A ratiometric fluorescent nanoprobe based on ZIF-8@AuNCs-Tb for visual detection of 2,6-pyridinedicarboxylic acid

Abstract The rapid and sensitive detection of 2,6-pyridinedicarboxylic acid (DPA), one of the main biomarkers of Bacillus anthracis, is of great significance for the screening and diagnosing of anthrax. Herein, a ratiometric fluorescent nanoprobe based on zeolite imidazolate framework-8 (ZIF-8)@AuNCs-Tb was constructed by embedding both gold nanoclusters (AuNCs) and terbium ions (Tb3+) into ZIF-8 for high-resolution visual detection of DPA. Due to the aggregation induced emission enhancement (AIE) effect, AuNCs embedded in ZIF-8 emit a strong orange fluorescence. When Tb3+ is coordinated with DPA added to the nanoprobe, it will emit a strong green fluorescence owing to the antenna effect. The results reveal that ZIF-8@AuNCs-Tb nanoprobe can detect DPA effectively with a good linear relationship in the range of 40–200 and 200–1000 μmol/L, the limit of detection (LOD) is estimated at 1.8 μmol/L (3σ/k). The proposed nanoprobe shows a remarkable selectivity for DPA and is quite easy to realize visualization based on the fluorescent color changing from orange to green, which has potential application in clinical diagnosis. The feasibility of this method was verified by standard addition recovery experiments simulating the release of DPA from spores.