Integrating peroxidase-mimicking NH2-MIL-101(Fe) with molecular imprinting for high-performance ratiometric fluorescence sensing of domoic acid

Ingestion of shellfish and water containing excessive domoic acid (DA) threatens human health tremendously, and even causes death in severe cases. Herein, we have integrated the bifunctional NH2-MIL-101(Fe) with molecular imprinting to design a ratiometric fluorescent sensor for quantitative analysis of DA. In this research, NH2-MIL-101(Fe) itself can supply an intrinsic peak at 452 nm, and trigger oxidation of o-phenylenediamine (OPD) to 2,3-diaminophenazine (DAP) with peak at 556 nm owing to its excellent peroxidase-like activity. The two signal probes that influence each other owing to the inner filter effect (IFE) can form a highly sensitive composite fluorescent probe. Additionally, the introduction of molecular imprinting technology (MIT) instead of expensive antibodies can endow the ratiometric fluorescent sensor outstanding selectivity and specificity toward DA. Thus, the proposed ratiometric fluorescent sensor exhibits outstanding sensitivity, super anti-interference ability, and excellent selectivity. The experimental results demonstrate that the sensor exhibits good performance for DA sensing in the scope of 0.01–10 μM with low limit of detection (LOD) as 8.2 nM. More attractively, the successful spike and recovery experiments in real samples with the complicated matrix indicate the considerable practical application promise of our proposed ratiometric fluorescent sensor.