Orientador: Oswaldo Luiz Alves / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T03:12:15Z (GMT). No. of bitstreams: 1 Fonseca_LeandroCarneiro_M.pdf: 4937818 bytes, checksum: 780a4e27e390c1034dc79087ec5b5fb2 (MD5) Previous issue date: 2014 / Resumo: Apesar dos tratamentos quimioterápicos vigentes, os principais fármacos antitumorais da atualidade são utilizados em doses limitadas, pois não possuem especificidade no combate às células cancerosas, atingindo também células sadias do corpo humano. As características hidrofóbicas de muitos desses fármacos dificulta ainda mais sua utilização. Nesse aspecto, as nanotecnologias ligadas à química e a biologia oferecem novas maneiras de superar tais barreiras em virtude do desenvolvimento de nanomateriais capazes de transportar o farmaco especificamente ao alvo biológico. No presente Projeto serão desenvolvidos nanocarreadores esféricos de sílica mesoporosa contendo grupos fenila (hidrofóbicos) em seu interior, cuja função é adsorver fármacos hidrofóbicos através de interações do tipo Van Der Walls no interior dos poros desses nanomateriais, mantendo sua integridade físico-química e, liberando-os posteriormente, às células alvo de maneira específica. Para otimização desses sistemas, faz-se necessário funcionalizar a superfície externa das nanopartículas com o polietilenoglicol (PEG), de modo a camuflá-las do sistema imunológico e evitar efeitos biológicos indesejáveis. Portanto, propõe-se nesse Projeto a funcionalização externa das nanopartículas porosas de sílica com PEGs com cadeias poliméricas curtas e longas, avaliar sua influência na hemólise de células vermelhas do sangue e seu comportamento físico-químico em diferentes meios potenciais de aplicação / Abstract: Despite existing chemotherapy treatments, the main antitumor drugs nowadays are used in limited doses because they have no specificity in fighting cancer cells, affecting healthy cells of the human body . The hydrophobic characteristics of many of these drugs further complicates their use. In this context, nanotechnology related to chemistry and biology offer new ways to overcome these barriers due the development of nanomaterials capable of carrying the pharmaco specifically to the biological target. In this Project spherical mesoporous silica nanocarriers will be developed containing phenyl groups ( hydrophobic ) in its interior , whose function is to adsorb hydrophobic drugs inside the pores through interactions like Van Der, maintaining its physical and chemical integrity and subsequently releasing the latter to target cells in a specific manner. To optimize these systems, it is necessary to functionalize the outer surface of the nanoparticles with polyethylene glycol (PEG) in order to camouflage them from the immune system and prevent undesirable biological effects. Therefore, it is proposed the outer functionalization of porous silica nanoparticles with PEG with short and long polymer chains , evaluate its influence on hemolysis of red blood cells and their physical and chemical behavior and potential application in different ways / Mestrado / Quimica Inorganica / Mestre em Química

