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

Antibiotic resistance in aquaculture and aquatic organisms: a review of current nanotechnology applications for sustainable management

Aquaculture has emerged as one of the world's fastest-growing food industries in recent years, helping food security and boosting global economic status. The indiscriminate disposal of untreated or improperly managed waste and effluents from different sources including production plants, food processing sectors, and healthcare sectors release various contaminants such as bioactive compounds and unmetabolized antibiotics, and antibiotic-resistant organisms into the environment. These emerging contaminants (ECs), especially antibiotics, have the potential to pollute the environment, particularly the aquatic ecosystem due to their widespread use in aquaculture, leading to various toxicological effects on aquatic organisms as well as long-term persistence in the environment. However, various forms of nanotechnology-based technologies are now being explored to assist other remediation technologies to boost productivity, efficiency, and sustainability. In this review, we critically highlighted several ecofriendly nanotechnological methods including nanodrug and vaccine delivery, nanoformulations, and nanosensor for their antimicrobial effects in aquaculture and aquatic organisms, potential public health risks associated with nanoparticles, and their mitigation measures for sustainable management.

Size-dependent biological effect of copper oxide nanoparticles exposure on cucumber (Cucumis sativus)

Copper oxide nanoparticles (CuO NPs) have received considerable attention for their toxic effects on crops and potential application in agriculture. In order to investigate the biological effects of CuO NPs on plants, we exposed cucumber (Cucumis sativus) to two sizes of CuO NPs (510 nm, μCuO and 43 nm, nCuO). Results indicated that with concentration increased, the available Cu content in soil increased significantly. The addition of CuO NPs increased Cu content and other nutrient element (e.g., K, P, Mn, and Zn) content in plants. However, diverse particle sizes had different effects. The nCuO treatment had larger translocation factor, higher nutrient element content in fruits, and lower oxidative damage than μCuO treatment. Moreover, nCuO of 100 mg/kg could stimulate cucumber growth, while μCuO had no obvious effects on growth. Conclusively, CuO NPs could be used as copper fertilizer to supply copper to cucumber. The nCuO had better effects on improving the bioavailability of Cu and nutritional value of fruits. These results can help develop strategies for safe disposal of CuO NPs as agricultural fertilizer.

Behavior and toxicity assessment of copper nanoparticles in aquatic environment: A case study on red swamp crayfish

With the wide use of copper nanoparticles (CuNPs) in various industrial and commercial applications, they inevitably enter the aquatic environment. However, their behavior in the aquatic environment and potential toxicity to aquatic organisms remain little known. In this study, we investigated the behavior of CuNPs in freshwater, as well as the toxicity and bioaccumulation of CuNPs and copper sulfate (CuSO₄), used as a positive control for copper ions toxicity, in red swamp crayfish (Procambarus clarkii). The results showed that CuNPs released copper ions into freshwater and aggregated rapidly in freshwater, and their release of copper ions and aggregation slowed down at a higher concentration of CuNPs. The calculated 72-h LC₅₀ values for crayfish were 1.18 and 0.54 mg/L for CuNPs and CuSO₄, respectively. Cu accumulation in the gill and hepatopancreas from CuSO₄ treatments was significantly higher than that from CuNPs, and the highest Cu bioaccumulation level in crayfish was found in the gill, followed by hepatopancreas and muscle with the exposure of copper. The activities of the antioxidative enzymes in the crayfish significantly decreased after exposure to CuNPs for 48 h, compared to the control (without CuNPs or CuSO₄). Histological examination revealed that there was no significant alteration of hepatopancreas in the crayfish exposed to CuNPs. Meanwhile, the growth of crayfish was not significantly inhibited by CuNPs. These results suggested that CuNPs exposure can induce oxidative stress in the crayfish, gill is the main tissue for their accumulation, and their toxicity is mainly caused by the released copper ions.

