Smartphone-based fluorescence sensing platform for tetracycline determination based on a high quantum yield europium metal-organic framework with a dual-ligand strategy.

Ultrasensitive and visual detection of tetracyclines (TCs) is of great significance to public health and environmental safety. Herein, we synthesized a dual-ligand europium metal-organic framework (Eu-phen-MOF) via a one-step solvothermal method for the fluorescence detection of TCs. Compared with the Eu-MOF without 1,10-phenanthroline, Eu-phen-MOF exhibits superior stability, lower LOD and higher quantum yield. It delivers superior TC sensing performance and anti-interference, enabling high-accuracy detection with limits of 152.0 nmol L-1, 249.4 nmol L-1, 171.0 nmol L-1 and 277.7 nmol L-1 for tetracycline (TC), oxytetracycline (OTC), doxycycline hydrochloride (DOX), and chlortetracycline (CTC), respectively. Eu-phen-MOF was used for the quantitative detection of TC, OTC, DOX, and CTC in real samples (milk, eggs, and river water) and recoveries ranging from 94.64% to 105.37% were achieved. Finally, a portable fluorescence sensing platform integrating a smartphone and the Eu-phen-MOF fluorescent hydrogel was constructed, enabling convenient, rapid, and low-cost detection of TCs. This work not only highlights the significance of the dual-ligand strategy for fabricating an efficient TC sensor, but also develops a rapid and visual method for TC detection.