A dual-functional fluorescence probe CDs@ZIF-90 for highly specific detection of Al and Hg in environmental water samples.

In recent years, the escalating water pollution has resulted in serious harm to human health and ecological environment due to the excessive discharge of toxic metal ions such as Al and Hg. Therefore, it is crucial to develop a simple, efficient, and rapid detection method for monitoring the levels of the metal ions in water environment to ensure public health and ecological safety. In this study, carbon dots (CDs) containing heteroatom Si were successfully synthesized by the solvothermal method. Subsequently, a novel dual-functional fluorescent sensor (CDs@ZIF-90) was constructed by integrating CDs with zeolitic imidazolate framework-90 (ZIF-90). The fluorescent composite CDs@ZIF-90 showed outstanding optical properties and excellent structural and luminescence stability in aqueous medium. Particularly, its fluorescence at 453 nm can be remarkably enhanced by Al and quenched upon exposure to Hg. As a result, the CDs@ZIF-90 was applied in sensitive and selective determination of Al and Hg ions with wide linear ranges (1-200 μM and 0.05-240 μM) and low detection limits (0.81 μM and 19.6 nM). Moreover, a convenient and rapid fluorescence test strip was also successfully prepared for visual detection of Al and Hg ions. This work is the first try to use the CDs@ZIF-90 fluorescence sensing material for highly sensitive and selective determination of Al and Hg based on "turn-on" and "turn-off" dual modes, respectively and it provides a new idea for monitoring quality of drinking water and environmental water. It is of great significance for human health and environmental protection.