Direct electrochemistry of glucose oxidase and glucose biosensing on a hydroxyl fullerenes modified glassy carbon electrode

• Chit/GOD-HFs modified GC electrode displays excellent direct electrochemistry.
• Structure and catalytic function of GOD may be preserved in Chit/GOD-HFs.
• A third generation biosensor for determination of glucose with good sensitivity and selectivity.

Direct electrochemistry of glucose oxidase (GOD) was achieved when GOD-hydroxyl fullerenes (HFs) nano-complex was immobilized on a glassy carbon (GC) electrode and protected with a chitosan (Chit) membrane. The ultraviolet–visible absorption spectrometry (UV–vis), transmission electron microscopy (TEM), and circular dichroism spectropolarimeter (CD) methods were utilized for additional characterization of the GOD, GOD-HFs and Chit/GOD-HFs. Chit/HFs may preserve the secondary structure and catalytic properties of GOD. The cyclic voltammograms (CVs) of the modified GC electrode showed a pair of well-defined quasi-reversible redox peaks with the formal potential (E°′) of 353±2 mV versus Ag/AgCl at a scan rate of 0.05 V/s. The heterogeneous electron transfer constant (ks) was calculated to be 2.7 ± 0.2 s-1. The modified electrode response to glucose was linear in the concentrations ranging from 0.05 to 1.0 mM, with a detection limit of 5±1 μM. The apparent Michaelis–Menten constant (Kmapp) was 694±8 μM. Thus, the modified electrode could be applied as a third generation biosensor for glucose with high sensitivity, selectivity and low detection limit.

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