Surface micropatterning technique for surface-enhanced Raman scattering analysis

Abstract

A facile and powerful method to form micropatterns, based on nanosphere lithography and layer-by-layer self-assembly, is described in this paper. A monolayer of hexagon close-packed polystyrene (PS) spheres (av 600 nm) was employed as the template. A positively charged polyelectrolyte of poly(diallydimethylammonium) chloride was used as adhesive to absorb oppositely charged spherical Au (av 17 nm) and spherical Ag (av 12 nm), respectively. Both the PS and substrates were coated by colloidal nanoparticles. After removal of the PS template, a micropatterning surface was obtained. Scanning electron microscopy and atomic force microscopy were used to characterize the morphologies. These resulting patterns can be used as good surface-enhanced Raman scattering (SERS) substrates. The enhancement factor is calculated to be 10⁴ ∼ 10⁵. This is a simple and facile technique for surface modification of metal micropatterns with SERS analytical application.