Impacts of four commonly used nanoparticles on the metabolism of a marine bivalve species, Tegillarca granosa

The rapid development of nanotechnology boosts the massive production and utilization of various nanoparticles (NPs). However, the NPs escaped into environments form emergent pollutants, which pose a potential threat to marine organisms and ecosystems. Due to their sessile filter-feeding lifestyle, marine bivalves live in pollution-prone coastal areas are more susceptible to land-sourced pollutants such as NPs. However, the impacts of many NPs on the metabolism, one of the most critical physiological processes of an organism, still remain largely unknown in bivalve species. To fill up this knowledge gap, in this study the impacts of four commonly used NPs (nZnO, nFe₂O₃, nCuO, and multi-walled carbon tube (MWCNT)) on the filtration rate, oxygen consumption rate, ammonia excretion rate, and O:N ratio were investigated in the blood clam, Tegillarca granosa. In addition, the expressions of ten key metabolism-related genes upon exposure to these NPs were also analyzed. The results demonstrated that exposure of blood clams to the NPs resulted in a reduction in the food intake (indicated by declined filtration rate), a shift in the metabolism substance, and disruptions in key metabolism-related molecular pathways (i.e., glycolysis and tricarboxylic acid cycle), which may render blood clam in energy shortage and thus pose significant threat to the health of this important bivalve species.

X-ray spectrometry imaging and chemical speciation assisting to understand the toxic effects of copper oxide nanoparticles on zebrafish (Danio rerio)

Currently, copper nanoparticles are used in various sectors of industry, agriculture, and medicine. To understand the effects induced by these nanoparticles, it is necessary to assess the environmental risk and safely expand their use. In this study, we evaluated the toxicity of copper oxide (nCuO) nanoparticles in Danio rerio adults, their distribution/concentration, and chemical form after exposure. This last assessment had never been performed on copper-exposed zebrafish. Such evaluation was done through the characterization of nCuO, acute exposure tests and analysis of distribution and concentration by microstructure X-ray fluorescence spectroscopy (µ-XRF) and atomic absorption spectroscopy (GF-AAS). Synchrotron X-ray absorption spectroscopy (XAS) was performed to find out the chemical form of copper in hotspots. The results show that the toxicity values of fish exposed to nCuO were 2.4 mg L^-1 (25 nm), 12.36 mg L^-1 (40 nm), 149.03 mg L^-1 (80 nm) and 0.62 mg L^-1 (CuSO₄, used as a positive control). The total copper found in the fish was in the order of mg kg^-1 and it was not directly proportional to the exposure concentration; most of the copper was concentrated in the gastric system. However, despite the existence of copper hotspots, chemical transformation of CuO into other compounds was not detected.

Effect of Copper Nanoparticles and Ions on Epididymis and Spermatozoa Viability of Chinese Soft-Shelled Turtles Pelodiscus sinensis

Copper nanoparticles (CuNPs) have been widely used in various industrial and commercial applications, which become a potential threat to aquatic organisms. Nevertheless, their potential toxicity to the epididymis and sperm remains little known. In this study, we evaluated the effect of CuNPs and copper ions (CuSO4) on the spermatozoa viability, epididymal structure, antioxidant enzyme activity, and inflammatory cytokines in cauda epididymis of the Chinese soft-shelled turtle. Results showed that the spermatozoa viability of Chinese soft-shelled turtles decreased significantly with an increase in CuNPs or Cu ions concentrations. The epithelial cells of the epididymal duct of the Chinese soft-shelled turtles with the treatment of 5 mg kg−1 CuNPs were slightly swollen, and the connective tissue between the epididymal ducts was loose. The epithelial structure of the epididymal tube was severely damaged with an increase in Cu ion concentrations. Compared to the control, the antioxidative enzymes activities and the expression of IL-1β, TNF-α, and IL-6 mRNA in the epididymis significantly increased with the treatment of CuNPs or CuSO4. The present study revealed that Cu ions exert more harmful effect on the epididymis and spermatozoa viability of Chinese soft-shelled turtles than copper nanoparticles.

