Carbon nanotubes-nanoflake-like SnS2 nanocomposite for direct electrochemistry of glucose oxidase and glucose sensing

Multi-walled carbon nanotubes (MWCNTs)-nanoflake-like SnS2 nanocomposite were designed for immobilization of glucose oxidase (GOx). The direct electrochemistry of GOx and glucose sensing at MWCNTs-SnS2 modified glassy carbon electrode were studied. Compared with single MWCNTs or SnS2, the MWCNTs-SnS2 film has larger surface area and provides a more favorable microenvironment for facilitating the electron transfer between enzyme and electrode surface. The properties of GOx/MWCNTs-SnS2 were examined by scanning electron microscopy, UV-vis spectroscopy, Fourier transform infrared spectroscopy and cyclic voltammetry. The immobilized enzyme on MWCNTs-SnS2 composite film retained its native structure and bioactivity and showed a surface controlled, reversible two-proton and two-electron transfer reaction with a apparent electron transfer rate constant of 3.96 s(-1). The constructed glucose biosensor exhibits wider linear range from 2.0 x 10(-5) M to 1.95 x 10(-3) M, much lower detection limit of 4.0 x 10(-6) M at signal-to-noise of 3 and higher sensitivity of 21.65 mA M-1 cm(-2) than our previous nanoflake-like SnS2-based glucose sensor. The proposed biosensor has excellent selectivity, good reproducibility, and acceptable operational stability and can be successfully applied in the reagentless glucose sensing at -0.43 V. This MWCNTs-SnS2 composite provides a new avenue for immobilizing proteins and fabricating excellent biosensors. (C) 2012 Elsevier B.V. All rights reserved.