Nanomaterials

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Open AccessEditorial

Challenges and Advances in Nanotoxicology

by Robert L. Tanguay

Nanomaterials 2014, 4(3), 766-767; https://doi.org/10.3390/nano4030766 - 22 Aug 2014

Cited by 4 | Viewed by 4795

Abstract

This Special Issue of Nanomaterials examines the potential for engineered nanomaterials to negatively impact biological systems and highlights some advances in evaluating key areas of their hazard potential. Nanomaterial science is evolving rapidly with the generation of more complex nanostructures with exciting potential [...] Read more.

This Special Issue of Nanomaterials examines the potential for engineered nanomaterials to negatively impact biological systems and highlights some advances in evaluating key areas of their hazard potential. Nanomaterial science is evolving rapidly with the generation of more complex nanostructures with exciting potential applications. Keeping modern toxicology abreast of this innovation to the point that it guides a safer nanotechnology presents an equally exciting and eminently worthwhile challenge. [...] Full article

(This article belongs to the Special Issue Nanotoxicology)

Research

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463 KiB

Open AccessArticle

Accumulation and Toxicity of Copper Oxide Engineered Nanoparticles in a Marine Mussel

by Shannon K. Hanna, Robert J. Miller and Hunter S. Lenihan

Nanomaterials 2014, 4(3), 535-547; https://doi.org/10.3390/nano4030535 - 27 Jun 2014

Cited by 42 | Viewed by 8125

Abstract

Cu is an essential trace element but can be highly toxic to aquatic organisms at elevated concentrations. Greater use of CuO engineered nanoparticles (ENPs) may lead to increased concentrations of CuO ENPs in aquatic environments causing potential ecological injury. We examined the toxicity [...] Read more.

Cu is an essential trace element but can be highly toxic to aquatic organisms at elevated concentrations. Greater use of CuO engineered nanoparticles (ENPs) may lead to increased concentrations of CuO ENPs in aquatic environments causing potential ecological injury. We examined the toxicity of CuO ENPs to marine mussels and the influence of mussels on the fate and transport of CuO ENPs. We exposed marine mussels to 1, 2, or 3 mg L⁻¹ CuO ENPs for four weeks, and measured clearance rate, rejection, excretion and accumulation of Cu, and mussel shell growth. Mussel clearance rate was 48% less, and growth was 68% less, in mussels exposed to 3 mg L⁻¹ than in control animals. Previous studies show 100% mortality at 1 mg Cu L⁻¹, suggesting that CuO ENPs are much less toxic than ionic Cu, probably due to the slow dissolution rate of the ENPs. Mussels rejected and excreted CuO ENPs in biodeposits containing as much as 110 mg Cu g⁻¹, suggesting the potential for magnification in sediments. Mussels exposed to 3 mg L⁻¹ CuO ENPs accumulated 79.14 ± 12.46 µg Cu g⁻¹ dry weight, which was 60 times more Cu than in control animals. Our results suggest that mussels have the potential to influence the fate and transport of CuO ENPs and potentially cause magnification of CuO ENPs in mussel bed communities, creating a significant source of Cu to marine benthos. Full article

(This article belongs to the Special Issue Nanotoxicology)

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Feeding rate of mussels exposed to CuO engineered nanoparticles (ENPs). Mean feeding rate for mussels exposed to CuO ENPs for four weeks. Feeding rate decreased with increasing CuO ENP concentration (ordinary least squares (OLS): Feeding = 1.99 × 10−2 − 3.1 × 10−3 (Concentration) − 8 × 10−4 (Time), r2 = 0.37). Error bars are one standard error of the mean. Full article ">Figure 2
Excretion of Cu in mussels exposed to CuO ENPs. Mean Cu concentration in biodeposits collected from mussels exposed to CuO ENPs for four weeks. Cu concentration in biodeposits increased with increasing CuO ENP concentration (OLS: Excretion = 0.83 + 27.48 (Concentration) + 1.47 (Time), r2 = 0.85). Error bars are one standard error of the mean. Full article ">Figure 3
Bioaccumulation of Cu in mussels exposed to CuO ENPs. Mean Cu concentration in (A) tissue and (B) gill of mussels exposed to CuO ENPs for four weeks. The impact of CuO ENPs on Cu concentration in tissue and gill depended on exposure time (OLS: Tissue Cu = 0.78 − 4.31 (Concentration) + 3.26 (Time) + 5.72 (Concentration × Time), r2 = 0.72; OLS: Gill Cu = −17.01 + 3.17 (Concentration) + 9.61 (Time) + 9.15 (Concentration × Time), r2 = 0.74). Error bars are standard error of the mean. Full article ">Figure 4
Growth rate of mussels exposed to CuO ENPs. Mean growth rate for mussels in the control group and those exposed to CuO ENPs for four weeks. The impact of CuO ENPs on growth rate depended on exposure time (OLS: Growth = 3.16 × 10−2 + 1.39 × 10−2 (Concentration) + 1.03 × 10−2 (Time) − 6.8 × 10−3 (Concentration × Time), r2 = 0.20). Error bars are one standard error of the mean. Full article ">

2557 KiB

Open AccessArticle

Reducing X-Ray Induced Oxidative Damages in Fibroblasts with Graphene Oxide

by Yong Qiao, Peipei Zhang, Chaoming Wang, Liyuan Ma and Ming Su

Nanomaterials 2014, 4(2), 522-534; https://doi.org/10.3390/nano4020522 - 24 Jun 2014

Cited by 41 | Viewed by 7562

Abstract

A major issue of X-ray radiation therapy is that normal cells can be damaged, limiting the amount of X-rays that can be safely delivered to a tumor. This paper describes a new method based on graphene oxide (GO) to protect normal cells from [...] Read more.

