Ratiometric fluorescent sensing for phosphate based on Eu/Ce/UiO-66-(COOH)2 nanoprobe

The sensing of phosphate anion (PO43-) is an important subject for human health and environmental monitoring. Herein, a unique ratiometric fluorescent nanoprobe based on postsynthetic modification of metal-organic frameworks (MOF) UiO-66-(COOH)(2) with Eu3+ and Ce3+ ions toward PO43- was proposed (designated as Eu/Ce/Uio-66-(COOH)(2)). The Eu/Ce/Uio-66-(COOH)(2) nanoprobe exhibits three emission peaks at 377 nm, 509 nm, and 621 nm with the single excitation wavelength at 250 nm, respectively. The strong coordinating interaction between Ce3+ and O atoms in the PO43- group can result in the fluorescence quenching at 377 nm, while the fluorescence of 621 nm almost remains unchanged. Such a useful phenomenon is exploited for the construction of a ratiometric fluorescence platform for the detection of PO43-. The assay exhibited a good linear response in the 0.3-20 mu M concentration range with the detection limit of 0.247 mu M. In addition, this ratiometric fluorescent sensing method not only can be applied to read out PO43- concentration in real water samples, but also shows higher sensitivity, easier preparation and sensing procedures than other detection strategies. (C) 2021 Elsevier B.V. All rights reserved.