Self-enhanced electrochemiluminescence of luminol induced by palladium–graphene oxide for ultrasensitive detection of aflatoxin B1 in food samples

In this work, a novel and credible electrochemiluminescence immunoassay (ECLIA) was constructed for the ultrasensitive and highly selective detection of aflatoxin B1 (AFB1). Amino-functionalized 3D graphene hydrogel (NGH) served as the ECL platform with the self-enhanced ECL of luminol-palladium-graphene oxide (lum-Pd-GO) acting as a marker for the antibodies against AFB1. Pd-GO was synthesized by a self-redox method; it promotes the formation of reactive oxygen species, which are important to the ECL of luminol, from dissolved oxygen. The π-π conjunction between luminol and GO shortens their electron transfer distance, resulting in an amplified ECL signal (∼8.5 times larger than conventional luminol ECL). Moreover, 3D NGH, with its good conductivity, large surface area, and sufficient amino groups, was used to anchor gold nanoparticles (AuNPs), which subsequently immobilized bovine serum albumin (BSA)-AFB1 through Au-S bonds. The resultant, competitive ECLIA gave a relative low detection limit of 5 × 10-3 μg kg-1 and exhibited a broad linear relationship over the range of 0.05-50 μg kg-1. Finally, the proposed ECLIA was successfully used to analyze AFB1 contents in food samples. ECLIA: electrochemiluminescence immunoassay; AFs: Aflatoxins; HPLC: high-performance liquid chromatography.