Protective effect of sulphoraphane against oxidative stress mediated toxicity induced by CuO nanoparticles in mouse embryonic fibroblasts BALB 3T3

Effects of copper oxide nanoparticles on reproductive system of zebrafish

Copper oxide nanoparticles (CuO NPs) were regarded as the versatile materials in daily life and the in-depth evaluation of their biological effects is of great concern. Herein the female and male zebrafishes were chosen as the model animals to analyze the reproductive toxicity caused by CuO NPs at low concentration (10, 50 and 100 μg/L) After 20-days exposure, the structure of zebrafish ovary and testis were impaired. Moreover, the contents of 17β-estradiol (E2) in both females and males were increased, while the contents of testosterone (T) were decreased, indicating the imbalanced sex hormones caused by CuO NPs. The expression of genes along the hypothalamic pituitary-gonad (HPG) axis, were examined with quantitative real-time PCR to further evaluate the toxic mechanisms. Meanwhile, the levels of erα/er2β and cyp19a in female zebrafishes and erα/er2β, lhr, hmgra/hmgrb, 3βhsd and 17βhsd in male zebrafishes were obviously up-regulated. While, the level of αr was obviously down-regulated in female and male zebrafishes. Thus, the obtained data uncovered that long-term exposure of CuO NPs with low dose could trigger the endocrine disorder, resulting in the disturbance of E2 and T level, inhibition of gonad development, and alteration of HPG axis genes. In brief, this study enriched the toxicological data of NPs on aquatic vertebrates and provided the theoretical support for assessing the environmental safety of NPs.

Ameliorative role of nanocurcumin against the toxicological effects of novel forms of Cuo as nanopesticides: a comparative study

Copper oxide nanoparticles (CuONPs) have a wide range of uses in agricultural applications. Nanocurcumin (NCur) acts as an antioxidant treatment. The goal of the study is to reduce the toxicity resulting from the use of CuONPs as nanopesticides on living organisms by inducing changes in the morphological shape of CuONPs or treating it with NCur. So, we induced a comparative study between three shapes of CuONPs: CuO nanosphere (CuONSp), CuO nanosheet (CuONS), and CuO nanoflower (CuONF). We characterize each nano-form by using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (HRTEM), and Zetasizer HT device; 36 rats were divided into six groups (n = 6): 1st group was the control group; 2nd group received 50 mg/kg/day of NCur orally for 30 days; 3rd, 4th, and 5th groups received orally 50 mg/kg/day of CuONSp, CuONS, and CuONF, respectively, for 30 days; 6th group received 50 mg/kg/day CuONSp plus 50 mg/kg/day of NCur orally for 30 days. An elevation occurred in malondialdehyde (MDA), liver and kidney functions, tumor necrosis factor-alpha (TNF-α), and B-cell lymphoma 2 (Bcl2) by CuONSp > CuONS > CuONF, respectively. An inhibition occurred in glutathione (GSH), superoxidase (SOD) catalase (CAT), apoptotic Bax gene (Bax), histopathological, and ultrastructural alterations by CuONSp < CuONS < CuONF, respectively. NCur ameliorated these alternations. In conclusion, CuONF is a better form compared to other forms of nanopesticide in agriculture due to its lower toxicity. NCur decreased the biological alternations which induced by CuONSp due to its antioxidant and anti-apoptotic properties.

Solanum Procumbens-Derived Zinc Oxide Nanoparticles Suppress Lung Cancer In Vitro through Elevation of ROS

Lung cancer is one of the cancers with high mortality rate. The current therapeutic regimens have only limited success rate. The current work highlights the potential of Solanum procumbens-derived zinc oxide nanoparticle (SP-ZnONP)-induced apoptosis in A549 lung cancer cells. Synthesized nanoparticles were confirmed by UV-Vis spectrophotometry, X-ray diffraction (XRD), dynamic light scattering analysis (DLS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and photoluminescence analysis. Lactate dehydrogenase (LDH), cytotoxicity, and cell viability assays revealed that the SP-ZnONP caused the cell death and the inhibition concentration (IC₅₀) was calculated to be 61.28 μg/mL. Treatment with SP-ZnONPs caused morphological alterations in cells, such as rounding, which may have been caused by the substance's impact on integrins. Acridine orange/ethidium bromide dual staining revealed that the cells undergo apoptosis in a dose-dependent manner, which indicates the cell death. Furthermore, reactive oxygen species (ROS) were examined and it was shown that the nanoparticles elevated ROS levels, which led to lipid peroxidation. In short, the SP-ZnONPs increase the level of ROS, which in turn causes lipid peroxidation results in apoptosis. On the other hand, the SP-ZnONPs decrease nitric oxide level in A549 cells in a dose-dependent manner, which also supports the apoptosis. In conclusion, SP-ZnONPs would become a promising treatment option for lung cancer.

