A bifunctional AuNP probe-based enzyme-linked immunosorbent assay for facile and ultrasensitive detection of trace zearalenone in coix seed

•A facile and ultrasensitive nano-ELISA for zearalenone detection has been developed.•The sensitivity of nano-ELISA was closely related to the particle size of AuNPs and the two-step incubation strategy.•The developed nano-ELISA can be used to more accurately determine ZEN in real coix seed samples without any correction.•Nano-ELISA provides potential applications for other complicated matrices.