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Influence of solution pH on the electron transport of the self-assembled nanoarrays of single-walled carbon nanotube-cobalt tetra-aminophthalocyanine on gold electrodes: Electrocatalytic detection of epinephrine

Ozoemena, Kenneth I. and Nkosi, Dudu and Pillay, Jeseelan (2008) Influence of solution pH on the electron transport of the self-assembled nanoarrays of single-walled carbon nanotube-cobalt tetra-aminophthalocyanine on gold electrodes: Electrocatalytic detection of epinephrine. ELECTROCHIMICA ACTA, 53 (6). pp. 2844-2851.

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Official URL: http://dx.doi.org/10.1016/j.electacta.2007.10.076

Abstract

This paper provides first evidence of the impact of solution pH on the heterogeneous electron transfer rate constants of self-assembled films of single-walled carbon nanotubes (SWCNT) and SWCNT integrated to cobalt(II)tetra-aminophthalocyanine (SWCNT-CoTAPc) by sequential self-assembly. Using cyclic voltammetry and electrochemical impedance spectroscopy, we proved that both SAMs exhibit notable differences in their response to different buffered solution pH, with and without the presence of redox probe, [Fe(CN)(6)](4-)/[Fe(CN)(6)](3-). Surface pK(a) value for the Au-Cys-SWCNT-CoTAPc was estimated as ca. 7.8, compared to that of the Au-Cys-SWCNT of about 5.5. Interestingly, both redox-active SAMs gave similar analytical response for epinephrine, giving well-resolved square wave voltammograms, with linear concentration range up to 130 mu M, sensitivity of ca. 9.4 x 10(-3) AM(-1), and limit of detection ca. 6 mu M. This analytical result implies that there is no detectable advantage of one of the SAMs over the other in the electrocatalytic detection of this neurotransmitter. (c) 2007 Elsevier Ltd. All rights reserved.

Item Type:Article
Uncontrolled Keywords:cobalt(II)tetra-aminophthalocyanine; single-walled carbon nanotube; self-assembled monolayer; solution pH; electron transfer rates; cyclic voltammetry; impedance spectroscopy; epinephrine detection
Subjects:Material Science > Functional and hybrid materials
Physical Science > Nano objects
Material Science > Nanochemistry
ID Code:525
Deposited By:IoN
Deposited On:20 Jan 2009 12:54
Last Modified:29 Jan 2009 16:14

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