Genotoxicity of citrate-coated silver nanoparticles to human keratinocytes assessed by the comet assay and cytokinesis blocked micronucleus assay

Cyto-genotoxicity of crystalline and amorphous niobium (V) oxide nanoparticles in CHO-K1 cells

Niobium (V) oxide nanoparticles (NINPs) have been widely and increasingly applied in various health products and industrial processes. This merits further study of their toxicity. Here, we investigated the potential of NINPs to induce DNA damage, cytotoxicity, and chromosome instability in cultured CHO-K1 cells. NINPs were physico-chemically characterized. As assessed by comet assay, crystalline and amorphous NINPs were genotoxic at the highest concentrations evaluated. The cytokinesis-block micronucleus assay demonstrated that a 24-h treatment with NINPs, for the crystalline and the amorphous samples, significantly reduced the nuclear division cytotoxicity index. In addition, a 4-h treatment period of crystalline NINPs increased micronucleus (MNi) frequencies. MNi, nucleoplasmic bridges and nuclear buds were detected after exposure of the cells for 24 h to crystalline NINPs. In the amorphous sample, chromosome instability was restricted to the induction of MNi, in the 24-h treatment, detected at all tested concentrations. The fluorescence and dark field microscopy demonstrated the uptake of NINPs by CHO-K1 cells and an intracellular distribution outlining the nucleus. Our data advance understanding of the cytotoxic and genotoxic effects of NINPs and should be taken into consideration when setting up guidelines for their use in industrial or health products.

Genotoxicity of physical silver nanoparticles, produced by the HVAD method, for Chinchilla lanigera genome

Each year, growing demand for silver nanoparticles (AgNP) contributes to the search for alternative methods of their production. Stable AgNP with antibacterial properties, low toxicity to the environment and living organisms are especially valued. In the study presented here, an attempt was made to assess the toxicity of two AgNP solutions produced using the HVAD method to the Chinchilla lanigera genome. The AgNO₃ solution was the indicator and reference for the harmfulness of AgNP. The study was carried out in vitro on bone marrow cells isolated from Chinchilla lanigera bones. The genotoxicity was assessed by comet assay, following the treatment of cells with three silver solutions: unstable and sodium citrate-stabilized silver nanoparticles, as well as silver nitrate at three concentrations (5, 10 and 20 µg/L), after 3, 6 and 24 h. Based on the percentage of the DNA content in the comet tail and the tail moment, an increase in cell DNA integrity disruption was demonstrated in all tested variants: of solution, exposure time and concentration, compared to the control sample. A statistically significant correlation was determined between the level of induced DNA breaks and the concentration of the active solutions and the duration of their activity. A solution of silver nanoparticles stabilized with sodium citrate was shown to have the most harmful effect on bone marrow cells. Silver nitrate demonstrated a level of toxicity similar to these particles. Further studies are necessary to directly compare the genotoxic properties of AgNP produced using the HVAD method and the chemical method under the same conditions.

The Action-Networks of Nanosilver: Bridging the Gap between Material and Biology

The emergence of nanosilver (silver in nanoscale shapes and their assemblies) benefits the landscape of modern healthcare; however, this brings about concerns over its safety issues associated with an ultrasmall size and high mobility. By reviewing previous reporting details about the synthesis and characterization of nanosilver and its biological responses, a gap between materials synthesis and their biomedical uses is characterized by the insufficient understanding of the interacting and interplaying nanoscale actions of silver. To improve reporting quality and advance clinical translations, it is suggested that researchers have a comprehensive recognition of the "Indications for use" before designing innovative nanosilver-based materials and an "Action-network" concept addressing the acting range and strength of those nanoscale actions is implemented. Although this discussion is specific to nanosilver, the idea of "Indications for use" centered design and synthesis is generally applicable to other biomedical nanomaterials.

A harmonized and standardized in vitro approach produces reliable results on silver nanoparticles toxicity in different cell lines

Despite the widespread use of silver nanoparticles (AgNPs) in different fields and the amount of investigations available, to date, there are many contradictory results on their potential toxicity. In the present study, extensively characterized 20-nm AgNPs were investigated using optimized protocols and standardized methods to test several toxicological endpoints in different cell lines. The agglomeration/aggregation state of AgNPs in culture media was measured by dynamic light scattering (DLS). DNA and chromosomal damage on BEAS-2B and RAW 264.7 cells were evaluated by comet and micronucleus assays, while oxidative DNA damage by modified comet assay and 8-oxodG/8-oxodA detection. We also investigated immunotoxicity and immunomodulation by cytokine release and NO production in RAW 264.7 and MH-S cells, with or without lipopolysaccharide (LPS) stimulus. Transmission electron microscope (TEM) analysis was used to analyze cellular uptake of AgNPs. Our results indicate different values of AgNPs hydrodynamic diameter depending on the medium, some genotoxic effect just on BEAS-2B and no or slight effects on function of RAW 264.7 and MH-S in absence or presence of LPS stimulus. This study highlights the relevance of using optimized protocols and multiple endpoints to analyze the potential toxicity of AgNPs and to obtain reliable and comparable results.

