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Philip Demokritou - One of the best experts on this subject based on the ideXlab platform.

  • in vivo epigenetic effects induced by Engineered nanomaterials a case study of copper oxide and laser printer emitted Engineered Nanoparticles
    Nanotoxicology, 2016
    Co-Authors: Xiaoyan Lu, Isabelle R Miousse, Sandra V Pirela, Jodene K Moore, Stepan Melnyk, Igor Koturbash, Philip Demokritou
    Abstract:

    AbstractEvidence continues to grow on potential environmental health hazards associated with Engineered nanomaterials (ENMs). While the geno- and cytotoxic effects of ENMs have been investigated, their potential to target the epigenome remains largely unknown. The aim of this study is two-fold: 1) determining whether or not industry relevant ENMs can affect the epigenome in vivo and 2) validating a recently developed in vitro epigenetic screening platform for inhaled ENMs. Laser printer-emitted Engineered Nanoparticles (PEPs) released from nano-enabled toners during consumer use and copper oxide (CuO) were chosen since these particles induced significant epigenetic changes in a recent in vitro companion study. In this study, the epigenetic alterations in lung tissue, alveolar macrophages and peripheral blood from intratracheally instilled mice were evaluated. The methylation of global DNA and transposable elements (TEs), the expression of the DNA methylation machinery and TEs, in addition to general toxic...

  • in vivo epigenetic effects induced by Engineered nanomaterials a case study of copper oxide and laser printer emitted Engineered Nanoparticles
    Nanotoxicology, 2016
    Co-Authors: Isabelle R Miousse, Sandra V Pirela, Jodene K Moore, Stepan Melnyk, Igor Koturbash, Philip Demokritou
    Abstract:

    Evidence continues to grow on potential environmental health hazards associated with Engineered nanomaterials (ENMs). While the geno- and cytotoxic effects of ENMs have been investigated, their potential to target the epigenome remains largely unknown. The aim of this study is two-fold: 1) determining whether or not industry relevant ENMs can affect the epigenome in vivo and 2) validating a recently developed in vitro epigenetic screening platform for inhaled ENMs. Laser printer-emitted Engineered Nanoparticles (PEPs) released from nano-enabled toners during consumer use and copper oxide (CuO) were chosen since these particles induced significant epigenetic changes in a recent in vitro companion study. In this study, the epigenetic alterations in lung tissue, alveolar macrophages and peripheral blood from intratracheally instilled mice were evaluated. The methylation of global DNA and transposable elements (TEs), the expression of the DNA methylation machinery and TEs, in addition to general toxicological effects in the lung were assessed. CuO exhibited higher cell-damaging potential to the lung, while PEPs showed a greater ability to target the epigenome. Alterations in the methylation status of global DNA and TEs, and expression of TEs and DNA machinery in mouse lung were observed after exposure to CuO and PEPs. Additionally, epigenetic changes were detected in the peripheral blood after PEPs exposure. Altogether, CuO and PEPs can induce epigenetic alterations in a mouse experimental model, which in turn confirms that the recently developed in vitro epigenetic platform using macrophage and epithelial cell lines can be successfully utilized in the epigenetic screening of ENMs.

  • Evaluation of environmental filtration control of Engineered Nanoparticles using the Harvard Versatile Engineered Nanomaterial Generation System (VENGES)
    Journal of Nanoparticle Research, 2012
    Co-Authors: Candace S.-j. Tsai, Philip Demokritou, Manuel E. Echevarría-vega, Georgios A. Sotiriou, Christopher Santeufemio, Daniel Schmidt, Michael Ellenbecker
    Abstract:

    Applying engineering controls to airborne Engineered Nanoparticles (ENPs) is critical to prevent environmental releases and worker exposure. This study evaluated the effectiveness of two air sampling and six air cleaning fabric filters at collecting ENPs using industrially relevant flame-made Engineered Nanoparticles generated using a versatile Engineered nanomaterial generation system (VENGES), recently designed and constructed at Harvard University. VENGES has the ability to generate metal and metal oxide exposure atmospheres while controlling important particle properties such as primary particle size, aerosol size distribution, and agglomeration state. For this study, amorphous SiO_2 ENPs with a 15.4 nm primary particle size were generated and diluted with HEPA-filtered air. The aerosol was passed through the filter samples at two different filtration face velocities (2.3 and 3.5 m/min). Particle concentrations as a function of particle size were measured upstream and downstream of the filters using a specially designed filter test system to evaluate filtration efficiency. Real time instruments (FMPS and APS) were used to measure particle concentration for diameters from 5 to 20,000 nm. Membrane-coated fabric filters were found to have enhanced nanoparticle collection efficiency by 20–46 % points compared to non-coated fabric and could provide collection efficiency above 95 %.

Peter H. Santschi - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Engineered Nanoparticles on Exopolymeric Substances Release from Marine Phytoplankton
    SpringerOpen, 2017
    Co-Authors: Meng-hsuen Chiu, Peter H. Santschi, Zafir A. Khan, Santiago G. Garcia, Agnes Kagiri, Javier Ramos, Shih-ming Tsai, Hunter W. Drobenaire, Antonietta Quigg
    Abstract:

    Abstract Engineered Nanoparticles (ENPs), products from modern nanotechnologies, can potentially impact the marine environment to pose serious threats to marine ecosystems. However, the cellular responses of marine phytoplankton to ENPs are still not well established. Here, we investigate four different diatom species (Odontella mobiliensis, Skeletonema grethae, Phaeodactylum tricornutum, Thalassiosira pseudonana) and one green algae (Dunaliella tertiolecta) for their extracellular polymeric substances (EPS) release under model ENP treatments: 25 nm titanium dioxide (TiO2), 10–20 nm silicon dioxide (SiO2), and 15–30 nm cerium dioxide (CeO2). We found SiO2 ENPs can significantly stimulate EPS release from these algae (200–800%), while TiO2 ENP exposure induced the lowest release. Furthermore, the increase of intracellular Ca2+ concentration can be triggered by ENPs, suggesting that the EPS release process is mediated through Ca2+ signal pathways. With better understanding of the cellular mechanism mediated ENP-induced EPS release, potential preventative and safety measures can be developed to mitigate negative impact on the marine ecosystem

  • direct and indirect toxic effects of Engineered Nanoparticles on algae role of natural organic matter
    ACS Sustainable Chemistry & Engineering, 2013
    Co-Authors: Antonietta Quigg, Ai-jun Miao, Saijin Zhang, Weichun Chin, Chishuo Chen, Yuelu Jiang, Kathleen A Schwehr, Chen Xu, Peter H. Santschi
    Abstract:

    In order to assess the overall risk posed by Engineered Nanoparticles (ENPs), the biological effects of this emergent pollutant to aquatic ecosystems must be evaluated. We present findings from studies conducted with a diversity of ENPs (metallic, quantum dots) on a variety of freshwater and marine algae (phytoplankton) illustrating both their direct and indirect effects. We show that in general, while the surface properties of ENPs govern their aggregation behavior and ionic strength controls their dissolution, exopolymeric substances (EPS) produced by algae determine their potential to be toxic and thereby movement through the water column and food web. The production of EPS reduces the impact of ENPs (bioavailability and toxicity) and/or their ions on cellular activities of algae. It does not however directly reduce the aggregation and/or solubility of ENPs but rather affects their stability. Complicating understanding of these interactions is the great assortment of surface coatings for ENPs. This per...

