Publicação
Biomaterials based on natural polymers and inspired by the sea
| Resumo: | Marine mussels present an unusual amino acid, 3, 4-dihydroxy-L-phenylalanine (DOPA) obtained by postranslational modification of tyrosine which is used to stick in a various substrates, either inorganic or organic. The explanation for these adhesion properties is due to the presence of ortho-dihydroxyphenyl group, known as catechol group, present in DOPA and its analog dopamine. Inspired by mussel adhesive proteins (MAPs) and its adhesive properties, many efforts have been carried out in order to mimic the incredible adhesive properties of these mussels, either in two-dimensional or three-dimensional materials. In this present master’ thesis, bioglass and silver doped bioglass nanoparticles were produced through the sol-gel technique. Bioglass nanoparticles (BGNPs) have much importance in the biomedical field, because they can interact with bone without creating a fibrous capsule. Furthermore, the silver presence in the bioglass network allows antibacterial properties. Eight different thermal treatments were done in order to study its influence on surface morphology and bioactivity properties. The result showed that all heat-treated and untreated nanoparticles showed similar surface morphology. Moreover, all studied samples induced the formation of hydroxyapatite, structurally and chemically similar to the mineral charge of bone, on its surface. Moreover, free-standing films were developed using the layer-by-layer methodology. For that, chitosan was chosen as poly(cation) and hyaluronic acid and hyaluronic acid-dopamine conjugate were chosen as poly(anions). This modification was done in order to improve the films’ adhesive properties. Also, silver doped bioglass nanoparticles were included as nanofiller to improve its mechanical properties. These nanocomposites were studied by different characterization techniques. The Ag-BG-NPs percentage present in the free-standing films was evaluated through thermogravimetric tests. Bioactivity tests were performed and revealed that these films induce the hydroxyapatite formation on its surface and the silver presence in the bioglass network allowed an effective antibacterial performance. Finally, three-dimensional structures, hydrogels, were produced using chitosan and bioglass nanoparticles heat-treated at 700ºC during three hours. The dynamic mechanical tests revealed that the bioglass nanoparticles addition led to higher mechanical properties. Also, different formulations of a catechol-chitosan-conjugate were successfully synthetized and studied by ultraviolet-visible spectroscopy. The outcomes of this master’ thesis revealed that the produced silver doped bioglass nanoparticles, free-standing films and hydrogels could be used in the orthopedic area or dental applications. |
|---|---|
| Autores principais: | Pereira, Paulo Renato da Silva |
| Assunto: | Engenharia e Tecnologia::Outras Engenharias e Tecnologias |
| Ano: | 2016 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Marine mussels present an unusual amino acid, 3, 4-dihydroxy-L-phenylalanine (DOPA) obtained by postranslational modification of tyrosine which is used to stick in a various substrates, either inorganic or organic. The explanation for these adhesion properties is due to the presence of ortho-dihydroxyphenyl group, known as catechol group, present in DOPA and its analog dopamine. Inspired by mussel adhesive proteins (MAPs) and its adhesive properties, many efforts have been carried out in order to mimic the incredible adhesive properties of these mussels, either in two-dimensional or three-dimensional materials. In this present master’ thesis, bioglass and silver doped bioglass nanoparticles were produced through the sol-gel technique. Bioglass nanoparticles (BGNPs) have much importance in the biomedical field, because they can interact with bone without creating a fibrous capsule. Furthermore, the silver presence in the bioglass network allows antibacterial properties. Eight different thermal treatments were done in order to study its influence on surface morphology and bioactivity properties. The result showed that all heat-treated and untreated nanoparticles showed similar surface morphology. Moreover, all studied samples induced the formation of hydroxyapatite, structurally and chemically similar to the mineral charge of bone, on its surface. Moreover, free-standing films were developed using the layer-by-layer methodology. For that, chitosan was chosen as poly(cation) and hyaluronic acid and hyaluronic acid-dopamine conjugate were chosen as poly(anions). This modification was done in order to improve the films’ adhesive properties. Also, silver doped bioglass nanoparticles were included as nanofiller to improve its mechanical properties. These nanocomposites were studied by different characterization techniques. The Ag-BG-NPs percentage present in the free-standing films was evaluated through thermogravimetric tests. Bioactivity tests were performed and revealed that these films induce the hydroxyapatite formation on its surface and the silver presence in the bioglass network allowed an effective antibacterial performance. Finally, three-dimensional structures, hydrogels, were produced using chitosan and bioglass nanoparticles heat-treated at 700ºC during three hours. The dynamic mechanical tests revealed that the bioglass nanoparticles addition led to higher mechanical properties. Also, different formulations of a catechol-chitosan-conjugate were successfully synthetized and studied by ultraviolet-visible spectroscopy. The outcomes of this master’ thesis revealed that the produced silver doped bioglass nanoparticles, free-standing films and hydrogels could be used in the orthopedic area or dental applications. |
|---|