Developing a simple and reliable method for the detection of the highly concerning mycotoxin, aflatoxin B1 (AFB1), is of great importance to food safety monitoring. In this study, a simple electrochemical aptasensor was presented for the detection of AFB1 based on the host-guest recognition between ferrocene and β-cyclodextrin (β-CD). Fc-labeled aptamer of AFB1 first hybridized with its complementary Fc-cDNA. Two ferrocene molecules were brought closely together and couldn't enter into the cavity of β-CD modified on the electrode. Negligible signal could be observed. Once AFB1 captured the aptamer from the AFB1-sensitive dsDNA, Fc-cDNA was released and subsequently entered into the cavity of β-CD to form inclusion complexes, giving rise to an distinct increase of Ret and peak current because of the molecular recognition of β-CD. AC impedance method is more sensitive than DPV method. The electrochemical aptasensor displayed a sensitive response to AFB1 in a wide linear range of 0.1 pg/mL to 10 ng/mL, with a low detection limit of 0.049 pg/mL (0.147 pmol/mL) by AC impedance detection, which is 10-100 lower than previously reported methods. The aptasensor has good selectivity and reliability, which has been successfully applied to the determination of AFB1 in real peanut oil samples with recoveries ranging from 94.5% to 106.7% and inter-assay RSD lower than 11.51%.
Keywords: AC impedance; Aflatoxin B1; Differential pulse voltammetry; Electrochemical aptasensor; Host-guest recognition; β-cyclodextrin.
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