Carbon dot-ZIF-67-infused tragacanth hydrogel films: leveraging tunable luminescence through displacement mechanisms for anthrax detection.

A novel method for 2,6-Pyridine dicarboxylic acid (DPA) detection is introduced using red emissive carbon dots (r-CDs) derived from amaranth leaves and Eosin Yellow (EY), encapsulated within a Co-based MOF (ZIF-67). The approach utilizes ratiometric turn-on fluorescence and visual identification of DPA through a displacement assay, where the release of EY enhances its fluorescence intensity, while the fluorescence of r-CDs remains constant. The sensing platform demonstrates a wide detection range (10.0-280.0 μM) with limits of detection of 1.7 μM and 3.3 μM. The probe offers notable advantages, including simple preparation, high yield, stability, selectivity, and rapid detection. Additionally, a composite functional hydrogel, made from Tragacanth (TG), was developed for DPA detection in real samples (tap water and urine), showcasing excellent performance. Integration with smartphone-based on-site signal recording enables clear fluorescence visual changes, highlighting the potential for practical applications. This study presents an innovative r-CDs/EY-ZIF-67-based hydrogel film for fluorescence sensing of DPA, expanding the scope of high-performance fluorescent materials for anthrax monitoring and real-world applications.