Ultrasensitive and reproducible surface-enhanced Raman scattering detection via an optimized adsorption process and filter-based substrate

Abstract

Wih a view to improve the surface-enhanced Raman scattering (SERS) properties, including the sensitivity and uniformity, a simple and practical pretreatment method via optimizing the adsorption process of probe molecules and the morphology of SERS-active nanostructures was studied. Excellent SERS performances were obtained using this method such as high sensitivity (5 × 10⁻¹⁴ M rhodamine 6G, 1 × 10⁻⁸ M melamine), remarkable uniformity (∼9% relative standard deviation (RSD)) and reproducibility (∼10% RSD). Uniform and repeatable silver nanoparticle arrays were fabricated by an optimized filter-based method, which guaranteed the reliability of SERS detection. The SERS intensity was greatly improved by adjusting the adsorption capacity of the noble metal nanostructures, which has a linear relationship with the pH value of silver solution below 10. An accurate and reliable enhancement factor (EF) of 3.28 × 10⁸ was calculated through the quantification of the adsorbed probe molecules. It is worth noting that the lifetime of the substrates prepared by this method could be prolonged to two months, which was definitely longer than other ordinary silver SERS substrates. The pretreatment method not only provided perfect SERS properties, but also made SERS a practical analysis tool because of its good homogeneity and ultralow detection limit.