Synchronous enhancement of electromagnetic and chemical effects-induced quantitative adsorptive detection of quercetin based on flexible polymer-silver-ZIF-67 SERS substrate

Surface-enhanced Raman scattering (SERS) is a prospective and ultrasensitive analytical technique because of its prominent molecular fingerprint diagnosis ability. Nonetheless, the tested molecules are typically required to be steadily attached onto a SERS-active region, which makes it tough to monitor feebly adsorbed molecules. In this study, a polydimethylsiloxane (PDMS)-based flexible SERS substrate combined with silver nanocubes (Ag NCs) and ZIF-67 was developed with a facile layer-by-layer strategy. A superhigh enhancement factor (EF) of 9.1 × 108 M was obtained by electromagnetic enhancement from the promising Ag NCs in conjunction with the molecular anchoring surface and chemical enhancement ability of ZIF-67. Furthermore, the practical SERS-based detection of quercetin with an ultra-low limit of detection (LOD) of 2.3 × 10−5 mg/mL was subsequently achieved utilizing this multifunctional substrate, indicating its intriguing outlook in the direct monitoring of food nutrients. Notably, the intrinsic Raman signal at 2905 cm−1 of PDMS framework was adequately utilized as an internal standard to promote the reliability of such detection. It is anticipated that this smart platform with both prominent SERS performance and quantitative test ability may find an extensive application in the domains of food and biochemical assay.