A major issue of X-ray radiation therapy is that normal cells can be damaged, limiting the amount of X-rays that can be safely delivered to a tumor. This paper describes a new method based on graphene oxide (GO) to protect normal cells from oxidative damage by removing free radicals generated by X-ray radiation using grapheme oxide (GO). A variety of techniques such as cytotoxicity, genotoxicity, oxidative assay, apoptosis, γ-H2AX expression, and micro-nucleus assay have been used to assess the protective effect of GO in cultured fibroblast cells. It is found that although GO at higher concentration (100 and 500 µg/mL) can cause cell death and DNA damage, it can effectively remove oxygen free radicals at a lower concentration of 10 µg/mL. The level of DNA damage and cell death is reduced by 48%, and 39%, respectively. Thus, low concentration GO can be used as an effective radio-protective agent in occupational and therapeutic settings. Full article

(This article belongs to the Special Issue Nanotoxicology)

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Open AccessArticle

Biological Effects of Clinically Relevant CoCr Nanoparticles in the Dura Mater: An Organ Culture Study

by Iraklis Papageorgiou, Thomas Abberton, Martin Fuller, Joanne L. Tipper, John Fisher and Eileen Ingham

Nanomaterials 2014, 4(2), 485-504; https://doi.org/10.3390/nano4020485 - 16 Jun 2014

Cited by 10 | Viewed by 6729

Abstract

Medical interventions for the treatment of spinal disc degeneration include total disc replacement and fusion devices. There are, however, concerns regarding the generation of wear particles by these devices, the majority of which are in the nanometre sized range with the potential to [...] Read more.

Medical interventions for the treatment of spinal disc degeneration include total disc replacement and fusion devices. There are, however, concerns regarding the generation of wear particles by these devices, the majority of which are in the nanometre sized range with the potential to cause adverse biological effects in the surrounding tissues. The aims of this study were to develop an organ culture model of the porcine dura mater and to investigate the biological effects of CoCr nanoparticles in this model. A range of histological techniques were used to analyse the structure of the tissue in the organ culture. The biological effects of the CoCr wear particles and the subsequent structural changes were assessed using tissue viability assays, cytokine assays, histology, immunohistochemistry, and TEM imaging. The physiological structure of the dura mater remained unchanged during the seven days of in vitro culture. There was no significant loss of cell viability. After exposure of the organ culture to CoCr nanoparticles, there was significant loosening of the epithelial layer, as well as the underlying collagen matrix. TEM imaging confirmed these structural alterations. These structural alterations were attributed to the production of MMP-1, -3, -9, -13, and TIMP-1. ELISA analysis revealed that there was significant release of cytokines including IL-8, IL-6, TNF-α, ECP and also the matrix protein, tenascin-C. This study suggested that CoCr nanoparticles did not cause cytotoxicity in the dura mater but they caused significant alterations to its structural integrity that could lead to significant secondary effects due to nanoparticle penetration, such as inflammation to the local neural tissue. Full article

(This article belongs to the Special Issue Nanotoxicology)

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Graphical abstract

Graphical abstract
Full article ">Figure 1
Images of histological sections of the isolated porcine dura-mater tissue at Day 0 (A) and after seven days in organ culture (B) stained with H&E. Immunohistochemical staining of the porcine dura mater with antibodies to fibronectin (C,D), collagen I (F,G), collagen II (I,J) at Day 0 and Day 7 respectively. Isotypes controls for fibronectin (E), collagen I (H) and collagen II (K) antibodies. Tissue viability over a period of 7 days in organ culture as determined by MTT assay (L). Results are presented as OD at 570 nm per mg of wet weight of tissue. Data is presented as the mean (n = 3) ± 95% confidence limits. Data were analysed by one-way analysis of variance and individual differences between group means determined by the T-method. * indicates significant difference (* p < 0.05). Full article ">Figure 2
(A) Representative image of cobalt-chrome nanoparticles that were generated using a pin-on-plate tribometer. Images were captured by FEGSEM; (B) Size distribution of cobalt-chrome nanoparticles. The size distribution of the cobalt-chrome nanoparticles was determined from SEM images taken from different locations on the filter membrane and analysed using Image Pro-Plus imaging software; (C) Effects of CoCr nanoparticles on the viability of dura-mater at 0 and 7 days of culture. Porcine dura mater tissue was cultured in the absence (control) and presence of CoCr nanoparticles at an estimated dose of 5 and 50 µm3 per epithelial cell and viability determined by the MTT assay. Data are expressed as the mean (n = 3) ± 95% confidence limits. The data were analysed by ANOVA which revealed no significant variation between control and CoCr-treated tissues at day 0 or day 7. Images of dura mater tissue exposed to cobalt-chrome nanoparticles at an estimated dosage of 0 (D), 5 (E) and 50 (F) µm3 per epithelial cell for a period of 7 days and stained with H&E. Tissues sections shown are orientated so that the outer epithelial layer is closest to the top of the section. Full article ">Figure 3
TEM images across the dura mater tissue that was exposed to CoCr nanoparticlesfor a period of seven days. (A–C) Images of the control dura mater from the epithelial region (A), inner collagen region (B) and the basal side of the dura mater close to arachnoid mater (C); (D–F) Images of the dura mater exposed to an estimated dose of 5 µm3 of CoCr particles per epithelial cell, from the epithelial region (D), inner collagen region (E), and the basal side of the dura mater close to arachnoid mater (F); (G–I) Images of the dura mater exposed to an estimated dose of 50 µm3 of CoCr particles per epithelial cell, from the epithelial region (G), inner collagen region (H), and the basal side of the dura mater close to arachnoid mater (I). Single continuous black arrows indicate the dural epithelial cells. Single dotted black arrow indicated the dural fibroblast cells. Black circles indicated disruption of the collagen layer. Full article ">Figure 4
Pattern of cytokine and other mediator release during the exposure of porcine dura mater to CoCr nanoparticles for a period of 0–7 days. The dura mater organ culture was exposed to estimated doses of 0 (control), 5 and 50 µm3 of CoCr nanoparticles per epithelial cell. The factors that were investigated were IL-8 (A), IL-1β (B), TNF-α (C), IL-6 (D), LBT-4 (leukotriene B4) (E), IL-33 (F), ECP (eosinophil chemotactic protein, eotaxin, CCL-11) (G), and tenascin C (H). Data is expressed as the mean (n = 3) ±95% confidence limits. Data were analysed by one-way analysis of variance and individual differences between group means determined by the T-method. * indicates significantly difference between control and CoCr-treated tissue (* p < 0.05). Full article ">Figure 5
Images of dura mater exposed for seven days to CoCr nanoparticles and stained for the presence of matrix metalloproteinases and TIMP-1 by immunhistochemistry. Images of section of control dura mater tissue (A,D,G,J,M), dura mater exposed to an estimated dose of 5 µm3 CoCr nanoparticles per epithelial cell (B,E,H,K,N) and dura mater exposed to an estimated dose of 50 µm3 CoCr nanoparticles per epithelial cell (C,F,I,L,O). The tissues were stained for MMP-1 (A–C), MMP-3 (D–F), MMP-9 (G–I), MMP-13 (J–L), TIMP-1 (M–O). Full article ">

