TITLE

Direct electrochemistry and bioelectrocatalysis of a class II non-symbiotic plant haemoglobin immobilised on screen-printed carbon electrodes

AUTHOR(S)
Chekin, Fereshteh; Leiva, Nélida; Raoof, Jahan Bakhsh; Gorton, Lo; Bülow, Leif
PUB. DATE
October 2010
SOURCE
Analytical & Bioanalytical Chemistry;Oct2010, Vol. 398 Issue 4, p1643
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
In this study, direct electron transfer (ET) has been achieved between an immobilised non-symbiotic plant haemoglobin class II from Beta vulgaris (nsBvHb2) and three different screen-printed carbon electrodes based on graphite (SPCE), multi-walled carbon nanotubes (MWCNT-SPCE), and single-walled carbon nanotubes (SWCNT-SPCE) without the aid of any electron mediator. The nsBvHb2 modified electrodes were studied with cyclic voltammetry (CV) and also when placed in a wall-jet flow through cell for their electrocatalytic properties for reduction of HO. The immobilised nsBvHb2 displayed a couple of stable and well-defined redox peaks with a formal potential ( E°′) of −33.5 mV (vs. Ag|AgCl|3 M KCl) at pH 7.4. The ET rate constant of nsBvHb2, k, was also determined at the surface of the three types of electrodes in phosphate buffer solution pH 7.4, and was found to be 0.50 s on SPCE, 2.78 s on MWCNT-SPCE and 4.06 s on SWCNT-SPCE, respectively. The average surface coverage of electrochemically active nsBvHb2 immobilised on the SPCEs, MWCNT-SPCEs and SWCNT-SPCEs obtained was 2.85 × 10 mol cm, 4.13 × 10 mol cm and 5.20 × 10 mol cm. During the experiments the immobilised nsBvHb2 was stable and kept its electrochemical and catalytic activities. The nsBvHb2 modified electrodes also displayed an excellent response to the reduction of hydrogen peroxide (HO) with a linear detection range from 1 μM to 1000 μM on the surface of SPCEs, from 0.5 μM to 1000 μM on MWCNT-SPCEs, and from 0.1 μM to 1000 μM on SWCNT-SPCEs. The lower limit of detection was 0.8 μM, 0.4 μM and 0.1 μM at 3σ at the SPCEs, the MWCNT-SPCEs, and the SWCNT-SPCEs, respectively, and the apparent Michaelis-Menten constant, $$ {\hbox{K}}_{\rm{M}}^{\rm{app}} $$, for the HO sensors was estimated to be 0.32 mM , 0.29 mM and 0.27 mM, respectively.
ACCESSION #
53840409

 

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