Direct Electrochemistry and Electrocatalysis Behaviors of Glucose Oxidase Based on Hyaluronic Acid-Carbon Nanotubes-Ionic Liquid Composite Film

Multi-walled carbon nanotubes (MWNTs) were dispersed in the ionic liquid [BMIM][BF4] to form a uniform black suspension. Based on it, a novel glucose oxidase (GOx)-hyaluronic (HA)-[BMIM][BF4]-MWNTs/GCE modified electrode was fabricated. UV-vis spectroscopy confirmed that GOx immobilized in the composite film retained its native structure. The experimental results of EIS indicated MWNTs, [BMIM][BF4] and HA were successfully immobilized on the surface of GCE and [BMIM][BF4]-MWNTs could obviously improve the diffusion of ferricyanide toward the electrode surface. The experimental results of CV showed that a pair of well-defined and quasi-reversible peaks of GOx at the modified electrode was exhibited, and the redox reaction of GOx at the modified electrode was surface-confined and quasi-reversible electrochemical process. The average surface coverage of GOx and the apparent Michaelis-Menten constant were 8.5x10(-9) mol/cm(2) and 9.8 mmol/L, respectively. The cathodic peak current of GOx and the glucose concentration showed linear relationship in the range from 0.1 to 2.0 mmol/L with a detection limit of 0.03 mmol/L (S/N=3). As a result, the method presented here could be easily extended to immobilize and obtain the direct electrochemistry of other redox enzymes or proteins.