Encontrados 16 documentos, a visualizar página 1 de 2
Electrochemical determination of the herbicide bentazone using a carbon nanotub...
Rahemi, V.; Garrido, Jorge; Borges, Fernanda; Oliveira-Brett, A. M.; Garrido, E. ManuelaAn electrochemical sensor has been developed for the determination of the herbicide bentazone, based on a GC electrode modified by a combination of multiwalled carbon nanotubes (MWCNT) with b-cyclodextrin (b-CD) incorporated in a polyaniline film. The results indicate that the b-CD/MWCNT modified GC electrode exhibits efficient electrocatalytic oxidation of bentazone with high sensitivity and stability. A cycli...
Electrochemical oxidation of ochratoxin A at a glassy carbon electrode and in s...
Oliveira, S. C. B.; Diculescu, V. C.; Palleschi, G.; Compagnone, D.; Oliveira-Brett, A. M.Ochratoxin A (OTA) is a fungal metabolite that occurs in foods, beverages, animal tissues, human blood and presents carcinogenic, teratogenic and nephrotoxic properties. This study concerns the redox properties of OTA using electrochemical techniques which have the potential for providing insights into the biological redox reactions of this molecule. The in situ evaluation of the OTA interaction with DNA using ...
Electrochemistry of nanoscale DNA surface films on carbon
Oliveira-Brett, A. M.; Paquim, A. M. Chiorcea; Diculescu, V. C.; Piedade, J. A. P.A DNA electrochemical biosensor is an integrated receptor-transducer device. The most important step in the development and manufacture of a sensitive DNA-biosensor for the detection of DNA-drug interactions is the immobilization procedure of the nucleic acid probe on the transducer surface. Magnetic A/C Mode atomic force microscopy (MAC Mode AFM) images in air were used to characterize two different procedures...
Atomic Force Microscopy and Anodic Voltammetry Characterization of a 49-Mer Die...
Chiorcea-Paquim, A. M.; Piedade, J. A. P.; Wombacher, R.; Jäschke, A.; Oliveira-Brett, A. M.Atomic force microscopy and differential pulse voltammetry were used to characterize the interaction of small highly structured ribozymes with two carbon electrode surfaces. The ribozymes spontaneously self-assemble in two-dimensional networks that cover the entire HOPG surface uniformly. The full-length ribozyme was adsorbed to a lesser extent than a truncated RNA sequence, presumably due to the formation of a...
Electrochemical sensing of the behaviour of oligonucleotide lipoplexes at charg...
Piedade, J. A. P.; Mano, M.; Lima, M. C. Pedroso de; Oretskaya, T. S.; Oliveira-Brett, A. M.Complexes between short oligodeoxynucleotides (ODN) with a variable dGxdCy base composition and liposomes composed of the cationic lipid DOTAP (ODN lipoplexes) were studied by differential pulse voltammetry at a glassy carbon electrode. Since lipoplexes are spontaneously formed by electrostatic interactions, the objective of the voltammetric study was to investigate their behaviour at the electrode surface/solu...
Voltammetric determination of all DNA nucleotides
Oliveira-Brett, A. M.; Piedade, J. A. P.; Silva, L. A.; Diculescu, V. C.The voltammetric oxidation of all deoxyribonucleic acid (DNA) monophosphate nucleotides is investigated for the first time over a wide pH range by differential pulse voltammetry with a glassy carbon electrode. Experimental conditions such as the electrode size, supporting electrolyte composition, and pH were optimized to obtain the best peak potential separation and higher currents. This enabled the simultaneou...
Voltammetric behaviour of oligonucleotide lipoplexes adsorbed onto glassy carbo...
Piedade, J. A. P.; Mano, M.; Lima, M. C. Pedroso de; Oretskaya, T. S.; Oliveira-Brett, A. M.The voltammetric behaviour of oligonucleotide lipoplexes (ODN-lipoplexes) prepared from short oligodeoxynucleotides (ODN), with different base compositions, and liposomes of the cationic lipid DOTAP, was studied by differential pulse voltammetry with a glassy carbon mini-electrode. It was found that the ODN base composition influences the ODN-lipoplex voltammetric response. Differential pulse voltammograms for ...
Voltammetric Oxidation of Drugs of Abuse II. Codeine and Metabolites
Garrido, J. M. P. J.; Delerue-Matos, C.; Borges, F.; Macedo, T. R. A.; Oliveira-Brett, A. M.The oxidation of codeine on glassy carbon electrodes has been studied in detail using differential pulse voltammetry. The results obtained using a glassy carbon electrode clearly show a much more complex oxidation mechanism than that previously reported when platinum and gold electrodes were used. To clarify the codeine oxidative profile, several metabolites and analogues of this alkaloid, codeine N-oxide, norc...
Voltammetric Oxidation of Drugs of Abuse I. Morphine and Metabolites
Garrido, J. M. P. J.; Delerue-Matos, C.; Borges, F.; Macedo, T. R. A.; Oliveira-Brett, A. M.A detailed study of the electrochemical oxidative behavior of morphine in aqueous solution is reported. Through the synthesis of several metabolites and derivatives, pseudomorphine, morphine N-oxide, normorphine, dihydromorphine and 2-(N,N-dimethylaminomethyl)morphine, and their voltammetric study it was possible to identify the oxidation peaks for morphine. The anodic waves are related with the oxidation of ph...
Voltammetric Oxidation of Drugs of Abuse III. Heroin and Metabolites
Garrido, J. M. P. J.; Delerue-Matos, C.; Borges, F.; Macedo, T. R. A.; Oliveira-Brett, A. M.The oxidative behavior of heroin in aqueous solution is reported. In order to identify its oxidation peaks, several metabolites, 6-monoacetylmorphine, 3-monoacetylmorphine and norheroin, were synthesized and their electrochemical behavior studied using differential pulse voltammetry. The anodic waves observed for heroin correspond to the oxidation of the tertiary amine group and its follow-up product (secondary...
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