CuNi nanoparticles were synthesized using a new polyol synthesis method. Three different CuxNi1-x catalysts were synthesized where x = 20, 50 and 80. The nanoparticles were deposited on carbon, C, gamma-alumina, γ-Al2O3, yttria-stabilized zirconia, YSZ, and samariumdoped ceria, SDC. Each set of catalysts was tested using the Reverse Water Gas Shift, RWGS, reaction under atmospheric pressure and at temperatures ranging from 400°C-700°C. The experiments were repeated 3 times to ensure stability and reproducibility. Platinum nanoparticles were also deposited on the same supports and tested for the RWGS reaction at the same conditions. The CuNi nanoparticles were characterized using a variety of different techniques. Xray diffraction, XRD, measurements demonstrate the resence of two CuNi solid solutions: one Cu rich solid solution, and the other a Ni rich solid solution. X-ray photo electron spectroscopy, XPS, measurements show Cu enrichment on all catalytic surfaces. Scanning electron microscopy, SEM, measurements show CuNi nanoparticles ranging in size from 4 nm to 100 nm. Some agglomeration was observed. SDC showed the best yield with all catalysts. Furthermore, high oxygen vacancy content was shown to increase yield of CO for the RWGS reaction. Cu50Ni50/SDC shows the combination of highest yield of CO and the best stability among CuNi catalysts. It also has similar yields (39.8%) as Pt/SDC at 700°C, which achieved the equilibrium yield at that temperature (43.9%). The catalyst was stable for 48 hours when exposed to high temperatures (600-700°C). There was no CH4 observed during any of the experiments when the partial pressure of the reactant gases was fed stoichiometrically. Partial pressure variation experiments demonstrated the presence of CH4 when the partial pressure of hydrogen was increased to twice the value of the partial pressure of CO2.

The increased demand of fossil fuel along with the depletion of economical crude oil resources, environmental challenges such as the accumulation of CO2 and other greenhouse gases in the atmosphere and the reduction of the dependence on imported oil are some of the motivations for the huge interest in biofuels. Biobutanol produced from ABE fermentation has been considered to be a good partial replacement for fossil fuels. However, challenges such as the need for inexpensive feed-stocks, improved fermentation performance to achieve higher final butanol concentration and higher yield, an efficient method for solvent recovery, and water recycle are the main obstacles to make the production of this alcohol economically viable. Pervaporation, a membrane-based process, is considered to be an attractive separation method to remove butanol from ABE fermentation broth. Among the membranes used for butanol separation, PDMS membranes showed reasonable performance such as good permeability, and appropriate selectivity for butanol separation by pervaporation. However, PDMS membranes need to be improved in terms of performance to be applicable in large scale butanol production plants. In this study, activated carbon nanoparticles have been embedded into the matrix of the PDMS membrane to improve its separation performance and, in particular, the permeation flux and butanol selectivity. Result showed that the presence of nanoparticles improves the PDMS membrane performance up to a certain particle loading. Moreover, it was shown that the operating conditions have a major impact on the pervaporation membrane separation process. The best membrane for pervaporation separation of butanol from binary aqueous solutions was obtained for a 6 wt% particle concentration where the total permeation flux and butanol selectivity increased by 42.6% and 51.9%, respectively, compared to neat PDMS membranes. Moreover, the best performance for the separation of butanol from ABE model solutions was achieved for an 8 wt% nanoparticle loading. Both the selectivity for butanol and the total permeation flux more than doubled in comparison to neat PDMS membranes prepared in this study. Moreover, in order to compare the PDMS/AC mixed matrix membrane performance for pervaporation separation of butanol from binary and ABE model solutions with PDMS membranes available on the market, experiments were also performed with a commercial PDMS membrane. Result of butanol separation from ABE model solutions showed that mixed matrix membranes with 8 wt% nanoparticles loading had a higher permeation flux than that of the commercial membranes. It was clearly shown that the presence of activated carbon nanoparticles in the matrix of the PDMS would be beneficial for the pervaporation separation of butanol from ABE fermentation broths. To better comprehend how the presence of activated carbon nanoparticles in the polymeric membranes enhance the performance of the membranes, a series of numerical simulations were performed. A finite difference model was developed to simulate the mass transfer of permeating components through mixed matrix membranes by pervaporation for a wide range of relative permeability, nanoparticle loading, particle shape, particle size and different filler adsorption isotherms. Finally, an investigation has been performed to optimize the butanol pervaporation separation process from ABE fermentation broth at an industrial scale.

