Exfoliated 2D-MoS2 nanosheets on carbon and gold screen printed electrodes for enzyme-free electrochemical sensing of tyrosine

We demonstrate a simple enzyme-free electrochemical sensor for tyrosine (Tyr) detection, based on the enhanced catalytical activity of two-dimensional molybdenum disulphide nanosheets (2D-MoS2), prepared by liquid phase exfoliation and deposited on commercial screen-printed carbon and gold electrodes (SPE). We first evaluate the electrochemical performances of the sensor by cyclic voltammetry (CV) in phosphate buffer solutions (PBS; pH = 7) as a function of the chemical nature and microscale texture of the working electrode, as well as the operating potential window. Results show that the modified-carbon (2D-MoS2-SPCE) and gold (2D-MoS2-SPAuE) electrodes display various anodic and cathodic peaks, whose potential and intensity depend on the potential window, electrode nature and 2D-MoS2 loading. 2D-MoS2 SPE electrodes are finally tested for voltammetric and amperometric detection of tyrosine. We show that 2D-MoS2-SPCE provide the best results, reaching a maximum sensitivity of 1580 mu A mM(-1) cm(-2) and a limit of detection (LOD) of 0.5 mu M computed at a S/N = 3. The proposed method shows satisfactory results also for the detection of tyrosine in a real food integrator sample. To our best knowledge, this is the first report demonstrating the use of 2D-MoS2 for the electrochemical determination of tyrosine.