Timeshare surface-enhanced Raman scattering platform with sensitive and quantitative mode

The sensitivity and quantification capability of surface-enhanced Raman scattering (SERS) substrates are mutually exclusive, because the ultrasensitive SERS sites (hottest spots) necessary for the sensitivity will significantly magnify the SERS signals of the analyte molecules and thus each of these molecules will be miscounted to be hundreds during the quantification process. We demonstrate a concept to circumvent the above contradiction by engineering a timeshare SERS platform capable of working at the quantitative or the sensitive mode on demand. The timeshare SERS platform was constructed by transferring a monolayer gold nanosphere film onto elastic substrates (e.g., hydrogel). The volume change of the hydrogel could adjust the inter-nanosphere distance, dynamically controlling the formation or extinction of the SERS hottest spots on the same SERS substrate without influencing the spatial distribution of the analyte molecules. The timeshare SERS platform without the SERS hottest spots showed strong quantification capability, while when equipped with a substantial number of the SERS hottest spots exhibited ultrahigh sensitivity. We demonstrated quantitative and ultrasensitive detection of various analyte molecules using the quantitative and the sensitive mode of the timeshare SERS platform, respectively. We opened an avenue towards designing SERS substrates with both high sensitivity and strong quantification capability.