Ecological risk assessment of silicon dioxide nanoparticles in a freshwater fish Labeo rohita: Hematology, ionoregulation and gill Na(+)/K(+) ATPase activity

Mechanistic Insights into Toxicity of Titanium Dioxide Nanoparticles at the Micro- and Macro-levels

Titanium oxide nanoparticles (TiO2 NPs) have been regarded as a legacy nanomaterial due to their widespread usage across multiple fields. The TiO2 NPs have been and are still extensively used as a food and cosmetic additive and in wastewater and sewage treatment, paints, and industrial catalysis as ultrafine TiO2. Recent developments in nanotechnology have catapulted it into a potent antibacterial and anticancer agent due to its excellent photocatalytic potential that generates substantial amounts of highly reactive oxygen radicals. The method of production, surface modifications, and especially size impact its toxicity in biological systems. The anatase form of TiO2 (<30 nm) has been found to exert better and more potent cytotoxicity in bacteria as well as cancer cells than other forms. However, owing to the very small size, anatase particles are able to penetrate deep tissue easily; hence, they have also been implicated in inflammatory reactions and even as a potent oncogenic substance. Additionally, TiO2 NPs have been investigated to assess their toxicity to large-scale ecosystems owing to their excellent reactive oxygen species (ROS)-generating potential compounded with widespread usage over decades. This review discusses in detail the mechanisms by which TiO2 NPs induce toxic effects on microorganisms, including bacteria and fungi, as well as in cancer cells. It also attempts to shed light on how and why it is so prevalent in our lives and by what mechanisms it could potentially affect the environment on a larger scale.

From lab to ecosystem: Understanding the ecological footprints of engineered nanoparticles

Nanotechnology has attained significant attention from researchers in past decades due to its numerous advantages, such as biocompatibility, biodegradability, and improved stability over conventional drug delivery systems. The fabrication of engineered nanoparticles (ENPs), including carbon nanotubes (CNTs), fullerenes, metallic and metal oxide-based NPs, has been steadily increasing day due to their wide range of applications from household to industrial applications. Fabricated ENPs can release different materials into the environment during their fabrication process. The effect of such materials on the environment is the primary concern with due diligence on the safety and efficacy of prepared NPs. In addition, an understanding of chemistry, reactivity, fabrication process, and viable mechanism of NPs involved in the interaction with the environment is very important. To date, only a limited number of techniques are available to assess ENPs in the natural environment which makes it difficult to ascertain the impact of ENPs in natural settings. This review extensively examines the environmental effects of ENPs and briefly discusses useful tools for determining NP size, surface charge, surface area, and external appearance. In conclusion, the review highlights the potential risks associated with ENPs and suggests possible solutions.

Prospects and hazards of silica nanoparticles: Biological impacts and implicated mechanisms

With the thrive of nanotechnology, silica nanoparticles (SiNPs) have been extensively adopted in the agriculture, food, cosmetic, and even biomedical industries. Due to the mass production and use, SiNPs inevitably entered the environment, resulting in ecological toxicity and even posing a threat to human health. Although considerable investigations have been conducted to assess the toxicity of SiNPs, the correlation between SiNPs exposure and consequent health risks remains ambiguous. Since the biological impacts of SiNPs can differ from their design and application, the toxicity assessment for SiNPs may be extremely difficult. This review discussed the application of SiNPs in different fields, especially their biomedical use, and documented their potential release pathways into the environment. Meanwhile, the current process of assessing SiNPs-related toxicity on various model organisms and cell lines was also detailed, thus estimating the health threats posed by SiNPs exposure. Finally, the potential toxic mechanisms of SiNPs were also elaborated based on results obtained from both in vivo and in vitro trials. This review generally summarizes the biological effects of SiNPs, which will build up a comprehensive perspective of the application and toxicity of SiNPs.

Nanosilica and copper ecotoxicity in Gambusia holbrooki fish

When silica nanoparticles (SiNP) reach the water bodies interact with the already existing pollutants in the environments. This study aimed to evaluate the ecotoxicity of SiNP under the presence/absence of Cu in mosquitofish (Gambusia holbrooki). Fish were exposed to 0, 10 and 100 mg SiNP L-1, alone or mixed with Cu (0.25 mg L-1). After 96 h, the amount of colony forming units (CFU) of bacteria living on the skin mucus was analysed, and oxidative stress, tissue damage enzymes, and neurotoxicity were evaluated. We observed a reduction in CFU when Cu was present in the media. The liver was the target organ, evidencing a decrease in tissue damage enzymatic activities, activation of the antioxidant system in all treatments, and lipid oxidative damage when the SiNP and Cu were mixed. Overall, SiNP ecotoxicity was proved, which could also be enhanced by the presence of ubiquitous elements such as metals.

