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Microstructural analysis of carbon nanomaterials produced from pyrolysis/combustion of Styrene-Butadiene-Rubber (SBR)

ALVES, Joner Oliveira; ZHUO, Chuanwei; LEVENDIS, Yiannis Angelo; TENÓRIO, Jorge Alberto Soares
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.974734%
Styrene-Butadiene-Rubber (SBR) is a synthetic rubber copolymer used to fabricate several products. This study aims to demonstrate the use of SBR as feedstock for carbon nanomaterials (nanofibers and nanotubes) growth, and therefore to establish a novel process for destination of waste products containing SBR. A three stage electrically heated flow reactor was used. Small pellets of rubber were pyrolyzed at a temperature of 1000 ºC. The pyrolyzates were mixed with oxygen-containing gases and were burned. The products of combustion were used to synthesize the carbon nanomaterials (CNMs) at the presence of a catalyst. CNMs have a wide range of potential applications due to their extraordinary mechanical, thermal and electrical properties. Produced materials were characterized by SEM and TEM, whereas combustion products were assessed using GC. Results showed that CNMs with outer diameters of 30-100 nm and lengths of about 30 µm were formed. Therefore, it was demonstrated that waste products containing SBR can be used to generate CNMs which are value-added products of intense technological interest.; CNPQ; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)

Catalytic conversion of wastes from the bioethanol production into carbon nanomaterials

ALVES, Joner O.; ZHUO, Chuanwei; LEVENDIS, Yiannis A.; TENORIO, Jorge A. S.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
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This work addressed the production of carbon nanomaterials (CNMs) by catalytic conversion of wastes from the bioethanol industry, in the form of either sugarcane bagasse or corn-derived distillers dried grains with solubles (DDGS). Both bagasse and DDGS were pyrolysed at temperatures in the range of 600-1000 degrees C. The pyrolyzate gases were then used as CNM growth agents by chemical vapor deposition on stainless steel meshes, serving as both catalysts and substrates. CNM synthesis temperatures of 750-1000 degrees C were explored, and it was determined that their growth was most pronounced at 1000 degrees C. The nanomaterials produced from pyrolysis of bagasse were in the form of long, straight, multi-wall nanotubes with smooth walls and axially uniform diameters. Typical lengths were circa 50 mu m and diameters were in the range of 20-80 nm. The nanomaterials produced from pyrolysis of DDGS were in the form of long, entangled, rope-like structures with rugged walls, and axially non-uniform diameters. Typical diameters were in the range of 100-300 nm and their lengths were in the tens of microns. This process also produces a bio-syngas byproduct that is enriched in hydrogen. (C) 2011 Elsevier B.V. All rights reserved.; CNPQ-Brazil; CAPES[04/CII-2008 - Rede Nanobiotec-Brasil]

Estudo da interação de nanomateriais com modelos de membranas celulares e com células-tronco neurais; Interaction of nanomaterials with cell membrane models and with stem cells

Uehara, Thiers Massami
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/09/2014 PT
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O desenvolvimento da nanociência e nanotecnologia promoveu uma nova fronteira no estudo da matéria, permitindo que materiais já conhecidos tivessem suas propriedades redescobertas ao serem manipulados em nível molecular. Vários materiais vêm apresentando relevância na nanociência e nanotecnologia, como os nanotubos de carbono (CNTs), nanopartículas (NPs) e óxido de grafeno, uma vez que os CNTs e óxido de grafeno são dotados de propriedades mecânicas, térmicas e elétricas que os tornam apropriados para o desenvolvimento e a aplicação em dispositivos, especialmente na área biotecnológica e de sensores. Diversas áreas se beneficiam com o uso da tecnologia em nanopartículas (NPs), por exemplo: alimentícia, médica, agronegócio, cosmética, etc. Uma possível perspectiva na utilização desses nanomateriais em sistemas biológicos torna muito interessante investigar como tais materiais interagem em nível molecular com modelos de membranas celulares e com células. Esta tese tem como objetivos: i) investigar detalhadamente a interação entre nanopartículas (Fe3O4/Dextran; Fe3O4/PDAC; PDAC; Dextran) e nanotubos de carbono com modelos de membranas celulares; e ii) desenvolver nanofibras poliméricas pela técnica de electrospinning para ser utilizada com óxido de grafeno como modelos mimetizados (scaffolds) para a diferenciação de células-tronco neurais. Os filmes ultrafinos foram fabricados utilizando as técnicas de Langmuir e Langmuir-Blodgett. Esses nanomateriais foram avaliados através da técnica de Espectroscopia vibracional por Geração de Soma de Frequências. A espectroscopia SFG é sensível a interfaces. Nanofibras de Poli(ε-Caprolactone) foram fabricadas pela técnica de electrospinning. Scaffolds com óxido de grafeno/Nanofibras de Poli(ε-Caprolactone) foram desenvolvidos como suportes sólidos para a diferenciação de células-tronco neurais de rato. Óxido de grafeno em diferentes concentrações foi incorporado nas nanofibras poliméricas. Os modelos deste sistema foram investigados por imagens de Microscopia Eletrônica de Varredura. Os resultados mostraram que a carga eletrostática de cada fosfolipídio utilizado pode influenciar nas interações com os nanomateriais (nanopartículas ou nanotubos de carbono)...