4197 KiB

Open AccessArticle

Assessment of the Aerosol Generation and Toxicity of Carbon Nanotubes

by Patrick T. O'Shaughnessy, Andrea Adamcakova-Dodd, Ralph Altmaier and Peter S. Thorne

Nanomaterials 2014, 4(2), 439-453; https://doi.org/10.3390/nano4020439 - 12 Jun 2014

Cited by 9 | Viewed by 6899

Abstract

Current interest in the pulmonary toxicity of carbon nanotubes (CNTs) has resulted in a need for an aerosol generation system that is capable of consistently producing a CNT aerosol at a desired concentration level. This two-part study was designed to: (1) assess the [...] Read more.

Current interest in the pulmonary toxicity of carbon nanotubes (CNTs) has resulted in a need for an aerosol generation system that is capable of consistently producing a CNT aerosol at a desired concentration level. This two-part study was designed to: (1) assess the properties of a commercially-available aerosol generator when producing an aerosol from a purchased powder supply of double-walled carbon nanotubes (DWCNTs); and (2) assess the pulmonary sub-acute toxicity of DWCNTs in a murine model during a 5-day (4 h/day) whole-body exposure. The aerosol generator, consisting of a novel dustfeed mechanism and venturi ejector was determined to be capable of producing a DWCNT consistently over a 4 h exposure period at an average level of 10.8 mg/m³. The count median diameter was 121 nm with a geometric standard deviation of 2.04. The estimated deposited dose was 32 µg/mouse. The total number of cells in bronchoalveolar lavage (BAL) fluid was significantly (p < 0.01) increased in exposed mice compared to controls. Similarly, macrophages in BAL fluid were significantly elevated in exposed mice, but not neutrophils. All animals exposed to CNT and euthanized immediately after exposure had changes in the lung tissues showing acute inflammation and injury; however these pathological changes resolved two weeks after the exposure. Full article

(This article belongs to the Special Issue Nanotoxicology)

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1015 KiB

Open AccessArticle

The Impact of Surface Ligands and Synthesis Method on the Toxicity of Glutathione-Coated Gold Nanoparticles

by Bryan Harper, Federico Sinche, Rosina Ho Wu, Meenambika Gowrishankar, Grant Marquart, Marilyn Mackiewicz and Stacey L. Harper

Nanomaterials 2014, 4(2), 355-371; https://doi.org/10.3390/nano4020355 - 12 May 2014

Cited by 43 | Viewed by 12103

Abstract

Gold nanoparticles (AuNPs) are increasingly used in biomedical applications, hence understanding the processes that affect their biocompatibility and stability are of significant interest. In this study, we assessed the stability of peptide-capped AuNPs and used the embryonic zebrafish (Danio rerio) as [...] Read more.

