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The current study and discuss the long-term properties of biomedical polymers in vitro and invivo and presents means to design and manufacture antimicrobial composites. Antimicrobialcomposites with reduced tendency for biofilm formation should lead to lower risk for medicaldevice associated infection.The first part analyse in vivo degradation of invasive silicone rubber tracheostomy tubes andpresents degradation mechanism, degradation products and the estimated lifetime of thematerials.. It was found that silicone tubes undergo hydrolysis during the long-term exposurein vivo, which in turn results in decreased stability of the polymer due to surface alterationsand the formation of low molecular weight compounds.The second part of the study presents the manufacturing of composites with single, binary andternary ion-exchanged zeolites as an antimicrobial agent. The ion distribution and release ofthe zeolites and the antimicrobial efficiency of the different systems showed that single silverion-exchanged zeolite was superior to the other samples. Antimicrobial composites wereprepared by mixing the above-mentioned zeolites and pure zeolite (without any ion) withdifferent fractions into polyether (TPU), polyether (PEU) polyurethane and silicone rubber.The antimicrobial efficiency of binary and ternary ion-exchanged samples was similar whichis thought to be due to the ion distribution in the crystal structure.The changes in the mechanical and surface properties of the composites due to the zeolitecontent demonstrated that the increasing zeolite content reduced the mechanical propertieswhile the surface properties did not change significantly. The antimicrobial tests showed thatthe silver-containing composite was the most efficient among all the other samples. Thebinary and ternary ion-exchanged composites expressed similar antimicrobial efficiency as itwas seen previously for the different zeolite systems. Biocompatibility was studied byexposure to artificial body fluids to simulate the degradation of the composites in the humanbody. Significant changes were observed in the morphology, the surface properties and the chemical structure. / QC 20110511

Orientador: Eliana Aparecida de Rezende Duek / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T07:55:59Z (GMT). No. of bitstreams: 1 Esposito_AndreaRodrigues_M.pdf: 4037379 bytes, checksum: 0972d6543df2aa3ece0f74e93c30dfc4 (MD5) Previous issue date: 2010 / Resumo: A engenharia tecidual utilizando células fibrocartilaginosas e arcabouços poliméricos representa uma alternativa para o tratamento de lesões do menisco. Neste estudo, arcabouços de PLDLA/PCL-T (90/10) contendo sacarose (50% m/v) foram obtidos por evaporação de solvente. Fibrocondrócitos provenientes do menisco de coelhos foram isolados e semeados diretamente sobre os arcabouços. Estudos in vitro demonstraram que o arcabouço não apresentou citotoxicidade e permitiu a adesão e o crescimento de fibrocondrócitos, bem como manutenção da síntese de matriz extracelular colágena nos tempos de 7, 14, 21 e 28 dias de cultivo. Os implantes de PLDLA/PCL-T foram realizados no menisco medial do joelho de 20 coelhos, após a meniscectomia total, obtendo-se três tratamentos: arcabouço com pré-cultivo celular por 21 dias, arcabouço sem células e controle. Após 12 e 24 semanas, as análises histológicas dos "neomeniscos" apresentaram a formação de fibrocartilagem nos implantes com os arcabouços. A presença de tecido fibrocartilaginoso maduro com fibras colágenas organizada foi predominantemente observada nos implantes realizados com os arcabouços pré-cultivados em comparação com os implantes sem células após 24 semanas. Este estudo demonstrou que a regeneração de uma importante estrutura fibrocartilaginosa pode ser alcançada utilizando arcabouço polimérico biorreabsorvível e células alógenas dentro dos princípios da engenharia de tecidos / Abstract: Tissue engineering of meniscus using fibrochondrocyte-like cells and bioreabsorbable polymer scaffolds could be an alternative option to treat meniscus injury. In this study PLDLA/PCL-T (90/10) scaffolds containing sucrose (50% m/v) were obtained by casting. Allogeneic meniscal cells were isolated from rabbit meniscus and directly seeded onto the scaffolds. In vitro studies showed that scaffolds did not present cytotoxicity and allowed fibrochondrocytes adhesion and ingrowth, as well as collagen extracellular matrix synthesis at 7, 14, 21 and 28 days of culture. The PLDLA/PCL-T implants were performed in the medial meniscus of 20 rabbit knee after total meniscectomy, obtained three treatments: pre-seeded 21 days scaffold, unseeded scaffold and control. Histology analysis of "neomenisci" sections at 12 and 24 weeks revealed the presence of fibrocartilage in the polymer implants. The presence of mature fibrocartilaginous tissue with organized collagen fibers was predominantly observed in the pre-cultured implants compared to unseeded implants after 24 weeks. This study demonstrates that regeneration of an important fibrocartilaginous structure can be achieved using a bioreabsorbable polymer scaffold and allogeneic cells-based tissue engineering approaches / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica