A SERS aptasensor for rapid detection of aflatoxin B1 in coix seed using satellite structured Fe3O4@Au nanocomposites

Coix seed is a minor cereal that has been used as a functional food in the Chinese diet due to its high nutritional value and health effects. These claimed health benefits include antioxidation, anti-cancer, anti-inflammation and enhancing immunological activity. But coix seed is easily contaminated by various mycotoxin, of which aflatoxin B 1 (AFB 1 ) is one of major threat to human and animal health. For the sake of detecting AFB 1 more effectively, a surface enhanced Raman spectroscopy (SERS) based aptasensor for rapid detection of AFB 1 in coix seed was developed. Fe 3 O 4 @Au nanoparticles (NPs) modified with aptamer which possess the ability of magnetic separation and excellent SERS activity were synthesized and characterized by transmission electron microscope. Ag NPs modified with 5,5′-dithiobis (2-nitrobenzoic acid) (DTNB) and complementary DNA (cDNA) were employed as SERS tags. Controllable hot spots were built by the combination of Fe 3 O 4 @Au NPs and Ag NPs through AFB 1 aptamer and cDNA, and also by the interparticle nanogapped between the different size of Au NPs. Based on the principle of competitive binding between AFB 1 and cDNA for aptamer, the rapid quantitative detection of AFB 1 in coix seed was realized. The limit of detection (LOD) was determined to be 0.0060 ng/mL, and a broad linear range between 0.01 and 100 ng/mL was achieved. The spiked recovery rates of coix seed sample were 98.2%–101.2%. The results demonstrated the promising potential of this aptasensor in rapid and effective detection of AFB 1 in foodstuffs. • A SERS aptasensor for the rapid detection of AFB 1 in coix seed was constructed. • Nanogapped Au NPs can provide a lot of controllable hot spots. • GMNPs modified with aptamer exhibited enrichment ability and excellent SERS activity.