Induction of oxidative stress and apoptosis by silver nanoparticles in the liver of adult zebrafish

Evaluation of the Ameliorative Effect of Zinc Nanoparticles against Silver Nanoparticle-Induced Toxicity in Liver and Kidney of Rats

Silver nanoparticles (Ag-NPs) have various pharmaceutical and biomedical applications owing to their unique physicochemical properties. Zinc (Zn) is an essential trace element, a strong antioxidant, and has a primary role in gene expression, enzymatic reactions, and protein synthesis. The present study aims to explore the toxic effects of Ag-NPs (50 nm) on the liver and kidney of rats and also to evaluate the potential protective effect of Zn-NPs (100 nm) against these adverse effects. Forty adult Sprague-Dawley rats were randomly divided into four equal groups: control group, Ag-NPs group, Zn-NPs group, and Ag-NPs + Zn-NPs group. Ag-NPs (50 mg/kg) and/or Zn-NPs (30 mg/kg) were administered daily by gavage for 90 days. The results showed that exposure to Ag-NPs increased serum ALT, AST, urea, and creatinine. Ag-NPs also induced oxidative stress and lipid peroxidation and increased inflammatory cytokines in hepatic and renal tissues. Moreover, histopathological and immunohistochemical examinations revealed various histological alterations and positive caspase-3 expressions in the liver and kidney following exposure to Ag-NPs. On the other hand, most of these toxic effects were ameliorated by co-administration of Zn-NPs. It was concluded that Ag-NPs have hepatotoxic and nephrotoxic effects in rats via different mechanisms including oxidative stress, inflammation, and apoptosis and that Zn-NPs can be used to alleviate these harmful effects by their antioxidative, anti-inflammatory, and antiapoptotic properties.

Albicanol modulates oxidative stress and the p53 axis to suppress profenofos induced genotoxicity in grass carp hepatocytes

The organophosphorus pesticide profenofos (PFF) is widely used as an environmental contaminant, and it can remain in water bodies causing serious harm to aquatic organisms. Albicanol is a sesquiterpenoid with potent antioxidant and antagonistic activities against heavy metal toxicity. However, the mechanism of PFF induced genotoxicity in fish hepatocytes and the role Albicanol can play in this process are unknown. In this study, the model was established by treating grass carp hepatocytes with PFF (150 μM) and/or Albicanol (5 × 10^-5 μg mL^-1) for 24 h. The results showed that PFF exposure arrested L8824 cells in the G1-S phase. PFF caused the increase of MDA level in L8824 cells, while the decrease of SOD, CAT and T-AOC levels caused oxidative stress. Elevated levels of γH2AX, tail moment, tail length, % DNA and 8-OHdG indicated that PFF caused DNA damage in L8824 cells. PFF inhibited the expression levels of cell cycle related regulatory genes (cyclin A, cyclin D, cyclin E, CDK2 and CDK4) by upregulating p53/p21 genes and activating the p53 signaling pathway. Albicanol was used to significantly reduce the above effects caused by PFF exposure on hepatocytes in grass carp. Albicanol could reduce the increase in the proportion of cells in the G1-S phase caused by PFF. In summary, Albicanol could inhibit the genotoxicity of L8824 cells resulted from PFF exposure by decreasing oxidative stress and the p53 pathway.

Effects of chlorobromoisocyanuric acid on embryonic development and immunotoxicity of zebrafish

Although chlorobromoisocyanuric acid has been widely used in agriculture, its deleterious toxicity on aquatic organisms remains rare. In this study, zebrafish were exposed to chlorobromoisocyanuric acid (0, 30, 40, and 50 mg/L) from 10 to 96 h post-fertilization (hpf). We found a significant reduction in immune cell numbers (neutrophils and macrophages) and the area of thymus at 96 hpf. The expression of immune-related genes and pro-inflammatory cytokines genes were upregulated. Besides, chlorobromoisocyanuric acid triggered neutrophils cell apoptosis. The mRNA and protein levels of pro-apoptotic p53 pathway and the Bax/Bcl-2 ratio further indicated the underlying mechanism. Furthermore, the oxidative stress was observed that the accumulation of reactive oxygen species and malondialdehyde significantly increased. Subsequently, the antioxidant agent astaxanthin significantly attenuated the level of oxidative stress and the dysregulation of inflammatory response. In summary, our results showed that chlorobromoisocyanuric acid induced developmental defects and immunotoxicity of zebrafish, partly owing to oxidative stress and cell apoptosis.

Environmental Risk Assessment of Oxaliplatin Exposure on Early Life Stages of Zebrafish (Danio rerio)

Pharmaceuticals are actually identified as a threat to the ecosystem. Nowadays, the growing consumption of antineoplastic agents has been related to their continuous input in natural environments. These substances can interfere with physiological and biochemical processes of aquatic species over their entire life cycle. Oxaliplatin (OXA) is a widely used chemotherapeutic agent to treat colon or rectal cancer. This study was aimed to evaluate the developmental toxicity of the OXA exposure. To this end, zebrafish embryos were incubated with 0.001, 0.1, 0.5 mg/L OXA. At different timepoints mortality rate, hatching rate, developmental abnormalities, histological analysis, oxidative stress and mRNA expression of gene related to oxidative stress were evaluated. Our results showed that OXA exposure can induce increased mortality and developmental abnormalities reducing the hatching rate. Histological analysis demonstrated that OXA induced liver, intestine, muscle and heart injury. Superoxide dismutase and catalase activities were significantly increased after OXA exposure demonstrating its oxidative effects. The mRNA expression levels of apoptosis-related genes (caspase-3, bax and bcl-2) were significantly upregulated by OXA exposure. In conclusion, we highlighted that OXA exposure led to a dose-related developmental toxicity, oxidative stress and apoptosis.

Microplastic-induced apoptosis and metabolism responses in marine Dinoflagellate, Karenia mikimotoi

Microplastics (MPs) occur widely in marine environments, and disturb the balance of aquatic ecosystems. In this study, programmed cell apoptosis in marine dinoflagellate, Karenia mikimotoi exposed to 10 mg L^-1 micro/nanoplastics (MPs/NPs; polystyrene and polymethyl methacrylate) for 72 h was assessed. Prior to the toxicity assay, MPs/NPs were dialyzed to remove possible additives. Cell viability, membrane integrity, cell apoptosis, and total DNA concentration were measured to assess programmed cell apoptosis in K. mikimotoi following exposure to MPs/NPs. A transcriptome analysis was used to explore the potential toxic mechanism of MPs to K. mikimotoi. Programmed cell apoptosis was related to the size of MPs/NPs, and NPs could more easily impair cell viability, and reduced cell membrane integrity and DNA concentration. NP particles caused continuous apoptosis of K. mikimotoi compared to MP particles. Size had the greatest effect on toxicity in K. mikimotoi. In conclusion, the results evidenced that both MPs and NPs have a negative impact on the marine dinoflagellate, K. mikimotoi. However, NPs were more harmful to K mikimotoi than MPs, highlighting the potential ecological problems associated with exposure to NPs.

