Controlled growth of metal nanoparticles on amino-functionalized polystyrene microspheres and their application in surface-enhanced Raman spectroscopy

This report describes the fabrication and application of the polystyrene (PS) core/metal (gold and silver) shell composites. The PS core microspheres were functionalized with terminal amino groups which endowed the PS microspheres with positively charged surface, and then seeded with negatively charged gold nanoparticles (NPs) via electrostatic force. The gold-seeded PS microspheres were coated completely with gold (silver) shell via reduction of the appropriate metal ions. The morphology of gold (silver) shell composed of numerous close-packed gold (silver) NPs could be tailored easily by altering amounts of metallic precursor. The as-prepared PS core/metal shell composites can be used as substrates for surface-enhanced Raman spectroscopy (SERS). They exhibited excellent surface enhancement ability when 4-aminothiophenol (4-ATP) was used as a molecule probe.