and recovery

Graphene oxide (GO) is a carbon nanomaterial with specific properties, which allow its use in several areas. Some studies have characterized the effects of GO on aquatic organisms, but the ability of recovery after exposure remains largely unknown. In this study, we evaluated the effects of GO on the antioxidant metabolism of zebrafish after 48 h of sub-lethal exposure, and the fish recovery after 168 h in nanoparticle-free water. After the sub-lethal exposure, superoxide dismutase (SOD) activity was significantly increased in 20 mg L^-1, as well as catalase (CAT) activity in 2, 10, and 20 mg L^-1, and the lipid peroxidation (LPO) had an increase in 2 mg L^-1. On other hand, the glutathione peroxidase (GPx) activity was inhibited at 20 mg L^-1. After 168 h of recovery in clean water, the SOD activity remained significantly increased in 20 mg L^-1; the CAT activity was unchanged in all tested concentrations; the GPx activity was inhibited in 2, 10, and 20 mg L^-1; and the LPO significantly decreased in 2 mg L^-1. Our study suggests that GO exposure disrupts the antioxidant metabolism of adult zebrafish. Even after 168 h of recovery in clean water, homeostasis was not completely restored, although organisms developed mechanisms of recovery, and toxic effects were more subtle. Our results are pivotal to better understanding the physiological mechanisms involved in the detoxification process after GO exposure, and for strategies of protection on fish species.

Effects of Dietary Organic, Inorganic, and Nanoparticulate Zinc on Rainbow Trout, Oncorhynchus mykiss Larvae

The present study was conducted to investigate the effects of different dietary zinc sources on growth performance, survival, and body composition of larval rainbow trout, Oncorhynchus mykiss. A total of 3240 larvae with an average weight of 82.3 ± 11.6 mg were randomly divided into four groups by three replicates and were fed for 70 days. Organic zinc (Zn-proteinate, Bioplex Zn®), mineral zinc (ZnSO₄), and nanoparticulate zinc (ZnO-NPs) were each added to the basal diet at 50-mg/kg diet. In all of the zinc-supplemented groups, final body weight (FBW) and weight gain (WG) increased significantly (P < 0.05) compared to the control at the termination of the feeding trial. There was no significant difference in specific growth rate (SGR) in experimental groups. Fish fed with mineral and nanoparticulate zinc, respectively, demonstrated the highest and lowest survival rates (P < 0.05) as compared to other experimental diets. Feed conversion ratio (FCR) significantly decreased (P < 0.05) in groups fed with organic and mineral zinc. There were no significant differences in protein, lipid, moisture, and ash content among fish fed the experimental diets. Fish fed mineral zinc showed the highest (P < 0.05) zinc content in the whole body than the other groups. The data of the present study confirm positive effects of the use of 50 mg kg^-1 of zinc sources in early diet to enhance growth performance of rainbow trout larvae.

Dietary cosupplementation with curcumin and different selenium sources (nanoparticulate, organic, and inorganic selenium): influence on growth performance, body composition, immune responses, and glutathione peroxidase activity of rainbow trout (Oncorhynchus mykiss)

The aim of this study was to investigate the effects of dietary selenium (nanoparticles, organic, and inorganic forms), curcumin (CUR), and their combination on survival, growth performance, body composition, innate immune responses, and glutathione peroxidase activity of rainbow trout (Oncorhynchus mykiss). CUR at level of 400 mg/kg dry diet and each of selenium nanoparticles (Se-NPs), organic selenium (Sel-Plax®), and sodium selenite at level of 1 mg/kg Se dry diet were added to basal diet. A total of 240 rainbow trout with mean initial weight of 14.65 ± 0.86 g were fed eight diets including control (basal diet), CUR, Se-NPs, Se-NPs + CUR, organic Se, organic Se + CUR, sodium Se, and sodium Se + CUR for 8 weeks. No significant increase in survival rate, growth performance, feed utilization, and body composition was observed in fish-fed CUR and Se included diets compared to control (P > 0.05). The highest lysozyme and alternative hemolytic complement activity was observed in fish-fed CUR and organic Se + CUR-supplemented diets (P < 0.05). Fish-fed Se-NPs and Se-NPs + CUR-supplemented diets had the highest glutathione peroxidase activity (P < 0.05). The results of the present study indicated that the combination of CUR and Se in nanoparticles and organic forms was more effective in promoting innate immune responses of rainbow trout compared to the other combined or separated Se and CUR forms.

