A novel hydrogen peroxide biosensor based on enzymatically induced deposition of polyaniline on the functionalized graphene–carbon nanotube hybrid materials

A novel hydrogen peroxide (H2O2) biosensor based on horseradish peroxidase (HRP) induced deposition of polyaniline (PANI) on the designed graphene–carbon nanotube–nafion/gold–platinum alloy nanoparticles (GE–CNT–Nafion/AuPt NPs) modified glassy carbon electrode was described and its electrochemical behaviors were investigated. UV–visible and Fourier-transform infrared spectra of the resulting HRP/GE–CNT–Nafion/AuPt NPs composite films suggested that the immobilized HRP retained its original structure. Electrochemical impedance spectroscopy and scanning electron microscopy images of the sensor confirmed the formation of PANI by enzyme catalytic deposition in the presence of aniline/H2O2 and HRP. Cyclic voltammograms of PANI at PANI/HRP/GE–CNT–Nafion/AuPt NPs modified glassy carbon electrode showed a pair of well-defined redox peaks of PANI in 0.1 M HAc–NaAc solution (pH 4.3). The reduction peak currents of PANI measured by square wave voltammetry were linearly related to H2O2 concentration in a wider linearity range from 5.0 × 10−7 to 1.0 × 10−4 M with a correlation coefficient of 0.9955, and the detection limit of 1.7 × 10−7 M (S/N = 3). The sensitivity of the method was 3.7 × 102 μA mM−1. Thus the synergistic effect of GE–CNT hybrid materials, AuPt NPs, and the enzymatically induced deposition of PANI provide a general platform for the design of novel electrochemical biosensors.