Label-free ratiometric homogeneous electrochemical aptasensor based on hybridization chain reaction for facile and rapid detection of aflatoxin B1 in cereal crops.

Aflatoxin B1 (AFB1) contamination has raised global concerns in agricultural and food industry; thus, sensitive, accurate and rapid AFB1 sensors are essential in many circumstances. Herein, we developed a label-free and immobilization-free ratiometric homogeneous electrochemical aptasensor based on hybridization chain reaction (HCR) for facile and rapid determination of AFB1. Methylene blue (MB) and ferrocene (Fc) were used as label-free probes to produce a response signal (IMB) and a reference signal (IFc) in solution phase, respectively. The ratio of IMB/IFc was used as a yardstick to quantify AFB1. HCR was exploited to enlarge the intensity of IMB as well as ratiometric signal. By combining label-free homogeneous assay and ratiometric strategy, the resulting aptasensor offered sensitive, rapid, and reliable determinations of AFB1 with a detection limit of 38.8 pg mL-1. The aptasensor was then used to determine AFB1 in cereal samples with comparable reliability as HPLC-MS.