Silver Nanoparticle Exposure Research Articles

Global gene expression signatures in response to citrate-coated silver nanoparticles exposure

Silver nanoparticles (AgNPs) are widely used in medical and commercial products for their unique antibacterial functions. However, the impact of AgNPs on human neural development is not well understood. To investigate the effect of AgNPs on human neural development, various doses of 20 nm citrate-coated AgNP (AgSC) were administered to human embryonic stem cell derived neural progenitors during the neuronal differentiation. Immunofluorescence staining with neuronal progenitor markers SOX2 (sex determining region Y-box 2) and Nestin (VI intermediate filament protein) showed that AgSC inhibited rosette formation, neuronal progenitor proliferation, and neurite outgrowth. Furthermore, AgSC promoted astrocyte activation and neuronal apoptosis. These adverse effects can be partially recovered with ascorbic acid. A genome-wide transcriptome analysis of both AgSC treated and untreated samples indicated that the most up-graduated genes were a group of Metallothionein (1F, 1E, 2A) proteins, a metal-binding protein that plays an essential role in metal homeostasis, heavy metal detoxification, and cellular anti-oxidative defence. The most significantly down-regulated genes were neuronal differentiation 6 (NEUROD6) and fork head box G1 (FOXG1). GO analyse indicated that the regulation of cholesterol biosynthetic process, neuron differentiation, synapse organization and pattern specification, oliogenesis, and neuronal apoptosis were the most impacted biological processes. KEGG pathway analyse showed that the most significantly impacted pathways were C5 isoprenoid, axon guidance, Notch, WNT, RAS-MAPK signalling pathways, lysosome, and apoptosis. Our data suggests that AgSCs interfered with metal homeostasis and cholesterol biosynthesis which induced oxidative stress, inhibited neurogenesis, axon guidance, and promoted apoptosis. Supplementation with ascorbic acid could act as an antioxidant to prevent AgSC-mediated neurotoxicity.

Metabolic profiling of nanosilver toxicity in the gills of common carp

Studies have shown silver nanoparticles (AgNPs) exposure can result in a series of toxic effects in fish gills. However, it is still unclear how AgNPs affect metabolite expression and their related molecular metabolic pathways in fish gills. In this study, we employed untargeted metabolomics to study the effects of AgNPs and silver supernatant ions on fish gill metabolites. The results showed that AgNPs can induce significant changes in 96 differentially expressed metabolites, which mainly affect amino acid metabolism and energy metabolism in fish gills. Among these metabolites, AgNPs specifically induce significant changes in 72 differentially expressed metabolites, including L-histidine, L-isoleucine, L-phenylalanine, and citric acid. These metabolites were significantly enriched in the pathways of aminoacyl-tRNA biosynthesis, ABC transporters, and the citrate cycle. In contrast, Ag+ supernatant exposure can specifically induce significant changes in 14 differentially expressed metabolites that mainly interfere with sphingolipid metabolism in fish gills. These specifically regulated fish gill metabolites include sphinganine, sphingosine, and phytosphingosine, which were significantly enriched in the sphingolipid metabolism pathway. Our results clearly reveal the effects and potential toxicity mechanisms of AgNPs on fish gill metabolites. Furthermore, our study further determined the unique functions of released silver ions in AgNPs toxicity in fish gills.

Impact of silver nanoparticles exposure on neuro-behavior, hematology, and oxidative stress biomarkers of African catfish (Clarias gariepinus)

