Intense and stable surface-enhanced Raman scattering from Ag@mesoporous SiO2 film

Abstract A surface-enhanced Raman scattering (SERS) film consisting of mesoporous silica (MSiO 2 ) coated Ag nanoparticles (NPs) was achieved. The as-prepared hybrid NPs were uniform in size and formed large amount of aggregates in the film. “Hot spots” were supposed to appear in the MSiO 2 shells with an average size as small as 15 nm. Such a novel core–shell structure therefore induced the enhancement of SERS intensity compared to the film of bare Ag NPs and polymer film of Ag-CMC. The homogeneity and stability of SERS signals from the Ag@MSiO 2 film were also tested. A relative standard deviation of SERS intensity lower than 20% from Raman mapping and a stable SERS signal with excitation power of 100 mW were observed, which were both better than the other two films. Moreover, the obtained Ag@MSiO 2 film was applied to detect thiram pesticides and a detection limit as low as 1×10 −8  M was reached, which indicates the advantages of the Ag@MSiO 2 film in biosensor.