Avaliação do estresse oxidativo induzido por superfícies de titânio

Commercially pure Titanium (cp Ti) is a material largely used in orthopedic and dental implants due to its biocompatibility properties. Changes in the surface of cp Ti can determine the functional response of the cells such as facilitating implant fixation and stabilization, and increased roughness of the surface has been shown to improve adhesion and cellular proliferation. Various surface modification methods have been developed to increase roughness, such as mechanical, chemical, electrochemical and plasma treatment. An argon plasma treatment generates a surface that has good mechanical proprieties without chemical composition modification. Besides the topography, biological responses to the implant contribute significantly to its success. Oxidative stress induced by the biomaterials is considered one of the major causes of implant failure. For this reason the oxidative potential of titanium surfaces subjected to plasma treatment was evaluated on this work. CHO-k1 cells were cultivated on smooth or roughed Ti disks, and after three days, the redox balance was investigated measuring reactive oxygen species (ROS) generation, total antioxidant capacity and biomarkers of ROS attack. The results showed cells grown on titanium surfaces are subjected to intracellular oxidative stress due to hydrogen peroxide generation. Titanium discs subjected to the plasma treatment induced less oxidative stress than the untreated ones, which resulted in improved cellular ability. Our data suggest that plasma treated titanium may be a more biocompatible biomaterial.

Aplicação do eletrocapilaridade na manipulação de microgotas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo da reciclagem mecânica de poli (cloreto de vinila) - PVC - proveniente deresíduos da construção civil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Quantificação e seqüênciamento do gene da transcriptase reversa em gatos naturalmente infectados com vírus da imunodeficiência felina tratado com AZT

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação do estresse oxidativo induzido por superfícies de titânio

Commercially pure Titanium (cp Ti) is a material largely used in orthopedic and dental implants due to its biocompatibility properties. Changes in the surface of cp Ti can determine the functional response of the cells such as facilitating implant fixation and stabilization, and increased roughness of the surface has been shown to improve adhesion and cellular proliferation. Various surface modification methods have been developed to increase roughness, such as mechanical, chemical, electrochemical and plasma treatment. An argon plasma treatment generates a surface that has good mechanical proprieties without chemical composition modification. Besides the topography, biological responses to the implant contribute significantly to its success. Oxidative stress induced by the biomaterials is considered one of the major causes of implant failure. For this reason the oxidative potential of titanium surfaces subjected to plasma treatment was evaluated on this work. CHO-k1 cells were cultivated on smooth or roughed Ti disks, and after three days, the redox balance was investigated measuring reactive oxygen species (ROS) generation, total antioxidant capacity and biomarkers of ROS attack. The results showed cells grown on titanium surfaces are subjected to intracellular oxidative stress due to hydrogen peroxide generation. Titanium discs subjected to the plasma treatment induced less oxidative stress than the untreated ones, which resulted in improved cellular ability. Our data suggest that plasma treated titanium may be a more biocompatible biomaterial.

Tratamento termoquímico do titânio auxiliado por plasma de ar - N2 - O2

Discs were grade II cp Ti oxynitride by plasma of Ar - N2 - O2 using different proportions of individual gases. These ratios were established from analysis of optical emission spectroscopy (OES) of plasma species. The proportions that resulted in species whose spectra showed an abrupt change of light intensity were chosen for this study. Nanohardness tests revealed that there was a correlation between the intensity of N2 + species with the hardness, because the treatments where they had a higher intensity, obtained a higher value nanohardness, although the crystalline phases have remained unchanged. With respect to topography, it was observed that in general, the surface roughness is related to the intensities of plasma species, because they may have different values depending on the behavior of the species. Images obtained by optical microscopy revealed a surface with grains of different colors to optical reflectance showed a peak of reflection in the red area. Measures the contact angle and surface tension showed hydrophilic properties and hydrophilic with little variation of polar and dispersive components of surface tension

Estudo de polímeros comerciais tratados a plasma em pressão atmosférica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Síntese e tratamento de materiais a plasma