Dans les installations nucléaires, les particules en suspension sont le vecteur d’une grande partie de la contamination radiologique. Pour cette raison, l'IRSN (Institut de Radioprotection et de Sûreté Nucléaire) étudie les filtres THE (Très Haute Efficacité) plissés qui sont l'un des dispositifs permettant assurer la sécurité de l'exploitation nucléaire. Pour éviter les rejets dans l'environnement, la compréhension du comportement des filtres en particulier dans la situation accidentelle doit être aussi exhaustive que possible. L'accident le plus probable et le plus pénalisant pour les dispositifs de confinement est l’incendie qui conduit à une production massive de particules de suie. Dans ce cas, le colmatage des filtres est un problème qui doit être pris en compte. Jusqu'à présent, une corrélation empirique a été développée pour prédire l'augmentation de perte de charge. Toutefois, le caractère empirique de cette corrélation ne permet pas son utilisation dans toutes les situations. Une compréhension phénoménologique et un modèle de colmatage est alors nécessaire. Le travail de thèse qui suit vise à lier l'évolution de la perte de charge à des observations physiques pour chaque étape du colmatage. Pour ce faire, l'étude a été divisée en deux parties. La première se focalise sur le comportement du filtre plan en mesurant la pénétration de particules à l'intérieur du medium et la porosité du dépôt formé sur sa surface. La deuxième partie consiste en une expérience à petite échelle basée sur un seul pli. L'accumulation de particules à l'intérieur du pli a été directement observée, de plus, la déformation du pli ainsi que les écoulements d'air dans le pli (en utilisant une méthode de PIV) ont été mesurés. Au cours de ces expériences, la perte de charge a été mesurée et les paramètres mesurés ont été liés à l'évolution de la perte de charge. La finalité est de construire un modèle analytique simple afin de prédire l'évolution de la perte de charge des filtres en fonction de la masse déposée, des caractéristiques de l'aérosol et des conditions aérauliques. La principale perspective ouverte par ces résultats est la validation des modèles numériques complets pour surmonter les limites expérimentales. Le prolongement logique de ce travail sera l'étude du comportement d'un filtre colmaté soumis à des contraintes de température, d’humidité et aux agressions chimiques de produits de combustion / In nuclear facilities, airborne particles are the vector of most of the radiological contamination. For this reason, pleated HEPA filters are one of the containment devices which are actively studied by the IRSN (Institut de Radioprotection et de Sûreté Nucléaire) to ensure the safety of nuclear exploitation. To avoid contamination of the environment, the understanding of the behavior of the filters especially in accidental situation has to be as exhaustive as possible. The most probable accident and the most penalizing for the containment devices is fire which leads to a massive soot particle production. In this case, the clogging of the filters is a problematic which has to be taken into account. Up to now, an empirical correlation has been developed to predict the pressure drop increase. The empirical nature of this correlation doesn’t allow its use in all situations. A phenomenological understanding and model of the clogging is then necessary. The following PhD work aims to reduce the pressure drop evolution to physical observations for each step of the clogging in order to model it on the most physical basis as possible. To do so, the study has been divided in two parts. The first one focusing on the behavior of flat filter by measuring the penetration of particles inside the medium and the porosity of the deposit formed on its surface. In the second part a small scale experiment based on a single pleat has been developed. Accumulation of the particles inside the pleat has been directly observed, deformation of the pleat as well as airflow in the pleat (using a PIV method) has been measured. During these experiments, pressure drop has been monitored and the measured parameters have been linked to the pressure drop evolution. Finality is to build a simple analytical model to predict the pressure drop evolution of the filters as a function of the deposited mass, the aerosol characteristics and the ventilation conditions. The main perspective opened by these results is the validation of complete numerical models to overcome the experimental limits. The logical extension of this work will be the study of the interaction of a clogged filter with temperature, air moisture and chemical aggression

Homogeneous hydrogels made of an interpenetrating network of poly(N-isopropylacrylamide) (PNIPAm) and poly(acrylic acid) (PAAc) are synthesized by a two-step process; first making PNIPAm hydrogels and then interpenetrating acrylic acid throughout the hydrogel through polymerization. The kinetic growth of the IPN is plotted and an equation is fitted to the data. When diluted to certain concentrations in water, the hydrogels show reversible, inverse thermal gelation at about 34°C. This shows unique application to the medical field, as the transition is just below body temperature. A drug release experiment is performed using high molecular weight dyes, and a phase diagram is created through observation of the purified, concentrated gel at varying concentrations and temperatures.

