This work focused on the design of functional capsules made of chemically modified polysaccharides. The layer-by-layer capsules have attracted great interest due to their Indeed, as an advanced multifunctionality which can be advantageously used for pharmaceutical and biomedical applications. Polysaccharides, which are generally biocompatible and biodegradable, are very attractive materials for the construction of bio-related multilayer systems. Considering the intrinsic antibacterial properties of chitosan (CHI), this polysaccharide was selected and quaternized to prepare in physiological conditions contact-killing capsules by combination with hyaluronic acid (HA). The relationship between the antibacterial activity of the quaternized chitosan derivatives (QCHI) and that of QCHI-based capsules was investigated. Then, in order to encapsulate small hydrophobic drugs within the wall of capsules, alkylated derivatives of HA were used as the negatively charged partner of QCHI for the capsules formation. The encapsulation of the hydrophobic dye, nile red (NR), in the hydrophobic shell of capsules was determined. At last, to release the payload under mild conditions was studied by synthesizing rapidly degradable capsules composed of hydrolysable cationic dextran derivatives and HA. The degradation of the layer-by-layer assemblies, both multilayer films and microcapsules is discussed. / Ce travail de thèse porte sur la conception de capsules fonctionnelles à base de polysaccharides chimiquement modifiés. Les capsules couche par couche connaissent actuellement un essor important lié à leur multifonctionnalité pouvant être avantageusement mise à profit dans les domaines pharmaceutique et biomédical. Les polysaccharides, généralement biocompatibles et biodégradables, constituent des matériaux de choix pour la construction de systèmes multicouches. Compte tenu des propriétés antibactériennes intrinsèques du chitosane (CHI), ce polysaccharide a été choisi puis quaternisé afin de préparer dans des conditions physiologiques des capsules par complexation avec l'acide hyaluronique (HA), capables de tuer les bactéries par simple contact. La relation entre l'activité antibactérienne des dérivés quaternisés du chitosane (QCHI) et celle des capsules préparées à partir de QCHI a été étudiée. En outre, afin d'encapsuler des médicaments hydrophobes dans la paroi des capsules, des dérivés alkylés du HA ont été utilisés en tant que partenaire chargé négativement du QCHI pour la formation des capsules. L'encapsulation d'une sonde fluorescente hydrophobe, le nile rouge (NR), dans le réservoir hydrophobe des capsules a été réalisée avec succès. Enfin, pour libérer des médicaments encapsulés dans des capsules dans des conditions douces, des capsules rapidement dégradables comprenant des dérivés cationiques hydrolysables du dextrane et de HA ont été préparées. La dégradation des assemblages couches par multicouches a été analysée par différentes approches à la fois à partir de capsules et de films plans.

The role of energy as a stimulant for economic growth and environmental sustainabilityof any nation has made the focus on green fuels, including fermentative hydrogen (bioH2) andmethane (bioCH4), to be a priority for the World’s policy makers. Nigeria, as the most populousAfrican country, with worsening energy crisis, can benefit from the introduction of the bioH2 andbioCH4 technologies into the country’s energy mix, since such technologies have the potential ofgenerating energy from organic wastes such as fruit waste.Fruit waste was studied in detail in this work because of its great economic andenvironmental potential, as large quantities of the wastes (10–65% of raw fruit) are generatedfrom fruit consumption and processing. Meanwhile, bioH2 and bioCH4 productions involvinganaerobic microorganisms in direct contact with organic wastes have been observed to result insubstrate and product inhibitions, which reduce the gas yields and limit the application of thetechnologies on an industrial scale. For example, in this study, the first experimental work todetermine the effects of hydraulic retention times and fruit mixing on bioH2 production fromsingle and mixed fruits revealed the highest cumulative bioH2 yield to be equivalent to 30% ofthe theoretical yield. However, combining the fermentation process with the application ofmembrane encapsulated cells and membrane separation techniques, respectively, could reducesubstrate and product inhibitions of the microorganisms. This study, therefore, focused on theapplication of membrane techniques to enhance the yields of bioH2 and bioCH4 productions fromthe organic wastes.The second experimental work which focused on reduction of substrate inhibition,involved the investigation of the effects of the PVDF membrane encapsulation techniques on thebioH2 and bioCH4 productions from nutrient media with limonene, myrcene, octanol and hexanalas fruit flavours. The results showed that membrane encapsulated cells produced bioCH4 fasterand lasted longer, compared to free cells in limonene. Also, about 60% membrane protectiveeffect against myrcene, octanol and hexanal inhibitions was obtained. Regarding bioH2production, membrane encapsulated cells, compared to free cells, produced higher average dailyyields of 94, 30 and 77% with hexanal, myrcene and octanol as flavours, respectively. The finalpart of the study, which was aimed at reducing product inhibition, involved the study of theeffects of membrane permeation of volatile fatty acids (VFAs) on the bioreactor hydrodynamicsin relation to bioH2 production. The investigation revealed that low transmembrane pressure of104Pa was required to achieve a 3L h-1m-2 critical flux with reversible fouling mainly due to cakelayer formation, and bioH2 production was also observed to restart after VFAs removal.The results from this study suggest that membrane-based techniques could improve bioH2and bioCH4 productions from fermentation media with substrate and product inhibitions.