Synthesis and Characterization of Silica, Silver-Silica, and Zinc Oxide-Silica Nanoparticles for Evaluation of Blood Biochemistry, Oxidative Stress, and Hepatotoxicity in Albino Rats

Evaluation of nanoparticles (NPs) for biomedical applications has received a lot of attention for detailed study on pharmacokinetics prior to clinical application. In this study, pure C-SiO₂ (crystalline silica) NPs and SiO₂ nanocomposites with silver (Ag) and zinc oxide (ZnO) were prepared by utilizing different synthesis routes such as sol-gel and co-precipitation techniques. The prepared NPs showed highly crystalline nature as confirmed by X-ray diffraction analysis where average crystallite sizes of 35, 16, and 57 nm for C-SiO₂, Ag-SiO₂, and ZnO-SiO₂ NPs, respectively, were calculated. Fourier transform infrared analysis confirmed the presence of functional groups related to the chemicals and procedures used for sample preparation. Due to agglomeration of the prepared NPs, the scanning electron microscope images showed large particle sizes when compared to their crystalline sizes. The optical properties of the prepared NPs such as absorption were obtained with UV-Vis spectroscopy. For in vivo biological evaluation, albino rats, both male and female, kept in different groups were exposed to NPs with 500 μg/kg dose. Hematological, serum biochemistry, histo-architecture, oxidative stress biomarkers, and antioxidant parameters in liver tissues along with various biomarkers for the evaluation of erythrocytes were estimated. The results on hemato-biochemistry, histopathological ailments, and oxidative stress parameters exhibited 95% alteration in the liver and erythrocytes of C-SiO₂ NPs-treated rats while 75 and 60% alteration in the liver tissues of rats due to exposure to Ag-SiO₂ and ZnO-SiO₂ NPs, respectively, when compared with the albino rats of the control (untreated) group. Therefore, the current study showed that the prepared NPs had adverse effects on the liver and erythrocytes causing hepatotoxicity in the albino rats in respective order C-SiO₂ > Ag SiO₂ > ZnO-SiO₂. As the C-SiO₂ NPs appeared to be the most toxic, it has been concluded that coating SiO₂ on Ag and ZnO reduced their toxicological impact on albino rats. Consequently, it is suggested that Ag-SiO₂ and ZnO-SiO₂ NPs are more biocompatible than C-SiO₂ NPs.

Individual and binary exposure to nanoscales of silver, titanium dioxide, and silicon dioxide alters viability, growth, and reproductive system: Hidden indices to re-establish artemia as a toxicological model in saline waters

This study evaluated and compared the individual and combined toxicity of AgNPs, TiO₂NPs, and SiO₂NPs to life cycle of A. salina. To this end, both stability and toxicity of AgNPs were determined in the presence of TiO₂NPs and SiO₂NPs. The colloidal stability of AgNPs decreased in the presence of the other two NPs, especially SiO₂NPs. AgNPs displayed acute toxicity to A. salina, whereas SiO₂NPs and TiO₂NPs chronically induced toxicity in a concentration- and time-dependent manner during 28-day exposure. The experimental NPs significantly decreased the weight and length of A. salina and induced reproductive toxicity through perturbation in first brood timespan, sexual maturity, egg development time, egg pouch area, offspring quality, and fecundity. Exposure to AgNPs shifted the mode of reproduction in brine shrimp from ovoviviparity to oviparity, and also co-presence of AgNPs with SiO₂NPs or TiO₂NPs caused infertility. Generally, their individual toxicity was in order of AgNPs > TiO₂NPs > SiO₂NPs, and binary exposure to AgNPs-SiO₂NPs appear to be more threatening than AgNPs-TiO₂NPs to A. salina. Together, this study highlights that these nanoparticles could disrupt reproductive health of A. salina and lead to alterations in population dynamics and aquatic ecosystem balance.

Investigation of the Biosafety of Antibacterial Mg(OH)2 Nanoparticles to a Normal Biological System

The toxicity of Mg(OH)₂ nanoparticles (NPs) as antibacterial agents to a normal biological system is unclear, so it is necessary to evaluate their potential toxic effect for safe use. In this work, the administration of these antibacterial agents did not induce pulmonary interstitial fibrosis as no significant effect on the proliferation of HELF cells was observed in vitro. Additionally, Mg(OH)₂ NPs caused no inhibition of the proliferation of PC-12 cells, indicating that the brain's nervous system was not affected by Mg(OH)₂ NPs. The acute oral toxicity test showed that the Mg(OH)₂ NPs at 10,000 mg/kg induced no mortality during the administration period, and there was little toxicity in vital organs according to a histological analysis. In addition, the in vivo acute eye irritation test results showed little acute irritation of the eye caused by Mg(OH)₂ NPs. Thus, Mg(OH)₂ NPs exhibited great biosafety to a normal biological system, which was critical for human health and environmental protection.

