The modification of glassy carbon (GC) electrode with deoxyribonucleic acid (DNA) and grapheneis utilized as a new efficient platform for entrapment of methylene blue (MB). Electrochemical andelectroanalytical properties of the modified electrode (DNA/graphene/MB) were investigated by cyclicvoltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry techniques. Cyclicvoltammetric results indicated the excellent electrocatalytic activity of the resulting electrode toward oxidation of β-nicotinamide adenine dinucleotide (NADH) at reduced overpotential (0.1 V vs. Ag/AgCl).It has been found that the DNA/graphene/MB modification has significantly enhanced the effective electrode response toward NADH oxidation. Cyclic voltammetry and rotating disk electrode (RDE) exper-iments indicated that the NADH oxidation reaction involves two electrons and an electrocatalytic rateconstant (kobs) of 1.75 × 106mol-1L s-1. The electrochemical sensor presented better performance in0.1 mol L-1phosphate buffer at pH 7.0. Other experimental parameters, such as the DNA, graphene, MB concentrations and the applied potential were optimized. Under optimized conditions, a linear response range from 10 μmol L-1to 1.50 mmol L-1was obtained with a sensitivity of 12.75 μA L μmol -1. The detection and quantification limits for NADH determination were 1.0 μmol L-1and 3.3 μmol L-1, respectively.© 2013 Elsevier Ltd. All rights reserved.111 543551Li, Z., Huang, Y., Chen, L., Qin, X., Huang, Z., Zhou, Y., Meng, Y., Yao, S., Amperometric biosensor for NADH and ethanol based on electroreduced graphene oxide-polythionine nanocomposite film (2013) Sens. Actuators B, 181, pp. 280-287Creanga, C., El Murr, N., Development of new disposable NADH biosensors based on NADH oxidase (2011) J. Electroanal. 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