A probe for NADH and H2O2 amperometric detection at low applied potential for oxidase and dehydrogenase based...

Modified screen-printed electrodes for amperometric detection of H(2)O(2) and nicotinamide adenine dinucleotide (NADH) at low applied potential are presented in this paper. The sensors are obtained by modifying the working electrode surface with Prussian Blue, a well known electrochemical mediator for H(2)O(2) reduction. The coupling of this sensor with phenazine methosulfate (PMS) in the working solution gives the possibility of measuring both NAD(P)H and H(2)O(2). PMS reacts with NADH producing PMSH, which in the presence of oxygen, gives an equimolar amount of H(2)O(2). This allows the measurement of both analytes with similar sensitivity (357 mA mol(-1)L cm(-2) for H(2)O(2) and 336 mA mol(-1)L cm(-2) for NADH) and LOD (5x10(-7)mol L(-1) for H(2)O(2) and NADH) and opens the possibility of a whole series of biosensor applications. In this paper, results obtained with a variety of dehydrogenase enzymes (alcohol, malic, lactate, glucose, glycerol and glutamate) for the detection of enzymatic substrates or enzymatic activity are presented demonstrating the suitability of the proposed method for future biosensor applications.