The Yin and Yang of epigenetics in the field of nanoparticles

Nanoparticles (NPs) have become a very exciting research avenue, with multitudinous applications in various fields, including the biomedical one, whereby they have been gaining considerable interest as drug carriers able to increase bioavailability, therapeutic efficiency and specificity of drugs. Epigenetics, a complex network of molecular mechanisms involved in gene expression regulation, play a key role in mediating the effect of environmental factors on organisms and in the etiology of several diseases (e.g., cancers, neurological disorders and cardiovascular diseases). For many of these diseases, epigenetic therapies have been proposed, whose application is however limited by the toxicity of epigenetic drugs. In this review, we will analyze two aspects of epigenetics in the field of NPs: the first is the role that epigenetics play in mediating nanotoxicity, and the second is the possibility of using NPs for delivery of "epi-drugs" to overcome their limitations. We aim to stimulate discussion among specialists, specifically on the potential contribution of epigenetics to the field of NPs, and to inspire newcomers to this exciting technology.

Polyphenol effects on CuO-nanoparticle-mediated DNA damage, reactive oxygen species generation, and fibroblast cell death

The ability of ten polyphenolic antioxidants to prevent CuO nanoparticle (NPCuO) and H2O2-mediated DNA damage and cytotoxicity was investigated. Five of the polyphenols (MEPCA, PREGA, MEGA, ECG, and EGCG) prevent NPCuO/H2O2-mediated DNA damage (IC50 values of 7.5-800 μM), three have no effect (PCA, VA, and EC), and two (GA and EGC) result in increased DNA damage. Most polyphenols had similar antioxidant/prooxidant activity in the presence of NPCuO or free copper ions. Electron paramagnetic resonance (EPR) spectroscopy of reactive oxygen species (ROS) generated by NPCuO/H2O2 in the presence of representative polyphenols correlate with results of DNA damage studies: in the presence of NPCuO/H2O2, MEPCA prevents ROS formation, VA has no effect on ROS levels, and EGC increases ROS levels. EPR results with CuO nanoparticles washed to remove dissolved copper in solution (wCuO) in the presence of H2O2/ascorbate suggest that MEPCA prevents ROS formation on the nanoparticle surface in addition to preventing ROS formation from dissolved copper. In mouse fibroblast (L929) cells, combining NPCuO with H2O2 results in significantly greater cytotoxicity than observed for either component alone. After 3 h incubation with MEPCA or MEGA, the viability loss in L929 cells induced by NPCuO/H2O2 challenge was significantly rescued at physiologically relevant polyphenol levels (1 μM). These studies show that polyphenols can protect DNA and inhibit cytotoxicity generated by NPCuO under oxidative stress conditions.

Cytotoxicity and Genotoxicity of Copper oxide Nanoparticles in chickens

Copper oxide nanoparticles (CuO-NPs) are consciously used to control the growth of bacteria, fungi, and algae. Several studies documented the beneficial and hazardous effects of CuO-NPs on human cells and different experimental animals but there are not many studies that report the effect of CuO-NPs in poultry. Therefore, the present study was performed to investigate the dose-dependent effects of copper oxide nanoparticles on the growth performance, immune status, oxidant/antioxidant capacity, DNA status, and histological structures of most edible parts of broiler chickens (muscle, heart, liver, spleen, and kidneys). The experiment was carried out on 90 1-day-old broiler chicks (Cobb 500) which were divided into three experimental groups (n = 30) in three replicates (n = 10). Group 1 was kept as a control group and did not receive copper oxide nanoparticles. Groups 2 and 3 received CuO-NPs by oral gavage at dose 5 mg/kg and 15 mg/kg bwt respectively at 1, 7, 14, 21, 28, and 35 days of the life of the chickens. An increase in the amount of feed intake and weight was recorded every week, and finally, the food conversion ratio (FCR) was calculated. Our results showed dose-dependent increases in malondialdehyde levels, copper contents, DNA fragmentation percent, and microscopic scoring in different examined organs of CuO-NPs-receiving groups associated with a remarkable reduction in weight gain, food conversion ratio, catalase activity, and antibody titer of both New Castle and Avian Influenza viruses. Histopathological alterations were observed in both groups receiving CuO-NPs with some variations in its severity. Our study concluded that CuO-NPs are considered cytotoxic and we recommend not adding them to poultry feed.