  • the algal toxicity of silver Engineered Nanoparticles and detoxification by exopolymeric substances
    Environmental Pollution, 2009
    Co-Authors: Ai-jun Miao, Antonietta Quigg, Peter H. Santschi, K A Schwehr, Saijin Zhang, Zhiping Luo
    Abstract:

    Abstract In this study, we report that silver ions (Ag + ) from the oxidative dissolution of silver Engineered Nanoparticles (Ag-ENs) determined the EN toxicity to the marine diatom Thalassiosira weissflogii . Most of the Ag-ENs formed non-toxic aggregates (>0.22 μm) in seawater. When the free Ag + concentration ([Ag + ] F ) was greatly reduced by diafiltration or thiol complexation, no toxicity was observed, even though the Ag-ENs were better dispersed in the presence of thiols with up to 1.08 × 10 −5  M Ag-ENs found in the + ] F . Both dissolved and particulate polysaccharide concentrations were higher for nutrient-limited cells, coinciding with their higher Ag + tolerance, suggesting that EPS may be involved in Ag + detoxification.

  • the algal toxicity of silver Engineered Nanoparticles and detoxification by exopolymeric substances
    Environmental Pollution, 2009
    Co-Authors: Ai-jun Miao, Antonietta Quigg, Peter H. Santschi, K A Schwehr, Saijin Zhang, Zhiping Luo
    Abstract:

    In this study, we report that silver ions (Ag(+)) from the oxidative dissolution of silver Engineered Nanoparticles (Ag-ENs) determined the EN toxicity to the marine diatom Thalassiosira weissflogii. Most of the Ag-ENs formed non-toxic aggregates (>0.22 microm) in seawater. When the free Ag(+) concentration ([Ag(+)](F)) was greatly reduced by diafiltration or thiol complexation, no toxicity was observed, even though the Ag-ENs were better dispersed in the presence of thiols with up to 1.08 x 10(-5) M Ag-ENs found in the <0.22 microm fraction, which are orders of magnitude higher than predicted for the natural aquatic environment. The secretion of polysaccharide-rich algal exopolymeric substances (EPS) significantly increased at increasing [Ag(+)](F). Both dissolved and particulate polysaccharide concentrations were higher for nutrient-limited cells, coinciding with their higher Ag(+) tolerance, suggesting that EPS may be involved in Ag(+) detoxification.

  • Environmental behavior and ecotoxicity of Engineered Nanoparticles to algae, plants, and fungi
    Ecotoxicology, 2008
    Co-Authors: Enrique Navarro, Ai-jun Miao, Antonietta Quigg, Peter H. Santschi, Nanna B Hartmann, Anders Baun, Renata Behra, Juliane Filser, Laura Sigg
    Abstract:

    Developments in nanotechnology are leading to a rapid proliferation of new materials that are likely to become a source of Engineered Nanoparticles (ENPs) to the environment, where their possible ecotoxicological impacts remain unknown. The surface properties of ENPs are of essential importance for their aggregation behavior, and thus for their mobility in aquatic and terrestrial systems and for their interactions with algae, plants and, fungi. Interactions of ENPs with natural organic matter have to be considered as well, as those will alter the ENPs aggregation behavior in surface waters or in soils. Cells of plants, algae, and fungi possess cell walls that constitute a primary site for interaction and a barrier for the entrance of ENPs. Mechanisms allowing ENPs to pass through cell walls and membranes are as yet poorly understood. Inside cells, ENPs might directly provoke alterations of membranes and other cell structures and molecules, as well as protective mechanisms. Indirect effects of ENPs depend on their chemical and physical properties and may include physical restraints (clogging effects), solubilization of toxic ENP compounds, or production of reactive oxygen species. Many questions regarding the bioavailability of ENPs, their uptake by algae, plants, and fungi and the toxicity mechanisms remain to be elucidated.

Alistair B A Boxall - One of the best experts on this subject based on the ideXlab platform.

