Phosphate-Modulated Luminol-Tb Fluorescent Probe for the Ratiometric Detection of Anthrax Biomarker

Abstract

Achieving sensitive and selective detection of Bacillus anthracis is of great significance for preventing anthrax infection. This work constructs a Luminol-Tb fluorescent complex based on phosphate (Pi) regulation (Luminol-Tb-Pi) for the rapid, sensitive, and visual detection of anthrax bio-marker (2,6-pyridyldicarboxylic acid, DPA). U nder the regulation of Pi, with Luminol as the organic ligand and Tb 3+ as the central ion, DPA can significantly enhance the characteristic fluorescence of Tb 3+ and cause quenching of Luminol. DPA acts as the antenna ligand of Tb 3+ to sensitize its luminescence, and Pi enhances the sensitization of DPA by reducing the distan ce between DPA and Tb 3+ . In addition, the coordination of Pi with Tb 3+ can reduce the quenching effect by water molecules, further enhancing Tb 3+ fluorescence. Due to the competitive binding between DPA and Tb 3+ , the coordination between Luminol and Tb 3+ i s weakened, and some Luminol become free, leading to their fluorescence quenching. Based on the dual fluorescence signal, the ratiometric detection of DPA is achieved with a quantitative range of 0.2 ~ 45 μM. In addition, the visual dete c-tion of DPA can be achieved based on the fluorescence color change of this sensing system. The sensing method developed is simple, low cost, and possesses potential in actual applications.