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Ahmad, Abo Markeb Ahmad Mohamed. "Environmental applications of engineered nanomaterials: synthesis and characterization." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/454768.
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Aquesta tesi es basa en el desenvolupament (síntesi) de diferents nanomaterials per a la seva aplicació com a materials adsorbents per a l'eliminació de contaminants en aigua (anions inorgànics, metalls pesats i pesticides) i per l'adsorció de gas metà. El desenvolupament dels diferents materials s'ha basat en una extensa recerca bibliogràfica de l'estat de l'art dels materials utilitzats actualment per a aquesta aplicació, i s'ha tractat de millorar l'eficiència del procés mitjançant l'ús de nanomaterials. Amb aquest objectiu s’han sintetitzat materials magnètics per diferents mètodes. En alguns casos, aquests han estat funcionalitzats amb grups orgànics per adaptar i/o millorar la seva funció d'adsorció o estabilitzar-los en suports (polímers, zeolites, esponges, etc.) per millorar la seva aplicació a una escala real en un futur. A més, es va desenvolupar un nou mètode per a la formació de nanopartícules core-shell amb un nucli de magnetita. Tots els nanomaterials sintetitzats s'han caracteritzat en profunditat, utilitzant les tècniques més avançades per a la caracterització dels nanomaterials. Tècniques com ara la microscòpia electrònica, difracció de raigs X, entre d'altres, permeten conèixer les característiques i propietats dels materials (mida, dispersió, estructura cristal·lina, etc.) i per tant concloure la seva contribució a l'eficàcia de cada un dels materials adsorbents.
Pel que fa als contaminants en aigua, el treball se centra en el fluorur, el fosfat, el nitrat, els metalls cadmi i níquel i pesticides, destacant l'obtenció de resultats excepcionals per a les nanopartícules de Ce-Ti@Fe3O4.
En el cas de tractament de gas, per una banda s'ha desenvolupat un nou nanomaterial basat en nanopartícules magnètiques estabilitzades en esponges de poliuretà que ha presentat resultats interessants per a l'adsorció de metà. A més, s'ha col·laborat amb la Institut Català de Nanotecnologia per a l'aplicabilitat dels Metal Organic Frameworks en l'oxidació de CO.
Una altra aplicació que s'ha donat a les nanopartícules magnètiques ha estat la seva utilització en la separació de algues procedents de processos de tractament d’aigües, per tal de substituir el procés actual de decantació.
Amb tot això, la tesi ofereix una gamma de nanomaterials per a diferents usos en enginyeria ambiental, amb la possibilitat d'investigar i desenvolupar en la seva aplicabilitat a gran escala. Amb aquesta finalitat, es proporcionen diferents solucions per a la millora del medi ambient.<br>This thesis is based on the development (synthesis) of different nanomaterials for their application as adsorbent materials for the removal of pollutants from water (inorganic anions, heavy metals and pesticides) and for the adsorption of methane gas. The development of the different materials has been based on an extensive bibliographical search of the state of the art of the materials currently used for this application, and it has been tried to improve the efficiency of the process by using nanomaterials. Thus, magnetic (magnetite) nanoparticles are synthesized by different methods. These are functionalized with organic groups to adapt and/or improve their adsorption function or stabilize in supports (polymers, zeolites, sponges, etc.) to improve their application on a real scale. In addition, a new method for the formation of core-shell nanoparticles with a magnetite core is developed. All the synthesized nanomaterials have been characterized in depth, using the most advanced techniques for the characterization of nanomaterials. Techniques such as electron microscopy, X-ray diffraction, among others, allow to know the characteristics and properties of the materials (size, dispersion, crystallinity, structure, etc.) and thus conclude their contribution to the efficiency of their application with adsorbent material.
As for the contaminants in water, the work focuses on fluoride, phosphates, nitrates, cadmium, nickel and pesticides, obtaining outstanding results for the nanoparticles of Ce-Ti @Fe3O4.
In the case of gas treatment, on the one hand has developed a new nanomaterial based on magnetic nanoparticles stabilized in polyurethane sponges which present interesting results for the adsorption of methane and great applicability on a real scale. In addition, we have collaborated with the Institut Català de Nanotecnologia for the applicability of Metal Organic Frameworks in the oxidation of CO.
Another application that has been given to magnetic nanoparticles has been its use to separate algae from wastewater treatment processes, in order to substitute the current sedimentation processes.
With all this, the thesis offers a range of nanomaterials for different uses in environmental engineering, with the possibility of investigating and developing on its applicability on a large scale. To this end, different solutions are provided for the improvement of the environment.
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Pomar-Portillo, Vicenç. "Engineered nanomaterials release from nano-enabled products." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673070.
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The increased presence of nano-enabled products in multiple applications has raised concerns about its potential risks to human health and the environment. Therefore, there is a need for a responsible and coordinated approach to ensure that potential safety issues are being addressed at the same time as the technology is developing. The research presented in this PhD Thesis has the objective to contribute to the understanding of the potential human and environmental risks associated with engineered nanomaterials and nano-enabled products by generating relevant data on engineered nanomaterials released from nano-enabled products along their life cycle.
The objective has been tackled from three different perspectives: Firstly, by upgrading and refining material flow models that allow the prediction of engineered nanomaterials concentration in the environment; secondly, by generating release data from experimental simulations with multiple nano-enabled products; and thirdly, by evaluating the current research performed in Nanosafety Projects funded by the European Commission and suggesting where future research on release studies should focus.
The material flow model refinement is presented in the form of one peer-reviewed publication. In this study, a country-specific assessment of the flows to the environment from production to end-of-life of nano-Ag, -TiO2 and -ZnO within Europe is described. The MF model provided insights on potential exposure to the environment. The outcomes from the model were ENM concentrations (tonnes/km2) in different environmental compartments due to release. From these data, via realistic fate and exposure assessment, the data could be used to determine the potential risk that nano-TiO2, -ZnO and -Ag releases could pose to the environment.
The release data generation from experiments is presented by two peer-reviewed publications and five unpublished results. In the first publication, the release from a fluorescent ink containing CdTe quantum dots during inkjet printing is evaluated. In the second publication, the release mechanisms of Polyamide 6 nanocomposites under weathering conditions are assessed. Nanocomposites containing nano-SiO2, -TiO2, -ZnO, multiwalled carbon nanotubes and two nano-organoclays were included in the study. Regarding the five unpublished studies, three of them are related to the use phase: household washing of curtains containing nano-TiO2, weathering and abrasion of an asphalt coating containing nano-TiO2 and household washing of a textile incorporating nano-Ag in different forms (nanoparticles and two nanowires of different lengths). The other two unpublished studies are related to the end-of-life, both of them considering the potential leaching that occurs in landfills. One study evaluates a camping tent
containing nano-Ag and the other a printed circuit for electronics with conductive ink containing nano-Ag. . An exhaustive characterisation was done in all the cases on both starting materials (engineered nanomaterials before being incorporated in the product), in the nano-enabled products before and after the respective experiments, and also on the released materials. The main outcomes were release rates and release forms, which were included in publically accessible databases to be used by the entire nanosafety community.
The evaluation of the current research performed in Nanosafety Projects funded by the European Commission and the suggestions where future research on release studies should focus is presented in the form of one peer-reviewed publication. The purpose of analysing the nanosafety research was to provide an overview of the products studied compared to what can realistically be found in the market (i.e. the exposure relevant materials that workers, consumers and the environment may be exposed to). In addition, the inventory also provided a rich source of information from which readers with different data needs can extract their own conclusions, providing relevant insights for the nanosafety community
The combination of key information and analyses deriving from the different studies allowed the extraction of conclusions and recommendations to contribute to the understanding of the potential human and environmental risks associated with engineered nanomaterials and nano- enabled products, which is described in the discussions and conclusions section.<br>La major presència de productes amb nanomaterials en múltiples aplicacions ha suscitat preocupacions sobre els seus possibles riscos per a la salut humana i el medi ambient. Per tant, cal un enfocament responsable i coordinat per garantir que s'aborden els possibles problemes de seguretat a el mateix temps que es desenvolupa la tecnologia. La investigació presentada en aquesta tesi doctoral té com a objectiu contribuir a la comprensió dels possibles riscos humans i ambientals associats amb els nanomaterials i els productes que en continguin, mitjançant la generació de dades rellevants sobre el seu alliberament al llarg del seu cicle de vida.
L'objectiu s'ha abordat des de tres perspectives diferents: en primer lloc, mitjançant l'actualització i perfeccionament dels models de flux de materials,; en segon lloc, generant dades d'alliberament a partir d'experiments amb múltiples productes que contenen nanomaterials; i en tercer lloc, avaluant la investigació realitzada en Projectes de Nanoseguretat finançats per la Comissió Europea.
El perfeccionament del model de flux de materials es presenta mitjançant una publicació científica. En aquest estudi, es descriu una avaluació específica per a cada país Europeu dels fluxos a l'entorn, des de la producció fins al final de la vida útil de nano-Ag, -TiO2 i -ZnO.
La generació de dades d'alliberament a partir d'experiments es presenta mitjançant dues publicacions científiques i cinc resultats no publicats. Per a tots els experiments es van determinar les velocitats d'alliberament i les formes d'alliberament.
Mitjançant l'avaluació de la recerca realitzada en Projectes de Nanoseguretat finançats per la Comissió Europea s’han generat suggeriments sobre en qué hauria de centrar-se la investigació futura sobre estudis d'alliberament, el qual es presenta també mitjançant una publicació científica.
La combinació de la informació generada i l'anàlisi derivat dels diferents estudis permet l'extracció de conclusions i recomanacions que contribueixen a la comprensió dels possibles riscos humans i ambientals associats als nanomaterials i els productes que en continguin, el que es descriu a la secció de discussions i conclusions.
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Zhang, Yongbin. "Toxicological and pharmacological actions of engineered nanomaterials." Click HERE to connect, 2009. http://digital.library.okstate.edu/etd/Zhang_okstate_0664D_10173.pdf.
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Nota, Nomakhwezi Kumbuzile Constance. "Estimated environmental risks of engineered nanomaterials in Gauteng." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6809.
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Lewis, Ricky W. "TOXICITY OF ENGINEERED NANOMATERIALS TO PLANT GROWTH PROMOTING RHIZOBACTERIA." UKnowledge, 2016. http://uknowledge.uky.edu/pss_etds/77.
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Engineered nanomaterials (ENMs) have become ubiquitous in consumer products and industrial applications, and consequently the environment. Much of the environmentally released ENMs are expected to enter terrestrial ecosystems via land application of nano-enriched biosolids to agricultural fields. Among the organisms most likely to encounter nano-enriched biosolids are the key soil bacteria known as plant growth promoting rhizobacteria (PGPR). I reviewed what is known concerning the toxicological effects of ENMs to PGPR and observed the need for high-throughput methods to evaluate lethal and sublethal toxic responses of aerobic microbes. I addressed this issue by developing high-throughput microplate assays which allowed me to normalize oxygen consumption responses to viable cell estimates. Oxygen consumption is a crucial step in cellular respiration which may be examined relatively easily along with viability and may provide insight into the metabolic/physiological response of bacteria to toxic substances.
Because many of the most toxic nanomaterials (i.e. metal containing materials) exhibit some level of ionic dissolution, I first developed my methods by examining metal ion responses in the PGPR, Bacillus amyloliquefaciens GB03. I found this bacterium exhibits differential oxygen consumption responses to Ag+, Zn2+, and Ni2+. Exposure to Ag+ elicited pronounced increases in O2 consumption, particularly when few viable cells were observed. Also, while Ni2+ and Zn2+ are generally thought to induce similar toxic responses, I found O2 consumption per viable cell was much more variable during Ni2+ exposure and that Zn2+ induced increased O2 utilization to a lesser extent than Ag+. Additionally, I showed my method is useful for probing toxicity of traditional antibiotics by observing large increases in O2 utilization in response to streptomycin, which was used as a positive control due to its known effects on bacterial respiration.
After showing the utility of my method for examining metal ion responses in a single species of PGPR, I investigated the toxicity of silver ENMs (AgENMs) and ions to three PGPR, B. amyloliquefaciens GB03, Sinorhizobium meliloti 2011, and Pseudomonas putida UW4. The ENM exposures consisted of untransformed, polyvinylpyrrolidone coated silver ENMs (PVP-AgENMs) and 100% sulfidized silver ENMs (sAgENMs), which are representative of environmentally transformed AgENMs. I observed species specific O2 consumption responses to silver ions and PVP-AgENMs. Specifically, P. putida exhibited increased O2 consumption across the observed range of viable cells, while B. amyloliquefaciens exhibited responses similar to those found in my first study. Additionally, S. meliloti exhibited more complex responses to Ag+ and PVP-AgENMs, with decreased O2 consumption when cell viability was ~50-75% of no metal controls and increased O2 consumption when cell viability was <50%. I also found the abiotically dissolved fraction of the PVP-AgENMs was likely responsible for most of the toxic response, while abiotic dissolution did not explain the toxicity of sAgENMs.
My work has yielded a straightforward, cost-effective, and high-throughput method of evaluating viability and oxygen consumption in aerobic bacteria. I have used this method to test a broad range of toxic substances, including, metal ions, antibiotics, and untransformed and transformed ENMs. I observed species specific toxic responses to Ag+, PVP-AgENMs, and sAgENMs in PGPR. These results not only show the clear utility of the methodology, but also that it will be crucial to continue examining the responses of specific bacterial strains even as nanotoxicology, as a field, must move toward more complex and environmentally relevant systems.
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Agnew, Rachel Elizabeth. "The Characterization and Size Distribution of Engineered Carbon Nanomaterials." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1243362684.
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Nazemidashtarjandi, Saeed. "Interactions of Engineered Nanomaterials with the Cell Plasma Membrane." Ohio University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1617363923755762.
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Pecoraro, Roberta. "Toxicity evaluation of new engineered nanomaterials in model organisms." Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3998.
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According to the definition adopted by European Commission in 2011 a nanomaterial (NM) is a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm-100 nm (European Commission, 2011/696/EU).
NM exhibit peculiar characteristics (e.g. small size, large surface area to mass ratio, shape, surface charge, reactive surface groups, state of agglomeration) that confer them properties substantially different from those of the bulk particles of the same composition.
Due to their widespread use in the consumer and industrial products, NMs can be released into the environment and it has been raised concern of the scientists about this question (Royal Society and the Royal Academy of Engineering, 2004).
The effects that NMs have on aquatic organisms depend on their characteristics influenced by environmental parameters. NMs enter the aquatic organisms mainly through the epithelial surfaces (such as gills, skin) or direct ingestion (Moore, 2006).
After crossing the cell membrane, NMs may be stored in vesicles, mitochondria and additional organelles within epithelial cells. They may generate reactive oxygen species, oxidative stress, cytotoxicity, apoptosis and necrosis (Oberdörster et al., 2005).
Ecotoxicological tests of NMs should first consider the behaviour of NMs in the aquatic environment and the conditions that may influence aggregation state. For example, some NMs are almost impossible to disperse in water by physical methods such as sonication or stirring and may require the use of a dispersing agent. The choice of dispersant is problematic since some of the best dispersants from a chemistry point of view are also toxic to organisms.
The potential for NMs to cause oxidative injury in fish and invertebrates remains controversial. Bar-Ilan et al., 2009 showed that silver nanoparticles (AgNPs) induced almost 100% mortality in larvae of Danio rerio after acute exposure and a variety of embryonic morphological malformations were observed.
A study showed that gold nanoparticles (AuNPs) are non toxic at the employed concentrations and do not cause obvious abnormalities in developing zebrafish embryos (Asharani et al., 2010).
Zhu et al. (2009) observed effects on mortality and immobility on D. magna in the case of titanium nanoparticles (TiO2NPs) nanoparticles smaller than 20 nm.
Currently there is a lack of knowledge about long-term risks and potential mechanisms of toxicity of NMs; the industrial-scale application of engineered nanomaterials in many areas of daily life raises the question of the security of these systems because the nanodimensions are able to overcome natural barriers, resulting in potential biological damage.
The main aim of this Ph.D. Thesis was the evaluation of the potential toxic effects of several NMs on aquatic organisms used as models considering their increasing use in the product market. Short and long-term ecotoxicological assays developed, searching for specific biomarkers of exposure by immunohistochemistry, western blotting and gene expression analysis.
