Over the last decade

Over the last decade, noble-metal nanoparticles have attracted considerable attention due to their unique optical response in interaction with light. When the frequency of the electromagnetic radiation resonates with the collective oscillation of the conduction electrons in noble-metal nanoparticles, localized surface plasmon resonance (LSPR) occurs. This phenomenon can be observed as an intense UV-Vis-NIR absorption band, whose precise spectral position depends on the particles size, shape, surrounding environment and degree of assembling. LSPR is the basis of many applications such as photothermal therapy, biological and chemical sensing and, also, bioimaging via surface-enhanced spectroscopies.
Surface enhanced Raman spectroscopy (SERS) consists in using large local field enhancements that occur near the surface of nanoparticles due to plasmon excitation to intensify the Raman scattering signal of molecules at or near the surface. Although, it is well known that SERS enhancement is explained by two mechanism: the electromagnetic enhancement and the chemical enhancement, the second one is playing a less important role. In the beginning, SERS was considered to be a tool for physical scientists. However, recent papers demonstrated that SERS can be implemented in medical applications by using SERS nanotags for living cells imaging.