On-line adapted islands SERS Chip for quantitatively sensing H₂S molecules in food spoilage

Surface-enhanced Raman scattering (SERS) has extraordinary potential in detecting hydrogen sulfide (H₂S) gas molecules due to its high sensitivity and specificity. However, constructing SERS substrates with strong Raman signal enhancement effects has been a major challenge. In this study, a gold/silver nanostars (Au/Ag NSs) islands chip was developed, leveraging the phenomenon that the SERS enhancement can be significantly improved by patterning plasmonic metals with micro/nanostructures. Compared to the SERS mapping spectrogram of the conventional homogeneous Au/Ag NSs chip, uniform and dense hot spots were formed on the surface of the island chip, which is the key to remarkable enhancement of Raman signal. Both chips were functionalized with 4-mercaptophenylboronic acid (4-MPBA) for the quantitative detection of H₂S. The islands chip displays 1.6 folds and 2 orders higher blank Raman signal intensity and a limit of detection (LOD) for H₂S than conventional homogeneous SERS chips, respectively. The islands chip is also used for on-line monitoring of spoilage in high-protein foods. The detection ranges for H₂S were 2 × 10^-8 M - 2 × 10^-3 M, with a LOD of 1.9 nM. This sensing strategy provides not only a novel approach for on-ling gaseous hazards detection for food spoilage but also a potential possibility for monitoring gas molecules in the environment.