Changes in energy reserves and responses of some biomarkers in freshwater mussels exposed to metal-oxide nanoparticles

In this study, responses of various biomarkers in the digestive gland and foot muscle of freshwater mussels (Unio tigridis) were investigated following exposure to Al₂O₃, CuO and TiO₂ nanoparticles (NPs) for 14 days at different concentrations (0, 1, 3 and 9 mg NP/L). Mussels were fed on unicellular algae (Chlorella vulgaris) cultured in the laboratory. NP exposures caused significant increases (p < 0.05) in the levels of total glutathione (GSH), reduced-glutathione (rGSH), oxidized-glutathione (GSSG) and malondialdehyde (MDA) in the digestive gland. Oppositely, there were significant (p < 0.05) decreases in acetylcholinesterase activity in the foot muscles. Total energy reserves of the digestive gland and foot muscle significantly (p < 0.05) decreased, but only at the highest NP exposures. Nevertheless, NP exposures did not alter (p > 0.05) the algae filtering capacity of mussels. This study demonstrated that the biomarkers belonging to different metabolic systems responded to NP exposures, suggesting their usage in the monitoring studies for freshwater systems.

Nano-ecotoxicology in a changing ocean

The ocean faces an era of change, driven in large by the release of anthropogenic CO2, and the unprecedented entry of pollutants into the water column. Nanomaterials, those particles < 100 nm, represent an emerging contaminant of environmental concern. Research on the ecotoxicology and fate of nanomaterials in the natural environment has increased substantially in recent years. However, commonly such research does not consider the wider environmental changes that are occurring in the ocean, i.e., ocean warming and acidification, and occurrence of co-contaminants. In this review, the current literature available on the combined impacts of nanomaterial exposure and (i) ocean warming, (ii) ocean acidification, (iii) co-contaminant stress, upon marine biota is explored. Here, it is identified that largely co-stressors influence nanomaterial ecotoxicity by altering their fate and behaviour in the water column, thus altering their bioavailability to marine organisms. By acting in this way, such stressors, are able to mitigate or elevate toxic effects of nanomaterials in a material-specific manner. However, current evidence is limited to a relatively small set of test materials and model organisms. Indeed, data is biased towards effects upon marine bivalve species. In future, expanding studies to involve other ecologically significant taxonomic groups, primarily marine phytoplankton will be highly beneficial. Although limited in number, the available evidence highlights the importance of considering co-occurring environmental changes in ecotoxicological research, as it is likely in the natural environment, the material of interest will not be the sole stressor encountered by biota. As such, research examining ecotoxicology alongside co-occurring environmental stressors is essential to effectively evaluating risk and develop effective long-term management strategies.

Salinity and/or nanoparticles (Al2O3, TiO2) affect metal accumulation and ATPase activity in freshwater fish (Oreochromis niloticus)

The osmoregulation system of freshwater fish is sensitive to salinity increase in water. There is no satisfactory data to our knowledge on the accumulation of metal-oxide nanoparticles (NPs) in tissues of O. niloticus and their effects on ATPases (Na,K-ATPase, Mg-ATPase, Ca-ATPase) in differing salinities. Thus, this study investigated the effects of salinity (0 and 10 ppt) and Al₂O₃ and TiO₂ NPs (1 and 10 mg NPs/L) on the response of ATPases in acute (2 days) and chronic (20 days) durations. Data showed that nanoparticles accumulated in the tissues of fish, gill tissues having the highest levels of Al and Ti in both acute and chronic durations. Interestingly, the higher salinity significantly increased (P < 0.05) NP accumulations in the tissues in acute exposures, whereas it significantly decreased (P < 0.05) in chronic exposures. Salinity increase caused significant decreases (P < 0.05) in ATPase activities (up to 54 %) in control fish from both exposure protocols. Likewise, NP alone exposures (up to 80 %) and salt+NP (up to 83 %) exposures generally caused significant (P < 0.05) decreases in ATPase activities compared to their controls. Similarly, salt+NP exposures also decreased ATPase activities compared to NP exposures alone. The present data demonstrated that salinity and/or NP exposures decreased ATPase activities in the gill of freshwater fish, emphasizing the possible hazardous consequences of salt inputs and NP discharges into freshwater systems.

