Eu3+-MOF fluorescence sensor based on a dual-ligand strategy for visualised detection of an anthrax biomarker 2,6-pyridine dicarboxylic acid

Abstract

Bacillus anthracis is an extremely dangerous bacterium that causes high morbidity and mortality. Developing a simple and effective sensor to detect its unique biomarker 2,6-pyridine dicarboxylic acid (DPA) is urgently required to prevent anthrax infection. In this work, a ratiometric fluorescence sensor based on lanthanide–metal–organic frameworks (MOFs) was developed for the sensitive and selective recognition of DPA. Eu-MOF was successfully synthesised by Eu³⁺, 2,5-thiophenedicarboxylic acid, 2-aminoterephthalic acid, and dimethylformamide (DMF) through a simple solvothermal method. The rationally designed Eu-MOF not only exhibited outstanding sensitivity, strong stability and excellent anti-interference ability for DPA detection but also realised an obvious naked-eye colour change from red to blue with the increasing DPA concentration under UV light. Moreover, a possible detection mechanism involving hydrogen bonding, coordination and photoinduced electron transfer between the Eu-MOF and DPA was proposed. More importantly, the application of Eu-MOF probes in fetal calf serum and tap water also obtained satisfactory results, and the Eu-MOF probes were immobolised onto polyvinyl alcohol membrane, achieving a portable and convenient approach to monitoring DPA.