Dual-layers Raman reporter-tagged Au@Ag combined with core-satellite assemblies for SERS detection of Zearalenone

[Display omitted] •A SERS-based competitive immunosensor was developed for ZEN detection.•Core-shell structure AuMBA@AgMBANPs were proposed as the SERS tags.•Branched gold nanostars generate strong electromagnetic field.•Lower limit of detection was sensitive for practical application.•High specificity and satisfactory recoveries for real sample detection. Zearalenone (ZEN) is a prevalent mycotoxin identified in corn. A SERS-based immunosensor by constructing core-satellite assemblies was developed for ZEN detection. ZEN monoclonal antibody modified gold nanostars (AuNSs) were fabricated as the capture probe (core). The Raman signal probes (satellites) utilized ZEN antigen linked to the core–shell structures loaded with two layers of Raman reporter molecules (AuMBA@AgMBANPs). The coupling between AuNSs and AuMBA@AgMBANPs can produce a poweful electromagnetic field, thus considerably amplifying the Raman signal. The detection range of ZEN for corn samples under the optimal conditions was 5 ∼ 400 μg/kg with a LOD of 3 μg/kg, which completely satisfying the requirement of maximum residual level (60 μg/kg). Moreover, the proposed SERS method was consistent with the HPLC-FLD method for the detection of ZEN in naturally contaminated corn samples (90.58% ∼ 105.29%). Conclusively, fabricated immunosensor with exceptional sensitivity and specificity broaden the application of SERS in mycotoxin detection.