Effect of aggregation of Ag nanoparticles suspended in aqueous solution on surface enhanced Raman scattering

Technology of surface enhanced Raman scattering (SERS) on substrate based on film of noble metal nanoparticles has many advantages of application and potentiality in molecular biology, immunoassay of medicine and organic molecules, etc. In this work, in order to research SERS, sodium citrate was employed as aggregation reagent to induce the aggregation of Ag nanoparticles modified by 4-mercaptobenzoic acid. And the "hot spots" resulted from the aggregation were used to enhance the SERS spectra. Strong SERS spectra of 4-mercaptobenzoic acid molecules were observed. In conclusion, "hot spots" of aggregation of Ag nanoparticles modified by 4-mercaptobenzoic acid in aqueous solution has highly effect of SERS.