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.     

Physiological effects of magnetite (Fe3O4) nanoparticles on perennial ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta) plants

Abstract

To date, knowledge gaps and associated uncertainties remain unaddressed on the effects of nanoparticles (NPs) on plants. This study was focused on revealing some of the physiological effects of magnetite (Fe₃O₄) NPs on perennial ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta cv. white cushaw) plants under hydroponic conditions. This study for the first time reports that Fe₃O₄ NPs often induced more oxidative stress than Fe₃O₄ bulk particles in the ryegrass and pumpkin roots and shoots as indicated by significantly increased: (i) superoxide dismutase and catalase enzyme activities, and (ii) lipid peroxidation. However, tested Fe₃O₄ NPs appear unable to be translocated in the ryegrass and pumpkin plants. This was supported by the following data: (i) No magnetization was detected in the shoots of either plant treated with 30, 100 and 500 mg l^?1 Fe₃O₄ NPs; (ii) Fe K-edge X-ray absorption spectroscopic study confirmed that the coordination environment of Fe in these plant shoots was similar to that of Fe-citrate complexes, but not to that of Fe₃O₄ NPs; and (iii) total Fe content in the ryegrass and pumpkin shoots treated with Fe₃O₄ NPs was not significantly increased compared to that in the control shoots.     

Assessment of thyroid endocrine system impairment and oxidative stress mediated by cobalt ferrite (CoFe2O4) nanoparticles in zebrafish larvae

Fascinating super paramagnetic uniqueness of iron oxide particles at nano‐scale level make them extremely useful in the state of the art therapies, equipments, and techniques. Cobalt ferrite (CoFe₂O₄) magnetic nanoparticles (MNPs) are extensively used in nano‐based medicine and electronics, results in extensive discharge and accumulation into the environment. However, very limited information is available for their endocrine disrupting potential in aquatic organisms. In this study, the thyroid endocrine disrupting ability of CoFe₂O₄ NPs in Zebrafish larvae for 168‐h post fertilization (hpf) was evaluated. The results showed the elevated amounts of T4 and T3 hormones by malformation of hypothalamus pituitary axis in zebrafish larvae. These elevated levels of whole body THs leads to delayed hatching, head and eye malformation, arrested development, and alterations in metabolism. The influence of THs disruption on ROS production and change in activities of catalase (CAT), mu‐glutathione s‐transferase (mu‐GST), and acid phosphatase (AP) were also studied. The production of significantly higher amounts of in vivo generation of ROS leads to membrane damage and oxidative stress. Presences of NPs and NPs agglomerates/aggregates were also the contributing factors in mechanical damaging the membranes and physiological structure of thyroid axis. The increased activities of CAT, mu‐GST, and AP confirmed the increased oxidative stress, possible DNA, and metabolic alterations, respectively. The excessive production of in vivo ROS leads to severe apoptosis in head, eye, and heart region confirming that malformation leads to malfunctioning of hypothalamus pituitary axis. ROS‐induced oxidative DNA damage by formation of 8‐OHdG DNA adducts elaborates the genotoxicity potential of CoFe₂O₄ NPs. This study will help us to better understand the risk and assessment of endocrine disrupting potential of nanoparticles. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 2068–2080, 2016.     

Fe3O4 nanoparticle redox system modulation via cell‐cycle progression and gene expression in human mesenchymal stem cells

The use of engineered nanoparticles (NPs) across multiple fields and applications has rapidly increased over the last decade owing to their unusual properties. However, there is an increased need in understanding their toxicological effect on human health. Particularly, iron oxide (Fe₃O₄) have been used in various sectors, including biomedical, food, and agriculture, but the current understanding of their impact on human health is inadequate. In this investigation, we assessed the toxic effect of Fe₃O₄ NPs on human mesenchymal stem cells (hMSCs) adopting cell viability, cellular morphological changes, mitochondrial transmembrane potential, and cell‐cycle progression assessment methodologies. Furthermore, the expression of oxidative stress, cell death, and cell‐cycle regulatory genes was assessed using quantitative polymerase chain reaction. The Fe₃O₄ NPs induced cytotoxicity and nuclear morphological changes in hMSCs by dose and time exposure. Cell‐cycle analysis indicated that Fe₃O₄ NPs altered the cell‐cycle progression through a decrease in the proportion of cells in the G₀–G₁ phase. The hMSC mitochondrial membrane potential loss increased with an increase in the concentration of Fe₃O₄ NPs exposure. The observed expression levels of the CYP1A, TNF3, TNFSF10, E2F1, and CCNC genes were significantly upregulated in hMSCs in response to Fe₃O₄ NPs exposure. Our findings suggest that Fe₃O₄ NPs caused metabolic stress through altered cell cycle, oxidative stress, and cell death regulatory gene expression in hMSCs. The results of this investigation revealed that Fe₃O₄ NPs exhibited moderate toxicity on hMSCs and that Fe₃O₄ NPs may have biomedical applications at low concentrations. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 901–912, 2016.     