Comparative toxicity of silver nanoparticles (AgNPs) and silver nanowires (AgNWs) on saltwater microcrustacean, Artemia salina

This study evaluated the potential toxic effects of silver nanoparticles (AgNPs) and silver nanowires (AgNWs) on saltwater microcrustacean Artemia salina nauplii under ISO TS 20787 guideline. To investigate the acute toxicity of these nanomaterials, the nauplii were exposed to different concentrations of 0 (control), 0.39, 1.56, 6.25, 25 and 100 mg/L AgNPs and concentrations of 0 (control), 0.01, 0.1, 1, 10, 50 and 100 mg/L AgNWs for 72 h. Immobilization rate of A. salina exposed to both AgNPs and AgNWs for 72 h increased significantly in a concentration-dependent manner (P < 0.05). The 72 h EC₁₀ and EC₅₀ were found to be 1.48 ± 0.6 and 10.70 ± 1.3 mg/L for AgNPs, respectively, and 0.03 ± 0.02 and 0.43 ± 0.04 mg/L for AgNWs, respectively. Based on the EC₁₀ and EC₅₀ values, the toxicity of AgNWs was significantly higher than AgNPs (P < 0.05). Oxidative stress resulted from 48 h exposure to both AgNPs and AgNWs in A. salina was assessed by measuring reactive oxygen species (ROS) production and superoxide dismutase (SOD) activity. The results revealed that both AgNPs and AgNWs could induce ROS production. The SOD activity decreased significantly with the increase of exposure concentration (P < 0.05). In conclusion, the present results show that both nanomaterials have toxic effects on A. salina nauplii and thus, more effort should be made to prevent their release into saltwater ecosystems and trophic transfer in the aquatic food chain.

Trophic transfer of CuO nanoparticles from brine shrimp (Artemia salina) nauplii to convict cichlid (Amatitlania nigrofasciata) larvae: uptake, accumulation and elimination

We investigated the trophic transfer potential of CuO-NPs from Artemia salina to Amatitlania nigrofasciata. The Cu uptake was investigated by exposure of the instar II nauplii to 0, 1, 10, and 100 mg/L CuO-NPs for 4 h. Dietborne exposure of fish larvae to CuO-NPs was done for 21 days through feeding with pre-exposed nauplii. Thereafter, all survived fish were fed for 21 more days with non-contaminated nauplii. The results showed that NPs could be taken up by nauplii in a concentration-dependent manner. The highest uptake of Cu by nauplii was found to be 50.5 ± 1.4 mg/g dry weight at 100 mg/L. The copper accumulation in fish larvae increased significantly with increasing Cu content in pre-exposed nauplii to different concentrations of CuO-NPs (p < 0.05). At the end of the depuration phase, although the Cu elimination was significantly higher in fish that were fed with more contaminated nauplii, but the survival rate, average final weight, and length of those larvae was still significantly less than the control group (p < 0.05). The accumulated Cu after the depuration phase in cichlid larvae was 25.4 ± 0.5, 29 ± 8.0, 33.9 ± 9.7, and 42.3 ± 4.0 μg/g dry weight at 0, 1, 10, and 100 mg/L of CuO-NPs-treated Artemia. The current findings indicated the ability of manufactured CuO-NPs to be transferred from one trophic level to the next as assessed in the simple food chain consisting of pre-exposed A. salina and A. nigrofasciata.

Comparative toxicity of organic, inorganic and nanoparticulate zinc following dietary exposure to common carp (Cyprinus carpio)

This study was carried out to compare the dietary toxicity of organic zinc (Zn-proteinate, Bioplex Zn®), mineral zinc (ZnSO₄), and nanoparticulate zinc (ZnO-NPs) on the basis of some biological responses including growth performance and whole-body proximate composition, and antioxidant enzymes, as well as their accumulative affinity to target organs. These Zn sources with the nominal concentrations of 0, 30, 100, and 500 mg kg^-1 diet were added to a basal diet. Juvenile common carp (n = 400; weight of 25.3 ± 2.7 g) were fed with the diets for 56 days. ZnSO₄ significantly reduced condition factor (CF) at 500 mg kg^-1 diet. The highest activity of superoxide dismutase (SOD) and alkaline phosphatase (ALP) was observed in the plasma of the animals received 500 mg kg^-1 diet of all experimental Zn sources. However, this concentration of ZnO-NPs significantly increased the activity of SOD when compared to the respective amount of ZnSO₄ and Zn-proteinate. Catalase (CAT) showed a zinc-concentration decreasing activity; the minimum activity was observed in the fish group treated with the diet containing 500 mg kg^-1 ZnSO₄. Digestive, muscular, and integumentary systems demonstrated the following tissue zinc burden: liver > muscle > bone > posterior intestine ≈ skin > anterior intestine, for ZnO-NPs; liver > muscle ≈ bone ≈ posterior intestine ≈ skin > anterior intestine, for Zn-proteinate; and liver > muscle ≈ bone ≈ skin > posterior intestine ≈ anterior intestine, for ZnSO₄. Based on accumulative affinity, taken together, ZnO-NPs displayed the highest affinity to all of the analyzed target organs, and also intestinal Zn accumulation suggested that the gut tissue has the lowest rendering ability against ZnO-NPs in compare to ZnSO₄ and Zn-proteinate.