CECILIA CHAVES GUEDES E SILVA

CECILIA CHAVES GUEDES E SILVA

(Fonte: Lattes)

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Possui graduação em Engenharia de Materiais pela Universidade Presbiteriana Mackenzie (1997), mestrado em Tecnologia Nuclear Aplicações pelo Instituto de Pesquisas Energéticas e Nucleares (2000) e doutorado em Tecnologia Nuclear Materiais pelo Instituto de Pesquisas Energéticas e Nucleares (2005). Atualmente é pesquisador do Instituto de Pesquisas Energéticas e Nucleares. Tem experiência na área de Engenharia de Materiais, atuando principalmente nos seguintes temas: materiais cerâmicos, biomateriais e materiais nucleares. (Texto extraído do Currículo Lattes em 08 out. 2021)

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Influence of silicon, strontium and aluminum oxides on silicon nitride ceramics for bone replacements
2020 - NASCIMENTO, SERGIO F. do; RODAS, ANDREA C.D.; CARVALHO, FLAVIO M. de S.; HIGA, OLGA Z.; SILVA, CECILIA C.G. e
Although silicon nitride ceramics have been shown very propitious to be used for bone replacements, some characteristics can be controlled to improve their osseointegrations process. One of them is the intergranular phase whose composition can be specified to stimulate mineralization and osteoblastic production. In this paper, the intergranular glassy phase was projected in order to contain silicon, strontium and aluminum oxides. Silicon nitride samples containing different contents of SiO2, SrO and Al2O3 were sintered at 1815oC for 1 hour and characterized by scanning electron microscopy and X-ray diffraction. Hardness and fracture toughness were determined by Vickers hardness test and compressive strength was evaluated using an universal material testing machine. The biological behavior was studied in regard to cytotoxicity and cell proliferation by means of in vitro experiments. The samples reached high densities (higher than 95 %TD), total α→β-Si3N4 transformation, fracture toughness higher than 6.5 MPa.m1/2, compressive strength up to 2500 MPa and Vickers hardness less than 9.8 GPa. All samples were non-cytotoxic and able to promote cell proliferation with great potential to be used as components for bone replacements. However, that sample with high content of strontium had the best results of cell proliferation, proving the importance of a careful choice of intergranular phase composition in silicon nitride ceramics.
Silicon nitride with titania, calcia and silica additives for orthopaedic applications
2020 - GUEDES-SILVA, CECILIA C.; RODAS, ANDREA C.D.; CARVALHO, FLAVIO M.S.; HIGA, OLGA Z.; FERREIRA, THIAGO S.
Titanium, silicon and calcium ions have demonstrated positive effects in bone healing. Therefore, this paper investigates the densification, mechanical properties and in vitro biological behaviour of TiO2, together with SiO2 and CaO, on silicon nitride ceramics to be used in clinical applications. The results revealed that the sintered samples reached high values of relative density and fracture toughness, non-cytotoxicity as well as good ability to promote cell proliferation and form a layer of carbonated hydroxyapatite on their surfaces, after immersion in simulated body fluid. The sample with the highest amount of TiO2 reached the highest value of relative density and the best results of cell proliferation and fracture toughness, indicating the great potential to be explored by in vivo experiments for later application as intervertebral devices.
Estudo da bioatividade, adesão e proliferação de osteoblastos em biocompósitos de nitreto de silício
2017 - GUEDES-SILVA, C.C.; RODAS, A.C.D.; RIBEIRO, C.; HIGA, O.Z.; FERREIRA, T.S.
Este estudo avalia o comportamento biológico in vitro de cerâmicas de nitreto de silício denso contendo sílica, cálcia e alumina como constituintes da fase vítrea. Experimentos de bioatividade em SBF e testes de adesão e proliferação de celular com células MG-63 foram realizados nas superfícies das amostras. Os resultados mostraram que os materiais estudados formaram uma camada de apatita na superfície após 16 dias de imersão em SBF e que são capazes de promover a proliferação de osteoblastos e formação de matriz calcificada in vitro, demonstrando seu potencial para aplicações como dispositivos protéticos.
Silicon nitride ceramics with SiO2, SrO and Al2O3 additions for bone replacements
2018 - NASCIMENTO, S.F.; RODAS, A.C.D.; CARVALHO, F.M.S.; HIGA, O.Z.; GUEDES-SILVA, C.C.
The excellent mechanical properties of silicon nitride ceramics combined with their osseointegration ability and good image characteristics have increased their application potential as orthopedic and dental implants. In this work, we investigated the densification, microstructure and mechanical properties of silicon nitride with SiO2, SrO and Al2O3 additions (90Si3N4-6SiO2-4SrO, 90Si3N4- 6SiO2-3.86SrO-0.14Al2O3, 80Si3N4-10SiO2-10SrO, 80-Si3N4-10SiO2- 9.625SrO-0.375Al2O3, 80Si3N4-12SiO2-8SrO, 80-Si3N4-12SiO2-7.7SrO- 0.3Al2O3, in wt.%). This oxides combination should aid the sintering process and promote an intergranular phase with great in vivo reactivity in view of its importance in the new bone formation process. Hence, six different compositions were prepared by the conventional sintering method. Samples were ground, pressed and sintering at 1815o C for 1 hour under nitrogen atmosphere. The apparent density, phase and grain distributions as well as the hardness and fracture toughness were determined by means of Archimedes’ method, scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Vickers’ method. Also, in vitro test of cytotoxicity was performed for a preliminary biological evaluation. The results shown that samples reached ca. 97% of theoretical density and total beta-Si3N4 transformation. Hardness and fracture toughness values of 10 GPa and 7 MPa.m1/2, respectively, were obtained for all samples which were non-cytotoxic, suggesting their great potential for bone replacements in orthopedic surgeries and implantology.
