A ratiometric fluorescent probe for determination of the anthrax biomarker 2,6-pyridinedicarboxylic acid based on a terbium(III)- functionalized UIO-67 metal-organic framework

Abstract

Terbium(III)-functionalized zirconium-based MOFs (Tb³⁺@UIO-67) were synthesized by doping Tb³⁺ into UIO-67 using a post-synthetic modification. The Tb³⁺@UIO-67 (solid or aqueous dispersion) shows only blue fluorescence (emission peaks at 420 nm) under an ultraviolet lamp (254 nm). Upon addition of 2,6-pyridinedicarboxylic acid (DPA; an anthrax biomarker), the color of the Tb³⁺@UIO-67 aqueous dispersion under an ultraviolet lamp changes from blue to green. This is mainly because DPA has a good sensitization effect on Tb³⁺. DPA can be determined by measurement of the ratio of the fluorescence intensities at 544 nm and 420 nm (excitation at 278 nm). The method allows DPA to be detected in the 0.3 to 6 μM concentration range, with a detection limit of 36 nM. Graphical abstract Schematic representation of a ratiometric fluorescent probe synthesized by doping terbium ions into a zirconium-based MOF (UIO-67) for determination of an anthrax biomarker.

Keywords: 2,6-Pyridinedicarboxylic acid; Bacillus anthracis spores; Fluorescence; Postsynthesis modification strategy; Zirconium-based MOFs.