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

A novel fluorescence turn-off sensing strategy for I− ions detection was developed based on the internal filtering effect between CDs and iodide-induced aggregation His-AuNCs. [Display omitted] • An ultrasensitive sensing strategy for iodide detection was proposed. • His-AuNCs and iodide form ground-state complexes that block the CDs' fluorescence. • A new insight into I− ions determination with CDs/His-AuNCs is presented. 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. [ABSTRACT FROM AUTHOR]