Fluorescence resonance energy transfer-based aptasensor for rapid detection of aflatoxin M1 in milk

A novel aptasensor for the detection of aflatoxin M1 (AFM1) was developed based on the fluorescence resonance energy transfer (FRET) effect between gold nanoparticles (AuNPs) and FAM-labeled cDNA (FAM-cDNA). Additionally, magnetic nanoparticles (Fe₃O₄ NPs) were attached with AuNPs to construct a Fe₃O₄@AuNPs system that was easy to separate by the external magnetic field. In this aptasensor, FAM-labeled cDNA and Fe₃O₄@AuNPs acted as donor and acceptor, respectively. In the presence of target AFM1, the aptamer of this aptasensor specifically recognized with AFM1, resulting in a turn-on fluorescence signal due to target-induced dissociation of FAM-cDNA from the FRET pair. The morphology, size and functional group of Fe₃O₄@AuNPs were characterized by TEM, XRD and FT-IR. The UV-vis absorption spectroscopy and fluorescence spectroscopy were used to determine the construction of Fe₃O₄@AuNPs@Apt@FAM-cDNA aptasensor. Under optimal conditions, the linear concentration range of 1-100 ng/mL, limit of detection (LOD) of 0.20 ng/mL, and recoveries of 99%~101% of the aptasensor were obtained. Overall, this aptasensor with satisfied sensitivity and selectivity are promising to be applied in the detection of other biochemical analytes in the future.