COF@Eu-based ratiometric fluorescent sensor for sensitive detection of an anthrax biomarker dipicolinic acid

Anthrax is a serious zoonotic disease caused by Bacillus anthracis and dipicolinic acid (DPA) is the key component and major biomarker of Bacillus anthracis, therefore the development of rapid and sensitive DPA detection method is crucial to ensure public safety. In present study, carboxyl-functionalized covalent organic framework TpPa-COOH was synthesized using 2,5-diaminobenzoic acid and 2,4,6-triformylphloroglucinol as the building blocks, then Eu 3+ was immobilized onto TpPa-COOH via coordination interaction to give the fluorescent composite TpPa-COOH@Eu 3+ of dual-emissions. The presence of DPA significantly enhanced the characteristic emission of TpPa-COOH@Eu 3+ at 616 nm attributed by the “antenna effect” between DPA and Eu 3+ , thus a ratiometric fluorescent sensor was developed for the sensitive DPA detection with a detection limit of 9.5 nmol L −1 . The ratiometric fluorescent sensor offered DPA detection with high accuracy and favorable selectivity. The practicability of fluorescence sensor was validated by detecting DPA contents in real water samples. This research not only proposes a sensitive fluorescence method for anthrax biomarker detection, aiding in the prevention of biological threats and disease spread, but also highlights the potential of COFs in developing efficient ratiometric fluorescent probes with self-calibration capabilities.