Ratiometric fluorescence determination of the anthrax biomarker 2,6-dipicolinic acid using a Eu3+/Tb3+-doped nickel coordination polymer†
Tb3+/Eu3+@Ni-BTC (H3BTC = 1,3,5-benzenetricarboxylic acid) composites were prepared by soaking the Ni-BTC parent framework in Tb3+ and Eu3+ ethanol solutions. Various factors were optimized, with the ratio of Tb3+ : Eu3+at 6 : 4, the soaking time being 30 h, and the MOF dosage being 100 μg. The sensitivity tests of DPA detection by the optimized Tb3+0.6/Eu3+0.4@Ni-BTC indicated a linear relationship of I545/I613 = 1.24098·CDPA + 3.80396 where CDPA = 2–20 μmol L−1, and the limit of detection was calculated as 14.7 nM. Tb3+0.6/Eu3+0.4@Ni-BTC exhibited high selectivity without interference from seven interferents. The detection mechanism is inferred as that DPA sensitizes Tb3+ and transfers energy to Eu3+, however it blocks the energy transfer from HBTC2− to Eu3+. Tb3+0.6/Eu3+0.4@Ni-BTC can be regarded as a potential candidate for a quantitative ratiometric fluorescence sensor for DPA detection with high sensitivity and selectivity.