A metal-organic framework/aptamer system as a fluorescent biosensor for determination of aflatoxin B1 in food samples

The demand of simple, sensitive, selective and reliable assay for aflatoxin B1 (AFB1) detection is ubiquitous in food safety, due to its high toxic. Herein, a novel fluorescent aptasensor using metal-organic frameworks (UiO-66-NH₂) and TAMRA label aptamer as sensing platform for AFB1 detection was developed. The TAMRA aptamer adsorbed on the surface of UiO-66-NH₂ via van der Waals force and its fluorescence was quenched for the charge transfer from fluorescence dye TAMRA to metal ions of UiO-66-NH₂. After introducing AFB1 to the system, the TAMRA aptamer binded to AFB1 and formed TAMRA aptamer/AFB1complex, making its conformation change and resulting in fluorescence recovery. Thus, the quantity of AFB1 could be analyzed according to the fluorescence signal change. Under optimize experimental conditions, the assay exhibited high sensitivity toward AFB1 in range of 0-180 ng mL^-1 with low limit of detection of 0.35 ng mL^-1 and good specificity against other toxins. Moreover, the aptamer/metal-organic frameworks sensing platform could be utilized to determine AFB1 content in food samples such as corn, rice and milk. It provided a reasonable method for other mycotoxin detection by changing the sequence of aptamer.