A ratiometric fluorescent paper-based sensor based on Fe/Eu-MOF for visual and sensitive detection of...

Diethylstilbestrol (DES), a synthetic estrogen, is associated with severe endocrine disruption and carcinogenic risks, posing persistent biological and environmental hazards. Herein, a bimetallic Fe/Eu-based metal-organic framework (Fe/Eu-MOF) with distinct multi-emission properties was developed as a ratiometric fluorescent sensor for sensitive and intelligent visual detection of DES. The Fe/Eu-MOF exhibited stable red emission at 615 nm and DES-responsive blue emission at 410 nm, enabling self-referenced quantification. The sensor showed two linear ranges (0.005-2 and 2-30 μg/mL), a low detection limit (1.78 ng/mL), and excellent selectivity against potential interferents. Its practicality was validated in milk and shrimp, demonstrating excellent recovery and reproducibility. Additionally, a paper-based sensor integrated with smartphone RGB analysis enabled rapid, on-site, and instrument-free detection. Mechanism studies revealed that DES coordination with Fe centers suppressed non-radiative decay and enhanced fluorescence. This work provides a robust and intelligent platform for portable monitoring of DES residues, offering significant potential for real-time biohazard surveillance and visual diagnostics in resource-limited settings.