Several self-supported and metal oxide supported cobalt Fisher-Tropsch (FT) catalysts were prepared applying incipient wetness impregnation method. The catalysts were characterized by TPR, adsorption-desorption, XRD, TEM and SEM. The gas products were characterized by GC. The effect of support was investigated. The selfsupported 3D ordered macro-porous (3DOM) Fe-Co and self-supported 2D ordered mesoporous catalyst showed low or no activity under typical F-T reaction conditions. The 3DOM Al2O3 supported cobalt catalyst showed much higher CO conversion and C4+ selectivity than conventional Co/Gamma-Al2O3 catalyst. However, the 3DOM Co/Al2O3 prepared by incorporated method showed no activity. The supported Co/SBA-15 performed better CO conversion than the conventional Co/SiO2. The effects of temperature and time on 3DOM Co/Al2O3 and Co/SBA-15 system were coherent with traditional catalysts. The well-defined structure of 3DOM Al2O3 and SBA-15 may favor to the selectivity of C4+ hydrocarbons product.

Colloidal self assembly is an efficient method for making 3-D ordered nanostructures suitable for materials such as photonic crystals and macroscopic solids for catalysis and sensor applications. Colloidal crystals grown by convective methods exhibit defects on two different scales. Macro defects such as cracks and void bands originate from the dynamics of meniscus motion during colloidal crystal growth while micro defects like vacancies, dislocation and stacking faults are indigenous to the colloidal crystalline structure. This paper analyses the crystallography and energetics of the microscopic defects from the point of view of classical thermodynamics and discusses the strategy for the control of the macroscopic defects through optimization of the liquid-vapor interface. / Singapore-MIT Alliance (SMA)

A contactless method using a novel design of the experimental cell for formation of porous silicon with morphological gradient is reported. Fabricated porous silicon layers show a large distribution in porosity, pore size and depth along the radius of the samples. Symmetrical arrangements of morphology gradient were successfully formulated radially on porous films and the formation was attributed to decreasing current density radially inward on the silicon surface exposed to Triton (R) X-100 containing HF based etchant solution. Increasing the surfactant concentration increases the pore depth gradient but has a reverse effect on the pore size distribution. Interestingly, when dimethyl sulfoxide was used instead of Triton (R) X-100 in the etchant solution, no such morphological gradients were observed and a homogeneous porous film was formed.

Dans cette thèse, des réseaux de nano- et micro-capteurs électrochimiques et opto-électrochimiques sont fabriqués en utilisant la technique de microfabrication « template synthesis ». Dans une première partie, des ensembles de nanoélectrodes (NEEs) sont utilisés comme plate-forme pour obtenir un biocapteur. Les NEEs sont préparés par déposition d’or dans une membrane poreuse en polycarbonate. L’originalité de notre approche a été de modifier la membrane de polycarbonate entourant les NEEs et non les NEEs elles-mêmes. La peroxydase de raifort (HRP) qui est fixée sur un anticorps secondaire a servi comme marqueur. Cette enzyme catalyse la réduction de H2O2 qui est ajouté en solution. En utilisant un système de détection dérivé de l'approche ELISA (Enzyme- Linked Immuno-Sorbants Assay), le récepteur de la protéine HER2 a été pris comme analyte cible. Il s’agit d’une protéine très importante puisqu’elle permet de dépister le cancer du sein. Dans une seconde partie, un réseau ordonné de sondes opto-électrochimiques est développé sur la face distale d’un faisceau de fibres optiques qui a été attaquée sélectivement par voie humide. Une structure macroporeuse est fabriquée en utilisant un cristal colloïdal comme « template ». L’or est ensuite déposé dans les interstices avant de dissoudre les nanoparticules de latex formant le cristal colloïdal. Ce réseau de microcavités macroporeuses a été testé avec succès comme substrat pour des mesures de Raman exalté de surface (SERS). / In this thesis, arrays of nano- and microelectrodes are developed to obtain electrochemical and optoelectrochemical sensors, by using the template synthesis as a microfabrication technique. In the first part, ensembles of nanoelectrodes (NEEs), obtained using a track-etched polycarbonate membrane as template, are functionalised in order to obtain electrochemical immunosensors. A biorecognition chain, antigen-antibody, is immobilized on the wide polycarbonate membrane letting uncovered the gold nanodisk electrodes. A label redox enzyme, linked to the biorecognition chain, is recognized and quantified electrochemically. Two different detection schemes are developed and low protein detection limits are achieved. In the second part, a macroporous micrometer sized opto-electrochemical sensor is developed on the distal face of an imaging fiber (coherent optical fiber bundle). A microwell array is obtained by controlled chemical etching, by exploiting the different chemical composition between cores and clads. Colloidal templates are created inside the microcavities, using polystirene beads of 280 nm. Gold is deposited inside the cavities, filling the void in the colloidal template, exploiting electroless and electrochemical deposition techniques. The gold macroporous structure inside the wells is successfully tested as SERS substrate.