Um dos maiores desafios da Implantodontia é manter a osseointegração e a saúde dos tecidos peri-implantares após a instalação da prótese. Para que uma reabilitação sobre implantes tenha longevidade é necessário que se realize a manutenção da saúde dos tecidos peri-implantares. Existe uma relação direta entre o acúmulo de biofilme e a presença da inflamação desses tecidos, denominada mucosite. Essa condição pode evoluir para uma peri-implantite. A proposta deste estudo foi encontrar uma solução preventiva às doenças peri-implantares, através do controle do biofilme. Avaliou-se a ação antibacteriana de três tipos de revestimentos nanoestruturados com prata aplicados à superfície de discos de titânio frente a cepas de microrganismos peri-implanto-patogênicos. Após determinado o melhor revestimento, analisou-se, também, se a quantidade de prata (3 ou 6 camadas) melhorava sua ação antimicrobiana. Foram confeccionados discos de titânio divididos em 4 grupos: titânio sem deposição (controle), titânio com deposição de solução coloidais de prata e sílica (Si02), titânio com deposição de solução coloidal hidrotermalizada de prata e dióxido de titânio (TiAg) e titânio com deposição de solução hidrotermalizada somente com dióxido de titânio (TiAa). Testou se a efetividade da atividade antimicrobiana dos revestimentos estudados por meio da contagem das colônias bacterianas, encontradas na superfície das placas de ágar sangue. Para permitir uma contagem correta do crescimento das colônias, realizou se diluição seriada e, após incubação a 37°C em anaerobiose, a contagem do número de colônias e, posteriormente, o cálculo das unidades formadoras de colônia (UFC/mL). Após determinação do melhor revestimento, foram desenvolvidos biofilmes monoespécie sobre discos de titânio com 3 e 6 camadas do revestimento SiO2, além dos grupos controle positivo (C.positivo) e negativo (C.negativo), utilizando as cepas Streptococcus gordonii. A atividade microbiana nos biofilmes foi determinada pelo método de XTT. Utilizou-se três discos de cada grupo por teste (triplicata) e realizado a leitura em espectrofotômetro à 450 nm e 492 nm. Os resultados obtidos com cepa de A. actinomycetemcomitans, apresentaram diferença estatística (p<= 0,01) entre o grupo controle (branco) e os grupos teste. Observou-se um maior número de bactérias A.a na superfície branca quando comparado com as superfícies nanoestruturadas com prata, sendo que o grupo SiO2 foi o que apresentou melhor resultado. Notou-se, também, que houve uma maior quantidade da bactéria P.gingivalis na superfície dos discos brancos quando comparado com os grupos com revestimentos nanoestruturados com prata. As bactérias S.aureus e F.nucleatum , porém, não apresentaram redução nos discos com filmes nanoestruturados quando comparados ao disco sem revestimento. Os discos com 6 camadas do revestimento SiO2 apresentaram eficiência semelhante a clorexidina 0,12%, na redução do biofilme da S.gordonii. Conclui-se que os revestimentos nanoestruturados com partículas de prata foram efetivos na redução de UFC/ml das bactérias A. actinomycetemcomitans e P.gingivalis, com o melhor resultado observado com revestimento SiO2. A concentração da prata interferiu positivamente nos resultados com a bactéria S.gordonii. / One of implantology\'s major challenge is to maintain the osseointegration and health of the peri-implant tissues after the installation of the prosthesis. To ensure implant rehabilitation\'s longevity it is necessary to maintain the health of the peri-implant tissues. There is a direct relationship between the accumulation of biofilm and the presence of inflammation of these tissues, called mucositis. This condition can progress to peri-implantitis. The purpose of this study was to find a preventive solution to peri-implant diseases through biofilm control. For this, the antibacterial action against strains of peri-implant-pathogenic of three types of nanostructured coatings with silver applied to the surface of titanium discs microorganisms was evaluated. After determining the best coating, it was also analyzed whether the amount of silver (3 or 6 layers) improved its antimicrobial action. Titanium disks were divided into 4 groups: titanium without deposition (control), titanium with deposition of colloidal solution of silver and silica (SiO2), titanium with deposition of colloidal hydrothermalized solution of silver and titanium dioxide (TiAg) and titanium with deposition of a hydrothermal solution only with titanium dioxide (TiAa). The effectiveness of the coatings was tested by counting the bacterial colonies found on the surface of the blood agar plates. In order to allow a correct colony count, a serial dilution was performed and, after incubation at 37 ° C in anaerobiosis, counting the number of colonies and, later, calculating the colony forming units (CFU / mL). After determination of the best coating, monospecies biofilms were prepared on 3 and 6 layer titanium discs of the SiO2 coating, in addition to the positive control (C.positive) and negative (negative) groups, using Streptococcus gordonii strains. The microbial activity in biofilms was determined by the XTT method. Three disks of each group were used per test (triplicate) and the spectrophotometer read at 450 nm and 492 nm. The results obtained with A. actinomycetemcomitans strain presented a statistical difference (p<=0.01) between the control group (blank) and the test groups. A higher number of A.a bacteria was observed on the blank surface when compared to the nanostructured surfaces with silver, and the SiO2 group showed the best results. It was also noted that there was a greater amount of P.gingivalis bacteria on the surface of the blank discs when compared to the groups with nanostructured coatings with silver. The bacteria S. aureus and F. nucleatum, however, did not present reduction in the discs with nanostructured films when compared to the disc without coating. The 6- layer discs of the SiO2 coating presented similar efficiency to 0.12% chlorhexidine in reducing the S. gordonii biofilm. We concluded that nanostructured coatings with silver particles were effective in reducing CFU/ml of A. actinomycetemcomitans and P.gingivalis bacteria and the best result was observed with SiO2 coating. The concentration of silver interfered positively decreasing S.gordonii bacteria number.

