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Sensors 2005, 5(4), 220-234; doi:10.3390/s5040220
Article

Direct Electrochemistry of Redox Proteins and Enzymes Promoted by Carbon Nanotubes

, ,  and *
Department of Chemistry, Nanjing Normal University, Nanjing 210097, China
* Author to whom correspondence should be addressed.
Received: 5 June 2004 / Accepted: 11 September 2004 / Published: 27 April 2005
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
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Abstract

The redox protein and enzyme, such as hemoglobin (Hb), horseradish peroxidase(HRP) and glucose oxidase (GOx), was immobilized on the surface of the carbon nanotubemodified glassy carbon (CNT/GC) electrode, respectively. The cyclic voltammetric resultsindicated that the redox protein and enzyme underwent effective and stable direct electrontransfer reaction with a pair of nearly symmetrical redox peaks. The formal redox potential,E0’, was almost independent on the scan rates, the average value of E0’ for Hb, HRP andGOx was –0.343 ± 0.001, –0.319 ± 0.002 and –0.456 ± 0.0008 V (vs. SCE,pH 6.9),respectively. The dependence of E0’ on the pH solution indicated that the direct electrontransfer of Hb and HRP was a one-electron-transfer reaction process coupled with oneproton-transfer, while the GOx was a two-electron-transfer coupled with two-protontransfer.The apparent heterogeneous electron transfer rate constant (ks) was 1.25 ± 0.25,2.07 ± 0.69 and 1.74 ± 0.42 s-1 for Hb, HRP and GOx, respectively. The method presentedhere can be easily extended to immobilize other redox enzymes or proteins and obtain theirdirect electrochemistry.
Keywords: carbon nanotube; direct electrochemistry; hemoglobin; horseradish peroxidase; glucose oxidase carbon nanotube; direct electrochemistry; hemoglobin; horseradish peroxidase; glucose oxidase
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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Yin, Y.; Lü, Y.; Wu, P.; Cai, C. Direct Electrochemistry of Redox Proteins and Enzymes Promoted by Carbon Nanotubes. Sensors 2005, 5, 220-234.

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