Kinetic and analytical comparison of horseradish peroxidase on bare- and redox-modified single-walled carbon nanotubes
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Author list: Palangsuntikul R., Somasundrum M., Surareungchai W.
Publisher: Elsevier
Publication year: 2010
Journal: Electrochimica Acta (0013-4686)
Volume number: 56
Issue number: 1
Start page: 470
End page: 475
Number of pages: 6
ISSN: 0013-4686
Languages: English-Great Britain (EN-GB)
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Abstract
Single-walled carbon nanotubes (SWNTs) were coated first with methylene blue (MB) by noncovalent adsorption and then by horseradish peroxidase (HRP) by cross-linking with glutaraldehyde. The MB-SWNT/HRP composites formed stable films on glassy carbon electrodes. MB was probably present with a coverage of a monolayer or less. The MB voltammetry was consistent with fast electron transfer to a surface-confined species. The presence of HRP did not significantly affect the MB electrochemistry. MB could mediate electron transfer from HRP in the presence of H 2O 2. Cyclic voltammograms of this process were used to determine the rate constants for the reactions of the native ferriperoxidase with H 2O 2 and of the oxyferryl Compound II with the reduced form of MB. For comparison purposes, the rate constant for the direct electrode reduction of the HRP oxyferryl π-cation radical Compound I was determined in MB-free SWNTs. The results indicate a considerably faster regeneration rate for native ferriperoxidase by the mediated reaction than by direct electrochemistry. Using the MB-SWNT/HRP composites, H 2O 2 could be calibrated by amperometry at -0.3 V vs. SCE. The optimized response (at pH 7.0) had a sensitivity of 661.0 μA mM -1 cm -2 and a limit of detection (3 × S/N) of 0.1 μM. © 2010 Elsevier Ltd.
Keywords
Horseradish peroxidase, Voltammetry
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