Dual SERS-enhanced core-shell-satellite assemblies with Cu-doped ZIF-8 interlayer for OTA detection

Ochratoxin A (OTA) is a highly toxic and bioaccumulative mycotoxin found in grains, threatening food safety. Surface-enhanced Raman spectroscopy (SERS) combined with immunochromatography enables rapid and sensitive detection of OTA. This study aimed to develop a novel core-shell-satellite SERS probe (Au@Ag@(Cu-ZIF-8)-AuNPs) for OTA detection. The structure comprised an Au@Ag nanoparticle core, coated with Cu-doped ZIF-8 and gold nanosatellites. This design generated dense electromagnetic “hot spots” through plasmonic coupling between the core and satellites. Simultaneously, Cu doping reduced the bandgap of ZIF-8, thus enhancing charge transfer efficiency for chemical signal amplification. The dual electromagnetic-chemical enhancement achieved a detection range of 0.1 fg/mL–1.0 μg/mL and an ultralow detection limit of 0.057 fg/mL, thereby surpassing the detection limits of conventional methods. This innovative probe, with its high sensitivity and wide dynamic range, offers a powerful platform for mycotoxin monitoring, hence advancing SERS-based rapid detection technologies crucial for food safety.