Development of an aptasensor for the fast detection of Versicolorin A

• Versicolorin A is a precursor of aflatoxin B1 (AFB1) but much lower toxic than AFB1.
• The aptamer of Versicolorin A was selected by Isothermal Titration Calorimetry.
• An electrochemical aptasensor was developed for fast-detection of Versicolorin A.
• The aptamer is potentially developed to be an affinitive column for solid phase extraction.

Aflatoxins (AFs) are secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. The molds may contribute to pre-harvest aflatoxin contamination of susceptible crops. For the customer and food producer, a predictive model for aflatoxin detection is very desirable. Versicolorin A (VerA), which is the first precursor in the pathway of aflatoxin B1 (AFB1) biosynthesis, shares similar toxic group with the furofuran structure in aflatoxin B1. VerA exhibits a much lower teratogenic toxicity than AFB1 and may be used as a predictive indicator for aflatoxin B1 contamination of storage crops. Therefore, the development of a fast detection method for VerA is important. One of the randomly computer-generated aptamers of VerA was confirmed by isothermal titration calorimetry with Kd = 9.26 × 10−6 mol l−1. In addition, a simple and sensitive label-free aptasensor was developed for the electrochemical detection of VerA. According to the results from differential pulse voltammetry (DPV), a linear relationship existed between the log conc. of VerA (ranged from 0.01 to 100 ng ml−1) and the current (△Ip) with a limit of detection (LOD) of 10 pg ml−1. The resulting aptasensor exhibited good reproducibility for detecting VerA and stability after storage for 15 days at 4 °C with acceptable anti-interference against ZEN, OTA, DON, and FB1. When used in corn samples, the recoveries of VerA were determined to be in the range of 81.3%–104.4 %. Although with some intercross, result suggests that the obtained aptamer for VerA is potentially used as a sorbent for the preparation of solid-phase-extraction procedure to clean up food samples in conjunction with high-performance liquid chromatography analysis.