Glucose Oxidase Immobilization By Volume Shrinkage Of Graphene Microelectrode And Its Sensing Application

Based on the intrinsic property of volume shrinkage of graphene materials during drying process, the immobilization of glucose oxidase(GOD) was investigated.The main contents are as follows:1. The introduction mainly describes graphene material, enzyme electrodes,immobilization of enzymes, research background and content of the paper.2. Porous active ERGO microeectrode was fabricated, which combined the synergistic advantages of excellent electric conductivity of Pt wire and ERGO, and good biocompatibility of ERGO. Large surface area made the microelectrode have potential application in biosensing. One-step electochemical reduction method was simple, convenient and economical. Moreover, the ERGO microelectrode had three-dimensional(3D) porous hierarchical structure and showed a better electrochemical performance than Pt wire microelectrode.3. Direct electrochemistry of GOD on 3D porous graphene microelectrode has been reported. Based on the 3D interpenetrating porous structure, direct electron transfer between the active sites of GOD and the electrode was achieved, and this was a surfaced-controlled reversible redox process. The amount of electroactive enzyme presented on the electrode surface was 2.83×10-9 mol cm-2, which was higher than the classically modified electrodes. The electron transfer rate constant was 2.98 s-1,showing fast electron transfer. Moreover, the pH window of direct electrochemistry of GOD was wide from 2.69 to 9.09.4. Scanning electron microscope(SEM) and cyclic voltammetry(CV) were adopted to further research the “Door-effect” about five different degrees of GOD immobilization, which was based on the intrinsic property of volume shrinking of ERGO. The state of the door was from fully open to fully close. Regardless of the microelectrode was in which state, direct electrochemistry was always available. The satisfied GOD immobilization was attained when the drying time was 5 minutes. Such immobilization method is simple and easy to operate without any mediator or covering layers. Furthermore, the ERGO microelectrode exhibited relatively satisfactory sensor performance, such as the linear range from 0.05 to 4.2 mM, highsensitivity of 27.66 μA mM-1 cm-2, good anti-interference and stability.