Harnessing MOF on MOF composite for high ratiometric fluorescent tetracycline detection

Tetracycline (TC) compounds, which Metal-organic frameworks (MOFs), a class of porous crystalline materials with designable structures and fluorescence properties, have become ideal candidate materials for constructing ratiometric fluorescent sensors. To enable rapid and convenient detection of tetracycline (TC), we developed a novel CAU-1-on-EuMOF heterostructure, in which EuMOF nanoparticles grow on the surface of blue-emitting CAU-1. This unique architecture achieves efficient dual-emission ratiometric sensing through the synergistic effect of the antenna effect and the inner filter effect, significantly improving selectivity and self-calibration capability. The ratiometric fluorescence sensing platform constructed from this composite material exhibits a limit of detection (LOD) for tetracycline as low as 200 nM. The platform also demonstrated excellent selectivity for TC over other substances. The sensing platform was further tested on real samples, including tap water, milk, and fish. In these tests, the recoveries ranged from 93.53% to 112.07%. These findings highlight the substantial potential of the MOF-on-MOF hybrid material for advanced sensing applications.