Cell and tissue level responses in mussels Mytilus galloprovincialis dietarily exposed to PVP/PEI coated Ag nanoparticles at two seasons

Silver nanoparticles (Ag NPs) are present in numerous consumer products due to their antimicrobial and other unique properties, thus concerns about their potential input into aquatic ecosystems are increasing. Toxicity of Ag NPs in waterborne exposed aquatic organisms has been widely investigated, but studies assessing the potential toxic effects caused after ingestion through the food web, especially at low realistic concentrations, remain scarce. Moreover, it is not well known whether season may influence toxic effects of Ag NPs. The main objective of this study was to determine cell and tissue level responses in mussels Mytilus galloprovincialis dietarily exposed to poly-N-vinyl-2-pirrolidone/polyethyleneimine (PVP/PEI) coated 5 nm Ag NPs for 1, 7 and 21 days both in autumn and spring. Mussels were fed every day with microalgae Isochrysis galbana exposed for 24 h to a low dose (1 μg Ag/L Ag NPs) in spring and to a higher dose (10 μg Ag/L Ag NPs) in spring and autumn. Mussels fed with microalgae exposed to the high dose accumulated Ag significantly after 21 days in both seasons, higher levels being measured in autumn compared to spring. Intralysosomal metal accumulation measured in mussel digestive gland and time- and dose-dependent reduction of mussels health status was similar in both seasons. DNA strand breaks increased significantly in hemocytes at both exposure doses along the 21 days in spring and micronuclei frequency showed an increasing trend after 1 and 7 days of exposure to 1 μg Ag/L Ag NPs in spring and to 10 μg Ag/L in both seasons. Values decreased after 21 days of exposure in all the cases. In conclusion, PVP/PEI coated 5 nm Ag NPs ingested through the food web were significantly accumulated in mussel tissues and caused adverse cell and tissue level effects both in autumn and in spring.

Can Proteomics Be Considered as a Valuable Tool to Assess the Toxicity of Nanoparticles in Marine Bivalves?

Exposure to nanoparticles (NPs) has been identified as a major concern for marine ecosystems. Because of their peculiar physico-chemical features, NPs are accumulated in marine organisms, which suffer a variety of adverse effects. In particular, bivalve mollusks represent a unique target for NPs, mainly because they are suspension-feeders with highly developed processes for cellular internalization of nano- and micrometric particles. Several studies have demonstrated that the uptake and the accumulation of NPs can induce sub-lethal effects towards marine bivalves. However, to understand the real risk of NP exposures the application of the so-called “omics” techniques (e.g., proteomics, genomics, metabolomics, lipidomics) has been suggested. In particular, proteomics has been used to study the effects of NPs and their mechanism(s) of action in marine bivalves, but to date its application is still limited. The present review aims at summarizing the state of the art concerning the application of proteomics as a tool to investigate the effects of nanoparticles on the proteome of marine bivalves, and to critically discuss the advantages and limitations of proteomics in this field of research. Relying on results obtained by studies that applied proteomics on bivalve tissues, proteomics application needs to be considered cautiously as a promising and valuable tool to shed light on toxicity and mechanism(s) of action of NPs. Although on one hand, the analysis of the current literature demonstrated undeniable strengths, potentiality and reliability of proteomics, on the other hand a number of limitations suggest that some gaps of knowledge need to be bridged, and methodological and technical improvements are necessary before proteomics can be readily and routinely applied to nanotoxicology studies.

Effect of ageing of bare and coated nanoparticles of zinc oxide applied to soil on the Zn behaviour and toxicity to fish cells due to transfer from soil to water bodies

This study evaluated the influence of ageing of ZnO nanoparticles (NPs) applied to soil on the potential availability and chemical speciation of Zn, and also of their toxicity to aquatic organisms due to transfer of contaminants from soil to water. To this end, soil samples were spiked with two types of bare nanoparticles: b1ZnO NPs (rod- and elongated-shaped) and b2ZnO NPs (near-spherical shaped) and ZnO NPs coated with (3-aminopropyl)triethoxysilane (cZnO NPs) within the 0-800 mg Zn kg^-1 soil dose range, and were left to age for 0, 30, 60 and 90 days. The available concentration and speciation of Zn in soil were determined by the DGT (diffusive gradients in thin films) technique and sequential extraction procedures, respectively. The toxicity of the aqueous extracts from the ZnO NP-treated soils was assessed in vitro in established fish cell lines (RTG-2). The highest distribution percentages of the applied Zn occurred in the organically complexed (OC), followed by the exchangeable (EXC) fraction, for all NP types, applied doses and incubation times. The toxicity of NPs depended on their intrinsic properties: b1ZnO NPs affected the membrane function, reductase enzyme activity and, to a lesser extent, reactive oxygen species (ROS) levels of fish cells, whereas b2ZnO NPs and cZnO NPs affected mainly ROS generation. Ageing increased Zn soil availability, but toxicity to fish cells showed no trend over time. The particle dissolution of ZnO NPs did not explain the observed toxicity, hence a nanoparticles-specific effect should be assumed. The findings of this study seem to indicate that the transfer of ZnO NP from contaminated soils to aquatic ecosystems should be addressed.

