Ratiometric fluorescent sensor CQDx@Co/Mn-MOF for rapid and sensitive detection of quinolone antibiotics

Quinolone antibiotics pose a threat to health and the environment due to their difficulty in decomposition and misuse. A novel fluorescence composite material CQD_x@Co/Mn-MOF has been developed, which uses cobalt (Co) and manganese (Mn) as metal centers and 1,3,5-triazobenzene as organic ligands. Meaningfully, CQD_x@Co/Mn-MOF can be designed as a ratiometric fluorescence sensor for detecting quinolone antibiotics, especially norfloxacin (NFX). In a series of CQD_x@Co/Mn-MOF, CQD_6μL@Co/Mn-MOF sensor exhibits good linearity within the NFX concentration range of 1-4 × 10^-5 M, with a detection limit of 0.70 μM. Compared with Co/Mn-MOF, introducing CQDs significantly reduces the detection limit from 3.50 μM to 0.70 μM and increases the detection sensitivity by five times. The CQD_6μL@Co/Mn-MOF sensor exhibits fast response time (2 s), high selectivity and sensitivity to NFX, making it an ideal ratiometric fluorescent sensor for the detection of these antibiotics. Based on its excellent detection performance, the sensor was further applied to the quantitative determination of NFX in chicken, beef and honey samples and satisfactory results were obtained with recoveries ranging from 97.51 % to 108.60 %. In addition, based on CQD_6μL@Co/Mn-MOF test strips, convenient and real-time detection of quinolone antibiotics has been achieved. In conclusion, the CQD_6μL@Co/Mn-MOF ratiometric fluorescent sensor provides a reliable, sensitive and efficient analytical method for the detection and evaluation of trace NFX in food, which is of great significance for ensuring food safety and public health.