A magnetic MOFs-based multifunctional molecularly imprinted fluorescence nanosensor for ultra-rapid and sensitive detection of tetracycline in food.

A facile “layer by layer” strategy was used to fabricate core-shell-structured magnetic molecularly imprinted fluorescence encoded microspheres, by integrating a Fe3O4 magnetic core, a ZIF-8 inner-layer, an in-situ grown imprinting shell, and the final encoded quantum dots. This architectural design not only offered the capability of rapid magnetic separation, specific recognition, and sensitive fluorescence response, but also effectively avoided direct contact between the magnetic core and quantum dots, resulting in excellent fluorescence performance. Considering the strong magnetic responsiveness, the obtained microspheres were further employed into magnetic solid phase extraction to selectively capture tetracycline for fluorescence analysis. Under the optimum conditions, the sensor achieved ultra-rapid detection time with 1 min, and exhibited a closely linear relationship (R2 = 0.9941) in the range 3–200 µg L− 1 with a method detection limit of 3 µg L− 1. The spiked recoveries ranged from 83.2% to 112.8% in milk, egg, honey, and pork samples, with RSD value < 7.63%. This work offers an ultra-rapid fluorescence analytical strategy with high accuracy, reliability, and anti-interference capability, and could be considered as an ideal alternative for the rapid detection of various trace contaminants.