<p>The design and application of effective drug carriers is a fundamental concern in the delivery of therapeutics for the treatment of cancer and other vexing health problems. Traditionally utilized chemotherapeutics are limited in efficacy due to poor bioavailability as a result of their size and solubility as well as significant deleterious effects to healthy tissue through their inability to preferentially target pathological cells and tissues, especially in treatment of cancer. Thus, a major effort in the development of nanoscopic drug delivery vehicles for cancer treatment has focused on exploiting the inherent differences in tumor physiology and limiting the exposure of drugs to non-tumorous tissue, which is commonly achieved by encapsulation of chemotherapeutics within macromolecular or supramolecular carriers that incorporate targeting ligands and that enable controlled release. The overall aim of this work is to engineer a hybrid nanomaterial system comprised of protein and silica and to characterize its potential as an encapsulating drug carrier. The synthesis of silica, an attractive nanomaterial component because it is both biocompatible as well as structurally and chemically stable, within this system is catalyzed by self-assembled elastin-like polypeptide (ELP) micelles that incorporate of a class of biologically-inspired, silica-promoting peptides, silaffins. Furthermore, this methodology produces near-monodisperse, hybrid inorganic/micellar materials under mild reaction conditions such as temperature, pH and solvent. This work studies this material system along three avenues: 1) proof-of-concept silicification (i.e. the formation and deposition of silica upon organic materials) of ELP micellar templates, 2) encapsulation and pH-triggered release of small, hydrophobic chemotherapeutics, and 3) selective silicification of templates to potentiate retention of peptide targeting ability.</p> / Dissertation

Nous avons optimisé des liposomes thermosensibles, encapsulant un principe actif anticancéreux, le 5-Fluorouracile (5-FU), afin de déclencher sa libération par une hyperthermie locale modérée (39-42°C) induite par des ultrasons focalisés. L'hyperthermie sera appliquée au niveau de la tumeur, afin d'améliorer l’efficacité thérapeutique et de réduire la toxicité systémique. Les liposomes ont été formulés par hydratation du film lipidique en mélangeant la 1,2-dipalmitoyl-sn-glycéro-3-phosphocholine (DPPC) pour sa thermosensibilité à 41,5 ± 0,5°C, le cholestérol (CHOL) pour favoriser la stabilité des liposomes vis-à-vis des composants du sang, et le 1,2-distéaroyl-sn-glycéro-3-phosphoéthanolamine-N-[méthoxy(polyéthylène glycol)-2000] (DSPE-PEG) pour assurer la furtivité de la formulation. Les expériences ont confirmé que les liposomes formulés à base de DPPC/CHOL/DSPE-PEG dans un ratio molaire 90 : 5 : 5 mol% sont thermosensibles. Des liposomes composés du même mélange lipidique dans un rapport 65 : 30 : 5 mol% ont été considérés comme contrôle négatif non thermosensible. L’optimisation de l’encapsulation passive du 5-FU a permis d’obtenir une efficacité d’encapsulation (5-FU encapsulé/5-FU total) de 13%, mais le 5-FU est très faiblement retenu (12%) dans la cavité aqueuse des liposomes du fait du gradient osmotique à la dilution. La rétention du 5-FU a été optimisée (93%) par la technique d’encapsulation active basée sur la complexation intraliposomale du 5-FU avec le complexe cuivre-polyéthylèneimine préalablement encapsulé dans les liposomes. Cette technique a également permis d’améliorer l’efficacité d’encapsulation d’un facteur trois environ (37%), avec un taux de charge (ratio final 5-FU/lipides, mole/mole) de 50% environ. Nous avons alors obtenu des liposomes thermosensibles d'un diamètre hydrodynamique de 65 nm et de charge de surface de -10 mV. Les liposomes non thermosensibles, ont été caractérisés par un diamètre hydrodynamique de 105 nm et une charge de surface de -4,9 mV. La libération du 5-FU déclenchée par une hyperthermie induite par des ultrasons focalisés a été mesurée in vitro. En réponse à une hyperthermie de 42°C, les liposomes thermosensibles libèrent 68% de leur contenu, au bout de 10 min, alors que les liposomes non thermosensibles en libèrent moins de 20%. En outre, la cytotoxicité des liposomes encapsulant le complexe 5-FU-cuivre-polyéthylèneimine a été évaluée vis-à-vis de la lignée cellulaire HT-29 du carcinome colorectal humain. Les résultats ont révélé que les lipides à une concentration de 