Orientadores: Ângela Maria Moraes, José Alberto Fracassi da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T03:16:00Z (GMT). No. of bitstreams: 1 RammazzinaFilho_WalterAnibal_M.pdf: 10957404 bytes, checksum: d23a9aea438343039da493db09603556 (MD5) Previous issue date: 2011 / Resumo: O uso de implantes em cirurgias de correção da parede abdominal é freqüentemente necessário. Telas de poli(propileno) podem ser empregadas com sucesso para essa finalidade, possuindo boa aceitação tecidual e baixo custo. O uso deste tipo de biomaterial pode, porém, ocasionar a aderência indesejada entre tecidos e/ou entre órgãos como o fígado e os intestinos e a tela, resultando em dores abdominais, obstrução intestinal e infertilidade. Neste contexto, o objetivo deste trabalho foi o de desenvolver uma estratégia de recobrimento de telas de poli(propileno) enfocando a deposição de soluções de quitosana de massa molar baixa e média e de polietilenoglicol (PEG) de massa molar igual a 1000 Da por electrospinning. Para fins de comparação, telas de poli(propileno) foram alternativamente recobertas por imersão com diferentes soluções combinando quitosana e PEG. Nos estudos de recobrimento via electrospinning, foram avaliadas as variáveis tipo de solvente para a dissolução da quitosana e do PEG, vazão de solução de recobrimento, proporção entre quitosana e PEG, diferença de potencial usada durante a deposição e distância entre a tela e o jato de injeção. As telas recobertas através da imersão em soluções de quitosana a 1% (tanto com a de baixa massa molar quanto a com massa molar média) e em soluções de quitosana misturada ao PEG também com concentração de sólidos total de 1% apresentaram-se satisfatórias para fins de barreira física em cirurgias de hérnia, considerando-se o aspecto, a uniformidade, os valores médios de espessura (de 1140 e 990 mm, respectivamente), a perda de massa em fluido corpóreo simulado (5,1 e 8,9%, respectivamente) e a capacidade de absorção do mesmo fluido (0,76 e 0,59 g/g, respectivamente). Já o recobrimento por electrospinning resultou no depósito de fibras emaranhadas na superfície das telas, que apresentaram, então espessuras finais variando entre 581 e 612 mm, perdas de massa entre 4,9 e 9,2% em fluido corpóreo simulado, capacidade de absorção de 0,17 a 0,36 g/g em fluido corpóreo simulado e diâmetros de fibras de 20,9 a 92,2 mm. O recobrimento via electrospinning resultou em biomateriais menos espessos e com menos massa associada, com bom potencial de uso na aplicação pretendida / Abstract: The use of implants in surgical correction of the abdominal wall is frequently required. Polypropylene meshes can be successfully employed for this purpose, having good tissue acceptance and low cost. The use of this biomaterial, however, can lead to undesired adhesion between tissues and/or between organs such as the liver and intestines and the mesh, resulting in abdominal pain, bowel obstruction and infertility. In this context, the objective of this work was to develop different coatings of polypropylene meshes, focusing on the deposition of solutions of chitosan of low and medium molecular weight and polyethylene glycol (PEG) of molecular weight equal to 1000 Da by electrospinning. For comparison, polypropylene meshes were alternatively coated by immersion in different solutions combining chitosan and PEG. In the studies of coating via electrospinning, the effect of the variables type of solvent for the dissolution of chitosan and PEG, coating solution flow rate, chitosan to PEG mass ratio, the potential difference used during the deposition and the distance between the mesh and the injection jet were evaluated. Meshes coated by immersion in chitosan (both with low and medium molar mass) and PEG solutions with total solids concentration of 1% were satisfactory for purposes of physical barrier in hernia surgery, considering aspect, uniformity, mean thickness (1140 and 990 mm, respectively), mass loss (5.1 and 8.9%, respectively) and the capacity of fluid absorption (0.76 and 0.59 g/g, respectively). Coating by electrospinning resulted in the deposition of entangled fibers on the surface of the meshes, which had final thickness ranging between 581 and 612 mm, losses of mass between 4.9 and 9.2% in simulated body fluid, absorption capacity of 0.17 to 0.36 g/g in the same fluid and fiber diameters from 20.9 to 92.2 mm. Coating the meshes via electrospinning resulted in thinner biomaterials and with less associated mass, with good potential for use in the intended application / Mestrado / Desenvolvimento de Processos Biotecnologicos / Mestre em Engenharia Química

Cell adhesion is the first step of cell response to materials and the extracellular matrix (ECM), and is essential to all cell behaviours such as cell proliferation, differentiation, migration and apoptosis for anchor-dependent cells. Therefore, studies of cell attachment have important implications to control and study cell behaviours. During many developed techniques for cell attachment, the manipulation of surface chemistry is a very important method to control initial cell attachment. To control cell adhesion on a two-dimensional surface is a simple model to study cell behaviours, and is a fundamental topic for cell biology, tissue engineering, and the development of biosensors. From the engineering point of view, the preparation of a material with controllable surface chemistry can help studies of cell behaviours and help scientists understand how surface features and chemistry influence cell behaviours. During the fabrication, the challenge is to create a surface with heterogeneous surface properties in the micro scale and subsequently to guide cell initial adhesion. In order to control cell adhesion in a spatial and temporal manner, a photochemical method to control surface chemistry was employed to control the surface property for cell adhesion in this project. Two photocleavable derivatives of the nitrobenzyl group were tried on two types of surfaces: a model self-assembled monolayer (SAM) with alkanethiol-gold surface and biodegradable chitosan. Reactive functional groups on two different surfaces can be inactivated by covalent binding with these photocleavable molecules, and light can be further introduced into the system as a stimulus to recover their reactivity. By simply applying a photomask with diffe