Silver nanoparticles: Correlating particle size and ionic Ag release with cytotoxicity, genotoxicity, and inflammatory responses in human cell lines

The widespread use of silver nanoparticles (AgNPs), their many sources for human exposure, and the ability of AgNPs to enter organisms and induce general toxicological responses have raised concerns regarding their public health and environmental safety. To elucidate the differential toxic effects of polyvinylpyrrolidone-capped AgNPs with different primary particle sizes (i.e. 5, 50, and 75 nm), we performed a battery of cytotoxicity and genotoxicity assays and examined the inflammatory responses in two human cell lines (i.e. HepG2 and A549). Concentration-dependent decreases in cell proliferation and mitochondrial membrane potential and increases in cytokine (i.e. interleukin-6 and interleukin-8) excretion indicated disruption of mitochondrial function and inflammation as the main mediating factors of AgNPs-induced cytotoxicity. An incremental increase in genotoxicity with decreasing AgNPs diameter was noted in HepG2 cells, which was associated with S and G2/M accumulation and transcriptional activation of the GADD45α promoter as reflected by luciferase activity. Dose-related genetic damage, as indicated by Olive tail moment and micronucleus formation, was also observed in A549 cells, but these effects as well as the AgNPs-induced cytotoxicity were more associated with ionic Ag release from nanoparticles (NPs). In summary, the present study addressed different toxicity mechanisms of AgNPs, depending on the cell model, toxicological endpoint, particle size, and degree of Ag+ release from NPs. The results suggest that the GADD45α promoter-driven luciferase reporter cell system provided a rapid screening tool for the identification of genotoxic properties of NPs across a range of different sizes and concentrations.

Innovative Betulin Nanosuspension exhibits enhanced anticancer activity in a Triple Negative Breast Cancer Cell line and Zebrafish angiogenesis model

We present a nanosuspension of betulin, a BCS class II anticancer drug, particularly effective against resistant breast cancer. As anticancer efficacy of betulin is hampered by poor aqueous solubility, a nanosuspension with surface area was considered to enhance efficacy. An innovative approach wherein the betulin nanosuspension is generated instantaneously in situ, by adding a betulin preconcentrate (BeTPC) comprising drug and excipients, to aqueous medium, is successfully demonstrated. The optimal BeTPC when added to isotonic dextrose solution instantaneously generated an in situ nanosuspension (BeTNS-15) with high precipitation efficiency (92.7 ± 1.21%), average particle size (383.74 ± 7.24 nm) and good stability as per ICH guidelines. TEM revealed elongated particles while DSC and XRD indicated partial amorphization. Significantly higher cytotoxicity of BeTNS-15 (IC₅₀ 38.44 µg/ml) compared to betulin (BetS) (IC₅₀ 69.54 µg/ml) in the resistant triple negative human breast cancer cell line MDA-MB-231, was attributed to high intracellular uptake confirmed by HPLC and Imaging Flow cytometry (IFC). IFC confirmed superior anti-cancer efficacy of BeTNS-15 mediated by mitochondrial membrane disruption and inhibition of the G0/G1 phase. BeTNS-15 also exhibited significantly greater anti-angiogenic efficacy (p < 0.05) in the zebrafish model confirming superior efficacy. Simplicity of the innovative in situ approach coupled with superior efficacy proposes BeTNS as an innovative and highly promising anticancer formulation.