O infarto agudo do miocárdio (IAM) é a principal causa de mortalidade mundial. O IAM é acompanhado de remodelamento cardíaco, caracterizado por alterações gênicas, moleculares e celulares, com consequentes alterações no tamanho, forma e função do coração, e resultante disfunção ventricular e insuficiência cardíaca. Evidências experimentais e clínicas indicam que a prevenção ou o tratamento do remodelamento cardíaco beneficiam a função ventricular. A LDE é uma nanopartícula lipídica, com estrutura semelhante à lipoproteína de baixa densidade (LDL). A LDE tem a capacidade de se concentrar em células com superexpressão de receptores de LDL, como em processos proliferativos e inflamatórios, sendo utilizada com um direcionador de fármacos a sítios específicos. Nosso laboratório demonstrou que o tratamento com metotrexato (MTX), um fármaco antiproliferativo e imunossupressor, associado à LDE reduziu acentuadamente as lesões ateroscleróticas na aorta de coelhos submetidos à dieta hipercolesterolêmica. Esses resultados nos levaram à hipótese de que a LDE-MTX possa ser utilizada para minimizar o processo inflamatório pós-IAM, determinante para o remodelamento cardíaco, e seus efeitos deletérios. O objetivo do trabalho foi investigar o efeito do tratamento da LDE-MTX sobre o remodelamento cardíaco em ratos submetidos ao IAM. Ratos machos Wistar (300-400g) foram submetidos ao modelo cirúrgico de IAM ou à cirurgia fictícia (SHAM). Os grupos foram divididos entre: SHAM (solução fisiológica), IAM-LDE, IAMMTXc (metotrexato comercial), IAM-LDE-MTX. Os animais foram tratados uma vez por semana na dose de 1 mg/kg intraperitonealmente, por 6 semanas. Após 24 horas do IAM e ao final do seguimento, foi realizado o ecocardiograma. O coração, o pulmão, o fígado e os rins foram coletados para obtenção do peso relativo dos órgãos. O tamanho do IAM foi estimado pela média dos tamanhos dos IAM externo e interno. A avaliação da necrose dos miócitos, processo inflamatório, diâmetro dos miócitos e fibrose miocárdica nas regiões subendocárdica (SE) e intersticial (INT) foi realizada na região remota ao IAM. Marcadores de estresse oxidativo, inflamação, fibrose, angiogênese e os receptores de lipoproteínas foram quantificados por PCR em tempo real. O tratamento com LDE-MTX diminuiu a dilatação do VE, hipertrofia cardíaca, volumes sistólicos e diastólicos, espessura do septo interventricular e da parede posterior e massa do VE, comparado aos grupos IAM-LDE e IAM-MTXc. Além disso, houve uma melhora de aproximadamente 40% da função sistólica do VE em relação aos demais grupos IAM. O tratamento com LDE-MTX não alterou a função diastólica. O peso relativo do coração e do pulmão foi menor no grupo IAM-LDE-MTX quando comparado ao IAM-LDE. Na histomorfometria, houve diminuição no tamanho do infarto no grupo IAM-LDE-MTX quando comparado com IAMLDE. A necrose, infiltrado inflamatório e fração de volume do colágeno nas regiões INT e SE foram menores no IAM-LDE-MTX em relação aos grupos IAM-LDE e IAM-MTXc, assim como o diâmetro dos miócitos. A expressão gênica dos marcadores de estresse oxidativo e fibrose foi menor no grupo IAM-LDE-MTX quando comparado ao grupo IAM-MTXc. Com relação à inflamação, o grupo IAM-LDE-MTX apresentou menor expressão do gene para TNF-alfa quando comparado aos grupos IAM-MTXc e SHAM. No que se refere ao receptor de lipoproteína, nos grupos IAM-LDE-MTX houve menor expressão do gene para receptor de lipoproteína de baixa densidade (LDLR) quando comparado ao grupo tratado com MTXc. Não foi observada toxicidade em nenhum grupo. Os resultados deste estudo indicam que o tratamento com LDE-MTX melhora significantemente a função cardíaca e atenua o remodelamento cardíaco em modelo experimental cirúrgico para IAM / Acute myocardial infarction (AMI) is the main cause of worldwide mortality. AMI is accompanied by cardiac remodeling, characterized by genetic, molecular and cellular alterations, with consequent changes in the size, shape and function of the heart, resulting in ventricular dysfunction and heart failure. Experimental and clinical evidence indicate that prevention or treatment of cardiac remodeling benefits the ventricular function. LDE is a lipid nanoparticle with a structure similar to low density lipoprotein (LDL). LDE has the ability to concentrate in cells with overexpression of LDL receptors, such as in proliferative and inflammatory processes, and is used with a drugtargeting agent at specific sites. Our laboratory demonstrated that the treatment with methotrexate (MTX), an antiproliferative and immunosuppressive drug, associated to LDE markedly reduced atherosclerotic lesions in aorta of rabbits submitted to the hypercholesterolemic diet. These results led us to the hypothesis that LDEMTX could be used to minimize