A europium (III) functionalized hydrogen-bonded organic framework for sensitively ratiometric fluorescent sensing of tetracycline.

As a kind of antibiotic, tetracycline (TC) might remain in animal blood and milk products during use, which poses a risk to humans after consumption. Therefore, a ratiometric fluorescence probe was proposed for the detection of TC, which was based on an Eu functionalized hydrogen-bonded organic framework (HOF). Since there are a large number of N and O atoms in the skeleton of HOF, more Eu could be loaded onto HOF by forming coordinate bonds, while preserving the fluorescence of luminol monomer in HOF. In the presence of TC, the fluorescence of luminol monomer was attenuated at 425 nm due to inner filter effect (IFE), while TC selectively enhanced the fluorescence peak at 617 nm of Eu under the influence of antenna effect (AE). This highly sensitive probe could detect TC in the range of 0.1-60 μM and had a low limit of detection of 8.51 nM. Besides, the HOF@Eu probe was able to detect TC in actual samples (milk and tap water) with good recoveries (95.09%-111.51%) and precision (R < 4.78%), indicating this probe has great application potential for the detection of TC in food.