Recently, silver nanoparticles (AgNPs) established a prospective value in aquaculture; however, extensive use afflicts fish and environment. Therefore, the current study represents a premier report to investigate the acute exposure of African catfish, Clarias gariepinus (B.) to AgNPs and the ethological alterations in a static renewal system. Additionally, AgNPs impact on blood profile, stress, brain activity, and branchial oxidative stress parameters were evaluated. Fish (50.71 ± 3.85 g) were exposed to different concentrations (0, 6.25, 12.5, 25, 50, and 100 mg L−1) of AgNPs for 96-h without water exchange. Finney's probit analysis was used to estimate the 96-h LC50 value of AgNPs which recorded 21.38 mg L−1. In comparison to the control, the AgNPs exposed fish exhibited different ethological responses such as surfacing for gasping air, restlessness, slow swimming movement, aggressiveness, and nervousness and the scores of these behaviors and mortalities reached the high values with increasing AgNPs concentrations. There were marked reductions in hematological indices (RBCs, Hb, Hct, and WBCs), acetylcholine esterase (AChE) activity, and oxidative stress indices (superoxide dismutase (SOD), catalase (CAT), and reduced glutathione content (GSH)) of exposed groups in an AgNPs dose-dependent manner relative to the control group. On the contrary, the levels of stress-mediated indices (glucose and cortisol) and 8 hydroxy 2 deoxyguanosine (8OH2dG) were markedly decreased in all AgNPs exposed groups as compared with the control group and the reduction increased with increasing the exposure concentration. We concluded that AgNPs exposure of C. gariepinus induced marked alterations in behavior, blood profile, neurological, and branchial antioxidant parameters, and the 96-h LC50 of AgNPs was 21.38 mg L−1 and this provides a basis for future applying AgNPs as a safe therapeutic agent after considering the acute toxicity.

Occupational exposure risk during spraying of biocidal paint containing silver nanoparticles

The study assessed potential to exceed occupational exposure limits while spraying paint with and without a silver nanoparticle biocidal additive. A tradesperson performed the tasks in a sealed chamber with filtered air supply. Integrated air sampling entailed transmission electron microscopy with energy dispersive X-ray analysis, direct-reading of particle number concentrations, and determination of silver mass concentration by NIOSH Method 7300. Silver nanoparticles were primarily embedded in paint spray droplets but also observed as isolated particles. Using an α-level of 0.05, median nanoparticle number concentrations did not differ significantly when spraying conventional vs. biocidal paint, although statistically significant differences were observed at specific particle size ranges <100 nm. The geometric mean concentration of total silver while spraying biocidal paint (n = 6) was 2.1 µg/m3 (95% CI: 1.5–2.8 µg/m3), and no respirable silver was detected (<0.50 µg/m3). The results address a lack of silver nanoparticle exposure data in construction and demonstrate the feasibility of a practical sampling approach. Given similar conditions, the measurements suggest a low probability of exceeding a proposed silver nanoparticle exposure limit of 0.9 µg/m3 as an airborne 8-hr time-weighted average respirable mass concentration. A full workday of exposure to respirable silver at the highest possible level in this study (<0.50 µg/m3) would not exceed the exposure limit, although limitations in comparing short task-based exposures to an 8-hr exposure limit must be noted. There was airflow in the study chamber, whereas exposure levels could increase over time in work environments lacking adequate ventilation. Potential to exceed the exposure limit hinged upon the respirable fraction of the paint mist, which could vary by material and application method. Additional research would improve understanding of silver nanoparticle exposure risks among construction trades, and biological responses to these exposures. Given the potential for exposure variability on construction jobsites, safety and health professionals should be cognizant of methods to assess and control silver nanoparticle exposures.

Modulation of Innate Immune Toxicity by Silver Nanoparticle Exposure and the Preventive Effects of Pterostilbene.

Silver nanoparticles pose a potential risk to ecosystems and living organisms due to their widespread use in various fields and subsequent gradual release into the environment. Only a few studies have investigated the effects of silver nanoparticles (AgNPs) toxicity on immunological functions. Furthermore, these toxic effects have not been fully explored. Recent studies have indicated that zebrafish are considered a good alternative model for testing toxicity and for evaluating immunological toxicity. Therefore, the purpose of this study was to investigate the toxicity effects of AgNPs on innate immunity using a zebrafish model and to investigate whether the natural compound pterostilbene (PTE) could provide protection against AgNPs-induced immunotoxicity. Wild type and neutrophil- and macrophage-transgenic zebrafish lines were used in the experiments. The results indicated that the exposure to AgNPs induced toxic effects including death, malformation and the innate immune toxicity of zebrafish. In addition, AgNPs affect the number and function of neutrophils and macrophages. The expression of immune-related cytokines and chemokines was also affected. Notably, the addition of PTE could activate immune cells and promote their accumulation in injured areas in zebrafish, thereby reducing the damage caused by AgNPs. In conclusion, AgNPs may induce innate immune toxicity and PTE could ameliorate this toxicity.

