Orientadores: Paulo Pinto Joazeiro, Eliana Aparecida de Rezende Duek / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-15T19:20:15Z (GMT). No. of bitstreams: 1 Lucchesi_Carolina_D.pdf: 5696358 bytes, checksum: 89bc8546c0a1d6b5a11d7260168dd236 (MD5) Previous issue date: 2010 / Resumo: Os polímeros biorreabsorvíveis, tais como, PHB, PCL e PLGA, têm sido estudados como dispositivo para engenharia de tecidos por serem biocompatíveis, suportarem o crescimento e diferenciação celular e os produtos de sua degradação serem atóxicos. No entanto, a escolha do biomaterial depende das necessidades exigidas para uma determinada aplicação. Os suportes para engenharia de tecidos devem se basear na construção de réplicas biológicas in vitro, como que o biomaterial se tornasse parte integrada para transplante in vivo para a recuperação de perdas ou mau funcionamento de tecidos ou órgãos, devendo subseqüentemente, atuar sem agredir o restante do organismo, isto é, sem o risco de rejeição ou complicação. Muitas estratégias têm sido desenvolvidas com o intuito de substituir tecidos ou órgãos danificados, incluindo a aplicação de suportes tridimensionais (3D), os quais devem possuir características estruturais e mecânicas para guiar a proliferação e espalhamento de células in vitro e in vivo. Os suportes, feitos de materiais sintéticos ou naturais, servem como substitutos para a matriz extracelular (MEC) nativa. Ênfase especial é dada as técnicas com controle computadorizado, como a fabricação sólida com forma livre (SFF), conhecida como prototipagem rápida (RP), a qual permite preparar suportes 3D com geometrias complexas, tanto externamente como internamente, além de ser uma técnica rápida e de baixo custo. Além disso, grande parte dos polímeros possuem superfície hidrofóbica, característica inadequada para a maior parte dos diferentes tipos celulares, o que dificulta aplicação na engenharia de tecidos. Uma alternativa a este problema é o tratamento da superfície por plasma. Este tratamento induz modificação restrita ao topo da superfície, conferindo carater hidrofílico à superfície, dependendo do gás utilizado. Neste estudo, arcabouços de polímeros biorreabsorvíveis PCL, PLGA e PHB foram preparados por diferentes técnicas, casting e sinterização seletiva a laser, avaliando-se o comportamento de células osteoblásticas diferenciadas sobre os biomateriais poliméricos tridimensionais. Inicialmente o trabalho foi desenvolvido com os polímeros PCL e PLGA preparando-se blendas poliméricas, as quais demonstraram melhorar as características gerais dos polímeros, quando utilizados como dispositivos para tecido ósseo, como as propriedades mecânicas. Com o intuito de aprimorar o design tridimensional do material, optou-se pela realização da técnica de sinterização seletiva a laser. No entanto, a técnica exige uma grande quantidade de material e devido ao alto do custo do PCL e PLGA, este foi substituído pelo polímero PHB, o qual é produzido pela indústria nacional Biocycle possuindo um baixo custo e ainda ser biocompatível. Os dados são apresentados em capítulos independentes. Arcabouços porosos de PCL, PLGA e suas blendas foram preparados pela técnica de evaporação do solvente, onde sais de citrato de sódio com granulometria de 180-250 µm, foram adicionados a solução para a promoção dos poros, sendo posteriormente lavados do arcabouço. Células osteoblásticas provenientes de calota craniana de ratos Wistar foram semeadas sobre os arcabouços, sendo avaliado o comportamento de citoxicidade do material e o comportamento de adesão e morfologia celular através de ensaios bioquímicos e MEV. Os arcabouços de PHB foram obtidos por uma das técnicas de RP, a sinterização seletiva a laser (SSL), sendo sua superfície modificada por plasma pelos gases oxigênio e nitrogênio. Células osteoblásticas provenientes de calota craniana de coelhos foram semeadas sobre os arcabouços realizando-se o estudo in vitro, através de análises bioquímicas pela técnica do MTT, para viabilidade e adesão celular, quantificação de colágeno por Sírius Red e Microscopia Eletrônica de Varredura (MEV). Para o estudo in vivo, após o cultivo celular sobre os arcabouços, defeitos ósseos foram provocados em coelhos e os arcabouços contendo as células foram então implantados, avaliando-se a interação PHB/osteoblasto/tecido, através da análise histológica. Todos os arcabouços estudados, PCL, PLGA e suas blendas, assim como o PHB, não apresentaram índices de citotoxicidade, permitiram às células a capacidade de adesão, proliferação e síntese de matriz, mantendo seu fenótipo osteoblástico. As