Toxicity of antimony trioxide nanoparticles on human hematopoietic progenitor cells and comparison to cell lines

Nanoparticles (NPs) are materials with one dimension in the range of 1–100 nm. The toxicity of NPs remains widely unknown and still poses concerns, due to the peculiar characteristics of materials in the nano-size range. We analyze the toxicity of seven NPs (Fe₂O₃, Fe₃O₄, Sb₂O₃, Au, TiO₂, Co, and Ag) on primary cultures of human hematopoietic progenitor cells from the bone marrow of healthy donors with CFU assays, and show that antimony oxide (Sb₂O₃) NPs and cobalt (Co) NPs have a toxic effect, while the other NPs have no effect at the tested concentrations (5, 25 and 100 μg/ml). While Co NPs suspension is toxic to both erythroid and granulocytic–monocytic precursors, Sb₂O₃ NPs at 5 μg/ml are specifically toxic to erythroid colony development, suggesting a highly selective type of toxicity. With liquid culture assays we show that Sb₂O₃ NPs impair the proliferation of erythroid progenitors, while no toxic effect is observed when Sb₂O₃ NPs are added during erythroid differentiation. CFU assays and liquid culture assays on seven human cell lines of hematopoietic origin (K562, HL-60, CEM, CEM-R, Thp-1, Jurkat, and Molt-4) show that, contrary to what observed on primary cultures of bone marrow progenitors, Sb₂O₃ NPs have no toxic effect on proliferation of any of the cell lines, raising concerns about the use of immortalized cell lines for nanotoxicology tests.     

Phytotoxicity and biotransformation of La2O3 nanoparticles in a terrestrial plant cucumber (Cucumis sativus)

Abstract

With the increasing applications of metal-based nanoparticles in various commercial products, it is necessary to address their environmental fate and potential toxicity. In this work, we assessed the phytotoxicity of lanthanum oxide (La₂O₃) NPs to cucumber plants and determined its distribution and biotransformation in roots by TEM and EDS, as well as STXM and NEXAFS. LaCl₃ was also studied as a reference toxicant. La₂O₃ NPs and LaCl₃ were both transformed to needle-like LaPO₄ nanoclusters in the intercellular regions of the cucumber roots. In vitro experiments demonstrated that the dissolution of La₂O₃ NPs was significantly enhanced by acetic acid. Accordingly, we proposed that the dissolution of NPs at the root surface induced by the organic acids extruded from root cells played an important role in the phytotoxicity of La₂O₃ NPs. The reactions of active NPs at the nano-bio interface should be taken into account when studying the toxicity of dissolvable metal-based nanoparticles.     

In vitro evaluation of the toxicity and underlying molecular mechanisms of Janus Fe3O4‐TiO2 nanoparticles in human liver cells

