Hidroxiapatita porosa foi produzida por meio de uma nova técnica de processamento, visando aplicações na área de implantes ósseos. A produção do material poroso é feita através da produção de espumas pela agitação de suspensões cerâmicas aquosas contendo tensoativos adequados. A solidificação que segue é obtida pela adição de reagentes iniciadores da polimerização in situ de monômeros orgânicos, inicialmente incluídos nas composições, formando um gel. Este método permite a produção de corpos com formatos de alta complexidade e elevada resistência mecânica com níveis de porosidade próximos de 90%vol, que suportam corte e torneamento no estado a verde. Os aditivos orgânicos são eliminados a 300 °C e sinterização a 1350 °C é efetuada para consolidação da matriz. A otimização da resistência mecânica decorre da combinação entre uma matriz cerâmica de alta densidade a uma estrutura de poros esféricos com diâmetros que variam de 20-1000 <FONT FACE="Symbol">m</font>m possuindo inter-conecções de aproximadamente 10-100 <FONT FACE="Symbol">m</font>m, dependendo da densidade. O material sinterizado foi avaliado quanto a sua citoxicidade, utilizando-se o método quantitativo de formação de colônias que calcula o índice de citotoxicidade IC50(%) após contato do extrato do material com células de mamíferos. Os resultados mostraram que o processo de fabricação e os reagentes utilizados não afetaram os baixos níveis de toxicidade do pó de hidroxiapatita que era originalmente de pureza biomédica.

When AISI 316L stainless steels are submitted to the nitriding process at temperatures lower than 450 °C, a high nitrogen content expanded austenite phase is formed, which shows higher hardness and higher pitting corrosion resistance compared to the untreated material. As a result, this material becomes adequate for biomedical application. The conditions of the nitriding technique, such as gas mixture, pressure, time and temperature, play an important role in some properties of the modified layer, including: thickness, hardness and N concentration along the layer. This paper explores a set of six samples of AISI 316L, nitrided at different times and temperatures, whose properties show important differences. The aim of this research is to investigate the correlation between the nitrided layer thickness (in the range of 0.77 to 11 µm) with both X-ray patterns characteristics and hardness measurements, which used two distinct loads. The results of this study show that: whereas the 3.6 gf load was suitable to measure the real hardness for four of the nitrided layers showing thickness ≥ 2.9 µm, the 50 gf load measured a substrate contribution, probably even for the highest thickness, 11 µm. Moreover, analyzing different reflections of the X-ray patterns showed evidence of the clear consistency between the X-Ray depths and the nitrided layer thicknesses: if the layer thickness is lower than the penetration depth of X-rays, two phases (austenite and expanded substrate) are present. If the layer thickness is higher, only the austenite is observed. Finally, concerning the citotoxicity property, all the samples, nitrided or not, were approved in the test for biocompatibility, indicating their potential use for biomedical applications.

Chitosan based membranes to be applied on wound healing as topical drug delivery systems were developed by graft copolymerization of acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) onto chitosan using cerium ammonium nitrate as chemical initiator. Evidence for graft copolymerization of the vinyl monomers onto chitosan was obtained by FTIR and DMTA. Swelling degree, cytotoxicity, thrombogenicity and haemolytic activity of these membranes were evaluated. Chitosan-graft-AA-graft-HEMA showed to be the best matrix for drug delivery systems than chitosan-graft-AA because it retains good swelling properties, but the content in HEMA has improved cytocompatibility, hemocompatibility and thrombogenic character.

Polyaniline (PANI) and their charge transfer complexes are engineering materials that continue to attract considerable attention from engineers due to their unique electrochemical behavior, environmental stability and high degree of processability. Extensive works on the preparation of electrically conductive PANI blends containing a polymeric matrix having desirable physical and good mechanical characteristics have pointed as a promising route to overcome the PANI intractabilities. This paper reports the electrical properties of the dichromated PANI/poly(vinyl alcohol) (PANI:Cr3+/PVA) blends. Doped polyaniline powder in the emeraldine base form was synthesized by the classical chemical oxidation of aniline with ammonium persulfate as the oxidant in the presence of chromium (Cr3+). The SEM (Phillips XL 30) was used to understand the changes occurring in the conductivity to a microstructure level. The distribution of PANI:Cr3+ (50% w/w) in the host polymer (PVA) show some tendency to occur in "flocculated structures". The samples were cut into circular shapes to form films about 500 microns thick. Electrical contacts were made by sputtering gold over sample surfaces. We have carried out impedance spectroscopy measurements in the range of 20Hz to 1MHz. Measurements carried at 100K and 250K indicates that thermally activated carrier process between PANI:Cr3+ grains in the PANI:Cr3+/PVA blend sample are responsible for its high temperature conductivity.