How toxic is a non-toxic nanomaterial: Behaviour as an indicator of effect in Danio rerio exposed to nanogold

Tributyltin exposure disrupted the locomotor activity rhythms in adult zebrafish (Danio rerio) and the mechanism involved

The fish circadian rhythm system might be an emerging target of tributyltin (TBT), however, the mechanism by which TBT interferes with the circadian rhythm is poorly understood. Therefore, in the present study, zebrafish were used to assess the effects of TBT at environmental concentrations (1 and 10 ng/L) on locomotor activity rhythm. Furthermore, we focused on the visual system to explore the potential mechanism involved. After 90 d of exposure, TBT disturbed the locomotor activity rhythms in zebrafish, which manifested as: (1) low activities and lethargy during the arousing period; (2) inability to fall asleep quickly and peacefully during the period of latency to sleep; and (3) no regular "waves" of locomotor activities during the active period. After TBT exposure, the histological structure of the eyes significantly changed, the boundary between layers became blurred, and the melanin concentrations significantly decreased. Using KEGG and GSEA pathway analyses, the differentially expressed genes in the eyes screened by transcriptomics were significantly enriched in the tyrosine metabolism pathway and retinol metabolism pathway. Furthermore, a decrease in melanin and disruption of retinoic acid were found after TBT exposure, which would affect the reception of phototransduction, and then interfere with the circadian rhythm in fish. The disruption of the circadian rhythm of fish by aquatic pollutants would decrease their ecological adaptability, which should be considered in future research.

Lethal effects and ultrastructure of cellular uptake of ingested gold nanoparticles in the freshwater rotifer Brachionus calyciflorus (Monogononta: Brachionidae)

Much of the recent literature concerning the threat posed by anthropogenic microscopic pollution has focussed on marine organisms although freshwater environments face the same degree of pollution and therefore risk. Although several studies have documented the ingestion of nanoparticles (NPs) in species of the pelagic freshwater rotifer genus Brachionus, unambiguous evidence for its cellular uptake in this group remains lacking. We therefore used transmission electron microscopy (TEM) of ultrathin sections through the digestive tract of individuals of Brachionus calyciflorus exposed in vitro to citrate stabilized gold nanoparticles (AuCit NPs) in their culture medium to provide the first concrete evidence for the cellular uptake of NPs in rotifers, a group of organisms that comprise an important part of the zooplankton community. Using this method, AuCit NPs with average diameters of 8.5 ± 1.4 nm and 12.5 ± 1.5 nm could be localized clearly within large vacuoles within the stomach cells. Moreover, the occasional presence of pits containing AuCit NPs in the outer membranes of these cells hints that the particles are taken up by some form of endocytosis. In all cases, the ingestion of AuCit NPs showed lethal effects after only one day with virtually no individuals surviving more than two days of exposure. Combined with the TEM evidence above, we hypothesize that death might derive from some form of lysosomal overload. In total, our results document the potential threat that microscopic pollution also poses for freshwater organisms. Through this, we hope that additional emphasis in this context will be directed toward freshwater environments and the potential for such pollution both to enter as well as to move up the food chain via trophic transfer events.

Green Metallic Nanoparticles for Cancer Therapy: Evaluation Models and Cancer Applications

Metal-based nanoparticles are widely used to deliver bioactive molecules and drugs to improve cancer therapy. Several research works have highlighted the synthesis of gold and silver nanoparticles by green chemistry, using biological entities to minimize the use of solvents and control their physicochemical and biological properties. Recent advances in evaluating the anticancer effect of green biogenic Au and Ag nanoparticles are mainly focused on the use of conventional 2D cell culture and in vivo murine models that allow determination of the half-maximal inhibitory concentration, a critical parameter to move forward clinical trials. However, the interaction between nanoparticles and the tumor microenvironment is not yet fully understood. Therefore, it is necessary to develop more human-like evaluation models or to improve the existing ones for a better understanding of the molecular bases of cancer. This review provides recent advances in biosynthesized Au and Ag nanoparticles for seven of the most common and relevant cancers and their biological assessment. In addition, it provides a general idea of the in silico, in vitro, ex vivo, and in vivo models used for the anticancer evaluation of green biogenic metal-based nanoparticles.