Gold nanoparticles (AuNPs) are increasingly used in biomedical applications, hence understanding the processes that affect their biocompatibility and stability are of significant interest. In this study, we assessed the stability of peptide-capped AuNPs and used the embryonic zebrafish (Danio rerio) as a vertebrate system to investigate the impact of synthesis method and purity on their biocompatibility. Using glutathione (GSH) as a stabilizer, Au-GSH nanoparticles with identical core sizes were terminally modified with Tryptophan (Trp), Histidine (His) or Methionine (Met) amino acids and purified by either dialysis or ultracentrifugation. Au-GSH-(Trp)₂ purified by dialysis elicited significant morbidity and mortality at 200 µg/mL, Au-GSH-(His)₂ induced morbidity and mortality after purification by either method at 20 and 200 µg/mL, and Au-GSH-(Met)₂ caused only sublethal responses at 200 µg/mL. Overall, toxicity was significantly reduced and ligand structure was improved by implementing ultracentrifugation purifications at several stages during the multi-step synthesis and surface modification of Au-GSH nanoparticles. When carefully synthesized at high purity, peptide-functionalized AuNPs showed high biocompatibility in biological systems. Full article

(This article belongs to the Special Issue Nanotoxicology)

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Thin layer chromatography (TLC) determination of Au-GSH-(Met)2-U2 purity after ultracentrifugation. (A) Rf values for compounds listed on the TLC; (B) TLC plate of Au-GSH-(Met)2-U2: Lane A before purification, Lane B after purification by ultracentrifugation, and Lane C of free Met ligand in butanol/acetic acid/H2O (12:3:5) solvent system. Full article ">Figure 2
Representative 1H NMR spectra of (A) unpurified and (B) purified Au-GSH-(Trp)2-U2 nanoparticles in H2O at 25 °C. Full article ">Figure 3
Survival rates for embryonic zebrafish exposed to varying concentrations of Au-GSH-(X)2 (X = Trp, His, and Met) nanoparticles. Survival measured at 120 hpf for AuNPs with (A) His; (B) Trp; (C) Met. Results are presented as mean ± SEM. Asterisks indicate significant differences from control (untreated, concentration = 0) embryos (p ≤ 0.05, n = 48). Full article ">Figure 4
Incidence of sublethal effects in zebrafish embryos after 5 days of exposure to 200 µg/mL Au-GSH nanoparticles conjugated with (A) His; (B) Trp; or (C) Met. Data on malformations are presented as mean ± SEM (n = 48). Asterisk indicates significant difference exists in the percent incidence vs. control (untreated) embryos (p ≤ 0.05, n = 48). Full article ">Figure 5
Uptake of AuNPs containing (A) Au-GSH-(His)2-U1 or (B) Au-GSH-(Trp)2-U1, both purified by ultracentrifugation as measured by INAA in zebrafish at 24 and 120 hpf. Data are presented as mean ± STDV of three independent samples (n = 3). Asterisk indicates significant difference exists in gold content compared to untreated embryos (p ≤ 0.05, n = 48). Full article ">

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Open AccessArticle

Reproductive Toxicity and Life History Study of Silver Nanoparticle Effect, Uptake and Transport in Arabidopsis thaliana

by Jane Geisler-Lee, Marjorie Brooks, Jacob R. Gerfen, Qiang Wang, Christin Fotis, Anthony Sparer, Xingmao Ma, R. Howard Berg and Matt Geisler

Nanomaterials 2014, 4(2), 301-318; https://doi.org/10.3390/nano4020301 - 22 Apr 2014

Cited by 109 | Viewed by 11198

Abstract

Concerns about nanotechnology have prompted studies on how the release of these engineered nanoparticles impact our environment. Herein, the impact of 20 nm silver nanoparticles (AgNPs) on the life history traits of Arabidopsis thaliana was studied in both above- and below-ground parts, at [...] Read more.

Concerns about nanotechnology have prompted studies on how the release of these engineered nanoparticles impact our environment. Herein, the impact of 20 nm silver nanoparticles (AgNPs) on the life history traits of Arabidopsis thaliana was studied in both above- and below-ground parts, at macroscopic and microscopic scales. Both gross phenotypes (in contrast to microscopic phenotypes) and routes of transport and accumulation were investigated from roots to shoots. Wild type Arabidopsis growing in soil, regularly irrigated with 75 μg/L of AgNPs, did not show any obvious morphological change. However, their vegetative development was prolonged by two to three days and their reproductive growth shortened by three to four days. In addition, the germination rates of offspring decreased drastically over three generations. These findings confirmed that AgNPs induce abiotic stress and cause reproductive toxicity in Arabidopsis. To trace transport of AgNPs, this study also included an Arabidopsis reporter line genetically transformed with a green fluorescent protein and grown in an optical transparent medium with 75 μg/L AgNPs. AgNPs followed three routes: (1) At seven days after planting (DAP) at S1.0 (stages defined by Boyes et al. 2001 [41]), AgNPs attached to the surface of primary roots and then entered their root tips; (2) At 14 DAP at S1.04, as primary roots grew longer, AgNPs gradually moved into roots and entered new lateral root primordia and root hairs; (3) At 17 DAP at S1.06 when the Arabidopsis root system had developed multiple lateral roots, AgNPs were present in vascular tissue and throughout the whole plant from root to shoot. In some cases, if cotyledons of the Arabidopsis seedlings were immersed in melted transparent medium, then AgNPs were taken up by and accumulated in stomatal guard cells. These findings in Arabidopsis are the first to document specific routes and rates of AgNP uptake in vivo and in situ. Full article

(This article belongs to the Special Issue Nanotoxicology)

