Fabrication of Large-Area, High-Enhancement SERS Substrates with Tunable Interparticle Spacing and Application in Identifying Microorganisms at the Single Cell Level

The interparticle spacing of the surface-enhanced Raman scattering (SERS) substrate has a strong relationship with its enhancement factor (EF). How to precisely adjust the interparticle gap and generate SERS substrates with excellent quality and high reliability by a facile way is still a challenge. Here, we propose a convenient and environmentally friendly method to synthesize large-area Ag SERS substrates composed of either monodisperse nanoparticles (NPs), NP-linked nanowires (NWs), NW-weaved mesoporous membrane, or NP-aggregates by simply controlling the pH value in alkaline glucose solution, and their SERS enhancements have been evaluated. In addition, the EF of the Au NW-weaved film substrate prepared by our method is one order higher than that well-known dealloyed Au nanoporous substrate. Finally, the SERS spectrum of yeast at the single cell level is successfully acquired by using the highest EF substrate composed of monodisperse Ag NPs (∼8.24 × 10 7 ) in this work at a very low laser power (0.17 mW).