Langmuir-Blodgett Film of Esterifiable Silica Nanoparticles as Substrates for Surface-Enhanced Raman Scattering

In this paper, silica nanoparticles (SiO2) were modified by using esterification and a large-area monolayer of SiO2 nanoparticles was fabricated by using the Langmuir-Blodgett (LB) assembly technique. Then, a layer of gold nanoshell was sprayed at this monolayer film to obtain a large-area SiO2/Au core-shell nanostructure for surface-enhanced Raman scattering (SERS). The synthesized SiO2 were characterized by transmission electron microscopy (TEM). The different surface pressures were studied to prepare an ordered close-packed silica monolayer. And the prepared SiO2 nanoparticle monolayer substrates were examined by scanning electron microscopy (SEM). Crystal violet (CV) and methylene blue (MB) were used as Raman scattering probe molecules to study the enhancement performance of the substrates. The characteristic vibrational bands of CV and MB were observed and assigned on the esterifiable silica nanoparticles substrates. The average Raman enhancement factors were discussed and the maximum was reached to 10(6). This experiment demonstrated that the large-area SERS substrates have an important application potential in the analytical measurement field.