Engineered cobalt oxide nanoparticles readily enter cells

Magnetic nanoparticles (NPs) have great potential for applications not only as catalysts or energy storage devices, but also in biomedicine, as contrast enhancement agents for magnetic resonance imaging, or for drug delivery. The same characteristics that make cobalt-based NPs so attractive raise serious questions about their safety. In this context, we investigated Co₃O₄-NPs. Believing that the characterization of NPs is relevant for understanding their biological activity, we analyzed them by atomic force and electron microscopy to define size, shape, and aggregation. To clarify whether their biological effects could be due to a potential release of cobalt ions, we evaluated spontaneous dissolution in different media. To determine their potential toxicity to human cells, we measured cell viability and ROS formation in two human cell lines using CoCl₂ for comparison. Co₃O₄-NPs induced a concentration- and time-dependent impairment of cellular viability, although cobalt ions were more toxic. We also demonstrated that cobalt causes a rapid induction of ROS if supplied in the form of Co₃O₄-NPs rather than as ions. Moreover, we evaluated the cellular uptake of NPs. Interestingly, Co₃O₄-NPs are able to enter the cell very rapidly, remaining confined in vesicles inside the cytoplasm. They were found also inside the cell nuclei, though less frequently.     

In vitro intestinal toxicity of copper oxide nanoparticles in rat and human cell models

Abstract

Human oral exposure to copper oxide nanoparticles (NPs) may occur following ingestion, hand-to-mouth activity, or mucociliary transport following inhalation. This study assessed the cytotoxicity of Cupric (II) oxide (CuO) and Cu₂O-polyvinylpyrrolidone (PVP) coated NPs and copper ions in rat (intestine epithelial cells; IEC-6) and human intestinal cells, two- and three-dimensional models, respectively. The effect of pretreatment of CuO NPs with simulated gastrointestinal (GI) fluids on IEC-6 cell cytotoxicity was also investigated. Both dose- and time-dependent decreases in viability of rat and human cells with CuO and Cu₂O-PVP NPs and Cu²⁺ ions was observed. In the rat cells, CuO NPs had greater cytotoxicity. The rat cells were also more sensitive to CuO NPs than the human cells. Concentrations of H₂O₂ and glutathione increased and decreased, respectively, in IEC-6 cells after a 4-h exposure to CuO NPs, suggesting the formation of reactive oxygen species (ROS). These ROS may have damaged the mitochondrial membrane of the IEC-6 cells causing a depolarization, as a dose-related loss of a fluorescent mitochondrial marker was observed following a 4-h exposure to CuO NPs. Dissolution studies showed that Cu₂O-PVP NPs formed soluble Cu whereas CuO NPs essentially remained intact. For GI fluid-treated CuO NPs, there was a slight increase in cytotoxicity at low doses relative to non-treated NPs. In summary, copper oxide NPs were cytotoxic to rat and human intestinal cells in a dose- and time-dependent manner. The data suggests Cu₂O-PVP NPs are toxic due to their dissolution to Cu ions, whereas CuO NPs have inherent cytotoxicity, without dissolving to form Cu ions.     

Phosphate-enhanced cytotoxicity of zinc oxide nanoparticles and agglomerates

Zinc oxide (ZnO) nanoparticles (NPs) have been found to readily react with phosphate ions to form zinc phosphate (Zn₃(PO₄)₂) crystallites. Because phosphates are ubiquitous in physiological fluids as well as waste water streams, it is important to examine the potential effects that the formation of Zn₃(PO₄)₂ crystallites may have on cell viability. Thus, the cytotoxic response of NIH/3T3 fibroblast cells was assessed following 24 h of exposure to ZnO NPs suspended in media with and without the standard phosphate salt supplement. Both particle dosage and size have been shown to impact the cytotoxic effects of ZnO NPs, so doses ranging from 5 to 50 μg/mL were examined and agglomerate size effects were investigated by using the bioinert amphiphilic polymer polyvinylpyrrolidone (PVP) to generate water-soluble ZnO ranging from individually dispersed 4 nm NPs up to micron-sized agglomerates. Cell metabolic activity measures indicated that the presence of phosphate in the suspension media can led to significantly reduced cell viability at all agglomerate sizes and at lower ZnO dosages. In addition, a reduction in cell viability was observed when agglomerate size was decreased, but only in the phosphate-containing media. These metabolic activity results were reflected in separate measures of cell death via the lactate dehydrogenase assay. Our results suggest that, while higher doses of water-soluble ZnO NPs are cytotoxic, the presence of phosphates in the surrounding fluid can lead to significantly elevated levels of cell death at lower ZnO NP doses. Moreover, the extent of this death can potentially be modulated or offset by tuning the agglomerate size. These findings underscore the importance of understanding how nanoscale materials can interact with the components of surrounding fluids so that potential adverse effects of such interactions can be controlled.     

