Diss. (sammanfattning) Uppsala : Uppsala universitet, 2008. / Härtill 5 uppsatser.

München, Techn. Universiẗat, Diss., 2004.

The purpose of this master’s thesis was to, by the use of nanotechnology, improve material properties of the biomedical polymer Optim™, used as the insulation of pacemaker leads. Improved material properties are required to reduce the extent of fibrous encapsulation of the leads. Today, laser ablation is used to be able to remove the pacemaker lead because of the fibrous tissue, which can cause the lead to adhere to vascular structures. Consequently, the laser ablation results in risks of damaging cardiovascular structures. Moreover, improved material properties are needed to reduce the friction at the surface and enhance the wear resistance. Large wearing occurs between the lead and the titanium pacemaker shell as well as lead against lead and the wearing can result in a damaged insulation, which in turn might result in removal of the device. To achieve these improved material properties a hierarchically micro- and nanostructured and superhydrophobic surface was fabricated and to enhance the wear resistance, nanocomposites with 1 wt % and 5 wt % added hydroxyapatite nanoparticles were fabricated. The surface structures were fabricated via hot embossing and plasma treatment and were characterised with atomic force microscopy, environment scanning electron microscopy and with contact angle measurements. To evaluate the biological response to the surfaces, adsorption of radioisotope labelled human serum albumin proteins and adhesion of the human fibroblast cell line MRC-5 were studied. The results show that a superhydrophobic surface, with contact angle as high as 170.0 ± 0.4 °, can be fabricated via hierarchically micro- and nanostructures on an Optim™ surface. The fabricated surface is more protein resistant and cell resistant compared to a smooth surface. The nanocomposites fabricated, especially the one with 5 wt % nanoparticles added, show an enhanced abrasive wear resistance compared to Optim™ without added nanoparticles. In conclusion, a hierarchically micro- and nanostructured superhydrophobic surface of the pacemaker lead seems promising for reducing the extent of fibrous encapsulation and by fabricating a nanocomposite, the abrasive wear damage of the lead insulation can be reduced.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2005. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 5 uppsatser.

Lic.-avh. (sammanfattning) Luleå : Luleå tekniska univ., 2008. / Härtill 3 uppsatser.

