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Please use this identifier to cite or link to this item: http://hdl.handle.net/10651/33260

Title: 5-hydroxytryptophan (5-HTPP) as a precursor of a catalyst for the oxidation of NADH
Author(s): Santos Álvarez, Noemí de los
Lobo Castañón, María Jesús
Miranda Ordieres, Arturo José
Tuñón Blanco, Paulino
Abruña, Héctor
Issue date: 2005
Publisher: American Chimica Society
Publisher version: http://dx.doi.org/10.1021/ac048554y
Citation: Analytical Chemistry, 77(8), p. 2624-2631 (2005); doi:10.1021/ac048554y
Format extent: pp. 2624-2631
Abstract: Following oxidation of 5-hydroxytryptophan (5-HTPP) at a pyrolytic graphite electrode at pH 7.5, two quasi-reversible redox couples emerge at −0.170 and +0.032 V, respectively, due to oxidation products strongly adsorbed to the electrode surface.These redox processes have been electrochemically and kinetically characterized in terms of the dependence of the formal potential (E°‘) with pH, variation of the current density with scan rate, operational stability, and electron-transfer rate constant (ks). The wave centered at +0.032 V could mediate the oxidation of NADH, exhibiting a strong and persistent electrocatalytic response. A quinone-imine structure has been proposed as the electrocatalytically active species. The kinetics of the reaction between the mediator and NADH has been characterized via rotating disk electrode voltammetry, and it has been found that the rate constant for the reaction is dependent on the solution concentration of NADH. 5-HTPP modified electrodes could be employed in the amperometric detection of NADH with a limit of detection in the nanomolar range. Moreover, 5-HTPP modified electrodes retain their electrocatalytic activity for at least one week. The potential application of these electrodes to amperometric biosensor is demonstrated.
URI: http://hdl.handle.net/10651/33260
ISSN: 0003-2700
Sponsored: N.S.-A.thanks the Ministerio de Educación, Cultura y Deportes (Spain) for FPU grant.
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