Light-scattering properties of microorganisms Desulfuromonas acetoxidans by influence of silver

The article deals with the concentration changes and relative content of bacterial cells of Desulfuromonas acetoxidans in the intervals of sizes 0.2–2.0 µm under the influence of nano silver particles. Correlation between these changes of light-scattering properties of bacterial cells and growth abilities of bacteria Desulfuromonas acetoxidans under inflence of silver nanoparticles and ions has been shown. The purpose of the work was to research the intensity of processes the change of indexes of the antioxidant system the cells of Desulfuromonas acetoxidans at influence of silver nanoparticles and silver nitrate. The influence of various concentrations of silver nanoparticles and silver nitrate on enzymatic activity of catalase and reduced glutathione synthesis by Desulfuromonas аcetoxidans cells under their cultivation with fumarate addition and with absence of sulphur has been determined. Specific catalase activity increased with enhancing of concentration and duration of bacterial cultivation under the addition of this salt. The highest specific catalase activity was determined on the second day of bacterial growth under the influence of all concentration range of investigated metal salt. The reduced glutathione content under silver nitrate and silver nanoparticles exposure varied depending on the cultivation time and metal concentration. The maximum reduced glutathione content has been observed. The result of catalase activity changes and glutathione content changes of sulfur-reducing D. acetoxidans bacteria cell-free extracts and has been investigated under the influence of different concentrations of Ag nanoparticles during four days of cultivation has been investigated.

Alterations in oxygen metabolism are associated to lung toxicity triggered by silver nanoparticles exposure

Along with the AgNP applications development, the concern about their possible toxicity has increasingly gained attention. As the respiratory system is one of the main exposure routes, the aim of this study was to evaluate the harmful effects developed in the lung after an acute AgNP exposure. In vivo studies using Balb/c mice intranasally instilled with 0.1 mg AgNP/kg b.w, were performed. 99mTc-AgNP showed the lung as the main organ of deposition, where, in turn, AgNP may exert barrier injury observed by increased protein content and total cell count in BAL samples. In vivo acute exposure showed altered lung tissue O2 consumption due to increased mitochondrial active respiration and NOX activity. Both O2 consumption processes release ROS triggering the antioxidant system as observed by the increased SOD, catalase and GPx activities and a decreased GSH/GSSG ratio. In addition, increased protein oxidation was observed after AgNP exposure. In A549 cells, exposure to 2.5 μg/mL AgNP during 1 h resulted in augment NOX activity, decreased mitochondrial ATP associated respiration and higher H2O2 production rate. Lung 3D tissue model showed AgNP-initiated barrier alterations as TEER values decreased and morphological alterations. Taken together, these results show that AgNP exposure alters O2 metabolism leading to alterations in oxygen metabolism lung toxicity. AgNP-triggered oxidative damage may be responsible for the impaired lung function observed due to alveolar epithelial injury.

