A Novel Cucurbit[8]uril 2:2 Supramolecular Complex for Fluorescence Sensing of Gentamicin in Milk

Since antibiotics abuse has brought the severe threat to ecosystem and human health, the monitoring of antibiotics in the environment is drawing increased interest. In this work, a rare 2:2 supramolecular host-guest complex (12@Q[8]2) was successfully constructed by encapsulating the guest molecule 1,4-bis(2-benzimidazol-2-yl) benzene (1) into the cavity of cucurbit[8]uril (Q[8]). It was found that the fluorescence of (1) was quenched significantly upon the formation of host-guest system and then could be selectively recovered in the presence of gentamicin (GEN) owing to the displacement of guest molecules. Fluorescence titration experiments indicated that the formed supramolecular complex 12@Q[8]2 could function as a quantitative fluorescence sensor for GEN in the low concentration range with the limit of detection (LOD) of 0.17 μM. Furthermore, 12@Q[8]2 also showed excellent practicability and reliability for the detection of GEN in milk samples.