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Brunelli, Andrea <1984>. "Advanced physico-chemical characterization of engineered nanomaterials in nanotoxicology." Doctoral thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/4656.
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L'ampio utilizzo di nanomateriali ingegnerizzati (ENM) in svariati prodotti sta suscitando una crescente attenzione sull potenziale rischio di ENM nei confronti della salute umana e l'ambiente. Nonostante le indagini tossicologiche fin qui condotte, solo in poche di esse è stata condotta la caratterizzazione di ENM prima, durante e dopo i test tossicologici. In questa tesi, all’interno del progetto europeo EU-FP7 (ENPRA) e nazionale (PRIN 2009), è stata effettuata una caratterizzazione completa di alcuni più diffusi ENM (i.e. n-TiO2, n-ZnO, n-Ag e MWCNT). In primo luogo, sono stati aggiornati i dati di caratterizzazione primaria con ulteriori analisi; inoltre, è stata effettuata la caratterizzazione secondaria di ENM, indagando il loro comportamento in matrici ambientali. I risultati ottenuti mostrano che la stabilità di ENM è stata principalmente influenzata da agenti stabilizzanti (in mezzi biologici) e dalla concentrazione iniziale di ENM (in acque sia artificiali e reali). Inoltre, la biodistribuzione di ENM negli organi studiati è stata maggiormente influenzata dalla composizione chimica e dimensione delle particelle indagate. Sono discussi sia l'approccio di caratterizzazione proposto che l'implicazione dei risultati ottenuti.<br>The extensive use of engineered nanomaterials (ENM) in both industrial and consumer products is triggering a growing attention on the potential risk of ENM posed to human health and the environment. Despite the intensive toxicological investigations, both in vitro and in vivo, only few of them have embedded a solid characterization approach, including the study of ENM before, during and after toxicological testing.
Within EU-FP7 (ENPRA) and national (Toxicological and environmental behaviour of nano-sized titanium dioxide) projects activities, a comprehensive characterization of both inorganic (n-TiO2, n-ZnO, n-Ag) and organic (multiwalled carbon nanotubes, MWCNT) ENM was carried out, updating and adding primary characterization data, investigating particle size, shape, crystallite size, crystalline phases, specific surface area, pore volume as well as inorganic impurities of concern. Electron microscopy, X-ray diffraction, BET method and Inductively coupled plasma- mass spectrometry or optical spectroscopy were the employed techniques. With regard to the secondary characterization of ENM, the study was divided in: (a) assessing the engineered nanoparticles (ENP) behavior in biological (0.256 mg ENP/ml) as well as in real and synthetic waters (environmentally realistic concentrations: 0.01, 0.1, 1 and 10 mg n-TiO2 P25/l) over different time interval (24 h in biological media instead of 50 h in water media) to mimic duration of toxicological tests, by means of Dynamic Light Scattering (DLS), analytical centrifugation and nephelometry; (b) evaluating the ENM biodistribution in a secondary target organ (i.e. mice brain) after intratracheally instillation of ENM (0, 1, 4, 8, 16, 32, 64 and 128 ug ENM/animal tested), achieved by a microwave-assisted digestion method, followed by ICP-MS analysis, after selecting inorganic elements (i.e. Ti, Zn, Ag, Al and Co) as tracers of ENM presence in biological tissues. To investigate the ENP behavior in biological media and ENM biodistribution in mice, both dispersion protocols of the selected ENP and analytical protocols for ENM detection after toxicological testing were provided.
The study of ENP stability in biological media highlighted that the fetal bovine serum (FBS) is the main parameter affected the ENP behavior. Among biological media tested, the largest size distributions, immediately after sample preparation, were
irecorded for n-TiO2 NRCWE-003 dispersions. n-ZnO NM-111 dispersions were the most stable (12% average demixing, simulating 24 h of real sedimentation), except for Ag NM-300, originally received as dispersion (<1% average demixing). As expected, the ENP sedimentation rates investigated in the biological medium without any stabilizer (i.e. RPMI), were the highest for the whole set of ENP tested. In general, the highest sedimentation rates were recorded for n-TiO2 NM-101 and n-Ag 47MN-03 dispersions (51% average demixing, simulating 24 h of real sedimentation).
The study of the n-TiO2 P25 stability in waters showed that agglomeration and sedimentation of n-TiO2 were mainly affected by the initial concentration. Sedimentation data fitted satisfactorily (R2 average: 0.90; 0.74<R2>0.98) with a first- order kinetic equation. The settling rate constant, k, increased by approx. one order of magnitude by moving from the lowest to the highest concentration, resulting very similar especially for all dispersions at 1 (k = 8•10-6 s-1) and 10 mg/l (k = 2•10-5 s-1) n- TiO2, regardless the ionic strength and composition of dispersions.
The results from ENM biodistribution underlined that the chemical composition and the particle size were the main parameters that influenced the ENM partitioning into organs. Ti from n-TiO2 samples with the smallest particle size distribution tested (80-400 nm and 4-100 nm) and Al from MWCNT samples were the only inorganic tracers detected in mice brain.
The whole characterization approach and the implication of these results are discussed.
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Basei, Gianpietro <1987>. "Computational tools for the safety assessment of engineered nanomaterials." Doctoral thesis, Università Ca' Foscari Venezia, 2018. http://hdl.handle.net/10579/14991.
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The increasing use of engineered nanomaterials (NMs) in nano-enabled products (NEPs) has raised societal concerns about their possible health and ecological implications. Indeed, despite their clear benefits, NMs may pose environmental, health and safety (EHS) issues. In Europe, the safety of chemicals is subject to the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulation, which requires a thorough Risk Assessment along their life cycles prior to introduction on to the market. However, the heterogeneity of NMs, with respect to physicochemical properties and observed (eco)toxicological effects, makes their case-by-case information gathering for Risk Assessment unsustainable in terms of costs, time, and number of test animals. This has required the development of Integrated Approaches to Testing and Assessment (IATA) in compliance with the 3R (Replacement, Reduction, and Refinement) principles of reducing animal testing to assist industries and regulators in decision making related to the safety of NMs. It is thus essential to make the best use of the available data resources to develop robust in silico methods such as (Quantitative) Structure-Activity Relationships ((Q)SARs) and Grouping for Read-Across models as part of IATA, to inform regulatory Risk Assessment and Safe-by-Design (SbD) decision making.
In this context, the EU funded SUstainable Nanotechnology (SUN) project, aimed at combining the bottom-up development of EHS tools, knowledge and data with their top-down integration into a Decision Support System (SUNDS, https://www.sunds.gd/) for risk management of NMs.
In this thesis, the SUN project is introduced, and an overview on SUNDS and its structure is provided, focusing on the Human Health Risk Assessment (HHRA) and the Environmental Risk Assessment (ERA) modules, which are evaluated against real-world case studies. Then, the available in silico methods to predict the hazard endpoints are critically reviewed, highlighting their strengths and their limitations and proposing a roadmap for future research in this area, including the adoption of more advanced Machine Learning techniques. Finally, two novel approaches are proposed: the former combines experimental results from simple and fast techniques with multivariate statistical methods to support SbD strategies by highlighting how surface modification can affect the colloidal stability of nanoscale titanium dioxide (TiO2), while the latter uses in a promising way the Subspace Clustering as a tool for the Read-Across and the Classification of NMs, by finding clusters in different Subspaces of the source data, learning a model in these Subspaces, and applying a basic Transfer Learning by projecting the target data on the subspace.
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Kermanizadeh, Ali. "Hazard assessment of engineered nanomaterials : impacts on hepatic and renal models." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2709.
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This study was conducted as part of a large consortium (FP7 project – ENPRA) to investigate the potential hazard of a wide range of nanomaterials (one Ag, two ZnO, two MWCNTs and five TiO2) on the liver and the kidneys for the purpose of risk assessment. The in vitro C3A hepatocyte model demonstrated that Ag and ZnO NMs were consistently more potent with respect to cytotoxicity and cytokine production. In comparison the MWCNT and TiO2 nanomaterials investigated revealed relatively lower toxicity. The cytotoxicity of ZnO may be related to its solubility, but this is less likely for the Ag NMs. Urea and albumin production were measured as indicators of hepatic function. These markers were only altered by the coated and uncoated ZnO, which significantly decreased albumin production. The C3A model also showed that the NM which induced a low cytotoxicity (TiO2 and MWCNTs) generated intracellular ROS, induced oxidative stress (GSH depletion) and that an oxidative mechanism was involved in both the induction of IL8 protein production and genotoxicity. The C3A cells were demonstrated to be a very good model to investigate nanomaterial induced effects on hepatocytes when compared to primary human hepatocytes. The results also suggested that biotransformation enzymes in hepatocytes are not important in terms of determining nanotoxicology. In vivo mice models demonstrated that the instilled Ag, ZnO and positively charged TiO2 result in distal effects on the liver in the form of oxidative stress. While all NMs with the exception of the two MWCNTs instilled via the lungs caused changes in gene expression in the liver in varying degrees. The intravenous exposure of mice to the NMs resulted in a neutrophil influx into the liver. These leukocytes play an important in the initiation of the immune response to the NMs. However the NMs were not sufficient to cause any long term neutrophil mediated inflammation or damage to the liver tissue. Any changes that were observed after 24 hr post exposure in terms of leukocyte infiltration into the tissue, antioxidants status and changes in gene expression related to inflammation, oxidative stress and apoptosis had resolved 72 hr post exposure. Next, we show that Kupffer cells are very important in the liver immune response to the NMs with a significant change in the cytokine profile following the enrichment of the macrophage population. Finally, investigations using the HK-2 renal model demonstrated that ZnO and Ag NMs were consistently more potent with respect to cytotoxicity, cytokine production (IL6 and IL8) and intracellular reactive oxygen species production. These results were consistent with those observed in the hepatocyte models. We noted that short term sub-lethal exposure to the Ag and two of the TiO2 NMs (positively charged and the 94 nm TiO2) resulted in most evident DNA damage.
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Conway, Jon R. "Fate, Transport & Implications of Engineered Nanomaterials in the Terrestrial Environment." Thesis, University of California, Santa Barbara, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10011334.
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<p>The majority of the current production, use, and disposal of engineered nanomaterials (ENMs) occur in terrestrial environments, and consequently terrestrial ecosystems are and will increasingly be some of the largest receptors of ENMs at all stages of their life cycles. In particular, soil is predicted to be one of the major receptors of ENMs due to ENM-contaminated biosolid fertilizer and nanopesticide application to agricultural fields, runoff from landfills or ENM-bearing paints, or atmospheric deposition. Both agricultural and natural systems are at risk to ENM contamination via these release scenarios, which makes it necessary to understand the interactions between ENMs, soils, and soil organisms such as plants in order to predict their impacts in real-world scenarios.
Gravity-driven vertical transport of TiO2, CeO2, and Cu(OH)2 engineered nanomaterials (ENMs) and their effects on soil pH and nutrient release were measured in three unsaturated soils. ENM transport was found to be highly limited in natural soils collected from farmland and grasslands, with the majority of particles being retained in the upper 0-3 cm of the soil profile, while greater transport depth was seen in a commercial potting soil. Physical straining appeared to be the primary mechanism of retention in natural soils as ENMs immediately formed micron-scale aggregates, which was exacerbated by coating particles with Suwannee River natural organic matter (NOM).
Changes in soil pH were observed in natural soils contaminated with ENMs that were largely independent of ENM type and concentration. These changes may have been due to enhanced release of naturally present pH-altering ions (Mg2+, H+) in the soil, likely via substitution processes. This suggests ENMs will likely be highly retained near source zones in soil and may impact local communities sensitive to changes in pH or nutrient availability.
Few studies have investigated the influence of environmental conditions on ENM uptake and toxicity, particularly throughout the entire plant life cycle. Here, soil-grown plants (Clarkia unguiculata, Raphanus sativus, and Triticum aestivum) were exposed until maturity to TiO2, CeO2, or Cu(OH)2 ENMs under different illumination intensities, in different soils, and with different nutrient levels. Fluorescence and gas exchange measurements were recorded throughout growth and tissue samples from mature plants were analyzed for metal content. ENM uptake was observed in all plant species, but was seen to vary significantly with ENM type, light intensity, nutrient levels, and soil type. Light intensity in particular was found to be important in controlling uptake, likely as a result of plants increasing or decreasing transpiration in response to light.
Significant impacts on plant transpiration, photosynthetic rate, CO2 assimilation efficiency, water use efficiency, and other parameters related to physiological fitness were seen. The impacts were highly dependent on environmental conditions as well as ENM and soil type. Notably, many of these effects were found to be mitigated in soils with limited ENM mobility due to decreased uptake. These results show that abiotic conditions play an important role in mediating the uptake and physiological impacts of ENMs in terrestrial plants.
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Mudunkotuwa, Imali Ama. "Engineered metal based nanomaterials in aqueous environments: interactions, transformations and implications." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/5028.
Full textAbstract:
Nanoscience and nanotechnology offer potential routes towards addressing critical issues such as clean and sustainable energy, environmental protection and human health. Specifically, metal and metal oxide nanomaterials are found in a wide range of applications and therefore hold a greater potential of possible release into the environment or for the human to be exposed. Understanding the aqueous phase behavior of metal and metal oxide nanomaterials is a key factor in the safe design of these materials because their interactions with living systems are always mediated through the aqueous phase. Broadly the transformations in the aqueous phase can be classified as dissolution, aggregation and adsorption which are dependent and linked processes to one another. The complexity of these processes at the liquid-solid interface has therefore been one of the grand challenges that has persisted since the beginning of nanotechnology. Although classical models provide guidance for understanding dissolution and aggregation of nanoparticles in water, there are many uncertainties associated with the recent findings. This is often due to a lack of fundamental knowledge of the surface structure and surface energetics for very small particles. Therefore currently the environmental health and safety studies related to nanomaterials are more focused on understanding the surface chemistry that governs the overall processes in the liquid-solid interfacial region at the molecular level.
The metal based nanomaterials focused on in this dissertation include TiO2, ZnO, Cu and CuO. These are among the most heavily used in a number of applications ranging from uses in the construction industry to cosmetic formulation. Therefore they are produced in large scale and have been detected in the environment. There is debate within the scientific community related to their safety as a result of the lack of understanding on the surface interactions that arise from the detailed nature of the surfaces. Specifically, the interactions of these metal and metal oxide nanoparticles with environmental and biological ligands in the solutions have demonstrated dramatic alterations in their aqueous phase behavior in terms of dissolution and aggregation. Dissolution and aggregation are among the determining factors of nanoparticle uptake and toxicity. Furthermore, solution conditions such as ionic strength and pH can act as controlling parameters for surface ligand adsorption while adsorbed ligands themselves undergo surface induced structural and conformational changes. Because, nanomaterials in both the environment and in biological systems are subjected to a wide range of matrix conditions they are in fact dynamic and not static entities. Thus monitoring and tracking these nanomaterials in real systems can be extremely challenging which requires a thorough understanding of the surface chemistry governing their transformations.
The work presented in this dissertation attempts to bridge the gap between the dynamic processing of these nanomaterials, the details of the molecular level processes that occur at the liquid-solid interfacial region and potential environmental and biological interactions. Extensive nanomaterial characterization is an integral part of these investigations and all the materials presented here are thoroughly analyzed for particle size, shape, surface area, bulk and surface compositions. Detailed spectroscopic analysis was used to acquire molecular information of the processes in the liquid-solid interfacial region and the outcomes are linked with the macroscopic analysis with the aid of dynamic and static light scattering techniques. Furthermore, emphasis is given to the size dependent behavior and theoretical modeling is adapted giving careful consideration to the details of the physicochemical characterization and molecular information unique to the nanomaterials.
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Cross, Richard Kynaston. "The fate of engineered nanomaterials in sediments and their route to bioaccumulation." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/32761.
