Silver nanoparticle-doped polyvinyl alcohol coating as a medium for surface-enhanced Raman scattering analysis

A simple polymer substrate for inducing Surface-Enhanced Raman Scattering (SERS) has been investigated. This SERS substrate consists of a solid support, such as a glass slide covered with polyvinyl alcohol (PVA) impregnated with fine silver nanoparticles. The preparation simply involves mixing aqueous PVA polymer with solid AgNO3 to produce a solution that can be easily spin coated on the glass substrate and dried to obtain a hard translucent coating. Aqueous solution of FeSO4.7H2O was used to reduce Ag+ ions to silver nanoparticles. The effects of various experimental conditions of sample preparation were investigated in order to improve the Raman enhancement efficiency of the substrate. The overall substrate performance was evaluated with the use of biologically important compounds: benzoic acid, p-amino benzoic acid, pyridine and dopamine. The spectral features of these compounds closely matched with those reported in literature. The use of the polymer matrix made the SERS substrate resistant to scratching, therefore, improving it to be more suitable for field applications. The hydrophilic nature of the polymer provides additional advantages for probing biological samples. The shelf-life of the dried, unreduced substrates is at least one month.