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Abstract(s)
Este trabalho foi desenvolvido no âmbito do mestrado em Tecnologia Biomédica e é essencialmente de natureza experimental, tendo como principal objetivo a produção de micropartículas deformáveis em polidimetilsiloxano (PDMS), capazes de simular o comportamento mecânico dos glóbulos vermelhos (GVs). A técnica utilizada para a produção das partículas foi a focagem de fluxo na qual é formado um jato de PDMS dentro de um capilar de vidro, quebrando-se em microgotas de PDMS as quais são curadas para se obter micropartículas sólidas. Esta técnica já foi usada anteriormente por Muñoz-Sánchez, et al. 2016 demonstrando a sua viabilidade na produção de partículas com dimensões abaixo de 10 μm. Neste trabalho utilizou-se a mesma técnica e efetuou-se um estudo intensivo sobre a redução do tamanho das microgotas produzidas aquando da passagem do estado líquido para sólido – coeficiente de redução de tamanho. O estudo foi efetuado para vários rácios de PDMS. Foram, ainda, introduzidos corantes para atribuir cor às micropartículas produzidas e facilitar a sua visualização no sistema de microscopia, efetuando-se também o estudo do coeficiente de redução de tamanho para as partículas produzidas com PDMS corado (corante vermelho) e PDMS cinzento.
Por fim, e não menos importante, as micropartículas produzidas, foram suspendidas em Dextrano 40 (Dx 40) para se poder analisar a sua capacidade de deformação aquando da passagem por um microcanal com contração hiperbólica de dimensão 12 μm. Os resultados do índice de deformação (ID) foram comparados com o ID de GVs a escoarem no mesmo microcanal. Foi ainda obtida a curva de viscosidade das suspensões das micropartículas a 22º C e de igual forma comparadas com a curva de viscosidade obtida para 5 % de GVs suspendidos também em Dx 40.
Este trabalho possibilitou, pela primeira vez, tirar conclusões sobre o coeficiente de redução das partículas de PDMS após a cura, ajudando assim, a entender melhor o processo de fabricação. Foi ainda possível estudar as propriedades de deformação e reológicas das suspensões das micropartículas produzidas. Com os resultados obtidos neste trabalho é possível concluir que as micropartículas produzidas têm uma grande
potencialidade para desenvolver fluidos análogos do sangue, pois obtivemos valores de ID próximos dos GVs e curvas de viscosidade similares às suspensões de GVs em Dx 40.
This work was developed under the master's degree in Biomedical Technology and is essentially an experimental work, having as main objective the production of polydimethylsiloxane (PDMS) deformable microparticles able to mimic the mechanical behavior of human red blood cells (RBCs). The technique used for the production of the particles was the flow focusing technique in which a PDMS jet is formed inside a glass capillary, breaking into PDMS microdroplets which are cured to obtain solid microparticles. This technique was previously used by Muñoz-Sánchez, et al. 2016 ant it was demonstrated ability to produce particles with dimensions below 10 μm. In this work the same technique was used and a detailed study was carried out regarding the reduction of the size of the microdroplets produced during the transition from liquid to solid state – curing shrinkage coefficient. The study was carried out for several PDMS ratios. Dyes were also applied to introduce color into the microparticles and to improve their visualization in the microscopic system. In addition, the study of the curing shrinkage coefficient for color particles was performed. Last, but not least, the microparticles produced and dried were suspended in Dextran 40 (Dx 40) in order to analyze their deformability when passing through a microchannel with a hyperbolic contraction. The results of the particles deformability were compared to the deformation index of the RBCs flowing in the same microchannel. The viscosity curve of the microparticles suspensions was also obtained at 22 ° C and compared with viscosity curve obtained for 5% of RBCs also suspended in Dx 40. This work made possible, for the first time, to obtain results about the curing shrinkage coefficient of the PDMS particles, helping to improve our understanding regarding the production of PDMS microparticles. It was also possible to study the deformability and rheological properties of the microparticles suspensions. Hence, with the obtained results it was possible to conclude that the produced microparticles have the potential to improve the existent blood analogue fluids, since the obtained values of deformation index of the particles were in close agreement with the RBCs deformability and the viscosity curves were similar to the suspensions of RBCs in Dx 40.
This work was developed under the master's degree in Biomedical Technology and is essentially an experimental work, having as main objective the production of polydimethylsiloxane (PDMS) deformable microparticles able to mimic the mechanical behavior of human red blood cells (RBCs). The technique used for the production of the particles was the flow focusing technique in which a PDMS jet is formed inside a glass capillary, breaking into PDMS microdroplets which are cured to obtain solid microparticles. This technique was previously used by Muñoz-Sánchez, et al. 2016 ant it was demonstrated ability to produce particles with dimensions below 10 μm. In this work the same technique was used and a detailed study was carried out regarding the reduction of the size of the microdroplets produced during the transition from liquid to solid state – curing shrinkage coefficient. The study was carried out for several PDMS ratios. Dyes were also applied to introduce color into the microparticles and to improve their visualization in the microscopic system. In addition, the study of the curing shrinkage coefficient for color particles was performed. Last, but not least, the microparticles produced and dried were suspended in Dextran 40 (Dx 40) in order to analyze their deformability when passing through a microchannel with a hyperbolic contraction. The results of the particles deformability were compared to the deformation index of the RBCs flowing in the same microchannel. The viscosity curve of the microparticles suspensions was also obtained at 22 ° C and compared with viscosity curve obtained for 5% of RBCs also suspended in Dx 40. This work made possible, for the first time, to obtain results about the curing shrinkage coefficient of the PDMS particles, helping to improve our understanding regarding the production of PDMS microparticles. It was also possible to study the deformability and rheological properties of the microparticles suspensions. Hence, with the obtained results it was possible to conclude that the produced microparticles have the potential to improve the existent blood analogue fluids, since the obtained values of deformation index of the particles were in close agreement with the RBCs deformability and the viscosity curves were similar to the suspensions of RBCs in Dx 40.
Description
Mestrado em cooperação com a Universidad de Extremadura
Keywords
Técnica de focagem de fluxo Produção de micropartículas Coeficiente de redução de tamanho Índice de deformação Escoamento em microcanais Viscosidade