Timeshare Surface-Enhanced Raman Scattering Platform with Sensitive and Quantitative Mode
Surface-enhanced Raman scattering (SERS) substrates face an intrinsic trade-off: the ultrasensitive hottest spots required for single-molecule detection amplify analyte signals by orders of magnitude, causing each molecule to be miscounted as hundreds during quantification. This study demonstrates a timeshare SERS platform that circumvents this contradiction by dynamically toggling between quantitative and sensitive modes on demand. The platform is constructed by transferring a monolayer gold nanosphere film onto an elastic hydrogel substrate. The hydrogel's volume change adjusts the inter-nanosphere distance, reversibly controlling the formation or extinction of SERS hottest spots without altering the spatial distribution of analyte molecules. In the absence of hottest spots, the platform exhibits strong quantification capability; when equipped with a substantial number of hottest spots, it achieves ultrahigh sensitivity. The authors demonstrate quantitative and ultrasensitive detection of various analyte molecules using the respective modes. This approach opens a route to designing SERS substrates that simultaneously offer high sensitivity and robust quantification, addressing a long-standing bottleneck in trace detection for analytical chemistry, environmental monitoring, food safety, and biomedical diagnostics.