Surface-enhanced Raman scattering in ETPTA inverse photonic crystals with gold nanoparticles

We present a substrate design for surface-enhanced Raman scattering by decorating three-dimensional inverse photonic crystals with a small amount of Au nanoparticles. Photonic crystals with different positions of the photonic stop band were fabricated by inverting opal-type templates using photopolymerization of a trimethylolpropane ethoxylate triacrylate (ETPTA) photocurable resin. Then Au nanoparticles were embedded into inverse ETPTA films by multiple infiltration. Using the methylene blue dye as a test compound, we found that the enhancement factor of the Raman signal is strongly dependent on the spectral position of the photonic stop band, reaching a value of about 1-2 × 10⁵ when it coincides with the laser wavelength. The detection limit for methylene blue in solution is of the order of 10^-7 M.