Chitosan-templated copper nanocluster array with reasonable spatial-constraint enabled effective determination of trace fluoroquinolones

Chitosan with different molecular weights (i.e., CS 200 and CS 2 ) as the ligand was employed to stabilize copper nanoclusters (CuNCs), developing a fluorescence “turn-on” probe to recognize fluoroquinolones. Chitosan chains not only can prevent the CuNCs from oxidation and overgrowth, but also provide the regulable luminescence and aggregation-induced emission (AIE) behaviors. The experimental results revealed that the CS 200 @CuNCs probe displayed better sensitivity, selectivity and anti-interference towards ciprofloxacin and several other specific fluoroquinolones than CS 2 @CuNCs. When recognizing the analytes, a more obvious AIE phenomenon occurred in CS 200 @CuNCs. The ciprofloxacin concentration for linear response was 1.0 ~ 180 µM, with a detection limit of 0.067 µM. Moreover, the CS 200 @CuNCs probe could be practically used to determine the ciprofloxacin residue from real samples with good recoveries, implying the perspective in various scenarios. These advantages are attributed to the flexile chain conformation for chitosan in CS 200 @CuNCs, which can generate the reasonable spatial-constraint. This structural feature significantly promotes the recognition and capture of target molecules. This work paves a distinctive way for designing novel biosensors by regulation of the ligand chain length, demonstrating high potential for rapid antibiotic screening. Section Graphical