Abstract
This review discusses the surface-enhanced Raman scattering (SERS) with efficiencies enhanced by as much as 1014-1015 fold as well as a SERS cross section on the order of 10-17-10-16 cm2/molecule. Despite the existing controversy on the origin of the enhancement, SERS effect offers new opportunities for spectroscopic detection of single molecules near or on the surface of metallic nanoparticles. There has been a considerable amount of research on explanation of the enhancement mechanism and on developing SERS labels as bio-analytics tools for either molecular multiplexed detection or bio-imaging at different levels.