An Overview of the Beneficial Role of Antioxidants in the Treatment of Nanoparticle-Induced Toxicities

Nanoparticles (NPs) are used in many products and materials for humans such as electronics, in medicine for drug delivery, as biosensors, in biotechnology, and in agriculture, as ingredients in cosmetics and food supplements. Besides that, NPs may display potentially hazardous properties on human health and the environment as a consequence of their abundant use in life nowadays. Hence, there is increased interest of researchers to provide possible therapeutic agents or dietary supplements for the amelioration of NP-induced toxicity. This review summarizes the new findings in the research of the use of antioxidants as supplements for the prevention and alleviation of harmful effects caused by exposure of organisms to NPs. Also, mechanisms involved in the formation of NP-induced oxidative stress and protective mechanisms using different antioxidant substances have also been elaborated. This review also highlights the potential of naturally occurring antioxidants for the enhancement of the antioxidant defense systems in the prevention and mitigation of organism damage caused by NP-induced oxidative stress. Based on the presented results of the most recent studies, it may be concluded that the role of antioxidants in the prevention and treatment of nanoparticle-induced toxicity is unimpeachable. This is particularly important in terms of oxidative stress suppression.

An Overview of the Beneficial Role of Antioxidants in the Treatment of Nanoparticle-Induced Toxicities

Nanoparticles (NPs) are used in many products and materials for humans such as electronics, in medicine for drug delivery, as biosensors, in biotechnology, and in agriculture, as ingredients in cosmetics and food supplements. Besides that, NPs may display potentially hazardous properties on human health and the environment as a consequence of their abundant use in life nowadays. Hence, there is increased interest of researchers to provide possible therapeutic agents or dietary supplements for the amelioration of NP-induced toxicity. This review summarizes the new findings in the research of the use of antioxidants as supplements for the prevention and alleviation of harmful effects caused by exposure of organisms to NPs. Also, mechanisms involved in the formation of NP-induced oxidative stress and protective mechanisms using different antioxidant substances have also been elaborated. This review also highlights the potential of naturally occurring antioxidants for the enhancement of the antioxidant defense systems in the prevention and mitigation of organism damage caused by NP-induced oxidative stress. Based on the presented results of the most recent studies, it may be concluded that the role of antioxidants in the prevention and treatment of nanoparticle-induced toxicity is unimpeachable. This is particularly important in terms of oxidative stress suppression.

Nanotoxicity: a challenge for future medicine

Background/aim

Due to nanomaterials’ potential benefits for diagnosis and treatment, they are widely used in medical applications and personal care products. Interaction of nanomaterials, which are very small in size, with tissue, cell and microenvironment, can reveal harmful effects that cannot be created with chemically identical and larger counterparts in biological organisms. In this review, a challenge for future medicine, nanotoxicity of nanomaterials is discussed.

Materials and methods

A detailed review of related literature was performed and evaluated as per medical applications of nanomaterials their toxicity.

Results and conclusion

Most authors state “the only valid technology will be nanotechnology in the next era”; however, there is no consensus on the impact of this technology on humankind, environment and ecological balance. Studies dealing with the toxic effect of nanomaterials on human health have also varied with developing technology. Nanotoxicology studies such as in vivo-like on 3D human organs, cells, advanced genetic studies, and -omic approaches begin to replace conventional methods. Nanotoxicity and adverse effects of nanomaterials in exposed producers, industry workers, and patients make nanomaterials a double-edged sword for future medicine. In order to control and tackle related risks, regulation and legislations should be implemented, and researchers have to conduct joint multidisciplinary studies in various fields of medical sciences, nanotechnology, nanomedicine, and biomedical engineering.

Cupric Oxide Nanoparticles Induce Cellular Toxicity in Liver and Intestine Cell Lines

Purpose: The wide application of cupric oxide nanoparticles (copper (II) oxide, CuO-NPs) in various fields has increased exposure to the kind of active nanomaterials, which can cause negative effects on human and environment health. Although CuO-NPs were reported to be harmful to human, there is still a lack information related to their toxic potentials. In the present study, the toxic potentials of CuO-NPs were evaluated in the liver (HepG2 hepatocarcinoma) and intestine (Caco-2 colorectal adenocarcinoma) cells. Methods: After the characterization of particles, cellular uptake and morphological changes were determined. The potential of cytotoxic, genotoxic, oxidative and apoptotic damage was investigated with several in vitro assays. Results: The average size of the nanoparticles was 34.9 nm, about 2%-5% of the exposure dose was detected in the cells and mainly accumulated in different organelles, causing oxidative stress, cell damages, and death. The IC50 values were 10.90 and 10.04 µg/mL by MTT assay, and 12.19 and 12.06 µg/mL by neutral red uptake (NRU) assay, in HepG2 and Caco-2 cells respectively. Apoptosis assumes to the main cell death pathway; the apoptosis percentages were 52.9% in HepG2 and 45.5% in Caco-2 cells. Comet assay result shows that the highest exposure concentration (20 µg/mL) causes tail intensities about 9.6 and 41.8%, in HepG2 and Caco-2 cells, respectively. Conclusion: CuO-NPs were found to cause significant cytotoxicity, genotoxicity, and oxidative and apoptotic effects in both cell lines. Indeed, CuO-NPs could be dangerous to human health even if their toxic mechanisms should be elucidated with further studies.

