Optimization of extinction efficiency of gold-coated polystyrene bead substrates improves surface-enhanced Raman scattering effects by post-growth microwave heating treatment

Abstract

We report a novel post-growth microwave treatment approach to selectively modify the surface morphologies of gold (Au) films coated on the polystyrene (PS) bead substrates for effectively improving the surface-enhanced Raman scattering (SERS) effect on the analytes. The discrete dipole approximation (DDA) model was introduced to evaluate the enhancement effects by calculating the localized electromagnetic field distribution and extinction efficiency based on the sizes of the trenches and voids, and the surface roughness of the modified Au-PS bead substrates. The SERS performance of microwave-modified Au-PS substrates on rhodamine 6G (Rh 6G) and saliva yields at least 10-fold improvements in SERS intensities compared to the as-grown substrates, which is also in agreement with theoretical predictions by DDA modeling. This work demonstrates both experimentally and theoretically the efficacy of the microwave heating treatment on modifying the Au-PS bead substrates for the realization of high SERS performance in biomedical applications. © 2009 John Wiley & Sons, Ltd.