In situ immobilization of cobalt phthalocyanine on the mesoporous carbon ceramic SiO2/C prepared by the sol-gel process. Evaluation as an electrochemical sensor for oxalic acid

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The mesoporous carbon ceramics SiO2/20wt%C(S-BET = 160 m(2) g(-1)) and SiO2/50 wt%C(S-BET = 170 m(2) g(-1)), where C is graphite, were prepared by the sol-gel method. Scanning electron microscopy images and the respective element mapping showed that, within the magnification used, no phase segregation was detectable. The materials containing 20 and 50 wt% of C presented electric conductivities of 9.2 x 10(-5) and 0.49 S cm(-1), respectively. These materials were used as matrices to support cobalt phthalocyanine (CoPc), prepared in situ on their surfaces, to assure homogeneous dispersion of the electroactive complex in the pores of both matrices. The surface densities of cobalt phthalocyanine on both matrix surfaces were 0.014 mol cm(-2) and 0.015 mol cm(-2) for materials containing 20 and 50 wt% of C, respectively. Pressed disk electrodes made with SiO2/50 wt% C/CoPc and SiO2/20 wt% C/CoPc were tested as sensors for oxalic acid. The electrode was chemically very stable and presented very high sensitivity for this analyte, with a limit of detection, LOD = 5.8 x 10(-7) mol L-1. (C) 2010 Elsevier Ltd. All rights reserved.56312561261Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

SiO2/C/Cu(II)phthalocyanine as a biomimetic catalyst for dopamine monooxygenase in the development of an amperometric sensor

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)A mesoporous carbon ceramic SiO2/50 wt% C (S-BET = 170 m(2) g(-1)), where C is graphite, was prepared by the sol-gel method. This material was used as matrix to support copper phthalocyanine (CuPc), prepared in situ on their surface, to assure homogeneous dispersion of the electrocatalyst complex in the pores of the matrix. Pressed disk electrodes made with SiO2/C/CuPc was tested as amperometric sensors for dopamine. Under optimized conditions, at -20 mV vs SCE in 0.08 mol dm(-3) Britton-Robinson buffer (BRB) solution (pH = 6.0) containing 100 mu mol dm(-3) of H2O2, a linear response range for dopamine from 10 up to 140 mu mol dm(-3) was obtained with a sensitivity of 0.63 (+/- 0.006) nA dm(3) mu mol(-1) cm(-2) and the limit of detection LOD was 0.6 mu mol dm(-3). The sensors presented stable response during successive determinations. The repeatability, evaluated in terms of relative standard deviation of 1.37% for n = 10 and 10 mu mol dm(-3) dopamine. The response time was 1 s and lifetime 9 months. Finally, the sensor was tested to determine dopamine in the sample, and gives very good results for its determination. The presence of other phenols like catechol and resorcinol did not show any interference in the detection of dopamine on this electrode, even in the same concentration with the dopamine. (C) 2011 Elsevier Ltd. All rights reserved.56271011610121Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Dissolved O-2 sensor based on cobalt(II) phthalocyanine immobilized in situ on electrically conducting carbon ceramic mesoporous SiO2/C material

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)This work describes the preparation of mesoporous carbon ceramics SiO2/50 wt.% C (S-BET = 170 m(2) g(-1)), where C is graphite, by the sol-gel method. This material was used as a matrix to support cobalt phthalocyanine (CoPc), prepared in situ on their surface, to assure homogeneous dispersion of the electrocatalyst complex in the pores of the matrix. Pressed disk electrode made with SiO2/C/CoPc was used to analyze dissolved oxygen in water by an electrochemical technique in neutral media and dissolved O-2 was reduced at -0.23 V. The linear response range, sensitivity and detection limit obtained were 0.5-6.6 mg L-1, 2.16 mu A L mg(-1) and 0.01 mg L-1, respectively, by chronoamperometry. A mechanism involving two electrons in O-2 reduction was determined by cyclic voltammetry technique. The repeatability of the proposed sensor, evaluated in terms of relative standard deviation was 1.6% for 10 measurements of a solution of 6.5 mg L-1 oxygen. The sensor was applied to determine oxygen in pond and tap water samples showing to be a promising tool for this purpose. (c) 2012 Elsevier B.V. All rights reserved.177231238Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)INCTBioCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