Improvement of synaptic plasticity by nanoparticles and the related mechanisms: Applications and prospects

Synaptic plasticity is an important basis of learning and memory and participates in brain network remodelling after different types of brain injury (such as that caused by neurodegenerative diseases, cerebral ischaemic injury, posttraumatic stress disorder (PTSD), and psychiatric disorders). Therefore, improving synaptic plasticity is particularly important for the treatment of nervous system-related diseases. With the rapid development of nanotechnology, increasing evidence has shown that nanoparticles (NPs) can cross the blood-brain barrier (BBB) in different ways, directly or indirectly act on nerve cells, regulate synaptic plasticity, and ultimately improve nerve function. Therefore, to better elucidate the effect of NPs on synaptic plasticity, we review evidence showing that NPs can improve synaptic plasticity by regulating different influencing factors, such as neurotransmitters, receptors, presynaptic membrane proteins and postsynaptic membrane proteins, and further discuss the possible mechanism by which NPs improve synaptic plasticity. We conclude that NPs can improve synaptic plasticity and restore the function of damaged nerves by inhibiting neuroinflammation and oxidative stress, inducing autophagy, and regulating ion channels on the cell membrane. By reviewing the mechanism by which NPs regulate synaptic plasticity and the applications of NPs for the treatment of neurological diseases, we also propose directions for future research in this field and provide an important reference for follow-up research.

Aquatic ecotoxicity of manufactured silica nanoparticles: A systematic review and meta-analysis

Manufactured silica nanoparticles are used worldwide in large volumes for a variety of applications. An exposure of environmental organisms is therefore likely, and several data on the ecotoxicology of silica nanoparticles to different organisms have been published in recent years. This systematic review compiles and assesses these studies, in order to analyse the sensitivity distribution across different organisms. On this basis, maximum acceptable environmental concentrations are suggested and potential environmental risks are discussed. 1429 papers were retrieved from the scientific literature (Scopus), the U.S. ECOTOX knowledge database. 63 studies were finally included in the review and appraised according to the nanoCRED criteria. A total of 219 ecotoxicological endpoints recorded in 38 species (7 taxonomic groups) were condensed into a species sensitivity distribution. The resulting concentration that is hazardous for a maximum of 5% of exposed species (HC05) is 130 μg/L, from which a PNEC of 30 μg/L is estimated by applying an assessment factor of 5. These concentrations are 1-3 orders of magnitudes above the concentrations modelled to occur in European aquatic ecosystems. Algae and bacteria have a comparatively low sensitivity to MSNP exposure, likely because their cell wall forms a protective barrier against nanoparticle exposure. Similarly, embryonic stages of fish also show a comparatively low sensitivity due to the protection from their chorion. However, the fish species Labeo rohita and Oncorhynchus mykiss are among the most sensitive species. The ecotoxicity of silica nanoparticles is linked to the number of hydroxyl groups on their surface, corresponding to findings from human toxicological studies. It is recommended that future ecotoxicological studies use explicit concentration-response designs, use proven biocide-free testing material, comparatively apply mass and surface area as exposure metrics, and provide important metainformation in the study report.

Effect of environmental factors on hematology profile of Gambusia affinis caught at Brantas River watershed, Indonesia

Background: Contamination of freshwater ecosystems has become a major issue as it threatens public water sources as well as aquatic life. It is important to predict changes in organism health, given a known number of environmental factors and pollutant concentrations, in order to better manage contaminants through biomarker analysis. This study aims to examine the ecosystem health of the Brantas River based on its environmental condition and the hematology profile of Gambusia affinis fish present in the river. This species was chosen because of its wide distribution along the Brantas River, and because it is very tolerant, adaptable, highly abundant, and easy to catch. Methods: The study area included 10 sampling sites along the Brantas River watershed. In total, six water quality parameters were observed (temperature, pH, dissolved oxygen (DO), biological oxygen demand (BOD), ammonia concentration, and phenol concentration) and hematology measurements consisted of erythrocyte, leucocyte, and micronuclei analyses. Results: The results showed that the upstream area of Brantas River, located in Batu, was the least polluted region, while Mojokerto was the most polluted. The erythrocyte level of Gambusia affinis caught in most sampling sites was quite low. Furthermore, research revealed that the status of Gambusia affinis' hematological profile was significantly correlated (p<0.05) with water quality parameters, particularly DO, BOD, ammonia, and phenol. Conclusions: It can be concluded from these results that the hematological profile of the fish is poor due to high levels of organic waste and harmful substances.

