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5.1 CONCLUSÕES
A Engenharia de tecidos é uma área em crescimento e que nas próximas décadas se tornará uma das maiores áreas em expansão na ciência com vista a diminuir as necessidades de órgãos e tecidos para substituição na saúde e aplicada indiretamente na descoberta e desenvolvimento de curas menos prejudiciais ao ser humano e no conhecimento do ser humano.
A utilização de polímeros permite avanços maiores na construção de scaffolds não só pela sua fácil manipulação, mas também à diversidade.
É importante ter a máxima que a estrutura produzida tem de mimetizar o mais possível o ambiente encontrado no organismo humano e oferecer as mesmas condições estimulantes que o ambiente celular. A piezoeletricidade e a condutividade surgem como duas propriedades importantes a considerar pois os estímulos mecânicos e elétricos são fundamentais para células ósseas, musculares e nervosas.
O PVDF é um dos materiais com maior coeficiente piezoelétrico e permite utilizar este material para estudar esta propriedade na entrega de estímulos elétricos e mecânicos nas células. Contudo, este material contém uma baixa condutividade e com vista a aumentar as suas propriedades elétricas depositou-se um polímero condutor que permite controlar o estímulo elétrico dado.
A produção de fibras por electrospinning permitiu a produção de fibras orientadas O e NO. A caraterização das fibras puras de PVDF a nível das suas propriedades mecânicas permitiu descobrir um comportamento anisotrópico em relação à aplicação de uma tensão numa determinada direção das fibras orientadas. Esta descoberta é útil aquando da utilização destas fibras em diferentes aplicações em que seja necessário estimular mecanicamente as fibras.
Diversos processos de deposição de polímeros condutores foram realizados e diferentes amostras obtiveram valores de resistividade elétrica da superfície baixos, o que revela um aumento da condutividade das amostras. Contudo, nem todos os processos de revestimento de polímero condutor permitem a sua aplicação em engenharia de tecidos devido à sua toxicidade. Duas amostras permitiram continuar os testes de caraterização, uma amostra revestida com Ppy e outra com PANI, que possuíam a biocompatibilidade e condutividade necessárias à continuação do trabalho.
Estas amostras foram caraterizadas morfologicamente e apresentaram um revestimento uniforme em volta das fibras enquanto a nível mecânico verificou-se uma diminuição das suas propriedades mecânicas em ambas as amostras, mas com maior acentuação nas fibras de PANI.
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Por essa razão, os testes eletromecânicos e de proliferação celular foram realizados apenas nas fibras revestidas com Ppy. Em relação aos testes eletromecânicos, estes demonstraram que as fibras possuem um comportamento piezoresistivo, ou seja, com o aumento da deformação existe um aumento da resistência elétrica que diminuiu quando a fibra relaxa.
Os testes de proliferação indicam que apesar desta ocorrer nas amostras revestidas com Ppy, a adesão é menor que nas fibras de PVDF sem revestimento. Através das imagens obtidas por SEM consegue-se observar que nas fibras O as células seguem a direção das fibras contrariamente ao que acontece nas fibras NO.
5.2 TRABALHO FUTURO
Esta dissertação abriu novas possibilidades de investigação de polímeros inteligentes e a sua utilização conjunta.
Um próximo passo será testar estas amostras num bioreator e estimulá-las elétrica, mecânica e eletromecanicamente com células e perceber como os diferentes estímulos afetam o material e, por conseguinte, se permitem uma melhoria na proliferação e diferenciação celular.
Poderão ser produzidas novos materiais através de outros métodos, como por exemplo, blending, eletrodeposição ou através da alteração dos reagentes da reação.
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