Full textAbstract:
The production of engineered nanomaterials is an emerging and rapidly expanding industry. It exploits the capacity for materials to be manufactured to present particular properties distinct from the bulk material, through tailoring of the particle size and surface functionality. This ability to fine tune particle properties at the nanoscale is responsible for the explosion in uses of engineered nanomaterials in industries as diverse as cosmetics and medicine, to “green” technologies and manufacturing. However, this increased reactivity at the nanoscale, defined as having at least one dimension < 100 nm in size, is also responsible for the increasing concern over their environmental safety. Material flows of engineered nanoparticles into the aquatic environment have been identified throughout their production, use and disposal, putting these ecosystems at potential risk of contamination. In particular, sediments are a likely sink of engineered nanomaterials in the aquatic environment due to their propensity to destabilise and settle out of suspension in natural freshwaters. An emerging body of literature has demonstrated toxicity of nanomaterials to aquatic species. In this thesis, the case is presented for using bioaccumulation as a first indicator of risk to aquatic organisms exposed to engineered nanomaterials. Using the sediment dwelling freshwater worm, Lumbriculus variegatus, this work investigates the factors which govern the bioaccumulation of cerium oxide and silver nanomaterials. It is hypothesised that the fate of these materials in sediments will be determined by their core composition, primary particle size and surface coating. A novel approach is presented to measure two biologically relevant fate parameters (persistence of particles and dissolved species in the sediment pore waters) and how particle properties affect the distribution of the nanomaterials between these phases of the sediment. This provides the context within which to interpret biological exposures assessing both the extent of uptake and how they are accumulated, whether through dietary uptake or across the skin. Understanding this route to uptake is important as the mechanism of toxicity may depend upon the point of contact of a material at the nano-bio interface. For example, a nanoparticle which comes into contact with biological material in the gut may exert a different effect upon an organism than one which is translocated directly across the skin. It is demonstrated that sediment properties determine the fate of engineered nano cerium oxide and silver to a greater extent than stabilising surfactants, with the majority of particles aggregating or associating with the solid constituents of the sediment > 200 nm in size. The dissolved fraction of the metal present in the pore waters was a better predictor of bioavailability than the persistence of particulate material < 200 nm in size, with partially soluble nanosilver being more available than insoluble cerium oxide. The route to metal nanoparticle uptake also differed with particle core, with electrostatically stabilised citrate and sterically stabilised polyethylene glycol (PEG) coated ceria available only through dietary uptake, whilst citrate and PEG coated silver was accumulated through transdermal uptake. Dynamic changes in the fate of silver nanoparticles were also observed for sterically stabilised polyvinylpyrrolidone (PVP) coated silver, resulting in the emergence of a colloidal pore water fraction of silver after 3 months aging in sediments. However, this colloidal silver was still not considered accumulated, indicating that low molecular weight species of silver, dissolving from the particle surface either during the exposure or upon contact with the worms’ surfaces was responsible for uptake of silver from the sediments. In conclusion, this work contributes towards our understanding of the factors which determine both the route and extent of biological uptake of engineered nanomaterials. It presents a novel combination of methods which allow for understanding bioaccumulation of these materials in the context of their fate and behaviour within sediments.
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Costa, Nuno Mouta Faria da. "Short term toxicity of nanomaterials in different development stages of amphibians." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14129.
Full textAbstract:
Mestrado em Toxicologia e Ecotoxicologia<br>The production of engineered nanomaterials is rising and constantly
growing. The fast advances in this industry are causing the
introduction of nanomaterials (NMs) into the environment, namely
into aquatic ecosystems. The specific properties that these new
compounds exhibit may promote higher toxicity to biota,
comparatively to their bulk counterparts. Size, charge, surface area,
aggregation index, among others, may dictate the availability and the
degree of toxicity of NMs in aquatic environments, especially when
assembled with environmental changing conditions such as pH and
temperature. Amphibians are excellent bioindicators to study the risk
associated with the release of NM into the aquatic environment, since
they inhabit a wide variety of freshwater habitats associated with
industrial contamination. The present work intended to study the
toxicity of NMs to different life stages of amphibians, concerning the
increase of global temperature that is currently taking place. In order
to achieve this, two specific goals were determined:
i) evaluate the influence of temperature in the toxicity of NMs of
hidrophobically modified polyacrylic acid (HM-PAA) to tadpoles of
Epidalea calamita and Pelophylax perezi. For this, tadpoles of E.
calamita and P. perezi were exposed to a range of six concentrations
of HM-PAA plus a control, at 20ºC and 25ºC. Results showed lethal
and sublethal toxicity of HM-PAA, but a clear pattern of temperature
influence in the toxicity of HM-PAA could not be unveiled;
ii) assess the influence of Si-NM size and temperature in the toxicity
of this NM to embryos of Pelophylax perezi. To attain this goal,
embryos of P. perezi were exposed to a range of six concentrations
of three differently sized Si-NMs (SM30-7nm, HS30-12nm, and
TM40-22nm) plus a control, at 20ºC and 26ºC. Results obtained show
lethal and sublethal toxicity caused by all the Si-NM and an increased
toxicity at higher temperatures. Furthermore, it was observed that the
NM presenting the lowest primary size exhibited the highest toxicity.<br>A produção de nanomateriais artificiais está em constante
crescimento. Os rápidos avanços nesta indústria promovem a
introdução de nanomateriais (NMs) no meio ambiente,
nomeadamente nos ecossistemas aquáticos. As propriedades
específicas que estes compostos apresentam podem promover uma
maior toxicidade comparativamente aos seus correspondentes de
tamanho não nano. Tamanho, carga, área superficial, índice de
agregação, entre outras propriedades, podem ditar o grau de
toxicidade dos NMs em ambientes aquáticos, especialmente quando
combinados com as constantes mudanças de vários parâmetros
ambientais, por exemplo pH e temperatura. Os anfíbios são
excelentes bioindicadores para estudar o risco associado à
introdução de NMs no meio aquático, uma vez que habitam uma
grande variedade de habitats de água doce potencialmente
contaminados com descargas industriais. O presente trabalho teve
como objetivo estudar a toxicidade de NMs em diferentes estágios
de vida de anfíbios, tendo em perspetiva a influência do aumento da
temperatura global que atualmente afeta o planeta Terra. A fim de
alcançar este objetivo, foram realizados dois estudos que
pretenderam:
i) avaliar a influência da temperatura na toxicidade de NMs de ácido
poliacrílico hidrofobicamente modificado (HM-PAA) para girinos de
Epidalea calamita e Pelophylax perezi. Para tal, girinos de E.
calamita e P. perezi foram expostos a uma gama de seis
concentrações de HM-PAA e a um controlo, a temperaturas de 20ºC
e 25ºC. Os resultados mostram toxicidade letal e sub-letal provocada
pelo HM-PAA, no entanto, não foi visível um padrão claro de
influência da temperatura na toxicidade deste NM;
ii) determinar a influência do tamanho de Si-NMs e da temperatura
na sua toxicidade para embriões de Pelophylax perezi. Ovos de P.
perezi foram expostos a uma gama de seis concentrações de três Si-
NPs com diferentes tamanhos (SM30-7nm, HS30-12nm, e TM40-
22nm) e a um controlo, a temperaturas de 20ºC e 26ºC. Os
resultados obtidos mostram toxicidade letal e sub-letal causadas
pelos 3 NMs e um aumento da toxicidade com temperaturas mais
elevadas. Mais ainda o NM com menor tamanho apresentou maior
toxicidade.
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Yuan, Ding. "Atomically Thin Nanomaterials for Next-Generation Energy Storage and Conversion Devices." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/405191.
Full textAbstract:
Since the fabrication of graphene, designing advanced atomically thin nanomaterials (ATMs) with few-atoms thick layers, special electronic structures, and excellent electrochemical properties for next-generation energy storage and conversion devices has attracted worldwide attention. Compared with traditional bulk materials, the ATMs exhibit several advantages: i) Their large specific surface area offers abundant active sites for ion insertion/deinsertion, and increases the contact with the electrolyte; ii) The atomic thickness of ATMs conspicuously shortens the ion diffusion pathway; iii) The distorted crystal lattice of ATMs could lead to increased electrical conductivity, and also facilitate vacancy generation, elemental doping and heterostructure construction; iv) The ATMs are regarded as an ideal 2D platform to explore the connection between electrochemical performance and electronic structures. However, they also face challenges like weak conductivity, large bandgap, and poor chemical activity. To solve these problems, various methods, including doping/phase engineering, vacancies/hole creation, and heterostructure construction have been utilized to optimize their properties. The goal of this thesis is to present a deep understanding of the impact of structural design and engineered defects on the electrochemical performance of ATMs.
In the first study, holey graphene (HG) was created through an etching method, which acted as a template for the in-situ growth of atomically thin mesoporous NiCo2O4 nanosheets, leading to a NiCo2O4-HG heterostructure. The atomic-thin thickness and porous structures of NiCo2O4-HG was beneficial for electrolyte diffusion and ions/electrons transfer, and the subsequent numerous accessible surface atoms result in improved redox pseudocapacitance. In addition, the synergistic effect between NiCo2O4 and HG produced a broad interfacial area and increased electrical conductivity, dramatically accelerating the intercalation pseudocapacitance. Both redox and intercalation pseudocapacitive energy storage are beneficial for achieving high energy and power density in lithium-ion batteries (LIBs). Consequently, the NiCo2O4@HG delivered a high specific capacity of 1103.4 mAh g-1 at 0.2 C, ~88.9% contribution from pseudocapacitance at 1 mV s-1 and ultra-long life up to 450 cycles with 931.2 mAh g-1 retention, significantly outperforming previously reported electrodes.
Vacancies engineering is an effective way to optimize the properties of ATMs. However, cation vacancies have rarely been reported for batteries because of the challenging creation process. Thus, we applied an alkaline etching strategy to produce Co vacancies (VCo) at the interface of ultra-thin Co3-xO4/graphene@CNT for highenergy/ power LIBs. The existence of VCo were confirmed by HRSTEM, XPS, and ELLS. The Co3-xO4/graphene@CNT showed a high capacity of 1688.2 mAh g-1 at 0.2 C, outstanding rate capability of 83.7% capacity retention at 1 C, excellent cycling performance (1500 cycles with a reversible capacity of 1066.3 mAh g-1), and a large pseudocapacitive contribution (86.5%) induced by VCo at the interface of Co3-xO4/graphene@CNT. Density functional theory (DFT) indicates that the VCo could significantly improve Li adsorption and provide more pathways with a lower energy barrier for Li diffusion, leading to obvious intercalation pseudocapacitive behavior and high-capacity/rate energy storage.
Inspired by the effect of VCo on the battery performance of Co3-xO4/graphene@CNT, we also created VCo on the interface of Co1-xSe2/graphene (Co1-xSe2/GE) which was utilized as anode for SIBs. The DFT result indicated that due to the VCo the Co1-xSe2/GE exhibited higher sodium adsorption energy (4.57 eV) and lower sodium diffusion barrier (~1.7 eV) which is beneficial for the intercalation and diffusion of Na+. Experimental results confirmed that the tuned electronic state of Co in Co1-xSe2/GE could result in high specific capacity (626.2 mAh g-1 at 0.2 C), outstanding rate capacity, large pseudocapacitive contribution ratio and an exceptional cycling performance superior to most CoSe2-based anodes. The outstanding energy storage performance of Co1-xSe2/GE may be due to the synergistic effect between ultrathin CoSe2 nanobelts and GE nanosheets, which could provide multiple diffusion pathways, added active sites, and lower Na+ diffusion barriers leading to excellent pseudocapacitance behaviour. This work implied that VCo could stimulate the potential of CoSe2 to facilitate the development of low-cost energy storage devices.
In addition to application in batteries, we also explored the potential of ATMs for the oxygen evolution reaction (OER). In the final work, we focused on the role of S on the OER activity of ultrathin FeCoOOH and used DFT to confirm the catalytically active centres. The results suggest the electronic states of Co could be optimized by the synergistic effect between two coordinating S and one adjacent Fe, leading to decreased binding energy of OH* (ΔEOH) while rarely changing ΔEO, thereby dramatically lowering the overpotential of the catalytic activity. Further experimental studies verified the synergistic effect between S and Fe on tuning the electronic structure of Co(OH)2, which greatly improved its catalytic activity with a small overpotential of 225.3 mV to drive to a current density of 20 mA cm-2. This work unveils the origin of the high catalytic activity of transition metal sulfides in the atomic level and provides insights into the prospect of ATMs as efficient OER electrocatalysts.
In summary, the research exhibited in this thesis indicated that defect engineering of ATMs could increase the surface active sites, provide an additional pathway for ions/electrons transfer, and increase the pseudocapacitance contribution resulting in outstanding battery performance. ATMs also showed impressive potential for electrocatalysis application. These bottom-up synthesis methods and defect engineering were also validated for other transition metal oxides/ dichalcogenides for different energy storage and conversion devices.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>School of Environment and Sc<br>Science, Environment, Engineering and Technology<br>Full Text
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Griffiths, Owen Glyn. "Environmental life cycle assessment of engineered nanomaterials in carbon capture and utilisation processes." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629663.
Full textAbstract:
CO2 is a waste product from a number of human activities such as fossil fuel power generation, industrial manufacturing processes, and transport. The rising concentration of CO2 in the atmosphere is heating the planet’s surface via the well-established greenhouse effect; a mechanism for many irreversible climate change impacts. Coupled to this is the ever-increasing global pressure over the availability and access to fossil fuel reserves; the foundations of modern society. In recognition of this CO2 is gaining renewed interest as a carbon feedstock, a changing of attitude viewing it as an asset rather than waste. Carbon capture and utilisation (CCU) technologies are attempting to make use of it. However, little quantitative assessment work has been done to assessand verify such potentials. This thesis applies the principles and framework of the life cycle assessment (LCA) - environmental management tool to early stage CO2 utilisation laboratory processes. All processes employ engineered nanomaterials (ENM) to perform this function, a material class leading the way in the challenges of efficient and feasible CO2 chemistry. The LCA contribution in this thesis acts as a measuring and a guiding tool for technology developers, in the first instance to document the cradle-to-gate impacts of a number of formed ENMs. Appreciating the net environmental benefits of ENM uptake within society has yet to be wholly established, and the unavailability of data is recognised as a major factor. The work of this thesis will thus contribute to knowledge gaps, and be informative to wider community seeking to quantify technical performance benefits of ENMs in the context of net life cycle impact burdens. Finally the actual CCU processes are assessed, initially within the confines of the laboratory but further expanded for consideration at more industrially relevant scales. The potential for sound CCU performance were found achievable under best case conditions, with net GHG impact reductions over the life cycle, and the potential for lower impact carbon products, even carbon negative. However other environmental impacts such as ozone depletion, toxic emissions and the consumption of precious metalores are impacts that require consideration in the use of such technologies.
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Dan, Mo. "THE PHARMACOKINETICS OF METAL-BASED ENGINEERED NANOMATERIALS, FOCUSING ON THE BLOOD-BRAIN BARRIER." UKnowledge, 2013. http://uknowledge.uky.edu/pharmacy_etds/21.
Full textAbstract:
Metal-based engineered nanomaterials (ENMs) have potential to revolutionize diagnosis, drug delivery and manufactured products, leading to greater human ENM exposure. It is crucial to understand ENM pharmacokinetics and their association with biological barriers such as the blood-brain barrier (BBB). Physicochemical parameters such as size and surface modification of ENMs play an important role in ENM fate, including their brain association. Multifunctional ENMs showed advantages across the highly regulated BBB. There are limited reports on ENM distribution among the blood in the brain vasculature, the BBB, and brain parenchyma.
In this study, ceria ENM was used to study the effect of size on its pharmacokinetics. Four sizes of ceria ENMs were studied. Five nm ceria showed a longer half-life in the blood and higher brain association compared with other sizes and 15 and 30 nm ceria had a higher blood cell association than 5 or 55 nm ceria. Because of the long circulation and high brain association of 5 nm ceria compared with other sizes, its distribution between the BBB and brain parenchyma was studied. The in situ brain perfusion technique showed 5 nm ceria (99%) on the luminal surface of the BBB rather than the brain parenchyma.
For biomedical applications in the central nervous system (CNS), it is vital to develop stable and biocompatible ENMs and enhance their uptake by taking advantage of their unique properties. Cross-linked nanoassemblies entrapping iron oxide nanoparticles (CNA-IONPs) showed controlled particle size in biological conditions and less toxicity in comparison to Citrate-IONPs. CNA-IONPs considerably enhanced MRI T2 relaxivities and generated heat at mild hyperthermic temperatures (40 ~ 42°C) in the presence of alternating magnetic field (AMF). Numerous researchers showed mild whole body hyperthermia can increase BBB permeability for potential brain therapeutic application. Compared to conventional hyperthermia, AMF-induced hyperthermia increased BBB permeability with a shorter duration of hyperthermia and lower temperature, providing the potential to enhance IONP flux across the BBB with reduced toxicity.