In situ immobilization of nickel(II) phthalocyanine on mesoporous SiO2/C carbon ceramic matrices prepared by the sol-gel method: Use in the simultaneous voltammetric determination of ascorbic acid and dopamine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Three carbon ceramic materials with different porosities were prepared by the sol-gel method, using HNO3, HF, and HNO3/HF as catalysts and the surface areas (S-BET) of the products were determined as 246, 201, and 356 m(2) g(-1), respectively. The materials were characterized using N-2 sorption isotherms, scanning electron microscopy, and conductivity measurements. The matrices were used as supports for the in situ immobilization of Ni(II) phthalocyanine (NiPc) on their surfaces. XPS was used to determine the Ni/Si atomic ratios of the NiPc-modified materials. Pressed disk electrodes were prepared with the NiPc-modified matrices, and tested as sensors for dopamine. The electrode prepared using nitric acid showed excellent catalytic activity for the simultaneous determination of ascorbic acid (AA) and dopamine (DA), with sensitivities of 53.02 and 104.17 mu A mmol dm(-3), respectively. Good repeatability was achieved, with R.S.D. values of 3.67% (AA) and 3.53% (DA), as well as high stability. (C) 2012 Elsevier Ltd. All rights reserved.87140147Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Mortalidade perinatal e evitabilidade: revisão da literatura Perinatal mortality and evitability: a review

Neste artigo, realizou-se uma revisão da literatura sobre mortalidade perinatal com maior enfoque na evitabilidade desses óbitos. Foram pesquisadas, sobretudo, publicações da década de 90 nas bases Medline e Lilacs (América Latina e Caribe). Discutiram-se as dificuldades para a realização de estudos nesta área, ainda em número restrito no Brasil, em decorrência do grande subregistro de óbitos fetais e da má qualidade da informação nas declarações de óbitos. Foram apresentadas as principais propostas de classificação dos óbitos perinatais baseadas em enfoque de evitabilidade, com destaque para a classificação de Wigglesworth. Nesta abordagem, os óbitos perinatais foram relacionados a momentos específicos da assistência, sendo evidenciadas as possibilidades de sua prevenção. Recomenda-se o enfoque de evitabilidade para a abordagem da mortalidade perinatal no Brasil, dado que as taxas são ainda elevadas, a maioria dos óbitos é considerada evitável e poderia ser prevenida com a melhoria da assistência pré-natal, ao parto e ao recém-nascido, não apenas quanto à sua resolubilidade clínica, mas também à organização da assistência em sistemas hierarquizados e regionalizados, assegurando o acesso da gestante e do recém-nascido em tempo oportuno a serviços de qualidade.<br>This is a literature review onperinatal mortality focusing its evitability. A Medline and Lilacs (Latin-America and Caribbean) search was conducted for the 90s. There are few research studies on this subject in Brazil due to the great number of underreported fetal deaths and the low quality information provided in death certificates. Different proposals for perinatal death classification are presented. Most are based on grouping the underlying causes of deaths in a functional system in order to facilitate the analysis. In the Wigglesworth classification system, one of the most recommended methods, deaths are related to the different stages of care for pregnant women and children, evidencing the possibilities of their prevention. The evitability approach of perinatal deaths in Brazil is highly recommended, as mortality rates are still very high and most of the deaths are considered avoidable. Premature deaths could be avoided improving the quality of health care. Besides improving the medical assistance, the organization of health care regarding pre-natal, birth and neonatal care must also be better developed to ensure access to qualified assistance