Polymer-encapsulated gold or silver nanoparticles were synthesized and sterically stabilized by a shell layer of poly(4-vinylpyridine) (P4VP) grafted on SiO2 nanoparticles that acts as a scaffold for the synthesis of hybrid noble metal nanomaterials The grafting P4VP shell was synthesized via surface reversible addition-fragmentation chain transfer (RAFT) polymerization of 4-vinylpyridine (4VP) using SiO2-supported benzyl 9H-carbazole-9-carbodithioate (SiO2-BCBD) as the RAFT agent The covalently tethered P4VP shell can coordinate with various transition metal ions such as Au3+ or Ag+ and therefore stabilize the corresponding Au or Ag nanoparticles reduced in situ by sodium borohydride (NaBH4) or trisodium citrate The SiO2-supported RAFT agent and the Au or Ag nanoparticles embedded in the P4VP shell layer were characterized by UV-vis spectrophotometer, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and surface-enhanced Raman spectroscopy (SERS)