Orientadores: Cecilia Amelia de Carvalho Zavaglia, Eliria Maria de Jesus Agnolon Pallone / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-18T21:45:50Z (GMT). No. of bitstreams: 1 Silva_KatiaLeticiada_M.pdf: 4465525 bytes, checksum: beccaaf7d57aa62f45a93ae73feafa20 (MD5) Previous issue date: 2011 / Resumo: Cerâmicas de alumina de alta densidade e elevada pureza são usadas como biomateriais devido à combinação de excelente resistência à corrosão, boa biocompatibilidade, alta resistência ao desgaste e moderada resistência mecânica. Porém, a sua baixa tenacidade à fratura limita a sua gama de aplicações. Uma possibilidade para melhorar as propriedades destes materiais pode estar no uso de inclusões nanométricas de ZrO2 em matriz de Al2O3. O objetivo deste trabalho foi obter e caracterizar nanocompósitos de matriz cerâmica de alumina com inclusões nanométricas de zircônia, variando a quantidade, 5, 10, 15, 30 em volume de zircônia na alumina, visando melhorias nas propriedades mecânicas e de desgaste deste material e o uso do mesmo como biomaterial. Para isso, partículas nanométricas comerciais de ZrO2 foram adicionadas em matriz de alumina em diferentes proporções, utilizando moinho de bolas. As amostras de alumina pura e dos nanocompósitos de alumina-zircônia foram caracterizadas física, microestrutural e mecanicamente. Os resultados deste trabalho mostraram a eficiência do processo utilizado, obtendo uma boa dispersão das partículas de zircônia na matriz de alumina. A inclusão de até 15% de zircônia nanométrica na matriz de alumina promoveu um acréscimo nos valores de compressão diametral. Em relação aos valores de tenacidade à fratura, com o aumento da porcentagem das inclusões conseguiu-se melhores resultados / Abstract: Alumina ceramic of high density and high purity are used as biomaterials due to the combination of excellent corrosion resistance, good biocompatibility, high wear resistance and moderate strength. However, their low fracture toughness limits its range of applications. One possibility to improve the properties of these materials may be in the use of nanometric inclusions of ZrO2 in Al2O3 matrix. The aim of this study was to characterize and ceramic matrix nanocomposites with alumina inclusions of nanometric zirconia, varying the amount, 5, 10, 15, 30 and 50% by volume of zirconia in alumina, seeking improvements in mechanical properties and wear this and using the same material as a biomaterial. For this, commercial ZrO2 nano-sized particles were added into alumina matrix in different proportions using a ball mill. The samples of pure alumina and alumina-zirconia nanocomposites were characterized physical, microstructural and mechanical. These results showed the efficiency of the process used, obtaining a good dispersion of zirconia particles in alumina matrix. The inclusion of up to 15% of nano-zirconia in alumina matrix caused an increase in the values of diametrical compression. Regarding the values of fracture toughness, with increasing percentage of the inclusions could be better results / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Biomaterials are used in many different areas. Often, after implantation, severe host reactions occur which cause the malfunction or failure of the device. In our study, we wanted to investigate the mechanism of biomaterial-induced fibrosis. We focused on three areas: i) the relationship between inflammation and fibrosis after implantation, ii) the role that the SMAD3 gene plays, and iii) how MRL mice react to biomaterials. After implantation, acute inflammation occurs immediately. In pathological fibrosis, it has traditionally been believed that the inflammation is linked to the downstream fibrosis, though this theory has been challenged recently. In our project, we did not observe a direct relationship between intentionally induced inflammation and biomaterial-induced fibrosis. We did observe the dependency of the host reaction on the type of implanted biomaterial. The SMAD3 gene is tightly linked to the pro-fibrotic cytokine TGF-(beta). The SMAD3 protein mediates the TGF-(beta) pathway intracellularly. It was found in pulmonary fibrosis, SMAD3 knockout (KO) mice had lower production of collagen. In our project, we did not observe a difference in cellular behaviour on the surface of the implanted biomaterial between wild-type (WT) and SMAD3 KO mice. We did observe a difference in the production of TGF-(beta)1. This could be a clue that biomaterial-induced fibrosis has more than one mechanism/pathway that is not dependent on TGF-(beta). In our last project, we studied MRL mice that showed potential in scarless wound healing. We observed a higher production of MMP-2, MMP-9 and TGF-(beta)1. Histologically, however, we did not see a difference in cellular behaviour between MRL and C57BL/6 mice. Our results open up the possibilities of different mechanisms and pathways in biomaterial-induced fibrosis. Future studies of cytokines and specific cells could help us further understand the process of encapsulation of the implanted biomaterials. / Thesis / Master of Applied Science (MASc)

