Fabrication of tunable Au SERS nanostructures by a versatile technique and application in detecting sodium cyclamate

In this work, three typical morphologies of SERS substrates with the compositions of Au nanoparticles, short Au nanowires (NWs) with small Au nanoparticles filled in the nanogaps and long Au NWs intertwined into a self-supporting film, were fabricated by a versatile nanocluster fabrication technique. This physical fabrication technique is easy to implement and cost-effective, and the fabricated SERS substrates have a large-area, good homogeneity and long-term stability. More importantly, the SERS substrates prepared by this physical method will not incorporate reductants and surfactant chemicals, and thus can yield clean surfaces, which are suitable for analytes with a weak affinity to the substrate surface. In this study, the fabricated substrate with the highest enhancement factor (EF) successfully acquired the SERS spectrum of sodium cyclamate, a restricted food additive, with a good signal–noise-ratio. Finally, a set of piece-wise linear equations were produced according to the correlation between SERS intensity and sodium cyclamate concentration with a detection limit of 1.6 × 10−9 M.