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

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

Cytokinesis-Block Micronucleus Assay Using Human Lymphocytes as a Sensitive Tool for Cytotoxicity/Genotoxicity Evaluation of AgNPs

Silver nanoparticles (AgNPs) are the most used nanomaterials worldwide due to their excellent antibacterial, antiviral, and antitumor activities, among others. However, there is scarce information regarding their genotoxic potential measured using human peripheral blood lymphocytes. In this work, we present the cytotoxic and genotoxic behavior of two commercially available poly(vinylpyrrolidone)-coated silver nanoparticle (PVP-AgNPs) formulations that can be identified as noncytotoxic and nongenotoxic by just evaluating micronuclei (MNi) induction and the mitotic index, but present enormous differences when other parameters such as cytostasis, apoptosis, necrosis, and nuclear damage (nuclear buds (NBUDs) and nucleoplasmic bridges (NPBs)) are analyzed. The results show that Argovit (35 nm PVP-AgNPs) and nanoComposix (50 nm PVP-AgNPs), at concentrations from 0.012 to 12 μg/mL, produce no changes in the nuclear division index (NDI) or micronuclei (MNi) frequency compared with the values found on control cultures of human blood peripheral lymphocytes from a healthy donor. Still, 50 nm PVP-AgNPs significantly decrease the replication index and significantly increase cytostasis, apoptosis, necrosis, and the frequencies of nuclear buds (NBUDs) and nucleoplasmic bridges (NPBs). These results provide evidence that the cytokinesis-block micronucleus (CBMN) assay using human lymphocytes and evaluating the eight parameters provided by the technique is a sensitive, fast, accurate, and inexpensive detection tool to support or discard AgNPs or other nanomaterials, which is worthwhile for continued testing of their effectiveness and toxicity for biomedical applications. In addition, it provides very important information about the role played by the [coating agent]/[metal] ratio in the design of nanomaterials that could reduce adverse effects as much as possible while retaining their therapeutic capabilities.

Phospholipids modifications in human hepatoma cell lines (HepG2) exposed to silver and iron oxide nanoparticles

Metallic nanoparticles such as silver (Ag NPs) and iron oxide (Fe₃O₄ NPs) nanoparticles are high production volume materials due to their applications in various consumer products, and in nanomedicine. However, their inherent toxicities to human cells remain a challenge. The present study was aimed at combining lipidomics data with common phenotypically-based toxicological assays to gain better understanding into cellular response to Ag NPs and Fe₃O₄ NPs exposure. HepG2 cells were exposed to different concentrations (3.125, 6.25, 12.5, 25, 50 and 100 µg/ml) of the nanoparticles for 24 h, after which they were assayed for toxic effects using toxicological assays like cytotoxicity, mutagenicity, apoptosis and oxidative stress. The cell membrane phospholipid profile of the cells was also performed using shotgun tandem mass spectrometry. The results showed that nanoparticles exposure resulted in concentration-dependent cytotoxicity as well as reduced cytokinesis-block proliferation index (CBPI). Also, there was an increase in the production of ROS and superoxide anions in exposed cells compared to the negative control. The lipidomics data revealed that nanoparticles exposure caused a modulation of the phospholipidome of the cells. A total of 155 lipid species were identified, out of which the fold changes of 23 were significant. The high number of differentially changed phosphatidylcholine species could be an indication that inflammation is one of the major mechanisms of toxicity of the nanoparticles to the cells.

Genotoxicity of Silver Nanoparticles

Silver nanoparticles (AgNPs) are widely used in diverse sectors such as medicine, food, cosmetics, household items, textiles and electronics. Given the extent of human exposure to AgNPs, information about the toxicological effects of such products is required to ensure their safety. For this reason, we performed a bibliographic review of the genotoxicity studies carried out with AgNPs over the last six years. A total of 43 articles that used well-established standard assays (i.e., in vitro mouse lymphoma assays, in vitro micronucleus tests, in vitro comet assays, in vivo micronucleus tests, in vivo chromosome aberration tests and in vivo comet assays), were selected. The results showed that AgNPs produce genotoxic effects at all DNA damage levels evaluated, in both in vitro and in vivo assays. However, a higher proportion of positive results was obtained in the in vitro studies. Some authors observed that coating and size had an effect on both in vitro and in vivo results. None of the studies included a complete battery of assays, as recommended by ICH and EFSA guidelines, and few of the authors followed OECD guidelines when performing assays. A complete genotoxicological characterization of AgNPs is required for decision-making.

