One-step fabrication of highly dense gold nanoparticles on polyamide for surface-enhanced Raman scattering

Abstract As a powerful analytical tool, the surface-enhanced Raman scattering (SERS) technique has attracted extensive attention. Rapid and low-cost fabrication of the SERS-active substrates in terms of good uniformity and reproducibility remains a significant challenge. Here we showed one facile strategy to decorate polyamide with high-density gold nanoparticles as the SERS substrates via the chemical deposition technology. The size evolution of the gold nanoparticles on the substrates was systematically analyzed with the reaction time and the amount of HAuCl4 in detail. The optimized substrate presented highly dense and uniform gold nanoparticles, which exhibited outstanding sensitivity with the lowest detectable concentration of 10−11 M rhodamine 6G (R 6G), as well as good reproducibility with the relative standard deviation value low to 9.6%. The SERS-based monitoring of malachite green with the lowest detectable concentration of 10−9 M was subsequently realized using the substrates, demonstrating their promising prospect in the sensitive detection of food and aquaculture. Besides, the finite-different time-domain (FDTD) simulations manifest that the Raman enhancement is mainly attributed to the strong local electrical field generated near the highly dense and uniform gold nanoparticles on the substrate. The simple method and prominent Raman enhancement property could facilitate the applications of the SERS substrates in chemical and biological detection.