Journal
TALANTA
Volume 82, Issue 4, Pages 1149-1155Publisher
ELSEVIER
DOI: 10.1016/j.talanta.2010.06.025
Keywords
Sol-gel films; Electrochemically assisted deposition; 5-Hydroxytryptophan; Voltammetry; Flow-injection analysis
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Funding
- U.S. National Institutes of Health [R15GM087662-01]
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The oxidation of 5-hydroxytryptophan (5-HTPP) yielded a passivating polymeric film at an indium tin oxide (ITO) electrode. Coating ITO with a nanoscale sol-gel film with a mesoporous structure was shown to change the pathway of the chemical reaction coupled to the electron transfer. The sol-gel film was deposited by an electrochemically assisted process, and the mesoporosity was imparted by including generation-4 poly(amidoamine) dendrimer in the precursor solution. The dendrimer was removed subsequently with an atmospheric oxygen plasma. This electrode remained active during cyclic voltammetry and controlled potential electrolysis of 5-HTPP, which was attributed to dimer, rather than polymer, formation from the oxidation product. Mass spectrometry confirmed this hypothesis. The anodic current was limited by the electron-transfer kinetics. Modification of the so-gel film by inclusion of cobalt hexacyanoferrate, which catalyzes the oxidation, resulted in a diffusion-limited current. Determination of 5-HTPP by flow-injection amperometry had a detection limit of 17 nM. (C) 2010 Elsevier B.V. All rights reserved.
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