Luminol-Eu-based ratiometric fluorescence probe for highly selective and visual determination of tetracycline

In this work, a ratiometric fluorometric method based on luminol-Europium complex (luminol-Eu) was constructed for the detection of tetracycline (TC). Luminol-Eu, synthesized by self-assembly reaction, displayed a strongly emission peak at 453 nm under excitation at 360 nm which was derived from the aggregation-induced emission (AIE) of the luminol-Eu. In the present of TC, the fluorescence of luminol-Eu at 453 nm was quenched based on inner filter effect (IFE). Meantime, the characteristic emission peak of Eu³⁺ at 626 nm can be observed thank to antenna effect (AE). Therefore, we proposed a ratiometric fluorometric method for detection of TC, which allowed detection of TC from 0.5 to 80 μM with the detection limit of 39 nM. In addition, the luminol-Eu-based test paper was prepared for visual semi-quantitative detection of TC in real samples based on the color of luminol-Eu change from blue to red under 365 nm ultraviolet light. All of those results indicated that the ratiometric fluorometric strategy was fast, sensitive, and visual for detection of TC.