Acute exposure to ZnO nanoparticles induces autophagic immune cell death

Abstract

The increasing risk of incidental exposure to nanomaterials has led to mounting concerns regarding nanotoxicity. Zinc oxide nanoparticles (ZnO NPs) are produced in large quantities and have come under scrutiny due to their capacity to cause cytotoxicity in vitro and potential to cause harm in vivo. Recent evidence has indicated that ZnO NPs promote autophagy in cells; however, the signaling pathways and the role of ion release inducing toxicity remain unclear. In this study, we report that ZnO NPs are immunotoxic to primary and immortalized immune cells. Importantly, such immunotoxicity is observed in mice in vivo, since death of splenocytes is seen after intranasal exposure to ZnO NPs. We determined that ZnO NPs release free Zn²⁺ that can be taken up by immune cells, resulting in cell death. Inhibiting free Zn²⁺ ions in solution with EDTA or their uptake with CaCl₂ abrogates ZnO NP-induced cell death. ZnO NP-mediated immune cell death was associated with increased levels of intracellular reactive oxygen species (ROS). ZnO NP death was not due to apoptosis, necroptosis or pyroptosis. Exposure of immune cells to ZnO NPs resulted in autophagic death and increased levels of LC3A, an essential component of autophagic vacuoles. Accordingly, ZnO NP-mediated upregulation of LC3A and induction of immune cell death were inhibited by blocking autophagy and ROS production. We conclude that release of Zn²⁺ from ZnO NPs triggers the production of excessive intracellular ROS, resulting in autophagic death of immune cells. Our findings suggest that exposure to ZnO NPs has the potential to impact host immunity.     

Mechanistic insight into reactivity and (geno)toxicity of well-characterized nanoparticles of cobalt metal and oxides

An increasing use of cobalt (Co)-based nanoparticles (NPs) in different applications and exposures at occupational settings triggers the need for toxicity assessment. Improved understanding regarding the physiochemical characteristics of Co metal NPs and different oxides in combination with assessment of toxicity and mechanisms may facilitate decisions for grouping during risk assessment. The aim of this study was to gain mechanistic insights in the correlation between NP reactivity and toxicity of three different Co-based NPs (Co, CoO, and Co₃O₄) by using various tools for characterization, traditional toxicity assays, as well as six reporter cell lines (ToxTracker) for rapid detection of signaling pathways of relevance for carcinogenicity. The results showed cellular uptake of all NPs in lung cells and induction of DNA strand breaks and oxidative damage (comet assay) by Co and CoO NPs. In-depth studies on the ROS generation showed high reactivity of Co, lower for CoO, and no reactivity of Co₃O₄ NPs. The reactivity depended on the corrosion and transformation/dissolution properties of the particles and the media highlighting the role of the surface oxide and metal speciation as also confirmed by in silico modeling. By using ToxTracker, Co NPs were shown to be highly cytotoxic and induced reporters related to oxidative stress (Nrf2 signaling) and DNA strand breaks. Similar effects were observed for CoO NPs but at higher concentrations, whereas the Co₃O₄ NPs were inactive at all concentrations tested. In conclusion, our study suggests that Co and CoO NPs, but not Co₃O₄, may be grouped together for risk assessment.     

Cytotoxicity and apoptosis induced by silver nanoparticles in human liver HepG2 cells in different dispersion media