Overall, ENMs with optimized physicochemical properties can enhance their flux across the BBB into the brain with desirable pharmacokinetics, which provide great potential for diagnosis and therapy in the CNS.
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Chan, Andrea C. "The application of nanomaterials for the delivery of natural antimicrobials in engineered systems." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:9f8b7c1c-7d49-437b-9743-cb3008d89f86.
Full textAbstract:
Biofouling is the undesired biofilm formation on surfaces at a liquid interface that interferes with the affected substrate’s function. It is a ubiquitous problem in many engineered systems in industry. Biofouling causes contamination, essential damage to materials, and impedances to crucial industrial processes. These adverse effects lead to health hazards, gross increase in energy consumption, and significant decrease in overall productivity, all of which result in higher operational costs and environmentally destructive consequences. Interest in discovering effective alternatives to conventional antimicrobial agents has gained momentum. Current anti-biofouling strategies have significant disadvantages, such as the generation of toxic by-products, indiscriminate corrosion of surrounding materials and the environment, and promotion of resistance development. Alternative methods of controlling biofouling are in high demand because present-day solutions are far from sustainable. Plant secondary metabolites are promising candidates as novel biocides because they are (i) highly effective in killing microbes while being non-toxic to humans at antimicrobially active concentrations, and (ii) safer and non-damaging to the natural environment. Herein, antimicrobial efficacies of five plant-derived compounds were assessed against various species of planktonic bacteria as well as biofilms at various maturity stages. Allyl isothiocyanate (AIT) and cinnamaldehyde (CNAD) displayed the greatest inhibitory effects against all planktonic species tested. The minimum inhibitory concentration is defined as the lowest concentration of a substance that inhibits visible microbial growth, and the MBC is defined as the lowest concentration at which 99.9% of the population is killed. AIT yielded MICs of 156.25 mg/L and MBCs of 156.25 to 312.5 mg/L, and CNAD yielded MICs of 78.125 to 156.25 mg/L and MBCs of 78.125 to 312.5 mg/L. Furthermore, 312.5 mg/L AIT and 625 mg/L CNAD successfully reduced > 80% of biofilm adhesion as compared to negative controls. AIT and CNAD were therefore further evaluated extensively. Hindered by their volatile nature and immiscibility, plant secondary metabolites typically do not reach their maximum antimicrobial capacity due to low bioavailability. Thus, they would benefit from being protected and delivered in nano-sized carriers. In this study, mesoporous silica nanoparticles (MSNs) were evaluated as carriers for AIT and CNAD delivery. In one, employment of MSNs as carriers doubled the antibacterial efficacy of free form AIT and increased kill rate of free form CNAD by six times. Furthermore, free form AIT caused ~70% of 60 day-old biofilm to detach, whereas AIT-loaded MSNs essentially removed all of the biofilm. As for CNAD, its free form had no significant effect, whereas CNAD-loaded MSNs caused ~80% reduction in biofilm biomass. MSNs were further engineered to incorporate lactose pore caps to achieve specific, on-command delivery. These MSNs were designed to respond to external stimuli intelligently, with gatekeepers that degrade only in the vicinity of certain target bacteria that are able to metabolise lactose. Capped AIT-loaded MSNs reduced bacterial viability by ~85% as compared to the negative control, while capped CNAD-loaded versions reduced viability by ~40%. This stimuli-triggered MSN delivery technology would be more sustainable than current methods because resistance development would be lowered, and the delivery vehicles could be recycled and reused. Herein, the complete AIT- or CNAD-loaded, lactose-capped MSNs delivery complex proved to be an effective and environmentally conscientious system for killing unwanted bacteria.
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Tatsi, Kristi. "The biological effects of engineered nanomaterials on soil organisms : surface coating and age matter." Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/11034.
Full textAbstract:
Engineered nanomaterials (ENMs) have been increasingly used in various applications. Often, the ENMs are functionalised with a surface coating to enhance their properties. Decades of research has provided information on mostly pristine and unmodified ENMs, while ecotoxicity of coated ENMs and how their hazard changes with age in soils is still uncertain. The thesis aimed to determine the toxic effects and bioaccumulation potential of CuO ENMs and CdTe quantum dots (QDs) with different chemical coatings (carboxylate, COOH; polyethylene glycol, PEG; ammonium, NH4+) on the earthworm (Eisenia fetida), and compare the effects to their metal salt (CuSO4) or micron-sized counterpart. Then, to determine if any observed toxicity was altered after ageing the soils for up to one year. Incidental plant growth was studied in the exposure soils to maximise the scientific value of the earthworm tests. Toxic effects of CuO ENMs were also assessed in Caenorhabditis elegans exposed in liquid and soil media to understand effects of the media and method of dosing on ENM toxicity. CuO ENMs were equally toxic to earthworms, or less toxic to plants than the dissolved Cu; whereas CdTe QD ENMs were more toxic than the micron-sized CdTe QDs. There was a coating effect in both, CuO and CdTe QD ENM experiments, the -COOH coated ENMs were most toxic in the fresh soil study, while -NH4+ coated ENMs were most toxic in the aged soil study. Despite the similarities in the toxicity ranking, the biological effects exerted were different between CuO and CdTe QD ENMs. In C. elegans exposures, the ENMs were more hazardous than dissolved Cu, but ranking of ENMs depended on the media and method of dosing. The results suggest the coating effect is determined by the reactivity of the coating in a given media, and it also depends on the core of the ENMs. As such, coating and ageing effects should be considered in the risk assessment of ENMs.
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Gonzalez-Estrella, Jorge Gonzalez. "Toxicity of Engineered Nanoparticles to Anaerobic Wastewater Treatment Processes." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/347117.
Full textAbstract:
Nanotechnology is an increasing market. Engineered nanoparticles (NPs), materials with at least one dimension between 1 and 100 nm, are produced on a large scale. NPs are vastly used in industrial processes and consumer products and they are most likely discharged into wastewater treatment plants after being used. Activated Sludge is one of the most applied biological wastewater treatment processes for the degradation of organic matter in sewage. Activated sludge produces an excess of sludge that is commonly treated and stabilized by anaerobic digestion. Recent studies have found that NPs accumulate in the activated sludge; thus, there is a potential for the concentrations of NPs to magnify as concentrated waste sludge is fed into the anaerobic digestion process. For this reason, it is important to study the possible toxic effects of NPs on the microorganisms involved in the anaerobic digestion process and the approaches to overcome toxicity if necessary. The present work evaluates the toxic effect of NPs on anaerobic wastewater treatment processes and also presents approaches for toxicity attenuation. The first objective of this dissertation (Chapter III) was to evaluate the toxicity of high concentrations (1, 500 mg L⁻¹) of Ag⁰, Al₂O₃, CeO₂, Cu⁰, CuO, Fe⁰, Fe₂O₃, Mn₂O₃, SiO₂, TiO₂, and ZnO NPs to acetoclastic and hydrogenotrophic methanogens and the effect of a dispersant on the NPs toxicity to methanogens. The findings indicated that only Cu⁰ and ZnO NPs caused severe toxicity to hydrogenotrophic methanogens and Cu⁰, CuO, and ZnO NPs to acetoclastic methanogens. The dispersant did not impact the NPs toxicity. The concentrations of Cu⁰ and ZnO causing 50% of inhibition (IC₅₀) to hydrogenotrophic methanogens were 68 and 250 mg L⁻¹, respectively. Whereas the IC₅₀ values for acetoclastic methanogens were 62, 68, and 179 for Cu⁰, ZnO, and CuO-Cu NPs respectively. These findings indicate that acetoclastic methanogens are more sensitive to NP toxicity compared to hydrogenotrophic methanogens and that Cu⁰ and ZnO NPs are highly toxic to both. Additionally, it was observed that the toxicity of any given metal was highly correlated with its final dissolved concentration in the assay irrespective of whether it was initially added as a NP or chloride salt, indicating that corrosion and dissolution of metals from NPs may have been responsible for the toxicity. The second objective of this dissertation (Chapter IV) was to evaluate the Cu⁰ NP toxicity to anaerobic microorganisms of wastewater treatment processes. Cu⁰ is known to be toxic to methanogens; nonetheless, little is known about its toxic effects on microorganisms of upper trophic levels of anaerobic digestion or other anaerobic process used for nitrogen removal. This specific objective evaluated Cu⁰ NP toxicity to glucose fermentation, syntrophic propionic oxidation, methanogenesis, denitrification and anaerobic ammonium oxidation (anammox). Chapter IV showed that anammox and glucose fermentation were the least and most inhibited processes with inhibition constants (K(i)) values of 0.324 and 0.004 mM of added Cu⁰ NPs, respectively. The Ki values obtained from the residual soluble concentration of the parallel experiments using CuCl₂ indicated that Cu⁰ NP toxicity is most likely caused by the release of soluble ions for each one of the microorganisms tested. The results taken as a whole demonstrate that Cu⁰ NPs are toxic to a variety of anaerobic microorganisms of wastewater treatment processes. The third objective of this document (Chapter V) was to study the role of biogenic sulfide in attenuating Cu⁰ and ZnO NP toxicity to acetoclastic methanogens. Previous literature results and research presented in this dissertation indicated that the release of soluble ions from Cu and ZnO NPs cause toxicity to methanogens. In the past, the application of sulfide to precipitate heavy metals as inert non-soluble sulfides was used to attenuate the toxicity of Cu and Zn salts. Building on this principle, Chapter V evaluated the toxicity of Cu⁰ and ZnO NPs in sulfate-containing (0.4 mM) and sulfate-free conditions. The results show that Cu⁰ and ZnO were 7 and 14x less toxic in sulfate-containing than in sulfate-free assays as indicated by the differences in K(i) values. The K(i) values obtained based on the residual metal concentration of the sulfate-free and sulfate-containing assays were very similar, indicating that the toxicity is well correlated with the release of soluble ions. Overall, this study demonstrated that biogenic sulfide is an effective attenuator of Cu⁰ and ZnO NP toxicity to acetoclastic methanogens. Finally, the last objective (Chapter VI) of this dissertation was to evaluate the effect of iron sulfide (FeS) on the attenuation of Cu⁰ and ZnO toxicity to acetoclastic methanogens. FeS is formed by the reaction of iron(II) and sulfide. This reaction is common in anaerobic sediments where the reduction of iron(III) to iron(II) and sulfate to sulfide occurs. FeS plays a key role controlling the soluble concentrations of heavy metals and thus their toxic effects in aquatic sediments. This study evaluated the application of FeS as an approach to attenuate Cu⁰ and ZnO NP toxicity and their salt analogs to acetoclastic methanogens. Two particle sizes, coarse FeS (FeS-c, 500-1200 µm) and fine FeS (FeS-f, 25-75 µm) were synthesized and used in this study. The results showed 2.5x less FeS-f than FeS-c was required to recover the methanogenic activity to the same extent from the exposure to highly inhibitory concentrations of CuCl₂ and ZnCl₂ (0.2 mM). The results also showed that a molar ratio of FeS-f/Cu⁰, FeS-f/ZnO, FeS-f/Zn Cl₂, and FeS-f/CuCl₂ of 3, 3, 6, and 12 respectively, was necessary to provide a high recovery of methanogenic activity (>75%). The excess of FeS needed to overcome the toxicity indicates that not all the sulfide in FeS was readily available to attenuate the toxicity. Overall, Chapter VI demonstrated that FeS is an effective attenuator of the toxicity of Cu⁰ NP and ZnO NPs and their salt analogs to methanogens, albeit molar excesses of FeS were required.
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Henderson, Michael R. "Characterization of Scanning Mobility Particle Sizers For Use With Nanoaerosols." Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7166.
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The purpose of this study was to evaluate the performance of scanning mobility particle sizers in the characterization of nanoaerosols. A sampling chamber was constructed from aluminum and tempered glass, had a volume of 4.6 cubic feet, and was designed for the introduction of aerosols and dilution air, maintenance of aerosol concentration, and continuous exhaust of chamber air. Penetration and aerosol distribution tests were conducted within the chamber. An aerosol generation and measurement system comprised of nitrogen gas, BGI 3 jet Collison Nebulizer, diffusion dryer, aerosol charge neutralizer, mixing chamber, critical orifice, hygrometer, condensation particle counter, scanning mobility particle sizer, air sampling pump, air sampling cassettes, and a vacuum pump was assembled. A BGI 3 jet Collison Nebulizer was used to generate the nanoparticle aerosols. The two types of nanoparticle aerosols utilized in the experiment were salt (NaCl) and polystyrene latex (PSL) spheres. Relative humidity and temperature measurements were obtained within the chamber. Real-time, direct-reading particle measurement instruments including a condensation particle counter (CPC) (TSI, Model 3007), and three scanning mobility particle sizer (SMPS) instruments (Particle Measuring Systems, Nano-ID NPS500; TSI, NanoScan SMPS Nanoparticle Sizer Model 3910) were used for particle measurements. For each test run, two air samples were collected on membrane filters for electron microscopy (EM) analysis. Eight trials were conducted using NaCl nanoaerosols, and twelve trials were conducted using PSL spheres. The selected particle sizes for the experiments were 57 nm, 92 nm, 147 nm, and 220 nm.
For the NaCl nanoaerosol suspensions, the SMPS lines of fit were log-normally distributed and predominantly parallel. The geometric standard deviation (GSD) of these distributions was approximately 1.7, which confirms that the distributions were approximately the same. In these experiments, instrument 3 identified a higher percentage of NaCl particles within the size range intervals of the selected NaCl size parameter, and the count median diameters (CMDs) for the instrument 3 measurements were closer to the selected NaCl size parameter more often than the other instruments. This suggests that instrument 3 was more responsive than the other instruments to the selected size range and the selected NaCl size parameters. The electron microscopy (EM) lines of fit for the NaCl experiments were predominantly parallel with the SMPS lines of fit, suggesting that the log-normally distributions are similar. The GSD of EM distributions was approximately 1.8, which confirms that the distributions were approximately the same as the SMPS distributions. Results from the regression plots demonstrated that the main effects and interaction were statistically significant with a p<0.0001. The coefficient of determination, R2, for the regression lines was 0.87. The post-hoc Tukey HSD results identified a significant difference between the instrument 3 dataset, and the datasets for instruments 1 and 2.
For the PSL nanoaerosol suspensions, the SMPS lines of fit were log-normally distributed and predominantly parallel. The GSD of these distributions was approximately 1.3, which confirms that the distributions were approximately the same. In these experiments, instrument 2 identified a higher percentage of PSL particles within the size range intervals of the selected PSL size parameter, and instrument 2 CMDs were closer to the selected PSL size parameter more often than the other instruments. This suggests that instrument 2 was more responsive than the other instruments to the selected size range and the selected PSL size parameters. Results from the regression plots demonstrated that the main effects and interaction were statistically significant with a p<0.01. The coefficient of determination, R2, for the regression lines was 0.44. The post-hoc Tukey HSD test identified a significant difference between the instrument 3 dataset and the instrument 1 dataset. Potential sources of variability include solution water background contamination, surfactants in the PSL solution, and agglomeration.
The performance of all the scanning mobility particle sizers compared in these experiments was acceptable for research and field applications, but caution should be taken when comparing the measurements of SMPS, especially SMPS from different manufacturers.
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Satheesh, Srejith. "Fabrication and Validation of a Nano Engineered Glucose Powered Biofuel Cell." Thesis, KTH, Material- och nanofysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-162116.
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Fuel Cells are important forms of sustainable power generation and Biofuel Cells utilize the use of bio-compatible/biodegradable molecules as fuels. Glucose is an ideal candidate to serve this purpose. In this project, a Glucose Fuel Cell (GFC) has been fabricated using the nanomaterials developed in the lab. The skeletal system of this GFC is a three-layered structure; a Membrane Electrode Assembly (MEA) composed of carbon electrodes (anode and cathode) and a Poly Vinyl Alcohol/Poly Acrylic Acid (PVA/PAA) polymer electrolyte. Gold and Silver (Au and Ag) nanoparticles are utilized as catalyst on the anode and cathode respectively, which are prepared by the use of green chemistry practice. One of the GFC has been compacted under hot press and the other non-hot pressed. ,which led to different surface areas. For the validation of the GFC stacks, the glucose concentration was selected around biologically available levels, i.e at 400 mg/dL in both the cases. One trial on hot pressed membrane with 200 mg/dL of glucose is also studied. Short Circuit Current (SCC) and Open Circuit Voltage (OCV) were measured following which the voltages and currents were measured across load resistances. The Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) studies were carried out on the membrane while the electrodes were characterized by Scanning Electron Microscopy (SEM). UV-Vis studies were carried out on the Au and Ag nanoparticle suspension before and after impregnation of carbon cloth electrodes. Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) has been utilized to estimate the concentration and thus the number of nanoparticles adsorbed on the surface of the carbon cloth. The variations of output current with the thickness of the membranes were studied. The assembly containing the catalytic particles showed power levels ranging between 128.7 nW-332.2 nW in the glucose concentration of 400 mg/dL. Rigorous efforts are under process to scale down the power consumption of electronics to extremely low levels. GFCs could be used as power generators in such devices. The inexpensiveness of the fuel is a remarkable factor.