Ecotoxicological Effects of Silver Nanoparticles (Ag-NPs) on Parturition Time, Survival Rate, Reproductive Success and Blood Parameters of Adult Common Molly (Poecilia sphenops) and Their Larvae

Nanoparticles (NPs) can display toxicological effects on aquatic organisms. This study investigates ecotoxicological effects of Ag-NPs on reproductive and blood parameters of adult common molly (Poecilia sphenops) and their larvae. During the LC50 96 h test, female fish were exposed to concentrations of 0, 5, 15, 25, 35, 45 and 60 mg L−1 of Ag-NPs, while larvae were exposed to 0, 3, 5, 10 and 15 mg L−1. Finally, we aim to evaluate the effects of 0, 5, 10 and 15 mg L−1 of Ag-NPs on parturition time, reproductive success and hematological parameters of the mature fish exposed to sub-lethal concentration during a 62-day period. We also evaluated the survival rate of larvae. The results show a positive correlation between mortality rate and Ag-NP concentration. Values for LC50 96 h in adult fish and larvae were 26.85 mg L−1 and 6.22 mg L−1, respectively. A lack of parturition and reproductive success were seen in fish that underwent chronic exposure to Ag-NPs (15 mg L−1). The results show that RBC, WBC and hematocrit were significantly decreased in fish exposed to Ag-NPs. In addition, the serum concentrations of total protein, albumin, cholesterol and triglycerides were significantly increased in fish submitted to Ag-NPs (concentrations of 5–15). In conclusion, submitting a fish to higher concentration than 10 mg L−1 has adverse effects on reproductive system and blood parameters.

Ecotoxicological assessment of spent battery extract using zebrafish embryotoxicity test: A multi-biomarker approach

Water environmental pollution caused by spent batteries is a nonignorable environmental issue. In this study, the early life stage of zebrafish was employed to assess the environmental risk of spent batteries after exposure to 0, 1%, 2%, 5% and 10% spent battery extract for 120 h. Our results clearly indicated that spent battery extract can significantly decrease the survival rate, hatching rate and body length and increase heart rate. Moreover, spent battery extract exposure-induced zebrafish larvae generate oxidative stress and inhibit the mRNA transcriptional levels of heat shock protein (HSP70) and metallothionein (MT) genes. These results showed that the spent batteries not only affected the survival and development performance of zebrafish at an early life stage but also caused oxidative stress and interfered with the detoxification of zebrafish. This study provided novel insight into spent battery induced toxicity in the early life stage of fish.

Impact of underwater noise on the growth, physiology and behavior of Micropterus salmoides in industrial recirculating aquaculture systems

The operation of the equipment in industrial recirculating aquaculture systems (RAS) affects the underwater soundscape of aquaculture tanks where fishes live. This study evaluated the influence of commercial industrial RAS noise on the growth, physiology, and behavior of juvenile largemouth bass (Micropterus salmoides). In this study, two experimental groups, the RAS noise group (115 dB re 1 μPa RMS) and the ambient group (69 dB re 1 μPa RMS), were studied. The water quality and feeding regime for each group were kept the same during the 60-day experiment. Results showed that there was no significant difference in the average daily feed intake of the fish between the two treatments, while the rate of weight gain of the ambient group (755.27 ± 65.62%) was significantly higher than that of the noise group (337.66 ± 88.01%). In addition, the RAS environmental noise also had an adverse effect on the anti-oxidation and immune systems of the fish based on results of analysis of blood, liver, and intestinal samples. Moreover, environmental noise affected the swimming behavior of the fish school. The mean angle and distance between the focal fish and its nearest neighbor fish in RAS noise group were 33.3° and 92.1 mm, respectively, which were larger than those of the ambient group with 24.4° and 89.5 mm, respectively. From the above results, RAS noise did influence the welfare of largemouth bass, and the soundscape in RAS hence should be managed in real production.

A Multi-Life Stage Comparison of Silver Nanoparticle Toxicity on the Early Development of Three Canadian Fish Species

Information on the effects of silver nanoparticles (AgNPs) in fish has mostly been generated from standard laboratory species and short-term toxicity tests. However, there is significant uncertainty regarding AgNP toxicity to native species of concern in North America, particularly in northern freshwater ecosystems. We assessed the chronic toxicity of AgNPs in early life stages of three North American fish species: rainbow trout (Oncorhynchus mykiss), lake trout (Salvelinus namaycush), and northern pike (Esox lucius). Newly fertilized embryos were exposed to nominal aqueous concentrations of 0.1, 0.3, 1.0, 3.0, 10.0, or 30.0 nM AgNPs for 126 (rainbow trout), 210 (lake trout), and 25 (northern pike) days. Endpoints included cumulative developmental time (°C × day or degree-days to 50% life-stage transition), mortality, fork length, embryonic malformations, cumulative survival, and histopathology of gill and liver in larvae/alevins. The results showed life stage-specific differences in responses, with endpoints during the embryonic stage occurring more often and at lower concentrations compared to larval/alevin and juvenile stages. Sensitivities among species were highly dependent on the endpoints measured, although developmental time appeared to be the most consistent endpoint across species. At embryonic and larval/alevin stages, northern pike was the most sensitive species (lowest observable effect concentration of 0.1 nM using developmental time). Rainbow trout displayed similar responses to lake trout across multiple endpoints and therefore seems to be an adequate surrogate for trout species in ecotoxicology studies. Moreover, while mortality during individual life stages was not generally affected, the cumulative mortality across life stages was significantly affected, which highlights the importance of chronic, multi-life-stage studies. Environ Toxicol Chem 2021;40:3337-3350. © 2021 SETAC.

Dietary supplementation with curcumin nanomicelles, curcumin, and turmeric affects growth performance and silver nanoparticle toxicity in Cyprinus carpio

An 8-week feeding experiment was conducted to investigate the effects of curcumin nanomicelle, curcumin, and turmeric (Curcuma longa) on growth performances, body composition, fatty acid profile, and biochemical parameters of common carp (Cyprinus carpio), and their ameliorative effects against toxicity of silver nanoparticles (AgNPs). A total of 120 healthy carps were randomly distributed into four equal treatments. Curcumin nanomicelle, curcumin, and turmeric were each added separately to the basal diet. After the feeding trials, all treatments were exposed to a non-lethal concentration of AgNPs (0.5 mg L^-1) for 96 h. Fish fed dietary turmeric showed a significantly higher weight gain. The body protein content was significantly increased in all feeding groups, while the lipid content showed a significant decrease in the turmeric-treated group. Dietary turmeric improved the concentration of saturated fatty acids (SFA) and monounsaturated fatty acid (MUFA). AgNP exposure led to increases in liver catalase (CAT) activity of carps fed with turmeric and curcumin. The lowest amount of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was obtained in fish fed with nanomicelle curcumin and curcumin diets. The lowest amount of silver accumulation in the liver of carps was found in fish fed with dietary curcumin nanomicelle. This experiment suggests that supplementation of turmeric (50 g kg^-1) or curcumin (1000 mg kg^-1) may play an important role in enhancing growth performances and fatty acid composition of the common carp. Moreover, administration of curcumin nanomicelle in the diet may have a potential ameliorative effect against toxicity of AgNPs.

The Physical Modeling Analysis of Fate and Transport of Silver Nanoparticles Dispersed by Water Flow

The release of silver nanoparticles (AgNPs) from consumer products into an environment has become a central issue for many countries. Despite that the fate and behaviors of AgNPs incorporated into a wastewater have been investigated by building a model of wastewater treatment process, the transport and retention behaviors of AgNPs influenced by the water flow in a river must be understood. The physical model of simulated river to mimic a natural flow of river was proposed to investigate the behaviors of AgNP transport in the river. The results showed that the large amount of AgNPs deposited on the riverbed as Ag sediment with only 1.26% of AgNPs remained in the water flow. The elemental content of Ag freely dispersed across the riverbed increases from the upstream to downstream area of the simulated river. Verification of the spatial distribution of Ag dispersed along the water flow may contribute to a better understanding of the fate and transport of AgNPs in the aquatic environment.

