The interaction of water-soluble manganese porphyrins with DNA films and their electrocatalytic properties with hydrazine

Abstract

The electrochemistry of water-soluble manganese porphyrins (Mn(4-TMPyP)) has been studied as an electrochemically-active film on double-stranded deoxyribonucleic acid (dsDNA) modified electrodes in solutions at various pH. An electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ deposition of DNA on gold disk electrodes, and Mn(4-TMPyP) (manganese meso-tetrakis-(N-methyl-4-pyridyl)porphyrin) deposition on DNA film modified electrodes. MnII(4-TMPyP) (the reduced form) is more easily deposited on a DNA film than MnIII(4-TMPyP) (the oxidized form). Electrodeposition of Mn(4-TMPyP) can be performed in strong basic aqueous solutions, and shows two redox couples with electrochemically active voltammograms. The films can also be produced on glassy carbon, platinum, gold, and transparent semiconductor tin (IV) oxide electrodes. The Mn(4-TMPyP)/DNA film was electrocatalytically oxidative for hydrazine, hydroxylamine, and SO32- in a basic aqueous solution through a Mn(IV) species. The electrocatalytic efficiency of MnIV(O)(4-TMPyP) was observed to be greater than (OH)MnIV(O)(4-TMPyP). Electrocatalytic oxidation by a Mn(4-TMPyP) film as a catalyst for hydrazine oxidation is also discussed. This shows a new anodic peak current in the second segment after the positive scan during electrocatalytic oxidation, and is pH dependent. © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.