Amperometric Quantification of NADH Based on Graphene/Methylene Blue Nanocomposite Thin Films on Au(111)

Graphene (Gr)/methylene blue (MB) composites were successfully prepared and amperometric detection of nicotinamide adenine dinucleotide (NADH) was studied on the Gr/MB composite thin films modified Au(111) electrode. Gr sheets were fabricated by using two‐step electrochemical approaches: intercalation of sodium dodecyl sulfate (SDS) into graphite working electrode by electrooxidation and exfoliation of SDS‐intercalated graphite electrode by electrochemical reduction to obtain Gr/SDS suspension. In order to prepare Gr/MB composite structure, first SDS was removed from Gr/SDS suspension and then MB was added into Gr suspension. Gr/MB dispersion was ultrasonicated, vacuum‐filtered through a membrane, and then re‐dispersed into water. Gr/MB nanocomposite was supported on Au(111) substrates by drop‐casting of this composite dispersion. Characterization of Gr/MB composites was carried out by using scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), UV–Visible absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR), and cyclic voltammetry techniques. Gr‐MB/Au(111) electrode, having an excellent electrocatalytic activity, was used for amperometric determination of NADH. The oxidation current density was linearly proportional to NADH concentration in the range between 1.0 to 264 μM. The sensitivity of the sensor was calculated as 0.316 µA µM⁻¹ cm⁻² with a detection limit of 0.3 µM at a signal‐to‐noise ratio of 3.0. POLYM. COMPOS., 38:E118–E127, 2017. © 2016 Society of Plastics Engineers