Effects of silver nanoparticles on the anti-oxidant status and histological alterations in different organs in Indian mud crab Scylla Serrata

In medicine and many other fields, the use of silver nanoparticles is inevitable. The negative impacts of silver accumulated silver nanoparticles on the environment and organisms need to be taken into consideration. The studies on the effect of silver nanoparticles on bio-indicators such as marine invertebrates pave the way to regulate the usage of silver nanoparticles. In the present study, the effect of silver nanoparticles on the hepatopancreas of Indian mud crab, Scylla Serrata was studied. A 20ppm of silver nanoparticles was exposed to S. Serrata for ten days period. The morphological changes, the biochemical markers from hepatopancreas, histological analysis for hepatopancreas, gills and reproductive organs were examined. On the 2nd day exposure of silver nanoparticles showed the increased value of anti-oxidants and no morphological changes. But the 10th-day exposure shows the significantly reduced level of biochemical markers in the hepatopancreas and morphological changes were observed. The apoptotic cells and necrotic cells were recorded in hepatopancreas. Moreover, the cell architecture of gill tissues and reproductive tissues were observed. The silver nanoparticles in the concentration of 20ppm caused significant changes in the hepatopancreas of S. Serrata for ten days of exposure. The mechanism of silver nanoparticles needs to be studied to understand and protect models from the nanoparticles.

Effect of silver nanoparticles (AgNPs) exposure on microRNA expression and global DNA methylation in endothelial cells EA.hy926

The aim of this study was to determine the effect of AgNPs on the epigenome of endothelial cells EA.hy926, including the levels of expression of microRNAs (miRNAs) and global DNA methylation patterns. In addition, evaluation of the expression of inflammatory genes and the levels of VCAM-1 protein (miRNA-126 target) was performed. The expression levels of analyzed miRNAs (microRNAs-126, 155 and 146) were reduced significantly and there were not observed changes in inflammatory gene expression. Regarding the levels of protein vascular cell adhesion molecule 1 (VCAM-1), they increase significantly to 0.5 μM AgNPs at 24 h of exposure. As far as DNA methylation is concerned, we found that AgNPs induce a state of global hyper-methylation. In conclusion, it was demonstrated that direct contact between AgNPs and endothelial cells resulted in the dysregulation of highly enriched and vastly functional miRNAs and DNA hypermethylation, that may have multiple effects on endothelium function and integrity.

Toxicological alterations induced by subacute exposure of silver nanoparticles in Wistar rats.

Silver nanoparticles (AgNPs) have become crucial players in the field of medicine and various other industries. AgNPs have a wide array of applications, which includes production of electronic goods, cosmetics, synthesis of dyes, and printing inks, as well as targeted delivery of drugs to specialized cells inside the body. Even though humans readily come in contact with these particles, the organ-specific accumulation and resulting mechanisms of toxicity induced by inhaled AgNPs are still under investigation. The goal of this study was to determine the organ distribution of inhaled AgNPs and investigate the resulting systemic toxicity. To do this, male Wistar rats were exposed by inhalation to AgNPs for 4hr/day (200 parts per billion/day) for five consecutive days. The nanoparticles were generated using a laser ablation technique using a soft-landing ion mobility (SLIM) instrument. Inductively coupled plasma mass spectrometric (ICP-MS) analysis showed organ-specific accumulation of the nanoparticles, with the highest concentration present in the lungs, followed by the liver and kidneys. Nanoparticle distribution was characterized in the organs using scanning electron microscopy (SEM) and matrix-assisted laser desorption/ionization mass spectrometric (MALDI-MS) imaging. Bone marrow cytotoxicity assay of the cells from the femur of rats showed micronuclei formation and signs of cellular cytotoxicity. Moreover, rats displayed increased levels of circulating lactate and glutathione disulphide (GSSG), as determined by liquid chromatography-mass spectrometry (LC-MS) analysis. Collectively, our observations suggest that inhaled subacute exposure to AgNP results in accumulation of AgNPs in the lungs, liver, and kidneys, preferentially, as well as mediates induced systemic 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.

