Tungsten Disulfide Nano-Flowers/Silver Nanoparticles Composites Based Electrochemical Sensor for Theophylline Determination

Tungsten disulfide (WS2) nano-flowers/silver nanoparticles (Ag NPs) composites modified glassy carbon electrode (GCE) was prepared by a simple procedure and then successfully used to determine theophylline (TP). In this synthesis process, Ag NPs were directly synthesized on the surface of WS2 nano-flowers. The composites were characterized by scanning electron microscopy (SEM) images, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical oxidation of theophylline was studied by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Compared with the bare GCE and WS2/GCE, the WS2 nano-flowers/Ag NPs composites/GCE could effectively improve the oxidation of theophylline, due to its high surface area and excellent electric conductivity property. Under the optimized experimental conditions, the electrochemical sensor exhibited wide linear range of 0.05 to 150 μM with detection limit of 3 nM (S/N = 3). Furthermore, the sensor showed high sensitivity, good selectivity, good reproducibility and long-term stability to theophylline detection. At the same time, the fabricated electrode was successfully applied for the determination of theophylline in tea samples and pharmaceutical tablets with satisfying results. These results demonstrated that WS2 nano-flowers/Ag NPs composites were promising substrate for the development of high-performance electrochemical biosensor.