Silver nanoparticles (Ag NPs) have been widely used in medical and healthcare products owing to their unique antibacterial activities. However, their safety for humans and the environment has not yet been established. This study evaluated the cellular proliferation and apoptosis of Ag NPs suspended in different solvents using human liver HepG2 cells. The ionization of Ag NPs in different dispersion media [deionized water, phosphate‐buffered saline (PBS), saline and cell culture] was measured using an Ag ion selective electrode. The MTT assay was used to examine the cell proliferation activities. The effects of Ag NPs on cell cycle, induction of apoptosis, production of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were analyzed using flow cytometry. The degree of Ag NPs ionization differed with dispersion media, with the concentrations of silver ions in deionized water being the highest in all suspensions. Ag NPs could inhibit the viability of HepG2 cells in a time‐ and concentration‐dependent manner. Ag NPs (40, 80 and 160 µg ml^?1) exposure could cause cell‐cycle arrest in the G2/M phase, significantly increasing the apoptosis rate and ROS generation, and decreasing the MMP in HepG2 cells more sensitive to deionized water than in cell culture. These results suggested that the cellular toxicological mechanism of Ag NPs might be related to the oxidative stress of cells by the generation of ROS, leading to mitochondria injury and induction of apoptosis. It also implies that it is important to assess the physicochemical properties of NPs in the media where the biological toxicity tests are performed. Copyright © 2015 John Wiley & Sons, Ltd.     

Zinc sulfide nanoparticles selectively induce cytotoxic and genotoxic effects on leukemic cells: involvement of reactive oxygen species and tumor necrosis factor alpha

The aim of the present study was to develop zinc sulfide nanoparticles (ZnS NPs) and to study their cytotoxicity against the KG‐1A (human acute myeloid leukemia) cell line. ZnS NPs were synthesized using the pyrolytic method and characterized by X‐ray diffraction, dynamic light scattering, surface zeta potential, scanning electron microscopy and atomic force microscopy. Cell viability study and flow cytometric analysis confirmed the potent cytotoxic effects of ZnS NPs on cancer cells in a dose‐dependent fashion. Successful uptakes of ZnS NPs by leukemic cells were confirmed by phase contrast fluorescence microscopy. pH‐dependent dissolution of ZnS NPs was done using atomic absorption microscopy to understand the cell‐specific internalization of Zn⁺. This internalization of NPs facilitated the generation of excess reactive oxygen species (ROS), followed by tumor necrosis factor alpha (TNF‐α) secretion which caused severe DNA damage as observed in the comet assay and altered the mitochondrial membrane potential (MMP) in leukemic cells. Surprisingly ZnS NPs had no toxic effects on normal lymphocytes at doses up to 50 µg ml^–1. Pre‐treatment with ROS and TNF‐α inhibitor confirmed that these nanoparticles were able to kill leukemic cells by generating an excess amount of ROS and thereby initiated TNF‐α mediated apoptosis pathway. These findings clarify the mechanism with which ZnS NPs induced anticancer activities in vitro. To elicit its utilities and its application to cancer treatment in vivo is under investigation. Copyright © 2014 John Wiley & Sons, Ltd.     

In vitro comparative cytotoxicity study of aminated polystyrene,zinc oxide and silver nanoparticles on a cervical cancer cell line

Nanoparticles use in nano-biotechnology applications have increased significantly with Aminated polystyrene amine (AmPs NP), Zinc oxide (ZnO NP), and Silver (Ag NP) nanoparticles utilized in wide variety of consumer products. This has presented a number of concerns due to their increased exposure risks and associated toxicity on living systems. Changes in the structural and physicochemical properties of nanoparticles can lead to changes in biological activities. This study investigates, compares, and contrasts the potential toxicity of AmPs, ZnO and Ag NPs on an in vitro model (HeLa cells) and assesses the associated mechanism for their corresponding cytotoxicity relative to the surface material. It was noted that NPs exposure attributed to the reduction in cell viability and high-level induction of oxidative stress. All three test particles were noted to induce ROS to varying degrees which is irrespective of the attached surface group. Cell cycle analysis indicated a G2/M phase cell arrest, with the corresponding reduction in G0/G1 and S phase cells resulting in caspase-mediated apoptotic cell death. These findings suggest that all three NPs resulted in the decrease in cell viability, increase intracellular ROS production, induce cell cycle arrest at the G2/M phase and finally result in cell death by caspase-mediated apoptosis, which is irrespective of their differences in physiochemical properties and attached surface groups.     

Comparative study of ZnO and TiO2 nanoparticles: physicochemical characterisation and toxicological effects on human colon carcinoma cells

Abstract

Despite human gastrointestinal exposure to nanoparticles (NPs), data on NPs toxicity in intestinal cells are quite scanty. In this study we evaluated the toxicity induced by zinc oxide (ZnO) and titanium dioxide (TiO₂) NPs on Caco-2 cells. Only ZnO NPs produced significant cytotoxicity, evaluated by two different assays. The presence of foetal calf serum in culture medium significantly reduced ZnO NPs toxicity as well as ion leakage and NP-cell interaction. The two NPs increased the intracellular amount of reactive oxygen species (ROS) after 6 h treatment. However, only ZnO NPs increased ROS and induced IL-8 release both after 6 and 24 h. Experimental data indicate a main role of chemical composition and solubility in ZnO NPs toxicity. Moreover our results suggest a key role of oxidative stress in ZnO NPs cytotoxicity induction related both to ion leakage and to cell interaction with NPs in serum-free medium.     