800 µM ne sont pas cytotoxiques (80% de viabilité). De plus, la complexation du 5-FU n’influence pas sa cytotoxicité ce qui prouve que la toxicité provient du 5-FU et non des excipients. En revanche, l’encapsulation du complexe 5-FU-cuivre-polyéthylèneimine dans les liposomes induit une diminution de la concentration inhibitrice médiane de 115 (solution du complexe) à 49 µM environ, corrélée à leur internalisation cellulaire. La pharmacocinétique chez des souris porteuses d’un modèle de tumeur colorectale HT-29 xénogreffée a montré que les liposomes permettent de prolonger d’un facteur 1,4 la demi-vie plasmatique de distribution du 5-FU. De plus, les aires sous la courbe des concentrations plasmatiques sur 24 h sont 1,9 et 2,9 fois plus élevées lorsque le 5-FU est administré sous forme de liposomes thermosensibles et non thermosensibles, respectivement, par rapport à la solution de 5-FU. Enfin, les liposomes non thermosensibles augmentent significativement d'un facteur 2 l'accumulation du 5-FU dans la tumeur par rapport à la solution de 5-FU. En conclusion, les liposomes thermosensibles développés présentent un fort intérêt pour une application thérapeutique en combinaison avec des ultrasons focalisés. / We optimized thermosensitive liposomes encapsulating an anticancer drug, 5-Fluorouracil (5-FU), in order to trigger the release upon focused ultrasound-mediated mild hyperthermia at the tumor. This approach would improve drug efficacy and would lower side effects. Liposomes were prepared by the lipid hydration method by mixing 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) for its temperature sensitivity at 41.5 ± 0.5°C, cholesterol (CHOL) to promote liposome stability towards blood components, and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG) to confer stealthiness to the formulation. The experiments confirmed that the liposomes formulated with DPPC/CHOL/DSPE-PEG in a molar ratio 90:5:5 mol% are thermosensitive, while liposomes composed of the same lipid mixture in a ratio 65:30:5 mol% were considered non thermosensitive negative control. The optimization of passive encapsulation of 5-FU yielded an encapsulation efficacy (encapsulated 5-FU/total 5-FU) of 13%. 5-FU was, however, very weakly retained (12%) in the aqueous core of liposomes following dilution due to the generation of an osmotic gradient. The retention of 5-FU has been optimized (93%) by the active encapsulation technique based on the intraliposomal complexation of 5FU with copper-polyethylenimine complex encapsulated beforehand into liposomes. This technique also improved 5-FU encapsulation efficacy by 3-fold (37%), yielding a loading efficiency (final drug/lipid ratio, mol/mol) of approximately 50%. The resulting thermosensitive liposomes and non thermosensitive liposomes have a hydrodynamic diameter and a surface charge around 65 nm and -10 mV, and 105 nm and -4.9 mV, respectively. Heat-triggered drug delivery was evaluated using focused ultrasound, and showed a release of 68% of the encapsulated 5-FU from thermosensitive liposomes, within 10 min, whereas release remained below 20% for the non thermosensitive formulation. Furthermore, the cytotoxicity of 5-FU-copper-polyethylenimine complex-loaded liposomes towards HT-29 human colorectal carcinoma cell line was evaluated. Results revealed that lipids at a concentration of 800 µM are not cytotoxic (80% viability). Moreover, 5-FU complexation has no impact on its cytotoxic activity, disclosing that liposomes toxicity arose from 5-FU and not from the excipients. Nevertheless, 5-FU-copper-polyethylenimine complex-loaded liposomes exhibited a lower half maximal inhibitory concentration of 49 µM compared to 115 µM for complex solution. This enhancement of cytotoxicity was attributed to the cellular internalization of liposomes. Pharmacokinetics in mice bearing HT-29 xenograft tumor showed that liposomes can extend the plasma distribution half-life of 5-FU by a factor 1.4. Furthermore, areas under the concentration-time curve over 24 h were higher by 1.9- and 2.9-fold when the drug was encapsulated into thermosensitive and non thermosensitive liposomes, respectively, compared to free 5-Fluorouracil. Finally, non thermosensitive liposomes significantly increased 5-FU accumulation in tumor by 2-fold, compared to 5-FU solution. In conclusion, these 5-FU-loaded thermosensitive liposomes represent valuable carriers to investigate the therapeutic efficacy following focused ultrasound-mediated heat application.

