Fabrication of hydrogels with nanoparticles as surface-enhanced Raman scattered (SERS) substrates and their application in Raman imaging

A polyvinyl alcohol-silver nanoparticle (PVA-Ag NP) hydrogel was fabricated using a simple and facile method; it was used as a substrate for surface-enhanced Raman scattering (SERS). The Ag+ ions dispersed uniformly in the PVA network were reduced by NaBH4; this process was termed dipping method. Compared with conventional SERS substrates (e.g., colloidal suspensions), the prepared PVA-Ag NP hydrogel has prominent Raman enhancement effects for crystal violet (CV), and the detection limit was 10−12 M. It could also help detect rhodamine B, methylene blue, and 4-mercaptobenzoic acid. In addition to SERS, the reliable 3D porous structure was utilized in the Raman imaging of CV at 1621 cm−1 in a nude mouse.