Nanomateriais luminomagnéticos visando aplicações biológicas: síntese, propriedades, funcionalização e estabilidade coloidal; LUMINOMAGNETIC NANOMATERIALS FOR BIOLOGICAL APPLICATIONS: SYNTHESIS, PROPERTIES, FUNCTIONALIZATION AND COLLOIDAL STABILITY

Souza, Caio Guilherme Secco de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 10/04/2015 PT
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Neste trabalho, foi realizado um estudo da obtenção de nanomateriais luminomagnéticos visando potenciais aplicações biológicas, a partir de dois diferentes tipos de estruturas, sendo elas: a formação de heteronanoestruturas luminomagnéticas de NPM de FePt/Fe3O4-CdSe recobertas com sílica; e a formação de nanomateriais luminomagnéticos por ligação covalente entre NPM de FePt/Fe3O4-Dopa-PIMA-PEG-NH2 e pontos quânticos de CdSe/ZnS-LA-PEG-COOH. Para o primeiro tipo de nanomaterial citado, foram testadas duas metodologias para obtenção das heteronanoestruturas: a mudança da estabilidade coloidal pela adição de pequenas quantidades de NaCl no meio contendo as NPM e os pontos quânticos previamente sintetizados; e o método de injeção a quente do precursor de selênio em um meio contendo as NPM como sementes, o precursor de cádmio e os agentes de superfície. O método de injeção a quente foi o que apresentou melhores condições para a formação das heteronanoestruturas. Para providenciar estabilidade coloidal em meio aquoso e superfície com biocompatibilidade, foi realizado o recobrimento com sílica na superfície das heteronanoestruturas luminomagnéticas com melhores condições. Para essa amostra, o tamanho médio obtido foi de 25...

Short term toxicity of nanomaterials in different development stages of amphibians; Toxicidade de nanomateriais em diferentes estádios do ciclo de vida de anfíbios

Costa, Nuno Mouta Faria da
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Dissertação de Mestrado
ENG
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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...

Microstructural analysis of carbon nanomaterials produced from pyrolysis/combustion of Styrene-Butadiene-Rubber (SBR)

Alves,Joner Oliveira; Zhuo,Chuanwei; Levendis,Yiannis Angelo; Tenório,Jorge Alberto Soares
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 EN
Relevância na Pesquisa
36.974734%
Styrene-Butadiene-Rubber (SBR) is a synthetic rubber copolymer used to fabricate several products. This study aims to demonstrate the use of SBR as feedstock for carbon nanomaterials (nanofibers and nanotubes) growth, and therefore to establish a novel process for destination of waste products containing SBR. A three stage electrically heated flow reactor was used. Small pellets of rubber were pyrolyzed at a temperature of 1000 ºC. The pyrolyzates were mixed with oxygen-containing gases and were burned. The products of combustion were used to synthesize the carbon nanomaterials (CNMs) at the presence of a catalyst. CNMs have a wide range of potential applications due to their extraordinary mechanical, thermal and electrical properties. Produced materials were characterized by SEM and TEM, whereas combustion products were assessed using GC. Results showed that CNMs with outer diameters of 30-100 nm and lengths of about 30 µm were formed. Therefore, it was demonstrated that waste products containing SBR can be used to generate CNMs which are value-added products of intense technological interest.