Reduction of the Cytotoxicity of Copper (II) Oxide Nanoparticles by Coating with a Surface-Binding Peptide

Copper (II) oxide nanoparticles (CuO-NPs) have been studied as potential antimicrobial agents, similar to silver or platinum nanoparticles. However, the use of excess NPs is limited by their safety and toxicity in beneficial microflora and human cells. In this study, we evaluated the cytotoxicity of CuO-NPs by coating with a novel cyclic peptide, CuO binding peptide 1 (CuBP1), cyclic-SCATPFSPQVCS, which binds to the surface of CuO-NPs. CuBP1 was identified using biopanning of a T7 phage display system and was found to promote the aggregation of CuO-NPs under mild conditions. The treated CuO-NPs with CuBP1 caused the reduction of the cytotoxicity against Escherichia coli, Lactobacillus helveticus, and five other microorganisms, including bacteria and eukaryotes. Similar effects were also demonstrated against human embryonic kidney (HEK293) cells in vitro. Our findings suggested that the CuO-NPs coated with a surface-binding peptide may have applications as a safe antimicrobial agent without excessive cytotoxic activity against beneficial microflora and human cells. Moreover, a similar tendency may be achieved with other metal particles, such as silver or platinum NPs, by using optimal metal binding peptides.

Fatty Acid Potassium Had Beneficial Bactericidal Effects and Removed Staphylococcus aureus Biofilms while Exhibiting Reduced Cytotoxicity towards Mouse Fibroblasts and Human Keratinocytes

Wounds frequently become infected or contaminated with bacteria. Potassium oleate (C18:1K), a type of fatty acid potassium, caused >4 log colony-forming unit (CFU)/mL reductions in the numbers of Staphylococcus aureus and Escherichia coli within 10 min and a >2 log CFU/mL reduction in the number of Clostridium difficile within 1 min. C18:1K (proportion removed: 90.3%) was significantly more effective at removing Staphylococcus aureus biofilms than the synthetic surfactant detergents sodium lauryl ether sulfate (SLES) (74.8%, p < 0.01) and sodium lauryl sulfate (SLS) (78.0%, p < 0.05). In the WST (water-soluble tetrazolium) assay, mouse fibroblasts (BALB/3T3 clone A31) in C18:1K (relative viability vs. control: 102.8%) demonstrated a significantly higher viability than those in SLES (30.1%) or SLS (18.1%, p < 0.05). In a lactate dehydrogenase (LDH) leakage assay, C18:1K (relative leakage vs. control: 108.9%) was found to be associated with a significantly lower LDH leakage from mouse fibroblasts than SLES or SLS (720.6% and 523.4%, respectively; p < 0.05). Potassium oleate demonstrated bactericidal effects against various species including Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Clostridium difficile; removed significantly greater amounts of Staphylococcus aureus biofilm material than SLES and SLS; and maintained fibroblast viability; therefore, it might be useful for wound cleaning and peri-wound skin.

Pro- and anti-inflammatory effects of sulforaphane on placental cytokine production

Placental inflammation increases the risk of adverse pregnancy outcomes and possibly neurodevelopmental disorders in the offspring. Previous research suggests it may be possible to modulate the placental immune response to bacteria to favor an anti-inflammatory phenotype with dietary factors. Sulforaphane (SFN) is a dietary supplement with known anti-inflammatory activities, however, its effects on placental cytokine production are unclear. Therefore, we evaluated the effects of SFN on biomarkers of inflammation and neurodevelopment under basal conditions and a setting of mild infection. Placental explant cultures were established and treated with up to 10 μM SFN in the presence and absence of 10⁷ CFU/ml heat-killed E. coli. Concentrations of IL-1β, TNF-α, IL-6, sgp130, HO-1 and BDNF in conditioned medium were quantified by immunoassay. SFN increased antioxidant HO-1 expression in the absence, but not the presence, of infection. SFN inhibited IL-1β and IL-10, but tended to promote, TNF-α production by bacteria-stimulated cultures. IL-6 and BDNF were inhibited by SFN irrespective of co-treatment with E.coli. A negative regulator of IL-6 signaling, sgp130, was increased by SFN under basal conditions, but not in E. coli-stimulated cultures. These results suggest that SFN has mixed effects on the placenta inhibiting both pro-inflammatory (IL-1β) and anti-inflammatory factors (IL-10) but promoting regulators of oxidative stress and inflammation (HO-1 and sgp130) in an infection-dependent manner.

