Yellow and green-emissive N‑containing carbon dots-integrated bio-MOF: A highly sensitive sensing platform for anthrax biomarkers-picolinic and dipicolinic acids

The intentional release of Bacillus anthracis spores through aerosols or contaminated materials poses a serious threat to both individuals and populations. Therefore, it is of utmost importance to develop highly sensitive and rapid techniques for detecting Bacillus anthracis or its biomarkers, picolinic acid (PA) and dipicolinic acid (DPA), to effectively prevent and control potential outbreaks. In this study, we present a promising new approach where green and yellow emissive N‑doped carbon dots (NCDs) are integrated into bio-MOFs enriched with functional groups based on adenine (Ad) and 1,3,5-benzene tricarboxylic acid (BTC) linkers. This integrated system exhibits remarkable stability, high sensitivity, and selectivity, making it an exceptional fluorescent biosensor capable of detecting PA and DPA in a linear range of 5.0 to 140.0 µM and 0.5 to 75.0 µM, respectively. The unprecedentedly low detection limits of 1.65 and 0.16 µM for PA and DPA showcase the sensor's remarkable performance. Through the successful practical application of the sensor, we have been able to rapidly and accurately analyze spiked samples of DPA and PA in urine and water, yielding excellent results and demonstrating the feasibility of this approach. Moreover, our low-cost and user-friendly visual fluorescent sensor enables preliminary qualitative analysis of DPA and PA using the naked eye. The potential of this sensor as a diagnostic system for Anthrax monitoring is highly promising and warrants further exploration for its significant contribution to disease surveillance and control.