Fabrication of ringlike and disclike nano-structures with surface-enhanced Raman scattering activity

Functional gold nanoparticles with tunable surface ligands were used to assemble ringlike and disclike nano-structures. The adjustable formation mechanism was deduced, and important assembling processes happened such as evaporation, cooling, Marangoni flow and drying. With its hydrophobic nature, butanethiol monolayer-protected gold nanoparticles were arranged to form ringlike nano-assemblies. Well-defined disclike nano-structures were obtained as a result of the change of hydrophilic-hydrophobic property and the aggregation of carboxyl group functionalized gold nanoparticles induced by tris(2-aminoethyl)amine. Surface-enhanced Raman spectroscopy (SERS) activities of nano-assemblies were examined. These nano-assemblies showed strong SERS enhancement occurred with the increase of localized surface plasmon resonance. The efficient technique will open a new avenue for fabricating organized nanoparticle structures in a convenient manner. It may be potentially applied for the biosensor due to SERS activities of those structures.