the post-AMI inflammatory process, determinant for cardiac remodeling, and their deleterious effects. The aim of this study was to investigate the effect of LDE-MTX treatment on cardiac remodeling in rats submitted to AMI. Male Wistar rats (300-400g) were submitted to the surgical model of AMI or Sham surgery. The groups were divided into: SHAM (saline solution), AMI-LDE, AMI-MTXc (commercial methotrexate), AMI-LDE-MTX. The animals were treated once a week at a dose of 1 mg/kg intraperitoneally, for 6 weeks. After 24 hours of AMI and at the end of the follow-up, the echocardiogram was performed. The heart, lung, liver and kidneys were collected to obtain the relative weight of the organs. Infaction size was estimated by mean extern and intern size of IAM. Evaluation of myocyte necrosis, inflammatory process, myocyte diameter and myocardial fibrosis in the subendocardial (SE) and interstitial (INT) areas was performed in remote area from AMI. Markers of oxidative stress, inflammation, fibrosis, angiogenesis and lipoprotein receptors were quantified by quantitative real-time PCR. Treatment with LDE-MTX decreased LV dilation, cardiac hypertrophy, systolic and diastolic volumes, interventricular septum and posterior wall thickness and LV mass, compared to AMI-LDE and AMI-MTXc groups. In addition, there was an improvement of approximately 40% of LV systolic function compared to other AMI groups. Treatment with LDE-MTX did not alter diastolic function. The relative weight of the heart and lung were lower in the AMI-LDE-MTX group when compared to the AMI-LDE. In morphometry, infarct size decreased in the AMI-LDE-MTX group when compared to AMI-LDE. Necrosis, inflammatory infiltrate and collagen volume fraction in the INT and SE regions were lower in AMI-LDEMTX than in AMI-LDE and AMI-MTXc groups, as well as the myocyte diameter. The gene expression of oxidative stress and fibrosis markers were lower in the AMI-LDE-MTX group when compared to the AMI-MTXc. Regarding inflammation, the AMI-LDE-MTX group had lower expression of the TNF-alfa gene when compared to the AMI-MTXc group and the SHAM group. As regards the lipoprotein receptor, in the AMI-LDE-MTX there was lower expression of the gene for low-density lipoprotein (LDLR) receptor compared to MTXc treated animals. No toxicity was observed in any groups. The results of this study indicate that treatment with LDE-MTX significantly improves cardiac function and attenuates cardiac remodeling in an experimental surgical model for AMI

O óxido nítrico além de poluidor ambiental, também desempenha diversas funções no organismo, por exemplo, trata-se de uma molécula sinalizadora em diversos processos metabólicos. Por causa disso, a detecção de NO é uma importante ferramenta para a medicina. Assim, existe um significante interesse tanto da indústria como da medicina no desenvolvimento de novos materiais que possam detectar oxido nítrico Os Nanotubos de Carbono de Paredes Múltiplas, intensivamente explorados desde sua descoberta em 1991, são considerados promissores em diversas aplicações devido a sua estrutura única e a possibilidade de realizar modificações as quais influenciam suas propriedades físicas e químicas. Já o ouro, conhecido por sua baixa atividade catalíca quando utilizado na forma cristalina, começou a ter seu poder catalítico explorado a partir de 1985, quando descobriu-se que, se utilizado na forma de pequenas partículas, este comporta-se mais como átomos individuais e torna-se mais catalítico que o ouro cristalino. Assim, o objetivo deste trabalho foi promover a funcionalização dos nanotubos de carbono, o que pode ser confirmado por MEV, FTIR e RAMAN, e, a partir dos grupos funcionais gerados, ancorar nanoparticulas de ouro em suas paredes, a fim de otimizar as propriedades catalíticas do material. O material gerado foi caracterizado morfologicamente e estruturalmente por MEV-FEG, EDX, Raio-X, RAMAN e UV-vis. Já a caracterização eletroquímica foi feita por voltametria cíclica frente ao K4[Fe(CN)6], com o qual foi possível mostrar um aumento na densidade de corrente de pico, o deslocamento do potencial de pico para valores menos positivos e também a diminuição do sobrepotencial, quando comparados o sensor Náfion&reg;/AuNP/MWCNT/GC com o Náfion&reg;/GC, Náfion&reg;/MWCNT/GC e Náfion&reg;/Ouro. O eletrodo proposto foi utilizado na determinação de Óxido Nítrico, em tampão PBS pH 4,4, utilizando a técnica de voltametria de pulso diferencial. A metodologia proposta apresentou um limite de detecção de 2,4x10-10 mol L-1 e um limite de quantificação de 7,9x10-10 mol L-1. Assim, este trabalho mostrou a potencialidade de utilização do eletrodo Náfion&reg;/AuNP/MWCNT/GC como sensor eletroquímico para detecção e quantificação de óxido nítrico. / Nitric oxide (NO) is