  • regulatory ecotoxicity testing of Engineered Nanoparticles are the results relevant to the natural environment
    Nanotoxicology, 2014
    Co-Authors: Sujung Park, Jonathan G C Veinot, J W Woodhall, Malcolm S Cresser, Alistair B A Boxall
    Abstract:

    Engineered Nanoparticles (ENPs) will be released to the environment during use or following the disposal of ENPcontaining products and concerns have been raised over the risks of ENPs to the environment. Many studies have explored the toxicity of ENPs to aquatic organisms but these studies have usually been performed with little understanding of the ENPs’ behaviour in the test media and the relationship between behaviour in the media to behaviour in natural waters. This study evaluated and compared the aggregation behaviour of four model gold nanoparticle (NP) types (coated with neutral, negative, positive and amphoteric cappings) in standard ecotoxicity test media and natural waters. The effects of humic acid (HA) and test organisms on aggregation were also investigated. In standard media, positive and neutral NPs were stable, whereas amphoteric and negative NPs generally showed substantial aggregation. In natural waters, amphoteric NPs were generally found to be stable, neutral and positive NPs showed substantial aggregation while negative NPs were stable in some waters and unstable in others. HA addition stabilised the amphoteric NPs, destabilised the positive NPs and had no effect on stability of negative NPs. The presence of invertebrates generally lowered the degree of particle aggregation while macrophytes had no effect. Given the dramatically different behaviours of ENPs in various standard media and natural waters, current regulatory testing may either under- or overestimate the toxicity of nanomaterials to aquatic organisms. Therefore, there is a pressing need to employ ecotoxicity media which better represent the behaviour of ENPs in natural system.

  • considerations for environmental fate and ecotoxicity testing to support environmental risk assessments for Engineered Nanoparticles
    Journal of Chromatography A, 2009
    Co-Authors: Karen Tiede, Martin Hassellov, Alistair B A Boxall, Eike Breitbarth, Qasim Chaudhry
    Abstract:

    There is an increasing concern over the safety of Engineered Nanoparticles (ENPs) to humans and the environment and it is likely that the environmental risks of these particles will have to be tested under regulatory schemes such as REACH. Due to their unique properties and the fact that their detection and characterisation in complex matrices is challenging, existing analytical methods and test approaches for assessing environmental risk may not be appropriate for ENPs. In this article we discuss the challenges associated with the testing of ENPs to generate data on persistence, mobility, bioavailability and ecotoxicity in the environment. It is essential that careful consideration is given to the selection of the test material, the test system (including test vessels and study media) and the test exposure conditions. During a study it is critical that not only the concentration of the ENP is determined but also its characteristics (e.g. size, shape, degree of aggregation and dissolution). A range of analytical techniques is available including microscopy-based approaches (e.g transmission and scanning electron microscopy), dynamic light scattering, and size separation approaches (e.g. field flow fractionation and hydrodynamic chromatography) coupled to detection methods such as inductively coupled plasma MS. All of these have their disadvantages: some are unable to distinguish between ENPs and natural interferences; some techniques require sample preparation approaches that can introduce artefacts; and others are complex and time-consuming. A combination of techniques is therefore needed. Our knowledge in this area is still limited, and co-ordinated research is required to gain a better understanding of the factors and processes affecting ENP fate and effects in the environment as well as to develop more usable, robust and sensitive methods for characterisation and detection of ENPs in environmental systems.

  • detection and characterization of Engineered Nanoparticles in food and the environment
    Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2008
    Co-Authors: Karen Tiede, Alistair B A Boxall, S P Tear, John Lewis, Helen David, Martin Hassellov
    Abstract:

    Nanotechnology is developing rapidly and, in the future, it is expected that increasingly more products will contain some sort of nanomaterial. However, to date, little is known about the occurrence, fate and toxicity of Nanoparticles. The limitations in our knowledge are partly due to the lack of methodology for the detection and characterisation of Engineered Nanoparticles in complex matrices, i.e. water, soil or food. This review provides an overview of the characteristics of Nanoparticles that could affect their behaviour and toxicity, as well as techniques available for their determination. Important properties include size, shape, surface properties, aggregation state, solubility, structure and chemical composition. Methods have been developed for natural or Engineered nanomaterials in simple matrices, which could be optimized to provide the necessary information, including microscopy, chromatography, spectroscopy, centrifugation, as well as filtration and related techniques. A combination of these is often required. A number of challenges will arise when analysing environmental and food materials, including extraction challenges, the presence of analytical artifacts caused by sample preparation, problems of distinction between natural and Engineered Nanoparticles and lack of reference materials. Future work should focus on addressing these challenges.