Nano-QTTR development for interspecies aquatic toxicity of silver nanoparticles between daphnia and fish

Limited studies of quantitative toxicity-toxicity relationship (QTTR) modeling have been conducted to predict interspecies toxicity of engineered nanomaterials (ENMs) between aquatic test species. A meta-analysis of 66 publications providing acute toxicity data of silver nanoparticles (AgNPs) to daphnia and fish was performed, and the toxicity data, physicochemical properties, and experimental conditions were collected and curated. Based on Euclidean distance (ED) grouping, a meaningful correlation of logarithmic lethal concentrations between daphnia and fish was derived for bare (R²_bare = 0.47) and coated AgNPs (R²_coated = 0.48) when a distance of 10 was applied. The correlation of coated AgNPs was improved (R²_coated = 0.55) by the inclusion of descriptors of the coating materials. The correlations were further improved by R²_bare = 0.57 and R²_coated = 0.81 after additionally considering particle size only, and by R²_bare = 0.59 and R²_coated = 0.92 after considering particle size and zeta potential simultaneously. The developed ED-based nano-QTTR model demonstrated that inclusion of the coating material descriptors and physicochemical properties improved the goodness-of-fit to predict interspecies aquatic toxicity of AgNPs between daphnia and fish. This study provides insight for future in silico research on QTTR model development in ENM toxicology.

Nuciferine Attenuates Doxorubicin-Induced Cardiotoxicity: An In Vitro and In Vivo Study

Chemotherapeutic drugs are a known factor that impairs the system of life due to their severe side effects. A more worrying fact is that the patients administered with doxorubicin fall under the risk of cardiotoxicity. The evolution of exploring plant-derived compounds is a possible way to combat health issues in therapeutic applications. Hence, this study focuses on the protective effect of plant-based compound nuciferine (NFN) against doxorubicin-induced cardiotoxicity in both in vitro and in vivo models. In this investigation, nuciferine significantly reduces DOX-mediated cardiotoxicity by mitigating reactive oxygen species, thereby preventing DNA fragmentation, regulating apoptosis genes and reducing the caspase 3/7 levels in vitro. Besides, nuciferine has shown significant protection against DOX-induced cardiac impairment and the upregulation of cardiogenic markers in vivo. The DOX-induced oxidative stress can be mitigated via enhancing the endogenous antioxidants, thereby controlling ROS-mediated apoptosis. In virtue of these potential features, nuciferine can be a budding candidate to address therapeutic needs.

Changes of Gene Expression Patterns from Aquatic Organisms Exposed to Metal Nanoparticles

Metal nanoparticles are used in various branches of industry due to their physicochemical properties. However, with intensive use, most of the waste and by-products from industries and household items, and from weathering of products containing nanoparticles, end up in the waters. These pollutants pose a risk to aquatic organisms, one of which is a change in the expression of various genes. Most of the data that focus on metal nanoparticles and their effects on aquatic organisms are about copper and silver nanoparticles, which is due to their popularity in general industry, but information about other nanoparticulate metals can also be found. This review aims to evaluate gene expression patterns in aquatic organisms by metal nanoparticles, specifying details about the transcription changes of singular genes and, if possible, comparing the changes in the expression of the same genes in different organisms. To achieve this goal, available publications tackling this problem are studied and summarized. Nanometals were found to have a modulatory effect on gene expression in different aquatic organisms. Data show both up-regulation and down-regulation of genes. Nano silver, nano copper, and nano zinc show a regulatory effect on genes involved in inflammation and apoptosis, cell cycle regulation and ROS defense as well as in general stress response and have a negative effect on the expression of genes involved in development. Nano gold, nano titanium, nano zinc, and nano iron tend to elevate the transcripts of genes involved in response to ROS, but also pro-apoptotic genes and down-regulate DNA repair-involved genes and anti-apoptotic-involved genes. Nano selenium showed a rare effect that is protective against harmful effects of other nanoparticles, but also induced up-regulation of stress response genes. This review focuses only on the effects of metal nanoparticles on the expression of various genes of aquatic organisms from different taxonomic groups.

Protective effect of eugenol on hepatic inflammation and oxidative stress induced by cadmium in male rats

BACKGROUND

Cadmium is one of the most toxic heavy metals. The prolonged exposure of it can lead to severe alterations and damage in different tissues including blood, liver, kidney and brain. Eugenol, a phenolic compound, is present in various aromatic plants. It acts as a natural antioxidant and anti-inflammatory agent. The aim of this study was to investigate whether the treatment of eugenol is beneficial against the hepatic oxidative stress and inflammation induced by Cd.

METHODS

To study the effect of eugenol in reversal of Cd toxicity, 24 albino rats were equally divided into four different groups: G1 Control (saline), G2 Eugenol (3 mg kg-1), G3 CdCl2 (5 mg kg-1) and G4 CdCl2 + Eugenol (5 mg kg-1 + 3 mg kg-1). All the groups were treated with gavage orally for the period of 21 days. After this treatment period, rats were sacrificed and liver tissues were removed. The hepatic antioxidant status was evaluated by measuring the activities of SOD, Catalase and GST enzymes. The reduced glutathione, lipid peroxidation, protein carbonyl oxidation (PCO) and thiol contents were measured in hepatic tissues. The activities of liver marker enzymes such as ALT, AST, GGT, ALP, TP, albumin, Bilirubin content and LDH were determined to assess the hepatic damage in different groups. Cd induced hepatic inflammation was determined by evaluating the levels of TNF-a, IL-6 and NO.

RESULTS

Oral intoxication of Cd for 21 days significantly elevated the level of hepatic markers including activities of LDH, GGT, ALP, ALT, AST and Bilirubin level. The albumin content, reduced GSH level, and activities of antioxidant enzymes were significantly reduced in Cd treated group. The levels of inflammatory markers were significantly elevated in Cd treated group. The eugenol treatment was very effective and it significantly reversed the Cd induced biochemical alterations almost similar to that of control.

CONCLUSION

The results demonstrated that the eugenol possessed very strong anti-oxidative and anti-inflammatory potential. The co-treatment of eugenol with Cd exhibited protective potential of eugenol against Cd induced toxicity. Eugenol was able to improve the cellular redox system in rats treated with Cd.

Toxicological Profile of Plasmonic Nanoparticles in Zebrafish Model

Plasmonic nanoparticles are increasingly employed in several fields, thanks to their unique, promising properties. In particular, these particles exhibit a surface plasmon resonance combined with outstanding absorption and scattering properties. They are also easy to synthesize and functionalize, making them ideal for nanotechnology applications. However, the physicochemical properties of these nanoparticles can make them potentially toxic, even if their bulk metallic forms are almost inert. In this review, we aim to provide a more comprehensive understanding of the potential adverse effects of plasmonic nanoparticles in zebrafish (Danio rerio) during both development and adulthood, focusing our attention on the most common materials used, i.e., gold and silver.

Synthesis and characterization of palladium nanoparticles by chemical and green methods: A comparative study on hepatic toxicity using zebrafish as an animal model

Nanoparticles synthesized by chemical methods are of a matter of concern, whereas, the green methods are said to be eco-friendly and environmentally safe. In this study, the toxicity of palladium nanoparticles (Pd NPs) synthesized through chemical co-precipitation and green route method using Annona squamosa seed kernels (As-Pd NPs) were evaluated using zebrafish as an animal model. The synthesized nanoparticles (NPs) were characterized using UV-Visible spectroscopy, Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray (EDX), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS) and Zeta potential. Zebrafish (Danio rerio) were exposed to 0.4 ng/L of Pd NPs and As-Pd NPs for 96-h, further oxidative stress parameters and histological changes were evaluated. The superoxide dismutase (SOD), catalase (CAT) activity and the lipid peroxidation (LPO) levels were elevated in the Pd NPs groups. But in the As-Pd NPs group, the SOD activity showed a biphasic nature while the CAT activity gradually declined till the 96-h compared to the control and Pd NPs groups. The LPO levels in the As-Pd NPs groups showed a measurable increase till 72-h and sudden decline at the end of 96-h. Anomalies in the histological changes such as ruptured hepatocytes, sinusoidal congestion, vacuolation and accumulation of erythrocytes were observed in both the NPs treated groups but As-Pd NPs exhibited lesser lesions than the control and Pd NPs groups. However, our present study reveals the possible reliability of the nanoparticles and the mechanism of scavenging activity suggesting that the As-Pd NPs synthesized by green route are less toxic comparing to the chemically synthesized Pd NPs.