an environmental polluter, which also plays several roles in the body, for example, as a signaling molecule for many metabolic processes. Because this, detecting NO is an important tool in medicine. As a result, there was significant interest in both industry and medicine in developing new materials that can detect NO. Multiwall carbon nanotubes, that have been intensively explored since its discovery in 1991, are considered promising in many applications due to its unique structure and because it can be easily modified in order to tuning their physical and chemical properties. But the interest in using gold as the catalytic material appeared only in 1985, when was discovered that small particles form of gold behaves as individual atoms and it are more catalytic that crystalline gold. In this way, the objectives of this study were promoted the functionalization of carbon nanotubes - which could be confirmed by SEM, FTIR, Raman - and, with the functional groups generated, anchoring gold nanoparticles in their walls, in order to improve the catalytic properties of such material. The developed material was morphologically and structurally characterized by FEG-SEM, EDX, X-ray, Raman and UV-vis. As well, the electrochemical characterization was performed by cyclic voltammetry in K4[Fe(CN)6] solution. When Nafion&reg;/AuNP/MWCNT/GC sensor was compared with Náfion&reg;/GC, Náfion&reg;/MWCNT/GC and Náfion&reg;/Gold, its show an increase in current density peak, the peak potential displacement to less positive values and also decreased potential difference between the cathodic and anodic peak. The proposed electrode was used in the determination of nitric oxide in PBS buffer pH 4.4, which showed a detection limit of 2,4x10-10 mol L-1 and a quantification limit of 7,9x10-10 mol L-1 using the differential pulse voltammetry. Thus, this study demonstrated the potential use of Nafion&reg;/AuNP/MWCNT/GC electrode as an electrochemical sensor in the nitric oxide detection and quantification.

Les nanoparticules d'argent sont de plus en plus utilisées dans les objets de consommation courante ainsi que dans les dispositifs médicaux pour leur activité biocide, qui est due au relargage d'ions Ag(I) au cours du temps. Le recul sur ces nano-objets et en particulier sur leur innocuité n'est toujours pas suffisant et les études sur leur transformation et leur impact in vivo sont sujets à d’intenses recherches. En effet, le devenir dans l’organisme des macro- et micro-matériaux étudiés classiquement n’est pas le même que celles des nanomatériaux. Les nanoparticules d’argent illustrent bien cette problématique : l’argent soluble injecté par voie intraveineuse est éliminé plus rapidement que la même quantité d’argent injectée sous forme nanoparticulaire. De plus, la concentration en argent retrouvée dans le sang et les organes est dix fois supérieure lorsque les nanoparticules d’argent sont injectées plutôt qu’ingérées. C'est pourquoi le développement de produits implantatoires qui se retrouvent donc en contact direct avec l’organisme, et qui contiennent des nanoparticules d’argent doit prendre en compte les risques associés, ce qui peut se faire par une approche Safer-by-design.Une des composantes principales du développement Safer-by-design concerne la fonctionnalisation des nano-objets. L’affinité des thiolates pour l’ion Ag(I) étant très forte, des ligands thiolés pourraient donc constituer une piste pour la fonctionnalisation des nanoparticules d’argent. Néanmoins, il est connu que les molécules thiolées conduisent à différents comportements allant de la dissolution de la nanoparticule d’argent en ions Ag(I) à la simple passivation de la surface de la nanoparticule ce qui peut entrainer la perte de son activité biocide.Ainsi, l’Ecoconception de Nouveaux Agents Biocides à base de Nanoparticules d’Argent à Enrobage Bio-inspiré avait pour objectif principal de poser les bases conceptuelles du développement d’un agent biocide Safer-by-design constitué de nanoparticules d’argent et de molécules thiolées en se positionnant à l’interface de plusieurs disciplines.Le développement de ce projet a nécessité d’étudier la réactivité de diverses molécules biologiques ou bio-inspirées thiolées avec les nanoparticules d’argent. Ainsi, nous avons mis en évidence l’importance de la pré-organisation architecturale des biomolécules dans la cinétique de dissolution, ainsi que le nombre de thiols libres dans la molécule. Dans le cas de composés induisant la dissolution des nanoparticules, sa cinétique augmente avec le nombre de thiols libres présents sur la molécule, et avec la pré-organisation du site de liaison du métal. Le projet principal de cette thèse a ensuite mené à la preuve de concept recherchée, avec le développement d’un nouvel agent