Karen Tiede - One of the best experts on this subject based on the ideXlab platform.

  • considerations for environmental fate and ecotoxicity testing to support environmental risk assessments for Engineered Nanoparticles
    Journal of Chromatography A, 2009
    Co-Authors: Karen Tiede, Martin Hassellov, Alistair B A Boxall, Eike Breitbarth, Qasim Chaudhry
    Abstract:

    There is an increasing concern over the safety of Engineered Nanoparticles (ENPs) to humans and the environment and it is likely that the environmental risks of these particles will have to be tested under regulatory schemes such as REACH. Due to their unique properties and the fact that their detection and characterisation in complex matrices is challenging, existing analytical methods and test approaches for assessing environmental risk may not be appropriate for ENPs. In this article we discuss the challenges associated with the testing of ENPs to generate data on persistence, mobility, bioavailability and ecotoxicity in the environment. It is essential that careful consideration is given to the selection of the test material, the test system (including test vessels and study media) and the test exposure conditions. During a study it is critical that not only the concentration of the ENP is determined but also its characteristics (e.g. size, shape, degree of aggregation and dissolution). A range of analytical techniques is available including microscopy-based approaches (e.g transmission and scanning electron microscopy), dynamic light scattering, and size separation approaches (e.g. field flow fractionation and hydrodynamic chromatography) coupled to detection methods such as inductively coupled plasma MS. All of these have their disadvantages: some are unable to distinguish between ENPs and natural interferences; some techniques require sample preparation approaches that can introduce artefacts; and others are complex and time-consuming. A combination of techniques is therefore needed. Our knowledge in this area is still limited, and co-ordinated research is required to gain a better understanding of the factors and processes affecting ENP fate and effects in the environment as well as to develop more usable, robust and sensitive methods for characterisation and detection of ENPs in environmental systems.

  • detection and characterization of Engineered Nanoparticles in food and the environment
    Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2008
    Co-Authors: Karen Tiede, Alistair B A Boxall, S P Tear, John Lewis, Helen David, Martin Hassellov
    Abstract:

    Nanotechnology is developing rapidly and, in the future, it is expected that increasingly more products will contain some sort of nanomaterial. However, to date, little is known about the occurrence, fate and toxicity of Nanoparticles. The limitations in our knowledge are partly due to the lack of methodology for the detection and characterisation of Engineered Nanoparticles in complex matrices, i.e. water, soil or food. This review provides an overview of the characteristics of Nanoparticles that could affect their behaviour and toxicity, as well as techniques available for their determination. Important properties include size, shape, surface properties, aggregation state, solubility, structure and chemical composition. Methods have been developed for natural or Engineered nanomaterials in simple matrices, which could be optimized to provide the necessary information, including microscopy, chromatography, spectroscopy, centrifugation, as well as filtration and related techniques. A combination of these is often required. A number of challenges will arise when analysing environmental and food materials, including extraction challenges, the presence of analytical artifacts caused by sample preparation, problems of distinction between natural and Engineered Nanoparticles and lack of reference materials. Future work should focus on addressing these challenges.