Toxicity of Copper Oxide (CuO) Nanoparticles on Human Blood Lymphocytes

CuO nanoparticles (CuO-NPs) serve several important functions in human life, particularly in the fields of medicine, engineering, and technology. These nanoparticles have been utilized as catalysts, semiconductors, sensors, gaseous and solid ceramic pigments, and magnet rotatable devices. Further use for CuO-NPs has been employed in the pharmaceutical industry especially in the production of anti-microbial fabric treatments or prevention of infections caused by Escherichia coli and methicillin-resistant Staphylococcus aureus. Two key potential routes of exposure to CuO-NPs exist through inhalation and skin exposure. Toxicity of these nanoparticles has been reported in various studies; however, no study as of yet has investigated the complete cellular mechanisms involved in CuO-NPs toxicity on human cells. The aim of this study was to determine the cytotoxicity of CuO-NPs on human blood lymphocytes. Blood lymphocytes were obtained from healthy male subjects through the use of Ficoll polysaccharide subsequently by gradient centrifugation. The following parameters were assayed in blood lymphocytes after a 6-h incubation with different concentrations of CuO-NPs: cell viability, reactive oxygen species (ROS) formation, lipid peroxidation, cellular glutathione levels, and mitochondrial and lysosomal damage. Our results demonstrate that CuO-NPs, in particular, decreased cell viability in a concentration-dependent manner and the IC50 determined was 382 μM. CuO-NP cytotoxicity was associated with significant increase at intracellular ROS level and loss of mitochondrial membrane potential and lysosomal membrane leakiness. Hence, CuO-NPs are shown to effectively induce oxidative stress in addition to inflict damage on mitochondria and lysosomes in human blood lymphocytes.

Mechanistic insight to ROS and Apoptosis regulated cytotoxicity inferred by Green synthesized CuO nanoparticles from Calotropis gigantea to Embryonic Zebrafish

With the rapid development of nanotechnology, much has been anticipated with copper oxide nanoparticles (CuO NP) due to their extensive industrial and commercial application. However, it has raised concern over the environmental safety and human health effects. In this study, CuO nanoparticles were synthesized using the green method with floral extract of Calotropis gigantea and characterized by standard physiochemical techniques like DLS, Zeta potential determination, UV- Visible Spectroscopy, XRD, FTIR, FESEM, and TEM. Mechanistic cytotoxicity studies were performed using experimental and computational assays including morphological analysis, hatching, and viability rate analysis along with ROS and apoptosis analysis. Physiochemical characterization of CuO NP determined the size and zeta potential of synthesized nanoparticles to be 30 ± 09 nm to 40 ± 2 nm and -38 mV ± 12 mV respectively. Cytotoxicity evaluation with Zebrafish revealed malfunctioned organ development with differential viability and hatching rate at 48 hpf and 72 hpf with LC50 of 175 ± 10 mg/l. Computational analysis depicted the influential role of CuO nanoparticles on zebrafish embryo's he1a, sod1 and p53 functional expression through hydrophobic and hydrogen bond interaction with amino acid residues. Study demonstrated valuable information of cytotoxic impact which can be influential in further studies of their eco-toxicological effects.

Nickel(II)-induced nasal epithelial toxicity and oxidative mitochondrial damage

In probing the underlying mechanisms of nickel(II)-induced cytotoxicity on nasal epithelium, we investigated the effects of nickel(II) acetate on nasal epithelial RPMI-2650 cells. Nickel(II) elicited apoptosis, as signified by pyknotic and fragmented nuclei, increased caspase-3/7 activity, and an increase in annexin V binding, hypodiploid DNA, and Bax/Bcl-2 protein ratio. Nickel(II)-induced G2/M arrest was associated with up-regulation of p21(WAF1/CIP1) expression, decrease in phosphorylation at Thr(161) of Cdc2, and down-regulation of cyclin B1. Associated with these responses, ROS generation and mitochondrial depolarization increased in a nickel(II) concentration-dependent fashion. Pretreatment with N-acetylcysteine (NAC) attenuated these changes. p53 reporter gene assay and analyses of p53, Puma, Bax, and Bcl-2 protein levels indicated that NAC inhibited nickel(II)-induced activation of p53-mediated mitochondrial apoptotic pathway. Collectively, our study provides evidences that nickel(II) may induce oxidative damage on nasal epithelium in which antioxidant NAC protects cells against nickel(II)-induced apoptosis through the prevention of oxidative stress-mediated mitochondrial damage.

