Silver-nanoparticle-based surface-enhanced Raman scattering wiper for the detection of dye adulteration of medicinal herbs.

By using a silver nanoparticle wiper as a surface-enhanced Raman scattering substrate, a highly sensitive, convenient, and rapid platform for detecting dye adulteration of medicinal herbs was obtained. Commercially available filter paper was functionalized with silver nanoparticles to transform it into the flexible wiper. This device was found to collect dye molecules with unprecedented ease. Experiments were performed to optimize various factors such as the type of wiper used, the wetting reagent, and the wetting/wiping mode and time. Excellent wiper performance was observed in the detection of the simulated adulteration of samples with dyes at various concentrations. The limits of detection for nine dyes, including 10(-6) g/mL for malachite green, 10(-7) g/mL for Rhodamine 6G, and 5 × 10(-8) g/mL for methylene blue, were discerned. The results of this investigation show that this proposed method is potentially highly advantageous for field-based applications. Graphical Abstract Schematic diagram illustrating the fabrication of the paper-based SERS substrate, sample collection process on a herb and SERS examination with the portable Raman spectrometer.