An Aptamer-based Dipstick Assay for the Rapid and Simple Detection of Aflatoxin B1

A rapid and simple dipstick assay based on an aptamer has been developed for the determination of aflatoxin B1 (AFB1). The dipstick assay format was based on a competitive reaction of the biotin-modified aptamer specific to AFB1 between target and cy5-modified DNA probes. Streptavidin and anti-cy5 antibody as capture reagents were immobilized at test and control lines on a membrane of the dipstick assay. After optimization, the limit of detection for the dipstick assay was 0.1 ng/ml AFB1 in buffer. The method was confirmed to be specific to AFB1, and the entire process of the assay can be completed within 30 min. Aqueous methanol (20%) provided a good extraction efficiency, and the matrix influence from corn extracts was successfully reduced through 2-fold dilution. The results of AFB1 analysis for corn samples spiked with known concentration of AFB1 by the dipstick assay and ELISA showed good agreement. The cut-off value of the dipstick assay for corn samples was 0.3 ng/g AFB1. Therefore, the dipstick assay is first reported and considered as a rapid, simple, on-site and inexpensive screening tool for AFB1 determination in grains as well as a corn.