Immunotoxicity of four nanoparticles to a marine bivalve species, Tegillarca granosa

The increasing application of nanomaterials drives the unintentional release of nanoparticles (NPs) into the ocean, which may pose a potential threat to marine organisms. It has been demonstrated that exposure to NPs could chanllenge the immune responses of marine species. However, the affecting mechanism behind remains poorly understood. In this study, the immunotoxic impacts and the mechanisms underpinning the effects of four major NPs, including nZnO, nFe₂O₃, nCuO, and carbon nanotube (MWCNT), were investigated in blood clam, Tegillarca granosa. The results showed that exposure to tested NPs resulted in reduced total counts, altered cell composition, and constrained phagocytic activities of haemocytes. The intracellular contents of reactive oxygen species (ROS) and the degree of DNA damage of haemocytes were significantly induced, whereas the haemocyte viability was suppressed. Furthermore, NP exposures led to significant increases in the in vivo contents of neurotransmitters. Down-regulations of the immune- and neurotransmitter-related genes were detected as well. Our data suggest that NP exposures hampered the immune responses of blood clams most likely through (1) inducing ROS, causing DNA damage, and reducing cell viability of haemocytes, (2) altering the in vivo contents of neurotransmitters, and (3) affecting the expression of immune- and neurotransmitter-related genes.

Comparative contributions of copper nanoparticles and ions to copper bioaccumulation and toxicity in barnacle larvae

Cu nanoparticles (CuNPs) have been widely used in numerous products, and may become a potential threat to marine organisms, but their behavior in the marine environments and potential toxicity to marine organisms remain little known. In the present study, we investigated the behavior of CuNPs in seawater, as well as the toxicity and bioaccumulation of CuNPs and copper sulfate (CuSO₄) in barnacle larvae (Balanus amphitrite), a dominant fouling invertebrate in marine environment. CuNPs tended to aggregate in natural seawater and released Cu ion rapidly into seawater. The aggregation and release were especially higher at a lower concentration of CuNPs, e.g., 94-96% of CuNPs were released as Cu ions at 20 μg/L after 24 h. The larger size of CuNPs (40 nm) tended to display a higher solubility than the 20 nm CuNPs did. Humic acids enhanced the aggregation and inhibited the dissolution of CuNPs, and had a protective effect on the survival of nauplii II at higher Cu concentrations (100-200 μg/L). Comparison of the lethal concentrations showed that CuNPs were generally less toxic to the two stages of barnacle larvae (nauplii II and VI) than the Cu ions. The calculated 48-h LC₅₀ values for nauplii II were 189.5 μg/L, 123.2 μg/L, and 89.8 μg/L for 20 nm CuNPs, 40 nm CuNPs, and CuSO₄, respectively. However, the lethal concentrations of Cu bioaccumulation in the barnacle larvae were comparable between CuNPs and Cu ions when expressed by the actual tissue Cu bioaccumulation. Barnacle larval settlement decreased with an increase of Cu concentrations of both CuNPs and CuSO₄, and was significantly inhibited at 100 μg/L CuSO₄ and 150 μg/L CuNPs. Our results indicated that the toxicity of CuNPs could not be solely explained by the released Cu ions, and both CuNPs and the released Cu ion contributed to their toxicity and bioaccumulation in barnacle larvae.

