Ultrasensitive turn-off fluorescence detection of iodide using carbon dots/gold nanocluster as fluorescent nanoprobe

In this work, a novel fluorescence turn-off sensing strategy for I− ions detection was developed. The fluorescence of CDs/His-AuNCs hybrid probes was effectively turned off by I− ions. It was attributed to the internal filtration effect between the fluorescence emission peak of CDs and the absorption spectrum of His-AuNCs enhanced by I− ions. Quantitative analysis of I− ions can be achieved by analyzing the fluorescence quenching degree of CDs/His-AuNCs. Under the optimal experimental conditions, it exhibited good linearity in two concentration ranges of I− ions: 0.1–5.0 μM and 5.0–60.0 μM (low detection limit = 34 nM). The established sensing platform has been successfully exploited for the detection of I− ions in practical water samples. This work provided new insight into the determination of anions using fluorescent nanoparticles.