Recent studies show that Janus Fe₃O₄‐TiO₂ nanoparticles (NPs) have potential applications as a multifunctional agent of magnetic resonance imaging (MRI) and photodynamic therapy (PDT) for the diagnosis and therapy of cancer. However, little work has been done on their biological effects. To evaluate the toxicity and underlying molecular mechanisms of Janus Fe₃O₄‐TiO₂ nanoparticles, an in vitro study using a human liver cell line HL‐7702 cells was conducted. For comparison, the Janus Fe₃O₄‐TiO₂ NPs parent material TiO₂ NPs was also evaluated. Results showed that both Fe₃O₄‐TiO₂ NPs and TiO₂ NPs decreased cell viability and ATP levels when applied in treatment, but increased malonaldehyde (MDA) and reactive oxygen species (ROS) generation. Mitochondria JC‐1 staining assay showed that mitochondrial membrane permeability injury occurred in both NPs treated cells. Cell viability analysis showed that TiO₂ NPs induced slightly higher cytotoxicity than Fe₃O₄‐TiO₂ NPs in HL7702 cells. Western blotting indicated that both TiO₂ NPs and Fe₃O₄‐TiO₂ NPs could induce apoptosis, inflammation, and carcinogenesis related signal protein alterations. Comparatively, Fe₃O₄‐TiO₂ NPs induced higher signal protein expressions than TiO₂ NPs under a high treatment dose. However, under a low dose (6.25 μg/cm²), neither NPs had any significant toxicity on HL7702 cells. In addition, our results suggest both Fe₃O₄‐TiO₂ NPs and TiO₂ NPs could induce oxidative stress and have a potential carcinogenetic effect in vitro. Further studies are needed to elaborate the detailed mechanisms of toxicity induced by a high dose of Fe₃O₄‐TiO₂ NPs.     

A comparative study on the in vitro cytotoxic responses of two mammalian cell types to fullerenes,carbon nanotubes and iron oxide nanoparticles

The present study was designed to evaluate and compare the time- and dose-dependent cellular response of human periodontal ligament fibroblasts (hPDLFs), and mouse dermal fibroblasts (mDFs) to three different types of nanoparticles (NPs); fullerenes (C₆₀), single walled carbon nanotubes (SWCNTs) and iron (II,III) oxide (Fe₃O₄) nanoparticles via in vitro toxicity methods, and impedance based biosensor system. NPs were characterized according to their morphology, structure, surface area, particle size distribution and zeta potential by using transmission electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller, dynamic light scattering and zeta sizer analyses. The Mössbauer spectroscopy was used in order to magnetically characterize the Fe₃O₄ NPs. The hPDLFs and mDFs were exposed to different concentrations of the NPs (0.1, 1, 10, 50 and 100?μg/mL) for predetermined time intervals (6, 24 and 48?h) under controlled conditions. Subsequently, NP exposed cells were tested for viability, membrane leakage and generation of intracellular reactive oxygen species. Additional to in vitro cytotoxicity assays, the cellular responses to selected NPs were determined in real time using an impedance based biosensor system. Taken together, information obtained from all experiments suggests that toxicity of the selected NPs is cell type, concentration and time dependent.     

One-step preparation,characterization, and anticancer potential of ZnFe2O4/RGO nanocomposites

Zinc ferrite nanoparticles (ZnFe₂O₄ NPs) have attracted extensive attention for their diverse applications including sensing, waste-water treatment, and biomedicine. The novelty of the present work is the fabrication of ZnFe₂O₄/RGO NCs by using a one-step hydrothermal process to assess the influence of RGO doping on the physicochemical properties and anticancer efficacy of ZnFe₂O₄ NPs. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy-dispersive X-ray(EDX), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), UV–vis spectroscopy, and Photoluminescence (PL) spectroscopy were employed to characterize prepared pure ZnFe₂O₄ NPs and ZnFe₂O₄/ RGO NCs. XRD results showed that the synthesized samples have high crystallinity. Furthermore, the average crystal sizes of ZnFe₂O₄ nanoparticles (NPs) and ZnFe₂O₄/RGO nanocomposites (NCs) were 51.08 nm and 54.36 nm, respectively. SEM images revealed that pure ZnFe₂O₄ NPs were spherical in shape with uniformly loaded on the surface of the RGO nanosheet. XPS and EDX analysis confirmed the elemental compositions of ZnFe₂O₄/RGO NCs. Elemental mapping of SEM shows that the elemental compositions (Zn, Fe, O, and C) were homogeneously distributed in ZnFe₂O₄/RGO NCs. The intensity of FT-IR spectra depicted that pure ZnFe₂O₄ NPs were successfully anchored into the RGO nanosheet. An optical study suggested that the band gap energy of ZnFe₂O₄/RGO NCs (1.61 eV) was lower than that of pure ZnFe₂O₄ NPs (1.96 eV). PL spectra indicated that the recombination rate of the ZnFe₂O₄/ RGO NCs was lower than ZnFe₂O₄ NPs. MTT assay was used to evaluate the anticancer performance of ZnFe₂O₄ /RGO NCs and pure ZnFe₂O₄NPs against human cancer cells. In vitro study indicates that ZnFe₂O₄ /RGO NCs have higher anticancer activity against human breast (MCF-7) and lung (A549) cancer cells as compared to pure form ZnFe₂O₄ NPs. This work suggests that RGO doping enhances the anticancer activity of ZnFe₂O₄NPs by tuning its optical behavior. This study warrants future research on potential therapeutic applications of these types of nanocomposites.     

