Laccase on Black Pearl 2000 modified glassy carbon electrode: Characterization of direct electron transfer and biological sensing properties for pyrocatechol

In this paper, it was found that Laccase (Lac) could be stably immobilized on the glassy carbon electrode modified with Black Pearl 2000 (BP2000) and Nafion by a simple technique. The adsorption behavior of Lac immobilized on BP2000 matrix was characterized by environment scanning electron microscope (ESEM), ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR), which demonstrated that BP2000 could facilitate the electron exchange between the active center of Lac and modified electrode. The direct electrochemistry and electrocatalysis behavior of Lac on the modified electrode were characterized by cyclic voltammogram (CV) which indicated that Lac immobilized on the modified electrode displayed a direct, nearly reversible and surface-controlled redox reaction with an enhanced electron-transfer rate constant of 1.940s(-1) at the scan rate of 100 mVs(-1) in 0.1 M phosphate buffer solution (PBS) (pH 7.0). Furthermore, it was also discovered that, in the presence of O-2, Lac immobilized on the modified electrode exhibited the electrocatalytic response to pyrocatechol, and the kinetic apparent Michaelis-constant (K-M(app)) obtained from the Lineweaver-Burk equation was 1.79 mM. The detection limit, linear range and sensitivity of the Lac biosensor were 0.003 mM, 0.003-5.555 mM and 99.84 mu A mM(-1) cm(-2), respectively. (C) 2012 Elsevier Ltd. All rights reserved.