Preparation And Application Of Electrochemical Sensor Based On Graphene

Graphene is a two-dimensional sheet of sp2 hybridized carbon. Its high conductivity and a small band gap facilitate the conduction of electrons between the biomolecules and the graphene surface.The unique electronic properties of graphene make it an enticing sensor, catalysis and energy material in different areas. Graphene becomes the most widely used nanomaterial of the 21st century for a plethora of diversified applications. The main works are described as follows:1. The graphene oxide (GNO) was prepared from purified flake graphite by modified Hummers method. The graphene (GN) film was obtained via one-step electro-deposition of graphene oxide on the surface of a glassy carbon electrode (GCE) by means of Cyclic Voltammetry (CV) in 0.01 mol/L KN03. The molecular structure, surface morphology and electrochemical properties of GN were determined by Scanning Electron Microscope (SEM) and electrochemical techniques. The Electrochemical behaviors of Guanine (Gua) at GN modified glassy carbon electrode were investigated by CV and Linear Sweep Stripping Voltammetry (SLSV) in HAc-NaAc PH=5.0. The results show that the charge transfer resistance of [Fe(CN)6] 3/4- at GN/GCE is lower as compared to that of the bare glass carbon electrode, indicating that GN can greatly reduce the electrode charge transfer resistance Meanwhile, the results of SLSV demonstrate that the oxidation peak current of Gua at GN/GCE increased 3.2 times than that observed on the unmodified glassy carbon surface in HAc-NaAc (PH=5.0), the electrooxidation of guanine on GN/GCE was a two-electron and two-proton process. Electrode reaction mechanism and optimized conditions are also discussed in this paper.2. The novel electrochemical sensor based on Fe3O4-graphene nanoparticles and β-Cyclodextrins modified glassy carbon electrode was constructed and presented an excellent electrocatalytic activity towards the oxidation of Hypoxanthine. The results show that linear range for determination of Hypoxanthine ranges from 0.1 to 10 μmol/L with the very easy preparation, surface regeneration and the reproducibility of the voltammetric respons. A simple, sensitive, stability and rapid determination of Hypoxanthine was established with a detection limit of 0.01μmol/L. The proposed method is used for the determination of Hypoxanthine and xanthine in the pork with satisfactory results.3. An electrochemical sensor of uric acid was developed using the modified electrode with graphene via casting and poly-L-lysine by cyclic voltammetry. The developed sensor could catalyze the oxidation reaction of uric acid. Under the optimized conditions, the electrochemical response was portional to the concentrations of uric acid from 0.1 to 10 μmol/L with the detection limit of 0.01 μmol/L based on a signal-to-noise ratio to 3 (S/N=3). The proposed method is used for the determination of uric acid in the urine samples with satisfactory results.