Self-Cross-Linked Collapsible Starch Aerogels Loaded with Ag Nanoparticles: A Platform for Multiphase SERS Detection of Trace Pollutants in Complex Matrices.

Regulating "hotspots" in surface-enhanced Raman scattering (SERS) constitutes a key research focus, whereas achieving highly sensitive and full-coverage detection of multiphase analytes remains a major obstacle to the widespread application of SERS technology. To address the drawbacks that most current SERS substrates are confined to single-phase detection and that multifunctional integrated substrates are in short supply, constructed three-dimensional Ag nanoparticle (AgNPs)-decorated cassava starch aerogels (ACA) as SERS substrates through a green and facile gelatinization, retrogradation, and freeze-drying approach. The method takes advantage of the gelling characteristic of cassava starch (CS) and the in situ reduction capacity of cassava dialdehyde starch (CDS). The substrate possesses both superhydrophilic features and a collapse-induced mechanism: upon contact with aqueous solutions, its three-dimensional porous scaffold undergoes directional collapse, reducing the distance between AgNPs to generate high-density SERS "hotspots" and remarkably boosting detection sensitivity. Its three-dimensional interconnected pore structure and large specific surface area enable effective entrapment of gaseous, liquid, and solid analytes, overcoming the constraints of conventional substrates and achieving swift, sensitive, and quantitative detection of multiphase targets using a single substrate. With rhodamine 6G (R6G) and crystal violet (CV) as probe molecules, the enhancement factors (EF) were determined to be 6.8 × 108 and 5.6 × 108, respectively. In practical application, the adsorption method was adopted to detect gaseous 4-aminothiophenol (4-ATP), with a limit of detection (LOD) of 0.64 mg/L. Meanwhile, liquid and solid thiabendazole (TBZ) residues in food samples were measured via extraction and swabbing approaches, whose corresponding limits of detection were 0.063 mg/L and 0.067 mg/L separately. The findings demonstrate that the ACA SERS substrate exhibits high sensitivity and can quickly detect multiphase analytes, and the analytical platform holds great potential in the fields of food safety inspection and ecological monitoring.