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May, Sarah [Verfasser]. "The effect of different engineered nanomaterials (ENMs) on DNA damage and repair pathways / Sarah May." Konstanz : KOPS Universität Konstanz, 2018. http://d-nb.info/1204005001/34.
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Bonetto, Alessandro <1987>. "Human and environmental exposure to Copper-based engineered nanomaterials (Cu-ENMs): transformation and toxicological effects." Doctoral thesis, Università Ca' Foscari Venezia, 2018. http://hdl.handle.net/10579/14989.
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The peculiar properties of engineered nanomaterials (ENMs), i.e. high surface-to-volume ratio and quantum effect, provide great opportunity for technical development of novel or improved products, but the potential risk associated with these materials requires further research work.
Unlike bulk chemicals, where the main environmental fate processes are controlled by the partitioning coefficient, nanoparticles are dynamic entities that undergo transformations depending on the chemical composition of the media in which they are dispersed (i.e. pH, ionic strength, organic matter and suspend particulate matter).
This Ph.D. thesis work focused on the characterization and transport and fate of copper based nanoparticles (Cu-ENMs) i.e. nano CuO and Cu2CO3(OH)2. These materials are widely used in wood preservation, in paints formulation and in antibacterial products because of the recognized efficiency in killing a range of microorganisms. Both distribution and dissolution of Cu-ENMs in biological and environmental media have been studied by using a combination of analytical techniques such as DLS (Dynamic Light Scattering), TEM (Transmission Electron Microscopy), sp-ICP-MS (single particle Inductively Coupled Plasma-Mass Spectrometry) and CSA (Centrifugal Separation Analysis).
The results obtained so far can be helpful to elucidate the dynamic equilibria between Cu-ENMs and environmental or biological media. Furthermore, a methodological approach to detect and quantify Cu-ENMs in biological tissues coming from toxicological tests was developed by combining different analytical techniques. The overall experimental activity led to the draft of three manuscripts that are discussed in detail in this thesis.
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Bhosale, R. K. "Engineered metal oxide and chalcogenide nanomaterials for sensitized solar cells and solar photoelectrochemical water splitting." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2015. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2038.
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ACOSTA, LEÓN ADRIANA Lucía. "CRITICAL APPRAISAL AND SYSTEMATIC REVIEW OF HEALTH EFFECTS OF CARBON-BASED NANOPARTICLES AND NANOMATERIALS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1147715728.
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Sweeney, Sinbad. "Differential reactivity of engineered nanomaterials with human alveolar epithelium and macrophages in vitro : importance of physicochemistry." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/26221.
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There is a vast range of diverse consumer applications for engineered nanomaterials (ENM). Commercially, titanium dioxide nanoparticles (nano-TiO2) and carbon nanotubes (CNT) are two of the most popular ENMs. Appreciating the overt vulnerability of the lung to ENM occupational and consumer exposure, we studied the biointeraction of these ENMs with cells of the alveolar unit. We hypothesised that the bioreactivity of nano-TiO2 and CNTs with cells of the alveolar unit depends on the physicochemical properties of the ENM. Transformed human alveolar type-I-like epithelial cells (TT1) and primary human alveolar type-II epithelial cells (ATII) and alveolar macrophages (AM), in mono- and co-culture, were exposed to concentrations of ENMs before probing for cytotoxicity, apoptosis, oxidative stress, glutathione activity, inflammatory mediator release, kinase signal transduction and gene transcription. With TT1 cells, we found that ENM crystalline phase is important in cellular reactivity; predominantly rutile and pure rutile nano-TiO2 induced a greater pro-inflammatory response from exposed TT1 cells than their pure and mixed anatase counterparts. The dynamic pro-inflammatory mediator release from TT1 cells, induced by nano-TiO2 exposure, was accompanied by concomitant changes in oxidative stress and modified glutathione activity. Assessing CNTs, we found that shorter CNTs (~0.6 m in length, 15nm in diameter) induced significantly greater pro-inflammatory mediator release from TT1 and ATII cells when compared to longer CNTs. Conversely, AMs showed greater reactivity following exposure to longer CNTs (~20 m in length, 15nm in diameter), releasing greater amounts of pro-inflammatory mediators when compared to shorter CNTs; these responses were associated with kinase signal transduction. Mechanisms of ENM reactivity with TT1 cells were further elucidated using transcriptomics, where a number of common and unique gene transcription responses were identified. In conclusion, we have critically shown that ENM interactions with alveolar cells depend on the physicochemical properties of the particular ENM, and the cell type involved.
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Samutrtai, Pawitrabhorn. "Ecotoxicity of engineered nanomaterials and the pathway of toxic effects in an environmental model, Caenorhabditis elegans." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3174.
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This thesis examined the adverse effects of engineered nanomaterials (NMs) and their potential mechanisms of toxicity. The research focussed on the toxicity of NMs and their dissolved ions, as well as bulk particles (larger size), if applicable, in the nematode, Caenorhabditis elegans. The physicochemical properties of chosen NMs were characterised using various techniques. The toxicity of NMs regarding their ability to kill nematodes was concentration-dependent. The dissolved ions of each type of NM were be the most toxic form. On the other hand, the mortality of nematodes was not observed when they were exposed to CuO NMs and bulk particles, which led to the decision to discontinue their study. The toxicity of AgNMs regarding the inhibition of reproduction was also in a concentration-dependent manner. Moreover, the concentrations inducing a decrease in the number of progeny were lower than those used in the mortality test, which suggested reproduction to be a more sensitive endpoint. The induction of oxidative stress, which was investigated by determination of reactive oxygen species (ROS) and related enzymes, was studied when nematodes were exposed to all silver substances. Nevertheless, there were differences observed across the different strains of nematodes. The initiation of apoptosis was examined by visualisation and determination of apoptotic proteins. However, induction of apoptosis was not observed in the testing conditions used in this thesis. The studies of transcriptome and proteome of nematodes treated with spherical AgNM, JRCNM03002a (previously NM300K) revealed that genes and proteins involved in ribosome and protein synthesis were mostly affected by the exposure to JRCNM03002a. However, time of exposure had an impact on the pathways of toxicity. The expression of genes and proteins in the pathways of oxidative stress were altered significantly within 30 minutes of exposure, while these pathways were not involved in 24 hours of exposure. In conclusion, engineered NMs, especially AgNMs, can trigger adverse effects in C. elegans. Although it was proven that the pathway of oxidative stress was related to the observed toxicity, the initiation of apoptosis was not established in the conditions used in this study.
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Townsend, R. L. "Environmental nanodetector : development of a novel method for the detection of engineered nanomaterials in the environment." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/809907/.
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Airborne particulate matter, both in the workplace and the environment, has been linked to adverse health effects, this in turn has led to the establishment of legislation stipulating exposure limits. Advances in technology, and associated increased use of nanomaterials means that such regulations and associated monitoring remain highly relevant. Monitoring techniques used for airborne particulates are costly, bulky and insensitive to low to medium exposure to nanomaterials. Capacitance based sensors, detecting changes in electrical impedance due to the presence of nanomaterials have been developed in this work. Capacitive interdigitated electrodes integrated with nanoparticulate trapping structures have been designed and manufacturing techniques suitable for mass manufacture have been evaluated and developed. Photolithographic and inkjet printing based methods for manufacturing electrodes were evaluated, identifying inkjet printing as the most appropriate technique, providing good reproducibility, ease of fabrication and the ability to rapidly tailor electrode structures to provide different capabilities. It was found that higher sensitivities were obtained when gap widths between electrodes decreased. Two trapping layers were evaluated, columnar Zinc oxide with pore sizes of 10nm to 170nm, and porous polystyrene with sizes of 10µm to 50µm. Whilst offering small pore sizes, potentially allowing the trapping and detecting of a smaller particle size distribution, under test conditions zinc oxide structures were shown to be too fragile to survive real life test events. Porous polystyrene structures were shown to have lower selectivity trapping all particles between 20-200nm, however these trapping structures were shown to withstand real life test events. Analytical modelling has shown good agreement with experimental test results and has been used to predict the devices response to different nanomaterials offering the potential that the capacitance based sensors could also be used to differentiate between different nanomaterials.
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Wang, Yifang. "Pulmonary toxicity assessment following aerosolization of engineered nanomaterials using an in vitro air-liquid interface method." Thesis, University of Iowa, 2019. https://ir.uiowa.edu/etd/7044.
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Although there are over 1,600 Engineered Nanomaterials (ENMs)-containing consumer products available, our understanding of ENM safety is still limited. Airborne ENMs can readily enter the human body through inhalation potentially leading to many adverse health effects such as cardiovascular and pulmonary diseases. The conventional in vitro submerged cell culture method was developed decades ago and has been widely used as a fast screening method to elucidate cellular toxicity upon exposure to hazardous materials; however, it has many limitations compared with the in vivo models. Our group has previously utilized and validated an integrated low flow system capable of generating and depositing airborne nanoparticles (NPs) directly onto cells at an air-liquid interface (ALI) condition, and our results confirmed that this exposure system produced reproducible toxicological data for ENMs including gold (Au), 16% silver coated onto silica (16% Ag-SiO2), and copper oxide (CuO). To further improve this ALI method for an even closer representation of the in vivo model, a co-culture model containing three cell lines (A549, THP-1 differentiated macrophages, and EA.hy 926) was established and validated for testing ENMs toxicity. The co-culture model was exposed to 16% Ag-SiO2 and CuO NPs under the same protocol (4 h ALI exposure with a concentration of 3.5 mg/m3) as monoculture (A549 only) for comparison. Toxicity was assessed by measuring cell viability, reactive oxygen species (ROS) production, lactate dehydrogenase (LDH) release, and interleukin (IL) 8 level. Results showed that 16% Ag-SiO2 NPs induced higher ROS generation, and CuO NPs produced a significant level of proinflammatory response compared with monoculture. In addition, the co-culture model exhibited a similar response with the primary human bronchial epithelia cell line (HBEC) in terms of ROS and IL-8 responses after CuO NPs exposure, suggesting a more advanced refinement of the conventional model for in vitro inhalation study.
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Davidson, Sarah E. "Alternative Approach to Dose-Response Modeling of Toxicogenomic Data with an Application in Risk Assessment of Engineered Nanomaterials." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627666554729205.
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Ha, Dat Thinh. "Developing a New Sensing Technology for Double-Stranded DNA Detection Utilizing Engineered Zinc Finger Proteins and Nanomaterials." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/3079.
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A specific double-stranded DNA sensing system is of great interest for diagnostic and other biomedical applications. Zinc finger domains, which recognize double-stranded DNA, can be engineered to form custom DNA-binding proteins for recognition of specific DNA sequences. As a proof of concept, a sequence-enabled reassembly of TEM-1 β- lactamase system (SEER-LAC) was previously demonstrated to develop zinc finger protein (ZFP) arrays for the detection of a double-stranded bacterial DNA sequence. Here, we implemented the SEER-LAC system to demonstrate the direct detection of pathogenspecific DNA sequences present in E. coli O157:H7 on the lab-on-a chip. ZFPs customdesigned to detect shiga toxin in E. coli O157:H7 were immobilized on the cyclic olefin copolymer (COC) chip, which can function as a non-PCR based molecular diagnostic. Pathogen-specific double-stranded DNA was directly detected by engineered ZFPs immobilized on the COC chip, providing a detection limit of 10 fmole of target DNA in colorimetric assay. Therefore, in this study, we demonstrated a great potential of ZFP arrays on the COC chip for further development of a simple and novel lab-on-a chip technology for detection of pathogens.
Antibiotic resistance is a serious, and rapidly growing global threat. Here, we designed a novel screening method to detect antibiotic resistance genes (ARGs) in bacteria using a graphene oxide-based biosensor utilizing engineered ZFPs. Two-dimensional
graphene oxide (GO) sheet possesses unique electronic, thermal, and mechanical properties. The quenching ability of GO can create novel methods for detection of biomolecules. Our approach utilizes quenching of fluorescence signal by GO in the absence of target ARGs, but restoring the signal in the presence of target ARGs. Quantum dot (QD)- labeled ZFP can bind to GO via stacking interactions of aromatic and hydrophobic residues in conjunction with hydrogen bonding interaction between hydroxyl or carboxyl groups of GO and hydroxyl or amine groups of the protein. Due to fluorescence resonance energy transfer (FRET) between QD and GO when they are in close proximity, fluorescence signal of QD-labeled ZFP is expected to be quenched. In the presence of target DNA, the bound DNA-protein complex is released from GO, restoring the fluorescence signal.
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Hardas, Sarita S. "INVESTIGATIONS OF OXIDATIVE STRESS EFFECTS AND THEIR MECHANISMS IN RAT BRAIN AFTER SYSTEMIC ADMINISTRATION OF CERIA ENGINEERED NANOMATERIALS." UKnowledge, 2012. http://uknowledge.uky.edu/chemistry_etds/7.
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Advancing applications of engineered nanomaterials (ENM) in various fields create the opportunity for intended (e.g. drug and gene delivery) or unintended (e.g. occupational and environmental) exposure to ENM. However, the knowledge of ENM-toxicity is lagging behind their application development. Understanding the ENM hazard can help us to avoid potential human health problems associated with ENM applications as well as to increase their public acceptance. Ceria (cerium [Ce] oxide) ENM have many current and potential commercial applications. Beyond the traditional use of ceria as an abrasive, the scope of ceria ENM applications now extends into fuel cell manufacturing, diesel fuel additives and for therapeutic intervention as a putative antioxidant. However, the biological effects of ceria ENM exposure have yet to be fully defined. Both pro-and anti-oxidative effects of ceria ENM exposure are repeatedly reported in literature. EPA, NIEHS and OECD organizations have nominated ceria for its toxicological evaluation. All these together gave us the impetus to examine the oxidative stress effects of ceria ENM after systemic administration.
Induction of oxidative stress is one of the primary mechanisms of ENM toxicity. Oxidative stress plays an important role in maintaining the redox homeostasis in the biological system. Increased oxidative stress, due to depletion of antioxidant enzymes or molecules and / or due to increased production of reactive oxygen (ROS) or nitrogen (RNS) species may lead to protein oxidation, lipid peroxidation and/or DNA damage. Increased protein oxidation or lipid peroxidation together with antioxidant protein levels and activity can serve as markers of oxidative stress.
To investigate the oxidative stress effects and the mechanisms of ceria-ENM toxicity, fully characterized ceria ENM of different sizes (~ 5nm, 15nm, 30nm, 55nm and nanorods) were systematically injected into rats intravenously in separate experiments. Three brain regions (hippocampus, cortex and cerebellum) were harvested from control and ceria treated rats after various exposure periods for oxidative stress assessment. The levels of oxidative stress markers viz. protein carbonyl (PC), 3-nitrotyrosine (3NT), and protein bound 4-hydroxy-2-trans-nonenal (HNE) were evaluated for each treatment in each control and treated rat organ. Further, the levels and activities of antioxidant proteins, such as catalase, glutathione peroxidase (GPx), glutathione reductase (GR), super oxide dismutase (SOD), were measured together with levels of heat shock proteins heme oxygenase -1 and 70 (HO-1 and Hsp-70). In addition, the levels of pro-inflammatory cytokines IL-1β, TNF-α, pro-caspase-3, and autophagy marker LC-3A/B were measured by Western blot technique. In agreement with the literature-proposed model of oxidative stress hierarchy mechanism of ENM-toxicity, the statistical analysis of all the results revealed that the ceria ENM-induced oxidative stress mediated biological response strongly depends on the exposure period and to some extent on the size of ceria ENM. More specifically, a single intravenous injection of ceria ENM induced tier-1 (phase-II antioxidant) response after shorter exposure periods (1 h and 20 h) in rat brain. Upon failure of tier-1 response after longer exposure periods (1 d to 30 d), escalated oxidative stress consequently induced tier-2 and tier-3 oxidative stress responses. Based on our observations made at chronic exposure period (90 d) after the single i.v. injection of ceria ENM, we could extend the model of oxidative stress hierarchy mechanisms for ceria-ENM-induced toxicity. Considering the evaluation of all the oxidative stress indices measured in 3-brain regions, oxidative stress effects were more prominent in hippocampus and the least in cerebellum, but no specific pattern or any significant difference was deduced.
