Electrochemical behavior and voltammetric determination of dihydronicotinamide adenine dinucleotide using a glassy carbon electrode modified with single-walled carbon nanohorns

We report a simple method for the direct and quantitative determination of dihydronicotinamide adenine dinucleotide (NADH) using a single-walled carbon nanohorn (SWCNH) modified glassy carbon electrode (GCE). The electrochemically activated SWCNH modified GCE (SWCNH/GCE) substantially lowers the overpotential necessary for NADH oxidation compared to the inactivated SWCNH/GCE or bare GCE. We observe a 89-mV shift in the peak potential of NADH from GCE to SWCNH/GCE and another 101-mV shift from inactivated SWCNH/GCE to activated SWCNH/GCE in phosphate buffer (pH 7.0) at a scan rate of 50 mV/s. The activated SWCNH/GCE shows a linear response toward NADH between 1 and 100 mu M with the detection limit of 0.2 mu M. The activated SWCNH/GCE displays good reproducibility, high sensitivity, and excellent stability. Furthermore, the fabricated electrochemical sensors were used to detect NADH in serum by standard addition method and the recoveries are satisfactory.