Origin of the different phytotoxicity and biotransformation of cerium and lanthanum oxide nanoparticles in cucumber

Abstract

To investigate how the physicochemical properties of nanoparticles (NPs) affect their biological and toxicological effects, we evaluated the phytotoxicity of CeO₂ and La₂O₃ NPs to cucumber (Cucumis sativus) plants and tried to clarify the relation between physicochemical properties of NPs and their behaviors. CeO₂ NPs had no phytotoxicity to cucumber at all tested concentrations, while La₂O₃ NPs showed significant inhibition on root elongation (?≥?2?mg/L), shoot elongation (at 2000?mg/L), root biomass (?≥?2?mg/L), and shoot biomass (?≥?20?mg/L), as well as induced more reactive oxygen species and cell death in roots (2000?mg/L). The different distribution and speciation of Ce and La in plants were determined by synchrotron-based micro X-ray fluorescence microscopy and X-ray absorption spectroscopy. In the aerial parts, all of La was combined with phosphate or carboxylic group, while a fraction of Ce was changed to Ce(III)–carboxyl complexes, implying that La₂O₃ acted as its ionic form, while CeO₂ displayed the behavior of particles or particle–ion mixtures. The higher dissolution of La₂O₃ than CeO₂ NPs might be the reason for their significant difference in phytotoxicity and transporting behaviors in cucumbers. To our knowledge, this is the first detailed study of the relation between the level of dissolution of NPs and their behaviors in plant systems.     

Exposure characteristics of ferric oxide nanoparticles released during activities for manufacturing ferric oxide nanomaterials

Abstract

The exposure characteristics of Fe₂O₃ nanoparticles (NPs) released in a factory were investigated, as exposure data on this type of NP is absent. The nature of the particles was identified in terms of their concentrations [i.e. number concentration (NC_20–1000?nm), mass concentration (MC_{100–1000?nm}), surface area concentration (SAC_10–1000?nm)], size distribution, morphology and elemental composition. The relationships between different exposure metrics were determined through analyses of exposure ranking (ER), concentration ratios (CR), correlation coefficients and shapes of the particle concentration curves. Work activities such as powder screening, material feeding and packaging generated higher levels of NPs as compared to those of background particles (p?<?0.01). The airborne Fe₂O₃ NPs exhibited a unimodal size distribution and a spindle-like morphology and consisted predominantly of the elements O and Fe. Periodic and activity-related characteristics were noticed in the temporal variations in NC_20–1000?nm and SAC_10–1000?nm. The modal size of the Fe₂O₃ NPs remained relatively constant (ranging from 10 to 15?nm) during the working periods. The ER, CR values and the shapes of NC_20–1000?nm and SAC_10–1000?nm curves were similar; however, these were significantly different from those for MC_{100–1000?nm}. There was a high correlation between NC_20–1000?nm and SAC_10–1000?nm, and relatively lower correlations between the two and MC_{100–1000?nm}. These findings suggest that the work activities during the manufacturing processes generated high levels of primary Fe₂O₃ NPs. The particle concentrations exhibited periodicity and were activity dependent. The number and SACs were found to be much more relevant metrics for characterizing NPs than was the mass concentration.     

Toxicity of binary mixtures of Al2O3 and ZnO nanoparticles toward fibroblast and bronchial epithelium cells

