RESUMO Os hidrogéis, redes poliméricas reticuladas capazes de absorver e reter uma grande quantidade de água devido à sua natureza hidrofílica, chamam a atenção para aplicações na Engenharia Tecidual. Ainda, esses materiais oferecem o potencial de projetar arcabouços partindo do seu comportamento pseudoplástico, o que é fundamental para impressão tridimensional (3D) baseada em extrusão. A adição de Laponita, um nanosilicato bidimensional em forma de disco, permite modificar o comportamento reológico de alguns géis, criando uma condição otimizada. Neste estudo, foi realizada a caracterização reológica do hidrogel compósito PEG-Laponita-alginato (PL-Alg) e de seu gel precursor PEG-Laponita (PL), visando futuramente a bioimpressão 3D. Inicialmente, foi avaliado o comportamento reológico de diferentes concentrações de Laponita no compósito PL. Verificou-se que a viscosidade da solução de PEG aumentou drasticamente como uma função da adição de Laponita, de modo que se observou um comportamento reológico não-Newtoniano fortemente pseudoplástico. O efeito dos diferentes teores de Laponita também pode ser notado para o compósito (PL-Alg), mantendo-se fixa a concentração de PEG e alginato, sendo este último adicionado com o intuito de ser um segundo precursor de rede para reticular o hidrogel de PEG-Laponita. Ainda, todos os compósitos apresentaram uma recuperação parcial da viscosidade em função do tempo, após a aplicação de cisalhamento, parâmetro a ser considerado no desenvolvimento de biotintas. Os arcabouços de PL-Alg foram impressos contendo até 10 camadas e colocados em uma solução de CaCl2 para a reticulação das cadeias do alginato. Posteriormente, testes in vitro foram realizados, mostrando que a dissolução da rede do hidrogel compósito foi mais crítica para a amostra com 5% de Laponita. Em conclusão, para trabalhos futuros deverá ser considerada a maneira mais apropriada de reticulação da cadeia de PEG, para melhorar as propriedades mecânicas e a resistência à degradação, viabilizando a utilização do sistema PEG-Laponita-alginato para aplicações em bioimpressão 3D.

ABSTRACT Hydrogels, crosslinked polymeric networks capable of absorbing and retaining a large number of water due to their hydrophilic nature, draws attention to Tissue Engineering applications. These materials offer the potential to design scaffolds based on their pseudoplastic behavior, which is essential for extrusion-based three-dimensional (3D) printing. The addition of Laponite, a two-dimensional disk-shaped nanosilicate, allows modifying the rheological behavior of some gels, creating an optimized condition for 3D printing. In this study, the rheological characterization of the composite hydrogel PEG-Laponite-Alginate (PL-Alg) and its precursor gel PEG-Laponite (PL) was carried out, aiming in the future for 3D bioprinting of constructs. Initially, the rheological behavior of different concentrations of Laponite in the PL composite was evaluated. The viscosity of the PEG-400 increased dramatically as a function of the addition of Laponite, characterizing a strong shear-thinning and solid-like rheological behavior, ideal for 3D printing. The effect of different levels of Laponite can also be noted for the composite (PL-Alg), keeping the concentration of PEG400 and alginate fixed, the latter being added as a second network precursor to crosslink the PEG-Laponite hydrogel. Besides, all composites showed a partial recovery of viscosity as a function of time after the application of shear. This rheological parameter must be considered in the development of a bioink. PL-Alg scaffolds containing Laponite were printed containing up to 10 layers and placed in a CaCl2 solution to promote crosslinking of the alginate chains. Subsequently, in vitro tests were performed in phosphate-buffered saline solution, showing that the dissolution of the composite hydrogel network was more critical for the sample with 5% Laponite. In conclusion, for future work, the most appropriate way of crosslinking the PEG chain should be considered to improve the mechanical properties and the resistance to degradation, enabling the use of the PEG-Laponite-Alginate system as a bioink for 3D bioprinting applications.

ABSTRACT 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.

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.

