Navegando por Palavras-chave "Arcabouços"

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    Avaliação do biovidro 45S5 modificado com Nb+5 na fabricação de arcabouço para engenharia tecidual
    (Universidade Federal de São Paulo (UNIFESP), 2019-02-18) Siqueira, Lilian De [UNIFESP]; Triches, Eliandra De Sousa [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Currently, various types of alloplastic grafts, known as scaffolds, have been developed for the treatment of bone defects caused by trauma and/or infection. Among the materials used to manufacture scaffolds, the 45S5® Bioglass stands out due to its excellent bioactivity and ease of preparation. This bioglass has the ability to form chemical bonds with both soft tissues (cartilages) and hard tissues (bones). Among the various processing methods cited in the literature for the production of bioactive glass scaffolds, gelcasting is a method that produces macroporous structures with interconnected and spherical pores and good mechanical strength. However, there are few reports in the literature about bioactive glass scaffolds produced by the gelcasting method. In the present work, bioglass derived from 45S5® (BG45S5) and 45S5® modified with niobium (Nb+5) (BGNb5 and BGNb10) were manufactured by fusion/cooling technique and used to manufacture scaffolds by gelcasting method for tissue engineering applications. The obtained bioglass were characterized by X-ray fluorescence (FRX), particle size by laser diffraction and differential scanning calorimetry (DSC). The obtained bioglass showed chemical composition close to the nominal ones and exhibited particle size ˂ 7 μm. A change in the profile of the DSC curves in relation to Tg and Tc of the bioglass can be observed due to the addition of Nb2O5 in the bioglass composition. Then, different thermal treatments (500 - 1000 ºC) were carried out in the bioglass to study the effect of the addition of Nb2O5 on the structural properties of the BG45S5 bioglass during the calcination process. To this end, the following investigations were performed: X-ray diffractometry (XRD), Fourier Transform Infrared (FTIR) spectroscopy and RAMAN spectroscopy. The MTT test was performed to select the best composition for the scaffolds. The bioglass presented a vitreous characteristic after the synthesis process, as well as the formation of the main crystalline phases: Na2CaSi2O6 and NaNbO3 after heat treatment. FTIR and Raman spectroscopy allowed a detailed understanding of the bioglass structure. For the BGNb's, the NbO6 octahedron enters the silicate network, sharing its vertices with the silicon tetrahedra to form O-Si-O-Nb-O-Si-O chains. The results of in vitro bioglass studies on the viability of osteoblasts show significant differences between BG45S5 and BGNb's. The BGNb10 bioglass presented better cell viability compared to BG45S5 and BGNb5. Thus, BG45S5 and BGNb10 bioglass scaffolds were prepared by the gelcasting method, where different amounts of foaming agent (0.1, 0.2 and 0.3% by mass) were tested. The obtained scaffolds were characterized by scanning electron microscopy (SEM), X-ray microtomography, X-ray diffractometry (XRD),mechanical resistance to compression and in vitro biological assays. The scaffolds produced presented macroporous structures, with interconnected and spherical pores. The BG45S5 bioglass scaffolds showed porosity between 70.7 ± 0.8 – 86.0 ± 1.2 % and compressive strength of 1.22 ± 0.7 and 0.78 ± 0.4 MPa, while BGNb10 bioglass scaffolds showed 89.2 ± 1.4 % porosity and compressive strength of 0.18 ± 0.03 MPa. In in vitro biological studies, all scaffolds showed cytocompatibility for human osteoblastic cells and bioactive properties using the SBF assay. However, BGNb10 bioglass scaffolds show a tendency for higher alkaline phosphatase activity (ALP) and higher degradation than BG45S5 bioglass scaffolds. Thus, the biological evaluation suggests a viable application of the macroporous scaffolds of BGNb10 bioglass for applications in the regeneration of the bone tissue.
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    Géis nanoestruturados por hidróxidos e óxidos metálicos: uma otimização de sistemas binários de solventes
    (Universidade Federal de São Paulo, 2023-02-28) Tabuti, Thiago Galeote [UNIFESP]; Triboni, Eduardo Rezende; http://lattes.cnpq.br/7907094933095175; http://lattes.cnpq.br/4081141430396271
    Uma nova metodologia para obtenção de NPs de ZnO baseada em um sistema Glicerol-Ureia (GU) foi criada na EEL-USP e vem sendo otimizada. No presente trabalho foi proposta a troca da ureia por isopropanol e avaliada a influência da proporção molar dos solventes e da temperatura. O resultado dessa substituição foi a obtenção de um gel nanoestruturado com ZnO. No método GU, explorou-se a inflência da quantidade molar dos reagentes sal de zinco:base hidroxílica e da temperatura, onde algumas condições foram determinantes para a formação total de ZnO ou para a obtenção do intermediário Zn(OH)2. Também foi testada uma nova abordagem com um sistema de borbulhamento de amônia em glicerol, que resultou na formação de ZnO com morfologia de agulhas. O método GI foi replicado para o precursor de magnésio, que resultou em um gel formado por Mg(OH)2, que posteriormente gerou novas possibilidades de calcinação (do gel ou do xerogel), resultando em conformações diferentes. A estrutura do gel permite amplas possibilidades de funcionalização a partir da utilização de aditivos para a formação de materiais híbridos e compósitos para determinadas aplicações. Nesse sentido, os géis contendo Zn(OH)2 e Mg(OH)2 foram misturados para formar um material hibrido com ZnO e MgO após a calcinação, o que resultou em morfologias diferentes das esperadas. Os materiais obtidos foram caracterizados por DRX, MEV, MET. Por fim, o ZnO obtido pelo método GU foi aplicado no recobrimento de arcabouços biomédicos e foi avaliada a sua atividade antimicrobiana, gerando resultados promissores.