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Ma, Yanjun. "Fate and Impacts of Contaminants of Emerging Concern during Wastewater Treatment." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/56633.
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The purpose of this dissertation was to broadly investigate the fate of antibiotic resistance genes (ARGs) and engineered nanomaterials (ENMs) as representative contaminants of emerging concern in wastewater treatment plants (WWTPs). WWTPs may have their performance impacted by ENMs and may also serve as a reservoir and point of release for both ENMs and ARGs into the environment. Of interest were potential adverse effects of ENMs, such as stimulation of antibiotic resistance in the WWTP, toxicity to microbial communities critical for WWTP performance, and toxicity to humans who may be exposed to effluents or aerosols containing ENMs and their transformation products.
Response of nine representative ARGs encoding resistance to sulfonamide, erythromycin and tetracycline to various lab-scale sludge digestion processes were examined, and factors that drove the response of ARGs were discussed. Mesophilic anaerobic digestion significantly reduced sulI, sulII, tet(C), tet(G), and tet(X) with longer solids retention time (SRT) exhibiting a greater extent of removal. Thermophilic anaerobic digesters performed similarly to each other and provided more effective reduction of erm(B), erm(F), tet(O), and tet(W) compared to mesophilic digestion. Thermal hydrolysis pretreatment drastically reduced all ARGs, but they generally rebounded during subsequent anaerobic and aerobic digestion treatments. Bacterial community composition of the sludge digestion process, as controlled by the physical operating characteristics, was indicated to drive the distribution of ARGs present in the produced biosolids, more so than the influent ARG composition.
Effects of silver (nanoAg), zero-valent iron (NZVI), titanium dioxide (nanoTiO2) and cerium dioxide (nanoCeO2) nanomaterials on nitrification function and microbial communities were examined in duplicate lab-scale nitrifying sequencing batch reactors (SBRs), relative to control SBRs received no materials or ionic/bulk analogs. Nitrification function was only inhibited by high load of 20 mg/L Ag+, but not by other nanomaterials or analogs. However, decrease of nitrifier gene abundances and distinct microbial communities were observed in SBRs receiving nanoAg, Ag+, nanoCeO2, and bulkCeO2. There was no apparent effect of nanoTiO2 or NZVI on nitrification, nitrifier gene abundances, or microbial community structure. A large portion of nanoAg remained dispersed in activated sludge and formed Ag-S complexes, while NZVI, nanoTiO2 and nanoCeO2 were mostly aggregated and chemically unmodified. Thus, the nanomaterials appeared to be generally stable in the activated sludge, which may limit their effect on nitrification function or microbial community structure.
Considering an aerosol exposure scenario, cytotoxicity and genotoxicity of aqueous effluent and biosolids from SBRs dosed with nanoAg, NZVI, nanoTiO2 and nanoCeO2 to A549 human lung epithelial cells were examined, and the effects were compared relative to outputs from SBRs dosed with ionic/bulk analogs and undosed SBRs, as well as pristine ENMs. Although the pristine nanomaterials showed varying extents of cytotoxicity to A549 cells, and gentoxicity was observed for nanoAg, no significant cytotoxic or genotoxic effects of the SBR effluents or biosolids containing nanomaterials were observed.
Studies presented in this dissertation provided new insights in the fate of ARGs in various sludge digestion processes and ENMs in nitrifying activated sludge system in lab-scale reactors. The study also yielded toxicity data of ENMs to biological wastewater treatment microbial communities and human lung cells indicated by a variety of toxicity markers. The results will aid in identifying appropriate management technologies for sludge containing ARGs and will inform microbial and human toxicity assessments of ENMs entering WWTPs.<br>Ph. D.
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Cinelli, Marco <1986>. "Risk Assessment of Engineered Nanomaterials. Case Study: A Weight-of-Evidence based Exposure Model for Ranking and Prioritization of Occupational Exposure Scenarios to Nano-Titanium Dioxide and Carbon Nanomaterials." Master's Degree Thesis, Università Ca' Foscari Venezia, 2012. http://hdl.handle.net/10579/1629.
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Il lavoro di tesi consiste in una prima parte dedicata all'analisi delle attività di standardizzazione portate avanti dalle principali organizzazioni internazionali, quali l'organizzazione internazionale per la normazione (ISO) e l'organizzazione per la cooperazione e lo sviluppo economico (OECD), nell'ambito della valutazione di rischio dei nanomateriali di sintesi. La seconda parte è analitica e consiste nello sviluppo di un modello di esposizione basato sull'approccio Weight of Evidence (WoE) finalizzato a classificare e prioritizzare scenari di esposizione occupazionale a nano biossido di titanio e nanomateriali in carbonio.
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Garrison, Elizabeth F. "Nanotoxicity of oxide-derived engineered nanomaterials : impact on cell viability and function, with conventional assays and evaluation of novel eicosanoid profiling." Thesis, University of the Highlands and Islands, 2016. https://pure.uhi.ac.uk/portal/en/studentthesis/nanotoxicity-of-oxidederived-engineered-nanomaterials(2ac60c4a-f766-404e-81e9-77354afa20bc).html.
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Epidemiological studies highlight a direct association between the decline in respiratory health of the human population and increased environmental ultrafine particulate (UFP) exposure. This evidence, coupled with research identifying shared characteristics and toxicity between UFP and engineered nanomaterial (ENM), suggests that increased levels of ENM associated with the nanotechnology revolution could have a detrimental effect on human health. Although the link between respiratory disease and air pollution is well-established, toxicological data for ENM is limited. Current methods for the assessment of particle toxicity utilise a combination of both in vitro assays and in vivo animal testing. In some cases, these conventional assays provide unreliable results on account of nanoparticle interference. In this thesis, assays were undertaken to more fully understand the impact of a panel of ENMs on alveolar epithelial cell function and survival, as well as to assess the potential value of an alternative method for nanotoxicological screening. Eicosanoid profiling was used to assess both toxicity and inflammatory markers associated with a panel of ENMs, this technique is novel for the use in testing of ENM and the results show it has potential to be introduced/applied as an effective tool to predict a broad spectrum of detrimental effects of ENM in lung function. Submerged A549 cells, were used as a model of lung epithelial cells throughout. The secondary cell line is commonly used in in vitro research to examine the effect of toxins on respiratory health, specifically the alveolar region. A panel of ENM (SiO2, TiO2, NiO, ZnO and CuO) were selected to span from the benign to the highly toxic. ENM prepared in suspension were applied to the cells at 100cm2/mL for 24 h. This doctoral thesis focused on addressing the following aims: 1. To assess whether metallic ENM of differing chemical composition damage the cell membrane and/or mitochondria. 2. To determine whether ENM induce mitochondrial dysfunction through delivery or over-production of harmful reactive oxygen species (ROS) and, if so, to determine whether mitochondrial dysfunction results in activation of apoptosis. 3. To ascertain whether ENM alter the release of lipid inflammatory mediators using eicosanoid profiling. Mitochondrial function and membrane integrity assays revealed that CuO and ZnO induced mitochondrial dysfunction (~ 100% reduction in mitochondrial function), and promoted cell death (85 ± 7.5% cell lysis, ***P<0.001), respectively, when compared to control. In addition, superoxide production was increased by TiO2 alone (~ 100% increase, 0.0394 ± 0.0081 AU, **P<0.01), creating a discrepancy between assays. Analysis also revealed that metallic ENMs, specifically ZnO and CuO, significantly increased the production of prostaglandin E2 (~ 50%, 828 ± 119pg/sample, **P<0.01) and ~ 100%, 1439 ± 248pg/sample, ***P< 0.001), a pro-inflammatory eicosanoid, and elevated generation of a range of hydroxy-eicosatetraenoic acids (HETEs), suggesting induction of lipid peroxidation by these oxide derived ENMs. In conclusion, through the use of in vitro assays and eicosanoid analysis it was determined that ZnO and CuO ENM induce cell damage and death. However, although traditional in vitro assays are able to identify highly toxic ENM from the rest, they lack the ability to identify more subtle changes and, in some cases, are unreliable. By contrast, eicosanoid profiling has the ability to provide more detailed information regarding generation of both pro- and anti-inflammatory mediators, as well as oxidative stress, whilst avoiding the issues that are encountered through the use of current in vitro tests.
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Rampley, Cordelia P. N. "Assessing the risk and consequence of engineered nano-scale zinc oxide in phytological and bacterial systems." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:423fcb1d-de11-42e4-90d3-f0767623447b.
Full textAbstract:
With the increased usage and production of engineered nanoparticles (ENPs), entry into the environment and hence contact with plant root systems is inevitable. Nano zinc oxide (nZnO) is widely used in commercial products, such as sunscreens, paints and coatings due to its high antimicrobial properties and wide electrical band-gap. Disposal down drains and into greywater leads to particle entry into the environment via waste water systems. Here, ENPs could potentially interact with plant root systems, which may lead to uptake, translocation and accumulation within plant tissues, and in the case of edible crops have consequences on human health. This study aimed to identify mechanisms of toxicity by employing whole-cell biosensors in conjunction with model bacteria and plant species. Furthermore, zeta potential (ZP), particle size, reactive oxygen species (ROS) release and solubility of the particles were determined and linked to both plant and bacterial toxicity. In Escherichia coli bacteria, it was demonstrated that growth inhibition from nano-scale ZnO treatment was similar to that from the bulk-scale ZnO and ionic zinc treatments, with the concentrations leading to 50 % inhibition (IC50) demonstrated to be 251, 282 and 298 mg/L for bulk, nano-scale and ZnSO4, respectively. It was demonstrated that the mode of nZnO toxicity in E. coli was bacteriostatic rather than bacteriotoxic. In barley plants, biomass was negatively impacted by up to 50 %, and significantly more zinc was able to enter root tissues as a result of hydroponic nZnO treatment, with 47 mg/L zinc detected in root tissues after 7 days treatment with 500 mg/L nZnO. Comparison of particle characteristics revealed that ROS, solubility, ZP, size and concentration were involved in toxicity, with ZP (charge) identified as a key parameter in both plant and bacterial toxicity.
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Garcia, Rodriguez Alba. "The applicability of in vitro models of the intestinal barrier for the risk assessment of engineered nanomaterials used as food additives." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/669883.
Full textAbstract:
Los avances en el campo de la nanotecnología han permitido desarrollar una gran diversidad de nanomateriales sintetizados artificialmente (NMs), los cuales presentan nuevas y prometedoras aplicaciones en diversas industrias. Debido a sus exclusivas propiedades, los NMs son utilizados en la comida o envoltorios de comida como mejora de textura, color, sabor, estabilizador, etc.
A pesar de sus propiedades innovadoras, existe un aumento en la preocupación sobre si las nanopartículas (NPs) de dióxido de titanio (TiO2) puedan llegar a producir efectos adversos en la salud humana. La Agencia Internacional para la Investigación del Cáncer (IARC) clasificó el TiO2 como posible carcinógeno humano (grupo 2B) debido a suficientes evidencias científicas indicando que las NPs de TiO2 pueden causar cáncer de pulmón a través de su inhalación. Sin embargo, en el mismo informe no se obtuvo resultados concluyentes respecto a la exposición de dichas NPs por vía oral debido a la falta de ensayos toxicológicos e información. Es por eso que el objetivo de la presente Tesis es estudiar de manera in vitro los efectos, factores y mecanismos biológicos que la exposición a NPs metálicas puedan causar en el epitelio del intestino delgado humano.
Para este propósito, se desarrolló por primera vez en nuestro laboratorio un modelo epitelial in vitro que mimetiza el intestino delgado humano. En nuestro primer estudio, se definieron y caracterizaron condiciones de cultivo del ya descrito modelo, Caco- 2/HT29/Raji-B. Según nuestros resultados en los estudios de integridad y permeabilidad, confirmamos que la mejor ratio de células Caco-2 (enterocitos) y HT29 (células calciformes) era 90:10, respectivamente. Paralelamente se detectó la inducción de células presentadoras de antígenos o también conocidas cómo células M, y se propuso un listado de genes cómo marcadores para bio-monitorizar la correcta diferenciación celular y formación de la barrera intestinal in vitro. Finalmente se testó la funcionalidad de nuestro modelo epitelial in vitro exponiéndolo durante 24 h tanto a NPs de TiO2 como de SiO2. Utilizando microscopía laser confocal se demostró que las NPs de TiO2 podrían conllevar efectos adversos en el epitelio intestinal ya que tienen la capacidad de internalizar en las células, llegando incluso, a entrar en contacto con el núcleo celular.
Debida a la gran diversidad de NMs que actualmente se pueden sintetizar artificialmente, y a que cada uno de ellos puede presentar propiedades distintas y por ende afectar de forma diferente sobre la salud humana, el segundo objetivo de la presente Tesis fue valorar los efectos de tres formas distintas de TiO2 (nano-esferas, nano-óvalos i nano-filamentos) utilizando el modelo intestinal Caco-2/HT29. Nuestros resultados demostraron que las tres formas de TiO2 son capaces de desestabilizar el epitelio intestinal, cruzar la cubierta de mucosa, e internalizar en las células hasta alcanzar al núcleo celular. Teniendo en cuenta las imágenes obtenidas con microscopía láser confocal, se demostró que tanto las nano-esferas cómo los nano-óvalos traspasan la barrera intestinal intracelularmente mientras que los nano-filamentos lo hacen por vía paracelular. Finalmente, utilizando el ensayo del cometa, detectamos que las tres NPs produjeron un leve pero estadísticamente significativo daño genotóxico general pero no daño genotóxico oxidativo.
Por último, el tercer estudio se llevó a cabo en el departamento de Ingeniería Biomédica de la Universidad de Binghamton (Binghamton, NY, USA) con el propósito de una mención internacional de la presente Tesis. Puesto que la absorción de nutrientes es una de las principales funciones del intestino delgado, en este estudio se evaluó la actividad de tres enzimas digestivas (Fosfatasa Alcalina Intestinal, Aminopeptidasa-N y la bomba de sodio/potasio) tras exponer el modelo Caco-2/HT29-MTX a NPs de TiO2 y SiO2. Con el fin de simular estrictamente las condiciones reales del tracto gastrointestinal humano, las NPs fueron digeridas de manera artificial simulando el proceso de digestión humano (boca, estómago, intestino), y co-cultivadas con bacterias comúnmente encontradas en el primer segmento del intestino delgado humano, el duodeno. Concretamente se utilizaron el comensal grampositivo Lactobacillus rhamnosus GG, conocido por su actividad probiótica, y el oportunista gramnegativo Escherichia coli NCTC 9001. En este estudio se observó que la presencia de ambas bacterias en el modelo in vitro Caco-2/HT29-MTX, disminuía los efectos adversos de las NPs sobre la actividad enzimática del epitelio.<br>Nano-technological approaches are allowing the development of deliberately
engineered nanomaterials (ENMs), presenting promising new applications for many
industrial fields. Especially, ENMs possess unique properties and novel uses in food or
food packaging materials such as the enhancement of texture, colour, flavour, nutrient
stability and food packaging safety.
Despite their innovative properties, there is an increasing concern about the
possibility that human exposure to TiO2NPs may lead to significant adverse health
effects. The International Agency for Research on Cancer (IARC) classified TiO2 as a
human carcinogen group 2B because there was enough evidence that nano-TiO2 may
cause lung cancer by inhalation. Although oral exposure was also debated by IARC,
the final report was inconclusive due to non-existing standardized procedures for nano-
TiO2 risk assessment. Due to the potential adverse effects of this ENMs and the lack of
information regarding toxicological aspects over the oral exposure, in this Thesis we
have carried out in vitro studies on the biological effects of TiO2NPs.