Effect of environmental factors on blood counts of Gambusia affinis caught at Brantas River watershed, Indonesia

Background: Contamination of freshwater ecosystems has become a major issue as it threatens public water sources as well as aquatic life. It is important to predict changes in organism health, given a known number of environmental factors and pollutant concentrations, in order to better manage contaminants through biomarker analysis. This study aims to examine the ecosystem health of the Brantas River based on its environmental condition and the hematology profile of Gambusia affinis fish present in the river. This species was chosen because of its wide distribution along the Brantas River, and because it is very tolerant, adaptable, highly abundant, and easy to catch. Methods: The study area included 10 sampling sites along the Brantas River watershed. In total, six water quality parameters were observed (temperature, pH, dissolved oxygen (DO), biological oxygen demand (BOD), ammonia concentration, and phenol concentration) and hematology measurements consisted of erythrocyte, leucocyte, and micronuclei analyses. Results: The results showed that the upstream area of Brantas River, located in Batu, was the least polluted region, while Mojokerto was the most polluted. The erythrocyte level of Gambusia affinis caught in most sampling sites was quite low. Furthermore, research revealed that the status of Gambusia affinis' hematological profile was significantly correlated (p<0.05) with water quality parameters, particularly DO, BOD, ammonia, and phenol. Conclusions: It can be concluded from these results that the hematological profile of the fish is poor due to high levels of organic waste and harmful substances.

Metallic, metal oxide, and metalloid nanoparticles toxic effects on freshwater microcrustaceans: An update and basis for the use of new test species

In this article, we performed a literature review on the metallic, metal oxide, and metalloid nanoparticles (NP) effects on freshwater microcrustaceans, specifically focusing on (i) the main factors influencing the NP toxicity and (ii) their main ecotoxicological effects. Also, given that most studies are currently developed on the standard test species Daphnia magna Straus, we analyzed (iii) the potential differences in the biological responses between D. magna and other freshwater microcrustacean, and (iv) the ecological implications of considering only D. magna as surrogate of other microcrustaceans. We found that NP effects on microcrustaceans depended on their intrinsic properties as well as the exposure conditions. Among the general responses to different NP, we identified body burial, feeding inhibition, biochemical effects, metabolic changes, and reproductive and behavioral alterations. The differences in the biological responses between D. magna and other freshwater microcrustacean rely on the morphology (size and shape), ecological traits (feeding mechanisms, life cycles), and intrinsic sensitivities. Thus, we strongly recommend the use of microcrustaceans species with different morphological, physiological, and ecological characteristics in future ecotoxicity tests with NP to provide relevant information with regulation purposes regarding the discharge of NP into aquatic environments. PRACTITIONER POINTS: Nanoparticles effects depend on intrinsic and external factors. Nanoparticles affect the morphology, physiology, and behavior. Effects on Daphnia differ from other microcrustaceans. The use of more diverse test species is suggested.

Ecotoxicity of silica nanoparticles in aquatic organisms: An updated review

This review aims to (i) provide a current overview of the main characteristics of SiNP (physical and chemical properties, applications, and emissions), (ii) evaluate the scientific production up to date concerning SiNP, with focus on their toxic effects, through a bibliometric analysis, (iii) describe the main toxic mechanisms of SiNP, (iv) assess the current knowledge about ecotoxicity of SiNP on aquatic organisms (marine and freshwater), and (v) identify the main gaps in the knowledge of SiNP toxicity from an environmentally point of view. The scientific production of SiNP concerning their chemical and physical characteristics has increased exponentially. However, little information is available regarding their ecotoxicity. Particle functionalization is a key factor that reduces SiNP toxicity. Most of the studies employed standard species as test organisms, being the local/native ones poorly represented. Further studies employing long-term exposures and environmentally relevant concentrations are needed to deepen the knowledge about this emergent pollutant.

Does the Site of Blood Collection in Fish Affect Haematological and Blood Biochemical Results?

The values of haematological and selected blood plasma biochemical parameters of juvenile common carp (Cyprinus carpio Linnaeus, 1758) were compared between blood samples taken from caudal vein and heart to evaluate the influence of blood sampling body site on the obtained results in two groups of fish of different blood sampling order: I – first by caudal and then by cardiac puncture, II – first by cardiac and then by caudal puncture. The obtained results revealed statistically significant (p<0.05) differences only in group I where red blood cell (RBC) count was higher in caudal vein blood, while haematocrit (Ht) value, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), total protein (TP) concentration, and magnesium (Mg) level were higher in cardiac blood samples. No statistically significant differences occurred in white blood cell (WBC) count, differential leukocyte count or erythrocyte morphology based on stained blood smears. The obtained results showed that blood sampling body site may affect the results of haematological and plasma biochemical analyses.

