Dual-emission europium metal-organic framework as fluorescent sensor for sensitive detection of anthrax biomarkers

Ratiometric fluorescent sensors, which enable self-referencing quantitative analysis through dual-emission signals, have received significant attention and are widely used in clinical diagnosis, food testing, and environmental monitoring. Herein, a dual-emission europium metal-organic framework (EuMOF) sensor was developed for the sensitive ratiometric fluorescence detection of the anthrax biomarkers, 2,6-pyridinedicarboxylic acid (DPA). EuMOF was synthesized using 2-aminoterephthalic acid (BDC-NH 2 ) and 1,10-phenanthroline (phen) as ligands, with Eu 3+ ions as metal nodes. The EuMOF exhibited dual-emission fluorescence from both the ligands and Eu 3+ ions. Upon DPA addition, the Eu 3+ fluorescence was restored via coordination with carboxyl oxygen atoms, while the ligand fluorescence is quenched, leading to a ratiometric fluorescent response. The sensor displayed high sensitivity, with a detection limit of 330 nM, and excellent selectivity for DPA over other common ions and molecules. As the DPA concentration increased, the fluorescence color shifted from blue to purple-red, enabling visual detection of DPA. Recovery tests using real samples yielded satisfactory results, confirming the practicality of the EuMOF sensor for DPA detection. This study provides a novel, convenient, and sensitive method for detecting anthrax biomarkers, with potential applications in environmental monitoring and biosecurity.