Aptamers Adsorbed on WSe2 Nanosheets in a Label-Free Colorimetric Aptasensor for Ochratoxin A

Ochratoxin A (OTA) poses a great threat to human health, and its rapid detection has drawn wide concerns in agri-food product risk assessment. Herein, on the basis of the aptamer-enhanced peroxidase-mimetic property of two-dimensional few-layer tungsten diselenide (WSe2) nanosheets, a simple label-free colorimetric aptasensor is presented for OTA detection. The enzymatic mimic property of the WSe2 nanosheets could be enhanced through aptamer adsorption because of the enhanced affinity of WSe2 nanosheets to 3,3′,5,5′-tetramethylbenzidine. A good linear relationship was obtained in the range from 0.5 to 50 ng/mL, and the limit of detection for OTA was 0.16 ng/mL. The performance of this strategy was comparable to previous strategies for OTA determination. Further, this colorimetric aptasensor displayed satisfying specificity and stability in a complex food matrix including both red wine and wheat flour samples. Hence, the results of this study suggest potential applications of the aptasensor to detect mycotoxins in different agri-food products.