Study on production methods of Bioglass Porous Structures for Bone Tissue Engineering

• Autor(a) principal: Carmo, Francisco Luís Araújo do
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/47636
• topic: Bioglass; ICCs; bioglass based cement; 3D printing; bone tissue engineering; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais

This works’ objective was to study and produce bioglass based porous structures for bone tissue engineering. Three different production methods were studied as well as different bioglass sol-gel systems such as: 45S5 Bioglass (45% SiO2; 24,5% CaO; 24,5%Na2O; 6% P2O5), 80S20CC Bioglass (80% SiO2; 20% CaO) and 80S5P15C (80% SiO2; 5% P2O5; 15% CaO) (% mol). In the first method a study on inverted colloidal crystals (ICCs) was made. To achieve these type of structure polystyrene microspheres were produced through a microfluidic apparatus. Microspheres (~300 μm) were then introduced in a Teflon container to organize them into a hexagonal closed pack structure. Posteriorly a thermal treatment was made to promote the adhesion between spheres allowing for the production of the Colloidal crystals (CCs). Using different methods, bioglass sol-gel impregnation was achieved and thermal treatments above 900℃ were performed to promote densification. Unfortunately, it was not possible to produce an ICC structure due to the reduced mass of bioglass that was impregnated in the CCs.. For the second method, the technique of lyophilization was used. In the sol-gel production, different solids concentrations were studied at 10, 12.5 and 15%. These solutions were filled into syringes, frozen using liquid nitrogen and lyophilized. Although some structures were produced, they had a lot of pore irregularity which made them brittle and difficult to handle. A sintering process was done in an attempt to densify them but without success. In another approach, the production of a bioglass based cement was done with the purpose of obtaining 3D printed porous structures. Within the various optimization steps of the production method, the optimization of the printing slurry and the printing parameters were the most important. After these improvements, 3D structures were printed and sintered at 1100 ℃. Scanning Electron Microscopy (SEM) images allowed the presence of a porous surface to be detected. The density and porosity of the structures were evaluated. Density values of 1,43 g/cm3 and porosity of 42% were obtained. In mechanical compression studies the maximum value reached was 6.5 MPa for the compressive strength and Young's modulus was calculated with values in the order of 80 MPa. XRD and FTIR studies allowed to identify the presence of amorphous calcium phosphates and the presence of silicates in sintered samples at 1100 ℃.