Lactobacillus acidophilus e Bifidobacterium lactis são microrganismos probióticos frequentemente utilizados em alimentos funcionais. No entanto, estes microrganismos devem resistir ao processamento, à estocagem do alimento, e sobreviver à passagem pelo trato-gastrointestinal, para chegarem ativos ao intestino e exercerem seus efeitos benéficos. Uma vez que os probióticos são sensíveis a uma série de fatores, tais como meio ácido, sais biliares e presença de oxigênio, a microencapsulação tem sido estudada com objetivo de protegê-los aos efeitos adversos do ambiente, além de promover a liberação controlada no local de ação do microrganismo, melhorando sua eficiência. Este trabalho teve como objetivo a produção e avaliação de micropartículas lipídicas contendo B. lactis ou L. acidophilus, produzidas por spray chilling, utilizando gorduras de baixo ponto de fusão, tais como gordura de palma e manteiga de cacau, como agente encapsulante. O diâmetro médio e a morfologia das partículas foram avaliados. Ensaios de sobrevivência foram conduzidos com objetivo de avaliar a resistência dos microrganismos ao processo encapsulação, resistência in vitro aos fluidos gástrico e intestinal simulados e estabilidade das células durante 90 dias de armazenamento a -18, 7 e 20 ou 37°C, dependendo da gordura utilizada. As micropartículasapresentaram-se em formato esféricoe com diâmetro médio que pode permitir o fácil escoamento no alimento, sem proporcionar impacto tecnológico negativo.A tecnologia de encapsulação por spray chilling, utilizando gordura de palma e manteiga de cacau, como agentes encapsulantes, proporcionou a obtenção de micropartículas eficientes na proteção dos probióticos frente ao processo de encapsulação e na manutenção da estabilidade das células quando estocados sob congelamento. Entretanto, aeficiência das micropartículas frente aos fluidos gastrointestinais e a estabilidade das células quando estocadas a 7 e 20 ou 37°C variaram de acordo com a gordura utilizada e com o microrganismo encapsulado. As micropartículas lipídicas obtidas são, portanto, uma matriz inovadora para a aplicação de probióticos, de baixo custo e com grande possibilidade de obtenção em escala industrial. O desafio futuro para o presente estudo é a seleção de um agente encapsulante que aumente a estabilidade das células, nas temperaturas ambiente e de refrigeração, a fim de aumentar as possibilidades de aplicação destas microcápsulas em produtos alimentícios. / L. acidophilus and Bifidobacterium lactis are probiotic microorganisms frequently used in food product. However they must remain viable during processing, entire shelf life of product and passing-through the gastrointestinal tract to provide beneficial effects on human health. Since theses microorganisms are sensitive to a series of factors, especially presence of oxygen and acid medium, microencapsulation has been studied as an alternative to increase probiotic cells viability and to provide the controlled release in the site of action, improving their efficiency. The aim of this study was to produce and evaluate lipid microparticles of L. acidophilus or B. lactis produced by spray chilling technology using low melting point fats, such as palm fat and cocoa butter, as the encapsulant agent. The mean diameter and morphology of the microparticles were evaluated. Survival assays were conducted to evaluate the resistance of the microorganisms to the spray chilling process, viability to the in vitro simulated gastric and intestinal fluids and viability during 90 days of storage at -18, 7 and 20/37°C, depending on the fat used. Microparticles presented a spherical shape and mean diameter that allows the flow of material in the food product without conferring technology influence. Spray chilling technology using fat palm or cocoa butter as the encapsulant agent was efficient in protecting the microorganism to the encapsulation process and 90 days of storage at -18°C. However the efficiency of the microparticles on the gastric and intestinal fluids and the cells stability during storage at 7 e 20 or 37°C varied according to the fat and microorganism used. The lipid microparticles seem to be a relatively innovative matrix for the application of probiotics with low costs and possibility of scale up. The future challenge in this study is to choose an encapsulant agent that improves cells resistance and viability at refrigerator and room temperatures to increase the possibility of application of these microcapsules in food products.

