Development of an electrochemical aptasensor based on Au nanoparticles decorated on metal–organic framework nanosheets and p-biphenol electroactive label for the measurement of aflatoxin B1 in a rice flour sample

This study purposes designing a new aptasensor to detect aflatoxin B1 (AFB1). The AFB1 aptasensor was developed by growing gold nanoparticles on the surface of nickel-based metal–organic framework nanosheets (AuNPs/Ni-MOF) and an electroactive indicator ( p -biphenol, PBP). The AFB1 aptamer was immobilized on the AuNPs/Ni-MOF and then hybridized with the complementary DNA (cDNA). PBP was intercalated within the double helix of the cDNA–aptamer. The difference between electrochemical responses of intercalated PBP before and after incubation of AFB1 with the immobilized aptamer was considered as an analytical response. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to monitor the construction processes of the aptasensor. By recording the differential pulse voltammograms of PBP in phosphate buffer (pH 7.0, 0.1 M), the linear range and the detection limit of AFB1 were found to be 5.0 × 10 −3 –150.0 ng mL −1 and 1.0 × 10 −3 ng mL −1 ( S / N = 3), respectively. Finally, the designed aptasensor has been successfully used to measure AFB1 in a rice flour sample with satisfying results. Graphical abstract Schematic illustrated the different steps of constructing the electrochemical aptasensor based on Au nanoparticles decorated on Ni-metal–organic framework nanosheets and p-biphenol electroactive label for measuring aflatoxin B1 (AFB1).