Fast fluorescence sensing of aflatoxin B1 employing a europium metal–organic framework avoiding self-fluorescence interference of target

Aflatoxin B1 (AFB1) easily contaminates grain, oil, and their products, and is strongly carcinogenic. Therefore, rapid, efficient and sensitive detection of aflatoxin plays a key role in the food industry. Here, we prepared a lanthanide metal-organic framework termed Eu-TCPP, in which the ligand can effectively sensitize Eu3+ with excellent photoluminescence properties. It is worth mentioning that the fluorescence intensity of Eu-TCPP is at 617 nm, which can avoid the interferences of AFB1 self-fluorescence emitting in the range of 400 nm–500 nm. Eu-TCPP can efficiently detect AFB1 without using antibody or biomolecular modifications, exhibiting a rapid response of 60 seconds and a limit of detection (LOD) at 11.63 ppb. The Eu-TCPP sensor also has satisfactory performance for determining AFB1 sensitively in real oil samples. In addition, the mechanism of the excellent detection performance of Eu-TCPP has been investigated using density-functional theory (DFT) calculations combined with experimental analysis. The results show that the LUMO energy level of the ligand is higher than that of the aflatoxin, which causes the electrons transfer toward the targets, and results in the reduction of the fluorescence intensity. Therefore, our proposed Eu-MOF materials based on the "antenna effect" have great potential for the development of simple, fast, and sensitive small-molecule sensors, and offer a promising prospect in POCT applications.