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Graphical abstract

Graphical abstract
Full article ">Figure 1
Study of life history traits of Arabidopsis plants irrigated with ddH2O or with AgNPs. (A,B) Morphology of Arabidopsis rosette leaves growing in potted soil. (A) Control plants irrigated with ddH2O; (B) treated plants with 75 μg/L of 20 nm AgNPs. (A) and (B) were at S3.50. (A) and (B) showed no distinct and visual differences. (C) Growth of aboveground vegetative parts of control and AgNP-treated within 42 days after planting (DAP). (D) Chronological progression of control, AgNPs-treated (both 75 and 300 μg/L) and AgNO3-treated (4.25 and 17 μg/L) plants from sowing to S6.90. Full article ">Figure 2
Reproductive nanotoxicity of AgNP and AgNO3 in Arabidopsis. This showed 20 nm AgNPs affected seed germination; it also showed stronger toxicity of AgNPs than that of AgNO3 on germination in E1 generation. Different letters indicate significantly different. Full article ">Figure 3
Transport of AgNPs in Arabidopsis ER::GFP plants. Seedlings of 14 (B,E) and 17 (A,C,D,F) days after planting (DAP) were examined under a Zeiss LSM 510 confocal microscope. (A,C) came from root sections of maturation region; (D–F) came from cotyledon. (A) and (D) are control; (B,C) and (E,F) are AgNPs-treated. Green color was intrinsic GFP; red color was Ag0 light scattering. At 14 DAP, AgNPs accumulated mainly in root hair cells and surface of roots (B). By 17 DAP, AgNPs already entered vascular tissue, both phloem (white arrowhead) and xylem (black arrowhead), of the roots and could be bulk transported through vascular tissue. Upon germination, some condensed media might have touched cotyledons. At 14 DAP, AgNPs could be observed in the pores of stomata (yellow arrows in E). By 17 DAP, not only the pores of stomata but also the stomata themselves (yellow arrows in F) showed AgNP accumulation. The uneven surface of pavement cells [<a href="#B56-nanomaterials-04-00301" class="html-bibr">56</a>] showed AgNP accumulated on the grooves (white arrowhead) between pavement cells (orange arrow). Scale bar = 0.2 μm. Full article ">Figure 4
Measurements of silver contents in plant tissues and soil matter. (A) Silver accumulation in aboveground parts (shoots) and belowground parts (roots) at the growth stages of S6.0 and S9.0. (B) Silver accumulation in AgNP exposed soil after plants were harvested at S6.0 and S9.0 in terms of μg per g of dry weight of soil sediment with μg of AgNP relative to the fraction of organic and inorganic matter. The presence of AgNPs in control samples might have been due to human errors, i.e., misirrigation of AgNP suspension instead of ddH2O. See the Materials and Methods for the definition of dry weight, organic and inorganic matter. Different letters indicate significantly different soil or tissue concentrations (t-tests, p = 0.05). Abbreviations: dw, dry weight; inorg, inorganic; org, organic; original soil, potting soil from FafardR 4M Mix. Full article ">Figure 5
Inorganic nitrogen nutrients in soil. Inorganic nitrate/nitrite contents of soil were measured after plant tissues were harvested at S6.0 and S9.0. At S6.0, there was no significant difference between control and treated soil. However by S9.0, more nitrate/nitrite remained in the AgNP-treated soil than control soil. Full article ">

0 pages, 1876 KiB

Open AccessArticle

RETRACTED: Potential Impact of Multi-Walled Carbon Nanotubes Exposure to the Seedling Stage of Selected Plant Species

by Parvin Begum, Refi Ikhtiari and Bunshi Fugetsu

Nanomaterials 2014, 4(2), 203-221; https://doi.org/10.3390/nano4020203 - 31 Mar 2014

Cited by 80 | Viewed by 11791 | Retraction

Abstract

Phytotoxicity is a significant consideration in understanding the potential environmental impact of nanoparticles. Abundant experimental data have shown that multi-walled carbon nanotubes (MWNTs) are toxic to plants, but the potential impacts of exposure remain unclear. The objective of the present study was to [...] Read more.

Phytotoxicity is a significant consideration in understanding the potential environmental impact of nanoparticles. Abundant experimental data have shown that multi-walled carbon nanotubes (MWNTs) are toxic to plants, but the potential impacts of exposure remain unclear. The objective of the present study was to evaluate possible phytotoxicity of MWNTs at 0, 20, 200, 1000, and 2000 mg/L with red spinach, lettuce, rice, cucumber, chili, lady’s finger, and soybean, based on root and shoot growth, cell death, and electrolyte leakage at the seedling stage. After 15 days of hydroponic culture, the root and shoot lengths of red spinach, lettuce, and cucumber were significantly reduced following exposure to 1000 mg/L and 2000 mg/L MWNTs. Similar toxic effects occurred regarding cell death and electrolyte leakage. Red spinach and lettuce were most sensitive to MWNTs, followed by rice and cucumber. Very little or no toxic effects were observed for chili, lady’s finger, and soybean. Full article

(This article belongs to the Special Issue Nanotoxicology)