  • nanoparticle analysis and characterization methodologies in environmental risk assessment of Engineered Nanoparticles
    Ecotoxicology, 2008
    Co-Authors: Martin Hassellov, J W Readman, James F Ranville, Karen Tiede
    Abstract:

    Environmental risk assessments of Engineered Nanoparticles require thorough characterization of Nanoparticles and their aggregates. Furthermore, quantitative analytical methods are required to determine environmental concentrations and enable both effect and exposure assessments. Many methods still need optimization and development, especially for new types of Nanoparticles in water, but extensive experience can be gained from the fields of environmental chemistry of natural nanomaterials and from fundamental colloid chemistry. This review briefly describes most methods that are being exploited in nanoecotoxicology for analysis and characterization of nanomaterials. Methodological aspects are discussed in relation to the fields of nanometrology, particle size analysis and analytical chemistry. Differences in both the type of size measures (length, radius, aspect ratio, etc.), and the type of average or distributions afforded by the specific measures are compared. The strengths of single particle methods, such as electron microscopy and atomic force microscopy, with respect to imaging, shape determinations and application to particle process studies are discussed, together with their limitations in terms of counting statistics and sample preparation. Methods based on the measurement of particle populations are discussed in terms of their quantitative analyses, but the necessity of knowing their limitations in size range and concentration range is also considered. The advantage of combining complementary methods is highlighted.

Diana Boraschi - One of the best experts on this subject based on the ideXlab platform.

  • induction of innate immune memory by Engineered Nanoparticles in monocytes macrophages from hypothesis to reality
    Frontiers in Immunology, 2020
    Co-Authors: Paola Italiani, Giacomo Della Camera, Diana Boraschi
    Abstract:

    The capacity of Engineered Nanoparticles to activate cells of the innate immune system, in particular monocytes and macrophages, is considered at the basis of their toxic/inflammatory effects. It is, however, evident that even Nanoparticles that do not directly induce inflammatory activation, and are therefore considered as safe, can nevertheless induce epigenetic modifications and affect metabolic pathways in monocytes and macrophages. Since epigenetic and metabolic changes are the main mechanisms of innate memory, we had previously proposed that Nanoparticles can induce/modulate innate memory, that is, have the ability of shaping the secondary response to inflammatory challenges. In light of new data, it is now possible to support the original hypothesis and show that different types of Nanoparticles can both directly induce innate memory, priming macrophages for a more potent response to subsequent stimuli, and modulate bacteria-induced memory by attenuating the priming-induced enhancement. This evidence raises two important issues. First, in addition to overt toxic/inflammatory effects, we should consider evaluating the capacity to induce innate memory and the related epigenetic and metabolic changes in the immunosafety assessment of nanomaterials, since modulation of innate memory may be at the basis of long-term unwanted immunological effects. The other important consideration is that this capacity of nanomaterials could open a new avenue in immunomodulation and the possibility of using Engineered nanomaterials for improving immune responses to vaccines and resistance to infections, and modulate anomalous immune/inflammatory reactions in chronic inflammatory diseases, autoimmunity, and a range of other immune-related pathologies.

  • induction of innate immune memory by Engineered Nanoparticles a hypothesis that may become true
    Frontiers in Immunology, 2017
    Co-Authors: Paola Italiani, Diana Boraschi
    Abstract:

    Innate immune memory is the capacity of cells of the innate immune system, such as monocytes and macrophages, to react differently to an inflammatory or infectious challenge if previously exposed to the same or to another agent. Innate immune memory is a protective mechanism, based on epigenetic reprogramming, that ensures effective protection while limiting side effects of tissue damage, by controlling innate/inflammatory responses to repeated stimulations. Engineered Nanoparticles are novel challenges for our innate immune system, and their ability to induce inflammatory activation, thereby posing health risks, is currently being investigated with controversial results. Besides their putative direct inflammation-inducing effects, we hypothesize that Engineered Nanoparticles may induce innate memory based on their capacity to induce epigenetic modulation of gene expression. Preliminary results using non-toxic non-inflammatory gold Nanoparticles show that in fact Nanoparticles can induce memory by modulating in either positive or negative fashion the inflammatory activation of human monocytes to a subsequent bacterial challenge. The possibility of shaping innate/inflammatory reactivity with Nanoparticles could open the way to future novel approaches of preventive and therapeutic immunomodulation.