A Highly Sensitive and Rapid-Response M-Hydrogel SERS Chip for Enrichment Detection of Environmental Pollutants

Surface-enhanced Raman scattering (SERS) substrates with high sensitivity, reproducibility, and stability are essential for trace analyte detection, yet conventional rigid substrates often suffer from limited molecular enrichment capacity and inconsistent hot spot generation. In this study, we developed a new flexible modified hydrogel (M-hydrogel) chip with a simple and scalable manufacturing process. Capitalizing on its high expansibility, the chip generates negative pressure that promotes the rapid intake of target molecules. Subsequent contraction enriches analytes within a confined space while simultaneously inducing AgNP aggregation to form dense and uniform SERS hot spots, significantly enhancing detection sensitivity. The substrate demonstrated an exceptional detection limit of 10–7 M for crystal violet (CV) and an enhancement factor of 8.43 × 106. It also exhibited remarkable signal reproducibility and long-term stability. Furthermore, the SERS detection of CV displayed a wide dynamic concentration range with a strong linear relationship between the characteristic peak intensity and the logarithm of analyte concentration. The entire pretreatment and detection procedure requires less than 35 min, underscoring the platform’s great potential for rapid, quantitative monitoring of environmental pollutant residues.