Sniffing a single molecule through SERS using Aucore-Agshell bimetallic nanoparticles

In this communication we have described the preparation of a new class of core-shell type, i.e. Au c o r e -Ag s h e l l bimetallic nanoparticles by seed-mediated technique to examine the surface-enhanced Raman scattering (SERS) involving these particles. It has been demonstrated how the thickness of the Ag-shell could be tuned with the variation of gold seed to Ag-ion ratio with a view to examine the impact of the size and field effects of these bimetallics on SERS spectra. The sensitivity of the SERS detection limit has been improved down to the single molecular level through the formation of hot-particles due to aggregation of core-shell type particles in the presence of NaCl.