▎ 摘　　要

An amperometric urea biosensor was fabricated using Indium tin oxide (ITO) coated Polydiphenylamine (PDPA)/Phosphotungstic acid (PTA)/Graphene (Gra) hybrid nanocomposites modified electrode (ITO/PDPA/PTA/Gra-ME) by an electrochemical-deposition technique. Scanning Electron Microscopy (SEM) and Atomic Force microscopy (AFM) techniques were used to capture the surface morphology and surface coating thickness of nanocomposite sandwiched electrodes. Electro-catalytic performances of modified hybrid electrodes were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) techniques. ITO/PDPA/PTA/Gra-ME exhibits a good linear response to urea concentration over the range of 1-13 mu M along with a correlation coefficient of 0.999, good sensitivity (1.085 mu A/mu M cm(2)) and at a low response time (5 s). The enhanced electro-catalytic activity of ITO/PDPA/PTA/Gra-sandwich towards urea was owing to the synergistic contribution of tungsten atoms (phosphotungstic acid anion), diphenoquinone diamine (DPDI2+) form of PDPA/Graphene that enhances the fast electron transfer rate. Also, interfering analytes were studied to ensure the fabricated sensor is best suitable for practical applications.