A review of the effects of metallic nanoparticles on fish

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

Effects of conventionally-treated and ozonated wastewater on mortality, physiology, body length, and behavior of embryonic and larval zebrafish (Danio rerio)

To date, micropollutants from anthropogenic sources cannot be completely removed from effluents of wastewater treatment plants and therefore enter freshwater systems, where they may impose adverse effects on aquatic organisms, for example, on fish. Advanced treatment such as ozonation aims to reduce micropollutants in wastewater effluents and, thus, to mitigate adverse effects on the environment. To investigate the impact and efficiency of ozonation, four different water types were tested: ozonated wastewater (before and after biological treatment), conventionally-treated wastewater, and water from a river (River Ruhr, Germany) upstream of the wastewater treatment plant effluent. Zebrafish (Danio rerio) embryos were used to study lethal and sublethal effects in a modified fish early life-stage test. Mortality occurred during exposure in the water samples from the wastewater treatment plant and the river in the first 24 h post-fertilization, ranging from 12% (conventional wastewater) to 40% (river water). Regarding sublethal endpoints, effects compared to the negative control resulted in significantly higher heart rates (ozonated wastewater), and significantly reduced swimming activity (highly significant in ozonated wastewater and ozone reactor water, significant in only the last time interval in river water). Moreover, the respiration rates were highly increased in both ozonated wastewater samples in comparison to the negative control. Significant differences between the ozonated wastewater samples occurred in the embryonic behavior and heart rates, emphasizing the importance of subsequent biological treatment of the ozonated wastewater. Only the conventionally-treated wastewater sample did not elicit negative responses in zebrafish, indicating that the discharge of conventional wastewater poses no greater risk to embryonic and larval zebrafish than water from the river Ruhr itself. The sublethal endpoints embryonic- and larval behavior, heart rates, and respiration were found to be the most sensitive endpoints in this fish early life-stage test and can add valuable information on the toxicity of environmental samples.

Gold Nanoparticles; Potential Nanotheranostic Agent in Breast Cancer: A Comprehensive Review with Systematic Search Strategy

BACKGROUND

Breast cancer is a heterogeneous disease typically prevalent among women and is the second-largest cause of death worldwide. Early diagnosis is the key to minimize the cancer-induced complication, however, the conventional diagnostic strategies have been sluggish, complex, and, to some extent, non-specific. Therapeutic tools are not so convenient and side effects of current therapies offer the development of novel theranostic tool to combat this deadly disease.

OBJECTIVE

This article aims to summarize the advances in the diagnosis and treatment of breast cancer with gold nanoparticles (GNP or AuNP).

METHODS

A systematic search was conducted in the three popular electronic online databases including PubMed, Google Scholar, and Web of Science, regarding GNP as breast cancer theranostics.

RESULTS

Published literature demonstrated that GNPs tuned with photosensitive moieties, nanomaterials, drugs, peptides, nucleotide, peptides, antibodies, aptamer, and other biomolecules improve the conventional diagnostic and therapeutic strategies of breast cancer management with minimum cytotoxic effect. GNP derived diagnosis system assures reproducibility, reliability, and accuracy cost-effectively. Additionally, surface-modified GNP displayed theranostic potential even in the metastatic stage of breast cancer.

CONCLUSION

Divergent strategies have shown the theranostic potential of surface tuned GNPs against breast cancer even in the metastatic stage with minimum cytotoxic effects both in vitro and in vivo.

Toxicity in vitro and in Zebrafish Embryonic Development of Gold Nanoparticles Biosynthesized Using Cystoseira Macroalgae Extracts

INTRODUCTION

Research on gold nanoparticles (AuNPs) occupies a prominent place in the field of biomedicine nowadays, being their putative toxicity and bioactivity areas of major concern. The green synthesis of metallic nanoparticles using extracts from marine organisms allows the avoidance of hazardous production steps while maintaining features of interest, thus enabling the exploitation of their promising bioactivity.

OBJECTIVE

To synthesize and characterize AuNPs using, for the first time, macroalga Cystoseira tamariscifolia aqueous extract (Au@CT).