Multiple Roles of Mesoporous Silica in Safe Pesticide Application by Nanotechnology: A Review

Pollution related to pesticides has become a global problem due to their low utilization and non-targeting application, and nanotechnology has shown great potential in promoting sustainable agriculture. Nowadays, mesoporous silica-based nanomaterials have garnered immense attention for improving the efficacy and safety of pesticides due to their distinctive advantages of low toxicity, high thermal and chemical stability, and particularly size tunability and versatile functionality. Based on the introduction of the structure and synthesis of different types of mesoporous silica nanoparticles (MSNs), the multiple roles of mesoporous silica in safe pesticide application using nanotechnology are discussed in this Review: (i) as nanocarrier for sustained/controlled delivery of pesticides, (ii) as adsorbent for enrichment or removal of pesticides in aqueous media, (iii) as support of catalysts for degradation of pesticide contaminants, and (iv) as support of sensors for detection of pesticides. Several scientific issues, strategies, and mechanisms regarding the application of MSNs in the pesticide field are presented, with their future directions discussed in terms of their environmental risk assessment, in-depth mechanism exploration, and cost-benefit consideration for their continuous development. This Review will provide critical information to related researchers and may open up their minds to develop new advances in pesticide application.

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

Simple Summary

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

Abstract

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

Effects of SiO2 nanoparticles on the uptake of tetrabromobisphenol A and its impact on the thyroid endocrine system in zebrafish larvae

The coexistence of nanoparticles and organic toxicants in the environment modifies pollutant bioavailability and toxicity. This study investigated the influence of silicon dioxide nanoparticles (n-SiO₂) on the uptake of tetrabromobisphenol A (TBBPA) and its impact on the thyroid endocrine system in zebrafish larvae. Zebrafish (Danio rerio) embryos were exposed to TBBPA at different concentrations (50, 100, and 200 μg/L) alone or in combination with n-SiO₂ (25 mg/L) until 120 h post-fertilization (hpf). Chemical measurements showed that both TBBPA and n-SiO₂ were bioconcentrated in zebrafish larvae, and the uptake of TBBPA was enhanced by n-SiO₂. Furthermore, zebrafish larvae exposed to 200 μg/L TBBPA alone exhibited significantly increased T4 contents and decreased T3 contents, whereas n-SiO₂ treatment alone did not have a detectable effect. Furthermore, the thyroid hormone levels changed more upon treatment with 200 μg/L TBBPA combined with 25 mg/L n-SiO₂ than upon TBBPA treatment alone. Alterations in gene transcription along the related hypothalamic-pituitary-thyroid (HPT) axis were observed, and expression of the binding and transport protein transthyretin (TTR) was significantly decreased for both TBBPA alone and co-exposure with n-SiO₂. Thus, the current study demonstrates that n-SiO₂, even at the nontoxic concentrations, increases thyroid hormone disruption in zebrafish larvae co-exposed to TBBPA by promoting its bioaccumulation and bioavailability.

Monobutyl phthalate (MBP) induces energy metabolism disturbances in the gills of adult zebrafish (Danio rerio)

Monobutyl phthalate (MBP) is a primary metabolite of an environmental endocrine disruptor dibutyl phthalate (DBP), which poses a potential threat to living organisms. In this research, the acute toxicity of MBP on energy metabolism in zebrafish gills was studied. Transmission electron microscopy (TEM) results show that 10 mg L^-1 MBP can induce mitochondrial structural damage of chloride cells after 96 h of continuous exposure. The activity of ion ATPase and the expression level of oxidative phosphorylation-related genes suggest that MBP interferes with ATP synthesis and ion transport. Further leading to a decrease in mitochondrial membrane potential (MMP) and cell viability, thereby mediating early-stage cell apoptosis. Through a comprehensive analysis of principal component analysis (PCA) and integrated biomarker response (IBR) scores, atp5a1, a subunit of mitochondrial ATP synthase, is mainly inhibited by MBP, followed by genes encoding ion ATPase (atp1b2 and atp2b1). Importantly, MBP inhibits aerobic metabolism by inhibiting the key enzyme malate dehydrogenase (MDH) in the TCA cycle, forcing zebrafish to maintain ATP supply by enhancing anaerobic metabolism.

Hepatic toxicological responses of SiO2 nanoparticle on Oreochromis mossambicus

The present study was carried out to investigate the impact of various concentrations of SiO₂ nanoparticles (SiO₂ NP) on the commonly available freshwater fish Oreochromis mossambicus. The 96 h median lethal concentration (LC₅₀) of SiO₂ NP was found to be between 270-280 ppm. This novel study has demonstrated histological alterations in the hepatic tissues and a dose-dependent depletion of tissue protein content and an elevated transaminases activity in the treated fish, which has facilitated understanding of the impact of SiO₂ NP in O. mossambicus.

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.

