Electrochemical AFM investigation of horseradish peroxidase enzyme electro-immobilization with polypyrrole conducting polymer

In this paper we investigate the nano-characterization of polypyrrole (Ppy) thin film electro-synthesized on highly oriented pyrolitic graphite (HOPG) with and without horseradish peroxidase enzyme (HRP) using Atomic force microscopy (AFM) performed in contact mode and fluid cell with electrolyte and potential control (ECAFM). In situ electro-synthesis of thin polypyrrole film was made by cyclic volt–amperommetry achieving structured Ppy nanoparticles with two types of particle sizes and the same ellipsoidal shape. Furthermore, the electro-immobilization of HRP, onto this film, was made at a fixed potential, achieving different morphology characterized by highly rough, non-homogeneous structure, and partial maintaining of the ellipsoidal particle in specific sites. The effect of polarization time on morphological parameters was studied and two mechanisms of electro-immobilization of HRP with Ppy conducting polymers were proposed.