MoB QDs/N, F-CDs for ratiometric fluorescence sensing of perfluorooctanoic acid based on fluorine‑fluorine...

A dual-emission ratiometric fluorescence probe was constructed for detection of perfluorooctanoic acid (PFOA) by hybridizing MoB quantum dots (MoB QDs) and nitrogen, fluorine co-doped carbon dots (N, F-CDs). As the concentration of PFOA increased, the fluorescence emission of MoB QDs/N, F-CDs at 560 nm was quenched due to fluorine-fluorine interaction, while the fluorescence emission at 440 nm kept unchanged, resulting in the fluorescence color changing from yellow to green. A good linear relationship was observed between I₄₄₀/I₅₆₀ and the concentration of PFOA in the range 0.01-90 μM and 90-450 μM, with a detection limit as low as 0.01 μM. The test strips for PFOA were prepared for on-site visualization and quantitative determination. The fluorescence images of the test strips were acquired using the camera in the smartphone, and the signals were converted into RGB values by color recognition software. The obtained G/R value had a good linear relationship with the concentration of PFOA ranging from 0.5 to 200 μM. The deep learning model of YOLOv5 algorithm was utilized for data analysis to make the fluorescence detection more accurate. Therefore, the ratiometric fluorescence sensing system is established with easy operation, short response time, and low cost for on-site detection of PFOA in real water samples and textiles, which is of practical significance for environmental water monitoring and human health.