Monobutyl phthalate (MBP) can dysregulate the antioxidant system and induce apoptosis of zebrafish liver

In this paper, the acute toxicity of monobutyl phthalate (MBP), the main hydrolysis product of dibutyl phthalate, on adult zebrafish liver antioxidant system was studied. Compared the toxicity effect of MBP and DBP by histopathology and apoptosis experiments, we speculated that the toxic effects of DBP on animals may be caused by its metabolite MBP. The results indicated that the antioxidant Nrf2-Keap1 pathway was insufficient to resist MBP-induced hepatotoxicity and led to an imbalance of membrane ion homeostasis and liver damage. Decreased cell viability, significant tissue lesions and early hepatocyte apoptosis were observed in the zebrafish liver in MBP exposure at high concentration (10 mg/L). The activities of antioxidant enzymes and ATPases in zebrafish liver were inhibited with increased malondialdehyde (MDA) content and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. Integrated biomarker response (IBR) calculation results indicated that MBP mainly inhibited catalase (CAT) activity. Simultaneously, the expression of antioxidant-related genes (SOD, CAT, GPx, Nrf2, HO-1) was down-regulated, while apoptosis-related genes (p53, bax, cas3) were significantly up-regulated.

Interactions of nanomaterials with ion channels and related mechanisms

The pharmacological potential of nanotechnology, especially in drug delivery and bioengineering, has developed rapidly in recent decades. Ion channels, which are easily targeted by external agents, such as nanomaterials (NMs) and synthetic drugs, due to their unique structures, have attracted increasing attention in the fields of nanotechnology and pharmacology for the treatment of ion channel-related diseases. NMs have significant effects on ion channels, and these effects are manifested in many ways, including changes in ion currents, kinetic characteristics and channel distribution. Subsequently, intracellular ion homeostasis, signalling pathways, and intracellular ion stores are affected, leading to the initiation of a range of biological processes. However, the effect of the interactions of NMs with ion channels is an interesting topic that remains obscure. In this review, we have summarized the recent research progress on the direct and indirect interactions between NMs and ion channels and discussed the related molecular mechanisms, which are crucial to the further development of ion channel-related nanotechnological applications.

The fate and oxidative stress of different sized SiO2 nanoparticles in zebrafish (Danio rerio) larvae

Nanoparticle such as silicon dioxide nanoparticles (nano-SiO₂) are extensively produced and applied in society. Hence there is an increasing concern about their exposure and toxicity to human and wildlife. To understand the effects of sizes of NPs on their bioavailability and toxicity, zebrafish (Danio rerio) embryos (2 h post-fertilization, hpf) were exposed to 25, 50 and 100 mg/L of 15 or 30 nm nano-SiO₂ for 5 days respectively. The results showed that SiO₂ could be readily uptaken by zebrafish, and the accumulation of SiO₂ was significantly higher in 15 nm treatments groups compared to 30 nm nano-SiO₂ treated groups. Furthermore, exposure to 15 nm nano-SiO₂ at the concentration of 100 mg/L resulted in more significant changes in reactive oxygen species (ROS) levels, perturbation of lipid peroxidative and antioxidant system than the same concentration of 30 nm nano-SiO₂, indicating small sized nano-SiO₂ evoked severer oxidative stress in zebrafish larvae. In addition, the more significant up-regulation of transcription of genes related to oxidative stress (e.g., nrf2 and sod1) in 15 nm nano-SiO₂ at the 100 mg/L treatments groups provided more evidence for this speculation. Given the above, 15 nm nano-SiO₂ were more likely to enter and accumulate in zebrafish larvae, thus causing more serious oxidative stress in vivo. These results may provide additional information on the fate and toxicities of different sizes of NPs.

Investigation of toxic effects of amorphous SiO2 nanoparticles on motility and oxidative stress markers in rainbow trout sperm cells

In this study, we investigated the effects of SiO₂ nanoparticles (SiO₂-NPs) (1, 10, 25, 50, and 100 mg/L) for 24 h in vitro on the motility parameters and oxidative stress markers such as total glutathione (TGSH), catalase (CAT), and malondialdehyde (MDA) of rainbow trout, Oncorhynchus mykiss sperm cells. Therefore, SiO₂-NPs were synthesized with sol-gel reaction from tetraethoxy orthosilicate (TEOS). The prepared nanoparticle structures were characterized for chemical structure, morphology and thermal behavior employing Fourier transform infrared spectroscopy, X-ray spectroscopy, scanning electron micrograph, and thermal analysis (DTA/TGA/DSC) techniques. After exposure, there was statistically significant (p < 0.05) decreases in velocities of sperm cells. CAT activity significantly (p < 0.05) decreased by 9.6% in sperm cell treated with 100 mg/L. In addition, MDA level significantly increased by 70.4% and 77.5% in sperm cell treated with 50 and 100 mg/L SiO₂-NPs, respectively (p < 0.05). These results showed that SiO₂-NPs may have toxic effect on rainbow trout sperm cells in 50 mg/L and more.

