Portable Smartphone Platform Integrated with Fluorescent Test Strip Based on Eu3+-functionalized Copper Nanoclusters for On-Site Visual Recognition of a Pathogenic Biomarker

Abstract 2,6-pyridinedicarboxylic acid (DPA), as unique biomarker of Bacillus anthracis, are highly toxic at trace levels and their pollution has shown great biological threat to homeland security and public safety worldwide. Developing portable and direct read-out devices is an inevitable trend in high demand for reliable point-of-care detection of DPA. We herein report a dual-channel luminescent signal readout probe for sensitive, rapid, and on-the-spot determination of DPA. The developed probe demonstrated a detection limit down to 8 nM was achieved, which is far below the infectious dose of the spores (60 μM). Integrated with the low-cost paper-based sensing devices fabricated by the probe, the smartphone platform installed with a Color Recognition App could accomplish visual DPA detection, which offers a great promise for the point-of-care detection with the merits of low-cost and convenient, thus opening a new pathway for the on-site self-assessment of homeland security and public safety, especially in resource-poor settings. It is believed that the proposed assay could afford experience for designing of smart chemical nose/tongue sensor in hazardous substances monitoring.