HS-β-cyclodextrin-functionalized Ag@Fe3O4@Ag nanoparticles as a surface-enhanced Raman spectroscopy substrate for the sensitive detection of butyl benzyl phthalate.

In recent years, there have been incidents involving the illegal addition of phthalic acid esters (PAEs) to liquors. It is well known that PAEs such as butyl benzyl phthalate (BBP) have estrogen-like effects, so high PAE levels in the body can lead to a decreased sperm count in males and altered sexual organ development in children, for example. The rapid detection of PAEs in liquor is therefore an important task. Compared with traditional methods of testing for PAEs, surface-enhanced Raman spectroscopy (SERS) offers higher sensitivity and the ability to search for chemical fingerprints, allowing the rapid detection of particular PAEs. In the present work, we synthesized Ag@Fe3O4@Ag/β-cyclodextrin (CD) nanoparticles for use as a SERS-active substrate. Fe3O4 aggregates quickly under the influence of an external magnetic field, making it possible to magnetically separate out the NPs, which simplifies sample processing. The detection limit of the system for PAEs is also improved because the β-CD acts as a functional group with a cavity structure that is capable of adsorbing BBP to form a host (β-CD)-guest (BBP) complex. This substrate was shown to possess good repeatability and sensitivity when using malachite green (MG) as a probe molecule. Furthermore, the nanoparticle-based SERS substrate permitted the detection of BBP down to a level of 1.3 mg/kg in liquor, which is low enough to be able to detect BBP in real-world liquor samples. We expect that this method will prove useful for the rapid detection of PAEs in food. Graphical abstract.