Three-Dimensionally Microporous Polypyrrole Film as an Efficient Matrix for Enzyme Immobilization

The development of new porous materials has opened unprecedented opportunities for a wide range of applications. In the present work, a three-dimensionally interconnected porous polypyrrole structure was proposed for biosensing. Silica nanoparticles with good monodispersion and uniformity of the spheres synthesized by improved Stober methods was used as template for porous polypyrrole electrodeposition. Voltammetric and electrochemical impedance measurements showed that the polypyrrole 3D-network arrays provided excellent matrices for the immobilization of horseradish peroxidase. The immobilized horseradish peroxidase on these polypyrrole 3D-network arrays retained its bioactivity effectively and displayed a pair of redox peaks with a formal potential of -0.275 V and an excellent electrocatalytic response toward the reduction of hydrogen peroxide (H2O2). This allowed the detection of H2O2 concentration with a linear range from 1 mu M to 7.94 mu M. The detection limit was found to be 0.22 mu M at a signal-to-noise ratio of 3. This method provided an alternative way for the biosensor construction.