Zinc oxide (ZnO) is a versatile environmentally benign II-VI direct wide band gap semiconductor with several technologically plausible applications such as transparent conducting oxide in flat panel and flexible displays. Hence, ZnO thin films have to be processed below the glass transition temperatures of polymeric substrates used in flexible displays. ZnO thin films were synthesized via aqueous polymeric precursor process by different metallic salt routes using ethylene glycol, glycerol, citric acid, and ethylene diamine tetraacetic acid (EDTA) as chelating agents. ZnO thin films, derived from ethylene glycol based polymeric precursor, exhibit flower-like morphology whereas thin films derived of other precursors illustrate crack free nanocrystalline films. ZnO thin films on sapphire substrates show an increase in preferential orientation along the (002) plane with increase in annealing temperature. The polymeric precursors have also been used in fabricating maskless patterned ZnO thin films in a single step using the commercial Maskless Mesoscale Materials Deposition system.

Please read the abstract in the section 00front of this document / Dissertation (M Eng (Metallurgical Engineering))--University of Pretoria, 2005. / Materials Science and Metallurgical Engineering / unrestricted

O presente trabalho teve como objetivo avaliar a emissão de metano por cordeiros alimentados em diferentes pastagens tropicais: Panicum maximum cv. IZ-5 (capim aruana) e Cajanus cajan cv. anão (feijão guandu), e suas relações com a composição química destas pastagens. Os trabalhos foram conduzidos na Estação Experimental Agronômica da UFRGS, nos anos de 2015 e 2016. O delineamento experimental foi de blocos completos casualizados com três repetições. O capítulo II relata os resultados da emissão de metano por cordeiros pastejando nos seguintes tratamentos: 1) ARU – somente capim aruana; 2) FG - somente feijão Guandu; 3) AFG – meio piquete com capim aruana, e a outra metade com feijão Guandu. Para avaliação de metano foi utilizado a técnica com marcador SF6 . No experimento do capítulo II, utilizou-se parcela subdividida, sendo a subparcela dois animais testes que receberam polietileno glicol (PEG) para quelar o tanino presente no feijão guandu, e dois que receberam água como controle. As emissões de metano por consumo de matéria seca (EMICONMSDIA) não apresentaram diferença entre os tratamentos, mesmo considerando as dosificações com polietileno glicol (PEG) ou água (P=0,9235). O tratamento FG (P=0,036) apresentou mais altos níveis de taninos condensados do que os demais tratamentos Apesar de diferenças nas suas características químicas, a emissão de metano de cordeiros é semelhante entre pastagens tropicais de capim aruana (Panicum maximum cv. IZ-5), feijão Guandu (Cajanus cajan cv. Anão. Os taninos condensados presentes na forrageira feijão guandu, nas condições experimentais deste trabalho, não demonstraram potencial para contribuir na redução da emissão de metano por cordeiros. No capítulo III, os tratamentos, manejo dos animais e delineamento experimental foram semelhantes ao capítulo II. Os resultados demonstraram que não há uma relação direta entre as características bioquímicas do alimento e a emissão de metano. Essa desassociação entre a emissão de metano e a composição química da pastagem foi constatada tanto quando relacionou-se a emissão por animal (EMI), quanto quando relacionou-se com a emissão por quilograma de matéria seca ingerida (EMICONMSDIA). Conclui-se, então, que não é possível relacionar a emissão de metano de cordeiros com as características químicas das plantas forrageiras tropicais perenes, capim aruana e feijão Guandu. / The researches carried out in the present work had the objective of evaluating the emission of methane by lambs fed on different tropical pastures: Panicum maximum cv. IZ-5 (Aruana grass) and Cajanus cajan cv. dwarf (pigeon pea), and their relationships with the chemical composition of these pastures. The works were conducted at the Experimental Agronomic Station of UFRGS, between January and April 2016, Chapter II; and from February to April 2015, Chapter III. The experimental design was of randomized complete blocks with three replicates. The blocking was carried out with the objective of eliminating variations of slope of the terrain (flat area, sloping at the top and sloping slope). Chapter II reports the results of methane emission by grazing lambs in the following treatments: 1) ARU - only aruana grass; 2) FG - only Guandu beans; 3) AFG - half picket with aruana grass, and the other half with Guandu beans. For methane evaluation, the SF6 marker technique was used. In the experiment of chapter II, a subdivided plot was used, the subplot being two test animals that received polyethylene glycol (PEG) to chelate the tannin present in the pigeon pea, and two that received water as control. Emissions of methane by dry matter intake (EMICONMSDIA) did not show any difference between treatments, even considering the dosages with polyethylene glycol (PEG) or water (P = 0.9235) FG treatment (P = 0.036) presented higher levels of condensed tannins than the other treatments. Despite differences in their chemical characteristics, the methane emission of lambs is similar between tropical pastures of Aruana grass (Panicum maximum cv. IZ-5), Guandu beans (Cajanus cajan cv. Dwarf), and when these forages are offered at will , in two lanes in the picket. The condensed tannins present in the forage pigeon pea, under the experimental conditions of this work, did not demonstrate the potential to contribute in the reduction of the methane emission by lambs. In Chapter III, treatments, animal management and experimental design were similar to Chapter II. The relationships between the chemical composition of pastures of nutritional influence showed to be quite variable in the methane emission response. The results showed that there is no direct relationship between the biochemical characteristics of the food and the emission of methane. This dissociation between the methane emission and the chemical composition of the pasture was verified both when the emission per animal (EMI) was related and when it was related to the emission per kilogram of ingested dry matter (EMICONMSDIA). It is concluded that it is not possible to relate the emission of methane with the chemical characteristics of perennial tropical forage plants Panicum maximum cv. IZ-5, and Cajanus cajan cv. Dwarf.

