Gold nanoclusters electrodeposited on multi-walled carbon nanotubes: enhanced electrocatalytic activity of hemoglobin
Authors: Zhao, Yue
Fan, Louzhen
Ren, Jingling
Hong, Bo
Journal: Journal of Solid State Electrochemistry (2014)
Discipline: CHEMISTRY
Keywords: 3D Au; electrodeposition; MWCNTs; biocompatibility; electrical transfer

Abstract: Three-dimensional structure domelike gold nanoparticle clusters (3D Au) are electrodeposited onto multi-walled carbon nanotubes (MWCNTs) through improved all-electrochemical three-step method, which involves (1) potential cycling which is performed in order to produce oxide functional groups (carbonyl, hydroxyl, and carboxyl) at the defect sites located at the ends and/or the sidewalls of the MWCNTs, (2) electrochemical oxidation of Au(III) complex to Au(V) complex by using potential-step method, and (3) electrochemical transformation of Au(V) complex to Au nanoparticle clusters on the surface of MWCNTs. This 3D fractal morphology is in marked contrast to the uniform nanoparticle dispersion of MWCNTs, which is achieved when the second step adopts cyclic voltammetry instead of a potential-step method. The 3D Au/MWCNTs-Nafion nanocomposite exhibits enhanced biocompatibility and expedites the electrical transfer from hemoglobin (Hb) to the surface of electrode. The average coverage (Γ) of Hb immobilized on the 3D Au/MWCNTs-Nafion electrode is calculated to be 7.65\u2009×\u200910\u22129&nbsp;mol&nbsp;cm\u22122 and testifies that a larger amount of Hb can access and be entrapped on the electrode surface. The electron transfer rate constant (k S) is calculated to be 1.8&nbsp;s\u22121, which proves that the resulting nanocomposite facilitates Hb’s direct electrochemical behavior. Moreover, the Hb/Au/MWCNTs-Nafion electrode shows prominent electrocatalytic activity and good reversibility for the detection of hydrogen peroxide (H2O2) with a wide linear range from 0.5 to 1,000&nbsp;μmol&nbsp;dm\u22123 and a low detection limit of 0.2&nbsp;μmol&nbsp;dm\u22123. Meanwhile, the Michaelis–Menten constant (K m) is found to be 0.86&nbsp;μmol&nbsp;dm\u22123. These attractive features are attributable to the unique 3D domelike structure of Au nanoparticle clusters on the MWCNTs with much higher electrochemically active surface areas. This provides an efficient platform for the development of mediator-free electrochemical biosensors.

Retracted: No

PubPeer comments:
 Figure 1 of this article and Figure 1 published in Advanced Functional Materials (doi: 10.1002 adfm.200600416) in 2007 have some overlapping regions (with color markings), but they represent different nanoclusters, could the authors check it please? ![file] , 
 Unexpected similarity between fragments of EDX spectra of three different nanoclusters shown in the different papers, could the authors check it please? ![file] , 
 Unexpected similarity between TEM images of two different nanoclusters shown in the different papers, could the authors check it please? ![file] , 
 #1 ![] Fig 1b from [Zhao et al (2007)](10.1007 s00604-006-0701-z) agrees that the lower pair of images depict Pt MWCNTs, in contrast to Au as specified here. ![file] , 
 More sightings. At center right here, Fig 1 from [Zhao et al (2014)] :  TEM images of the 3D Pt MWCNTs obtained by using the potential-step method with pulse widths (s) of (a) 0.0005, (b) 0.001 and (c) 0.01, and (d) the Pt MWCNTs obtained by using CV with 190 cycles. Inserts represented the results of the contact angle measurements. ![file] , 
 #3 ![file] , 
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