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

Concerns regarding the potential toxic effects of zinc oxide nanoparticles (ZnO NPs) on aquatic organisms are growing due to the fact that NPs may be released into aquatic ecosystems. This study aimed to investigate the effects of dietary exposure to ZnO NPs on juvenile common carp (Cyprinus carpio). Fish were fed a spiked diets at doses 50 and 500mg of ZnO NPs per kg of feed for 6 weeks followed by a 2-week recovery period. Fish were sampled every 2 weeks for haematology trends, blood biochemistry measures, histology analyses, and determination of the accumulation of zinc in tissues. At the end of the exposure and post-exposure periods, fish were sampled for an assessment of lipid peroxidation levels. Dietborne ZnO NPs had no effects on haematology, blood biochemistry, and lipid peroxidation levels during the exposure period. After the recovery period, aspartate aminotransferase activity significantly (p < 0.05) increased and alanine transferase activity significantly (p < 0.05) decreased in the higher exposure group. The level of lipid peroxidation significantly (p < 0.05) decreased in liver of treated fish after 2 weeks post-exposure period. A histological examination revealed mild histopathological changes in kidneys during exposure. Our results did not show a significant increase of zinc content at the end of experiment in any of tested organs. However, chronic dietary exposure to ZnO NPs might affect kidney and liver function.

Environmental dynamics of metal oxide nanoparticles in heterogeneous systems: A review

Metal oxide nanoparticles (MNPs) have been used for many purposes including water treatment, health, cosmetics, electronics, food packaging, and even food products. As their applications continue to expand, concerns have been mounting about the environmental fate and potential health risks of the nanoparticles in the environment. Based on the latest information, this review provides an overview of the factors that affect the fate, transformation and toxicity of MNPs. Emphasis is placed on the effects of various aquatic contaminants under various environmental conditions on the transformation of metal oxides and their transport kinetics - both in homogeneous and heterogeneous systems - and the effects of contaminants on the toxicity of MNPs. The presence of existing contaminants decreases bioavailability through hetero-aggregation, sorption, and/or complexation upon an interaction with MNPs. Contaminants also influence the fate and transport of MNPs and exhibit their synergistic toxic effects that contribute to the extent of the toxicity. This review will help regulators, engineers, and scientists in this field to understand the latest development on MNPs, their interactions with aquatic contaminants as well as the environmental dynamics of their fate and transformation. The knowledge gap and future research needs are also identified, and the challenges in assessing the environmental fate and transport of nanoparticles in heterogeneous systems are discussed.

In vivo effects of Aphanizomenon flos-aquae DC-1 aphantoxins on gas exchange and ion equilibrium in the zebrafish gill

Aphantoxins, neurotoxins or paralytic shellfish poisons (PSPs) generated by Aphanizomenon flos-aquae, are a threat to environmental safety and human health in eutrophic waters worldwide. The molecular mechanisms of neurotoxin function have been studied; however, the effects of these neurotoxins on oxidative stress, ion transport, gas exchange, and branchial ultrastructure in fish gills are not fully understood. Aphantoxins extracted from A. flos-aquae DC-1 were detected by high-performance liquid chromatography. The major ingredients were gonyautoxins 1 and 5 and neosaxitoxin, which comprised 34.04%, 21.28%, and 12.77% of the total, respectively. Zebrafish (Danio rerio) were administered A. flos-aquae DC-1 aphantoxins at 5.3 or 7.61μg saxitoxin equivalents (eq)/kg (low and high doses, respectively) by intraperitoneal injection. The activities of Na(+)-K(+)-ATPase (NKA), carbonic anhydrase (CA), and lactate dehydrogenase (LDH), ultrastructural alterations in chloride and epithelial cells, and reactive oxygen species (ROS) and total antioxidative capacity (T-AOC) were investigated in the gills during the first 24h after exposure. Aphantoxins significantly increased the level of ROS and decreased the T-AOC in zebrafish gills from 3 to 12h post-exposure, suggesting an induction of oxidative stress and inhibition of antioxidant capacity. Reduced activities of NKA and CA demonstrated abnormal ion transport and gas exchange in the gills of aphantoxin-treated fish. Toxin administration also resulted in increased LDH activity and ultrastructural alterations in chloride and epithelial cells, suggesting a disruption of function and structure in zebrafish gills. The observed abnormalities in zebrafish gills occurred in a time- and dose-dependent manner. These findings demonstrate that aphantoxins or PSPs may inhibit ion transport and gas exchange, increase LDH activity, and result in ultrastructural damage to the gills through elevations in oxidative stress and reduced antioxidant capacity. These effects of aphantoxins in the gills of zebrafish suggest an induction of respiratory toxicity. The parameters investigated in this study may be also considered as biomarkers for studying aphantoxin/PSP exposure and cyanobacterial blooms in nature.