De nombreux dispositifs médicaux implantables sont utilisés chaque jour. Le contrôle de l'interface du dispositif avec les tissus vivants environnants doit encore être amélioré. De nombreux dispositifs médicaux implantés dans le corps sont le siège d’une ou plusieurs complications graves, telles que l'infection ou la thrombose. C’est notamment le cas des cathéters intraveineux. Dans ce contexte, nous avons cherché à développer une stratégie permettant de réduire les complications associées à leur utilisation, via l’immobilisation covalente de polymères sur les matériaux utilisés en implantation (polyuréthane). La réactivité des uréthanes a d’abord été étudiée, permettant d’identifier la réaction de transcarbamoylation comme outil efficace de modification des uréthanes et polyuréthanes en conditions douces. La réaction entre des poly(éthylène glycol) et la surface de polyuréthane, catalysée par des bases, a permis de rendre les surfaces de PU hydrophiles. Les conditions de modification ont été optimisées. Les surfaces ont été analysées: angle de contact, spectrométrie infrarouge, XPS et TOF-SIMS. Les surfaces modifiées ont montrées d’excellentes propriétés antiadhésives avec une diminution significative de l’adsorption protéique, de l’adhésion de cellules, de plaquettes et de bactéries. Les propriétés des surfaces modifiées ont été évaluées et comparées à d’autres systèmes. Cette stratégie est prometteuse pour la modification en une étape de surfaces de polyuréthane. Les tests in vitro montrent le potentiel de cette modification de surface pour obtenir un polyuréthane ayant une biocompatibilité accrue. / Many implantable medical devices (stents, catheters, cardiac valves…) are used everyday in many domains. The control of the interface between the medical device and the surrounding tissue is still to be improved. Many implanted devices are facing serious complications following implantation such as infections or thrombosis. These problematics are especially present for intravenous catheters used to administrate drugs. In this context, we investigated a way to strongly limit the problematics associated with their implantation, by covalently binding polymers at the surface, to reduce protein adsorption and cell adhesion on the materials used in implantation (polyurethane). The reactivity of urethanes was first studied, it allowed identifying the transcarbamoylation reaction as an efficient tool to modify urethanes and polyurethanes in soft reaction conditions. The reaction of poly (ethylene glycol) and the polyurethane surface, catalyzed by bases, allowed us to get hydrophilic polyurethane surfaces. Modification conditions were optimized to obtain a good covering of the surface with PEG. Surfaces were analyzed: contact angle, profilometry, infrared spectroscopy, XPS and TOF-SIMS. Modified surfaces showed excellent antiadhesive properties with a strong reduction of protein adsorption, cell and bacterial adhesion. The properties of modified surfaces were evaluated and compared to other systems. This strategy of modification is promising to allow one step modification of polyurethane surfaces. In vitro tests show the potential of this surface modification technique to obtain a polyurethane with enhance biocompatibility.

