Fluorometric and smartphone-based dual-mode sensor for tetracyclines by bimetallic Fe/Eu-MOFs nanocomposite in foods.

The overuse of antibiotics has caused significant accumulation of tetracyclines (TCs) residues in the food chain, posing serious health risks. A europium- and iron-co-doped metal-organic framework (Fe/Eu-MOFs) was synthesized using a one-pot hydrothermal strategy. The Fe/Eu-MOFs demonstrate intense red fluorescence emission at 615 nm, which undergoes quenching upon the introduction of TCs. This phenomenon facilitates the selective detection of tetracycline (TC), oxytetracycline (OTC), and doxycycline (DOX), the limit of detection (LOD) values was determined to be 0.052, 0.047, and 0.062 μg/mL, respectively. The sensor exhibits exceptional selectivity and reproducibility in real matrices (milk, honey, Yellow River water), achieving 93.9%-109.5% recovery rates. Integration with smartphone-based RGB analysis allows visual online detection, enhancing field applicability. Mechanistic investigations indicate that fluorescence quenching arises from the synergistic interplay between IFE and PET. This work provides a simple, cost-effective synthesis strategy for Fe/Eu-MOFs and establishes an ultrasensitive sensing platform for TCs in complex systems.