Self-assembly directed synthesis of Au nanorices induced by polyaniline and their enhanced peroxidase-like catalytic properties

Abstract

The self-assembly of noble metal nanoparticles into new-fashioned one, two and three-dimensional structures is very important due to their superior properties in optics, electrics, catalysis, and chemical sensing compared with individual nanoparticles. Here, we first report a facile one-step approach that allows the fabrication of assembled Au nanorices induced by polyaniline (PANI). During the synthesis, a complex of HAuCl₄-(3-aminopropyl)triethoxysilane (APTES) acts as both a soft template and an oxidant; then the reduction of HAuCl₄ is accompanied by the oxidation of aniline, resulting in the formation of Au nanorices within a PANI matrix. The application of the prepared Au/PANI nanorices as enzyme mimics toward the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) is demonstrated. The resultant Au/PANI nanorices display an enhanced peroxidase-like catalytic activity compared with individual Au nanospheres and PANI nanofibers alone, revealing a synergistic effect between Au and PANI components in the Au/PANI nanorices. The Au/PANI nanorices are also used as efficient surface-enhanced Raman scattering (SERS) substrates for in situ monitoring of the oxidation process of TMB during the peroxidase-like catalytic reaction. On the basis of the SERS technique, a discernible detection level of H₂O₂ as low as 10⁻⁸ M is obtained. We envision that such a system may show more potential applications in biocatalysis, disease diagnosis and environmental monitoring.