ABSTRACT

The objective of this study was to examine the cytotoxic effects of binary mixtures of Al₂O₃ and ZnO NPs using mouse fibroblast cells (L929) and human bronchial epithelial cells (BEAS-2B) as biological test systems. The synergistic, additive, or antagonistic behavior of the binary mixture was also investigated. In toxicity experiments, cellular morphology, mitochondrial function (MTT assay), apoptosis, nuclear size and shape, clonogenic assays, and damage based upon oxidative stress parameters were assessed under control and NPs exposure conditions. Although Abbott modeling results provided no clear evidence of the binary mixture of Al₂O₃ and ZnO NPs exhibiting synergistic toxicity, some specific assays such as apoptosis, nuclear size and shape, clonogenic assay, activities of antioxidant enzymatic enzymes catalase, superoxide dismutase, and levels of glutathione resulted in enhanced toxicity for the mixtures with 1 and 1.75 toxic units (TU) toward both cell types. Data demonstrated that co-presence of Al₂O₃ and ZnO NPs in the same environment might lead to more realistic environmental conditions. Our findings indicate cytotoxicity of binary mixtures of Al₂O₃ and ZnO NPs produced greater effects compared to toxicity of either individual compound.     

In vitro toxicity screening of magnetite nanoparticles by applying mesenchymal stem cells derived from human umbilical cord lining

Despite the growing interest in nanoparticles (NPs), their toxicity has not yet been defined and the development of new strategies and predictive models are required. Human stem cells (SCs) offer a promising and innovative cell‐based model. Among SCs, mesenchymal SCs (MSCs) derived from cord lining membrane (CL) may represent a new species‐specific tool for establishing efficient platforms for primary screening and toxicity/safety testing of NPs. Superparamagnetic iron oxide NPs, including magnetite (Fe₃O₄NPs), have aroused great public health and scientific concerns despite their extensive uses. In this study, CL‐MSCs were characterized and applied for in vitro toxicity screening of Fe₃O₄NPs. Cytotoxicity, internalization/uptake, differentiation and proliferative capacity were evaluated after exposure to different Fe₃O₄NP concentrations. Data were compared with those obtained from bone marrow (BM)‐MSCs. We observed, at early passages (P3), that: (1) cytotoxicity occurred at 10 μg/mL in CL‐MSCs and 100 μg/mL in BM‐MSCs (no differences in toxicity, between CL‐ and BM‐MSCs, were observed at higher dosage, 100‐300 μg/mL); (2) cell density decrease and monolayer features loss were affected at ≥50 μg/mL in CL‐MSCs only; and (3) NP uptake was concentration‐dependent in both MSCs. After 100 μg/mL Fe₃O₄NP exposures, the capacity of proliferation was decreased (P5‐P9) in CL‐MSCs without morphology alteration. Moreover, a progressive decrease of intracellular Fe₃O₄NPs was observed over culture time. Antigen surface expression and multilineage differentiation were not influenced. These findings suggest that CL‐MSCs could be used as a reliable cell‐based model for Fe₃O₄NP toxicity screening evaluation and support the use of this approach for improving the confidence degree on the safety of NPs to predict health outcomes.     

Carcinogenic potential of metal nanoparticles in BALB/3T3 cell transformation assay

Metal‐based nanoparticles (NPs), are currently used in many application fields including consumer products, pharmaceuticals, and biomedical treatments. In spite to their wide applications, an in‐depth study of their potential toxic effects is still lacking. The aim of the present research was to investigate the potential initiator or promoter‐like activity of different metallic NPs such as gold, iron, cobalt, and cerium using the Balb/3T3 two‐stage transformation assay. The results indicated that all the selected metallic NPs, except for cobalt, when used as initiators did not induce any transformation in Balb/3T3 cell line. Moreover, Au and Fe₃O₄ NPs, when used in place of the tumor promoter treatment TPA, increased significantly the number of Foci/dish as compared to the MCA treatment alone. The number of Foci/dish was 2.6 for Au NPs and 2.13 for Fe₃O₄ ones, similar to those obtained by the positive control treatment (MCA + TPA), whereas 1.27 for MCA treatment alone. On the contrary, CeO₂ NPs did not show any difference in the number of Foci/dish, as compared to MCA alone, but it decreased the number of foci by 65% in comparison to the positive control (MCA + TPA). As expected, cobalt NPs showed an increased cytotoxicity and only a few surviving cells were found at the time of analysis showing a number of Foci/dish of 0.13. For the first time, our data clearly showed that Au and Fe₃O₄ NPs act as promoters in the two stage transformational assay, suggesting the importance to fully investigate the NPs carcinogenic potential with different models. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 509–519, 2016.     