amostras de PHB tratadas por plasma de Nitrogênio mostrou melhorar a capacidade de adesão celular. Os arcabouços de PHB contendo células mostraram-se os mais adequados para o preenchimento de defeitos ósseos, melhorando o processo de regeneração apresentando uma boa osteointegração. A sinterização seletiva a laser apresentou-se uma excelente técnica para a obtenção de PHB 3D para a Engenharia de Tecidos. / Abstract: The bioresorbable polymers as, PHB, PCL and PLGA have been studied as device for Tissue Engineering for their biocompatibility and to support the cell growth and differentiation and their degradation products are nontoxics. However, the choice of the biomaterial depends on the needs demanded for a certain application. The scaffolds for tissue engineering have to be designed to mimetize the biological conditions in vitro to became part integrated for transplant for the recovery of tissue or organs lost or without function, and subsequently, to work in a cordial way with the remaining of the organism without the rejection risk or complication. A lot of strategies have been developed with to substitute damaged tissues or organs, and it has been used the application of three-dimensional supports (3D), which should possess structural and mechanical applications to guide the cells proliferation and spread in vitro and in vivo. The scaffolds, made from synthetic or natural materials, serve as substitutes for the extracellular matrix (ECM) native. Special emphasis is given the techniques with computerized control, as the free solid form (SFF), known as rapid prototyping (RP), which allows to prepare three-dimensional supports with complex geometries, so much externally as internally, besides to be a fast technique with low cost. Besides, great part of the polymers possess hydrophobic surface, inadequate characteristic for most of the different cell types, which is not desirable for tissue engineering applications. An alternative to this problem is the surface treatment by plasma. Plasma treatment induces restricted modification to the top of the surface, improving the surface hydrophilicity, depending on the gas used. In this study, scaffolds of bioresorbable polymer PCL, PLGA e PHB were prepared by different techniques, casting and selective laser sintering, being evaluated the osteoblast cells behavior on the 3D polymer scaffolds. Previously we developed the studies preparing the polymeric blends with PCL and PLGA, which demonstrated improve the general characteristic of the material, as the mechanical properties, as devices for bone tissue. With the intention to improve the design of the scaffolds, we chose for the selective laser sintering technique. However, the technique demands a great amount of material and due to the high cost of PCL and PLGA, those weres substituted by PHB polymer, which is produced by Brazilian industry Biocycle with low cost and still to be biocompatible. For those reasons the data are presented in independent chapters. PCL, PLGA porous scaffolds and their blends were prepared those scaffolds by casting solvent, and sodium citrate with 180-250 µm were added to the solution for porous formation when the salt was washed later of the scaffolds. Osteoblast cells from rat Wistar calvaria were seemed on the scaffolds, being evaluated the behavior of cell adhesion and viability behavior, cell morphology through biochemical assays, and scanning electron microscopy. Three-dimensional PHB scaffolds were obtained by selective sintering laser (SSL), with the surface modified by nitrogen and oxygen plasma. Osteoblast cells obtained from rabbit calvaria were seemed on the scaffolds to the in vitro studies, through biochemical analyses by MTT test for cell viability and cell adhesion, collagen quantification of by Sirius Red colorimetric assay and scanning electron microscopy (SEM). For the in vivo studies, bone defects were provoked in rabbits and they were filling out with 3D PHB with osteoblast cells culture prior implant. We evaluated the PHB/osteoblast/tissue, interaction through the histological analysis. All the scaffolds studied PCL, PLGA and their blends, as well as the PHB did not showed cytotoxicity effects, allowed cells adhere, proliferated, and matrix synthesized, maintaining their osteoblastic phenotype. The PHB samples treated by nitrogen plasma have been showed to improve the cell adhesion. The PHB scaffolds with cell seeded previously demonstrated to be more suitable for filling out bone defects, improving the regeneration process showing a good osteointegration. The selective laser sintering was excellent technique to obtain PHB scaffolds for Tissue Engineering. / Doutorado / Biologia Celular / Doutor em Biologia Celular e Estrutural