Antagonistic effect of different selenium type on green synthesized silver nanoparticle toxicity on Oreochromis niloticus: oxidative stress biomarkers

The current investigation pointed to report the negative impacts of silver nanoparticles [Ag]^NPs that synthesized by leaf extract of Moringa oleifera on oxidative stress biomarkers of Oreochromis niloticus, as well as the role of different Selenium type to antagonistic that toxicity. Fish were exposed to [Ag]^NPs (1.95 and 3.9 ppm) as sublethal concentrations alongside 0.1 ppm of Se bulk and 0.1 ppm biosynthesized [Se]^NPs selenium nanoparticles antagonistic effect for 2 and 4 weeks. Lipid peroxidation (LPO), DNA fragmentation, total antioxidant capacity (TAOC), catalase (CAT), and superoxide dismutase (SOD) were evaluated as oxidative stress biomarkers,. A significant increase (p < 0.05) in LPO and DNA fragmentation and a significant decrease (p < 0.05) in TAOC, CAT, and SOD were found in [Ag]^NPs exposed groups when compared with the control one. Biosynthesized [Se]^NPs and Se bulk showed a positive role in [Ag]^NPs detoxification. Our investigation suggested that [Ag]^NPs showed a toxic effect on oxidative stress biomarkers. However, Se-NP addition gives a good recovery of oxidative biomarkers more than Se bulk in detoxification of [Ag]^NPs.

In vivo evaluation of Nano-palladium toxicity on larval stages and adult of zebrafish (Danio rerio)

The existence and usage of nano-sized palladium (nano-Pd) as catalytic promoters among industries and researchers have been laid a way to explore the release of nano-Pd particles into the aquatic environment, bio-accumulating in living organisms. However, the data on fate and toxicity in response to nano-Pd on aquatic organisms are very limited. Herein, we report the concentration-specific toxicity of nano-Pd in zebrafish (Danio rerio). Nano-Pd was synthesized and characterized by Field Emission Scanning Electron Microscopy (FE-SEM), Dynamic Light Scattering (DLS) and Zeta potential. To determine the in vivo toxicity of nano-Pd, the 96 hpf larvae and the adult zebrafish were treated with two (22 and 0.4 ng/L) environmental relevant concentrations. High doses of nano-Pd influenced the hatching rate, embryo survival, heartbeat and teratological anomalies in the 96 hpf larvae. Reactive oxygen species (ROS) and apoptosis were also influenced by nano-Pd exposure while the acetylcholinesterase (AChE) activity was declined in a dose dependent manner. In long-term exposure (42 days), the adult fish showed erratic movements in swimming pattern inhibiting the AChE activity in both the concentrations of brain and liver. The antioxidant enzyme activity such as superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione reductase (GR) and lipid peroxidation (LPO), showed a significant change (P < 0.05) indicating that oxidative stress was induced by nano-Pd. Similarly, nano-Pd also induced histopathological lesions in gill, liver and brain providing an insight of fate and toxicity of nano-Pd in the aquatic environment. Our study contributes a significant mechanism to understand the toxicity concern of nano-Pd in the aquatic environment.

Toxicity of silver nanoparticles on different tissues in adult Danio rerio

Although silver nanoparticles (AgNP) are among the most studied nanomaterials by virtue of their broad application in many areas, little is known about their overall toxicity to aquatic organisms after their contamination of the water environment. This study aimed to analyze the effect of the exposure (96 h) to different AgNP concentrations on Danio rerio (zebrafish) tissues. AgNP were synthesized and characterized by transmission electron microscopy (TEM), showing spherical AgNP of 30.00 ± 16.80 nm size. The effects of different AgNP concentrations (1, 3, and 5 μg L^-1) on brain, muscle, gill, and liver tissues of zebrafish were investigated. The results show a significant decrease in brain and muscle acetylcholinesterase (AChE) activity. Liver and gill catalase (CAT) activity also decreased significantly. At the highest exposure concentration, muscle AChE was more inhibited (37.3%) than brain AChE (26.4%) and gill CAT was more inhibited (67.4%) than liver CAT (51.2%). D. rerio also showed gill morphological changes such as fusion of secondary lamellae, curvature, dilated marginal channel, and epithelial lifting. This study indicates that gill CAT together with morphological studies are potential biomarkers for AgNP.

Acute toxicity assessment of polyaniline/Ag nanoparticles/graphene oxide quantum dots on Cypridopsis vidua and Artemia salina

Nanotoxicology is argued and considered one of the emerging topics. In this study, polyaniline (PANI)/2-acrylamido-2-methylpropanesulfonic acid (AMPSA) capped silver nanoparticles (NPs)/graphene oxide (GO) quantum dots (QDs) nanocomposite (PANI/Ag (AMPSA)/GO QDs NC) as a nanoadsorbent has a potential for removal of toxic hexavalent chromium (Cr(VI)) ions from water. The acute toxicity of this NC was evaluated on Artemia salina and freshwater Ostracods (Cypridopsis vidua) larvae for 48 h. The measurements were made at 24 and 48 h with 3 repetitions. The 50% effective concentration (EC50) values of the NC were determined after the exposure of these organisms. According to the results of the optical microscope, it was found that both experimental organisms intake the NC. In the toxicity results of Ostracods, the NC had a highly toxic effect only at 250 mg/L after 48 h and the EC50 value was 157.6 ± 6.4 mg/L. For Artemia salina individuals, it was noted that they were less sensitive than the Ostracods and EC50 value was 476 ± 25.1 mg/L after 48 h. These results indicated that PANI/Ag (AMPSA)/GO QDs NC has low toxicity towards both investigated organisms.

Maternal Responses and Adaptive Changes to Environmental Stress via Chronic Nanomaterial Exposure: Differences in Inter and Transgenerational Interclonal Broods of Daphnia magna

There is increasing recognition that environmental nano-biological interactions in model species, and the resulting effects on progeny, are of paramount importance for nanomaterial (NM) risk assessment. In this work, Daphnia magna F0 mothers were exposed to a range of silver and titanium dioxide NMs. The key biological life history traits (survival, growth and reproduction) of the F1 intergenerations, at the first (F1B1), third (F1B3) and fifth (F1B5) broods, were investigated. Furthermore, the F1 germlines of each of the three broods were investigated over 3 more generations (up to 25 days each) in continuous or removed-from NM exposure, to identify how the length of maternal exposure affects the resulting clonal broods. Our results show how daphnids respond to NM-induced stress, and how the maternal effects show trade-offs between growth, reproduction and survivorship. The F1B1 (and following germline) had the shortest F0 maternal exposure times to the NMs, and thus were the most sensitive showing reduced size and reproductive output. The F1B3 generation had a sub-chronic maternal exposure, whereas the F1B5 generation suffered chronic maternal exposure where (in most cases) the most compensatory adaptive effects were displayed in response to the prolonged NM exposure, including enhanced neonate output and reduced gene expression. Transgenerational responses of multiple germlines showed a direct link with maternal exposure time to 'sub-lethal' effect concentrations of NMs (identified from standard OECDs acute toxicity tests which chronically presented as lethal) including increased survival and production of males in the F1B3 and G1B5 germlines. This information may help to fine-tune environmental risk assessments of NMs and prediction of their impacts on environmental ecology.

