Showing papers by "Ana Maria Oliveira Brett published in 1997"

Voltammetric Behavior of Nitroimidazoles at a DNA-Biosensor

Abstract: The newly developed DNA-biosensor is a very promising tool for the investigation and study of the action of drugs specifically designed to interact with DNA. In this work the electrochemical reduction of nitroimidazole drugs was studied in the presence of DNA immobilized onto the surface of a glassy carbon electrode. This enabled preconcentration of the drug onto the electrode surface, which was then electrochemically reduced to the corresponding hydroxylamine which followed by reoxidation give the nitroso compound and subsequently an azoxycompound. Moreover, as the target of the nitroimidazole action was the DNA, the damage caused to DNA on the electrode surface by a reduction product of this drug could be detected in situ.

Comparison of the Voltammetric Behavior of Metronidazole at a DNA-Modified Glassy Carbon Electrode, a Mercury Thin Film Electrode and a Glassy Carbon Electrode

Abstract: The electroanalytical performance at three electrodes: DNA-modified glassy carbon electrode, mercury thin film electrode and glassy carhon electrode, for the study of the electrochemical reduction of metronidazole is compared. All three electrodes showed a similar trend in the reduction mechanism for metronidazole, dependent on pH in the acid and neutral region and independent in alkaline media, although there was a shift in the peak potentials to more negative values when a bare glassy carhon electrode was used compared to the other two. Besides the advantage of using a solid electrode for the reduction of metronidazole, the DNA-modified glassy carbon electrode enables a lower detection limit of l.0pM owing to the preconcentration of the drug on the electrode surface, which is not the case for the mercury thin film or bare glassy carhon electrodes.

Thin-film gold electrodes produced by magnetron sputtering. Voltammetric characteristics and application in batch injection analysis with amperometric detection

Abstract: Thin-film gold electrodes were produced by radio-frequency sputtering using a polyvinyl chloride foil as substrate. The voltammetric behavior was characterized in various electrolyte solutions. In alkaline and neutral aqueous solutions reliable voltammetric measurements can be performed while in acidic media some nondefined phenomena occur. A novel type of electrode for batch injection analysis (BIA) is presented which is produced from circular pieces of the thin-film material. This electrode can be used for BIA in conventional voltammetric cells. Pulsed amperometric detection is demonstrated to be viable with thin-film gold electrodes and shows analytical advantages over constant-potential detection in the BIA of hydrogen peroxide.