Generalized fabrication of surfactant-stabilized anisotropic metal nanoparticles to amino-functionalized surfaces: application to surface-enhanced Raman spectroscopy.

A universal and facile approach for the self-assembly of surfactant-coated anisotropic metal nanoparticles on the amino-functionalized planar and spherical surfaces based on electrostatic attraction has been explored. Large-scale and different surface coverage of monolayer film and metallodielectric core-shell nanostructures of anisotropic metal nanoparticles, including Au nanorods, Au(core)Ag(shell) nanorods and Ag nanoprisms, have been fabricated. The optical response in the visible and the near infrared (NIR) of resulting nanostructures can be easily controlled by varying the concentration of the anisotropic nanoparticle, the amount of silica particles, and the immersion time of the substrates. Large-scale anisotropic metal nanoparticle monolayer films with subtle control over the surface coverage and tunable plasmon resonance as surface-enhanced Raman spectroscopy (SERS) substrates for probing 4-aminothiophenol were investigated, which exhibited high SERS activity, stability and reproducibility.