Cyclic peptide: a safe and effective alternative to synthetic aflatoxin B₁-competitive antigens

Aflatoxin B₁ (AFB₁) is one of the major mycotoxins, which naturally occurs in food and agricultural products. In this study, a cyclic peptide (CVPSKPGLC) mimicking AFB₁ was used to develop a biotinylated peptide-based immunoassay (bp-ELISA) for AFB₁ determination. This cyclic peptide was isolated from a commercially available phage-displayed random 7-mer cyclic peptide library, and then synthesized chemically. Instead of phage particles, the peptide was biotinylated and used to detect AFB₁ by bp-ELISA, with an IC₅₀ of 0.92 ng/mL, which was approximately 60-fold better than that of phage ELISA. Good recoveries (83-102%) were obtained in spiked rice and corn samples, which were further validated by high-performance liquid chromatography-fluorescence detector. As better sensitivities (0.92-1.21 ng/mL) were obtained by bp-ELISA even using selected anti-AFB₁ antibodies prepared previously in laboratory, this cyclic peptide is suitable as a substitute for synthetic competitive AFB₁ antigens in food contamination monitoring. Graphical abstract.