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(a) SEM (Bar: 500 nm); (b) TEM (Bar: 200 nm) micrographs of MWNTs before and after suspended in a modified Hoagland medium; and (c) AFM image of MWNTs before suspended in a modified Hoagland medium, depicts the morphology of MWNTs. Reproduced with permission from reference [<a href="#B17-nanomaterials-04-00203" class="html-bibr">17</a>], Copyright 2012, Elsevier. Full article ">Figure 2
Morphological observations of red spinach, lettuce, rice, and cucumber exposed to MWNTs at 0, 20, 200, 1000, or 2000 mg/L for 15 days. Reproduced with permission from reference [<a href="#B16-nanomaterials-04-00203" class="html-bibr">16</a>], Copyright 2012, Elsevier. Full article ">Figure 3
Growth reduction of red spinach, lettuce, rice, and cucumber after 15 days of exposure to MWNTs. (a,d) Shoot and root weights, respectively, of red spinach, lettuce, and rice. (b,e) Shoot and root weights, respectively, of cucumber. (c,f) Shoot and root lengths, respectively, of red spinach, lettuce, rice, and cucumber. Error bars represent standard deviation of the mean (n = 3). The cucumber data are presented separately because the shoot and root fresh weights were larger than for the other tested plants. Reproduced with permission from reference [<a href="#B16-nanomaterials-04-00203" class="html-bibr">16</a>], Copyright 2012, Elsevier. Full article ">Figure 4
Dose dependency of (a) cell death and (b) membrane integrity caused by 15-day exposure to MWNTs at 0, 20, 200, 1000, or 2000 mg/L in red spinach, lettuce, rice, and cucumber roots. Error bars represent standard deviation of the mean (n = 3). Reproduced with permission from reference [<a href="#B16-nanomaterials-04-00203" class="html-bibr">16</a>], Copyright 2012, Elsevier. Full article ">Figure 5
Detection of ROS in red spinach leaves. 15 day-old fresh leaves treated with or without MWNTs (0 and 1000 mg/L) were used for all measurements. (a,b) Staining using the 3–3'-diaminobenzidine (DAB) (Image obtained with a magnification of 4×). The brown staining indicates the formation of a brown polymerization product when H2O2 reacts with DAB, and viewed with light microscopy. (c,d) Staining using the NBT (Image obtained with a magnification of 4×). The blue staining indicates the formation of a blue formazon product when superoxide reacts with NBT, and viewed with light microscopy. (e,f) Staining with DCFH-DA (Image obtained with a magnification of 4×). The green signal indicates the presence of hydroperoxides inside the cells. Leaves were observed with fluorescence microscopy. Full article ">Figure 6
SEM observation of the red spinach leaf grown in vivo for 15 days in a medium containing Hoagland media only (control) and supplemented with 1000 mg/L MWNTs (treated). Image showing the morphology of control leaf (a,c) epidermis and MWNTs treated leaf (b,d) epidermis showing swelling epidermis. SEM observation of red spinach roots grown in vivo for 15 days in a medium containing Hoagland media only (control, e) and supplemented with 1000 mg L−1 MWNTs (treated, f) showing deformed root cap and elongation zone and deformed epidermis. Bar: a and b, 60 µm; c and d, 15 µm; e, 150 µm; f, 429 µm. Full article ">

552 KiB

Open AccessArticle

Magnetite Nanoparticles Induce Genotoxicity in the Lungs of Mice via Inflammatory Response

by Yukari Totsuka, Kousuke Ishino, Tatsuya Kato, Sumio Goto, Yukie Tada, Dai Nakae, Masatoshi Watanabe and Keiji Wakabayashi

Nanomaterials 2014, 4(1), 175-188; https://doi.org/10.3390/nano4010175 - 18 Mar 2014

Cited by 31 | Viewed by 6934

Abstract

Nanomaterials are useful for their characteristic properties and are commonly used in various fields. Nanosized-magnetite (MGT) is widely utilized in medicinal and industrial fields, whereas their toxicological properties are not well documented. A safety assessment is thus urgently required for MGT, and genotoxicity [...] Read more.

Nanomaterials are useful for their characteristic properties and are commonly used in various fields. Nanosized-magnetite (MGT) is widely utilized in medicinal and industrial fields, whereas their toxicological properties are not well documented. A safety assessment is thus urgently required for MGT, and genotoxicity is one of the most serious concerns. In the present study, we examined genotoxic effects of MGT using mice and revealed that DNA damage analyzed by a comet assay in the lungs of imprinting control region (ICR) mice intratracheally instilled with a single dose of 0.05 or 0.2 mg/animal of MGT was approximately two- to three-fold higher than that of vehicle-control animals. Furthermore, in gpt delta transgenic mice, gpt mutant frequency (MF) in the lungs of the group exposed to four consecutive doses of 0.2 mg MGT was significantly higher than in the control group. Mutation spectrum analysis showed that base substitutions were predominantly induced by MGT, among which G:C to A:T transition and G:C to T:A transversion were the most significant. To clarify the mechanism of mutation caused by MGT, we analyzed the formation of DNA adducts in the lungs of mice exposed to MGT. DNA was extracted from lungs of mice 3, 24, 72 and 168 h after intratracheal instillation of 0.2 mg/body of MGT, and digested enzymatically. 8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and lipid peroxide-related DNA adducts were quantified by stable isotope dilution liquid chromatography-mass spectrometry (LC-MS/MS). Compared with vehicle control, these DNA adduct levels were significantly increased in the MGT-treated mice. In addition to oxidative stress- and inflammation related-DNA adduct formations, inflammatory cell infiltration and focal granulomatous formations were also observed in the lungs of MGT-treated mice. Based on these findings, it is suggested that inflammatory responses are probably involved in the genotoxicity induced by MGT in the lungs of mice. Full article

(This article belongs to the Special Issue Nanotoxicology)

