Preparation And Application Of Graphene Based Electrochemical Sensors

In this thesis, graphene was modified on the surface of substrate electrodes. Then we studied the application of graphene in electrochemical sensing. The biomolecules such as catalase, hemoglobin, were adsorbed on graphene modified electrode surface and their electrochemical characteristics were also investigated. NO electrochemical sensor and the redox protein/graphene modified electrodes were constructed. Thus, bio-sensing of a number of biological molecules such as hydrogen peroxide, glucose were achieved.The thesis consisted of four chapters: (1) First, the structure, properties, preparation methods and applications of graphene are introduced. The classification and development of electrochemical sensors had been described. Then, the research proposal for this thesis was presented. (2) Graphene modified electrode was prepared through electrochemically reducing graphene oxide on the surface of glassy carbon electrode. The modified electrode owns strong catalytic activity towards the oxidation of nitric oxide. The linear range is from 7.2×10^-7 to 7.84×10^-5mol/L,with a limit of detection of 2.0×10^-7mol/L.With further modification of Nafion, the determination is free from the interference of nitrite. (3) Catalase was adsorbed onto the surface of Cs-GR modified electrode by immersing the Cs-GR modified electrode in catalase's PBS solution. Then the direct electron transfer between catalase and electrode was observed, and bioelectrocatalysis of catalase for H₂O₂ and glucose were investigated. Experimental results show that the linear range of H2O2 is 1-39μM with a detection limt of 0.2μM, and the glucose is from 2.0×10^-6 to 2.06×10^-4 mol/L with a limit detection of 2.7μM. (4) Hb/Cs-GR electrode was fabricated, then the direct electron transfer of Hb and its bioelectrocatalysis to NO was studied.