Interface engineering with self-assembling Au@Ag@β-cyclodextrin bimetal nanoparticles to fabricate a ring-like arrayed SERS substrate for sensitive recognition of phthalate esters based on a host–guest interaction and the coffee ring effect

Herein, Au@Ag@β-cyclodextrin (β-CD) nanoparticles with a relatively uniform shape and size of ∼13 nm in diameter have been successfully synthesized, and the surfaces of the synthesized nanoparticles are successful modified by β-CD. A highly efficient synthetic approach was developed for the preparation of a surface-enhanced Raman spectroscopy (SERS) substrate, which self-assembles Au@Ag@β-CD nanoparticles and analytes into a coffee ring pattern via the coffee ring effect. The coffee ring effect can make phthalates (PAEs) aggregate to the edge together with the Au@Ag@β-CD nanoparticles and concentration enrichment can be achieved. In addition, the surface of the core-shell Au@Ag@β-CD is modified with β-CD with a cavity structure, which can enrich analyte concentration by adsorbing the analytes into the hydrophobic cavity using host-guest recognition. This enrichment process not only improves the concentration of the surface of the analyte but also effectively distinguishes it from other substances in the analyte solution. The mechanism of enrichment and host-guest recognition is verified by subsequent molecular docking simulation. Thus, a ring-like arrayed SERS substrate with dual-strategy enrichment is used to detect PAEs. The experiments using the ring-like arrayed SERS substrate, gave a limit of detection of 0.2 nM for DOP detection, the recovery rate of the spiked samples ranged from 92.3% to 106.6%, and an RSD of less than 6% for PAE detection is obtained. This work provided a simple, rapid, low-cost, highly sensitive and stable method for PAE detection in life and the environment.