Ratiometric fluorescence analysis of tetracycline by dual-ligand europium-based metal-organic framework

Abstract

It is important to develop sensitive and accurate methods for the detection of tetracycline (TC). For this purpose, a dual emission probe Eu-DPA/BDC-(OH)₂ was developed based on the green fluorescence of the ligand 2, 5-dihydroxyterephthalic acid (BDC-(OH)₂), and the red fluorescence of Eu³⁺ sensitized by another ligand 2, 6-pyridine dicarboxylic acid (DPA). TC was able to quench the fluorescence of ligand BDC-(OH)₂ at 545 nm by the internal filter effect (IFE), and coordinate with Eu³⁺ to enhance the fluorescence at 625 nm by the antenna effect (AE). I₆₂₅/I₅₄₅ showed a linear relationship with TC concentration with an LOD at 55 nM. At the same time, the fluorescence color of Eu-DPA/BDC-(OH)₂ changed from green to yellow to red with the increase of TC concentration. On this basis, the RGB method was also developed for the visual detection of TC with an LOD at 0.2 μM. These methods have been successfully applied for the detection of TC in fish feed and pork with recovery rates of 93 % -110 %, indicating excellent applicability in the detection of real samples.