Ratiometric fluorescence detection of 2,6-pyridine dicarboxylic acid with a dual-emitting lanthanide metal-organic framework (MOF)

Abstract

Bacillus anthracis is an extremely dangerous bacterium with high morbidity and mortality. It is thus of great importance to detect Bacillus anthracis or its major biomarker 2,6-pyridine dicarboxylic acid (DPA) in a rapid and sensitive way. Althought metal-organic frameworks (MOFs) have found great applications in catalysis and sensing; nevertheless, there are only a few fluorescent MOFs can be used in DAP detections, and the key factors determining the detection sensitivity is not clear yet. In this study, we successfully synthesized a novel nano-sized dual-emitting lanthanide MOF, namely Eu/Tb(BTC), for the high-sensitivity DPA detection. The synthesized Eu/Tb(BTC) showed a remarkable sensitivity, excellent selectivity, and a high accuracy. Through comprehensive characterizations of the microstructure, luminescence properties, and sensing performance of products with different Eu/Tb ratios, the unique capability as a sensitive fluorescent probe (limit of detection 1087 nM) for selectively detecting DPA was demonstrated. More importantly, a possible route to control the sensitivity of detection by controlling the original energy transfer efficiency between Eu3+ and Tb3+ was revealed. This work not only provides an excellent nano-probe for qualitative and quantitative detection of biomarker of Bacillus anthracis, but also reveals an important rule for improving the sensitivity of sensing systems.