Copper nanoclusters as a turn-on fluorescent probe for sensitive and selective detection of quinolones

• Ratio fluorescent nanoprobe for Fe 3+ -based quinolones detection was established. • The response to quinolones is based on fluorescence “turn-on” sensor. • This sensing system has good sensitivity and selectivity to quinolones. • This probe was applied to detect quinolones in tablets and human urine. As a new type of fluorescent probe, metal nanoclusters have a broad application prospect in optical sensors and biosensors. In the present study, copper nanoclusters (CuNCs) have been synthesized by etching non-luminescent copper nanoparticles with excess cysteine (Cys). The as-prepared cysteine stabilized turquoise emitting copper nanocluster (Cys-CuNCs) exhibited strong fluorescence emission, and could be quenched by Fe 3+ ions. After adding quinolones (QNs) to the quenching system, the fluorescence intensity of Cys-CuNCs was restored. A novel Cys-CuNCs-Fe 3+ sensor for the detection of QNs, such as ofloxacin (OFL) and norfloxacin (NOR), was constructed based on the fluorescence turn-on strategy. The linear range of the proposed method is 0.5–40 μM for OFL and 0.5–50 μM for NOR, and the detection limits of OFL and NOR are all 50 nM. As a cost-effective, high selectivity and sensitivity sensor tool, the Cys-CuNCs-Fe 3+ sensor had been successfully applied to detect QNs in tablets and human urine.