Changes in syntrophic microbial communities, EPS matrix, and gene-expression patterns in biofilm anode in response to silver nanoparticles exposure

Understanding the toxic effect of silver nanoparticles (AgNPs) on various biological wastewater treatment systems is of significant interest to researchers. In recent years, microbial electrochemical technologies have opened up new opportunities for bioenergy and chemicals production from organic wastewater. However, the effects of AgNPs on microbial electrochemical systems are yet to be understood fully. Notably, no studies have investigated the impact of AgNPs on a microbial electrochemical system fed with a complex fermentable substrate. Here, we investigated the impact of AgNPs (50 mg/L) exposure to a biofilm anode in a microbial electrolysis cell (MEC) fed with glucose. The volumetric current density was 29 ± 2.0 A/m3 before the AgNPs exposure, which decreased to 20 ± 2.2 A/m3 after AgNPs exposure. The biofilms produced more extracellular polymeric substances (EPS) to cope with the AgNPs exposure, while carbohydrate to protein ratio in EPS considerably increased from 0.4 to 0.7. Scanning electron microscope (SEM) imaging also confirmed the marked excretion of EPS, forming a thick layer covering the anode biofilms after AgNPs injection. Transmission electron microscope (TEM) imaging showed that AgNPs still penetrated some microbial cells, which could explain the deterioration of MEC performance after AgNPs exposure. The relative expression level of the quorum signalling gene (LuxR) increased by 30%. Microbial community analyses suggested that various fermentative bacterial species (e.g., Bacteroides, Synergistaceae_vadinCA02, Dysgonomonas, etc.) were susceptible to AgNPs toxicity, which led to the disruption of their syntrophic partnership with electroactive bacteria. The abundance of some specific electroactive bacteria (e.g., Geobacter species) also decreased. Moreover, decreased relative expressions of various extracellular electron transfer associated genes (omcB, omcC, omcE, omcZ, omcS, and pilA) were observed. However, the members of family Enterobacteriaceae, known to perform a dual function of fermentation and anodic respiration, became dominant after biofilm anode exposed to AgNPs. Thus, EPS extraction provided partial protection against AgNPs exposure.

Low Concentration Analysis of Silver Nanoparticles in Consumer Spray Products

The lack of regulations regarding the manufacture of nanoparticle-containing products has enabled the release of many consumer products into the market with uncorroborated claims. Silver nanoparticles are commonly used in consumer goods, particularly in medical and household products. This study was designed to evaluate the aerosol exposure of silver nanoparticles from two consumer spray products currently on the market that claim to contain silver nanoparticles for antibacterial purposes. The study relies on our current understanding of various sampling and analytical methods to effectively evaluate aerosolized nanoparticles, particularly at low concentrations. To characterize low-concentration nanoparticles, various sophisticated sampling methods, including a NanoScan scanning mobility particle sizer, an optical particle sizer, an impinger, and diffusion samplers, were utilized to quantify, collect, and analyze the chemical compositions of the aerosolized products. Our results show that while both products aerosolize silver particles when sprayed, the emitted nanoparticles contain a low concentration of silver and vary in size and overall chemical composition. Further investigation of silver nanoparticle commercial spray products is needed to assess exposure risk and inform health professionals, industrial hygienists, and the general public regarding disparities in product marketing claims and nanoparticle aerosol exposure.

Silver nanoparticles regulate autophagy through lysosome injury and cell hypoxia in prostate cancer cells.

With the rapid development of nanotechnology, nanomaterials are now being used for cancer treatment. Although studies on the application of silver nanoparticles in cancer treatment are burgeoning, few studies have investigated the toxicology mechanisms of autophagy in cancer cells under exposure to sublethal silver nanoparticles. Here, we clarified the distinct mechanisms of silver nanoparticles for the regulation of autophagy in prostate cancer PC-3 cells under sublethal exposure. Silver nanoparticle treatment caused lysosome injury, including the decline of lysosomal membrane integrity, decrease of lysosomal quantity, and attenuation of lysosomal protease activity, which resulted in blockage of autophagic flux. In addition, sublethal silver nanoparticle exposure activated AMP-activated protein kinase/mammalian target of rapamycin-dependent signaling pathway to modulate autophagy, which resulted from silver nanoparticles-induced cell hypoxia and energy deficiency. Taken together, the results show that silver nanoparticles could regulate autophagy via lysosome injury and cell hypoxia in PC-3 cells under sublethal dose exposure. This study will provide an experimental basis for the cancer therapy of nanomaterials.