Emerging methods and tools for environmental risk assessment, decision-making, and policy for nanomaterials: summary of NATO Advanced Research Workshop

Linkov, Igor; Steevens, Jeffery; Adlakha-Hutcheon, Gitanjali; Bennett, Erin; Chappell, Mark; Colvin, Vicki; Davis, J. Michael; Davis, Thomas; Elder, Alison; Hansen, Steffen Foss; Hakkinen, Pertti Bert; Hussain, Saber M.; Karkan, Delara; Korenstein, Rafi;
Fonte: Springer Netherlands Publicador: Springer Netherlands
Tipo: Artigo de Revista Científica
EN_US
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Nanomaterials and their associated technologies hold promising opportunities for the development of new materials and applications in a wide variety of disciplines, including medicine, environmental remediation, waste treatment, and energy conservation. However, current information regarding the environmental effects and health risks associated with nanomaterials is limited and sometimes contradictory. This article summarizes the conclusions of a 2008 NATO workshop designed to evaluate the wide-scale implications (e.g., benefits, risks, and costs) of the use of nanomaterials on human health and the environment. A unique feature of this workshop was its interdisciplinary nature and focus on the practical needs of policy decision makers. Workshop presentations and discussion panels were structured along four main themes: technology and benefits, human health risk, environmental risk, and policy implications. Four corresponding working groups (WGs) were formed to develop detailed summaries of the state-of-the-science in their respective areas and to discuss emerging gaps and research needs. The WGs identified gaps between the rapid advances in the types and applications of nanomaterials and the slower pace of human health and environmental risk science...

Optically-Active Nanomaterials for Diagnostic and Therapeutic Applications in Ovarian Cancer

Bagley, Alexander Francis
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
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The clinical management of cancer has principally relied upon surgery, radiation therapy, and chemotherapy for many decades. Despite recent advances in molecularly-targeted diagnostic and therapeutic agents, the long-term survival rates in patients with solid malignancies including ovarian cancer have improved only incrementally. Nanotechnologies designed to locally interrogate and modulate the tumor microenvironment offer a promising opportunity to enhance existing treatment modalities and establish new therapeutic paradigms. By virtue of their elemental composition, geometry, and surface chemistry, nanomaterials can be engineered with optical and pharmacokinetic properties which permit these agents to localize, fluoresce, and deposit energy within tumors. Nanomaterials therefore provide a clear route towards future approaches for sensitive diagnosis and imaging of tumors and targeted therapeutic delivery.

GaN Based Nanomaterials Fabrication with Anodic Aluminium Oxide by MOCVD

Wang, Yadong; Sander, Melissa; Peng, Chen; Chua, Soo-Jin; Fonstad, Clifton G. Jr.
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Tipo: Artigo de Revista Científica Formato: 683180 bytes; application/pdf
EN_US
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A highly self-ordered hexagonal array of cylindrical pores has been fabricated by anodizing a thin film of Al on substrate and subsequent growth of GaN and InGaN in these nanoholes has been performed. This AAO template-based synthesis method provides a low cost process to fabricate GaN-based nanomaterials fabrication.; Singapore-MIT Alliance (SMA)

Characterizing Engineered Nanomaterials: From Environmental, Health and Safety Research to the Development of Shaped Nanosphere Lithography for Metamaterials

Lewicka, Zuzanna
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
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In this thesis two issues in nanotechnology have been addressed. The first is the comprehensive characterization of engineered nanomaterials prior to their examination in toxicology and environmental studies. The second is the development of a method to produce nanostructure arrays over large areas and for low cost. A major challenge when assessing nanomaterial’s risks is the robust characterization of their physicochemical properties, particularly in commercial products. Such data allows the critical features for biological outcomes to be determined. This work focused on the inorganic oxides that were studied in powdered and dispersed forms as well as directly in consumer sunscreen products. The most important finding was that the commercial sunscreens that listed titania or zinc oxide as ingredients contained nanoscale materials. Cell free photochemical tests revealed that ZnO particles without any surface coating were more active at generating ROS than surface coated TiO2 nanoparticles. These studies make clear the importance of exposure studies that examine the native form of nanomaterials directly in commercial products. The second part of this thesis presents the development of a new method to fabricate gold nanoring and nanocrescent arrays over large areas; such materials have unique optical properties consonant with those described as metamaterials. A new shaped nanosphere lithography approach was used to manipulate the form of silica nanospheres packed onto a surface; the resulting array of mushroom structures provided a mask that after gold evaporation and etching left either golden rings or crescents over the surface. The structures had tunable features...

