A J-Aggregating Cyanine-Based NIR-II Optical Sensor for DNA Aptamer-Mediated Detection and Imaging of Quinine

We report a dye-displacement assay for quinine detection integrating a DNA aptamer with a J-aggregating NIR-II cyanine dye. This platform achieves sensitive, selective, and label-free NIR-II colorimetric and fluorescence sensing, with a fluorescence-based detection limit as low as 0.014 μM in urine solution, and enables NIR-II fluorescence imaging.