METHODS

Algal aqueous extracts were used for the synthesis of AuNPs, which were characterized using a wide panel of physicochemical techniques and biological assays.

RESULTS

The characterization by UV-Vis spectroscopy, transmission electron microscopy, Z-potential and infrared spectroscopy confirmed that Au@CT were stable, spherical and polycrystalline, with a mean diameter of 7.6 ± 2.2 nm. The antioxidant capacity of the extract, prior to and after synthesis, was analyzed in vitro, showing that the high antioxidant potential was not lost during the synthesis. Subsequently, in vitro and in vivo toxicity was screened, by comparing two species of the genus Cystoseira (C. tamariscifolia and C. baccata) and the corresponding biosynthesized gold nanoparticles (Au@CT and Au@CB). Cytotoxicity was tested in mouse (L929) and human (BJ5ta) fibroblast cell lines. In both cases, only the highest (nominal) test concentration of both extracts (31.25 mg/mL) or Au@CB (12.5 mM) significantly affected cell viability, as measured by the MTT assay. These results were corroborated by a Fish Embryo Acute Toxicity (FET) test. Briefly, it was shown that, at the highest (nominal) tested concentration (31.25 mg/mL), CT extract induced significantly higher cytotoxicity and embryotoxicity than CB extract. However, it was demonstrated that Au@CT, but not Au@CB, were generally non-toxic. At sub-lethal (nominal) test concentrations (1.25 and 2.5 mM), Au@CT affected zebrafish embryonic development to a much lesser extent than Au@CB. In vitro wound healing assays also revealed that, while other experimental conditions did not impact cell migration, CT and Au@CT displayed a moderate positive effect.

CONCLUSION

Au@CT and Au@CB display promising features, desirable for biomedical applications, as wound healing.

Boron Oxide Nanoparticles Exhibit Minor, Species-Specific Acute Toxicity to North-Temperate and Amazonian Freshwater Fishes

Boron oxide nanoparticles (nB₂O₃) are manufactured for structural, propellant, and clinical applications and also form spontaneously through the degradation of bulk boron compounds. Bulk boron is not toxic to vertebrates but the distinctive properties of its nanostructured equivalent may alter its biocompatibility. Few studies have addressed this possibility, thus our goal was to gain an initial understanding of the potential acute toxicity of nB₂O₃ to freshwater fish and we used a variety of model systems to achieve this. Bioactivity was investigated in rainbow trout (Oncorhynchus mykiss) hepatocytes and at the whole animal level in three other North and South American fish species using indicators of aerobic metabolism, behavior, oxidative stress, neurotoxicity, and ionoregulation. nB₂O₃ reduced O. mykiss hepatocyte oxygen consumption (ṀO₂) by 35% at high doses but whole animal ṀO₂ was not affected in any species. Spontaneous activity was assessed using ṀO₂ frequency distribution plots from live fish. nB₂O₃ increased the frequency of high ṀO₂ events in the Amazonian fish Paracheirodon axelrodi, suggesting exposure enhanced spontaneous aerobic activity. ṀO₂ frequency distributions were not affected in the other species examined. Liver lactate accumulation and significant changes in cardiac acetylcholinesterase and gill Na⁺/K⁺-ATPase activity were noted in the north-temperate Fundulus diaphanus exposed to nB₂O₃, but not in the Amazonian Apistogramma agassizii or P. axelrodi. nB₂O₃ did not induce oxidative stress in any of the species studied. Overall, nB₂O₃ exhibited modest, species-specific bioactivity but only at doses exceeding predicted environmental relevance. Chronic, low dose exposure studies are required for confirmation, but our data suggest that, like bulk boron, nB₂O₃ is relatively non-toxic to aquatic vertebrates and thus represents a promising formulation for further development.

