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Synthetic oligonucleotides: AFM characterisation and electroanalytical studies
Brett, A. M. Oliveira; Paquim, A.-M. Chiorcea; Diculescu, V.; Oretskaya, T. S.One of the most important steps in designing more sensitive and stable DNA based biosensors is the immobilisation procedure of the nucleic acid probes on the transducer surface, while maintaining their conformational flexibility. MAC Mode AFM images in air demonstrated that the oligonucleotide sequences adsorb spontaneously on the electrode surface, showing the existence of pores in the adsorbed layer that reve...
AFM and electroanalytical studies of synthetic oligonucleotide hybridization
Paquim, A. -M. Chiorcea; Diculescu, V. C.; Oretskaya, T. S.; Brett, A. M. OliveiraThe first and most important step in the development and manufacture of a sensitive DNA-biosensor for hybridization detection is the immobilization procedure of the nucleic acid probe on the transducer surface, maintaining its mobility and conformational flexibility. MAC Mode AFM images were used to demonstrate that oligonucleotide (ODN) molecules adsorb spontaneously at the electrode surface. After adsorption,...
Electrochemical and Spectroscopic Studies of the Oxidation Mechanism of the Her...
Garrido, E. M.; Lima, J. L. F. C.; Delerue-Matos, C.; Borges, F.; Silva, A. M. S.; Piedade, J. A. P.; Brett, A. M. OliveiraElectrochemical oxidation of propanil in deuterated solutions was studied by cyclic, differential pulse, and square wave voltammetry using a glassy carbon microelectrode. The oxidation of propanil in deuterated acid solutions occurs at the nitrogen atom of the amide at a potential of +1.15 V vs Ag/AgCl. It was also found that, under the experimental conditions used, protonation at the oxygen atom of propanil oc...
Detection of the damage caused to DNA by niclosamide using an electrochemical D...
Abreu, F. C.; Goulart, M. O. F.; Brett, A. M. OliveiraNiclosamide is the only commercially available molluscicide recommended by the WHO for large-scale use in schistosomiasis control programs. The electrochemical reduction and oxidation mechanism of niclosamide was studied using cyclic, differential and square wave voltammetry, at a glassy carbon electrode. An indirect procedure for in situ quantification of niclosamide using batch injection analysis with electro...
Voltammetric behavior of benznidazole at a DNA-electrochemical biosensor
La-Scalea, M. A.; Serrano, S. H. P.; Ferreira, E. I.; Brett, A. M. OliveiraBenznidazole is a drug used commonly as a therapeutic agent against Chagas' disease in Brazil. To clarify the cytotoxic action of benznidazole the electrochemical reduction of benznidazole has been investigated using a DNA-electrochemical biosensor, prepared by modification of a glassy carbon electrode with DNA, and the results compared with reduction at a bare glassy carbon electrode. The dependence of peak po...
Electrochemical oxidation of propanil and related N-substituted amides
Garrido, E. M.; Lima, J. L. F. C.; Delerue-Matos, C.; Borges, F.; Silva, A. M. S.; Brett, A. M. OliveiraThe electrochemical behaviour of propanil and related N-substituted amides (acetanilide and N,N-diphenylacetamide) was studied by cyclic and square wave voltammetry using a glassy carbon electrode. Propanil has been found to have chemical stability under the established analytical conditions and showed an oxidation peak at +1.27 V versus Ag/AgCl at pH 7.5. N,N-diphenylacetamide has a higher oxidation potential ...
Electrochemical studies and square wave adsorptive stripping voltammetry of the...
Silva, A. M. S. Roque da; Lima, J. C.; Teles, M. T. Oliva; Brett, A. M. OliveiraThe electrochemical reduction of the antidepressant drug fluoxetine was investigated by cyclic, linear sweep, differential pulse and square wave voltammetry using a hanging mercury drop electrode in alkaline buffer solution in water and in a water/acetonitrile mixed solvent. Cyclic voltammograms in aqueous solution showed very strong adsorption of fluoxetine on the electrode with formation of a compact film. Th...
Electrochemical oxidation of mitoxantrone at a glassy carbon electrode
Brett, A. M. Oliveira; Macedo, T. R. A.; Raimundo, D.; Marques, M. H.; Serrano, S. H. P.Mitoxantrone is an anthracycline used as an antitumour antibiotic for leukaemia and breast cancer treatment, due to its interaction with DNA. However, the molecular mechanism of the antitumour action is not completely understood. Using a glassy carbon electrode the electrochemical oxidation of mitoxantrone was shown to be a complex, pH-dependent, irreversible electrode process involving several metabolites. Com...
Electrochemical behaviour of cytochrome c at electrically heated microelectrodes
Voss, T.; Gründler, P.; Brett, C. M. A.; Brett, A. M. OliveiraThe structural changes in cytochrome c with temperature have been been followed using a recently developed electrically-heated microelectrode sensor. Differential pulse voltammetry was used to perform electrochemical measurements of cytochrome c oxidation at different temperatures at heated bare gold electrodes contained in phosphate-buffered cytochrome c solution at room temperature. The voltammetric response ...
Voltammetric behaviour of mitoxantrone at a DNA-biosensor
Brett, A. M. Oliveira; Macedo, T. R. A.; Raimundo, D.; Marques, M. H.; Serrano, S. H. P.The surface of an electrochemical glassy carbon electrode was modified with a layer of double-stranded DNA (dsDNA) or with double-stranded DNA conditioned in single-stranded DNA (ssDNA) and was used to investigate mitoxantrone-DNA interactions. Differential pulse and square wave voltammetry were applied to develop an electroanalytical procedure for the determination of mitoxantrone and evaluate its interaction ...
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