La multiplication des résistances aux antibiotiques constitue une grave menace qui nécessite de nouvelles stratégies antimicrobiennes. Le but de ce travail est d'étudier le potentiel des nanocapsules lipidiques (NCLs) pour l'administration de peptides antimicrobiens (PAMs). Les premiers travaux ont porté sur le développement et l'optimisation de NCLs chargées en PAMs. Différentes stratégies d’association ont été testé (adsorption à la surface ou encapsulation dans le coeur de NCLs). Les résultats ont démontré une efficacité d'association comprise entre 20 et 40%, lorsque les peptides sont adsorbés à la surface et plus de 80%,lorsqu’ils sont encapsulés. La deuxième partie s’est concentrée sur l'évaluation de l’activité des complexes PAMs et NCLs ainsi que leur stabilité vis-à-vis des protéases. Les résultats ont montré que l'adsorption entraîne une potentialisation de l'activité antimicrobienne des PAMs, associée à une protection partielle contre la dégradation enzymatique. Inversement, l’encapsulation des PAMs montre une meilleure stabilité aux enzymes, corrélée à une efficacité d'encapsulation supérieure sans amélioration de l'activité antimicrobienne in vitro. Dans une troisième partie, les mécanismes impliqués dans les interactions LNC/PAM ainsi que l'interaction du complexe avec un modèle de membrane bactérienne ont été étudiés. Il a été montré que la structure et la flexibilité des PAMs aux interfaces solide-liquide gouverneraient l'adsorption des peptides à la surface des NCLs, entrainant un changement de leur comportement avec les membranes bactériennes. L’ensemble de ces résultats démontre le potentiel prometteur des NCLs en tant que vecteur de PAMs. / The rapid increase in drug-resistant infections presents an acute problem in the healthcare sector, generating interest in novel antimicrobial strategies. The aim of this work is to explore the potential of lipid nanocapsules (LNCs) for Antimicrobial peptides (AMPs) delivery. Firstly, the experiments were focused on the development and optimization of AMP-loaded LNCs. Different strategies were investigated to deliver AA230,LL37 and DPK060 using LNCs (peptides adsorption atthe surface or encapsulated in the core of modified LNCs). The results demonstrated an association efficiency of 20 to 40%, when peptide is adsorbed, and over 80% encapsulation efficiency, when peptides are encapsulated. The second part concerned the study ofthe influence of peptides loading on their activity and stability against proteases. The results showed that peptides adsorption induced a potentiation of the antimicrobial activity of the native peptides, with a partial protection against proteolytic degradation. Conversely, peptides encapsulation allowed better peptide stability, correlated with higher encapsulation efficiencies and a preservation of the in vitro antimicrobial activity. In a third part, the mechanisms involved in LNC/AMP interactions and the complex interaction with model bacterial membrane have been evaluated. It has shown that structure and flexibility at solid-liquid interfaces govern peptide adsorption on the surface of the LNCs, which in turn is expected to change LNCs properties and interaction with bacterial membranes. Taken together, these results demonstrate the potential of LNCto deliver AMPs as an alternative anti-infective therapy.

