Strategy on Increasing Surface-Enhanced Raman Scattering from Gold Nanoparticles

H.-C. Chen, K.-H. Yang, Y.-C. Liu, C.-C. Yu
Taipei Medical University, TW

Keywords: surface-enhanced Raman scattering, gold nanoparticle, electrochemical method

Summary:

In this work, we employ a simple pathway to prepare SERS-active substrates with Au nanoparticles (NPs) by sonoelectrochemical deposition-dissolution cycles. Moreover, in general SERS studies, SERS-active metal substrates are first prepared. Then probe molecules are adsorbed on them to evaluate the relative SERS effects. In this study, model probe molecules of 2 × 10-6 M Rhodamine 6G (R6G) was added in electrolytes for preparing SERS-active substrate with R6G-adsorbed Au NPs for one step. Encouragingly, based on this strategy, the SERS intensity of adsorbed R6G can be increased by more than one order of magnitude, as compared with that of R6G adsorbed on a SERS-active Au substrate by using a conventional procedure, which was generally shown in the literature. Moreover, this improved SERS effect based on this strategy is also effective for 1 × 10-4 M probe molecules of 4-mercaptopyridine (4-MP). Meanwhile, the limit of detection (LOD) for R6G measured by using this strategy is markedly reduced to 2 × 10-14 M. Further analyses indicate that the increase in SERS activity in this new method is most likely due to the incorporation of more chloride ions into the substrate, which may increase the effective hot spots of SERS.