Silver Nanoparticle Exposure Causes Pulmonary Structural Damage and Mitochondrial Dynamic Imbalance in the Rat: Protective Effects of Sodium Selenite.

BackgroundWith the increased application of Silver nanoparticles (AgNP), its potential concerns to the health of human beings remain to be defined. This study aims to explore the harmful effects of AgNP on lung tissue in animals and to examine the mechanisms of protection achieved by sodium selenite.MethodsSprague-Dawley(SD) rats were exposed to AgNP (200 μL,1mg/mL) through a single intratracheal instillation. Sodium selenite (0.2mg/kg) was i.p. injected. Malondialdehyde (MDA) and glutathione (GSH) were measured using a spectrophotometer. Histological outcomes and ultrastructural changes were assessed by hematoxylin and eosin (HE) staining and electronic microscopy. Caspases and mitochondrial fission and fusion markers were measured by Western blotting.ResultsThe histopathologic findings showed that AgNP significantly increased the thickness of alveolar septa, accumulation of macrophage, and the formation of pulmonary bullae and pulmonary consolidation. Ultrastructural studies showed localization of AgNP inside the mitochondria, hyperplasia and vacuolation of type I and type II alveolar cells, lysis of osmiophilic lamellar bodies, and swollen of the mitochondria. AgNP elevated MDA and reduced GSH levels. AgNP activated caspases-3, increased mitochondrial fission markers Dynamin-related protein 1 (Drp1) and phospho-Drp1(p-Drp1), and decreased fusion proteins optic atrophy 1 (Opa1) and mitofusins 2 (Mfn2). Treatment with sodium selenite for 7 days corrected the AgNP-caused alterations in morphological, ultrastructural, oxidative stress, caspase-3 activation and mitochondrial dynamic imbalance.ConclusionWe conclude that the exposure of AgNP causes lung tissue damage by enhances oxidative stress, activates caspases-3, and triggers mitochondrial dynamic imbalance towards fission. Sodium selenite effectively detoxifies the AgNP-induced damage to the lung tissue by preventing the above alterations.

Morphological comparative assessment of in vivo 2-week oral exposure of silver nanoparticles and silver sulfate on the mice liver

Currently the problem of the impact of nanoparticles and nanomaterials on human health remains to be poorly understood. As in our studies of the impact of silver nanoparticles on rats liver as well in works of other researchers there were investigated morphofunctional indices under peroral exposure. Although all researchers took different sizes, doses and concentrations of silver nanoparticles, various exposure time and different stabilizers, the same effects had been obtained, which, however, were occurred under both different doses and time of exposure. However, it was interesting to compare the impact of silver nanoparticles with reference substance - silver sulfate on the mice liver with the previously evaluated effect produced on the rats ’ liver. By ourselves there was executed the morphological comparative evaluation of in vivo oral 2-weeks exposure of 4 concentrations (0.1; 5; 50 and 500 mg/l) of silver nanoparticles with size of 14 nm, stable arabian gum 1:7 by weight, and of 4 similar concentrations of silver sulfate on the liver of male mice СВАхС57В1/6 weighing 25-35g. 2 groups were considered as control: intact mice and mice received gum in water. Results of the exposure were assessed according to 10 morphological and functional indices. The impact of nanosilver was shown to initiate from its concentration of 50 mg/l and to express in the gain of the index of alteration of the cytoplasm of hepatocytes with the increasing in both severity of steatosis and the number of micronecroses, persisting at the same level at concentrations of 500 mg/l and with the elevation of the index of alteration of nuclei of hepatocytes, while the similar effect develops under the influence of silver sulfate at a concentration of 500 mg/l only. The remaining investigated morphofunctional indices did not differ significantly in all groups of mice. Unlike previously executed studies on rats, mice appeared to be sensitive to the effects of nano-silver more than to silver sulfate.