Reações de oxidação lipídica são responsáveis pelo desenvolvimento de sabores e odores desagradáveis tornando os alimentos impróprios para consumo, sendo necessário o uso de antioxidantes. O ácido ascórbico (AA) é um antioxidante muito eficaz, que exibe função vitamínica, no entanto é relativamente instável. Com o objetivo de aumentar a estabilidade do AA e, consequentemente, facilitar sua aplicação em produtos alimentícios, os métodos de encapsulação por coacervação complexa e por dispositivos microfluídicos foram testados. Primeiramente foi apresentada a Revisão Bibliográfica no Capítulo 1, e em seguida, a encapsulação por coacervação complexa, como será visto no Capítulo 2. Neste caso, nove tratamentos foram obtidos utilizando-se gelatina e goma arábica como materiais de parede e analisados com relação à morfologia, por microscopia ótica e eletrônica de varredura, umidade, atividade de água, higroscopicidade, solubilidade, potencial zeta, espectroscopia no infravermelho por transformada de Fourier (Ftir), tamanho e distribuição de tamanho de partículas, cor instrumental, eficiência de encapsulação e estabilidade do material encapsulado. No capítulo 3 serão apresentados resultados obtidos na encapsulação do AA pelo método de dispositivos microfluídicos. Cinco tratamentos foram obtidos, sendo analisados com relação à morfologia, por microscopia ótica, eletrônica de varredura e confocal, eficiência de encapsulação, tamanho e distribuição de tamanho de partícula e estabilidade do material encapsulado. A obtenção das microcápsulas de AA pelos dois métodos citados foi viável uma vez que apresentaram altos valores de eficiência de encapsulação e ótima atuação em relação à proteção do AA durante estocagem. Comparando-se os dois métodos, as cápsulas obtidas por dispositivos microfluídicos conferiram melhor estabilidade ao ácido ascórbico, no entanto amostras obtidas por coacervação complexa foram aplicadas em salsicha devido a maior quantidade de AA presente em sua constituição. O efeito da aplicação das microcápsulas nas salsichas foi avaliado durante 40 dias de armazenamento refrigerado como será visto no Capítulo 4. Cinco tratamentos foram elaborados e analisados de acordo com a estabilidade da emulsão cárnea durante o processamento, umidade, atividade de água, alteração do pH, determinação da cor instrumental, perfil de textura instrumental, estabilidade oxidativa pelo método de substâncias reativas ao ácido tiobarbitúrico (TBARS) e aceitação sensorial. A aplicação das microcápsulas de AA em salsicha foi possível sem comprometer a qualidade do produto final. Todos os dados obtidos foram analisados estatisticamente por análise de variância ANOVA e teste de Tukey, ao nível de 5% de significância com auxílio do programa SAS. Os experimentos relacionados à encapsulação por coacervação complexa e aplicação das microcápsulas em salsicha foram realizados no Laboratório de Produtos Funcionais, nas dependências do Departamento de Engenharia de Alimentos da FZEA/USP. Os experimentos relacionados à utilização de dispositivos microfluídicos foram realizados nos laboratórios do professor David A. Weitz, da Escola de Engenharia e Ciências Aplicadas de Harvard, da Universidade de Harvard, Cambridge, Estados Unidos. / Lipid oxidation reactions are responsible for the development of unpleasant tastes and odors making food unfit for consumption. For this reason, the use of antioxidant is necessary. Ascorbic acid (AA) is a very effective antioxidant with vitamin function, however it is relatively unstable. With the aim of increasing the stability of AA and thus improve its application in food products, the methods of encapsulation by complex coacervation and microfluidic devices were tested. First of all the Literature Review is presented in Chapter 1. The encapsulation by complex coacervation can be seen in Chapter 2. For this methodology, nine treatments were obtained using gelatin and gum Arabic as encapsulant agent and analyzed regarding to morphology by optical and scanning electron microscopy, moisture, water activity, hygroscopicity, solubility, Zeta Potential, Fourier transform infrared Spectroscopy (FTIR), particle size and particle size distribution, instrumental color, encapsulation efficiency and stability of the encapsulated material. The results obtained for AA encapsulation by microfluidic device will be presented in Chapter 3. Five treatments were obtained and analyzed regarding to morphology by optical, scanning electron and confocal microscopy, encapsulation efficiency, particle size and particle size distribution and stability of the encapsulated material. The production of AA microcapsules by the two methods mentioned was feasible once that showed high levels of encapsulation efficiency and optimal performance regarding to the protection of AA during storage. Comparing the two methods, the microcapsules obtained by microfluidic device conferred better stability to AA, however samples obtained by complex coacervation were applied in sausage due to the greater amount of AA in its constitution. The effect of the application of microcapsules in sausages was evaluated during 40 days at refrigerated storage as it will be seen in Chapter 4. Five treatments were prepared and analyzed according to the stability of the meat emulsion during processing, moisture, water activity, pH changes, determination of instrumental color, instrumental texture profile, oxidative stability by the method of thiobarbituric acid reactive substances (TBARS) and sensory acceptance. The application of AA microcapsules in sausage was possible without compromising the quality of the final product. All data were statistically analyzed by ANOVA and Tukey test, at 5% of significance with the use of SAS software. The experiments related to encapsulation by complex coacervation and application of microcapsules in sausage were carried out at Laboratory of Functional Products, at Department of Food Engineering, FZEA / USP. The experiments related to the use of microfluidic devices were performed in the laboratories of Professor David A. Weitz, at School of Engineering and Applied Sciences of Harvard, at Harvard University, Cambridge, USA.