biocide composé de nanoparticules d’argents pontées entre elles par un ligand thiolé tripode symétrique qui est le mime chimique d’un site de liaison d’une métallothionéine. Ces assemblages de nanoparticules se sont montrés actifs contre les bactéries (E. coli) et moins toxiques sur les cellules eucaryotes (HepG2), malgré une entrée dans les cellules similaire. Enfin, un criblage a également été réalisé avec des polyéthylèneglycols possédant un à huit thiols et des longueurs de polymères variables dans le but d’essayer de rationaliser les différences de comportement des nanoparticules d’argent en présence des molécules thiolées. Ce travail, a conduit à l’observation des comportements très variés qui vont permettre d’explorer de nouvelles voies de développements de biocides à base d’assemblages de nanoparticules médiés par des liaisons thiol – Ag(I).L’ensemble de ce travail de thèse a donc permis à la fois un travail très fondamental sur la réactivité des thiols vis-à-vis des atomes d’argent à la surface des nanoparticules et au développement de produits à potentiel applicatif, les assemblages de nanoparticules d’argent qui sont des biocides Safer-by-design. / Silver nanoparticles are increasingly used in everyday consumer goods as well as in medical devices for their biocidal activity, which is due to the release of Ag(I) ions over time. The hindsight on these nano-objects and, in particular, on their safety is still not sufficient and studies on their transformation and their impact in vivo is currently an intense research field. Indeed, the fate in the body of macro- and micro-materials studied classically is not the same as for nanomaterials. The case of the silver nanoparticles illustrates this problem: the soluble silver injected intravenously is eliminated faster than the same amount of silver injected in nanoparticular form. Moreover, the concentration of silver found in the bloodstream and organs is ten times higher when silver nanoparticles are injected rather than ingested. The development of silver nanoparticle-containing implanted devices, that get in direct contact with the body, must thus take into account the related risks. A Safer-by-design approach could be a way to solve this issue.One of the main components of Safer-by-design development is the functionalization of nano-objects. The affinity of the thiolates for Ag(I) ions is very high, which would make thiolated ligands a good tool for silver nanoparticle functionalization. However, it is known that the thiolated molecules lead to different behaviors, ranging from the dissolution of silver nanoparticles into Ag(I) ions to the simple passivation of the surface of the nanoparticles, which leads to the loss of their biocidal activity.The Ecodesign of New Biocidal Agents based on Silver Nanoparticles and Bio-inspired Coating is therefore at the interface of several research areas and its main objective was to lay the conceptual foundations for the development of a Safer-by-design biocidal agent based on the interaction between silver nanoparticles and thiolated molecules.The development of this project required to study the reactivity of various biological or bio-inspired thiolated molecules with silver nanoparticles. First of all, we have highlighted the importance of the architectural pre-organization of biomolecules in the dissolution kinetics, as well as the role of the number of free thiols in the molecule. In the case of molecules inducing the dissolution of the nanoparticles, its kinetics increases with the number of free thiols present on the molecule and with the pre-organization of the metal binding site. In a second time, the main project of this thesis was the development of a proof of concept of a new biocidal agent composed of silver nanoparticles bridged together via a thiolated ligand, which is the chemical mimic of one binding site of a metallothionein. These nanoparticle assemblies were active against bacteria (E. coli) and less toxic than silver nanoparticles on eukaryote cells (HepG2), despite a similar cellular entry. Finally, a screening was performed with polyethylene glycols having two to eight thiols and varying polymer lengths in an attempt to rationalize the differences in the behavior of silver nanoparticles in the presence of the thiolated molecules. This ongoing work leads to various behaviors that will enable to explore novel ways for the development of biocidal based on nanoparticles assemblies mediated by thiol – Ag(I) bonds.Therefore, this overall PhD work allows performing both very fundamental researches concerning the reactivity of thiols with surface silver atoms of the nanoparticles and the development of products with application potential, silver nanoparticle assemblies that are Safer-by-design biocide.

