Fabrication of Dual-Ligand Zn-MOFs with Asynchronous Fluorescence Response for Efficient Ratiometric/Visual Sensing of Tetracycline Antibiotics in Animal-Derived Foods

The extensive use of tetracyclines in livestock poses health risks due to their residues in animal-derived food; therefore, developing simple detection methods to replace complex traditional approaches is of paramount importance. Here, we developed a dual-ligand zinc-based metal-organic framework material, Zn-BTC-BDC-NH₂ (denoted as ZTD), for the detection of tetracyclines. The intrinsic blue fluorescence of ZTD was quenched upon the introduction of tetracyclines due to electron transfer from -NH₂ of ZTD to -CO- and -OH groups of tetracycline molecules; meanwhile, the new green fluorescence emission was generated through π-π stacking between aromatic rings and the formation of complexes between Zn²⁺ and C-O/C═O groups. In real food samples, ZTD exhibited recovery rates ranging from 93.62 to 110.66%, with detection limits as low as 0.011 μmol·L^-1. Additionally, a ZTD fluorescence test paper was developed for portable detection. This study presents a novel tetracycline detection method, offering insights into multiligand metal-organic framework preparation and future sensing method design.