Oligomeric proanthocyanidins alleviate hexabromocyclododecane-induced cytotoxicity in HepG2 cells through regulation on ROS formation and mitochondrial pathway

Hexabromocyclododecane (HBCD), a type of brominated flame retardants (BFR), has become ubiquitous organic contaminants in recent years. However, studies on HBCD toxicity and the related molecular mechanisms are so far limited. The objective of the present study was to investigate the effects of oligomeric proanthocyanidins (OPCs) on cytotoxicity induced by HBCD and the underlying molecular mechanisms. HepG2 cells were treated with HBCD and/or OPCs at different concentrations, and cell viability, cell apoptosis, reactive oxygen species (ROS) production, cellular Ca²⁺ level, mitochondrial membrane potential (ΔΨ), cytochrome C (Cyt-c) release, and nuclear factor-erythroid 2-related factor 2 (Nrf2) proteins expression were evaluated. Results showed that HBCD induced toxic effects in HepG2 cells in a concentration-dependent manner. HBCD at high concentrations (40 and 60 μM) caused a significant decrease of cell viability and led to elevated cell apoptosis ratio, intracellular Ca²⁺ level, cytoplasmic Cyt-c level, and ROS production, together with a loss of ΔΨ and mobilization of Nrf2. Pretreatment with OPCs effectively attenuated the cytotoxic effects and ROS production, as well as mitochondrial responses induced by HBCD. Thus, OPCs could alleviate cytotoxicity in HepG2 cells induced by HBCD through regulation on intracellular Ca²⁺ level and ROS formation in a mitochondrial pathway.     

Cytotoxicity,oxidative stress and inflammation induced by ZnO nanoparticles in endothelial cells: interaction with palmitate or lipopolysaccharide

Recent studies showed that ZnO nanoparticles (NPs) might induce the toxicity to human endothelial cells. However, little is known about the interaction between ZnO NPs and circulatory components, which is likely to occur when NPs enter the blood. In this study, we evaluated ZnO NP‐induced cytotoxicity, oxidative stress and inflammation in human umbilical vein endothelial cells (HUVECs), with the emphasis on the interaction with palmitate (PA) or lipopolysaccharide (LPS), because PA and LPS are normal components in human blood that increase in metabolic diseases. Overall, ZnO NPs induced cytotoxicity and intracellular reactive oxygen species (ROS) at a concentration of 32 μg ml⁻¹, but did not significantly affect the release of inflammatory cytokines or adhesion of THP‐1 monocytes to HUVECs. In addition, exposure to ZnO NPs dose‐dependently promoted intracellular Zn ions in HUVECs. PA and LPS have different effects. Two hundred μm PA significantly induced cytotoxicity and THP‐1 monocyte adhesion, but did not affect ROS or release of inflammatory cytokines. In contrast, 1 μg ml⁻¹ LPS significantly induced ROS, release of inflammatory cytokines and THP‐1 monocyte adhesion, but not cytotoxicity. The presence of ZnO NPs did not significantly affect the toxicity induced by PA or LPS. In addition, the accumulation of Zn ions after ZnO NP exposure was not significantly affected by the presence of PA or LPS. We concluded that there was no interaction between ZnO NPs and PA or LPS on toxicity to HUVECs in vitro . Copyright © 2016 John Wiley & Sons, Ltd.     

