Layered Assembly of Silver Nanocubes/Polyelectrolyte/Gold Film as an Efficient Substrate for Surface-Enhanced Raman Scattering

Surface-enhanced Raman scattering (SERS) is of great importance for the sensitive, rapid, and repeatable detection of target analytes. The electromagnetic enhancement has a major contribution to the signal enhancement in SERS which is critically dependent on the micro-/nanomorphology of noble metal (e.g., Au and Ag) film substrates. Herein, Ag nanocubes/polyelectrolyte/Au (Ag/PE/Au) sandwich-structured film is fabricated by the layer-by-layer deposition and then utilized as an efficient SERS substrate by the coupling of localized surface plasmons (LSPs) and surface plasmon polaritons (SPPs) resonances while the electromagnetic field enhancement is confined within the PE gap layer which is sandwiched between Ag nanocubes and Au film. With rhodamine 6G and crystal violet as the probe molecules, the Ag/PE/Au sandwich-structured film demonstrates highly sensitive SERS signals, which is further supported by the theoretical simulations as well. This work indicates that the Ag/PE/Au sandwich-structured film can be employed as a reliable SERS substrate for sensitive molecular sensing applications.