A gold nanoflower based dual mode aptasensor for aflatoxin B1 detection using SERS and fluorescence effect simultaneously

Aflatoxin B1 (AFB1) is usually the major aflatoxin produced by toxigenic strains and has been identified the most potent natural carcinogen. Here, a SERS/fluorescence dual-mode nanosensor has been designed while gold nanoflowers (AuNFs) was used as substrate for the detection of AFB1. AuNFs exhibited excellent SERS enhancement effect as well as the good fluorescence quenching effect which made the dual signal detection possible. First, the surface of AuNFs was modified with AFB1 aptamer via Au-SH group. Then, the complementary sequence functionalized with Cy5 (the signal molecule) was attached to AuNFs based on the base complementary pairing principle. On this case, Cy5 was close to AuNFs, the SERS intensity was greatly enhanced and the fluorescence intensity was quenched. After incubation with AFB1, the aptamer was preferentially combined to its target AFB1. Thus, the complementary sequence detached from AuNFs which caused the SERS intensity of Cy5 decreased while its fluorescence effect recovered. Then, the quantitative detection was realized with two optical properties. The LOD was calculated to be 0.03 ng/mL. It was a convenient and fast detection method which expanded the application of nanomaterials based multi-signal simultaneous detection.