This work, within EPSRC LATEST2 (Light Alloys Towards Environmentally Sustainable Transport 2) Programme Grant, is focused on the development of environmentally-friendly corrosion inhibitors, nanocontainers loaded with inhibitors and epoxy coatings for corrosion protection of the aerospace alloy AA 2024-T3. More specifically, the electrochemical techniques of image assisted electrochemical noise, electrochemical impedance spectroscopy, split-cell technique and potentiodynamic polarization were used for the qualitative and quantitative evaluation and characterization of environmentally-friendly corrosion inhibitors on AA 2024-T3. Scanning electron microscopy observations complemented the electrochemical measurements. It was found that the organic inhibitor 2-mercaptobenzothiazole provides excellent corrosion inhibition properties to AA 2024-T3 in 3.5% sodium chloride solution. Among the tested nitrates, cerium nitrate provides the best inhibition performance. The concentration of the nitrate salt is critical in determining the corrosion protection. An excessive concentration of nitrate ions results in the dissolution of copper-containing oxides, increasing the corrosion rate. Different types of core-shell structured nanocontainers were synthesised with the methods of distillation precipitation polymerization, emulsion polymerization and sol-gel. The nanocontainers were characterized by scanning electron and transmission electron microscopy observations. The corrosion inhibitor 2-mercaptobenzothiazole was encapsulated into the nanocontainers. The encapsulation of 2-mercaptobenzothiazole was evaluated with energy dispersive X-ray analysis mapping micrographs from transmission electron microscopy measurements. Epoxy coatings with nanocontainers loaded with 2-mercaptobenzothiazole were applied on AA 2024-T3 for protection against corrosion. The corrosion protection properties of the coatings were evaluated with electrochemical impedance spectroscopy. The results indicated that epoxy coatings provide excellent barrier properties to AA 2024-T3 in the demanding environment of 3.5% sodium chloride solution with low frequency impedance values more than 1 GOhm cm2 for over 4000 hours of testing. Coatings containing nanocontainers loaded with 2-mercaptobenzothiazole tested with an artificial scribe revealed protection of the AA 2024-T3 substrate in the scribed area, decrease of the anodic delamination in the early hours and decrease number of cathodic dark areas after long immersion time. Overall, epoxy coatings with encapsulated inhibitors can be considered as a promising system for potential replacement of hexavalent chromium treatments on aerospace alloy AA 2024-T3.

O trabalho buscou identificar se o intemperismo acelerado Xênon, utilizando a norma ASTM D4452-12, em corantes naturais encapsulados em matriz de sílica pelo processo sol gel com o uso de alcóxidos, conforme descrito pela patente INPI BR 10 2013 0219835, e injetadas em matriz de policloreto de polivinila (PVC) preservam as características de cor original dos corantes. Utilizou-se comparação dos mesmos corantes naturais – carmim, curcuma, índigo e urucum – sem encapsulamento e com encapsulamento, e injetados na mesma matriz de PVC. Executou-se a determinação da variação da cor antes do ensaio de intemperismo e após 126 h, 252 h, 378 h e 504 h em câmara de intemperismo Xênon utilizando-se a norma ASTM D4459-12. Utilizou-se o corante Tartrazina (INS 102) um azo corante sem encapsulamento como comparação do comportamento dos corantes naturais com um corante sintético. Os resultados indicam que não houve proteção da perda da coloração para os corantes naturais encapsulados, sendo a perda de coloração mais acentuada que os não encapsulados. Concluiu-se que é necessário executar alguns cuidados nas fases de encapsulamento dos corantes naturais como: uma dispersão cuidadosa dos corantes naturais e inclusão de um processo de repetição do encapsulamento do xerogel. / The study aimed to identify the Xenon accelerated weathering, using ASTM D4452-12 standards, of natural dyes encapsulated in the silica matrix by the sol-gel process with the use of alkoxides as described by the patent INPI BR 10 2013 0219835, and injected into matrix of polyvinyl chloride (PVC) preserve characteristics of original color of the dye. We used to compare the same natural colors - carmine, turmeric, indigo and annatto - without encapsulation and with encapsulation, and injected into the same matrix of PVC. Performed to determine the change in color before the weathering test after 126 h, 252 h, 378 h and 504 h in Xenon weathering chamber using ASTM D4459- 12 standards. We used the dye Tartrazine (INS 102) an azo dye without encapsulation as a comparison of the behavior of natural dyes with a synthetic dye. The results indicate that there was no protection of natural dyes encapsulated, with the loss of saturation more severe than the non-encapsulated natural dyes. It follows that some care needs to perform the encapsulation stages of natural dyes as a careful dispersion of natural colorants includes a process of repeat the encapsulation of the xerogel.

