A fluorescence and colorimetric dual-mode sensor based on the aptamer-adsorbed hollow cerium oxide for sensitive and visual detection of Aflatoxin B1 in food

A sensor capable of dual-mode operation was developed to detect Aflatoxin B 1 (AFB 1 ) through the concurrent alterations in fluorescence and colorimetric signals. The AFB 1 aptamer modified with Cy5 (Cy5-Apt) was adsorbed on the surface of hollow cerium oxide (HCeO 2 ) to form Cy5-Apt@HCeO 2 sensor. The fluorescence of Cy5 was extinguished, whereas the peroxidase-like activity of HCeO 2 was amplified, enabling it to catalyze the reaction between TMB and H 2 O 2 , resulting in a profound blue coloration. Once exposed to AFB 1 , the strong binding occurred between AFB 1 and aptamer induced the separation of Cy5-Apt from the HCeO 2 surface, resulting in the recovery of Cy5-Apt fluorescence and the decrease of HCeO 2 peroxidase-like activity. The sensor exhibited two linear ranges of 0.02–175 ng/mL and 0.05–650 ng/mL. The limit of detection was calculated as 3.39 pg/mL and 10.74 pg/mL, respectively. The mutual verification of the sensor can ensure the reliability and accuracy of AFB 1 detection in food.