Silver nanosheet-coated inverse opal film as a highly active and uniform SERS substrate

The availability of well-controlled and reproducible substrates is critically important for surface-enhanced Raman spectroscopy (SERS)-based applications, but it remains a challenge at present. Herein, we report a facile strategy to prepare a new kind of SERS-active substrate, i.e., a two dimensional (2D) macroporous Ag film composed of a silver nanosheet (AgNS)-coated inverse opal film. The prepared substrate features good SERS reproducibility with a high enhancement factor (6 x 10(7)), enabling the ultra-sensitive detection of 10 fM rhodamine 6G (R6G). Moreover, the resultant substrate can be applied in the label-free detection of DNA with a sensitivity limit as low as 5 nM. Consequently, as a high-performance SERS-active substrate, the 2D AgNS-coated inverse opal film is promising for a myriad of chemical and biochemical sensing applications.