UV-curing is one of the most commonly used methods for producing hydrogels for soft and hard tissue scaffolds. Spontaneous curing is an alternative method which possesses some advantages in comparison to the conventional UV-curing methods; for example, in situ crosslinking and excluding initiators. The main objective of this study was to investigate promising materials for producing UV and spontaneously cured hydrogels, and subsequently to perform a comparison between the produced hydrogels with regard to their different mechanical and physical properties.Seventeen different hydrogels including five UV-cured and twelve spontaneously cured hydrogels were produced by applying thiol-ene chemistry and by varying precursor materials. Hydrogel systems including di- and tetra- functional PEGs of different lengths (2 kDa and 6 kDa) and two different thiol-crosslinkers (ETTMP 1300 Da and DTT) were subsequently characterized and evaluated. The evaluation tests applied in this study were Raman spectroscopy, weight and volumetric swelling test, leaching test, tensile test, and rheology test. Between all the systems, tetra-acrylated PEG (6 kDa) BisMPA was found to be the most promising system. The pH level of the applied solvent (PBS) for spontaneously cured hydrogels was varied from the physiologically relevant level of 7.4 to 7.0 and 7.8 in order to investigate the dependency of physical and mechanical properties of the hydrogels to this parameter.Spontaneous curing of tetra-acrylated PEG (6 kDa) BisMPA with ETTMP 1300 Da as the thiol-crosslinker, was accomplished within 3½ min in PBS with a pH level of 7.4; and it came out to be the fastest spontaneously cured system between all the tested hydrogels. Increasing the PBS pH level resulted in a faster curing process (accomplished in 1½ min). Spontaneously cured hydrogels generally showed decreased mechanical properties, but improved swelling behavior compared to UV-cured hydrogels. Nevertheless, the discussed system still possessed 50% of the elastic modulus in the tensile test in comparison to the UV-cured state; and showed the highest elastic modulus in comparison to other spontaneously cured systems. The storage modulus of the mentioned hydrogel in the spontaneously cured state was very close to the same parameter in the UV-cured hydrogel based on the same precursors. It also possessed the highest storage modulus between all the spontaneously cured hydrogels. Although the obtained swelling properties of this system were not the highest between all the tested hydrogels, these parameters were still in an acceptable range as for a hydrogel proposed for tissue scaffold application (swelling ratio: 9.72, water content: 89.71%, volumetric swelling ratio: 9.05). Furthermore, the system had the lowest weight loss ratio between all the acrylate-based hydrogels (including both UV and spontaneously cured systems), which along with the Raman spectroscopy results shows the high crosslinking efficiency of the system.

Adenosine triphosphate (ATP) is the major carrier of chemical energy in cells. The diffusion of ATP in hydrogels, which have a structural resemblance to the natural extracellular matrix, is therefore of great importance to understand many biological processes. In continuation of our recent studies of ATP diffusion in poly(ethylene glycol) diacrylate (PEG-DA) hydrogels by pulsed field gradient nuclear magnetic resonance (PFG-NMR), we present precise diffusion measurements of ATP in aqueous solutions of PEG-DA polymers, which are not cross-linked to a three-dimensional network. The dependence of the ATP diffusion on the polymer volume fraction in the hydrogels, φ, was found to be consistent with the predictions of a modified obstruction model or the free volume theory in combination with the sieving behavior of the polymer chains. The present measurements of ATP diffusion in aqueous solutions of the polymers revealed that the diffusion coefficient is determined by φ only, regardless of whether the polymers are cross-linked or not. These results seem to be inconsistent with the free volume model, according to which voids are formed by a statistical redistribution of surrounding molecules, which is expected to occur more frequently in the case of not cross-linked polymers. The present results indicate that ATP diffusion takes place only in the aqueous regions of the systems, with the volume fraction of the polymers, including a solvating water layer, being blocked for the ATP molecules. The solvating water layer increases the effective volume of the polymers by 66%. This modified obstruction model is most appropriate to correctly describe the ATP diffusion in PEG-DA hydrogels.

No description available.