For the aforementioned purpose, we set up and characterized, for the first time in
our laboratory, an epithelial in vitro model that closely mimics the human small
intestine. Thus, in our first study, we defined the best culture conditions for the alreadydescribed
model, Caco-2/HT29/Raji-B. From our integrity and permeability findings, we
confirmed that the best Caco-2/HT29 cell ratio is 90:10, respectively, as TEER values,
paracellular LY permeability and the mucus shed formed correlated well with other
studies. We also were able to detect the induction of M-like cells by TEM. Moreover, in
order to monitor the proper barrier formation, we proposed a set of genes related to the
cell junctional complexes, brush border enzymes, mucus shed components and M-cell
markers. Finally, we tested the goodness of our epithelial in vitro model by exposing it
to both TiO2NPs and SiO2NPs for 24 h. Our confocal results evidenced the potential
adverse effects of TiO2NPs and SiO2NPs on the intestinal epithelium, as NPs
internalization and NPs-cell nucleus interaction were observed.
Because of the heightened interest in the identification, validation and
standardization of the effects associated to exposures to new ENMs, our second study
aimed to assess the effects of three different shapes of TiO2NPs (spheres, rods and
wires) on the Caco-2/HT29 barrier. Our results demonstrated that the three types of
TiO2NPs have the ability to impair the membrane’s integrity, translocate through the
mucus shed and internalize in the cells, reaching the nucleus. Taking into account our
confocal images results, we hypothesize that due to their shapes, nano-wires are more
likely to cross paracellularly, while nano-spheres and nano-rods used intracellular
passage to cross the intestinal epithelium. Despite previous evidence that relate the
capability of TiO2NPs to produce ROS, we have not detected oxidatively DNA damage.
However, and in accordance with the confocal images showing a great amount of NPscell
nucleus events, we detected a slight but significant general DNA damage in the
barrier’s cells.
Finally, the third study was performed under the framework of an international
mention carried out in the Biomedical Engineering Department at the Binghamton
University (Binghamton, NY, USA). Nutrient absorption is one of the main and most
important functions of the small intestine. Thus, to understand and evaluate
whether ENPs can trigger physiological potential pathologies, the activity of the
intestinal alkaline phosphatase (IAP), aminopeptidase-N (APN) and Na+/K+ ATPase
enzymes were measured after exposing the Caco-2/HT29-MTX barrier to TiO2NPs and
SiO2NPs for 4 h. Moreover, and in order to further mimic the physiological conditions
of a real digestion, the Caco-2/HT29-MTX barrier was exposed to both NPs previously
digested and co-cultured with both Escherichia coli and Lactobacillus rhamnosus, as
examples of commensal microbiota.
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Moore, Joe Dallas. "Probing Nano-Specific Interactions Between Bacteria and Antimicrobial Nanoparticles Using Microbial Community Changes and Gene Expression." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1069.
Full textAbstract:
Antimicrobial engineered nanomaterials (ENM) are increasingly incorporated into products despite limited understanding of the interactions between ENMs and bacteria that lead to toxic impacts. The hazard posed by increasing environmental release of antimicrobial ENMs is also poorly characterized. The overall objective of this thesis is to inform questions about the types of interactions that lead to an ENM inducing bacterial toxicity. Many antimicrobial ENMs are soluble, and the ion plays an important role in their toxicity. Some believe that, beyond release of ions, ENM toxicity is expected to derive from a nanoparticle (NP)-specific effect. This research compares bacterial responses to ENMs, their metal salts, and/or their transformed species within different experimental settings to improve our understanding of the interactions that enable ENM bacterial toxicity. The first objective is to characterize the potential hazard posed by pristine and transformed antimicrobial ENMs on microbial communities within a complex environmental system. One pair of ENMs (Ag0 and Ag2S) led to differential short-term impacts on surficial sediment microbial communities, while the other did not (CuO and CuS), showing that ENM transformation does not universally lead to distinct impacts. The metal ion (Cu2+) had a more profound microbial community impact than did any of the four ENMs. By 300 days the microbial community structure and composition re-converged, suggesting minimal long-term impacts of high pulse inputs of antimicrobial ENMs on microbial communities within complex environments. The second objective is to identify NP-specific effects of a common antimicrobial ENM on a model bacterium. Analysis of transcriptional responses identified NP-specific induction of a membrane stress responsive gene, providing evidence of a NP-specific effect. Otherwise, our results suggest that CuO NP toxicity triggers the same stress responses as does Cu2+, but at more moderate levels. Two ion treatments with the same total Cu input – one with pulse addition and one with gradual addition that was meant to better represent the slow dissolution of the CuO NP – led to temporally distinct responses. This calls for the use of more representative ion controls for comparison against soluble NP impacts in future nanotoxicity studies. The third objective is to investigate the potential use of CuO ENMs to reduce virulence and growth of an emerging bacterial pathogen. CuO NP exposure led to reduction in relative expression of three Staphylococcus aureus virulence factor genes, especially in methicillinresistant S. aureus (MRSA) clinical isolates. Growth was inhibited at high CuO NP concentrations for all four isolates, too. Comparison across all genes assayed showed isolatespecific transcriptional responses, but with NP- and ion-induced responses showing clear differences for each isolate, too. Altogether, this research contributes novel knowledge that will guide efforts to characterize potential hazard from release of ENMs into the environment and to apply ENMs for effective antibacterial treatment.
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Hristozov, Danail <1983>. "Development of an integrated framework for human health risk assessment of engineered nano-objects and their aggregates and agglomerates." Doctoral thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/3036.
Full textAbstract:
La produzione e l'utilizzo di nano-oggetti e dei loro aggregati e agglomerati (NOAA) sono oggetto del regolamento europeo REACH № 1907/2006, che impone l’analisi dei rischi (AR) per ogni sostanza chimica prodotta o importate in quantità superiori a 10 tonnellate all'anno. L'analisi della fattibilità dell’AR per NOAA ha identificato limiti sostanziali, quali deficit di dati e carenze metodologiche relative alle loro caratteristiche fisico-chimiche e tossicologiche, e ai percorsi di esposizione e destino finale. Queste problematiche hanno portato ad un aumento dei finanziamenti di progetti finalizzati a rendere possibile l'analisi dei rischi dei nanomateriali. Uno dei progetti finanziati dalla Commissione Europea nell’ambito del settimo programma quadro è il progetto ENPRA, che ha finanziato questo lavoro di dottorato.
Prima di ENPRA, la maggioranza delle attività scientifiche si è concentrata sulla produzione di dati sperimentali utili per l'AR. Questo approccio, tuttavia, richiede decenni per colmare le attuali lacune di conoscenza, mentre le analisi di rischio sono urgentemente necessarie oggi per attivare e supportare la richiesta normativa. Il deficit di dati quantitativi ha portato a stime del rischio largamente qualitative e in gran parte basate su giudizi esperti, tali da non giustificare sufficientemente iniziative di gestione del rischio. C'è bisogno di approcci quantitativi, capaci di integrare i dati attualmente disponibili per consentire analisi e controllo del rischio in una prospettiva di breve termine.
In risposta a questa necessità, il lavoro di tesi qui riportato propone un approccio quantitativo basato sul peso delle evidenze (Weight of Evidence, WoE) basato su metodi di analisi decisionale multicriteriale per l'integrazione di dati fisico-chimici, tossicologici e di esposizione, e supportato da giudizio esperto per consentire una robusta analisi di rischio a breve termine. Per la prima volta, un approccio WoE incorpora una valutazione esplicita della qualità dei dati, e al tempo stesso utilizza metodi consoplidati, come il margine di esposizione (Margino of exposure) e la derivazione di livelli di non-effetto.
L’approccio proposto è stato applicato a dati di esposizione e di effetto ottenuti nell’ambito di ENPRA e a dati di letteratura peer-reviewed facenti riferimento a un gruppo di NOAA commercializzati (ad esempio, biossido di titanio, ossido di zinco, nano-argento, nanotubi di carbonio a pareti multiple) al fine di classificarli e prioritizzarli per ulteriori test (ai livelli di approfondimento più bassi) e di stimare quantitativamente i rischi occupazionali (ai livelli di approfondimento più alti). Tutte le incertezze relative ai dati di input, l'uso di modelli e l'applicazione di procedure di aggregazione basati sul WoE sono stati analizzati probabilisticamente utilizzando il metodo di Monte Carlo.<br>The production and use of nano-objects and their aggregates and agglomerates (NOAA) are addressed by the European REACH regulation № 1907/2006, which requires Risk assessment (RA) for each chemical substance produced or imported in quantities above 10 tons per year. The analysis of the feasibility of the RA for NOAA has identified substantial limitations, such as data deficits and methodological concerns with respect to their physico-chemical identity, toxicity, exposure pathways and fate. These issues have led to an increased global funding of projects aimed to facilitate nano risk analysis. One of these projects is the European Seventh Framework ENPRA, which funded this doctoral work.
Before ENPRA most scientific activities were focused on the production of experimental data for RA. However, filling the knowledge gaps will take decades, while risk analyses are urgently needed to trigger adequate regulatory response. The deficit of quantitative data has led to uncertain and ambiguous, largely qualitative risk estimations based on expert judgments, which have failed to inform proper Risk management actions. There is need for quantitative approaches, which effectively combine the currently available data to allow risk analysis and control in the foreseeable future.
In response to the above need, this thesis reports a tiered quantitative Weight of evidence (WoE) framework that utilizes Multi-criteria decision analysis methods for integrating physico-chemical, toxicological and exposure data with expert judgement to allow robust near-term risk analysis. For the first time, a WoE approach incorporates an explicit evaluation of data quality, while at the same time uses well-established methods such as the Margin of exposure and the Derived No-effect Level.
The framework was applied with exposure and effects data from the ENPRA project and the peer-reviewed literature that refer to a panel of commercially available NOAA (i.e. titanium dioxide, zinc oxide, silver and multi-walled carbon nanotubes) to rank and prioritise them for further testing (in lower tiers) and quantitatively estimate their occupational risks (in a higher tier). All uncertainties related to the input data, use of models and the application of the WoE aggregation procedures were probabilistically analysed using the Monte Carlo approach.
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Adam, Véronique. "Ecotoxicological impact and risk assessment of engineered TiO2 nanomaterials on water, sediments and soil by building a combined RALCA (Risk Assessment – Life Cycle Assessment) model." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAH020/document.
Full textAbstract:
L’analyse du cycle de vie et l’évaluation du risque ont été combinées afin d’évaluer les impacts et risques potentiels de NMs de TiO2 dans l’eau, les sols et les sédiments à une échelle site-spécifique. Une approche analytique a permis de caractériser les NMs industriels dans les eaux, sols et sédiments et de déterminer leur comportement dans l’eau. Un modèle bayésien a été réalisé pour évaluer leur devenir dans les eaux et sédiments de la rivière, ainsi que leurs effets et risques associés en mésocosmes. Il a ainsi été montré que le TiO2 est présent en faible concentration dans l’eau de rivière. En mésocosmes, des risques ont été quantifiés sur deux espèces : Dreissena polymorpha et Gammarus roeseli. Il est apparu nécessaire de mieux caractériser la dimension fractale des agrégats de NMs pour comprendre leur sédimentation et de quantifier les effets des nano-TiO2 dans le milieu naturel, en dépassant l’approche par mésocosmes<br>In this work, life cycle and risk assessments were combined in order to assess the potential impacts and risks of TiO2 NMs in water, soils and sediments at a site-specific scale. Two approaches were used: (1) An analytical approach allowed the analysis of waters, sediments and soils, the characterization of industrial NMs and the determination of their aggregation behavior in water; (2) A Bayesian modeling approach was used to assess their fate in the river water and sediments, as well as their potential effects and risks in mesocosms. It was thus shown that TiO2 occurs at low concentrations in the river water. Quantifying the TiO2 mass which deposits on the sediment requires characterizing more precisely their fractal dimension. Finally, nano-TiO2 were shown to induce risks to two species in mesocosms: it is consequently necessary to assess the potential effects of the nano-TiO2 produced on the study area in mesocosms, simulating realistic conditions
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Zhang, Wen. "Characterizing, imaging, and quantifying the environmental behavior and biological interactions of metal-based nanoparticles." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/44822.
Full textAbstract:
Due to the rapid expansion of nanotechnology and the increasing applications of nanomaterials under production and development, it is essential evaluate the potential impacts on human health, ecosystems and the environment. This study is specifically focused on the interactions between metal-based nanoparticles (NPs) and target cells, aiming at exploration of the fundamental knowledge essentially useful for understanding nanotoxicity and its connections with particle properties. The whole structure of this study can be divided into three levels: the first level is to quantitatively understand physicochemical properties of NPs of interest and their dynamic changes under varying environmental conditions. The second level is to evaluate the biological interactions of representative NPs with a specific focus on the size-dependent adsorption processes, interfacial forces, cellular disruption, and membrane damages. The third level is to develop effective, accurate, and valid tools based on atomic force microscopy (AFM) to characterize NPs in terms of the nanoscale hydrophobicity and the nanoscale electric properties, which are most relevant and important properties in the bio-nano interactions. Overall, this study systematically investigated the kinetic environmental behaviors, biological interactions, and unique nano-properties of metal-based NPs, which should be of interest to people in application and implication of nanotechnology.
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Hancock, Matthew Logan. "THE FABRICATION AND CHARACTERIZATION OF METAL OXIDE NANOPARTICLES EMPLOYED IN ENVIRONMENTAL TOXICITY AND POLYMERIC NANOCOMPOSITE APPLICATIONS." UKnowledge, 2019. https://uknowledge.uky.edu/cme_etds/112.
Full textAbstract:
Ceria (cerium oxide) nanomaterials, or nanoceria, have commercial catalysis and energy storage applications. The cerium atoms on the surface of nanoceria can store or release oxygen, cycling between Ce3+ and Ce4+, and can therefore act as a therapeutic to relieve oxidative stress within living systems. Nanoceria dissolution is present in acidic environments in vivo. In order to accurately define the fate of nanoceria in vivo, nanoceria dissolution or stabilization is observed in vitro using acidic aqueous environments.
Nanoceria stabilization is a known problem even during its synthesis; in fact, a carboxylic acid, citric acid, is used in many synthesis protocols. Citric acid adsorbs onto nanoceria surfaces, capping particle formation and creating stable dispersions with extended shelf lives. Nanoceria was shown to agglomerate in the presence of some carboxylic acids over a time scale of up to 30 weeks, and degraded in others, at pH 4.5 (representing that of phagolysosomes). Sixteen carboxylic acids were tested: citric, glutaric, tricarballylic, α-hydroxybutyric, β-hydroxybutyric, adipic, malic, acetic, pimelic, succinic, lactic, tartronic, isocitric, tartaric, dihydroxymalonic, and glyceric acid. Each acid was introduced as 0.11 M, into pH 4.5 iso-osmotic solutions. Controls such as ammonium nitrate, sodium nitrate, and water were also tested to assess their effects on nanoceria dissolution and stabilization.
To further test stability, nanoceria suspensions were subject to light and dark milieu, simulating plant environments and biological systems, respectively. Light induced nanoceria agglomeration in some, but not all ligands, and is likely to be a result of UV irradiation. Light initiates free radicals generated from the ceria nanoparticles. Some of the ligands completely dissolved the nanoceria when exposed to light. Citric and malic acids form coordination complexes with cerium on the surface of the ceria nanoparticle that can inhibit agglomeration. This approach identifies key functional groups required to prevent nanoceria agglomeration. The impact of each ligand on nanoceria was analyzed and will ultimately describe the fate of nanoceria in vivo.
In addition, simulated biological fluid (SBF) exposure can change nanoceria’s surface properties and biological activity. The citrate-coated nanoceria physicochemical properties such as size, morphology, crystallinity, surface elemental composition, and charge were determined before and after exposure to simulated lung, gastric, and intestinal fluids. SBF exposure resulted in either loss or overcoating of nanoceria’s surface citrate by some of the SBF components, greater nanoceria agglomeration, and small changes in the zeta potential.
Nanocomposites are comprised of a polymer matrix embedded with nanoparticles. These nanoparticles can alter material and optical properties of the polymer. SR-399 (dipentaerythritol pentaacrylate) is a fast cure, low skin irritant monomer that contains five carbon-carbon double bonds (C=C). It is a hard, flexible polymer, and also resistant to abrasion. It can be used as a sealant, binder, coating, and as a paint additive. In this case, metal oxide nanoparticles were added to the monomer prior to polymerization. Titania nanoparticles are known to absorb UV light due to their photocatalytic nature. Titania nanoparticles were chosen due to their high stability, non-toxicity, and are relatively quick, easy, and inexpensive to manufacture. Channels in thin monomer films were created using a ferrofluid manipulated by magnetic fields.
