Nanoflake-like SnS2 matrix for glucose biosensing based on direct electrochemistry of glucose oxidase

A novel biosensor is developed based on immobilization of proteins on nanoflake-like SnS2 modified glass carbon electrode (GCE). With glucose oxidase (GOD) as a model, direct electrochemistry of the GOD/nanoflake-like SnS2 is studied. The prepared SnS2 has large surface area and can offer favorable microenvironment for facilitating the electron transfer between protein and electrode surface. The properties of GOD/SnS2 are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and cyclic voltammetry (CV), respectively. The immobilized enzyme on nanoflake-like SnS2 retains its native structure and bioactivity and exhibits a surface-controlled, reversible two-proton and two-electron transfer reaction with the apparent electron transfer rate constant (ks) of 3.68 s−1. The proposed biosensor shows fast amperometric response (8 s) to glucose with a wide linear range from 2.5 × 10−5 M to 1.1 × 10−3 M, a low detection limit of 1.0 × 10−5 M at signal-to-noise of 3 and good sensitivity (7.6 ± 0.5 mA M−1 cm−2). The resulting biosensor has acceptable operational stability, good reproducibility and excellent selectivity and can be successfully applied in the reagentless glucose sensing at −0.45 V. It should be worthwhile noting that it opens a new avenue for fabricating excellent electrochemical biosensor.