A water-stable europium-MOF sensor for the selective, sensitive ratiometric fluorescence detection of anthrax biomarker

Sensitive, efficient and rapid detection of 2, 6-pyridinedicarboxylic acid (DPA), commonly labeled as the main biology marker for bacillus anthracis, is of far-reaching consequence to eliminate potential threats. In this work, a 3D Eu-MOF ([Eu(DHBDC) 1.5 (DMF) 2 ]·DMF) that has outstanding thermal and water stability was synthesized. The Eu-MOF showed characteristic fluorescence at 506 nm caused by ligand π-π* transition. The quantum calculation showed that there was a large energy difference between the 5 D 0 level of Eu 3+ and the triplet energy level of 2,5-dihydroxy terephthalic acid ligand (DHBDC 2- ), which was why the coordination compound did not exhibit the characteristic fluorescence of Eu 3+ . Interestingly, it effectively restored the red fluorescence of Eu 3+ (593, 618 and 699 nm) and showed a dual-emission fluorescence response at 506 and 593 nm when the DPA existed. Therefore, based on the high detection sensitivity of Eu-MOF (the detection limit is 1.3 μM) and outstanding anti-interference ability, it is expected to become a prospective ratiometric fluorescence sensor for the detection of DPA. In addition, combined with density functional theory (DFT) and a variety of other analytical methods, the detection mechanism of DPA by Eu-MOF was investigated in detail.