Survival Mechanisms and Xenobiotic Susceptibility of Keratinocytes Exposed to Metal-Derived Nanoparticles

Metal-derived nanoparticles (Mt-NPs) are increasingly used in cosmetology due to their ultraviolet shielding (titanium dioxide [TiO₂]), antioxidant (cerium dioxide [CeO₂]), and biocidal (silver [Ag]) properties. In the absence of overt toxicity (i.e., cell death), Mt-NPs are considered safe for cosmetic applications. However, there is little understanding about the mechanisms involved in the survival of keratinocytes exposed to subtoxic levels of Mt-NPs. Human keratinocytes (HaCaT) were exposed subacutely to subtoxic concentrations (≤30 μg/mL, 48-72 h) of rutile (r) TiO₂ (cylindrical), CeO₂ (cubic) and Ag (spherical) with a core/hydrodynamic size of <50/<100 nm and >98% purity. Mt-NP uptake was indirectly quantified by changes in the light side scatter, where the kinetics (time/dose-response) suggested that the three types of Mt-NPs were similarly uptaken by keratinocytes. rTiO₂ and CeO₂, but not Ag-NPs, increased autophagy, whose inhibition prompted cell death. No increase in the steady-state levels of reactive oxygen species (ROS) was induced by exposure to any of the Mt-NPs tested. Interestingly, intracellular Ag-NP aggregates observed an increased far-red autofluorescence (≥740 nm em), which has been ascribed to their binding to thiol molecules such as glutathione (GSH). Accordingly, inhibition of GSH synthesis, but not the impairment of oxidized GSH recycling, sensitized keratinocytes to Ag-NPs suggesting that GSH homeostasis, and its direct scavenging of Ag-NPs, but not ROS, is essential for keratinocyte survival upon exposure to Ag-NP. rTiO₂ and Ag, but not CeO₂-NPs, compromised metabolic flux (glycolysis and respiration), but ATP levels were unaltered. Finally, we also observed that exposure to Mt-NPs sensitized keratinocytes to non-UV xenobiotic exposure (arsenite and paraquat). Our results demonstrate the differential contribution of autophagy and GSH homeostasis to the survival of human keratinocytes exposed to subtoxic concentrations of Mt-NPs and highlight the increased susceptibility of keratinocytes exposed to Mt-NPs to a second xenobiotic insult.

Gamma-hexalactone flavoring causes DNA lesion and modulates cytokines secretion at non-cytotoxic concentrations

BACKGROUND

The γ-hexalactone is a flavoring agent for alcoholic beverages, teas, breads, dairy products, coffees, buttery products among others. It presents low molecular weight and exhibits sweet fruity aroma with nuances of nuts. As far as we know, both literature and government regulations have gaps regarding the safe use of the γ-hexalactone. In this context, the main objective of this work was to evaluate the effects of γ-hexalactone through in silico and in vitro approaches.

METHODS

The in silico analysis was performed through four free online platforms (admetSAR, Osiris Property Explorer^®, pkCSM platform and PreADMET) and consisted of comparative structural analysis with substances present in databases. The computational prediction was performed in the sense of complement and guide the in vitro tests. Regarding in vitro investigations, screening of cytotoxicity (assessed by cell proliferation and viability parameters) in lymphocytes exposed to γ-hexalactone for 72 h were carried out previously to determine non-cytotoxic concentrations. Following this screening, concentrations of 5.15, 0.515, and 0.0515 μM were selected for the study of the respective potentials: genotoxic (assessed by DNA comet assay), chromosomal mutation (analysis of micronucleus frequency) and immunomodulatory (cytokine quantification using ELISA immunoassay). The results of in vitro assays were compared by one-way analysis of variance (ANOVA), followed by Bonferroni's post hoc test, conducted by statistic software.

RESULTS

The platform PreADMET pointed out that γ-hexalactone is potentially mutagenic and carcinogenic. The comet assay data corroborate with these results demonstrating that γ-hexalactone at 5.15 μM caused lymphocytes DNA damage. In relation to cytokine secretion, the results indicate that lymphocytes were activated by γ-hexalactone at non-cytotoxic concentrations, involving an increase in the IL-1 levels in all tested concentrations, ranging from approximately 56 to 93%. The γ-hexalactone only at 5.15 μM induced increase in the levels of IL-6 (~ 60%), TNF-α (~ 68%) and IFN-γ (~ 29%), but decreased IL-10 (~ 46%) in comparison with the negative control (p < 0.05). No change was observed in total lymphocytes or in cell viability at the concentrations tested.

CONCLUSIONS

In summary, the γ-hexalactone demonstrated immunomodulatory and genotoxic effects at non-cytotoxic concentrations in healthy lymphocytes.