Corbicula fluminea gene expression modulated by CeO2 nanomaterials and salinity

Cerium dioxide nanomaterials (CeO₂ NMs) are used in different fields and incorporated in daily products. Several studies highlighted their effects on organism physiology, although molecular studies remain scarce. NM behavior is strongly dependent on the environment but few data are available using complex exposure media, raising the question of its environmental impacts. The aim of the present work was to assess the toxic potential of three CeO₂ NMs in Corbicula fluminea at a molecular level by RT-qPCR under a more realistic scenario of exposure, in a multistress context at two different salinities (1.5 and 15 psu). C. fluminea was exposed for 28 days to pulses of the three selected NMs (reference, manufactured, and aged manufactured). In bivalves, the gills and digestive gland are two key organs used for ecotoxicological studies. The expression change of 12 genes was measured in control organisms after 28 days in both organs, allowing us to clearly separate the responses for both organs and salinities. As gills come in contact with the environment first, we monitored gene the expression at intermediate time points (7, 14, and 21 days) for this organ in order to highlight clams responses to NM and salinity. Two genes (Se-GPx, MnSOD) had a salinity-dependent level of expression. HSP70, Se-GPx, and Trxr mRNAs presented significant changes in their expressions in the presence of NM. This study was completed using an integrated statistical approach. The exposed organisms differed more from control at field salinity than those exposed to hyper-saline conditions. At 15 psu, salinity pressure seems to cause the first molecular impact. At 1.5 psu, gene expression patterns allowed the effect of each NM to separate clearly. These results confirmed the usefulness of gene expression studies. Moreover, we highlighted the necessity to assess the environmental toxicity of the different forms of manufactured NM.

Dietary exposure of mussels to PVP/PEI coated Ag nanoparticles causes Ag accumulation in adults and abnormal embryo development in their offspring

Toxicity of silver nanoparticles (Ag NPs) to aquatic organisms has been widely studied. However, the potential toxic effects of Ag NPs ingested through the food web, especially at environmentally relevant concentrations, as well as the potential effects on the offspring remain unknown. The aims of this work were to screen the cytotoxicity of Poly N‑vinyl‑2‑pirrolidone/Polyethyleneimine (PVP/PEI) coated 5 nm Ag NPs in hemocytes exposed in vitro and to assess the effects of dietary exposure to Ag NPs on mussels growth, immune status, gonad condition, reproductive success and offspring embryo development. For this, mussels Mytilus galloprovincialis were fed daily with microalgae Isochrysis galbana previously exposed for 24 h to a dose close to environmentally relevant concentrations (1 μg Ag/L Ag NPs) and to a high dose of 10 μg Ag/L Ag NPs. After 24 h of in vitro exposure, Ag NPs were cytotoxic to mussel hemocytes starting at 1 mg Ag/L (LC50: 2.05 mg Ag/L). Microalgae significantly accumulated Ag after the exposure to both doses and mussels fed for 21 days with microalgae exposed to 10 μg Ag/L Ag NPs significantly accumulated Ag in the digestive gland and gills. Sperm motility and fertilization success were not affected but exposed females released less eggs than non-exposed ones. The percentage of abnormal embryos was significantly higher than in control individuals after parental exposure to both doses. Overall, results indicate that Ag NPs taken up through the diet can significantly affect ecologically relevant endpoints such as reproduction success and embryo development in marine mussels.

Assessing the effect of human pharmaceuticals (carbamazepine, diclofenac and ibuprofen) on the marine clam Ruditapes philippinarum: An integrative and multibiomarker approach

The presence of pharmaceuticals in the aquatic ecosystem has become a topic of growing interest in recent years. In this study, the marine clam Ruditapes philippinarum was exposed during 14 days to concentrations close to those found in the environment: (15 μg L^-1) of carbamazepine (CBZ), diclofenac (DCF) and ibuprofen (IBU), three pharmaceuticals widely used worldwide and commonly found within the aquatic environment. Additionally, exposure was followed by a depuration phase (7 days). A battery of biomarkers (superoxide dismutase SOD, catalase CAT, glutathione reductase GR, total glutathione peroxidase T-GPx, glutathione transferase GST, lipid peroxidation LPO, acetylcholinesterase AChE and metallothionein MT) was evaluated throughout the exposure and depuration. The Integrated Biomarker Response index was calculated with all selected biomarkers and used as a complementary tool in the evaluation of the organisms' health status. Exposure induced changes in the clams' biochemical responses that led to the hypothesis of the harmful role of the pharmaceuticals resulting in negative effects (changes in enzyme activities, LPO and MT levels, related to ROS production) particularly after short-term exposure. However, the clams showed the ability to cope with these imbalances by recovering their general oxidative status by the end of exposure.

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

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