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / A indústria de petróleo e gás apresenta sérios problemas relacionados à corrosão. Nas petroquímicas e nas instalações de refino de petróleo, as falhas em materiais estão relacionadas com a corrosão, além disso, os processos de corrosão de metais são problemas no mundo, causando ônus em processos industriais e gerando situações de risco como a corrosão de pilares metálicos em pontes ou em fuselagens de aviões. Dentre os meios corrosivos, um muito comum é o meio ácido, que será o meio estudado neste trabalho. Com todos os problemas citados, se faz necessário o estudo de inibidores de corrosão com alta eficiência, estabilidade e que, preferencialmente, não agridam o meio ambiente. Alguns inibidores de corrosão apresentam solubilidade limitada em água, sendo necessária a utilização de alguns solventes não tão amigáveis ao meio ambiente. Então, propôs-se formar um complexo de inclusão para tornar possível a solubilização de inibidores convencionais em solução aquosa, como algumas tioureias, que apresentam solubilidade limitada em água. Essa completa solubilização do inibidor de corrosão orgânico em meio aquoso é possível com a utilização de um aditivo (hospedeiro) capaz de encapsular tais moléculas (convidados) via interações não covalentes, de modo a alcançar o máximo desempenho de inibição. Para a formação do complexo de inclusão foi usado como molécula hospedeira, a &#945; e a &#946; hidroxipropilciclodextrina e como molécula convidada a dibenziltioureia. A intenção foi testar a melhora da ação inibidora da corrosão do aço carbono em meio de HCl 1mol.L-1 com ensaios de perda de massa, de impedância, polarização e microscopia eletrônica de varredura (MEV), além de evidenciar a formação destes complexos de inclusão através da espectroscopia de absorção vibracional no infravermelho, espectroscopia de RMN de 1H, espectroscopia de absorção no Ultra-violeta e análise térmica diferencial (DTA) / The oil and gas industry presents serious corrosion problems. In the petrochemical and oil refining plants, the flaws in materials is related to corrosion, in addition, metal etching processes are problems in the world, causing burdens on manufacturing processes and resulting hazards such as corrosion of metal pillars on bridges or aircraft bodies. Among the corrosive media, a very common is the acidic, which will be the medium studied in this work. With all these problems, it is necessary to study corrosion inhibitors with high efficiency, stability and, preferably, that is environmentally benign.. Some corrosion inhibitors have limited solubility in water, necessitating the use of organic solvents Then, it was proposed the use of an inclusion complex for making possible to dissolve conventional inhibitors in aqueous solution, as some thiourea, which have such limited solubility in water. The complete dissolution of organic corrosion inhibitor in aqueous media would be possible with the use of an additive (host) capable of encapsulating such molecules (guests) via non-covalent interactions in order to reach the maximum inhibition performance. To form the inclusion complex it was used as the host, the &#945; and &#946; hydroxypropyl-cyclodextrin and as the guest to dibenziltioureia. The intention was to test the improvement of the inhibitory performance of carbon steel corrosion in HCl medium 1molL-1 with mass loss test, impedance, polarization and scanning electron microscopy (SEM), and evidence the formation of these inclusion complexes by absorption vibrational infrared spectroscopy, 1 H NMR spectroscopy, spectroscopy of absorption UV and differential thermal analysis (DTA)