A Research On Glucose Biosensor Based On Graphene/Iron Oxide Enzyme Electrode

Diabetes mellitus,which characterized by high blood sugar,is a metabolic disease caused by insulin secretion defection or insulin resistance in cells.With the increase of the number of people diagnosed with diabetes in recent years,the early diagnosis of diabetes mellitus is of great significance.The glucose biosensor can detect the glucose concentration in the solution system and can be used for rapid and accurate diagnosis of glucose.The research on glucose biosensors is of great concern to researchers.New materials are the driving force of the development of biosensors.Since graphene has been applied on constructing electrochemical biosensors for the first time in 2008,its rapid electron transfer capability has been proved to promote the redox process between glucose oxidase and the surface of the sensor electrode.The development of biosensor electrodes modified by graphene and its composites has become a hotspot.In the application of graphene biosensor such as graphene-nano gold based glucose biosensor has the disadvantages of poor biocompatibility,low limit range,complicated process and high cost.In view of these problems,this paper has carried out a redox method to prepare graphene-iron oxide nanocomposite and its application in glucose sensor.The main contents of the paper are as follows:?1?The graphene oxide was synthesized by the modified Hummers method,and the graphene-iron oxide composites were prepared by in situ deposition of iron oxide particles on the surface of graphene oxide through a self-redox reaction.The results show that Fe₃O₄ particles have been uniformly embedded on rGO sheets and the XRD patterns of the rGO/Fe₃O₄ composite prepared by graphene oxide and ferrous chloride in the weight ratio of 1:20 have a stable diffraction peak.The composite has a wide distribution of particle sizes in the range of 50 nm to 100 nm.The electrochemical performances of graphene-iron oxide on H₂O₂ were studied by electrochemical analysis.The results show that graphene-iron oxide nanocomposite can effectively reduce the impedance of the working electrode and improve the electrochemical properties of the working electrode.The graphene-iron oxide modified glassy carbon electrode?GCE?has good electrical catalytic properties for H₂O₂.?2?rGO/Fe₃O₄/GOx/GCE was prepared by modifying the electrode with graphene-iron oxide nanocomposite and then immobilizing the glucose oxidase?GOx?on the as-fabricated electrode.The direct electron transfer?DET?of glucose oxidase was studied by cyclic voltammetric test of rGO/Fe₃O₄/GOx/GCE in N₂ saturated PBS.The results exhibited that glucose oxidase was immobilized on the graphene-iron oxide modified electrode,and the DET between glucose oxidase and rGO/Fe₃O₄/GOx/GCE was achieved.The apparent DET rate constant?ks?is 2.03 s-1.The results of the test showed that the prepared glucose biosensor had a sensitivity of 2.645 ?A·mM-1 and a detection limit of 106.5 ?M.The amperometric currents increased with the increase of the glucose concentration and calibration curve corresponding to amperometric response was linear against the glucose concentration range from 0.5 to 10 mM,which could be fitted into the equation: I??A?= 2.645 [glucose]?mM?–42.17??A?and R2 = 0.988.The anti-interference and stability test of the glucose biosensor demonstrated an excellent anti-interference ability and stability of the biosensor.