Cultivos de células VERO em microcarregadores porosos de celulose (Cytopore) e porosos de gelatina (Cultispher G) com rendimento celular três vezes maior, foram obtidos em relação às culturas em microcarregadores sólidos de DEAE-dextran (Cytodex tipo 1). No Cytopore e Cultispher G atingimos 1.265 e 1.103 células/microcarregador, respectivamente e no Cytodex 1, 256 células/microcarregador. A concentração celular nos suportes porosos Cytopore aumentou 43 vezes o número de células iniciais, 37,5 vezes no Cultispher G e 17 vezes no Cytodex 1. As culturas de células VERO nos microcarregadores porosos foram utilizadas com êxito para a replicação do vírus rábico (PV/VERO), quando infectadas com MOI de 0,05. Títulos de 104,8 FFD50/mL determinados pelo método de inibição de focos fluorescentes (RFFIT) foram obtidos 96 horas após a infecção. Estudos de microscopia óptica e eletrônica de varredura e transmissão para análise da estrutura destes suportes, mostraram boa colonização celular e a eficiência da replicação viral. A padronização de metodologia para cultura e infecção viral de células VERO nos microcarregadores porosos indica a utilidade destes suportes para produção de antígenos e vacinas virais e a potencialidade do sistema para a obtenção de produtos biotecnológicos em geral. / Cultures of VERO cell on porous cellulose-coated microcarriers (Cytopore) and on porous gelatin-coated (Cultispher G) with a cellular yield 3 times higher, was obtained in relation to DEAE-dextran solid microcarriers (Cytodex type 1). In the cultures on Cytopore and Cultispher G we obtained 1.265 and 1.103 cells/microcarrier, respectively and 256 cells/microcarrier on Cytodex 1. The cell concentration for the Cytopore porous suports increased 43 times from the initial cell number, 37,5 times for the Cultispher G and 17 times for the Cytodex 1. The VERO cell cultures on porous microcarriers were efficiently used for the replication of the rabies virus (PV/VERO), when infected with 0,05 MOI. Titers of 104,8 FFD50/mL determined by the fluorescent focus inhibition method (RFFIT) were obtained 96 hours post-infection. Studies on light microscopy and scanning and transmission eletronic microscopy carried out to analyse the suports structure, showed a good cell population and efficiency of virus infection. The standardization of a methodology for culture and virus infection of VERO cells on porous microcarriers indicate the usefulness of these porous supports to the antigens and viral vaccines production and the potenciality of this system for the attainment of biotechnological products.

