Navegando por Palavras-chave "Gelcasting Method"

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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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    Processamento e Caracterização de Scaffolds de β-Fosfato Tricálcico pelo Método de Gelcasting com Incorporação de Nanopartículas para Atividade Antimicrobiana
    (Universidade Federal de São Paulo (UNIFESP), 2020-02-14) Barbosa, Lucas [UNIFESP]; Triches, Eliandra De Sousa [UNIFESP]; Universidade Federal de São Paulo
    Tissue engineering and regenerative medicine are highly relevant to the science of biomaterials, promoting advances in the treatment and recovery of patients with problems caused by diseases, injuries and fractures. Recent studies in tissue engineering have sought to develop multifunctional scaffolds that in addition to having regenerative capacity, have antimicrobial properties through the incorporation of antimicrobial agents, providing a better recovery to the patient and avoiding new surgical procedures for treatment or removal of the implant, since inflammations and infections are often caused by microorganisms. For the production of ceramic scaffolds for bone tissue regeneration, tricalcium β-phosphate (β-TCP) stands out due to its chemical stability and more suitable resorption speed for bone implants. Among the antimicrobial agents that have been studied are metallic nanoparticles, such as silver, and chemical compounds, such as methylene blue. Thus, this work aimed to obtain β-TCP scaffolds by the gelcasting method applied to foams with the incorporation of methylene blue and silver nanoparticles in order to confer antimicrobial properties. For this, the obtained β-TCP scaffolds were immersed in the silver nanoparticles solution and stirring by ultrasonic. Methylene blue was incorporated by dripping the solution into the scaffolds. The synthesized ceramic powder presented the crystalline phase of interest, β-TCP, average particle size after grinding 1.56 μm and density 2.99 g/cm³. Regarding antimicrobial agents, silver nanoparticles had an average hydrodynamic diameter of 39 ± 2 nm, with maximum absorption in the UV-visible spectrum at 429 nm and the methylene blue solution had a concentration of 1.044 mM, with maximum absorption in the UV-visible spectrum at 654 nm. In turn, the β-TCP scaffolds had porosity of 81 ± 2 % and mechanical compressive strength of 1.3 ± 0.5 MPa with spherical and interconnected pores. The test to evaluate the antimicrobial activity, in relation to S. aureus bacteria, of the scaffolds incorporated with antimicrobial agents revealed that the studied samples had little inhibitory action. It is understood that it is not enough to just incorporate an agent with a high antimicrobial capacity into the scaffold, but to understand how this agent will be incorporated into the scaffold and whether this incorporation will leave it in contact with the microorganism during the antimicrobial activity test. Therefore, it was possible to obtain β-TCP scaffolds, incorporate them with antimicrobial agents and although they have little inhibitory action, it was possible to observe the relevance of the research and guide the studies for future work.