Formation and Electrochemical Characterisation of Enzyme-Assisted Formation of Polypyrrole and Polyaniline Nanocomposites with Embedded Glucose Oxidase and Gold Nanoparticles

Abstract

Enzyme-assisted synthesis of electrochemically active nanocomposite structures based on π-π conjugated polymers polyaniline (PANI) and polypyrrole (Ppy) is reported. The synthesis of both conducting polymers was induced by hydrogen peroxide, which is generated during catalytic action of glucose oxidase (GOx), and this polymerisation was performed in the presence of (i) gold nanoparticles of 6 nm diameter (AuNPs(6nm)) or (ii) tetrachloroauric acid (HAuCl4). Formed nanocomposites were evaluated electrochemically and spectrophotometrically. Field emission scanning electron microscopy results illustrated that nanocomposites are poly-dispersed particles tend to agglomerate during centrifugation. Hydrodynamic diameter evaluated by dynamic light scattering technique for PANI/AuNPs(6nm)&GOx- or PANI/AuNPs(AuCl4 −)&GOx-based nanocomposites after 108 h lasting polymerization was 1.90 or 1.70 times larger than that determined for Ppy/AuNPs(6nm)&GOx or Ppy/AuNPs(AuCl4 −)&GOx, respectively. Oxidation peaks in cyclic voltammograms determined for electrodes modified by PANI/AuNPs(6nm)&GOx-, PANI/AuNPs(AuCl4 −)&GOx- and PANI/GOx-based nanocomposites were observed at +0.332, +0.349, and +0.542 V. For Ppy/AuNPs(6nm)&GOx-, Ppy/AuNPs(AuCl4 −)&GOx- and Ppy/GOx-based nanocomposites oxidation peaks were observed at +0.425, +0.545 and +0.508 V, respectively. Oxidation peaks of PANI nanocomposites without and with AuNPs or AuCl4 - appeared due to the conversion of PANI leucoemeraldine form to emeraldine salt, while for Ppy – are attributed to the transition of cation-polaron into the cation-bipolaron-based state of Ppy.