L´objectif du travail présenté dans ce manuscrit consiste à conserver les bonnes propriétés mécaniques du poly(butadiène) dihydroxytéléchélique (PBHT) tout en améliorant sa stabilité. Un des principaux verrous techniques de cette approche réside dans le fait que les doubles liaisons responsables la flexibilité du matériau sont également la cause de son vieillissement par oxydation. Les solutions proposées reposent sur l´utilisation de la métathèse comme outils de synthèse de polymères insaturés. Deux grandes voix de synthèse ont été étudiées : la polymérisation par ouverture de cycle via métathèse (ROMP) ainsi que la dépolymerisation fonctionnalisante (ADMET). Ces deux approches bien que prometteuses n’ont pas permis de sortir de la relation ciseau existante entre flexibilité et stabilité. Finalement, une solution basée sur le mélange entre deux polymères dihydroxytéléchéliques de basse température de transition vitreuse – poly(butadiene) et poly(isobutylene) a permis de répondre dans une certaine mesure aux cahier des charges. En parallèle a ces parties synthèses, une étude physique des relations structure-propriétés visant à améliorer la stabilité des oligomères a été apporté par mesure rhéologique du temps critique de réticulation. / The work reported in the following document is aiming at maintaining the good mechanical properties of diHydroxyTelechelic PolyButadiene HTPB while improving its stability. The major challenge of this approach is that the unsaturations responsible for the outstanding flexibility of the material are also rather sensitive to oxidation. The solutions presented in this study are based on the use of metathesis reactions as a tool for the design of new difunctional unsaturated oligomers. Two functionalization techniques have been investigated, on the one hand, the Ring Opening Methathesis Polymerisation (ROMP) and, on the other hand, the depolymerisation via Acyclic Diene METathesis (ADMET). Although promising, the latters proved to fall into the vicious circle consisting in simultaneously increasing the stability while losing the flexibility. Finally, a blending concept based on the mixture of two dihydroxytelechelic polymers, namely, poly(isobutylene) and poly(butadiene), could enable us to achieve our initial goal. In addition to the chapters focusing on polymer chemistry and synthesis, a physical study of the parameters influencing the aging of unsaturated oligomers have been set-up and the properties relationship using measurements of the critical time.

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Certaines applications (notamment dans l'aéronautique) demandent des polymères thermostables semi-cristallins avec des résistances et des températures de fonctionnement de plus en plus élevées (Tg supérieures à 170°C) tout en conservant de bonnes propriétés de mise en œuvre (Tf ne dépassant pas 350°C) aptes aux procédés industriels. Ce projet de thèse porte sur la synthèse et la caractérisation de nouveaux polymères hautes performances de type poly(aryl éther cétone amide)s à partir d'un monomère de type EKKE aux extrémités acide carboxylique. Ainsi, trois voies de synthèse des amides par condensation ont été étudiées : entre les acides carboxyliques et les isocyanates, entre les chlorures d'acyle et les amines, et entre les acides carboxyliques et les amines par phosphorylation. La comparaison des propriétés thermiques et leurs corrélations avec les structures chimiques des poly(aryl éther cétone amide)s aromatiques et semi-aromatiques obtenus sont particulièrement détaillées. / Some demanding applications (especially in aerospace) require more and more semi-crystalline thermostable polymers with high temperature resistance and durability (Tg above 170 °C) while maintaining good processing properties (Tm not exceeding 350°C) suitable for industrial manufacturing.This work deals with the synthesis and characterization of new high performance poly(aryl ether ketone amide)s polymers from an EKKE monomer with carboxylic acid extremities. Thus, three amide condensation synthetic routes were studied: between carboxylic acids and isocyanates, between acyl chlorides and amines, and between carboxylic acids and amines by phosphorylation. The thermal properties and their correlation with the chemical structures of the obtained aromatic and semi-aromatic poly(aryl ether ketone amide)s are compared and especially detailed.