The mechanical properties of a microfluidic device by rapid photopolymerization is dependent on the crosslinking gradient observed throughout the depth of the film. Quantitative information regarding the degree of polymerization of thin film polymers polymerized by free radical polymerization through the application of UV light is crucial to estimate material properties. In general, less cure leads to more flexibility, and more cure leads to brittleness. The objective was to quantify the degree of polymerization to approximate the C=C concentration and directly relate it to the mechanical properties of the polymer. Polymerization of C=C groups was conducted using a photoinitiator and an UV light source from one surface of a thin film of a multifunctional monomer. The C=C fraction in the film was found to vary with film depth and UV light intensity. The extents of conversion and crosslinking estimates were compared to local mechanical moduli and optical properties. A mathematical model linking the mechanical properties to the degree of polymerization, C=C composition, as a function of film depth and light intensity was then developed. For a given amount of light energy, one can predict the hardness and modulus of elasticity. The correlation between the photopolymerization and the mechanical properties can be used to optimize the mechanical properties of thin films within the manufacturing and energy constraints, and should be scalable to other multifunctional monomer systems.
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Tsang, Michael. "Cycle de vie de systèmes photovoltaïques organiques 3ème génération : élaboration d'un cadre pour étudier les avantages et les risques des technologies émergentes." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0331/document.
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Les systèmes photovoltaïques organiques sont des technologies émergentes présentant de forts potentiels d’économie de ressources et de réduction des impacts sur l'environnement et la santé humaine par rapport aux dispositifs photovoltaïques conventionnels. La méthode de l’analyse du cycle de vie est appliquée afin d'évaluer la façon dont les différents procédés de fabrication, les caractéristiques des dispositifs, la phase d’utilisation et les scénarios de fin de vie des cellules photovoltaïques organiques influent sur ces avantages potentiels. Les impacts de cette technologie émergente sont comparés aux technologies conventionnelles à base de silicium pour établir un référentiel de performance des technologies photovoltaïques.En outre, les effets potentiels sur la santé humaine de l'utilisation de nanomatériaux dans les cellules photovoltaïques organiques ont été spécifiquement étudiés ; et la pertinence de l’analyse du cycle de vie pour évaluer cette catégorie d’impact a été examinée. Ainsi, un nouveau modèle d'évaluation de l'impact sur le cycle de vie est présenté afin de quantifier les dangers potentiels posés par les nanomatériaux. Enfin,ces impacts potentiels sont comparés aux avantages des cellules photovoltaïques organiques sur les cellules à base de silicium<br>Organic photovoltaics present an emerging technology with significant potential for increasing the resource efficiencies and reducing the environmental and human health hazards of photovoltaic devices. The discipline of life-cycle assessment is applied to assess how various prospective manufacturing routes, device characteristics, uses and disposal options of organic photovoltaics influences these potential advantages. The results of this assessment are further compared to silicon based photovoltaics as a benchmark for performance. A deeper look is given to the potential human health impacts of the use of engineered nanomaterials in organic photovoltaics and the appropriateness of life-cycle assessment to evaluate this impact criteria. A newly developed life-cycle impact assessment model is presented to demonstrate whether the use of and potential hazards posed by engineered nanomaterials outweighs any of the resource efficiencies and advantages organic photovoltaics possess over silicon photovoltaics
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"Fate of Engineered Nanomaterials in Wastewater Treatment Plants." Doctoral diss., 2011. http://hdl.handle.net/2286/R.I.14427.
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abstract: As the use of engineered nanomaterials (ENMs) in consumer products becomes more common, the amount of ENMs entering wastewater treatment plants (WWTPs) increases. Investigating the fate of ENMs in WWTPs is critical for risk assessment and pollution control. The objectives of this dissertation were to (1) quantify and characterize titanium (Ti) in full-scale wastewater treatment plants, (2) quantify sorption of different ENMs to wastewater biomass in laboratory-scale batch reactors, (3) evaluate the use of a standard, soluble-pollutant sorption test method for quantifying ENM interaction with wastewater biomass, and (4) develop a mechanistic model of a biological wastewater treatment reactor to serve as the basis for modeling nanomaterial fate in WWTPs. Using titanium (Ti) as a model material for the fate of ENMs in WWTPs, Ti concentrations were measured in 10 municipal WWTPs. Ti concentrations in pant influent ranged from 181 to 3000 µg/L, and more than 96% of Ti was removed, with effluent Ti concentrations being less than 25 µg/L. Ti removed from wastewater accumulated in solids at concentrations ranging from 1 to 6 µg Ti/mg solids. Using transmission electron microscopy, spherical titanium oxide nanoparticles with diameters ranging from 4 to 30 nm were found in WWTP effluents, evidence that some nanoscale particles will pass through WWTPs and enter aquatic systems. Batch experiments were conducted to quantify sorption of different ENM types to activated sludge. Percentages of sorption to 400 mg TSS/L biomass ranged from about 10 to 90%, depending on the ENM material and functionalization. Natural organic matter, surfactants, and proteins had a stabilizing effect on most of the ENMs tested. The United States Environmental Protection Agency's standard sorption testing method (OPPTS 835.1110) used for soluble compounds was found to be inapplicable to ENMs, as freeze-dried activated sludge transforms ENMs into stable particles in suspension. In conjunction with experiments, we created a mechanistic model of the microbiological processes in membrane bioreactors to predict MBR, extended and modified this model to predict the fate of soluble micropollutants, and then discussed how the micropollutant fate model could be used to predict the fate of nanomaterials in wastewater treatment plants.<br>Dissertation/Thesis<br>Ph.D. Civil and Environmental Engineering 2011
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Wu, Ping, and 吳平. "The Carcinogenicity and Reproductive Toxicity of Engineered Nanomaterials." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/34396689092069909807.
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博士<br>國立陽明大學<br>藥理學研究所<br>102<br>Nanomaterials have been widely applied on numerous product manufactures and biomedical applications. Researcher mentioned the genotoxicity of nanomaterials and raise a big the concern on carcinogenesis. The relative evidence of inducing carcinogenesis on human cell is rare. We aim to clarify the possible mechanism of carcinogenicity of nanoparticles (NPs). In this study, we tested the commercialized NPs, multiple-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs), titanium dioxide (TiO2), to develop the high through-put imaging analysis system on testing genotoxicity-cytokinesis block micronuclei assay (CBMN). The numbers of micronucleus formation significantly increased in MWCNTs-treated cells showing the genotoxicity of MWCNTs. We would like to verify whether the genotoxicity potential of MWCNTs would lead to carcinogenicity. We further demonstrated that chronic exposure of in normal human bronchial epithelial cells (BEAS2B); can increase anchorage independent colony formation ability, which as the parameter of pre-malignant transformation. More, the incidences of tumor formation of these long term MWCNTs-treated clones were significant in xenograph model. Interestingly, this MWCNTs-induced oncogenic transformation is irreversible. It may imply that MWCNTs may affect genetic modification. Genome-wide view of chromosome aberration via the Array Comparative Genomic Hybridization analysis (aCGH) is the high resolution molecular cytogenetic technique that allows detection of chromosomal aneuploidy and structural rearrangements occurring in pre-malignant lesions. Here, we discovered that the major region of MWCNTs-induced chromosome aberration with highly amplification is chromosome 2q 31-32, whereas, several potential oncogenic genes located, including the HOXD family. These genes were further validated both on mRNA expression level and gene copy numbers. Here, we identified that HOXD9 and HOXD13 are elevated in gene copy number and mRNA expression level. Overexpression of HOXD9 or HOXD13 can transform cells into carcinogenic. Silencing of HOXD genes in MWCNTs selected clones may reverse the tumorigenicity. By signaling pathway prediction, we conclude that known oncogene, c-MYC and CCND1, may be as the downstream effector of HOXD genes signaling. In the other hand, due to the rising toxic researches on NPs and reproduction system, we would like to explore the toxicity mechanism of TiO2 in mammalian spermatozoa of mice. The effect was studied using flow cytometry, computer assistant sperm motility analysis, and in vitro fertilization assay to evaluate the sperm function exposed to nano-TiO2. Exposure of nano-TiO2 to spermatozoa, may cause sperm cell death in does dependent manner (0.01~500 μg/mL), but the effect was ROS independent. Exposure of sub-lethal dosage (1 μg/mL) of nano-TiO2 significantly (p < 0.05) decreases sperm motility. Capacitation related protein tyrosine phosphorylation of spermatozoa is also down regulated by high dosage exposure (20~100 μg/mL). In vitro fertilization assay showed that the two-cell ratio was dose dependently decreased as spermatozoa exposure to nano-TiO2. We identified the candidate protein, AldoA. TiO2 could slightly decrease tyrosine phosphorylation of AldoA, and interfered sperm function via TiO2 exposure. In vivo testis injection test, we injected TiO2 into testis of mice to monitor whether TiO2 could affect reproductive system. The result showed that Tio2 didn’t affect the size of testis. However, the production of spermatozoa is decreased. We discovered that the structure of seminiferous tubules was damaged, and TiO2 may accumulate around Leydig cell, which is important to maintain the maturation of spermatogenesis. However, we only observed decrease level of serum testosterone in high dosage treatment. We discovered that TiO2 could decrease tyrosine phosphorylation of AldoA, and interfere sperm function via TiO2 exposure. In this study, we established the toxicity assay to explore the possible toxicity of TiO2 to spermatozoa and Aldoa might partly explain the mechanism in TiO2 induced sperm toxicity. In the thesis, we emphasized that the application of NPs is critical and it is crucial to monitor human health while exposing to nanomaterials.
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Romoser, Amelia Antonia. "Cytotoxicological Response to Engineered Nanomaterials: A Pathway-Driven Process." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10877.
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Nanoparticles, while included in a growing number of consumer products, may pose risks to human health due to heavy metal leaching and/or the production of reactive oxygen species following exposures. Subcellular mechanisms of action triggered as a result of exposure to various nanoparticles are still largely unexplored. In this work, an effort to elucidate such toxicological parameters was accomplished by evaluating oxidative stress generation, changes in gene and protein expression, and cell cycle status after low-dose exposures to a variety of metal and carbon-based nanomaterials in primary human dermal cells. Additionally, mitigation of nanoparticle toxicity via microencapsulation was investigated to assess the feasibility of utilizing nanomaterials in dermally implantable biosensor applications.
Cellular immune and inflammatory processes were measured via qPCR and immunoblotting, which revealed gene and protein expression modulation along the NF-kappaB pathway after a variety of nanoparticle exposures. The role of immunoregulatory transcription factor NF-kappaB was examined in an oxidative stress context in cells exposed to a panel of nanoparticles, whereby glutathione conversion and modulation of oxidative stress proteins in normal and NF-kappaB knockdown human dermal fibroblasts were monitored. Results revealed decreased antioxidant response and corresponding increased levels of oxidative stress and cell death in exposed normal cells, compared to NF-kappaB incompetent cells. However, reactive oxygen species production was not an absolute precursor to DNA damage, which was measured by the comet assay, gamma-H2AX expression, and flow cytometry. Protein analysis revealed that map kinase p38, rather than p53, was involved in the halting of the cell cycle in S-phase after ZnO exposures, which caused DNA double strand breaks.
Microencapsulation of fluorescent quantum dot nanoparticles, specifically, was utilized as a method to improve system functionality and surrounding cellular viability for the purpose of a dermal analyte detection assay. In vitro results indicated a functional localization of nanoparticles, as well as cessation of cellular uptake. Subsequently, cellular metabolism was unaffected over the range of time and concentrations tested in comparison to unencapsulated quantum dot treatments, indicating the usefulness of this technique in developing nanoparticle-driven biomedical applications.
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Arefe, Ghidewon. "Engineered Two-Dimensional Nanomaterials for Advanced Opto-electronic Applications." Thesis, 2018. https://doi.org/10.7916/D83R29RW.
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Two dimensional (2D) materials have unique properties that make them exciting candidates for various optical and electronic applications. Materials such as graphene and transition metal dichalcogenides (TMDCs) have been intensively studied recently with researchers racing to show advances in 2D device performance while developing a better understanding of the material properties. Despite recent advances,there are still significant roadblocks facing the use of 2D materials for real-world applications. The ability to make reliable, low-resistance electrical contact to TMDCs such as molybdeum disulfide (MoS22) has been a challenge that many researchers have sought to overcome with novel solutions. The work laid out in this dissertation uses novel techniques for addressing these issues through the use of improved device fabrication and with a clean, and potentially scalable doping method to tune 2D material properties.A high-performance field-effect transistor (FET) was fabricated using a new device platform that combined graphene leads with dielectric encapsulation leading to the highest reported value for electron mobility in MoS2. Device fabrication techniques were also investigated and a new, commercially available lithography tool (NanoFrazor) was used to pattern contacts directly onto monolayer MoS2. Through a series of control experiments with conventional lithography, a clear improvement in contact resistance was observed with the use of the NanoFrazor. Plasma-doping, a dry and clean process, was investigated as an alternative to traditional wet-chemistry doping techniques. In addition to developing doping parameters with a chlorine plasma treatment of graphene, a series of experiments on doped graphene were conducted to study its effect on optical properties. Whereas previous studies used electrostatic gating to modify graphene’s optical properties, this work with plasma-doped graphene showed the ability to tune absorbence and plasmon wavelength without the need for an applied bias opening the door to the potential for low-power applications. This work is a just small contribution to the larger body of research in this field but hopefully represents a meaningful step towards a greater understanding of 2D materials and the realization of functional applications.
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Gustafsson, Åsa. "Nanomaterials : respiratory and immunological effects following inhalation of engineered nanoparticles." Doctoral thesis, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-95724.
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Background Nanotechnology is an important and promising field that can lead to improved environment and human health and contribute to a better social and economic development. Materials in nanoscale have unique physiochemical properties which allow for completely new technical applications. Enlarged surface area and properties due to quantum physics are among the properties that distinguish the nanoscale. Nano safety has evolved as a discipline to evaluate the adverse health effects from engineered nanomaterials (ENMs). The prevalence of allergic diseases is increasing in the society. An additional issue is the influence of inherited factors on the health responses to ENMs. The aim of this thesis was to investigate the respiratory, inflammatory, and immunological effects following inhalation of ENMs; both sensitive and genetically susceptible individuals were used. Sensitive individuals refer to individuals with pre-existing respiratory diseases, such as allergic asthma, and genetically susceptible individuals refer to individuals prone to autoimmune and allergic diseases. Methods In vivo models of mice and rats were used. In study I the inflammatory and immune responses following exposure to titanium dioxide nanoparticles (TiO2 NPs) were investigated. The effect of when the TiO2 NP exposure occurs during the development of allergic airway inflammation was investigated in study II, with regards to respiratory, inflammatory, and immune responses. In study III, the influence of the genetics on the respiratory, inflammatory, and immune responses, following TiO2 NP exposure to naïve and sensitive rats was evaluated. In study IV, the inflammatory and immune responses of naïve mice and mice with an allergic airway inflammation were studied in lung fluid and lymph nodes draining the airways following inhalation to hematite NPs (α-Fe2O2). Results Exposure to TiO2 NPs induced a long-lasting lymphocytic response in the airways, indicating a persistent immune stimulation. The dose and timing of TiO2 NP exposure affected the airway response in mice with allergic airway disease. When the mice were exposed to particles and an allergen during the same period, a decline in general health was observed. By comparing different inbred rat strains it was demonstrated that genetically determined factors influence the immune and respiratory responses to TiO2 NP exposure in both naïve and sensitive individuals. Exposure to hematite NPs resulted in different cellular responses: naïve mice had increased numbers of cells while mice with allergic airway inflammation had decreased cell numbers in BALF. Analogous cell responses were also observed in the lung draining lymph nodes. Conclusion Altogether, this thesis emphasises the complexity of assessing health risks associated with nanoparticle exposure and the importance of including sensitive populations when evaluating adverse health effects of ENMs.<br><p>Forskningsfinansiär: Umeå Center for Environmental Research, and by the Swedish Ministry of Defence</p>