Roles of ROS and cell cycle arrest in the genotoxicity induced by gold nanorod core/silver shell nanostructure

To understand the genotoxicity induced in the liver by silver nanoparticles (AgNPs) and silver ions, an engineered gold nanorod core/silver shell nanostructure (Au@Ag NR) and humanized hepatocyte HepaRG cells were used in this study. The involvement of oxidative stress and cell cycle arrest in the DNA and chromosome damage induced by 0.4-20 µg mL^-1 Au@Ag NR were investigated by comet assay, γ-H2AX assay and micronucleus test. Further, the distribution of Au@Ag NR was analyzed. Our results demonstrated that both Ag⁺ and Au@Ag NR led to DNA cleavage and chromosome damage (clastogenicity) in HepaRG cells and that the Au@Ag NR retained in the nucleus may further release Ag⁺, aggravating the damages, which are mainly caused by cell cycle arrest and ROS formation. The results reveal the correlation between the intracellular accumulation, Ag⁺ ion release and the potential genotoxicity of AgNPs.

Combating silver nanoparticle-mediated toxicity in Drosophila melanogaster with curcumin

Nanoscale materials display unique physical and chemical properties that enable their assimilation into a variety of industrial and consumer products. Amongst the widely used nanomaterials, silver nanoparticles (AgNPs) have gained tremendous recognition for various applications, owing to their extraordinary plasmonic and bactericidal properties. Despite of the extensive usage of AgNPs in various sectors, its impact on human health remains ambiguous. Several studies have established that higher doses of AgNPs are detrimental to organismal health. In order to attain the best from these versatile nanoparticles, a recent advent of green nanotechnology, that is, employment of metal nanoparticles synthesized using plant extracts, has emerged. Here, using Drosophila as a model system, we tested if adding curcumin, a biologically active polyphenolic compound present in turmeric, having multitudes of therapeutic properties, could mitigate AgNP-mediated biotoxicity. We found that co-administration of AgNPs with curcumin in the fly food could alleviate several harmful effects evoked by AgNPs ingestion in Drosophila model. Addition of curcumin superseded reduction in feeding, pupation, eclosion, pigmentation, and fertility caused by AgNPs ingestion. Interestingly, impairment in ovary development observed in flies reared on AgNPs-supplemented food was also partially restored by co-administration of AgNPs with curcumin. Furthermore, substantial alleviation of reactive oxygen species level and cell death was observed in larval tissues upon co-supplementation of AgNPs with curcumin. We therefore propose that curcumin, when administered with AgNPs, can abrogate the toxic manifestations of AgNPs ingestion and hence can be incorporated in various consumer products encompassing it.

Toxicity of biosynthesized silver nanoparticles to aquatic organisms of different trophic levels

Although biosynthesized nanoparticles are regarded as green products, research on their toxicity to aquatic food chains is scarce. Herein, biosynthesized silver nanoparticles (Alcea rosea-silver nanoparticles, AR-AgNPs) were produced by the reaction of Ag ions with leaf extract of herbal plant Alcea rosea. Then, the toxic effects of AR-AgNPs and their precursors such as Ag⁺ ions and coating agent (A. rosea leaf extract) on organisms of different trophic levels of a freshwater food chain were investigated. To the three studied aquatic organisms including phytoplankton (Chlorella vulgaris), zooplankton (Daphnia magna) and fish (Danio rerio), the coating agents of AR-AgNPs showed no toxic effects, and Ag⁺ ions were more toxic in comparison to AR-AgNPs. Further investigations revealed that the release of Ag⁺ ions from AR-AgNPs to the test media were not considerable due to the high stability of AR-AgNPs, thus the toxicity stemmed mainly from the particles of AR-AgNPs in all the three trophic levels. Based on values of 72-h EC₅₀ for C. vulgaris, 48-h LC₅₀ for D. magna and 96-h LC₅₀ for D. rerio, the most sensitive organism to AR-AgNPs exposure was D. magna (the second trophic level).

Species-Specific in vitro and in vivo Evaluation of Toxicity of Silver Nanoparticles Stabilized with Gum Arabic Protein

Introduction

We report, herein, in vitro, and in vivo toxicity evaluation of silver nanoparticles stabilized with gum arabic protein (AgNP-GP) in Daphnia similis, Danio rerio embryos and in Sprague Dawley rats.

Purpose

The objective of this investigation was to evaluate in vitro and in vivo toxicity of silver nanoparticles stabilized with gum arabic protein (AgNP-GP), in multispecies due to the recognition that toxicity evaluations beyond a single species reflect the environmental realism. In the present study, AgNP-GP was synthesized through the reduction of silver salt using the tri-alanine-phosphine peptide (commonly referred to as “Katti Peptide”) and stabilized using gum arabic protein.

Methods

In vitro cytotoxicity tests were performed according to ISO 10993–5 protocols to assess cytotoxicity index (IC₅₀) values. Acute ecotoxicity (EC₅₀) studies were performed using Daphnia similis, according to the ABNT NBR 15088 protocols. In vivo toxicity also included evaluation of acute embryotoxicity using Danio rerio (zebrafish) embryos following the OECD No. 236 guidelines. We also used Sprague Dawley rats to assess the toxicity of AgNP-GP in doses from 2.5 to 10.0 mg kg⁻¹ body weight.

Results

AgNP-GP nanoparticles were characterized through UV (405 nm), core size (20±5 nm through TEM), hydrodynamic size (70–80 nm), Zeta (ζ) potential (- 26 mV) using DLS and Powder X ray diffraction (PXRD) and EDS. PXRD showed pattern consistent with the Ag (1 1 1) peak. EC₅₀ in Daphnia similis was 4.40 (3.59–5.40) μg L⁻¹. In the zebrafish species, LC₅₀ was 177 μg L⁻¹. Oral administration of AgNP-GP in Sprague Dawley rats for a period of 28 days revealed no adverse effects in doses of up to 10.0 mg kg⁻¹ b.w. in both male and female animals.

Conclusion

The non-toxicity of AgNP-GP in rats offers a myriad of applications of AgNP-GP in health and hygiene for use as antibiotics, antimicrobial and antifungal agents.

Developmental toxicity of chlorpropham induces pathological changes and vascular irregularities in zebrafish embryos

Chlorpropham is used to prevent sprouting in stored agricultural products. It functions through mitosis inhibition or microtubule assembly inhibition in target organisms including plants, protozoa, and fungi. Although the toxicity ranges of chlorpropham in different organisms are known, specific studies on the environmental contamination and the harmful effects of chlorpropham has not been elucidated. In the present study, we demonstrated that toxicity assays of chlorpropham using zebrafish embryos showed pathological morphology alteration with half the embryos undergoing embryonic death. Fluorescent dye was used in live embryos to identify whether oxidative stress and apoptosis mediated developmental malformation. Specific genes related to apoptosis, ccnd1, ccne1, and cdk6, belonging to cell cycle regulation were downregulated on exposure to sublethal concentrations of chlorpropham. Moreover, vascular morphogenesis, which contributes to the cardiovascular circulatory system, was disrupted by chlorpropham along with decreased expression of specific regulators (flt1, kdr, and vegfaa). These data suggest that environmentally preserved chlorpropham is a potential pollutant in non-target species, especially in aquatic organisms, and emphasizes the need for caution regarding the ecotoxicity of chlorpropham.