Submitted by Suelen Simões Amaral (suelensimoes@live.com) on 2018-05-16T18:24:52Z No. of bitstreams: 1 Amaral_SS_Dissertacao.pdf: 1299570 bytes, checksum: f6d0db234b66c92f7344ce7348080127 (MD5) / Approved for entry into archive by Silvana Alvarez null (silvana@ict.unesp.br) on 2018-05-16T23:30:55Z (GMT) No. of bitstreams: 1 amaral_ss_me_sjc.pdf: 1299570 bytes, checksum: f6d0db234b66c92f7344ce7348080127 (MD5) / Made available in DSpace on 2018-05-16T23:30:55Z (GMT). No. of bitstreams: 1 amaral_ss_me_sjc.pdf: 1299570 bytes, checksum: f6d0db234b66c92f7344ce7348080127 (MD5) Previous issue date: 2018-05-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo do trabalho foi analisar in vitro o comportamento de osteoblastos MG-63 em contato com membranas reabsorvíveis porosas de poli (ácido lático) (PLA) e policaprolactona (PCL), incorporadas com fibras cerâmicas de silicato de cálcio (CaSiO3), visando aplicação na regeneração óssea guiada. Foram utilizados seis grupos experimentais, a partir da concentração do teor de CaSiO3, PLA P; PLA + 5% CaSiO3; PLA + 10% CaSiO3; PCL P; PCL + 5% CaSiO3; PCL + 10% CaSiO3, e o grupo controle. Foram avaliadas viabilidade celular, genotoxicidade; produção de proteína total, atividade de fosfatase alcalina e formação matriz mineralizada. Bem como, a influência das membranas poliméricas na redução de biofilmes monotípicos de Enterococcus faecalis quando associadas ou não a solução de gluconato de clorexidina a 0,12%. Os dados foram analisados por ANOVA e Tukey (p<0.05%). Os resultados mostraram que nenhum grupo experimental foi citotóxico, mas os grupos PCL P, PLA 5%, PLA P e PCL 10% apresentaram maior viabilidade celular com diferença estatística dos grupos PCL 5% e PLA 10% (p<0.05). No teste de genotoxicidade os grupos experimentais não foram genotóxicos, já que apresentaram números de micronúcleos semelhantes ou menores ao grupo controle (p>0.05). Todos os grupos experimentais apresentaram proteína total e atividade de fosfatase alcalina semelhante estatisticamente ao controle (p>0.05) e permitiram a formação de matriz mineralizada. Com relação à redução de biofilme, os grupos experimentais PCL P e PCL 10% apresentaram maior redução de biofilme para Enterococcus faecalis com diferença estatística (p<0.05) do PCL 5% e do controle. Nos grupos experimentais de PLA, todas as membranas promoveram maior redução de biofilme com diferença estatística (p<0.05) do grupo controle. Entretanto quando os grupos experimentais de PCL, bem como de PLA foram tratados com gluconato de clorexidina, observou-se redução do biofilme em todos os grupos, sem diferença estatística do grupo controle (p>0.05). Concluiu-se que as membranas poliméricas são biomateriais adequados para o uso em regeneração óssea guiada. Da mesma maneira, pareceram contribuir para a osteogênese e redução de biofilme de Enterococcus faecalis. / The objective of this study was to analyze the behavior of MG-63 osteoblasts in contact with poly (lactic acid) (PLA) and polycaprolactone (PCL) porous resorbable membranes, incorporated with calcium silicate ceramic fibers (CaSiO3), aiming application in bone regeneration guided in periapical lesions. Six experimental groups were used, from the concentration of CaSiO3, PLA P; PLA + 5% CaSiO3; PLA + 10% CaSiO3; PCL P; PCL + 5% CaSiO3; PCL + 10% CaSiO3, and the control group. Cell viability, genotoxicity; total protein production, alkaline phosphatase activity and mineralized matrix formation. As well as the influence of polymer membranes on the reduction of monotypic biofilms of Enterococcus faecalis when associated with 0.1% chlorhexidine gluconate solution. Data were analyzed by ANOVA and Tukey (p <0.05%). The results showed that no experimental group was cytotoxic, but the PCL P, PLA 5%, PLA P and PCL 10% groups presented higher cell viability with a statistical difference between PCL 5% and PLA 10% (p <0.05). In the genotoxicity test, the experimental groups were not genotoxic, since they had similar or smaller numbers of micronuclei to the control group (p> 0.05). All experimental groups presented total protein and alkaline phosphatase activity statistically similar to the control (p> 0.05) and allowed the formation of mineralized matrix. Regarding the biofilm reduction, the PCL P and PCL 10% experimental groups showed a higher biofilm reduction for Enterococcus faecalis with a statistical difference (p <0.05) in PCL 5% and control. In the PLA experimental groups, all membranes promoted a higher biofilm reduction with a statistical difference (p <0.05) in the control group. However, when the PCL and PLA groups were treated with chlorhexidine gluconate, biofilm reduction was observed in all groups, with no statistical difference in the control group (p> 0.05). It was concluded that the polymer membranes are biomaterials suitable for use in guided bone regeneration. In the same way, they appeared to contribute to the osteogenesis and biofilm reduction of Enterococcus faecalis.