Carbon Dot/Gold Nanocluster-Based Fluorescent Colorimetric Paper Strips for Quantitative Detection of Iodide Ions in Urine

Abnormal amounts of small molecules in biological systems such as iodide ions (I–) might be the critical presage of some diseases and hazardous to human somatic function and played an important role in many physiological activities of humans. Herein, we developed a carbon dot/gold nanocluster-based fluorescent colorimetric paper strip, enabling visual quantitative detection of iodide ions in urine for health evaluation. The nanoprobe was designed by mixing cyan carbon dots and red functionalized gold nanoclusters with the aid of mercury ions (Hg2+). The quenched fluorescence can be quickly recovered after the interaction with iodide ions (I–), showing a significant color change from green to yellow to orange. Consequently, the fluorescent nanoprobe solution and corresponding paper strip can realize the visual detection of iodide ions in urine, with detection limits of 0.70 and 2.0 μM, respectively. The proposed strategy could extend to trace a variety of biomolecules under real-time/on-site conditions based on family medical monitoring to perform timely health screening.