End-functional poly(ether amic acid)s and poly(siloxane imide) multiblock copolymers, comprised of 2,2'-Bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) / meta-phenylene diamine (MPDA) and hexafluoroisopropylidene-2-bis(phthalic acid anhydride) (6FDA) / meta-phenylene diamine (MPDA) polyimide segments, have been prepared and characterized to explore possibilities for controlling interface properties. Incorporation of polydimethylsiloxane (PDMS) components into polyimide backbone structures can yield advantageous properties such as low energy surfaces and low stress interfaces. End-functional BPDA/MPDA poly(amic acid) salts and poly(siloxane amic acid) salts were prepared in methanolic or aqueous tripropylamine solutions. The polymeric salts formed stable water solutions (or dispersions) and imidized in less than 10 minutes at 260°C. The water solubility and rapid imidization times are ideal for on-line processing. Thus, these materials can be used as sizing and interface toughening agents for fiber reinforced composite manufacturing. Epoxy-polyimide networks prepared from the amine functionalized polyimide with DER 331 epoxy resin and diamino diphenylsulfone showed microphase separation (100-300 nm inclusions) by transmission electron microscopy. Slight toughening of the cured epoxy with 9 weight % imide was observed with the imide as the included phase. Epoxy bilayer films of polyimide (amine end-functional and commercial Ultem™) and poly(siloxane imide) multiblock copolymers were prepared to evaluate the polymer-matrix interphase region. Atomic force microscopy (AFM) analysis of the bilayer films showed diffusion at the interphase for the bilayers prepared with the polyimides and the BPADA/MPDA block copolymers containing polyimide continuous phases. Poly(siloxane imide) multiblock copolymers comprised of 6FDA/MPDA polyimide structures are ideal candidates for controlling interfacial properties between silicon substrates layered with thin films for microelectronic applications. These high Tg materials offer an approach for obtaining reduced moisture absorption and low stress interfaces. Evaluation of the refractive indices of the block copolymer films showed a decrease with increasing siloxane content thus suggesting the possibility of lower dielectric constants. The polymer-metal interfacial properties were investigated for films cast on titanium and tantalum substrates. The results suggested a correlation between the surface hydroxyl concentration of the metal oxide layer with the interfacial properties of the cast poly(siloxane imide) block copolymer films. The surface hydroxyls were thought to hydrogen bond with the PDMS component of the block copolymer. Since the titanium substrate has a higher surface hydroxyl concentration than the tantalum, higher silicon concentrations were observed. The melt imidized end-functional polyimides and poly(siloxane imide) block copolymers produced thermally stable materials with 5% weight loss temperatures well above 400°C. However, the block copolymers showed slightly lower 5% weight loss temperatures as a function of siloxane content with a significant increase in char formation. Correlation of the upper glass transition temperatures with the imide segment length was consistent with findings noted for other phase separated randomly segmented block copolymers. Incorporating PDMS into the polyimide backbone structure has an effect on the bulk and surface properties. The bulk properties of the poly(siloxane imide) block copolymers were characterized using TEM. The morphologies were consistent with classical block copolymers. Surface properties of the block copolymer films as a function of PDMS content were investigated using angular dependent X-ray photoelectron spectroscopy at take-off angles of 15, 30, and 45°. Surface enrichment of PDMS content over that of the bulk was observed at all three sampling depths. Further evidence of this siloxane enrichment in the surface was demonstrated with water contact angle analyses. With as little as 5 weight % PDMS (<Mn> = 5000 g/mol) in the block copolymer there was over a 25% increase in the water contact angle over the polyimide control. The surface topography was influenced by the degree of phase separation and was characterized using AFM. The roughness factor was used to represent the data. It was found that the surface roughness increased with increasing PDMS content. / Ph. D.

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Electrooxidation has been used to deposit thin film polyaniline as well as its derivative - thin film poly (ortho-phenylenediamine) (POPD) and poly (meta-phenylenediamine) (PMPD) on carbon electrodes, which are subsequently used to monitor the environmental heavy metal ions (Hg2+, Pb2+ ,Cd2+) through a rather unusual "blocking" of anodic stripping for these metals. Using Hg2+ as a model, its cyclic voltammogram for a modified glassy carbon electrode with the resultant polymer shows an enhanced cathodic peak that increases linearly with the analyte ion concentration. POPD also exhibits unique selective detection for organic species. Acetaminophen and uric acid can be preferentially detected over ascorbic acid from a mixture of these three compounds. In addition, the effect of carbon nanotubes incorporated in polyaniline (PAN) film is observed to have enhanced electrochemical catalytic activities on the remedy of environmental dichromate.

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