The effect of biogenic manufactured silver nanoparticles on human endothelial cells and zebrafish model

Human health and environment have been continuously getting exposure to toxic chemicals including nanomaterial; therefore, nontoxicity has recently attracted huge amount of attention. In this study, RU-AgNPs were synthesized by a green synthesis procedure and evaluated for their toxicity in human umbilical vein endothelial cells (HUVECs) as well as on zebrafish embryos via apoptotic pathway. The synthesized RU-AgNPs were average in size (20-25 nm) with a negative surface charge of -13.43 mV. As a result, RU-AgNPs potentiated the formation of reactive oxygen species (ROS) in HUVECs as confirmed by the results of immunoblotting analysis using apoptotic markers, such as Bax, Bcl2, and cytochrome C. Moreover, the induction of apoptosis in HUVECs was also authenticated in a dose-dependent manner after the treatment with RU-AgNPs by the Incucyte analysis. In vivo trials conducted on zebrafish visualized the mortality, malformation, and imbalanced in the heart rate, and cell death of the whole embryo, including severe morphological changes in the yolk sac and the tail of zebrafish. Furthermore, the results of western blot analysis demonstrated the increasing intensity of apoptotic biomarkers such as Bax, Bcl2, and Cyto C, including enhanced production of ROS, validating the cell death in zebrafish larvae. In addition, chemically functionalized silver nanoparticles found to be more cytotoxic than biogenic functionalized silver nanoparticles. Above-mentioned findings clearly demonstrate that Ru-AgNPs cause the toxicity via ROS-induced apoptotic pathway. Therefore, it is necessary to decide RU-AgNPs toxicity levels before being used in any biomedical application.

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.

Genotoxic effects of silver nanoparticles with/without coating in human liver HepG2 cells and in mice

With the rapid expansion of human exposure to silver nanoparticles (AgNPs), the genotoxicity screening is critical to the biosafety evaluation of nanosilver. This study assessed DNA damage and chromosomal aberration in the human hepatoma cell line (HepG2) as well as the effects on the micronucleus of bone marrow in mice induced by 20 nm polyvinylpyrrolidone-coated nanosilver (PVP-AgNPs) and 20 nm bare nanosilver (AgNPs). Our results showed that the two types of AgNPs, in doses of 20-160 μg/mL, could cause genetic toxicological changes on HepG2 cells. The DNA damage degree of HepG2 cells in 20 nm AgNPs was higher than that in 20 nm PVP-AgNPs, while the 20 nm PVP-AgNPs caused more serious chromosomal aberration than 20 nm AgNPs. Both kinds of AgNPs caused genetic toxicity in a dose-dependent manner in HepG2 cells. In the micronucleus test on mouse bone marrow cells, in doses of 10, 50 and 250 mg/kg body weight administered orally for 28 days once a day, the two kinds of AgNPs have no obvious inhibitory effect on the mouse bone marrow cells, and the effect of chromosome aberration could be documented at the high dose of 250 mg/kg. These results suggest that AgNPs have genotoxic effects in HepG2 cells and limited effects on bone marrow in mice; both in vitro and in vivo tests could be of great importance on the evaluation of genotoxicity of nanosilver. These findings can provide useful toxicological information that can help to assess genetic toxicity of nanosilver in vitro and in vivo.

Assessment of in vivo genotoxicity of citrated-coated silver nanoparticles via transcriptomic analysis of rabbit liver tissue

Background

Silver nanoparticles (AgNPs) are widely used in industrial and household applications, arousing concern regarding their safety in humans. The risks posed by stabilizer-coated AgNPs continue to be unclear, and assessing their toxicity is for an understanding of the safety issues involved in their use in various applications.

Purpose

We aimed to investigated the long-term toxicity of citrate-coated silver nanoparticles (cAgNPs) in liver tissue using several toxicity tests and transcriptomic analysis at 7 and 28 days after a single intravenous injection into rabbit ear veins (n=4).

Materials and methods

The cAgNPs used in this study were in the form of a 20% (w/v) aqueous solution, and their size was 7.9±0.95 nm, measured using transmission electron microscopy. The animal experiments were performed based on the principles of good laboratory practice.

Results

Our results showed that the structure and function of liver tissue were disrupted due to a single exposure to cAgNPs. In addition, in vivo comet assay showed unrepaired genotoxicity in liver tissue until 4 weeks after a single injection, suggesting a potential carcinogenic effect of cAgNPs. In our transcriptomic analysis, a total of 244 genes were found to have differential expression at 28 days after a single cAgNP injection. Carefully curated pathway analysis of these genes using Pathway Studio and Ingenuity Pathway Analysis tools revealed major molecular networks responding to cAgNP exposure and indicated a high correlation of the genes with inflammation, hepatotoxicity, and cancer. Molecular validation suggested potential biomarkers for assessing the toxicity of accumulated cAgNPs.

Conclusion

Our investigation highlights the risk associated with a single cAgNP exposure with unrepaired damage persisting for at least a month.