A ratiometric fluorescent probe for sensitive detection of anthrax biomarker based on terbium-covalent organic polymer systems

Bacillus anthrax is harmful to humans and animals and can be used as potential biological warfare agents. Dipicolinic acid (DPA) is usually employed to detect Bacillus anthrax as an important biomarker, therefore, it is of great significance to develop highly selective and sensitive DPA quantitative methods. Herein, terbium-covalent organic polymer (Tb-COP) as a ratiometric fluorescent probe was synthesized and applied to quantitatively detect DPA. In the probe, COP played a role of fluorescent reference, while Tb acted as specific recognition element and response signal. When DPA was introduced to Tb-COP, DPA replaced water molecule to coordinate with Tb3+ and transferred the absorbed energy to it, resulting in an "antenna effect". The approach exhibited wide linear range from 0.1 to 30 mu M and low detection limit of 13.5 nM. It was the first time that Tb-COP was used as a ratiometric fluorescent probe for DPA sensing, which provided a non-interference, self-calibration, and effective method for sensitive and selective detection of DPA.