Neste trabalho são apresentados resultados que demonstram algumas das possibilidades de processamento de materiais por técnicas de plasma. O primeiro conjunto de dados relata o efeito da potência de excitação do plasma na microestrutura e nas propriedades óticas e elétricas de filmes de carbono amorfo hidrogenado depositados em atmosferas de acetileno e argônio. Neste estudo, correlações entre as propriedades dos filmes e da fase plasma são realizadas com base nas caracterizações elétricas e óticas do plasma. Observa-se que a potência do sinal de excitação afeta diretamente a densidade de energia do plasma e, por conseguinte, as propriedades dos filmes. Variações nas proporções de hidrogênio e de sítios com hibridização sp2 foram constatadas. Filmes relativamente transparentes e com elevada resistência elétrica foram obtidos em plasmas de 50 W de potência. Na segunda etapa, discute-se o efeito da implantação iônica por imersão em plasmas nas propriedades de filmes de polímeros preparados em descargas de radiofreqüência de benzeno. As amostras foram expostas, por diferentes tempos, ao plasma de imersão de argônio e o comportamento da composição química, dureza, propriedades óticas e termodinâmicas de superfície dos filmes foi obtido em função do tratamento. Os filmes tornaram-se mais absorvedores e duros revelando perda de hidrogênio e aumento no grau de reticulação e de insaturação das cadeias carbônicas com o aumento do tempo de bombardeamento. Na parte final, demonstra-se a versatilidade e efetividade da técnica híbrida de implantação iônica e deposição por imersão em plasmas, na produção de filmes com diferentes composições químicas e propriedades de superfície, em função da proporção de gases nobres e reativos na descarga...

Tratamento termoquímico do titânio auxiliado por plasma de ar - N2 - O2

Discs were grade II cp Ti oxynitride by plasma of Ar - N2 - O2 using different proportions of individual gases. These ratios were established from analysis of optical emission spectroscopy (OES) of plasma species. The proportions that resulted in species whose spectra showed an abrupt change of light intensity were chosen for this study. Nanohardness tests revealed that there was a correlation between the intensity of N2 + species with the hardness, because the treatments where they had a higher intensity, obtained a higher value nanohardness, although the crystalline phases have remained unchanged. With respect to topography, it was observed that in general, the surface roughness is related to the intensities of plasma species, because they may have different values depending on the behavior of the species. Images obtained by optical microscopy revealed a surface with grains of different colors to optical reflectance showed a peak of reflection in the red area. Measures the contact angle and surface tension showed hydrophilic properties and hydrophilic with little variation of polar and dispersive components of surface tension

PARAFAC: uma ferramenta quimiométrica para tratamento de dados multidimensionais. Aplicações na determinação direta de fármacos em plasma humano por espectrofluorimetria

Since the last decade, the combined use of chemometrics and molecular spectroscopic techniques has become a new alternative for direct drug determination, without the need of physical separation. Among the new methodologies developed, the application of PARAFAC in the decomposition of spectrofluorimetric data should be highlighted. The first objective of this article is to describe the theoretical basis of PARAFAC. For this purpose, a discussion about the order of chemometric methods used in multivariate calibration and the development of multi-dimensional methods is presented first. The other objective of this article is to divulge for the Brazilian chemical community the potential of the combination PARAFAC/spectrofluorimetry for the determination of drugs in complex biological matrices. For this purpose, two applications aiming at determining, respectively, doxorrubicine and salicylate in human plasma are presented.

Diazepam e nordiazepam em plasma: métodos de extração líquido-líquido e em fase sólida no pré-tratamento de amostras para análise cromatográfica em fase líquida

Analysis of diazepam (DZP) and its active metabolite nordiazepam (NDZP) in plasma is commonly performed in clinical medicine to ensure proper therapeutic effects while minimizing the incidence of toxicity. This study aimed to optimize analytical parameters and compare two pre-treatment techniques, liquid-liquid (LLE) and solid phase extraction (SPE), as well as liquid chromatographic conditions to analyze simultaneously DZP and NDZP in plasma from 20 patients treated with a daily dose of 10 mg. Both techniques showed to be well in line with the international criteria for analytical validation, which permitted to quantify DZP (66.2 - 1148.6 ng mL-1) and NDZP (138.5 - 808.6 ng mL -1) in all samples. The correlation coefficients between SPE and LLE were respectively 0.9729 for DZP and 0.9643 for NDZP.