OSBPL2 Is Required for the Binding of COPB1 to ATGL and the Regulation of Lipid Droplet Lipolysis

The accumulation of giant lipid droplets (LDs) increases the risk of metabolic disorders including obesity and insulin resistance. The lipolysis process involves the activation and transfer of lipase, but the molecular mechanism is not completely understood. The translocation of ATGL, a critical lipolysis lipase, from the ER to the LD surface is mediated by an energy catabolism complex. Oxysterol-binding protein-like 2 (OSBPL2/ORP2) is one of the lipid transfer proteins that regulates intracellular cholesterol homeostasis. A recent study has proven that Osbpl2^−/− pigs exhibit hypercholesterolemia and obesity phenotypes with an increase in adipocytes. In this study, we identified that OSBPL2 links the endoplasmic reticulum (ER) with LDs, binds to COPB1, and mediates ATGL transport. We provide important insights into the function of OSBPL2, indicating that it is required for the regulation of lipid droplet lipolysis.

•

LD lipolysis is impaired in OSBPL2/osbpl2b-mutant HepG2 cells and zebrafish

•

OSBPL2 interacts with COPB1, a subunit of the COPI complex located on LDs

•

Altered COPI complexes on LDs may perturb the trafficking of lipolysis lipase ATGL

Common mechanisms activated in the tissues of aquatic and terrestrial animal models after TiO2 nanoparticles exposure

Titanium dioxide nanoparticles (TiO₂-NPs) are among the most popular manufactured and widely used nanoparticles. They are released into the environment, affecting terrestrial and aquatic ecosystems, with unexpected consequences to organisms and human health. The present study investigates the mediated toxicity imposed to the freshwater fish species, zebrafish (Danio rerio) and the prussian carp (Carassius gibelio), and to the terrestrial land snail Cornu aspersum, after their exposure to sublethal concentrations of TiO₂-NPs. Oxidative, proteolytic, genotoxic and apoptotic parameters in fish liver and gills, as well as on snail hemocytes were studied and the swimming performance was estimated in order to (a) estimate and suggest the most susceptible animal, and (b) propose a common battery of biomarkers as the most suitable indicator for biomonitoring studies against TiO₂-NPs. Our in vivo experiments demonstrated that NPs induced detrimental effects on animal physiology and swimming behavior, while no general pattern was observed in species and tissues responsiveness. Generally, TiO₂-NPs seemed to activate a group of molecules that are common for aquatic as well as terrestrial animals, implying the existence of a conserved mechanism. It seems that after exposure to TiO₂-NPs, a common mechanism is activated that involves the stimulation of immune system with the production of ROS, damage of lysosomal membrane, protein carbonylation, lipid peroxidation, DNA damage, following proteolysis by ubiquitin and finally apoptosis. Thus, the simultaneous use of the latter biomarkers could be suggested as a reliable multi parameter approach for biomonitoring of aquatic and terrestrial ecosystems against TiO₂-NPs.

Differential Cytotoxicity Induced by Transition Metal Oxide Nanoparticles is a Function of Cell Killing and Suppression of Cell Proliferation

The application of nanoparticles (NPs) in industry is on the rise, along with the potential for human exposure. While the toxicity of microscale equivalents has been studied, nanoscale materials exhibit different properties and bodily uptake, which limits the prediction ability of microscale models. Here, we examine the cytotoxicity of seven transition metal oxide NPs in the fourth period of the periodic table of the chemical elements. We hypothesized that NP-mediated cytotoxicity is a function of cell killing and suppression of cell proliferation. To test our hypothesis, transition metal oxide NPs were tested in a human lung cancer cell model (A549). Cells were exposed to a series of concentrations of TiO₂, Cr₂O₃, Mn₂O₃, Fe₂O₃, NiO, CuO, or ZnO for either 24 or 48 h. All NPs aside from Cr₂O₃ and Fe₂O₃ showed a time- and dose-dependent decrease in viability. All NPs significantly inhibited cellular proliferation. The trend of cytotoxicity was in parallel with that of proliferative inhibition. Toxicity was ranked according to severity of cellular responses, revealing a strong correlation between viability, proliferation, and apoptosis. Cell cycle alteration was observed in the most toxic NPs, which may have contributed to promoting apoptosis and suppressing cell division rate. Collectively, our data support the hypothesis that cell killing and cell proliferative inhibition are essential independent variables in NP-mediated cytotoxicity.