A water-stabilized Tb-MOF can be used as a sensitive and selective fluorescence sensor for the detection of oxytetracycline hydrochloride.

Oxytetracycline hydrochloride (OTC) is a commonly used over-the-counter antibiotic, valued for its potent antibacterial properties. However, the inappropriate and excessive use of OTC can result in the accumulation of the drug in both the environment and human body, causing significant harm to ecosystems and human health. Therefore, the development of a fast and sensitive method for detecting OTC is of great significance. Lanthanide metal-organic frameworks (LnMOFs) can effectively excite lanthanide metals to emit long-lifetime, narrow and stable fluorescence based on the antenna effect, but their application in fluorescence sensing is rarely reported. In this work, a strongly fluorescent material Tb-MOF was synthesized by a facile solvothermal method using 1,2,4,5-phenylenetetracarboxylic acid (H₄btec) and 1,10-phenanthroline (1,10-phen) as organic ligands and lanthanide metal Tb as the luminescent center. Tb-MOF is a stable material in water and shows excellent linearity with OTC in the concentration range of 0 ∼ 70 μM, with low detection limit (0.12 μM) and luminescence color transition from bright green to dark green during the detection process. X-ray diffraction, UV-vis absorption and fluorescence lifetime analyses revealed that the fluorescence quenching of Tb-MOF by OTC is caused by the inner filter effect in static quenching. Test strips for OTC detection were successfully prepared using Tb-MOF. These strips are not only low cost and easy to prepare but can also be used as portable sensing devices that can be easily distinguished by the naked eye during OTC testing. This study not only presents a fluorescent probe for the detection of OTC in water but also offers a practical method for converting fluorescent luminescent materials into functional devices for OTC detection.