Ordering and motion of anisotropic nanomaterials

Khatua, Saumyakanti
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
36.833682%
Multi-scale ordering of the components is of utmost importance for the preparation of any functional system. This is particularly interesting for the assembly of plamonic nanoparticles which show drastic differences in their optical properties compared to the individual counterparts, giving rise to the unique opportunity to perform enhanced spectroscopies, sensing, and transporting optical information below the diffraction limitation of light. The control over ordering of nanoscale materials is therefore of paramount importance. Template based bottom up approaches such as using nematic liquid crystals promise a long range, reversible ordering of nanomaterials. It also promises active control over plasmonic properties of metal nanoparticles due to the electric field induced reorientation of liquid crystals, resulting in a change of the local refractive index. This thesis discusses the possibility of ordering anisotropic metal nanoparticles and performing active modulaton of the plasmonics response using a nematic liquid crystals. While long polymer chains can be solvated and aligned in liquid crystal solvents, anisotropic metal nanoparticles could not be dissolved in the nematic liquid crystal phase because of their poor solubility. Here...

Synthesis and application of phosphonate scale inhibitor nanomaterials for oilfield scale control

Zhang, Ping
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
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In this study, several synthesis routes were adopted to prepare nanometer sized metal-phosphonate particles to expand their use in the delivery of phosphonate mineral scale inhibitors into formation porous media for oilfield scale control. An aqueous solution of calcium chloride or zinc chloride was mixed with a basic phosphonate solution to form nanometer sized particles. The physical and chemical properties of the fabricated nanomaterials and their solutions have been carefully evaluated. The obtained nanomaterial suspensions were stable for a certain period of time at 70°C in saline solutions. The nanomaterials demonstrated a good migration performance through formation porous media. Transportability was affected by both the flow velocity and the surface chemistry of the nanomaterials as well as the formation medium. The transport of these nanomaterials can be enhanced, when the formation materials were pre-flushed by surfactant solutions. The potential application of the synthesized nanomaterials for scale treatment in oilfields has been investigated by a series of laboratory squeeze simulation tests. The synthesized nanomaterials were injected into formation medium and retained on the medium surfaces. After a shut-in period, the inhibitor nanomaterials slowly released phosphonates into the produced fluid to prevent scale formation. It has been observed that the prepared nanomaterials are able to return phosphonates in a similar return profile as that of the conventional acidic pills. Moreover...

Impact of Sunlight and Natural Organic Matter on the Fate, Transport, and Toxicity of Carbon Based Nanomaterials

Qu, Xiaolei
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
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The fast growing production of carbon based nanomaterials (CNMs) and their potential widespread use in consumer products raise concerns regarding their potential risks to human health and ecosystems. The present study investigated the role of photochemical transformation and natural organic matter (NOM) in the fate, transport, and toxicity of fullerenes and carbon nanotubes (CNTs) in natural aquatic systems, providing fundamental information for risk assessment and management. Photochemical transformation of aqueous fullerene nanoparticles (nC60) and CNTs occurs at significant rates under UVA irradiation at intensity similar to that in sunlight. The transformation processes are mediated by self-generated ROS, resulting in changes of surface structure depending on the initial surface oxidation state of CNMs. UVA irradiation leads to oxygenation of nC60 surface and decarboxylation of carboxylated multi-walled carbon nanotubes (COOH-MWNTs). The environmental transport of CNMs is significantly affected by their surface chemistry, concentration and species of electrolytes, and concentration and properties of co-existing NOM. In electrolyte solutions without NOM, the mobility of CNMs is largely decided by their surface chemistry, primarily the oxygen-containing functional groups. In NaCl solutions...

Nanomaterials Enabled Dye-sensitized Solar Cells

Dong, Pei
Fonte: Universidade Rice Publicador: Universidade Rice
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Dye sensitized solar cells (DSCs), as the third generation of solar cells, have attracted tremendous attention for their unique properties. The semi-transparent nature, low-cost, environmental friendliness, and convenient manufacturing conditions of this generation of solar cells are promising aspects of DSCs that make them competitive in their future applications. However, much improvement in many aspects of DSCs’ is required for the realization of its full potential. In this thesis, various nanomaterials, such as graphene, multi wall carbon nanotubes, vertically aligned single wall carbon nanotubes, hybrid structures and etc, have been used to improve the performance of DSCs. First, the application of graphene covered metal grids as transparent conductive electrodes in DSCs is explored. It is demonstrated that the mechanical properties of these flexible hybrid transparent electrodes, in both bending and stretching tests, are better than their oxide-based counter parts. Moreover, different kinds of carbon nanotubes, for instance vertically aligned single wall carbon nanotubes, have been used as a replacement for traditional platinum counter electrodes, in both iodine electrolyte, and sulfide-electrolyte. Further, a flexible, seamlessly connected...

