Novel fabrication of au nanoparticle films on planar and curved surfaces of glass and fiber materials.

We have discovered that poly(ethylenimine)-capped Au nanoparticles can be fabricated into a two-dimensional film by adding toluene into the colloidal solution. The Au nanoparticle film layer creeps up the glass wall of the vial after adding benzenethiol into the toluene phase, thus allowing for a robust Au film to form, not only on the planar and curved surfaces of glasses but also on the inside surfaces of capillaries. First, by depositing onto planar glasses, we demonstrate that the Au films are highly surface-enhanced-Raman-scattering (SERS)-active. Second, by depositing Au nanoparticles onto the inside surface of a glass capillary, we demonstrate that benzenethiol molecules present on Au nanoparticles can be easily desorbed by borohydride, maintaining the initial SERS activity. The Au-coated capillary would then be used, for instance, to investigate the relative adsorption strength of diverse organics in situ by SERS. Third, we demonstrate that Au nanoparticle films can be formed even on the surfaces of dielectric beads and flexible fabrics.