PARAFAC: uma ferramenta quimiométrica para tratamento de dados multidimensionais. Aplicações na determinação direta de fármacos em plasma humano por espectrofluorimetria

Since the last decade, the combined use of chemometrics and molecular spectroscopic techniques has become a new alternative for direct drug determination, without the need of physical separation. Among the new methodologies developed, the application of PARAFAC in the decomposition of spectrofluorimetric data should be highlighted. The first objective of this article is to describe the theoretical basis of PARAFAC. For this purpose, a discussion about the order of chemometric methods used in multivariate calibration and the development of multi-dimensional methods is presented first. The other objective of this article is to divulge for the Brazilian chemical community the potential of the combination PARAFAC/spectrofluorimetry for the determination of drugs in complex biological matrices. For this purpose, two applications aiming at determining, respectively, doxorrubicine and salicylate in human plasma are presented.

Plasma rico em plaquetas no tratamento de tendinite induzida em eqüinos: avaliação ultra-sonográfica

O objetivo deste trabalho foi estudar o efeito do plasma rico em plaquetas (PRP) no tratamento da tendinite induzida no tendão do músculo flexor digital superficial (TFDS) de eqüinos mediante avaliação ultra-sonográfica. Para isso foram utilizados seis eqüinos hígidos machos castrados, com idade de 8-15 anos (x=12 anos). A tendinite do TFDS foi provocada em ambos os membros torácicos, mediante a administração intratendínea de 2,5mg de colagenase (2,5mg.µL-1), sendo esse procedimento considerado o início da fase experimental. Doze dias após a indução da tendinite, os animais foram submetidos a dois tratamentos: sendo que na lesão efetuada no TFDS direito (grupo tratado, GT), foram administrados 2,5mL de PRP ativado com cloreto de cálcio a 0,0125mol.L-1, contendo concentrações variando de 320.000 a 500.000 plaquetas.µL-1; na tendinite do TFDS esquerdo (grupo controle, GC), foram injetados 2,5mL de solução salina a 0,9%. Após cinco dias, os animais foram submetidos à atividade física controlada e progressiva durante 30 dias. Os exames ultra-sonográficos foram realizados antes e após indução da tendinite (48 horas após e no 7º, 12º, 14º, 21º, 28º, 35º, 42º dias do experimento), sendo avaliado a área transversal do tendão (ATT), área transversal da lesão (ATL), o percentual da ATL, a intensidade e ecogenicidade da lesão, assim como o paralelismo das fibras colágenas. Os resultados revelaram redução (P<0,05) da ATL e do grau de ecogenicidade da lesão em função do tempo, mas com diferença (P<0,05) entre grupos apenas para ATL, com valores menores no GT. O tratamento com PRP proporciona maior redução da área da lesão, mensurada por ultra-sonografia.

Avaliação do desempenho do aço D6 tratado termicamente e netretado em plasma com gaiola catódica visando aplicação industrial

In this research there was an evaluation of the best conditions of nitriding in plasma within a cathodic cage at an atmosphere of 80% N2-20%H2 in samples of tool manganese steel AISI D6, cold working, treated thermally in the following conditions: tension relief, treated thermally to temperature of maximum heat, temperate heat and temperate and temperate heat. A pressure of 2.5mbar and temperatures of 400 and 300ºC com treatment time of two and three hours were used to evaluate its performance as cutting tool (punch) of bicycle backs. Hardness, micro-structural aspects (layer thickness, interface, grain size etc), and crystal phases on the surface were appraised. When treated to tension relief, thermally treated to maximum heat temperature, temperature and temperate heat, the samples presented hardness levels of 243HV, 231HV, 832HV, and 653HV, respectively. The best nitrification conditions were: four hours and 300ºC for heat samples. A superficial hardness of 1000HV and a 108µm thickness for the nitrided layer were found in these samples

Avaliação do desempenho do aço AISI D2 tratado termicamente e nitretado em plasma com gaiola catódica visando aplicação industrial

In the research, steel samples tool AISI D2, treated thermally, in the conditions: relief of tension, when maximum, seasoned and seasoned was treated thermally in the temperature of revenimento and revenida had been nitrited in plasma with cathodic cage, in atmosphere of 80%N2:20%H2. One used pressure of 2,5 mbar, 400 and 480°C temperatures with treatment time of 3 and 4 hours, with the objective to evaluate its performance in pipes cut tool. It was compared that the performance of the same steel when only thermally treated, both with tension relief. It was evaluated its hardness. Microstructural aspects (the layer thickness, interface, graisn size, etc) and crystalline phases on the surface. Besides, it was verified accomplishment possibility of nitriding simultaneous to annealing treatment. The tempering samples had presented hardness levels of 600 HV, while in nitrited samples these values had been 1100 HV