Carbon Nanomaterials for Detection, Assessment and Purification of Oil and Natural Gas

Hwang, Chih-Chau
Fonte: Universidade Rice Publicador: Universidade Rice
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This thesis studies several carbon nanomaterials. Their synthesis and characterization are studied as well as their potential applications to the oil industry. The carbon nanomaterials studied here include mesoporous carbon (CMK-3), sulfur- or nitrogen-doped porous carbon (SPC or NPC), and commercial carbon black (CB). Through appropriate functionalization, these carbon nanomaterials exhibit unique properties and their performances in detection, assessment as well as purification of oil and natural gas are studied and demonstrated. First, it was shown that amine-modified CMK-3 composites, polyethylenimine-CMK-3 (PEI-CMK-3) and polyvinylamine-CMK-3 (PVA-CMK-3) can be synthesized through in situ polymerization of amine species within the channels of the CMK-3. The synthesis process results in the entrapped amine polymers interpenetrating the composite frameworks of the CMK-3, improving the CO2 capture performance and recycle stability. CO2 uptake by the synthesized composites was determined using a gravimetric method at 30 °C and 1 atm; the 39% PEI-CMK-3 composite had ~12 wt% (3.1 mmol/g) CO2 uptake capacity and the 37% PVA-CMK-3 composite had ~13 wt% (3.5 mmol/g) CO2 uptake capacity. A desorption temperature of 75 °C was sufficient for regeneration. The CO2 uptake was the same when using 10% CO2 in a 90% CH4...

Carbon Nanomaterials for Fibers, Photonics and Composites

Xiang, Changsheng
Fonte: Universidade Rice Publicador: Universidade Rice
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This thesis investigates various carbon nanomaterials from the basic synthesis to the characterizations and applications in fibers, photonics and composites. The carbon nanomaterials we studied include graphene, graphene oxide, graphene nanoribbons, functionalized graphene nanoribbons, graphene oxide nanoribbons, graphene quantum dots and carbon nanotubes. With all these chemical approaches, these carbon nanomaterials’ mechanical, electrical, photonic and gas barrier properties were carefully studied and demonstrated.

Stevia rebaudiana loaded titanium oxide nanomaterials as an antidiabetic agent in rats

Langle,Ariadna; González-Coronel,Marco Antonio; Carmona-Gutiérrez,Genaro; Moreno-Rodríguez,José Albino; Venegas,Berenice; Muñoz,Guadalupe; Treviño,Samuel; Díaz,Alfonso
Fonte: Sociedade Brasileira de Farmacognosia Publicador: Sociedade Brasileira de Farmacognosia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2015 EN
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Abstract Stevia rebaudiana (Bertoni) Bertoni, Asteraceae, is a plant with hypoglycemic and antihyperlipidemic properties. S. rebaudiana (SrB) has become a lead candidate for the treatment of the diabetes mellitus. However, chronic administrations of S. rebaudiana are required to cause the normoglycemic effect. Importantly, nanomaterials in general and titanium dioxide (TiO2) in particular have become effective tools for drug delivery. In this work, we obtained TiO2 nanomaterials with SrB at different concentrations (10, 20 and 30 µM) by sol–gel method. After this nanomaterials were characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. Where it was demonstrated, the presence of the S. rebaudiana in TiO2 nanomaterials, which were observed as hemispherical agglomerated particles of different sizes. The nanomaterials were evaluated in male rats whose diabetes mellitus-phenotype was induced by alloxan (200 mg/kg, i.p.). The co-administration of TiO2-SrB (20 and 30 µM) induced a significant and permanent decrease in the glucose concentration since 4 h, until 30 days post-administration. Likewise, the concentrations of insulin, glycosylated hemoglobin, cholesterol, and triacylglycerides showed a significant recovery to basal levels. The major finding of the study was that the TiO2-SrB (20 and 30 µM) has a potent and prolonged activity antidiabetic. TiO2 can be considered like an appropriated vehicle in the continuous freeing of active substances to treat of diabetes mellitus.