Exposure to Oxadiazon-Butachlor causes cardiac toxicity in zebrafish embryos

Oxadiazon-Butachlor (OB) is a widely used herbicide for controlling most annual weeds in rice fields. However, its potential toxicity in aquatic organisms has not been evaluated so far. We used the zebrafish embryo model to assess the toxicity of OB, and found that it affected early cardiac development and caused extensive cardiac damage. Mechanistically, OB significantly increased oxidative stress in the embryos by inhibiting antioxidant enzymes that resulted in excessive production of reactive oxygen species (ROS), eventually leading to cardiomyocyte apoptosis. In addition, OB also inhibited the WNT signaling pathway and downregulated its target genes includinglef1, axin2 and β-catenin. Reactivation of this pathway by the Wnt activator BML-284 and the antioxidant astaxanthin rescued the embryos form the cardiotoxic effects of OB, indicating that oxidative stress, and inhibition of WNT target genes are the mechanistic basis of OB-induced damage in zebrafish. Our study shows that OB exposure causes cardiotoxicity in zebrafish embryos and may be potentially toxic to other aquatic life and even humans.

Effects of wound dressings containing silver on skin and immune cells

Wound dressings with silver have been shown to be cytotoxic in vitro. However, the extrapolation of this cytotoxicity to clinical settings is unclear. We applied dressings with various forms of silver on porcine skin ex vivo and investigated silver penetration and DNA damage. We assessed antimicrobial efficacy, cytotoxicity to skin cells, and immune response induced by the dressings. All dressings elevated the DNA damage marker γ-H₂AX and the expression of stress-related genes in explanted skin relative to control. This corresponded with the amount of silver in the skin. The dressings reduced viability, induced oxidative stress and DNA damage in skin cells, and induced the production of pro-inflammatory IL-6 by monocytes. The oxidative burst and viability of activated neutrophils decreased. The amount of silver released into the culture medium varied among the dressings and correlated with in vitro toxicity. However, antimicrobial efficiencies did not correlate strongly with the amount of silver released from the dressings. Antimicrobial efficiency and toxicity are driven by the form of silver and the construction of dressings and not only by the silver concentration. The damaging effects of silver dressings in ex vivo skin highlight the importance of thorough in vivo investigation of silver dressing toxicity.

Metallic nanoparticle production and exposure/deposition system for toxicological research applications using zebrafish

Metallic nanoparticles (NPs) have been accepted for various applications ranging from cosmetics to medicine. However, no method has been established in the scientific community that is capable of analyzing various metals, sizes, and levels of exposures without the concern of background chemical contaminations. We present here a system utilizing soft-landing ion mobility (SLIM) exposures of laser ablated metallic clusters capable of operating pressures of reduced vacuum (1 Torr) up to ambient (760 Torr) in the presence of a buffer gas. Clusters experience kinetic energies of less than 1 eV upon exiting the SLIM, allowing for the exposure of NPs to take place in a passive manner. While there is no mass-selection of cluster sizes in this work, it does show for the first time the creation and soft-landing of nanoclusters at ambient pressures. Factors such as area coverage and percentage distribution were studied, as well as the different effects that varying surfaces may cause in the agglomeration of the clusters. Furthermore, the system was successfully used to study the effects of silver nanoparticle exposure and determine the specific organs the NPs accumulate in using zebrafish (Danio rerio) as a model organism. This method provides a novel way to synthesize NPs and expose biological organisms for various toxicological analysis.

Progressive impairment of learning and memory in adult zebrafish treated by Al2O3 nanoparticles when in embryos

Al₂O₃ Nanoparticles (Al₂O₃-NPs) have been widely used because of their unique physical and chemical properties, and Al₂O₃-NPs can be released into the environment directly or indirectly. Our previous research found that 13 nm Al₂O₃-NPs can induce neural cell death and autophagy in primarily cultured neural cells in vitro. The aim of this study was to determine where Al₂O₃-NPs at 13 nm particle size can cause neural cells in vivo and assess related behavioural changes and involved potential mechanisms. Zebrafish from embryo to adult were selected as animal models. Learning and memory as functional indicators of neural cells in zebrafish were measured during the development from embryo to adult. Our results indicate that Al₂O₃-NPs treatment in zebrafish embryos stages can cause the accumulation of aluminium content in zebrafish brain tissue, leading to progressive impaired neurodevelopmental behaviours and latent learning and memory performance. Additionally, oxidative stress and disruption of dopaminergic transmission in zebrafish brain tissues are correlated with the dose-dependent and age-dependent accumulation of aluminium content. Moreover, the number of neural cells in the telencephalon tissue treated with Al₂O₃-NPs significantly declined, and the ultramicroscopic morphology indicated profound autophagy alternations. The results suggest that Al₂O₃-NPs has dose-dependent and time-dependent progressive damage on learning and memory performance in adult zebrafish when treated in embryos. This is the first study of the effects of Al₂O₃-NPs on learning and memory during the development of zebrafish from embryo to adult.

Chronic exposure to copper oxide nanoparticles causes muscle toxicity in adult zebrafish

Repeated deposition of copper oxide nanoparticles (CuO-NPs) into aquatic systems makes them a global threat since the NPs accumulate in various organs of the fish particularly skeletal muscle. In the present study, adult zebrafish were exposed to different concentrations of CuO-NPs (1 and 3 mg/L) for a period of 30 days. The status of functional markers (acetylcholinesterase, creatine kinase-MB, and lactate dehydrogenase) and oxidative stress markers (oxidants and antioxidants) were analyzed. The histological changes in muscle were studied followed by the immunohistochemistry expression for catalase. Further, the expression of myoD, myogenin, pax7, β-actin, and desmin was examined by semi-quantitative reverse transcriptase polymerase chain reaction. The results indicated that chronic exposure to CuO-NPs causes muscular damage as evidenced by elevated levels of functional markers. There was a significant increase in the oxidants with reduction in the antioxidant levels, implying that the antioxidant enzymes were unable to scavenge the free radicals induced by the CuO-NPs. The histopathological analysis showed degeneration and atrophy in the treated groups confirming muscle damage. The immunohistochemical catalase expression in the muscle was reduced in the treated groups further supporting the evidence that the antioxidant has suffered a decline. The altered gene expression indicates skeletal muscle damage due to the CuO-NPs exposure. Overall, the data suggest that chronic exposure to CuO-NPs caused muscular toxicity which may lead to muscle degeneration in adult zebrafish.

Effects of nanosilver on hematologic, histologic and molecular parameters of rainbow trout (Oncorhynchus mykiss)

Efficient antibacterial and antifungal properties of silver nanoparticles (AgNPs) sparked its commercial application in several industrial and household products. Drastic increase of AgNPs production raised concerns over aquatic organisms' exposure. The toxic dose, mechanism of toxicity, physiological damages, gene expression alteration, hematological and blood parameter distortion by AgNP needs to be investigated to explore inevitable risk in aquatic animals. In this study, rainbow trout (Oncorhynchus mykiss) (122.4 ± 1.4 g, 23.8 ± 0.7 cm) were exposed to colloidal AgNPs (28.3 ± 12.6 um) to determine the lethal concentration (LC50)(8.9 mg/l). Sub-lethal concentrations (10 %LC50, 25 %LC50, plus LC50 value) impact on hematologic, histological and molecular responses were evaluated. Results showed sever damage to blood cells morphology, and hematologic parameters change including RBC, WBC, Hct and Hb in all AgNP-treated groups. Histological damage in gill and liver of exposed fish were observed. Significant up-regulating of HSP70 and P53 genes were detected in response to AgNPs, whereas, it was found that in comparison to HSP70 gene, P53 induction occurred in lower AgNPs concentrations and lower exposure time. These results indicate adversely effects of AgNPs exposure to aquatic environments.