Cytotoxicity and proliferative capacity impairment induced on human brain cell cultures after short‐ and long‐term exposure to magnetite nanoparticles

Since magnetic iron oxide nanoparticles (IONP) as magnetite (Fe₃O₄NPs) have potential applications in life sciences, industrial fields and biomedical care, the risks for occupational, general population and patients rises correspondingly. Excessive IONP accumulation in central nervous system (CNS) cells can lead to a disruption of normal iron metabolism/homeostasis, which is a characteristic hallmark resembling that of several neurodegenerative disorders. Fe₃O₄NPs‐ versus Fe₃O₄ bulk‐induced toxic effects have been assessed in two human CNS cells namely astrocytes (D384) and neurons (SH‐SY5Y) after short‐term exposure (4–24‐48 h) to 1–100 μg ml⁻¹, and long‐term exposure to lower concentrations. Short‐term Fe₃O₄NPs induced significant concentration‐ and time‐dependent alterations of mitochondrial function in D384 (25–75% cell viability decrease): effects started at 25 μg ml⁻¹ after 4 h, and 1 μg ml⁻¹ after 48 h. SH‐SY5Y were less susceptible: cytotoxicity occurred after 48  h only with 35–45% mortality (10–100 μg ml⁻¹). Accordingly, a more marked intracellular iron accumulation was observed in astrocytes than neurons. Membrane integrity was unaltered in both CNS cell types. Lowering Fe₃O₄NP concentrations (0.05–10 μg ml⁻¹) and prolonging the exposure time (up to 10 days), D384 toxicity was again observed (colony number decrease at ≥0.05 μg ml⁻¹, morphology alterations and colony size reduction at ≥0.5 μg ml⁻¹). Effects on SH‐SY5Y appeared at the highest concentration only. Fe₃O₄ bulk was always remarkably toxic toward both cells. In summary, human cultured astrocytes were susceptible to both Fe₃O₄NP and bulk forms following short‐term and extended exposure to low concentrations, while neurons were more resistant to NPs. Cellular iron overload may trigger adverse responses by releasing iron ions (particularly in astrocytes) thus compromising the normal functions of CNS. Copyright © 2016 John Wiley & Sons, Ltd.     

In vitro cytotoxicity of hydrothermally synthesized ZnO nanoparticles on human periodontal ligament fibroblast and mouse dermal fibroblast cells

The use of metal oxide nanoparticles (NPs) in industrial applications has been expanding, as a consequence, risk of human exposure increases. In this study, the potential toxic effects of zinc oxide (ZnO) NPs on human periodontal ligament fibroblast cells (hPDLFs) and on mouse dermal fibroblast cells (mDFs) were evaluated in vitro. We synthesized ZnO NPs (particle size; 7–8 nm) by the hydrothermal method. Characterization assays were performed with atomic force microscopy, Braun–Emmet–Teller analysis, and dynamic light scattering. The hPDLFs and mDFs were incubated with the NPs with concentrations of 0.1, 1, 10, 50 and 100 μg/mL for 6, 24 and 48 h. Under the control and NP-exposed conditions, we have made different types of measurements for cell viability and morphology, membrane leakage and intracellular reactive oxygen species generation. Also, we monitored cell responses to ZnO NPs using an impedance measurement system in real-time. While the morphological changes were visualized using scanning electron microscopy, the subcellular localization of NPs was investigated by transmission electron microscopy. Results indicated that ZnO NPs have significant toxic effects on both of the primary fibroblastic cells at concentrations of ∼50–100 μg/mL. The cytotoxicity of ZnO NPs on fibroblasts depended on concentration and duration of exposure.     

Comparative study of cyto‐ and genotoxic potential with mechanistic insights of tungsten oxide nano‐ and microparticles in lung carcinoma cells

The exigency of semiconductor and super capacitor tungsten oxide nanoparticles (WO₃ NPs) is increasing in various sectors. However, limited information on their toxicity and biological interactions are available. Hence, we explored the underlying mechanisms of toxicity induced by WO₃ NPs and their microparticles (MPs) using different concentrations (0–300 μg ml^–1) in human lung carcinoma (A549) cells. The mean size of WO₃ NPs and MPs by transmission electron microscopy was 53.84 nm and 3.88 μm, respectively. WO₃ NPs induced reduction in cell viability, membrane damage and the degree of induction was size‐ and dose‐dependent. There was a significant increase in the percentage tail DNA and micronuclei formation at 200 and 300 μg ml^–1 after 24 hours of exposure. The DNA damage induced by WO₃ NPs could be attributed to increased oxidative stress and inflammation through reactive oxygen species generation, which correlated with the depletion of reduced glutathione content, catalase and an increase in malondialdehyde levels. Cellular uptake studies unveiled that both the particles were attached/surrounded to the cell membrane according to their size. In addition, NP inhibited the progression of the cell cycle in the G₂/M phase. Other studies such as caspase‐9 and ‐3 and Annexin‐V‐fluorescein isothiocyanate revealed that NPs induced intrinsic apoptotic cell death at 200 and 300 μg ml^–1 concentrations. However, in comparison to NPs, WO₃ MPs did not incite any toxic effects at the tested concentrations. Under these experimental conditions, the no‐observed‐significant‐effect level of WO₃ NPs was determined to be ≤200 μg ml^–1 in A549 cells.     

