Controlled fabrication of nanostructures by assembling Au nanoparticles on functionalized polymeric spheres

Abstract

Abstract Hierarchical organic/inorganic composites have been extensively studied, and considerable efforts have been focused on the assemble behaviors of metal nanoparticles (NPs) on soft templates. In this report, a ternary hierarchical nanostructure was successfully fabricated by assembling Au NPs on polystyrene (PS)/Polydopamine (PDA) hybrid microspheres. The ultrathin PDA coatings were firstly synthesized on PS microspheres by pH-induced polymerization of dopamine. Enough amino and hydroxyl groups from PDA were beneficial for Au NPs assembling on the polymer spheres by means of electrostatic interactions. Finally, the as-prepared PS/PDA microspheres serve as templates to immobilize Au nanoparticles on the surface of the composite spheres to form PS/PDA/Au microspheres with uniform size. The isolated products demonstrated a well-defined core/shell/shell nanostructure without sacrificing the spherical PS morphology. Field emission scanning electron microscopy and transmission electronic microscopy verified these hierarchical structures with the PDA ultrathin film connecting between the inner PS core and the outer Au NPs coating. X-ray diffraction and X-ray photoelectron spectroscopy confirmed the existence of PDA and Au coatings on the surface of the composite particles. This green process for preparation of metal-coated polymer spheres supplies potential applications in biosensors, electronics and medical diagnosis.