Silver nanoparticles (AgNPs) and AgNO3 perturb the specification of human hepatocyte-like cells and cardiomyocytes

Silver nanoparticles (AgNPs) are commonly utilized industrial compounds mostly because of their antimicrobial properties. Nevertheless, our understanding of their potential developmental toxicity in humans is still limited. Embryonic stem cells (ESCs) are powerful in vitro tools for developmental toxicity assessments of chemicals. Here, we evaluated the potential developmental toxicity during early embryogenesis of AgNPs and AgNO₃ with human ESC (hESC)-based differentiation systems in vitro. We found that human relevant concentrations of AgNPs and Ag ions affected the specification of two of the three primary germ layers, endoderm and mesoderm, without drastically affecting ectoderm. Furthermore, the two forms of Ag impaired the generation and functions of hepatocytes-like cells derived from endoderm, by decreasing the expression of important liver markers such as AFP, ALB, and HNF4A, and altering glycogen storage. When considering cardiac development, AgNPs and AgNO₃ manifested opposite adverse effects, in that AgNPs increased while AgNO₃ decreased the expression of typical cardiac markers (NKX2.5, MYH6, and ISL) in hESC-derived cardiomyocytes. In conclusion, our findings argue for a potential developmental toxicity of AgNP doses we are exposed to, or levels detected in the human body, especially at very early stages during embryogenesis, and which may not be just due to Ag leakage. Moreover, mesendoderm-derived cell types, tissues and organs may be more prone to AgNP toxicity than ectoderm lineages.

Coexposed nanoparticulate Ag alleviates the acute toxicity induced by ionic Ag+in vivo

Health concerns of silver nanoparticles (AgNPs) emerged with the increase of their industrial and biomedical application and thus human exposure. The highly dynamic properties of AgNPs lead to coexposure to nanoparticulate and ionic silver, and the combined effects of different Ag species might alter their individual toxicity. Herein, the toxicity of AgNPs combined with ionic Ag⁺ toward the rat was investigated after intravenous (i.v.) exposure to either AgNPs (5 mg/kg), Ag⁺ (5 mg/kg), or a mixture of Ag⁺ and AgNPs (5 mg/kg for both). Comparable results by histopathological and biochemical studies revealed that the exposure to individual AgNPs causes no apparent toxicity in rats, while Ag⁺ ions at the same dose induced marked acute toxicity. More importantly, while there was a negligible combined effect on the Ag accumulation, the less toxic AgNPs ameliorated Ag⁺ induced toxicity to rat organs after coexposure to the mixture of Ag⁺ and AgNPs, which might result from the complexation of Ag⁺ with the thiols like metallothioneins. Therefore, the combined toxicity of particulate and ionic Ag was complicated by their individual toxicities and also their interaction with intracellular detoxification biomolecules, regardless of differences in Ag accumulation. Although further investigations are still needed for the potential toxic mechanisms of the coexposed AgNPs and Ag⁺, considerations of the combined toxicity of different Ag species will reflect more accurate assessments of their health impacts.

Acute toxicity of gold nanoparticles synthesized from macroalga Saccharina japonica towards Daphnia magna

This study was performed to explore acute toxicity of biologically synthesized gold nanoparticles (AuNPs) to a model organism Daphnia magna. Hence, using aqueous extract of marine macroalga Saccharina japonica, two AuNPs including SJ-AuNPs-72 (72.6 ± 43.8 nm) and SJ-AuNPs-10 (10.8 ± 2.8 nm) were synthesized. These AuNPs were characterized by different techniques such as UV-Vis spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDX). The 48-h LC₅₀ values of SJ-AuNPs-72 and SJ-AuNPs-10 to D. magna were 1.57 ± 0.07 and 2.69 ± 0.12 mg/L, respectively, showing greater toxicity of SJ-AuNPs-72. After exposure of daphnids to treatments, AuNPs were accumulated in gut tract, and lipid droplets under the Daphnia carapace were also observed. Whereas studies on toxicity of biosynthesized AuNPs are still scarce, the achievements of this work are helpful for understanding the toxicity of biosynthesized AuNPs to crustacean D. magna.

Multigenerational Exposures of Daphnia Magna to Pristine and Aged Silver Nanoparticles: Epigenetic Changes and Phenotypical Ageing Related Effects

Engineered nanoparticles (NPs) undergo physical, chemical, and biological transformation after environmental release, resulting in different properties of the "aged" versus "pristine" forms. While many studies have investigated the ecotoxicological effects of silver (Ag) NPs, the majority focus on "pristine" Ag NPs in simple exposure media, rather than investigating realistic environmental exposure scenarios with transformed NPs. Here, the effects of "pristine" and "aged" Ag NPs are systematically evaluated with different surface coatings on Daphnia magna over four generations, comparing continuous exposure versus parental only exposure to assess recovery potential for three generations. Biological endpoints including survival, growth and reproduction and genetic effects associated with Ag NP exposure are investigated. Parental exposure to "pristine" Ag NPs has an inhibitory effect on reproduction, inducing expression of antioxidant stress related genes and reducing survival. Pristine Ag NPs also induce morphological changes including tail losses and lipid accumulation associated with aging phenotypes in the heart, abdomen, and abdominal claw. These effects are epigenetic remaining two generations post-maternal exposure (F2 and F3). Exposure to identical Ag NPs (same concentrations) aged for 6 months in environmentally realistic water containing natural organic matter shows considerably reduced toxicological effects in continuously exposed generations and to the recovery generations.

The effects of silver nanoparticles (Ag-NPs) sublethal concentrations on common carp (Cyprinus carpio): Bioaccumulation, hematology, serum biochemistry and immunology, antioxidant enzymes, and skin mucosal responses

The present study aimed to evaluate the effects of different waterborne sublethal concentrations of Ag-NPs LC₅₀ (96h) on common carp Cyprinus carpio using a multi-biomarker approach. Fish (9.22 ± 0.12 g) were stocked in fiberglass tanks and exposed to concentrations of 0 (control), 12.5%, 25% and 50% of Ag-NPs LC₅₀ (96h) or Ag-NO₃ LC₅₀ (96h), as the source of Ag⁺ ion, for a period of 21 days. At the end of study, tissue Ag contents were significantly (P < 0.05) higher and different in fish exposed to concentrations of 25% and 50% compared to the control. The numbers of RBCs, hematocrit, and MCHC values at these concentrations differed significantly in respect to the control. No significant effects were observed for hemoglobin, MCH, and MCV values. The number of WBCs was significantly higher at concentrations of 12.5% and 25% compared to the control. Meanwhile, the percentage of neutrophils significantly elevated at concentrations of 25% and 50%. Serum total protein at concentration of 50% detected significantly lower than that of 12.5% or the control. The serum albumin and globulin levels significantly declined in Ag-NPs-exposed groups versus the control. The serum ACH50 and total immunoglobulins showed significantly lower values in the treatments of 25% and 50% compared to the control. The serum glucose, cortisol, ALT, and ALP values significantly escalated upon Ag-NPs exposure. The serum SOD and CAT showed enhanced activity in the treatment of 12.5% vice versa significantly diminished at concentrations of 25% and 50% compared to the control. The exposure to the concentrations of 25% and 50% significantly dwindled the lysozyme activity and total immunoglobulin levels in skin mucus. In conclusion, sublethal concentrations of Ag-NPs LC₅₀ (96h) impaired fish health status at higher concentrations and 12.5% of Ag-NPs LC₅₀ (96h) was presumably safe for common carp aquaculture.

