Fabrication of Gyroid‐Structured Metal/Semiconductor Nanoscaffolds with Ultrasensitive SERS Detection via Block Copolymer Templating.

Surface‐enhanced Raman scattering (SERS) is a label‐free and powerful technique for monitoring dynamic molecular processes with high sensitivity and reproducibility. SERS has diverse applications in medicine, molecular science, biology, and chemical sensing. In this study, a template‐based approach to create an ultrasensitive SERS‐active substrate is proposed which involves combining nanostructured semiconductors and noble metals. A nanoporous polymer obtained from hydrolyzed gyroid‐forming polystyrene‐block‐poly(l‐lactide) (i.e., PS‐b‐PLLA) is used as a template for Ag reduction and TiO2 sol–gel reaction. After calcination to remove the polymeric template, TiO2 nanoscaffolds appear as self‐supporting 3D nanoobjects with homogeneously and closely distributed Ag nanoparticles, providing a high density of regions with intense local field enhancement (hotspots). Rhodamine 6G molecules are used as probe molecules to demonstrate the SERS performance, revealing a markedly high average enhancement factor of up to 1014. The intrinsic photocatalytic properties of TiO2 can degrade target organic chemicals for the self‐cleaning and reproduction of SERS‐active substrates. Moreover, a simple hydrazine reduction‐based approach is applied for the formation of regenerated Ag/TiO2 nanoscaffolds to reduce the use of Ag‐based SERS‐active substrates, decreasing the costs associated with relevant industrial processes. [ABSTRACT FROM AUTHOR]