A complexidade de desenvolver novas tecnologias para aplicações em reconstituição óssea se deve à necessidade de combinar várias propriedades químicas e físicas para que o material proporcione o desempenho almejado. Particularmente, em aplicações que visam osteogênese, os enxertos sintéticos devem ser bioativos, possuir porosidade com volume, geometria e interconectividade de poros controlados, além de ter boas propriedades mecânicas, dentro de limites relativamente rígidos. Por essa razão, o recobrimento de materiais bioinertes com cerâmicas bioativas se tornou o foco da presente pesquisa. O objetivo desse estudo foi desenvolver um novo método de produção de enxertos cerâmicos com macroporosidade funcionalizada, onde a formação e o revestimento dos poros são realizados em uma única etapa. Foi realizado o estudo de recobrimento com vidro bioativo e fosfato de cálcio. Para isso, agentes porogênicos na forma de grânulos (de 600 &#956m a 2 mm de diâmetro) foram sintetizados pelo método da gelificação de uma solução aquosa de alginato de sódio gotejada em solução de nitrato de cálcio (0,5 M), com incorporação de outros elementos para a formação de biovidro ou fosfato de cálcio. Esses grânulos foram conglomerados a um vidro ou alumina em pó, formando um compósito, que foi tratado termicamente para sinterização e formação de poros. No caso da matriz vítrea, a sinterização ocorreu com cristalização simultânea e concorrente. As cerâmicas resultantes foram caracterizadas por microscopia óptica e eletrônica de varredura, sendo possível observar a formação de macroporos aproximadamente esféricos (de 600 &#956m a 2 mm de diâmetro) revestidos internamente por uma camada de material com possível composição bioativa. / A tough requirement in the manufacture of implants for medicine is to conciliate appropriate mechanical properties and the porosity necessary for bone ingrowth. It is further important to control the fraction, morphology, size, surface to volume ratio and interconnectivity of pores. The difficulty in matching these characteristics is a deterrent for practical applications. High strength materials coated with a bioactive layer can overcome this problem. Therefore, the aim of the present study was to develop a new method for production of implants with functionalized macro porosity on ceramic. The production of a porous glass-ceramic and the internal coating of the pores with a bioactive material were performed in situ. The bioactive glass coating and calcium phosphate coating were studied. In order to achieve this goal, a porogenic agent in the form of beads (from 600 &#956m to 2 mm diameter) were prepared by the gelation of a water solution of sodium alginate into calcium nitrate solution (0.5 M), and incorporation of other components to yield the Bioglass composition or a calcium phosphate. The beads were further mixed with glass or ceramic powder and the assembly was heat treated for sintering. In the case of glass, the sintering occurred with concurrent crystallization. The obtained ceramics were characterized by optical and scanning electronic microscopy, which indicated that the porogenic beads acted successfully as a sacrificial template to produce functionalized macro pores.

Cultivos de células VERO em microcarregadores porosos de celulose (Cytopore) e porosos de gelatina (Cultispher G) com rendimento celular três vezes maior, foram obtidos em relação às culturas em microcarregadores sólidos de DEAE-dextran (Cytodex tipo 1). No Cytopore e Cultispher G atingimos 1.265 e 1.103 células/microcarregador, respectivamente e no Cytodex 1, 256 células/microcarregador. A concentração celular nos suportes porosos Cytopore aumentou 43 vezes o número de células iniciais, 37,5 vezes no Cultispher G e 17 vezes no Cytodex 1. As culturas de células VERO nos microcarregadores porosos foram utilizadas com êxito para a replicação do vírus rábico (PV/VERO), quando infectadas com MOI de 0,05. Títulos de 104,8 FFD50/mL determinados pelo método de inibição de focos fluorescentes (RFFIT) foram obtidos 96 horas após a infecção. Estudos de microscopia óptica e eletrônica de varredura e transmissão para análise da estrutura destes suportes, mostraram boa colonização celular e a eficiência da replicação viral. A padronização de metodologia para cultura e infecção viral de células VERO nos microcarregadores porosos indica a utilidade destes suportes para produção de antígenos e vacinas virais e a potencialidade do sistema para a obtenção de produtos biotecnológicos em geral. / Cultures of VERO cell on porous cellulose-coated microcarriers (Cytopore) and on porous gelatin-coated (Cultispher G) with a cellular yield 3 times higher, was obtained in relation to DEAE-dextran solid microcarriers (Cytodex type 1). In the cultures on Cytopore and Cultispher G we obtained 1.265 and 1.103 cells/microcarrier, respectively and 256 cells/microcarrier on Cytodex 1. The cell concentration for the Cytopore porous suports increased 43 times from the initial cell number, 37,5 times for the Cultispher G and 17 times for the Cytodex 1. The VERO cell cultures on porous microcarriers were efficiently used for the replication of the rabies virus (PV/VERO), when infected with 0,05 MOI. Titers of 104,8 FFD50/mL determined by the fluorescent focus inhibition method (RFFIT) were obtained 96 hours post-infection. Studies on light microscopy and scanning and transmission eletronic microscopy carried out to analyse the suports structure, showed a good cell population and efficiency of virus infection. The standardization of a methodology for culture and virus infection of VERO cells on porous microcarriers indicate the usefulness of these porous supports to the antigens and viral vaccines production and the potenciality of this system for the attainment of biotechnological products.

