Synthesis of Ag-MoS2/chitosan nanocomposite and its application for catalytic oxidation of tryptophan

A convenient and low-cost synthesis approach is proposed for the development of a simple and novel electrochemical sensor for the determination of tryptophan (Try). In this synthesis process, graphene-like molybdenum sulfide was successfully obtained, and silver nanoflakes (AgNFs) were directly synthesized on the surface of molybdenum sulfide (MoS2) films, in this process chitosan (CS) and ascorbic acid (AA) acted as the stabilizer and reducing agent, respectively. This nanocomposite was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to evaluate the electrochemical property of Ag-MoS2/CS toward the oxidation of tryptophan. Under the optimized experimental conditions, the oxidation peak currents are proportional to the concentrations of tryptophan over the range of 0.5 μM to 120 μM, and the detection limit is 0.05 μM (S/N = 3). Moreover, the proposed method is free of interference from other amino acid to other coexisting species.