The overall goals of this doctoral dissertation are to provide knowledge of workers' exposure to nanomaterials and to assist in the development of standard methods to measure personal exposure to nanomaterials in workplace environments. To achieve the first goal, a field study investigated airborne particles generated from the weighing of bulk carbon nanotubes (CNTs) and the manual sanding of epoxy test samples reinforced with CNTs. This study also evaluated the effectiveness of three local exhaust ventilation (LEV) conditions (no LEV, custom fume hood and biosafety cabinet) for control of exposure to particles generated during sanding of CNT-epoxy nanocomposites. Particle number and respirable mass concentrations were measured with direct-read instruments, and particle morphology was determined by electron microscopy. Sanding of CNT-epoxy nanocomposites released respirable size airborne particles with protruding CNTs very different in morphology from bulk CNTs that tended to remain in clusters (>1µm). Respirable mass concentrations in the operator's breathing zone were significantly greater when sanding took place in the custom hood (p <0.0001) compared to the other LEV conditions. This study found that workers' exposure was to particles containing protruding CNTs rather than to bulk CNT particles. Particular attention should be placed in the design and selection of hoods to minimize exposure. Two laboratory studies were conducted to realize the second goal. Collection efficiency of submicrometer particles was evaluated for nylon mesh screens with three pore sizes (60, 100 and 180 µm) at three flow rates (2.5, 4, and 6 Lpm). Single-fiber efficiency of nylon mesh screens was then calculated and compared to a theoretical estimation expression. The effects of particle morphology on collection efficiency were also experimentally measured. The collection efficiency of the screens was found to vary by less than 4% regardless of particle morphology. Single-fiber efficiency of the screens calculated from experimental data was in good agreement with that estimated from theory for particles between 40 and 150 nm but deviated from theory for particles outside of this range. New coefficients for the single-fiber efficiency model were identified that minimized the sum of square error (SSE) between the experimental values and those estimated with the model. Compared to the original theory, the SSE calculated using the modified theory was at least threefold lower for all screens and flow rates. Since nylon fibers produce no significant spectral interference when ashed for spectrometric examination, the ability to accurately estimate collection efficiency of submicrometer particles makes nylon mesh screens an attractive collection substrate for nanoparticles. In the third study, laboratory experiments were conducted to develop a novel nanoparticle respiratory deposition (NRD) sampler that selectively collects nanoparticles in a worker's breathing zone apart from larger particles. The NRD sampler consists of a respirable cyclone fitted with an impactor and a diffusion stage containing eight nylon- mesh screens. A sampling criterion for nano-particulate matter (NPM) was developed and set as the target for the collection efficiency of the NRD sampler. The sampler operates at 2.5 Lpm and fits on a worker's lapel. The cut-off diameter of the impactor was experimentally measured to be 300 nm with a sharpness of 1.53. Loading at typical workplace levels was found to have no significant effect (2-way ANOVA, p=0.257) on the performance of the impactor. The effective deposition of particles onto the diffusion stage was found to match the NPM criterion, showing that a sample collected with the NRD sampler represents the concentration of nanoparticles deposited in the human respiratory system.

Porous polyurethane foam was evaluated as a potential replacement substrate for the eight nylon meshes currently being used in the diffusion stage of the Nanoparticle Respiratory Deposition (NRD) Sampler. A semi-empirical particle deposition model and preliminary tests were used to select the dimensions of foam substrate needed to match the collection of the NRD sampler at recommended sampling conditions. The foam substrate consisted of a cylinder nominally 25-mm diameter by 40 mm in depth, housed in a conductive plastic cassette cowl (internal diameter of 23 mm) compatible with the existing NRD sampler. Pristine foam was evaluated for metals content via acid-assisted microwave digestion and inductively coupled plasma-optical emissions spectroscopy (ICP-OES) chemical analysis. Foam collection efficiency was evaluated using salt (NaCl) and metal fume test aerosols in independent tests. Foam collection efficiency was compared to the nanoparticulate matter (NPM) criterion (established to reflect the total deposition in the human respiratory system for particles smaller than 300 nm) and theoretical modeling. The collection efficiency of NaCl particles was similar to the NPM criterion (R2 = 0.98) and the model underestimated the experimental efficiency (R2 = 0.38). Increased collection efficiency of metal fume was observed for particles larger than 70 nm presumably due to increased interception effects of fractal shaped particles. The pressure drop across the pristine foam was 1/12th that of the nylon meshes. Foam and nylon meshes were loaded with metal fume particles to evaluate performance under simulated field conditions. Changes in collection efficiency and pressure drop were used as measures of performance. Foam had substantially lower changes in collection efficiency and pressure drop with ~ 19 mg metal fume loaded compared to the nylon meshes with ~ 3 mg metal fume loaded.