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Figure 1
Crystal appearance and zeta potential of magnetite nanoparticles (MGT): (a) Scanning electron microscopy (SEM) micrographs of MGT obtained at E=20 kV,×300,000;and (b) Size distribution of MGT measured in water, 0.2 μg/mL. Full article ">Figure 2
DNA damage in the lungs of imprinting control region (ICR) mice intratracheally instilled with MGT. DNA damage was measured by comet assay. Male micewere treated at a dose of 0.05 mg or 0.2 mg of particles per animal, and sacrificed 3 h after particle administration. The values represent the means of data for five animals ± SE. ** P < 0.01, by the Dunnett’s test after one-way analysis of variance vs. the corresponding vehicle control mice. Full article ">Figure 3
The gpt mutation frequencies in the lungs of mice after multiple intratracheal instillations of MGT. Male mice were treated with multiple (0.05 or 0.2 mg/mouse × 4 times) doses of MGT, and mice were sacrificed eight weeks after MGT administration. The data represent the mean ± SD; * P < 0.05 by the Student’s t-test vs. the corresponding vehicle control mice. Full article ">Figure 4
Microscopic findings in the lungs of gpt delta mice intratracheally instilled with MGT.Representative histopathology of the lungs of: (a) a control mouse given vehicle (once a week for 4 weeks; killed at 22 weeks of age); and (b,c) a mouse given multiple doses of 0.2 mg MGT (killed at 22 weeks of age). The brown-colored material is MGT. Full article ">Figure 5
Oxidative and lipid peroxide-related DNA adduct formation induced by MGT exposure in the lungs of ICR mice. DNA was extracted from the lungs 3, 24, 72 and 168 h after intratracheal instillation of 0.2 mg of MGT, and was digested enzymatically. Control samples were obtained from the lungs of mice given the vehicle for the same durations of MGT exposure. 8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and two types of Hε-adduct were quantified by stable isotope dilution liquid chromatography-mass spectrometry (LC-MS/MS). Asterisks (* and **) indicate a significant difference (P < 0.05 and P < 0.01) from vehicle control (treatment with 0.05% (v/v) Tween-80) at the same point in the Student’s t-test. Full article ">

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Open AccessReview

Autophagy as a Possible Underlying Mechanism of Nanomaterial Toxicity

by Vanessa Cohignac, Marion Julie Landry, Jorge Boczkowski and Sophie Lanone

Nanomaterials 2014, 4(3), 548-582; https://doi.org/10.3390/nano4030548 - 8 Jul 2014

Cited by 53 | Viewed by 12893

Abstract

The rapid development of nanotechnologies is raising safety concerns because of the potential effects of engineered nanomaterials on human health, particularly at the respiratory level. Since the last decades, many in vivo studies have been interested in the pulmonary effects of different classes [...] Read more.

The rapid development of nanotechnologies is raising safety concerns because of the potential effects of engineered nanomaterials on human health, particularly at the respiratory level. Since the last decades, many in vivo studies have been interested in the pulmonary effects of different classes of nanomaterials. It has been shown that some of them can induce toxic effects, essentially depending on their physico-chemical characteristics, but other studies did not identify such effects. Inflammation and oxidative stress are currently the two main mechanisms described to explain the observed toxicity. However, the exact underlying mechanism(s) still remain(s) unknown and autophagy could represent an interesting candidate. Autophagy is a physiological process in which cytoplasmic components are digested via a lysosomal pathway. It has been shown that autophagy is involved in the pathogenesis and the progression of human diseases, and is able to modulate the oxidative stress and pro-inflammatory responses. A growing amount of literature suggests that a link between nanomaterial toxicity and autophagy impairment could exist. In this review, we will first summarize what is known about the respiratory effects of nanomaterials and we will then discuss the possible involvement of autophagy in this toxicity. This review should help understand why autophagy impairment could be taken as a promising candidate to fully understand nanomaterials toxicity. Full article

(This article belongs to the Special Issue Nanotoxicology)

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206 KiB

Open AccessReview

Carbon Nanotubes and Chronic Granulomatous Disease

by Barbara P. Barna, Marc A. Judson and Mary Jane Thomassen

Nanomaterials 2014, 4(2), 508-521; https://doi.org/10.3390/nano4020508 - 23 Jun 2014

Cited by 18 | Viewed by 5758

Abstract

Use of nanomaterials in manufactured consumer products is a rapidly expanding industry and potential toxicities are just beginning to be explored. Combustion-generated multiwall carbon nanotubes (MWCNT) or nanoparticles are ubiquitous in non-manufacturing environments and detectable in vapors from diesel fuel, methane, propane, and [...] Read more.

Use of nanomaterials in manufactured consumer products is a rapidly expanding industry and potential toxicities are just beginning to be explored. Combustion-generated multiwall carbon nanotubes (MWCNT) or nanoparticles are ubiquitous in non-manufacturing environments and detectable in vapors from diesel fuel, methane, propane, and natural gas. In experimental animal models, carbon nanotubes have been shown to induce granulomas or other inflammatory changes. Evidence suggesting potential involvement of carbon nanomaterials in human granulomatous disease, has been gathered from analyses of dusts generated in the World Trade Center disaster combined with epidemiological data showing a subsequent increase in granulomatous disease of first responders. In this review we will discuss evidence for similarities in the pathophysiology of carbon nanotube-induced pulmonary disease in experimental animals with that of the human granulomatous disease, sarcoidosis. Full article

(This article belongs to the Special Issue Nanotoxicology)

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Mechanisms Underlying Cytotoxicity Induced by Engineered Nanomaterials: A Review of In Vitro Studies

by Daniele R. Nogueira, Montserrat Mitjans, Clarice M.B. Rolim and M. Pilar Vinardell

Nanomaterials 2014, 4(2), 454-484; https://doi.org/10.3390/nano4020454 - 12 Jun 2014

Cited by 45 | Viewed by 9304

Abstract

Engineered nanomaterials are emerging functional materials with technologically interesting properties and a wide range of promising applications, such as drug delivery devices, medical imaging and diagnostics, and various other industrial products. However, concerns have been expressed about the risks of such materials and [...] Read more.