Nanosized-Ag-doped porous β-tricalcium phosphate for biological applications

The treatment of infectious or potentially infective bone defects remains a major problem in clinical practice. Silver has the ability to potentiate antibiotics against resistant bacterial strains. In order to reduce the risk of long-term infections, it is necessary for the biomaterial scaffold to release Ag⁺ in a controlled manner during the entire healing process. In this study, given the antimicrobial characteristics of nanosized Ag (NSAg), we synthesized β-tricalcium phosphate (β-TCP) doped with 5 and 10 wt% NSAg (5 wt% NSAgTCP and 10 wt% NSAgTCP, respectively). The NSAgTCP composites exhibited similar macroporous structures to pure β-TCP. The NSAgTCP samples were examined by scanning electron microscopy at 10,000-times magnification, which revealed that silver was still present at the nanometer scale. X-ray diffraction revealed that silver does not change the crystalline properties of β-TCP. In addition, we observed that the mechanical strength of NSAgTCP increased with increasing amounts of added Ag. The antibacterial, physical, and chemical properties of NSAgTCP were investigated in vitro. We found that NSAgTCP is effective at inhibiting the growth of Staphylococcus aureus and Escherichia coli and is not cytotoxic to human bone marrow mesenchymal stem cells. Moreover, it does not hinder liver or kidney function when tested in vivo. As the bioceramic degrades, Ag ions are slowly released and new bone is formed. No significant cytotoxic effects were observed even when 10 wt% NSAgTCP was used. NSAgTCP has the ability to simultaneously repair bone defects and act as an anti-infective agent; hence, we expect that this material, with its good bone-repairing and anti-infective properties, will find wide spread use as a novel bone substitute.

Toxicological impact of green synthesized silver nanoparticles and protective role of different selenium type on Oreochromis niloticus: hematological and biochemical response

BACKGROUND

The present work aimed to detect the toxicological effects of green synthesized silver nanoparticles (Ag-NPs) by using Moringa Oleifera leaves extract on hematological and biochemical parameters of Oreochromis niloticus.

METHODS

Adult fish were exposed to two sublethal concentrations (1.95 and 3.9 ppm) of Ag-NPs against sodium selenite (0.1 ppm) and biosynthesized selenium nanoparticles (Se-NPs); 0.1 ppm; protection role for 2 and 4 weeks. Hematological parameters; erythrocyte count (RBCs), hemoglobin content (Hb), haematocrit value (Hct), mean corpuscular volume (MCV), Mean Corpuscular Hemoglobin Concentration (MCHC), leucocytes (WBCs), with differential count Micronucleus (MN) and alerted cells and biochemical parameters; aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) enzyme activities, serum protein (total protein, albumin and globulin) concentration, urea, creatinine, glucose, cholesterol (Cho) and triglyceride (Tg) were detected.

RESULTS

The present investigation showed that Ag-NPs in different doses led to a significant reduction (p < 0.05) in RBCs, Hb, Hct, MCV, WBCs, LYM and serum proteins concentration. However, MCHC, MN, alerted cells, NEUT, AST, ALT, ALP enzyme activities, urea, creatinine, glucose, Cho and Tg showed a significant increases (p < 0.05) when compared with control group. Sodium selenite (Se) and biosynthesized selenium nanoparticles (Se-NPs) play an optimistic role in detoxification of Ag-NPs toxicity.

CONCLUSION

The results suggest the negative impact of Ag-NPs on hematology and biochemical parameters of fish. Moreover, Se-NPs showed a full improvement of hematological and biochemical parameters more than that of sodium selenite in elimination of Ag-NPs toxicity.

Silver Nanoparticles in Zebrafish (Danio rerio) Embryos: Uptake, Growth and Molecular Responses

Silver nanoparticles (AgNPs) are widely used in commercial applications as antimicrobial agents, but there have recently been increasing concerns raised about their possible environmental and health impacts. In this study, zebrafish embryos were exposed to two sizes of AgNP, 4 and 10 nm, through a continuous exposure from 4 to 96 h post-fertilisation (hpf), to study their uptake, impact and molecular defense responses. Results showed that zebrafish embryos were significantly impacted by 72 hpf when continuously exposed to 4 nm AgNPs. At concentrations above 0.963 mg/L, significant in vivo uptake and delayed yolk sac absorption was evident; at 1.925 mg/L, significantly reduced body length was recorded compared to control embryos. Additionally, 4 nm AgNP treatment at the same concentration resulted in significantly upregulated hypoxia inducible factor 4 (HIF4) and peroxisomal membrane protein 2 (Pxmp2) mRNA expression in exposed embryos 96 hpf. In contrast, no significant differences in terms of larvae body length, yolk sac absorption or gene expression levels were observed following exposure to 10 nm AgNPs. These results demonstrated that S4 AgNPs are available for uptake, inducing developmental (measured as body length and yolk sac area) and transcriptional (specifically HIF4 and Pxmp2) perturbations in developing embryos. This study suggests the importance of particle size as one possible factor in determining the developmental toxicity of AgNPs in fish embryos.

TiO2 nanoparticles and multi-walled carbon nanotubes monitoring and bioremediation potential using ciliates Pseudocohnilembus persalinus

In recent years, the release of nanomaterials pollutants to water bodies, to a great extent, attributed to anthropogenic activities. Their impacts on aquatic organisms as well as nanomaterial monitoring and bioremediation using organism have drawn much attentions. However, studies on relationship of nano-contaminants and aquatic organisms are very scarce. Our results showed that titanium dioxide nanoparticles (TiO₂-NPs) and Multi-walled carbon nanotubes (MWCNTs) caused an obvious cell decreases on the whole, but a significant increase at 48 h TiO₂-NPs exposure, indicating a resistant mechanism in ciliates for nano-toxic. Besides, MWCNTs was more toxic to Pseudocohnilembus persalinus than that of TiO₂-NPs in terms of EC₅₀ value. It is firstly found that P. persalinus ingested and released TiO₂-NPs through cytostome and cytoproct, which might be the reason that TiO₂-NPs less toxic than MWCNTs. The significantly increased superoxide dismutase (SOD) and glutathione S-transferase (GST) enzyme activities and expression levels were evaluated by reactive oxygen species ROS generation, which demonstrated that P. persalinus antioxidant defense enzyme played roles on nano-toxic resistant in ciliates. Moreover, the integrated biomarker response (IBR) was also determined, which demonstrated that MWCNTs had comparatively higher values than those of TiO₂-NPs after higher concentration exposure to ciliates. In addition, it was confirmed by the present work that sod, gst and cat played different roles on immunity, and the sensitivity of cat gene expression to these two nanomaterials exposure was dissimilar. Damages of shrunk as well as losses of cilia on the cell surface caused by TiO₂-NPs and MWCNTs exposure in P. persalinus using SEM revealed possible physical hazards of aggregated nanomaterials. Our findings will be helpful to understand the effect mechanisms of NPs on ciliates, and also demonstrated the possibility of P. persalinus as bio-indicator of nanomaterials in aquatic and potentials on bioremediation.

The toxicity of non-aged and aged coated silver nanoparticles to the freshwater shrimp Paratya australiensis

Nanoparticles (NPs) transform in the environment which result in alterations to their physicochemical properties. However, the effects of aging on the toxicity of NPs to aquatic organisms remain to be determined. Further the reports that have been published present contradictory results. The aim of this study was to examine the stability of differently coated silver nanoparticles (AgNPs) in media and the influence of aging of these NP on potential toxicity to freshwater shrimp Paratya australiensis. Coating-dependent changes in the stability of AgNP were observed with aging. Curcumin (C) coated AgNPs were stable, while tyrosine (T) coated AgNPs and epigallocatechin gallate (E) coated AgNPs aggregated in the P. australiensis medium. Increased lipid peroxidation and catalase activity was noted in P. australiensis exposed to AgNPs, suggesting oxidative stress was associated with NP exposure. The enhanced oxidative stress initiated by aged C-AgNPs suggests that aging of these NPs produced different toxicological responses. In summary, data suggest that coating-dependent alterations in NPs, together with aging affect both persistence and subsequent toxicity of NPs to freshwater organisms. Thus, the coating-dependent fate and toxicity of AgNPs together with the effect of their aging need to be considered in assessing the environmental risk of AgNPs to aquatic organisms.