Resumo O objetivo deste artigo é identificar, quantificar e categorizar a ocorrência de notificações de eventos adversos e queixas técnicas relacionados ao uso de cateter vascular recebidas pelo sistema NOTIVISA no período de janeiro de 2007 a junho de 2016. Estudo descritivo, retrospectivo, documental, com abordagem quantitativa. Os dados solicitados e fornecidos pela Anvisa foram analisados e apresentados na forma de gráficos e tabelas. Fizeram parte do estudo 4682 notificações de queixas técnicas e 671 de eventos adversos. Houve aumento progressivo das notificações no período estudado. Quanto ao tipo de queixa técnica, a maioria delas se referiu a ‘produto com suspeita de desvio de qualidade’ sendo em maior quantidade o motivo ‘rompimento do cateter durante o procedimento’. O evento adverso mais notificado foi ‘Cateter rompeu na veia e migrou para outra parte do corpo’. Destaca-se que no período estudado ocorreram 4 notificações de óbitos, a forma mais grave de evento adverso. O estudo permitiu visualizar a importância da vigilância pós-comercialização dos cateteres vasculares além de fornecer um panorama de seu uso, o que pode apoiar ações de Tecnovigilância e subsidiar as políticas públicas voltadas a esse produto.

Abstract This article identifies, quantifies and categorizes adverse event notifications and technical complaints related to the use of vascular catheters, received by the Notivisa system in the period from January 2007 to June 2016. It is a descriptive, retrospective, documental study with a quantitative approach. Data requested and supplied by Anvisa were analyzed and presented in the form of charts and tables. The study covered 4,682 notifications of technical complaints, and 671 adverse events. There was a progressive increase in notifications during the period studied. As to the type of technical complaint, the majority referred to ‘suspected quality failings’, the largest component being due to ‘catheter rupture during procedure’. The adverse event most notified was ‘catheter broke in the vein and migrated to another part of the body’. In the period studied there were four notifications of deaths, the most severe level of adverse event. The study made it possible to visualize the importance of after-sales surveillance of vascular catheters, as well as supplying a wide-ranging overview of their use. Provision of this overview could support technical surveillance activities and serve as input for public policies relating to this product.

Resumo O objetivo deste artigo é identificar, quantificar e categorizar a ocorrência de notificações de eventos adversos e queixas técnicas relacionados ao uso de cateter vascular recebidas pelo sistema NOTIVISA no período de janeiro de 2007 a junho de 2016. Estudo descritivo, retrospectivo, documental, com abordagem quantitativa. Os dados solicitados e fornecidos pela Anvisa foram analisados e apresentados na forma de gráficos e tabelas. Fizeram parte do estudo 4682 notificações de queixas técnicas e 671 de eventos adversos. Houve aumento progressivo das notificações no período estudado. Quanto ao tipo de queixa técnica, a maioria delas se referiu a ‘produto com suspeita de desvio de qualidade’ sendo em maior quantidade o motivo ‘rompimento do cateter durante o procedimento’. O evento adverso mais notificado foi ‘Cateter rompeu na veia e migrou para outra parte do corpo’. Destaca-se que no período estudado ocorreram 4 notificações de óbitos, a forma mais grave de evento adverso. O estudo permitiu visualizar a importância da vigilância pós-comercialização dos cateteres vasculares além de fornecer um panorama de seu uso, o que pode apoiar ações de Tecnovigilância e subsidiar as políticas públicas voltadas a esse produto.

Abstract This article identifies, quantifies and categorizes adverse event notifications and technical complaints related to the use of vascular catheters, received by the Notivisa system in the period from January 2007 to June 2016. It is a descriptive, retrospective, documental study with a quantitative approach. Data requested and supplied by Anvisa were analyzed and presented in the form of charts and tables. The study covered 4,682 notifications of technical complaints, and 671 adverse events. There was a progressive increase in notifications during the period studied. As to the type of technical complaint, the majority referred to ‘suspected quality failings’, the largest component being due to ‘catheter rupture during procedure’. The adverse event most notified was ‘catheter broke in the vein and migrated to another part of the body’. In the period studied there were four notifications of deaths, the most severe level of adverse event. The study made it possible to visualize the importance of after-sales surveillance of vascular catheters, as well as supplying a wide-ranging overview of their use. Provision of this overview could support technical surveillance activities and serve as input for public policies relating to this product.