Abstract
Herein, a ratiometric nanoplatform was established for fluorimetric and visual detection of Cu2+ and biothiols based on europium-based metal–organic frameworks (Eu MOFs) and carbon dots (CDs). Fluorescent Eu MOFs with red emission was facilely prepared via the coordination of Eu3+ with tetracycline (TC) and 2-[4-(2-hydroxyethyl)piperazin-1-yl] ethanesulfonic acid (Hepes). However, with addition of Cu2+, the fluorescence of Eu MOFs significantly decreased due to higher affinity of Cu2+ with TC, whereas the green fluorescence of CDs was not influenced by Cu2+, which served as an internal standard of the sensing platform. Interestingly, after introducing biothiols, the stronger coordination between Cu2+ and the sulfydryl of biothiols induced the release of TC to coordinate with Eu3+, thus recovering the fluorescence of Eu MOFs. The ratio changes of these two emissions accompanying by the distinct color variations of the solution under a 365 nm ultraviolet lamp could be used as output signals for fluorimetric and visual detection of Cu2+ and biothiols. The nanoplatform exhibited excellent sensing performance with limit detection as low as 0.57 μM for Cu2+, 0.54 μM for glutathione, 0.14 μM for homocyeteine and 0.42 µM for cysteine, respectively. In addition, it was successfully applied to detecting Cu2+ in environment water samples and biothiols in human serum samples, suggesting great potential for Cu2+ and biothiols determination in environmental and biological samples.
Published Version
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