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Desenvolvimento de um material estratificado para substituição da cartilagem articular: hidrogel à base de PVA unido a um scaffold de HAp
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Resumo(s)
São diversos os traumas e patologias que desencadeiam defeitos na cartilagem articular que,
contrariamente ao tecido ósseo, é um tecido avascular e consequentemente com baixa
capacidade de regeneração. Doenças como a osteoartrite, uma patologia degenerativa
progressiva que afeta a cartilagem articular, resulta não apenas na perda gradual das
propriedades mecânicas e de absorção de impacto da cartilagem, mas também no aumento da
dor, inflamação crónica e limitação funcional das articulações. Esta condição leva a uma redução
significativa da mobilidade e autonomia dos pacientes. Existem várias alternativas em estudo
para a minimização deste problema, sendo uma delas a substituição da car5lagem danificada
por um biomaterial.
Como tal, este trabalho teve como objetivo desenvolver uma estrutura estratificada com
diferentes propriedades biomecânicas e funcionais a fim de substituir adequadamente a
cartilagem articular. Para isso, foram produzidos por cast-drying, vários hidrogéis compostos por
15% pp de PVA, 4,5% pp de PVP e diferentes concentrações de NFCs (0,4 % pp, 0,8% pp e 1,1%
pp) e submetidos posteriormente a um recozimento a 140°C. Estes hidrogéis foram caraterizados
em termos da quan5dade de água absorvida, módulo tangente à compressão e coeficiente de
atrito, de forma a ser selecionado um hidrogel com propriedades semelhantes à da car5lagem.
Tendo em vista a seleção do hidrogel também foram realizados os mesmos ensaios em plugs de
car5lagem natural de porco.
Nos ensaios de intumescimento, todos os hidrogéis revelaram uma taxa significa5vamente
inferior à da car5lagem natural, enquanto os módulos tangentes à compressão dos hidrogéis
4,5PVP0CR e 4,5PVP0,8CR ob5dos foram semelhantes aos da car5lagem. Rela5vamente ao
coeficiente de atrito, os valores ob5dos para os diferentes hidrogéis com NFCs foram
semelhantes ao da car5lagem natural. Por ter as propriedades mais adequadas, o hidrogel
4,5PVP0,8CR foi selecionado para ser unido a scaffolds de hidroxiapa5te (ob5dos por impressão
3D) com porosidade controlada a fim de facilitar a integração do hidrogel no osso subcondral. O
conjunto foi subme5do a testes de adesão, os quais demonstraram que a união entre os dois
materiais é suficiente para esta aplicação.
De forma geral, este trabalho demonstra que é possível desenvolver um material que consiste
num hidrogel unido a um scaffold (formando um laminado) com potencial para ser usado como
subs5tuto da car5lagem ar5cular.
There are many traumas and pathologies that trigger defects in auricular cartilage which, unlike bone tissue, is an avascular tissue and consequently has a low capacity for regeneration. Diseases such as osteoarthritis, a progressive degenerative pathology that affects articular cartilage, results not only in the gradual loss of the cartilage's mechanical and impact-absorbing properties, but also in increased pain, chronic inflammation and functional limitation of the joints. This condition leads to a significant reduction in patients' mobility and autonomy. There are several alternatives being studied to minimize this problem, one of which is the replacement of damaged cartilage with a biomaterial. So, this work aimed to develop a layered structure with different biomechanical and functional properties in order to adequately replace articular cartilage. To this end, several hydrogels composed of 15% pp PVA, 4.5% pp PVP and different concentrations of NFCs (0.4% pp, 0.8% pp and 1.1% pp) were produced by cast-drying and subsequently annealed at 140°C. These hydrogels were characterized in terms of the amount of water absorbed, tangent modulus to compression and coefficient of friction, in order to select a hydrogel with properties similar to those of cartilage. In order to select the hydrogel, the same tests were also carried out on natural pig cartilage plugs. In the swelling tests, all the hydrogels showed a significantly lower rate than natural cartilage, while the tangent moduli to compression of the 4.5PVP0CR and 4.5PVP0.8CR hydrogels obtained were similar to those of cartilage. With regard to the coefficient of friction, the values obtained for the different hydrogels with NFCs were similar to those of natural cartilage. As it had the most suitable properties, the 4.5PVP0.8CR hydrogel was selected to be bonded to hydroxyapatite scaffolds obtained by 3D printing with controlled porosity in order to facilitate the integration of the hydrogel into the subchondral bone. The set was subjected to adhesion tests, which showed that the bond between the two materials is sufficient for this application. Overall, this work demonstrates that it is possible to develop a material consisting of a hydrogel joined to a scaffold (forming a laminate) with the potential to be used as a substitute for articular cartilage.
There are many traumas and pathologies that trigger defects in auricular cartilage which, unlike bone tissue, is an avascular tissue and consequently has a low capacity for regeneration. Diseases such as osteoarthritis, a progressive degenerative pathology that affects articular cartilage, results not only in the gradual loss of the cartilage's mechanical and impact-absorbing properties, but also in increased pain, chronic inflammation and functional limitation of the joints. This condition leads to a significant reduction in patients' mobility and autonomy. There are several alternatives being studied to minimize this problem, one of which is the replacement of damaged cartilage with a biomaterial. So, this work aimed to develop a layered structure with different biomechanical and functional properties in order to adequately replace articular cartilage. To this end, several hydrogels composed of 15% pp PVA, 4.5% pp PVP and different concentrations of NFCs (0.4% pp, 0.8% pp and 1.1% pp) were produced by cast-drying and subsequently annealed at 140°C. These hydrogels were characterized in terms of the amount of water absorbed, tangent modulus to compression and coefficient of friction, in order to select a hydrogel with properties similar to those of cartilage. In order to select the hydrogel, the same tests were also carried out on natural pig cartilage plugs. In the swelling tests, all the hydrogels showed a significantly lower rate than natural cartilage, while the tangent moduli to compression of the 4.5PVP0CR and 4.5PVP0.8CR hydrogels obtained were similar to those of cartilage. With regard to the coefficient of friction, the values obtained for the different hydrogels with NFCs were similar to those of natural cartilage. As it had the most suitable properties, the 4.5PVP0.8CR hydrogel was selected to be bonded to hydroxyapatite scaffolds obtained by 3D printing with controlled porosity in order to facilitate the integration of the hydrogel into the subchondral bone. The set was subjected to adhesion tests, which showed that the bond between the two materials is sufficient for this application. Overall, this work demonstrates that it is possible to develop a material consisting of a hydrogel joined to a scaffold (forming a laminate) with the potential to be used as a substitute for articular cartilage.
Descrição
Palavras-chave
Cartilagem articular Hidrogel Álcool Polivinílico Polivinilpirrolidona Nanofibras de Celulose Scaffold Articular cartilage Hydrogel Polyvinyl Alcohol Polyvinylpyrrolidone Cellulose Nanofibers