Investigation on cobalt‐oxide nanoparticles cyto‐genotoxicity and inflammatory response in two types of respiratory cells

The increasing use of cobalt oxide (Co₃O₄) nanoparticles (NPs) in several applications and the suggested genotoxic potential of Co‐oxide highlight the importance of evaluating Co₃O₄ NPs toxicity. Cyto‐genotoxic and inflammatory effects induced by Co₃O₄ NPs were investigated in human alveolar (A549), and bronchial (BEAS‐2B) cells exposed to 1–40 µg ml^–1. The physicochemical properties of tested NPs were analysed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Cytotoxicity was studied to analyze cell viability (WST1 test) and membrane damage (LDH assay), direct/oxidative DNA damage was assessed by the Formamido‐pyrimidine glycosylase (Fpg)‐modified comet assay and inflammation by interleukin (IL)‐6, IL‐8 and tumor necrosis factor‐alpha (TNF‐α) release (ELISA). In A549 cells, no cytotoxicity was found, whereas BEAS‐2B cells showed a viability reduction at 40 µg ml^–1 and early membrane damage at 1, 5 and 40 µg ml–1. In A549 cells, direct and oxidative DNA damage at 20 and 40 µg ml^–1 were detected without any effects on cytokine release. In BEAS‐2B cells, significant direct DNA damage at 40 µg ml^–1 and significant oxidative DNA damage with a peak at 5 µg ml^–1, that was associated with increased TNF‐α release at 1 µg ml^–1 after 2 h and increased IL‐8 release at 20 µg ml^–1 after 24 h, were detected. The findings show in the transformed alveolar cells no cytotoxicity and genotoxic/oxidative effects at 20 and 40 µg ml^–1. In normal bronchial cells, moderate cytotoxicity, direct DNA damage only at the highest concentration and significant oxidative‐inflammatory effects at lower concentrations were detected. The findings confirm the genotoxic‐oxidative potential of Co₃O₄ NPs and show greater sensitivity of BEAS‐2B cells to cytotoxic and oxidative‐inflammatory effects suggesting the use of different cell lines and multiple end‐points to elucidate Co₃O₄ NPs toxicity. Copyright © 2015 John Wiley & Sons, Ltd.     

Hepatotoxicity and liver injury induced by hydroxyapatite nanoparticles

As hydroxyapatite nanoparticles (HA NPs) are increasingly used in biomedical and biotechnological fields, risk assessment of HA NPs has attracted extensive attention. Nevertheless, little is known about the potential adverse effects of HA NPs on normal hepatocytes and the liver. In the present study, we conducted an in vitro study in which 80‐nm HA NPs were incubated with normal Buffalo rat liver (BRL) cells. By analyzing the changes in cell viability, apoptosis/necrosis and the mitogen‐activated protein kinase (MAPK) signaling pathway, we investigated the cytotoxicity and potential mechanism of HA NPs in hepatocytes. Furthermore, we used the serum hematology and histopathology examinations to explore the in vivo effects of HA NPs on the structure and function of the liver. Our results showed that exposure to HA NPs at a concentration above 200 µg ml^?1 decreased cell viability, increased levels of lactate dehydrogenase (LDH) leakage, induced apoptosis and necrosis, and triggered the MAPK signaling pathway in BRL cells in a dose‐dependent manner. Moreover, our in vivo study indicated that HA NPs increased the white blood cell count (WBC) and the levels of tumor necrosis factor‐α (TNF‐α), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the serum, caused inflammatory cell infiltration at the portal area in the liver, and induced hepatic oxidative stress with elevated levels of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). These data demonstrate that at certain concentrations, 80‐nm HA NPs cause hepatotoxicity and liver injury. Copyright © 2014 John Wiley & Sons, Ltd.     