Effects of Subcytotoxic Exposure of Silver Nanoparticles on Osteogenic Differentiation of Human Bone Marrow Stem Cells

Abstract Introduction: In vitro toxicology evaluations utilizing human stem cell models represent attractive alternatives to conventional animal models, which are not always predictive of human res...

Molecular and Morphological Evidence of Hepatotoxicity after Silver Nanoparticle Exposure: A Systematic Review, In Silico, and Ultrastructure Investigation

Silver nanoparticles (AgNPs) have been widely used in a variety of applications in innovative development; consequently, people are more exposed to this particle. Growing concern about toxicity from AgNP exposure has attracted greater attention, while questions about nanosilver-responsive genes and consequences for human health remain unanswered. By considering early detection and prevention of nanotoxicology at the genetic level, this study aimed to identify 1) changes in gene expression levels that could be potential indicators for AgNP toxicity and 2) morphological phenotypes correlating to toxicity of HepG2 cells. To detect possible nanosilver-responsive genes in xenogenic targeted organs, a comprehensive systematic literature review of changes in gene expression in HepG2 cells after AgNP exposure and in silico method, connection up- and down-regulation expression analysis of microarrays (CU-DREAM), were performed. In addition, cells were extracted and processed for transmission electron microscopy to examine ultrastructural alterations. From the Gene Expression Omnibus (GEO) Series database, we selected genes that were up- and down-regulated in AgNPs, but not up- and down-regulated in silver ion exposed cells, as nanosilver-responsive genes. HepG2 cells in the AgNP-treated group showed distinct ultrastructural alterations. Our results suggested potential representative gene data after AgNPs exposure provide insight into assessment and prediction of toxicity from nanosilver exposure.

Single-Cell Analysis Reveals that Chronic Silver Nanoparticle Exposure Induces Cell Division Defects in Human Epithelial Cells.

Multiple organizations have urged a paradigm shift from traditional, whole animal, chemical safety testing to alternative methods. Although these forward-looking methods exist for risk assessment and predication, animal testing is still the preferred method and will remain so until more robust cellular and computational methods are established. To meet this need, we aimed to develop a new, cell division-focused approach based on the idea that defective cell division may be a better predictor of risk than traditional measurements. To develop such an approach, we investigated the toxicity of silver nanoparticles (AgNPs) on human epithelial cells. AgNPs are the type of nanoparticle most widely employed in consumer and medical products, yet toxicity reports are still confounding. Cells were exposed to a range of AgNP doses for both short- and-long term exposure times. The analysis of treated cell populations identified an effect on cell division and the emergence of abnormal nuclear morphologies, including micronuclei and binucleated cells. Overall, our results indicate that AgNPs impair cell division, not only further confirming toxicity to human cells, but also highlighting the propagation of adverse phenotypes within the cell population. Furthermore, this work illustrates that cell division-based analysis will be an important addition to future toxicology studies.

Effects of Silver Nanoparticle Exposure on Germination and Early Growth of Pinus sylvestris and Alnus subcordata

The possible ecological toxicity of silver nanoparticles (AgNP) was evaluated based on germination and growth characteristics of Pinus sylvestris and Alnus subcordata. Seeds were exposed to different concentrations of AgNP in soil (0, 10, 20, 40, 80 and 100 mg/kg) and aqueous suspension (0, 10 and 20 mg/L). Then, seed germination percentage (GP%), speed of germination (S.G), seedling length (SL), as well as fresh and dry weights (FW and DW) were measured. The results showed that low concentration of AgNP (under 80 mg/kg) could be used without detrimental effects on the germination characteristics of P. sylvestris in the soil. Nevertheless, inhibitory effect of AgNP was observed at 10 mg/L for P. sylvestris in aqueous suspension. The dissimilar results in soil and aqueous suspension were due to the organic matters and clay minerals in the soil. There was no significant difference (p<0.01) among the treatments of A. subcordata, not only in soil but also in the aqueous suspension.