Siderite (FeCO3) and magnetite (Fe3O4) overload-dependent pulmonary toxicity is determined by the poorly soluble particle not the iron content

The two poorly soluble iron containing solid aerosols of siderite (FeCO₃) and magnetite (Fe₃O₄) were compared in a 4-week inhalation study on rats at similar particle mass concentrations of approximately 30 or 100?mg/m³. The particle size distributions were essentially identical (MMAD ≈1.4 μm). The iron-based concentrations were 12 or 38 and 22 or 66?mg Fe/m³ for FeCO₃ and Fe₃O₄, respectively. Modeled and empirically determined iron lung burdens were compared with endpoints suggestive of pulmonary inflammation by determinations in bronchoalveolar lavage (BAL) and oxidative stress in lung tissue during a postexposure period of 3 months. The objective of study was to identify the most germane exposure metrics, that are the concentration of elemental iron (mg Fe/m³), total particle mass (mg PM/m³) or particle volume (μl PM/m³) and their associations with the effects observed. From this analysis it was apparent that the intensity of pulmonary inflammation was clearly dependent on the concentration of particle-mass or -volume and not of iron. Despite its lower iron content, the exposure to FeCO₃ caused a more pronounced and sustained inflammation as compared to Fe₃O₄. Similarly, borderline evidence of increased oxidative stress and inflammation occurred especially following exposure to FeCO₃ at moderate lung overload levels. The in situ analysis of 8-oxoguanine in epithelial cells of alveolar and bronchiolar regions supports the conclusion that both FeCO₃ and Fe₃O₄ particles are effectively endocytosed by macrophages as opposed to epithelial cells. Evidence of intracellular or nuclear sources of redox-active iron did not exist. In summary, this mechanistic study supports previous conclusions, namely that the repeated inhalation exposure of rats to highly respirable pigment-type iron oxides cause nonspecific pulmonary inflammation which shows a clear dependence on the particle volume-dependent lung overload rather than any increased dissolution and/or bioavailability of redox-active iron.     

Iron oxide nanoparticles mediated cytotoxicity via PI3K/AKT pathway: Role of quercetin

Recently Fe₂O₃ NPs (iron oxide nanoparticles) have been extensively used in medical imaging and in industry also. As a result, people are increasingly exposed day by day to those nanoparticles. The adverse effect of Fe₂O₃ NPs is not so significant at lower doses but at higher doses Fe₂O₃ NPs causes significant damage to cells. The present study investigates the cell signaling mechanism of Fe₂O₃ NPs induced oxidative stress and cytotoxicity in vitro using murine hepatocytes as the working model. In addition, the cytoprotective action of quercetin in this pathophysiology has also been investigated. Dose-dependent studies suggest that incubation of hepatocytes with 250 μg/ml Fe₂O₃ NPs for 4 h significantly decreased the cell viability and intra-cellular antioxidant ability. This study also showed that exposure to Fe₂O₃ NPs caused hepatocytes death via apoptotic pathway. Incubation of hepatocytes with quercetin (50 μmol/L) prior to 1 h of Fe₂O₃ NPs exposure protects the cells from the altering activities of antioxidant indices, cytotoxicity and apoptotic death. Results suggest that Fe₂O₃ NPs induced cellular damage and quercetin plays a protective role in Fe₂O₃ NPs induced cytotoxicity and apoptotic death.     

High inflammogenic potential of rare earth oxide nanoparticles: the New Hazardous Entity

Due to the exponential increase in the development and utilization of rare earth oxide nanoparticles (REO NPs) in various fields, the possibility of exposure in humans by inhalation has increased. However, there are little information about hazards of REO NPs and its mechanisms of toxicity. In this study, we evaluated the acute pulmonary inflammation using 10 REO NPs (Dy₂O₃, Er₂O₃, Eu₂O₃, Gd₂O₃ La₂O₃, Nd₂O₃, Pr₆O₁₁, Sm₂O₃, Tb₄O₇, and Y₂O₃) and four well-known toxic particles (CuO, NiO, ZnO, and DQ12). Minimum three doses per NP were instilled into the lungs of female Wistar rats at surface area dose metric and lung inflammation was evaluated at 24?h post-instillation by bronchoalveolar lavage fluid (BALF) analysis and histopathological observation. All types of REO NPs showed common pathological changes including mild to moderate infiltration of neutrophils and activated macrophages in the alveoli, peribronchial, and perivascular region. The inflammogenic potential evaluated by the number of granulocytes divided by the treated surface area dose showed all types of REO NPs has much higher inflammogenic potential than DQ12, ZnO, and NiO NPs. The correlation plot between the number of granulocytes and the potential for reactive oxygen species (ROS) generation showed a good correlation with exception of Pr₆O₁₁. The higher inflammogenic potential of REO NPs than that of well-known highly toxic particles imply that REO NPs need special attention for inhalation exposure and more studies are needed. In addition, the potential of ROS generation is one of the key factors producing lung inflammation by REO NPs.     