Pooling and Analysis of Published in Vitro Data: A Proof of Concept Study for the Grouping of Nanoparticles

The study aim was to test the applicability of pooling of nanomaterials-induced in vitro data for identifying the toxic capacity of specific (SiO₂, TiO₂, ZnO, CuO, CeO₂ and carbon nanotubes, [CNT]) nanoparticles (NP) and to test the usefulness for grouping purposes. Publication selection was based on specific criteria regarding experimental conditions. Two relevant biological endpoints were selected; generation of intracellular reactive oxygen species (ROS) and viability above 90%. The correlations of the ROS ratios with the NP parameters' size, concentration, and exposure time were analysed. The obtained data sets were then analysed with multiple regression analysis of variance (ANOVA) and the Tukey post-hoc test. The results show that this method is applicable for the selected metal oxide NP, but might need reconsideration and a larger data set for CNT. Several statistically significant correlations and results were obtained, thus validating the method. Furthermore, the relevance of the combination of ROS release with a cell viability test was shown. The data also show that it is advisable to compare ROS production of professional phagocytic with non-phagocytic cells. In conclusion, this is the first systematic analysis showing that pooling of available data into groups is a useful method for evaluation of data regarding NP induced toxicity in vitro.

Sulforaphane Protects the Liver against CdSe Quantum Dot-Induced Cytotoxicity

The potential cytotoxicity of cadmium selenide (CdSe) quantum dots (QDs) presents a barrier to their use in biomedical imaging or as diagnostic and therapeutic agents. Sulforaphane (SFN) is a chemoprotective compound derived from cruciferous vegetables which can up-regulate antioxidant enzymes and induce apoptosis and autophagy. This study reports the effects of SFN on CdSe QD-induced cytotoxicity in immortalised human hepatocytes and in the livers of mice. CdSe QDs induced dose-dependent cell death in hepatocytes with an IC₅₀ = 20.4 μM. Pre-treatment with SFN (5 μM) increased cell viability in response to CdSe QDs (20 μM) from 49.5 to 89.3%. SFN induced a pro-oxidant effect characterized by depletion of intracellular reduced glutathione during short term exposure (3–6 h), followed by up-regulation of antioxidant enzymes and glutathione levels at 24 h. SFN also caused Nrf2 translocation into the nucleus, up-regulation of antioxidant enzymes and autophagy. siRNA knockdown of Nrf2 suggests that the Nrf2 pathway plays a role in the protection against CdSe QD-induced cell death. Wortmannin inhibition of SFN-induced autophagy significantly suppressed the protective effect of SFN on CdSe QD-induced cell death. Moreover, the role of autophagy in SFN protection against CdSe QD-induced cell death was confirmed using mouse embryonic fibroblasts lacking ATG5. CdSe QDs caused significant liver damage in mice, and this was decreased by SFN treatment. In conclusion, SFN attenuated the cytotoxicity of CdSe QDs in both human hepatocytes and in the mouse liver, and this protection was associated with the induction of Nrf2 pathway and autophagy.

Activation of Erk and p53 regulates copper oxide nanoparticle-induced cytotoxicity in keratinocytes and fibroblasts

Copper oxide nanoparticles (CuONP) have attracted increasing attention due to their unique properties and have been extensively utilized in industrial and commercial applications. For example, their antimicrobial capability endows CuONP with applications in dressings and textiles against bacterial infections. Along with the wide applications, concerns about the possible effects of CuONP on humans are also increasing. It is crucial to evaluate the safety and impact of CuONP on humans, and especially the skin, prior to their practical application. The potential toxicity of CuONP to skin keratinocytes has been reported recently. However, the underlying mechanism of toxicity in skin cells has remained unclear. In the present work, we explored the possible mechanism of the cytotoxicity of CuONP in HaCaT human keratinocytes and mouse embryonic fibroblasts (MEF). CuONP exposure induced viability loss, migration inhibition, and G₂/M phase cycle arrest in both cell types. CuONP significantly induced mitogen-activated protein kinase (extracellular signal-regulated kinase [Erk], p38, and c-Jun N-terminal kinase [JNK]) activation in dose- and time-dependent manners. U0126 (an inhibitor of Erk), but not SB 239063 (an inhibitor of p38) or SP600125 (an inhibitor of JNK), enhanced CuONP-induced viability loss. CuONP also induced decreases in p53 and p-p53 levels in both cell types. Cyclic pifithrin-α, an inhibitor of p53 transcriptional activity, enhanced CuONP-induced viability loss. Nutlin-3α, a p53 stabilizer, prevented CuONP-induced viability loss in HaCaT cells, but not in MEF cells, due to the inherent toxicity of nutlin-3α to MEF. Moreover, the experiments on primary keratinocytes are in accordance with the conclusions acquired from HaCaT and MEF cells. These data demonstrate that the activation of Erk and p53 plays an important role in CuONP-induced cytotoxicity, and agents that preserve Erk or p53 activation may prevent CuONP-induced cytotoxicity.

