3 Methodology3.1 ChemicalsChemicals will be obtained from Sigma-Aldrich. Graphite powder will be used as raw material. Concentrated hydrochloric acid, sulfuric acid, potassium permanganate and hydrogen peroxide will be used for the oxidation process to oxidize the graphite powder into graphite oxide. The next process will be to obtain the reduced graphene oxide. Hydrazine monohydrate will be used as a reducing agent. To make graphene as a glucose sensor, glucose, chitosan, phosphate buffered saline, potassium chloride, acetic acid, chloroplatinic acid, sulfuric acid, hydrogen peroxide , ascorbic acid and uric acid will be used. All solutions used in the glucose sensor experiment will be prepared with ultra pure water.3.2 Preparation of samples3.2.1 Preparation of graphite oxideGraphite oxide will be synthesized by graphite powder by a process pre-oxidation and oxidation based on the improved method of Hummers and Hummers (Marcano et al., 2010). 20 g of graphite powder will be stirred in a heated solution of 30 ml of H2SO4, 10 g of K2S2O8 and 10 g of P2O5 at 80°C for 30 minutes until a dark blue mixture is formed. The mixture will be cooled to 25°C for 6 hours. After that, deionized water will be added and the ingredient will be filtered and washed until the filtrate becomes pH neutral. Then, the filtrate will be dried overnight in a vacuum desiccator at 25°C. 460 ml of concentrated H2SO4 will be used to oxidize the graphite in the ice bath after the drying process. The KMnO4 will be added slowly with stirring and the temperature of the suspension will be maintained at 20°C. Then, the ice bath will be removed and the suspension will be heated in an oil bath at 35°C for 2 hours until the suspension thickens. and a brownish gray colored effervescence paste will appear...... middle of paper ...... at 3400 cm-1 by FTIR spectra.3.4.3 Cyclic voltammetry (CV) Cyclic voltammetric and amperometric measurements will be carried out to measure and detect the current at the working electrode and plot it against the applied voltage. The electrochemical window of working electrode and electrolyte solution can examine the oxidation/reduction peak of redox species. In the absence of redox analyte, the cyclic voltammogram will form a rectangular shape because the voltage is constantly varying, the current will reach a steady state. GO (0.5 g/mL) will be added to a 0.05 M sodium perborate (PBS) solution. 30 continuous cyclic voltammograms will be performed in the potential range between 0 and -1.5 V with a scan rate of 30 mV/s. A cathodic peak will emerge at -1.0 V with an initial potential of -0.75 V during the first scan of the cathodic potential. The cathodic peak will completely disappear after several cycles.