Nanomaterials safety investigation: analysis of genotoxic effects in a human bronchial epithelial cell line

Louro, Henriqueta; Tavares, Ana; Silva, Maria João
Fonte: Instituto Nacional de Saúde Doutor Ricardo Jorge, IP Publicador: Instituto Nacional de Saúde Doutor Ricardo Jorge, IP
Tipo: Conferência ou Objeto de Conferência
Publicado em /03/2013 ENG
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The human and environment exposure to manufactured nanomaterials (NMs) has been increasing worldwide. The specific properties of MNMs (as size and high surface area/mass) render them attractive for many applications, but may also be associated to higher toxicity in biological systems and adverse effects in humans. The objective of the present work was to evaluate the potential genotoxic effects of several well characterized NMs- titanium dioxide (TiO2), a multiwalled carbon-nanotube (MWCNT) and silicon dioxide (SiO2)- in human bronchial epithelial (BEAS-2B) cells. Dispersions of each NM were prepared according to a standardized protocol and BEAS-2B cultures were exposed to several concentrations of each NM. Genotoxicity was characterized by the combination of the comet and the cytokinesis-block micronucleus assays. Concurrent positive chemical controls (EMS and MMC) and a nanoparticle control (ZnO) were included. The results showed that the exposure of the cells to TiO2 (32-128 µg/cm2, 24h) caused a 3-fold increase in the level of DNA damage (comet assay) over control (P<0.058) but no dose-response could be ascribed using regression analysis. Moreover, this NM was not able to induce micronucleus formation in the same cell line (48h exposure). The MWCNT and SiO2 NM yielded negative results in both genotoxicity assays. Finally...

Safety evaluation of manufactured nanomaterials: comparison of genotoxic effects of multi-walled carbon nanotubes in two human cell lines

Silva, Maria João; Tavares, Ana; Antunes, Susana; Lavinha, João; Louro, Henriqueta
Fonte: Instituto Nacional de Saúde Doutor Ricardo Jorge, IP Publicador: Instituto Nacional de Saúde Doutor Ricardo Jorge, IP
Tipo: Conferência ou Objeto de Conferência
Publicado em /02/2013 ENG
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Nanotechnologies are developing very rapidly and presently, nanomaterials are increasingly used in a wide range of applications in science, industry and biomedicine. While a lot of effort has been put in the development of new manufactured nanomaterials (NMs) and in many innovative applications of nanothecnologies, comparatively less research has been performed to evaluate their safety for humans and the environment. Solid information about hazard is lacking for the vast majority of nanomaterials, especially related to chronic exposure to low doses, that are likely to occur though consumers products. The genotoxic effects of NMs, which may be linked to carcinogenic effects, are of special concern because cancer has a long latency period and thereby these effects can be less obvious and more difficult to predict than the acute effects. Multi-walled carbon nanotubes (MWCNT) are NMs that have been widely applied in structural composites, energy appliances and electronics [1]. The same physicochemical properties that have rendered them attractive for those purposes might also underlie relevant biological effects with impact on human health and on environment. Size, surface properties, agglomeration state, biopersistence and dose are likely to influence cell responses to MWCNT...

Facilitating the safety evaluation of manufactured nanomaterials by characterising their potential genotoxic hazard: final publishable report

Nanogenotox Partners
Fonte: ANSES Publicador: ANSES
Tipo: Relatório
Publicado em /03/2013 ENG
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Nanogenotox Partners (INSA): Susana Antunes, João Lavinha, Henriqueta Louro, Ana Tavares, Maria João Silva, Nadia Vital; Project Coordinator: French Agency for Food, Environmental and Occupational Health & Safety (ANSES); Nanotechnology is a highly strategic industrial and economic sector showing enormous potential benefits for many societal and environmental domains. Human exposure to manufactured nanomaterials (MNs)present in consumer products may occur during several phases of their life cycle, from synthesis, production and inclusion in the products to the release of MNs into the environment. The lack of scientific knowledge and the absence of evidence demonstrating the safety of some nanomaterials make regulation a challenge. In 2009 the Executive Agency for Health and Consumers (EAHC) awarded a grant through the second programme of Community action in the field of health (2008-2013) for a Joint Action (JA) on the “Safety of nanomaterials”. The NANOGENOTOX Joint Action started in March 2010 for a period of 3 years and had a total budget of over 6.2 million euros, 46% co-funded by the European Commission’s Health Programme. It was coordinated by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES). Sixteen associated partners from 11 member states and 13 collaborating partners came together to pool their expertise and competences.; This document arises from the NANOGENOTOX Joint Action which has received funding from the European Union...