Chip based single cell analysis for nanotoxicity assessment

Nanomaterials, because of their tunable properties and performances, have been utilized extensively in everyday life related consumable products and technology. On exposure, beyond the physiological range, nanomaterials cause health risks via affecting the function of organisms, genomic systems, and even the central nervous system. Thus, new analytical approaches for nanotoxicity assessment to verify the feasibility of nanomaterials for future use are in demand. The conventional analytical techniques, such as spectrophotometric assay-based techniques, usually require a lengthy and time-consuming process and often produce false positives, and often cannot be implemented at a single cell level measurement for studying cell behavior without interference from its surrounding environment. Hence, there is a demand for a precise, accurate, sensitive assessment for toxicity using single cells. Recently, due to the advantages of automation of fluids and minimization of human errors, the integration of a cell-on-a-chip (CoC) with a microfluidic system is in practice for nanotoxicity assessments. This review explains nanotoxicity and its assessment approaches with advantages/limitations and new approaches to overcome the confines of traditional techniques. Recent advances in nanotoxicity assessment using a CoC integrated with a microfluidic system are also discussed in this review, which may be of use for nanotoxicity assessment and diagnostics.

Mechanisms of nanotoxicity: generation of reactive oxygen species

Nanotechnology is a rapidly developing field in the 21^st century, and the commercial use of nanomaterials for novel applications is increasing exponentially. To date, the scientific basis for the cytotoxicity and genotoxicity of most manufactured nanomaterials are not understood. The mechanisms underlying the toxicity of nanomaterials have recently been studied intensively. An important mechanism of nanotoxicity is the generation of reactive oxygen species (ROS). Overproduction of ROS can induce oxidative stress, resulting in cells failing to maintain normal physiological redox-regulated functions. This in turn leads to DNA damage, unregulated cell signaling, change in cell motility, cytotoxicity, apoptosis, and cancer initiation. There are critical determinants that can affect the generation of ROS. These critical determinants, discussed briefly here, include: size, shape, particle surface, surface positive charges, surface-containing groups, particle dissolution, metal ion release from nanometals and nanometal oxides, UV light activation, aggregation, mode of interaction with cells, inflammation, and pH of the medium.

Dose-dependent genotoxicity of copper oxide nanoparticles stimulated by reactive oxygen species in human lung epithelial cells

Copper oxide nanoparticles (CuO NPs) are of great interest in nanoscience and nanotechnology because of their broad industrial and commercial applications. Therefore, toxicity of CuO NPs needs to be thoroughly understood. The aim of this study was to investigate the cytotoxicity, genotoxicity, and oxidative stress induced by CuO NPs in human lung epithelial (A549) cells. CuO NPs were synthesized by solvothermal method and the size of NPs measured under transmission electron microscopy (TEM) was found to be around 23 nm. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) and lactate dehydrogenase (LDH) assays showed that CuO NPs (5–15 µg/ml) exert cytotoxicity in A549 cells in a dose-dependent manner. Comet assay suggested concentration-dependent induction of DNA damage due to the exposure to CuO NPs. The comet tail moment was 27% at 15 µg/ml of CuO NPs, whereas it was 5% in control ( p < 0.05). The flow cytometry data revealed that CuO NPs induced micronuclei (MN) in A549 cells dose dependently. The frequency of MN was 25/103 cells at 15 µg/ml of CuO NPs, whereas it was 2/103 cells for control. CuO NPs were also found to induce oxidative stress in a concentration-dependent manner, which was indicated by induction of reactive oxygen species (ROS) and lipid peroxidation along with glutathione depletion. Moreover, MN induction and DNA damage were significantly correlated with ROS ( R2 = 0.937 for ROS vs. olive tail moment, and R2 = 0.944 for ROS vs. MN). Taken together, this study suggested that CuO NPs induce genotoxicity in A549 cells, which is likely to be mediated through ROS generation and oxidative stress.

Biosensing approaches for rapid genotoxicity and cytotoxicity assays upon nanomaterial exposure

The increased utilization of nanomaterials could affect human health and the environment due to increased exposure. Several mechanisms regarding the negative effects of nanomaterials have been proposed, one of the most discussed being oxidative stress. Many studies have shown that some metal oxide nanoparticles can enhance reactive oxygen species generation, inducing oxidative stress, DNA damage, and unregulated cell signaling, and eventually leading to changes in cell motility, apoptosis, and even carcinogenesis. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) is one of the predominant forms of oxidative DNA damage, and has therefore been widely used as a biomarker for oxidative stress and carcinogenesis. Ther are two major objectives to this study. Firstly, the development of a novel lateral flow immunoassay (LFIA) is presented to measure the concentration of 8-OHdG in cells and thus reveal the nanotoxicity on the genomic level. The feasibility of this new method is validated by comparison with two other established methods: Alamar Blue assay and a recently developed electrical impedance sensing (EIS) system on the level of cell proliferation/viability. Secondly, the toxicological effects of three metallic nanoparticles (CuO, CdO, and TiO2 ) are investigated and compared using these three methods with completely different mechanisms. The results show that there is a high variation among different nanoparticles concerning their ability to cause toxic effects. CuO nanoparticles are the most potent regarding cytotoxicity and DNA damage. CdO shows a fallen cell viability as well as DNA damage, however, to a lesser extent than CuO nanoparticles. TiO2 particles only cause very limited cytotoxicity, and there is no obvious increase in 8-OHdG levels. In conclusion, LFIA as well as the EIS system are useful methods for quantitative or qualitative nanotoxicity assessments with high sensitivity, specificity, speed of performance, and simplicity.

