Applied Nanophotonics, Liquid Crystals and Biomedical Optics

Surface-enhanced Raman scattering (SERS) from silver nanosculptured thin films (STF) was studied in detail for biosensing. The influences of the nanostructures' sizes, topology, the substrate features, and the preparation conditions on the enhancement were examined. Enhancement factors on the order of 10⁷ were obtained from silver nanorods deposited on bare silicon substrates with respect to their dense counterparts, using 4-aminotheophenol (4-ATP) for the Raman emission. The low detection limit that can be achieved with STFs is below 1 μg/lit of the probe molecule 4-ATP in Ethanol solution. Theoretical modeling based on a single small spheroidal nanoparticle helped in explaining the main properties of SERS from STFs. Stability of the films was noticed over a period of one year without significant degradation.