The formation of hot spots is an effective approach to improve the performance of surface-enhanced Raman scattering (SERS). Silk nanoribbons (SNRs), with a height of about 1-2 nm, and Au nanoparticles (AuNPs) were assembled by electrostatic interactions to introduce sandwich hot spot structures. These sandwich structures were optimized by tuning the ratio of SNRs and AuNPs, resulting in strong SERS signals with a sensitivity of 10-13 M and enhancement factor (EF) of 5.8 × 106. Improved SERS spectrum uniformity with relative standard deviation (RSD) about 11.2% was also achieved due to the homogeneous distribution of these hot spot structures. The inherent biocompatibility of SNRs and facile fabrication processes utilized endowed the SERS substrates significant benefits toward biomedical applications, confirmed by cytocompatibility and improved SERS bioimaging capacity in vitro. The results of this study suggest the feasibility of forming high performance bioimaging systems through the use of naturally derived materials with special nanostructures.
Keywords: SERS; gold; hot spots; nanoribbons; sandwich structure.