Electrochemical synthesis of polyaniline nano-network on α-alanine functionalized glassy carbon electrode and its application for the direct electrochemistry of horse heart cytochrome c

Polyaniline (PAN) nano-particles, nano-fibrils, and nano-network have been synthesized via electrochemical polymerization of aniline using a three-step electrochemical deposition procedure on alpha-alanine (ALA)-monolayer functionalized glassy carbon electrode (GCE). The structure and properties of PAN nano-structures have been characterized using field emission scanning electron microscope (SEM), Fourier transform infrared spectra (FT-IR), and electrochemical techniques. The 3-dimensional (3D) PAN nano-network/ALA composite film coated GCE (PAN-ALA/GCE) leads to the direct electrochemistry of horse heart cytochrome c (Cyt c) immobilized on this electrode surface. The immobilized Cyt c maintains its activity, showing a surface-controlled electrode process with the electron transfer rate constant (k(s)) of 21.9 s(-1) and the charge-transfer coefficient (alpha) of 0.37, and could be used for the electrocatalytic reduction of hydrogen peroxide (H2O2). The steady-state current response increases linearly with H2O2 concentration from 2.5 x 10(-5) to 3.0 x 10(-4) mol 1(-1). The detection limit (3 delta) is 8.2 x 10(-6) mol l(-1). (C) 2008 Elsevier B.V. All rights reserved.