An ingenious integrated metal-organic frameworks-based ratiometric sensing platform for efficient, sensitive and real-time detection of tetracyclines

Herein, we report a novel ratiometric nanoprobe (CDs@LZIF-8-Eu³⁺) that integrates fluorescent carbon dots (CDs) and Eu³⁺ on LZIF-8 via a one-pot stirring method. Tetracyclines (TCs) can create inner filter effect on CDs while simultaneously generating an antenna effect with Eu³⁺. The rapid and efficient adsorption capabilities of LZIF-8 enhance the probability of TCs interacting with the signal tags. Additionally, energy transfer between CDs and Eu³⁺ linked by LZIF-8, sensitizes the fluorescence changes, resulting in signal amplification. The nanoprobe exhibits reverse response signals with high sensitivity (2.94–4.46 ng/mL), rapid response (within 10 s), and visible color change (blue to red). The practicability of the CDs@LZIF-8-Eu³⁺ nanoprobe was demonstrated in food and environmental samples, accurately discriminating four TCs through principal component analysis. Furthermore, the first portable nanofibers mat based solid-phase fluorescence sensing platform was fabricated by an in-situ growth method. Combined with a smartphone-assisted device, rapid on-site monitoring of TCs can be achieved.