Microstructure, mechanical properties and in vitro biological behavior of silicon nitride ceramics
2018 - GUEDES-SILVA, CECILIA C.; RODAS, ANDREA C.D.; SILVA, ANTONIO C.; RIBEIRO, CHRISTIANE; CARVALHO, FLAVIO M. de S.; HIGA, OLGA Z.; FERREIRA, THIAGO dos S.
The bioinert surface of silicon nitride ceramics led us to investigate the additions of SiO2, CaO and Al2O3 in order to aid the liquid phase sintering and improve the mechanical properties and biological behavior of the final materials. The sintered materials reached ca. 97% of theoretical density and total α→β-Si3N4 transformation. The samples had relatively high values of fracture toughness while their elastic modulus values were lower than those of conventional silicon nitride ceramics. Apatite deposits were observed on the surfaces analyzed after SBF (simulated body fluid) immersions, suggesting their bioactivity. Osteoblasts proliferation and calcified matrix were also detected as response to cells/ materials contact. This combination of properties suggests that all studied compositions are promising for applications in biomedical devices. Moreover, compositions with alumina additions and higher silica content had better in vitro biological behavior, densification and mechanical properties, suggesting greater potential to be used in bone substitute devices.
Testes de citotoxicidade para avaliação in-vitro de biocompósitos de nitreto de sílicio
2016 - RODAS, A.C.; GUEDES-SILVA, C.C.; FERREIRA, T.S.; HIGA, O.Z.
O nitreto de silício (Si3N4) é um material cerâmico que se mostra promissor para utilização em próteses ortopédicas e dentais, por apresentar elevadas propriedades mecânicas, capacidade de promover osteointegração, capacidade bactericida e características radiolucentes. Com o intuito de ampliar e otimizar a utilização desses materiais na área médica, novos biocompósitos densos de nitreto de silício, contendo uma fase bioativa livre de fósforo, foram obtidos por sinterização normal. No desenvolvimento de novos materiais, testes de biocompatibilidade necessitam ser realizados. Estes testes variam de análises físico-químicas a análises biológicas. Neste trabalho, o teste de citotoxicidade, considerado o teste padrão inicial para avaliação da biocompatibilidade por análise biológica, foi realizado em diferentes amostras densas de nitreto de silício com quantidades variadas de sílica e cálcia. O teste de citotoxicidade utilizado foi a análise indireta. Neste teste foi preparada a eluição do material em meio de cultura para cultivo de células, assim é possível avaliar a presença de componentes tóxicos que podem ser lixiviados do material e que apresentam potencial tóxico. Os eluentes são colocados em contato com uma camada confluente de células cultivadas aderidas e a viabilidade celular foi medida após 24 horas utilizando-se um corante vital, o MTS (que só reage com células vivas). Para todas as amostras analisadas, nenhuma delas apresentou citotoxicidade, variando a viabilidade celular dos eluídos de 94,7 a 104%.
Biocompósitos de nitreto de silício: caracterização e avaliação biológica in vitro
2016 - GUEDES-SILVA, C.C.; RODAS, A.C.D.; RIBEIRO, C.; CARVALHO, F.M.S.; GENOVA, L.A.; FERREIRA, T.S.; HIGA, O.Z.
Silicon nitride has been increasingly considered for biomedical applications owing to their high mechanical properties, osseointegration, bactericidal capacity and radiolucent characteristics. This study aims to evaluate the potential of silicon nitride ceramics containing silica and calcia in appropriate concentrations to have a bioactive intergranular phase, formed by a bioglass without phosphorus. Samples with 20 wt.% additives were sintered at 1815oC for 1 h under N2 atmosphere and analyzed in regard to density, crystalline phases, morphology and grain size as well as phases' distribution. Biological assessments by means of bioactivity tests in SBF (Simulated Body Fluid), cytotoxicity and osteoblast adhesion of MG63 cell line were performed. The results showed that samples reached around 97% of the theoretical density, high αβ-Si3N4 transformation and bioactivity evidenced by apatite formation on samples surface after testing in SBF. Silicon nitride samples exhibited non-cytotoxic and biocompatible behavior for propagation of human bone cells in vitro, demonstrating the high potential to be used as prosthetic devices and components.
Cytotoxic evaluation of silicon nitride based ceramics
2003 - GUEDES e SILVA, C.C.; HIGA, O.Z.; BRESSIANI, J.C.
Cytotoxic evaluation of silicon nitride-based ceramics
2004 - GUEDES e SILVA, C.C.; HIGA, O.Z.; BRESSIANI, J.C.