A silver nanoparticle embedded hydrogel as a substrate for surface contamination analysis by surface-enhanced Raman scattering

A surface enhanced Raman scattering (SERS) substrate, capable of extracting small amounts of organic species from surfaces of different types of materials with variable roughness, has been fabricated. The substrate consists of Ag NPs encapsulated in poly(vinyl alcohol) (PVA) hydrogels, commonly known as PVA “slime”. Unlike traditional SERS substrates, such as colloidal suspensions, the resulting PVA slime SERS substrate presents good viscoelasticity, allowing it to conform to the surface of various materials of arbitrary roughness. Surfaces of different materials, including sandpapers, cotton, metal, and wood, previously contaminated with nile blue A (NBA) were analyzed with the PVA slime SERS substrate. Limits of detection (LOD) as low as 100 ppb (0.79 ng in a total amount on an area of ∼3 cm2) were achieved for all surfaces tested. Pesticides and Sudan red III on the glass surface have also been detected, with a LOD of 1.6 ng per ∼3 cm2.