Detection of Cotinine (Spiked in Human Urine) Using Plasmonic Quasi Crystal as SERS-active Substrate

During light-matter interaction, light gets absorbed, reflected, transmitted, and scattered. Depending on the scattering behaviour of light, in 1928, Sir C.V. Raman discovered that one in a million photons can get inelastically scattered when light interacts with matter. Raman signals provide the unique spectral fingerprint of a Raman active analyte; however, owing to their low scattering cross-sections, Raman signals are weak in nature [1]. A variant of Raman spectroscopy, that is Surface enhanced Raman spectroscopy (SERS) can detect single molecules and provide comprehensive chemical information about molecular assemblies by enhancing Raman signals substantially by increasing the Raman scattering cross-section. It is a label-free, non-destructive detection method that is rapid, sensitive, accurate, and precise. The major applications of SERS are: (a) environmental monitoring; (b) narco-analysis; (c) gas sensing; (d) food adulteration; and (e) bio-diagnostics, among others [2]–[3].