Visible LED-Based Instrumentation for Photometric Determination of Electroosmotic Flow in Microchannels

An instrumental setup for electroosmotic flow (EOF) determination in microfluidic devices is described. The system is based on a trinocular microscope and an integrated photodiode OPT101. The radiation was provided by a high-intensity white LED. For the determinations, patent blue V and methylene blue aqueous solutions were used. The setup was applied for EOF monitoring in hybrid toner/glass and PDMS microchips. For the toner/glass device, the EOF mobility was determined to be (5.75 ± 0.01) 10-4 cm² V-1 s-1 at pH 7.0. For PDMS devices the measured EOF mobility was (3.2 ± 0.1) 10-4 cm² V-1 s-1. Reproducible measurements were obtained in all experiments, which produced results with small errors. The proposed method was compared to the conventional current monitoring method

Visible LED-Based Instrumentation for Photometric Determination of Electroosmotic Flow in Microchannels

An instrumental setup for electroosmotic flow (EOF) determination in microfluidic devices is described. The system is based on a trinocular microscope and an integrated photodiode OPT101. The radiation was provided by a high-intensity white LED. For the determinations, patent blue V and methylene blue aqueous solutions were used. The setup was applied for EOF monitoring in hybrid toner/glass and PDMS microchips. For the toner/glass device, the EOF mobility was determined to be (5.75 ± 0.01) 10-4 cm² V-1 s-1 at pH 7.0. For PDMS devices the measured EOF mobility was (3.2 ± 0.1) 10-4 cm² V-1 s-1. Reproducible measurements were obtained in all experiments, which produced results with small errors. The proposed method was compared to the conventional current monitoring method.A instrumentação para a determinação fotométrica do fluxo eletrosmótico (EOF) em dispositivos microfluídicos é descrita neste trabalho. A instrumentação é baseada em componentes acessíveis e consiste em um microscópio trinocular e no fotodiodo integrado OPT101. Um diodo emissor de luz (LED) de alta intensidade foi utilizado como fonte de radiação. Para as determinações foram utilizadas soluções aquosas dos corantes azul patente V e azul de metileno. O sistema foi utilizado no monitoramento do EOF em microdispositivos de poli(dimetilsiloxano) (PDMS) e híbridos de toner/vidro. As mobilidades do EOF determinadas em pH 7,0 foram (5,75 ± 0,01)10-4 cm² V-1 s-1 e (3,2 ± 0,1)10-4 cm² V-1 s-1 para os dispositivos de toner/vidro e PDMS, respectivamente. Medidas reprodutíveis foram obtidas em todos os experimentos, levando a uma alta precisão na determinação. O método proposto foi comparado com o método tradicional de determinação do EOF que envolve a medida da corrente nos microcanais.736740Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Platinum and palladium complexes with 2,4-Dinitrophenylhydrazine: synthesis and cytotoxic activity

New complexes of platinum and palladium were isolated with 2,4-dinitrophenylhydrazine (2,4-DNPH). These complexes were characterized and the results shown that the ligand is coordinated to platinum or palladium by the basic nitrogen of NH2 group and have the general structure cis-[M(2,4- DNPH)2Cl2 ].H2O where M = Pt or Pd. The thermal stability of the complexes was followed in the temperature range 25-850 ºC. The antitumor activity of the synthesized compounds has been studied and the compound cis-[Pt(2,4-DNPH)2Cl2 ], was found to display cytotoxicity (IC50 = 4.6 μmol/L) against K562 tumoral cell line. This work is the first to describe the cytotoxic activity of complexes containing 2,4-dinitrophenylhydrazineColegio de Farmacéuticos de la Provincia de Buenos Aire

Análises Mutagênicas de Anuros em Áreas de Mineração de Níquel

Resumo: Biomonitoramento pode ser definido como o uso sistemático das respostas de organismos vivos para avaliar as mudanças ocorridas no ambiente, geralmente causadas por ações antrópicas. Neste artigo foram utilizados anfíbios anuros como bioindicadores da qualidade ambiental e o ensaio do micronúcleo como biomarcador. Esta análise indica a sensibilidade desses organismos frente aos agentes genotóxicos dissolvidos no meio ambiente. Palavras-chave: Micronúcleo. Anfíbios anuros. Bioindicadores. Biomarcadores