Development of a colorimetric/fluorescence dual-mode immunoassay for aflatoxin B1 based on streptavidin-induced gold nanoparticle aggregation

A dual-mode immunoassay method was developed for colorimetric and fluorescence detection of aflatoxin B1 (AFB1) based on streptavidin-induced gold nanoparticle aggregation (AuNP@SA). AuNP-modified streptavidin–biotin labeling AFB1 complete antigen aggregations (AuNP@SA@Bio-BSA-AFB1) were synthesized as the competitive binding and dual-mode probe. AuNP@SA@Bio-BSA-AFB1 aggregations possessed high colorimetric and fluorescence quenching intensities. AFB1 antibodies modified immunomagnetic microspheres were used as the capture probe. The competitive binding between AFB1 and AuNP@SA@Bio-BSA-AFB1 leads to changes in color and fluorescence intensity. The detection limit of the colorimetric method is 6.95 ng·mL⁻¹, while that of the fluorescence method is 0.07 ng·mL⁻¹. The practicality of the proposed strategy was demonstrated by determining AFB1 in spiked peanut samples.

Graphical Abstract