Aniline was served as reductant in this paper for the synthesis of gold nanoparticles with positively charged coatings by one pot reaction. Transmission electron microscopy (TEM) was used to visualize the shell structure around the gold nanoparticle cores. Fluorescence spectroscopy and X-ray photoelectron spectroscopy (XPS) proved that the shell was polyaniline or its aniline oligomer which was positively charged in the emeraldine salt form. The synthesized nanoparticles can be assembled onto gold electrode surface through negatively charged submonolayer of 3-mercapto propanoic acid. Improved performance for direct electron transfer of superoxide dismutase on such assemblies can be achieved.

Key words: gold nanoparticle, conductive polymer, aniline, superoxide dismutase, direct electrochemistry