Abstract: In this study, a fluorescent “turn-on” biosensor for rapid and sensitive detection of deoxynivalenol (DON) in grains was developed based on randomly arrayed G-rich DNA sequence and endonuclease digestion. This template-independent G-quadruplex (G4) could form a stable fluorescent complex with G4-specific dye, enhancing the fluorescence intensity. Under the optimal conditions, DON was sensitively detected in a wide linear range from 0.1 to 60 ng/mL with a limit of detection (LOD) of 10 pg/mL. The proposed method showed good selectivity, repeatability and stability. It was successfully applied to the determination of DON in wheat and corn samples, and recoveries from 94% to 112% were obtained with relative standard deviation (RSD) of 3.4%–4.9%. This strategy possessed many advantages, including simplicity, rapidity, no need for label, low cost and high sensitivity, and therefore could be useful for the detection of DON in grains.

Key words: mycotoxins; deoxynivalenol; biosensing; G-quadruplex; rapid detection