Engineered nanomaterials are emerging functional materials with technologically interesting properties and a wide range of promising applications, such as drug delivery devices, medical imaging and diagnostics, and various other industrial products. However, concerns have been expressed about the risks of such materials and whether they can cause adverse effects. Studies of the potential hazards of nanomaterials have been widely performed using cell models and a range of in vitro approaches. In the present review, we provide a comprehensive and critical literature overview on current in vitro toxicity test methods that have been applied to determine the mechanisms underlying the cytotoxic effects induced by the nanostructures. The small size, surface charge, hydrophobicity and high adsorption capacity of nanomaterial allow for specific interactions within cell membrane and subcellular organelles, which in turn could lead to cytotoxicity through a range of different mechanisms. Finally, aggregating the given information on the relationships of nanomaterial cytotoxic responses with an understanding of its structure and physicochemical properties may promote the design of biologically safe nanostructures. Full article

(This article belongs to the Special Issue Nanotoxicology)

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Full article ">Figure 1
Light microscopic morphology and kinetics of macrophage aggregation in 2D and 3D cultures. BMDM were exposed to 0.5 μg/mL (0.38 μg/cm2) of particulates. Formation of stable cellular aggregates was evaluated at 3 and 14 days post-exposure. Macrophages were stained with May-Grünwald-Giemsa. Reprinted from [<a href="#B65-nanomaterials-04-00454" class="html-bibr">65</a>]. Open Access article, under the terms of Creative Commons Attribution License. Copyright 2011, Licensee Biomed Central Ltd. Full article ">Figure 2
(A) Morphological changes of nano-chelidonines (NCs) (10 and 20 µg/mL)-treated HepG2 cells observed by phase contrast microscope; (B) nuclear condensation assessment of control and treated cells by DAPI staining were analyzed through fluorescence microscopy; (C) the increased apoptotic cells were determined by AO/EB staining through fluorescence microscopy. The nuclear condensation and transformation of color green to reddish orange with fragmented nuclear membrane represents the induction of apoptosis in the treated cells with respect to control ones; (D) assessment of cellular apoptosis by externalizing phosphatidyl serine through Annexin V/PI assay by flow-cytometric analysis. Reprinted with permission from [<a href="#B34-nanomaterials-04-00454" class="html-bibr">34</a>]. Copyright 2013, Elsevier. Full article ">Figure 3
Measurement of ROS production in A549 cells after 24 h NP exposure. The DCF fluorescence of treated cells was normalized to that of untreated controls and reported as mean ± SD. Reprinted with permission from [<a href="#B45-nanomaterials-04-00454" class="html-bibr">45</a>]. Copyright 2013, Elsevier. Full article ">Figure 4
Assessment of the effects of chitosan NPs encapsulating MTX (MTX-CS-NPs) on lysosomal membrane permeabilization in HeLa cells as visualized via AO staining. In untreated control cells, lysosomes can be seen as red–orange granules and cytoplasm has a diffuse green fluorescence. In cells with lysosomal membrane damage (HeLa cells treated with 50 mg/mL MTX-CS-NPs), lysosomes exhibit a shift from red–orange to a yellow–green fluorescent color. Reprinted with permission from [<a href="#B7-nanomaterials-04-00454" class="html-bibr">7</a>]. Copyright 2013, Elsevier. Full article ">Figure 5
Comet data (% tail DNA) of human lymphocytes treated with different concentrations of titanium dioxide (TiO2) nanoparticle; * P < 0.05. Reprinted with permission from [<a href="#B37-nanomaterials-04-00454" class="html-bibr">37</a>]. Copyright 2013, John Wiley and Sons. Full article ">

1033 KiB

Open AccessReview

Emergent Properties and Toxicological Considerations for Nanohybrid Materials in Aquatic Systems

by Navid B. Saleh, A. R. M. Nabiul Afrooz, Joseph H. Bisesi,, Jr., Nirupam Aich, Jaime Plazas-Tuttle and Tara Sabo-Attwood

Nanomaterials 2014, 4(2), 372-407; https://doi.org/10.3390/nano4020372 - 3 Jun 2014

Cited by 41 | Viewed by 12682

Abstract

Conjugation of multiple nanomaterials has become the focus of recent materials development. This new material class is commonly known as nanohybrids or “horizon nanomaterials”. Conjugation of metal/metal oxides with carbonaceous nanomaterials and overcoating or doping of one metal with another have been pursued [...] Read more.

Conjugation of multiple nanomaterials has become the focus of recent materials development. This new material class is commonly known as nanohybrids or “horizon nanomaterials”. Conjugation of metal/metal oxides with carbonaceous nanomaterials and overcoating or doping of one metal with another have been pursued to enhance material performance and/or incorporate multifunctionality into nano-enabled devices and processes. Nanohybrids are already at use in commercialized energy, electronics and medical products, which warrant immediate attention for their safety evaluation. These conjugated ensembles likely present a new set of physicochemical properties that are unique to their individual component attributes, hence increasing uncertainty in their risk evaluation. Established toxicological testing strategies and enumerated underlying mechanisms will thus need to be re-evaluated for the assessment of these horizon materials. This review will present a critical discussion on the altered physicochemical properties of nanohybrids and analyze the validity of existing nanotoxicology data against these unique properties. The article will also propose strategies to evaluate the conjugate materials’ safety to help undertake future toxicological research on the nanohybrid material class. Full article

(This article belongs to the Special Issue Nanotoxicology)

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