Rational design of dual-ligand Eu-MOF for ratiometric fluorescence sensing Cu2+ ions in human serum to diagnose Wilson's disease.

Copper levels in body fluids provide an important reference for the diagnosis of Wilson's disease, which associated with blood abnormalities, kidney and cardiovascular disease, and neuropathy. Metal-organic frameworks (MOF) can easily realize dual-emission from single excitation as ratiometric fluorescence sensing and visible detection platform with the intensity ratio of two emissions for simple, rapid, sensitive, and specific analysis of biological samples. Here, we rationally designed a dual-emission Eu-MOF with dual-ligand strategy, denoted as Eu-DATA/BDC. While terephthalic acid (H2BDC) was selected to sensitize Eu3+ ions for the antenna effect emission, 2,5-diaminoterephthalic acid (H2DATA) maintained its own emission and was used to identify Cu2+ ions. Thus, dual-emission from Eu-DATA/BDC and specific recognition of Cu2+ ions were realized for ratiometric sensing of Cu2+ ions. A wide linear concentration range (1-40 μM), low detection limit (0.15 μM), and fast response (less than 10 s) were realized. The color change also achieved the visible detection by naked eye. Copper levels were tested with human serum samples and compared to the ICP-OES results, confirmed the potential of Eu-DATA/BDC probe in the diagnosis of Wilson's disease. The response mechanism to Cu2+ ions was proposed as electron transfer between host and guest for fluorescence quenching. Thus, dual-ligand is a simple and efficient strategy to prepared dual-emission Eu-MOF for the ratiometric sensing and visible detection.