A complexidade de desenvolver novas tecnologias para aplicações em reconstituição óssea se deve à necessidade de combinar várias propriedades químicas e físicas para que o material proporcione o desempenho almejado. Particularmente, em aplicações que visam osteogênese, os enxertos sintéticos devem ser bioativos, possuir porosidade com volume, geometria e interconectividade de poros controlados, além de ter boas propriedades mecânicas, dentro de limites relativamente rígidos. Por essa razão, o recobrimento de materiais bioinertes com cerâmicas bioativas se tornou o foco da presente pesquisa. O objetivo desse estudo foi desenvolver um novo método de produção de enxertos cerâmicos com macroporosidade funcionalizada, onde a formação e o revestimento dos poros são realizados em uma única etapa. Foi realizado o estudo de recobrimento com vidro bioativo e fosfato de cálcio. Para isso, agentes porogênicos na forma de grânulos (de 600 &#956m a 2 mm de diâmetro) foram sintetizados pelo método da gelificação de uma solução aquosa de alginato de sódio gotejada em solução de nitrato de cálcio (0,5 M), com incorporação de outros elementos para a formação de biovidro ou fosfato de cálcio. Esses grânulos foram conglomerados a um vidro ou alumina em pó, formando um compósito, que foi tratado termicamente para sinterização e formação de poros. No caso da matriz vítrea, a sinterização ocorreu com cristalização simultânea e concorrente. As cerâmicas resultantes foram caracterizadas por microscopia óptica e eletrônica de varredura, sendo possível observar a formação de macroporos aproximadamente esféricos (de 600 &#956m a 2 mm de diâmetro) revestidos internamente por uma camada de material com possível composição bioativa. / A tough requirement in the manufacture of implants for medicine is to conciliate appropriate mechanical properties and the porosity necessary for bone ingrowth. It is further important to control the fraction, morphology, size, surface to volume ratio and interconnectivity of pores. The difficulty in matching these characteristics is a deterrent for practical applications. High strength materials coated with a bioactive layer can overcome this problem. Therefore, the aim of the present study was to develop a new method for production of implants with functionalized macro porosity on ceramic. The production of a porous glass-ceramic and the internal coating of the pores with a bioactive material were performed in situ. The bioactive glass coating and calcium phosphate coating were studied. In order to achieve this goal, a porogenic agent in the form of beads (from 600 &#956m to 2 mm diameter) were prepared by the gelation of a water solution of sodium alginate into calcium nitrate solution (0.5 M), and incorporation of other components to yield the Bioglass composition or a calcium phosphate. The beads were further mixed with glass or ceramic powder and the assembly was heat treated for sintering. In the case of glass, the sintering occurred with concurrent crystallization. The obtained ceramics were characterized by optical and scanning electronic microscopy, which indicated that the porogenic beads acted successfully as a sacrificial template to produce functionalized macro pores.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Immobilization of enzymes provides advantages such as increased in: stability, level of process control, yield and purity of the final product, in addition to allowing the use of different reactor configurations. In this study, two types of support, an organic polymer (polimetilmetacrilato- PMMA) and other inorganic (silica) were used for the immobilization of lipase Candida antarctica type B (CALB). Different alcohols (ethanol, iso-propanol, n-butanol) were evaluated as agents for optimization of the immobilization process, the concentrations of 5, 10 and 15% (volume of alcohol à 100 / solution volume immobilization). Immobilization of PMMA was conducted using two different protocols here denominated first and second protocol generation. The best results of hydrolytic activity and esterification to the derivative of the first generation was 3,91  0,09 UpNPB/g. of catalyst e 409,5  19,7 Uoleic acid/g. of catalyst, respectively. When using the protocol of the