Filter paper loaded with gold nanoparticles as flexible SERS substrates for sensing applications.

Surface-Enhanced Raman Scattering (SERS) performance of filter paper (FP) loaded with gold nanoparticles (Au NPs) of three different size/shapes (spherical, triangular and star) were investigated. Spherical Au NPs were synthesized using femtosecond laser ablation of Au target in distilled water and other two anisotropic (triangular and star-shaped) Au NPs were prepared by colloidal chemical methods. COMSOL Multiphysics simulations were performed to investigate near field distributions of these Au NPs and as expected, the strongly enhanced near-field intensity at the sharp features was observed. The SERS performance [using the dye molecule Nile Blue (NB)] of star-shaped Au NPs loaded FP was superior compared to the triangle and spherical Au NPs loaded FP due to the presence of sharp tips and thus it was proved to be capable of detecting 10 pM NB concentration with an estimated enhancement factor of ∼3.7×1010. [ABSTRACT FROM AUTHOR]