title: Carbon nanotube mat as mediator-less glucose sensor electrode.
abstract: In this paper, the direct electron transfer of glucose oxidase (GOx) on carbon nanotube (CNT) mat electrode is demonstrated. Because of the electrical conductivity and mechanical strength of CNT mat, it can be used as an electrode as well as a catalyst support. Therefore, the preparation process for the CNT mat based sensor electrode is simpler than that of the conventional CNT dispersed sensor electrodes. GOx was covalently immobilized on the oxidized CNT mat, which is connected to a wire by using silver paste and epoxy glue. Attenuated Total Reflectance Fourier Transform-Infrared (ATR-FTIR) result shows transmittance peaks at 1637 cm(-1) and 1525 cm(-1) which are corresponding to the band I and II of amide. Cyclic voltammetric shows a pair of well-defined redox peaks with the average formal potential of -0.425 V (vs. Ag/AgCl reference electrode) in the phosphate buffered saline solution (1 x PBS, pH 7.4). Calculated electron transfer rate constant and the surface density of GOx were 1.71 s(-1) and (3.27 +/- 0.20) x 10(-13) mol/cm2, respectively. Cyclic voltammograms of GOx-CNT mat in glucose solution show that the immobilized GOx retains its catalytic activity to glucose. The amperometric sensor response showed a linear dependence on the glucose concentration in the range of 0.2 mM to 2.18 mM with a detection sensitivity of 4.05 microA mM(-1) cm(-2). The Michaelis-Menten constant of the immobilized GOx was calculated to be 2.18 mM.
authors.affiliation: Multifunctional Composites Laboratary (18-121), Eng. IV UCLA, 420 Westwood Plaza, Los Angeles, CA 90095, USA.
authors.forename: Jongeun
authors.initials: J
authors.lastname: Ryu
authors.forename: Hansang
authors.initials: H
authors.lastname: Kim
authors.forename: Sangeui
authors.initials: S
authors.lastname: Lee
authors.forename: H Thomas
authors.initials: HT
authors.lastname: Hahn
authors.forename: David
authors.initials: D
authors.lastname: Lashmore
mesh_terms: D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry*; D005947:Glucose / Q000032:analysis*; D005949:Glucose Oxidase / Q000737:chemistry*; D037742:Nanotubes, Carbon; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D004800:Enzymes, Immobilized; D037742:Nanotubes, Carbon; D005949:Glucose Oxidase; D005947:Glucose