second generation, the best results were obtained when aa immobilization was carried out in the presence of 5% Triton X-100 2 mM, rising rate of the esterification reaction between the derivatives studied was highly significant with a higher ratio of 3,81 times to the derivative prepared with Triton X-100. The CALB was also immobilized for the macroporous silica support (IB S60S - Chiralvision), the activate agent used was Triethoxy(octyl)silane (C8-TEOS). The results observed for immobilization in the presence of 5% n-butanol were the best for both hydrolytic activity, being four times higher than the activity for the immobilized derivative without alcohol, as for the esterification activity was 985,1  5,6 Uoleic acid/g. of catalyst . All observed derivatives supported on silica and PMMA reached a level conversion for equilibrium esterification reaction for a reaction time of 24 h the best results varying between 80 to 90%. / A imobilizaÃÃo das enzimas traz vantagens como: aumento da estabilidade, do nÃvel de controle do processo, do rendimento e da pureza do produto final, alÃm de possibilitar o uso de reatores de diferentes configuraÃÃes. Neste trabalho, dois tipos de suporte, um polÃmero orgÃnico (polimetilmetacrilato- PMMA) e outro inorgÃnico (sÃlica), foram utilizados para a imobilizaÃÃo da lipase do tipo B de Candida antarctica (CALB). Diferentes Ãlcoois (etanol, iso-propanol, n-butanol) foram avaliados como agentes de otimizaÃÃo do processo de imobilizaÃÃo, nas concentraÃÃes de 5, 10 e 15 % (volume de Ãlcool Ã100 / volume da soluÃÃo de imobilizaÃÃo). A imobilizaÃÃo em PMMA foi conduzida atravÃs de dois protocolos diferentes, aqui denominados de protocolo de primeira e segunda geraÃÃo. Os melhores resultados de atividade hidrolÃtica e de esterificaÃÃo para o derivado de primeira geraÃÃo foi de 3,91  0,09 UpNPB/g. de catalisador e 409,5  19,7 UÃc. olÃico/g. de catalisador, respectivamente. Quando se utilizou o protocolo de segunda geraÃÃo, melhores resultados foram obtidos quando a a imobilizaÃÃo foi conduzida na presenÃa de n-butanol 5 % e Triton X-100 2mM; o aumento da velocidade da reaÃÃo de esterificaÃÃo entre os derivados estudados foi bastante significativo, sendo 3,8 vezes maior para o derivado preparado com Triton X-100. A CALB foi imobilizada tambÃm para o suporte sÃlica macroporosa (IB S60S - Chiralvision), o agente ativante utilizado foi o octiltrietoxisilano (C8-TEOS). Os resultados observados para imobilizaÃÃo na presenÃa de n-butanol 5 % foram os melhores tanto para a atividade hidrolÃtica, sendo quatro vezes maior que a atividade para o derivado imobilizado sem Ãlcool, quanto para a atividade de esterificaÃÃo que foi de 985,1  5,6 UÃc. olÃico/g. de catalisador. Todos os derivados observados suportados em PMMA e sÃlica atingiram um patamar de conversÃo do equilÃbrio para reaÃÃo de esterificaÃÃo por um perÃodo de reaÃÃo de 24 h com os melhores resultados variando entre 80 a 90%.

The key tool for tissue engineering is the scaffold that supports cells for new tissue growth. Materials used for creating scaffolds are based on polymeric materials, carbon nanofibers, ceramics, and metals and their alloys. In my thesis, I describe the synthesis and characterization of new biodegradable hydrogels containing biodegradable crosslinks and biodegradable nanofibrous materials intended for scaffolds for tissue engineering. I also describe the preparation of macroporous hydrogels intended for neural tissue healing. In the first portion of this thesis, I examine a hydrogel based on a pH- responsive crosslinker. This hydrogel is stable at basic and neutral pHs but is degradable at pH < 7.4. The degradation rate of this hydrogel can be tailored. This hydrogel can be utilized as an esophageal stent or as a targeted drug release system in the stomach. The second portion of this thesis focuses on a biodegradable hydrogel designed for neural tissue repair. This hydrogel is composed of copolymers of N-(2- hydroxypropyl)methacrylamide and a newly synthesized biodegradable crosslinker based on 6,6'-dithiodinicotinic acid. This hydrogel can be stored in a neutral environment without degradation. Its long-term storage capability is another great advantage for clinical applications. During storage,...