Aggregation of Ag nanoparticles coated with silica and its SERS effect

In order to realize the unltrasensitive analysis by using the surface enhanced Raman scattering (SERS), we presented a simple and reproducible approach to encapsulate the aggregation of 4-mercaptobenzoic acid-modified Ag nanoparticles with silica. In order to obtain "hot spot", the level of aggregation could be controlled by varying the concentration of NaNO3, and then the aggregation was coated with silica, which was demonstrated with SEM. In conclusion, the SERS signal seriously depended on the level of aggregation. Due to the strong enhancement effect, this technique has the potential in biomedical field.