Synthesis of silver nanoparticle-coated poly(styrene-co-sulfonic acid) hybrid materials and their application in surface-enhanced Raman scattering (SERS) tags

Abstract

A straightforward, mild and green chemistry process had been developed to synthesize well-defined spherical Ag/PS (polystyrene) hybrid materials by using nontoxic L-ascorbic acid as both reducing agent and capping agent. Negatively charged –SO₃⁻ could act as a linker between Ag⁺ ions (Ag nanoparticles) and polystyrene beads. The positively charged PS beads were also prepared by a grafting method, and silver nanoparticles deposition on positively charged and uncharged PS beads were also studied. The Ag nanoparticles were coated on the poly(styrene-co-sulfonic acid) beads via an in situ reduction method. The morphologies of the synthesis samples were investigated by field emission-scanning electron microscopy (FE-SEM), (high resolution) transmission electron microscopy (TEM, HRTEM), X-ray diffraction (XRD), and selected-area electron diffraction (SAED). The results indicated that the reducing agent and electric charge had an important influence on the deposition of silver nanoparticles. As a potential application, the Ag/PS hybrid materials were embedded with the reporter molecule methylene blue (MB), and the signal intensity of the SERS (surface-enhanced Raman scattering) tags could be enormously increased. So, the Ag/PS hybrid SERS tags can provide unique signal averaging for potentially quantitative analysis, which were used for SERS substrate design and SERS bioassays analysis. The facile and green chemistry preparation method might also provide a development direction to fabricate different nanometal/PS composites by the simple procedure.