The Study Of Electrochemical Biosensor Based On Graphene And Ordered Mesoporous Carbon

The preparation of the graphene modified electrode and ordered mesoporouscarbon (OMC) modified electrode were studied in this paper, and we also studied theelectrocatalytic oxidation of them for certain substances. Graphene has excellentphysical and electrochemical properties, such as a large surface area, highconductivity, excellent electrocatalytic activity and fast electronic transmission rate,so the based graphene electrochemical sensors are rapidly developed; orderedmesoporous carbon has the extremely well-ordered pore structure, high specific porevolume, high specific surface area, and tunable pore diameters in the mesopore range,which make it suitable for applications in catalysis and electrochemical biosensor. Weprepared three modified electrodes through their excellent properties:polythionine/graphene composites modified electrode, thionine/Nafion/graphenecomposites modified electrode, curcumin/OMC composites modified electrode.(1) Electrocatalytic oxidation of NADH on polythionine/graphene compositesmodified electrodes.The glassy carbon electrode (GCE) surface was modified with graphene,Graphene/glassy carbon electrode was obtained. Then thionine was modified on theelectrode surface by electrodepositing to obtain a composite electrodepolythionine/Graphene/GCE composites modified electrode. An importantelectrochemical behavior of NADH on the polythionine(PTH)/graphene/GCE wasstudied by cyclic voltammetry method. By the experiment, a larger electrocatalyticactivity on graphene electrodes was showed under neutral conditions. NADH wasdetected by this composite electrode under conditions of pH7.0, and it could bedetected linearly up to a concentration of4.00×10-6mol·L-1-4.89×10-5mol·L-1withan extremely lower detection limit of6.83×10-7mol·L-1.(2) Electrocatalytic oxidation of NADH on thionine/Nafion/graphene compositesmodified electrodes.A thionine/Nafion/Graphene/GCE composites modified electrode was preparedby ion-exchange procedure. Electrochemical behaviors of the resulting electrode wereinvestigated thoroughly with cyclic voltammetry, and one pair of redox peaks wasclearly visualized. Under a lower operation potential of0.1V in0.1mol·L-1pH7.0phosphate buffered solution (PBS), the lower detection limit would be5.74×10-9 mol·L-1estimated (S/N=3). The feasibility for simultaneous determination of uric acid(UA), dopamine (DA), ascorbic acid (AA) and NADH was detected. They was notinterfered each other in certain concentration. Based on the results, a new NADHsensor was successfully established.(3) Electrocatalytic oxidation of hydrous hydrazine on curcumin/OMC/GCEcomposites modified electrodes.A curcumin/OMC/GCE composites modified electrode was developed as ahydrous hydrazine voltammetric sensor. This sensor displayed a very goodelectrocatalytic activity towards hydrazine electrochemical oxidation. The linear rangeis2.50×10-5mol·L-1-2.00×10-4mol·L-1and the detection limit were determined to be1.39×10-6mol·L-1respectively. This electrocatalytic method was used due to itssimplicity, low cost, high sensitivity and fast response for the detection of hydroushydrazine.