Specific targeting of cancer cells by multifunctional mitoxantrone-conjugated magnetic nanoparticles

Abstract

We report on the synthesis of bifunctional mitoxantrone (MTX)-grafted magnetic nanoparticles (MNPs) modified by dopamine-polyethylene glycol-folic acid (DPA-PEG-FA) for targeted imaging and therapy of cancer. MNPs (～7–10?nm) were synthesized using the thermal decomposition reaction of Fe(acac)₃. Bromoacetyl (BrAc) terminal polyethylene glycol dopamine (DPA-PEG-BrAc) was synthesized and treated with ethylene diamine to form bifunctional PEG moiety containing dopamine at one end and amino group at the other end (i.e. DPA-PEG-NH₂). It was then reacted with Fe₃O₄ nanoparticles (NPs) to form Fe₃O₄-DPA-PEG-NH₂ NPs. The activated folic acid (FA) was chemically coupled to Fe₃O₄-DPA-PEG-NH₂, forming Fe₃O₄-DPA-PEG-FA. MTX was then conjugated to Fe₃O₄-DPA-PEG-FA, forming Fe₃O₄-DPA-PEG-FA-MTX. Physicochemical characteristics of the engineered MNPs were determined. The particle size analysis and electron microscopy showed an average size of ～35?nm for Fe₃O₄-DPA-PEG-FA-MTX NPs with superparamagnetic behavior. FT-IR spectrophotometry analysis confirmed the conjugation of FA and MTX onto the MNPs. Fluorescence microscopy, cytotoxicity assay and flow cytometry analysis revealed that the engineered Fe₃O₄-DPA-PEG-FA-MTX NPs were able to specifically bind to and significantly inhibit the folate receptor (FR)-positive MCF-7 cells, but not the FR-negative A549 cells. Based upon these findings, we suggest the Fe₃O₄-DPA-PEG-FA-MTX NPs as an effective multifunctional-targeted nanomedicine toward simultaneous imaging and therapy of FR-positive cancers.     

Comparison of manganese oxide nanoparticles and manganese sulfate with regard to oxidative stress, uptake and apoptosis in alveolar epithelial cells

Due to their physicochemical characteristics, metal oxide nanoparticles (NPs) interact differently with cells compared to larger particles or soluble metals. Oxidative stress and cellular metal uptake were quantified in rat type II alveolar epithelial cells in culture exposed to three different NPs: manganese(II,III) oxide nanoparticles (Mn₃O₄-NPs), the soluble manganese sulfate (Mn-salt) at corresponding equivalent doses, titanium dioxide (TiO₂-NPs) and cerium dioxide nanoparticles (CeO₂-NPs). In the presence of reactive oxygen species an increased apoptosis rate was hypothesized. Oxidative stress was assessed by detection of fluorescently labeled reactive oxygen species and by measuring intracellular oxidized glutathione. Catalytic activity was determined by measuring catalyst-dependent oxidation of thiols (DTT-assay) in a cell free environment. Inductively coupled plasma mass spectrometry was used to quantify cellular metal uptake. Apoptosis rate was determined assessing the activity of caspase-3 and by fluorescence microscopic quantification of apoptotic nuclei. Reactive oxygen species were mainly generated in cells treated with Mn₃O₄-NPs. Only Mn₃O₄-NPs oxidized intracellular glutathione. Catalytic activity could be exclusively shown for Mn₃O₄-NPs. Cellular metal uptake was similar for all particles, whereas Mn-salt could hardly be detected within the cell. Apoptosis was induced by both, Mn₃O₄-NPs and Mn-salt. The combination of catalytic activity and capability of passing the cell membrane contributes to the toxicity of Mn₃O₄-NPs. Apoptosis of samples treated with Mn-salt is triggered by different, potentially extracellular mechanisms.