Encapsulation of Dual-Emitting Fluorescent Magnetic Nanoprobe in Metal-Organic Frameworks for Ultrasensitive Ratiometric Detection of Cu2.

An effective dual-emission fluorescent metal-organic framework (MOF)-based nanoprobe has been established for ultrasensitive and rapid ratiometric detection of Cu2+ . Such a nanoprobe was prepared by encapsulating fluorescein isothiocyanate (FITC), and Eu(III) complex-functionalized Fe3 O4 into the zeolitic imidazolate framework material (ZIF-8). In this nanoprobe, FITC was used as a reference signal, thus improving the influence of external uncertainties. The Eu-complex signal could be quenched after adding an amount of Cu2+ . The ZIF-8 could enrich the target analytes, which can amplify the fluorescence signal due to the good adsorption properties of the ZIF-8. Based on above structural and compositional features, the detection limit of the nanoprobe is 0.1 nm for Cu2+ , almost 2×104 times lower than the maximum allowable amount of Cu2+ in drinking water, which constructed a platform for effective detection of Cu2+ . Using the nanoprobe to detect Cu2+ in aqueous solution is rapid and the probe still remained stable. Additionally, this sensor for the ratiometric fluorescence imaging of copper ions was also certified in real samples and live cells.