Electrochemical conversion of poly-aniline into a redox polymer in the presence of nordihydroguaiaretic acid

Thin films of poly-aniline (PANI) undergo electrochemical restructuring when subjected to potential cycling in the presence of nordihydroguaiaretic acid (NDGA). As a consequence, the properties of PANI change from those of a conducting polymer to those of a redox polymer. Thus formed composite PANI–NDGA films show redox activity characterized by two new electrochemical couples observed at mid-peak potentials of 0.32 and 0.52 V (vs. Ag/AgCl, 0.5 M H2SO4). The peak currents exhibit a linear dependence on the potential scan rate as expected for surface-confined redox species and the peak potentials shift toward lower potentials with increasing solution pH at a rate of ca. 60 mV/pH unit. The PANI–NDGA composite film was found to electrocatalyze the oxidation of NADH in a nearly neutral (pH 7.4) phosphate buffer.