In vitro mechanistic study towards a better understanding of ZnO nanoparticle toxicity

Abstract

ZnO nanoparticles (NPs) elicit significant adverse effects in various cell types, organisms and in the environment. The toxicity of nanoscale ZnO has often been ascribed to the release of zinc ions from the NPs but it is not yet understood to which extent these ions contribute to ZnO NP toxicity and what are the underlying mechanisms. Here, we take one step forward by demonstrating that ZnO-induced Jurkat cell death is largely an ionic effect involving the extracellular release of high amounts of Zn(II), their rapid uptake by the cells and the induction of a caspase-independent alternative apoptosis pathway that is independent of the formation of ROS. In addition, we identified novel coating strategies to reduce ZnO NP dissolution and subsequent adverse effects.     

Cytotoxic and inflammatory responses of TiO2 nanoparticles on human peripheral blood mononuclear cells

Titanium dioxide nanoparticles (TiO₂‐NPs) have been widely used in many applications. Owing to their nanoscale size, interactions between cells and NPs have been expansively investigated. With the health concerns raised regarding the adverse effects of these interactions, closer examination of whether TiO₂‐NPs can induce toxicity towards human cells is greatly needed. Therefore, in this study, we investigated the cytotoxicity of TiO₂‐NPs towards human blood cells (peripheral blood mononuclear cells [PBMCs]) in serum‐free medium, for which there is little information regarding the cytotoxic effects of TiO₂‐NPs. Our results provide evidence that PBMCs treated with TiO₂‐NPs (at concentrations ≥25 μg ml^?1) for 24 h significantly reduced cell viability and significantly increased production of toxic mediators such as reactive oxygen species and inflammatory response cytokines such as interleukin‐6 and tumor necrosis factor‐α (P < 0.05). Cell apoptosis induction also occurred at these concentrations. Significant expressions of cyclooxygenase‐2 and interleukin‐1β were also observed in PBMCs treated with TiO₂‐NPs at concentrations ≥125 μg ml^?1. Our data presented here clearly indicate that the concentration of TiO₂‐NPs (at size ~26.4 ± 1.2 nm) applied to human blood cells has a strong impact on cytotoxic induction. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of mesoporous silica nanoparticles on cell viability and markers of oxidative stress

Abstract

In the recent years, the use of mesoporous silica nanoparticles (MSNs) has been extended in biomedical fields such as cancer therapy, drug and gene delivery, biosensors, and enzyme immobilization. Although nanomaterials are currently being widely used in modern technology, there is a lack of information regarding to the health and environmental implications of manufactured nanomaterials. In the present study, the effects of MSNs and surface functionalized MSNs on cell viability, markers of oxidative damages (mainly intracellular reactive oxygen species (ROS) formation), and oxidative DNA damage were investigated in vitro in rat pheochromocytoma PC12 cells. Following exposure of these nanoparticles (1.95–1000?µg/mL) to PC12 cells for 12 and 24?h, no significant reduction of cell viability was observed compared with control. Moreover, ROS formation and oxidative DNA damage were not significantly changed by these nanoparticles even at high concentrations or prolong exposures. In conclusion, the results showed that neither MSNs nor functionalized MSNs exhibited any remarkable in vitro toxic properties in PC12 cells even at high concentration.     

Neuroprotective effect of edible brown alga Eisenia bicyclis on amyloid beta peptide-induced toxicity in PC12 cells

Amyloid beta peptide (A??) oligomers increase intracellular reactive oxygen species (ROS) and calcium cation (Ca²⁺) concentrations, which causes neuronal cell death in Alzheimer??s disease (AD). Thus, the use of neuroprotective agents with antioxidative activity might be effective in the treatment of AD. In the present study, the neuroprotective effects of the methanol extract from edible brown alga Eisenia bicyclis (Laminariaceae) and its solvent soluble fractions together with the isolated phlorotannins on A??-induced toxicity were assessed by cell viability, intracellular ROS, and Ca²⁺ levels in PC12 cells. The addition of the methanol extract as well as its ethyl acetate and n-butanol fractions of E. bicyclis markedly reversed the A??-induced toxicity. Among six phlorotannins, including phloroglucinol (1), dioxinodehydroeckol (2), eckol (3), phlorofucofuroeckol A (4), dieckol (5), and 7-phloroeckol (6), isolated from the most active ethyl acetate fraction, 3?C6 significantly decreased A??-induced cell death. Furthermore, these compounds also inhibited intracellular ROS generation and Ca²⁺ generation, indicating the neuroprotective effects may be mediated through reduced intracellular ROS and Ca²⁺ generation. Thus, the results of the present study imply that E. bicyclis and its active components attenuated the oxidative stress and reduced neuronal cell death, suggesting that it may be used as a dietary neuroprotective agent in AD.