Dual-competitive lateral flow aptasensor for detection of aflatoxin B1 in food and feedstuffs.

A novel dual-competitive lateral flow aptasensor (LFA) benefited from aptamer and lateral flow strips was first designed by using aflatoxin B1 (AFB1) as the model target. In this LFA assay, the target AFB1 competed with AFB1-hapten at T line for binding to Cy5-labeled AFB1 aptamer and the complementary strand competed with the target AFB1 for binding to Cy5-labeled AFB1 aptamer at C line. The ratio of their fluorescent intensities at the T line and C line (ST/SC ratio) was employed in order to increase the sensitivity for target AFB1 detection. This technique has the limit of detection (LOD) of 0.1ng/mL for AFB1 within the linear range from 0.1ng/mL to 1000ng/mL. Subsequently, the LFA approach was validated using 11 kinds of food and feedstuff samples with a simple aqueous extraction protocol. The test results with different naturally contaminated feedstuffs indicated a good correlation between this LFA and a commercial ELISA kit. The assay can be completed within 20min and its sensitivity, specificity and reproducibility are highly satisfactory. This is the first LFA that has been rigorously validated, which will be greatly beneficial to development of commercial aptamer-based biosensors for food safety, environmental analysis, particularly in clinical diagnosis.