Evaluation of cytotoxicity of polypyrrole nanoparticles synthesized by oxidative polymerization

Polypyrrole (Ppy) is known as biocompatible material, which is used in some diverse biomedical applications and seeming to be a very promising for advanced biotechnological applications. In order to increase our understanding about biocompatibility of Ppy, in this study pure Ppy nanoparticles (Ppy-NPs) of fixed size and morphology were prepared by one-step oxidative polymerization and their cyto-compatibility was evaluated. The impact of different concentration of Ppy nanoparticles on primary mouse embryonic fibroblasts (MEF), mouse hepatoma cell line (MH-22A), and human T lymphocyte Jurkat cell line was investigated. Cell morphology, viability/proliferation after the treatment by Ppy nanoparticles was evaluated. Obtained results showed that Ppy nanoparticles at low concentrations are biocompatible, while at high concentrations they became cytotoxic for Jurkat, MEF and MH-22A cells, and it was found that cytotoxic effect is dose-dependent.

The neuroprotector kynurenic acid increases neuronal cell survival through neprilysin induction

Kynurenic acid (KYNA), one of the main product of the kynurenine pathway originating from tryptophan, is considered to be neuroprotective. Dysregulation of KYNA activity is thought to be involved in neurodegenerative diseases, the physiopathology of which evokes excitotoxicity, oxidative stress and/or protein aggregation. The neuroprotective effect of KYNA is generally attributed to its antagonistic action on NMDA receptors. However, this single target action appears insufficient to support KYNA beneficial effects against complex neurodegenerative processes including neuroinflammation, β-amyloid peptide (Aβ) toxicity and apoptosis. Novel insights are therefore required to elucidate KYNA neuroprotective mechanisms. Here, we combined cellular, biochemical, molecular and pharmacological approaches to demonstrate that low micromolar concentrations of KYNA strongly induce neprilysin (NEP) gene expression, protein level and enzymatic activity increase in human neuroblastoma SH-SY5Y cells. Furthermore, our studies revealed that KYNA exerts a protective effect on SH-SY5Y cells by increasing their viability through a mechanism independent from NMDA receptors. Interestingly, KYNA also induced NEP activity and neuroprotection in mouse cortical neuron cultures the viability of which was more promoted than SH-SY5Y cell survival under KYNA treatment. KYNA-evoked neuroprotection disappeared in the presence of thiorphan, an inhibitor of NEP activity. NEP is a well characterized metallopeptidase whose deregulation leads to cerebral Aβ accumulation and neuronal death in Alzheimer's disease. Therefore, our results suggest that a part of the neuroprotective role of KYNA may depend on its ability to induce the expression and/or activity of the amyloid-degrading enzyme NEP in nerve cells.

Zinc oxide nanoparticles selectively induce apoptosis in human cancer cells through reactive oxygen species

Background

Zinc oxide nanoparticles (ZnO NPs) have received much attention for their implications in cancer therapy. It has been reported that ZnO NPs induce selective killing of cancer cells. However, the underlying molecular mechanisms behind the anticancer response of ZnO NPs remain unclear.

Methods and results

We investigated the cytotoxicity of ZnO NPs against three types of cancer cells (human hepatocellular carcinoma HepG2, human lung adenocarcinoma A549, and human bronchial epithelial BEAS-2B) and two primary rat cells (astrocytes and hepatocytes). Results showed that ZnO NPs exert distinct effects on mammalian cell viability via killing of all three types of cancer cells while posing no impact on normal rat astrocytes and hepatocytes. The toxicity mechanisms of ZnO NPs were further investigated using human liver cancer HepG2 cells. Both the mRNA and protein levels of tumor suppressor gene p53 and apoptotic gene bax were upregulated while the antiapoptotic gene bcl-2 was downregulated in ZnO NP-treated HepG2 cells. ZnO NPs were also found to induce activity of caspase-3 enzyme, DNA fragmentation, reactive oxygen species generation, and oxidative stress in HepG2 cells.

Conclusion

Overall, our data demonstrated that ZnO NPs selectively induce apoptosis in cancer cells, which is likely to be mediated by reactive oxygen species via p53 pathway, through which most of the anticancer drugs trigger apoptosis. This study provides preliminary guidance for the development of liver cancer therapy using ZnO NPs.