Ultrasensitive ciprofloxacin assay based on the use of a fluorescently labeled aptamer and a nanocomposite prepared from carbon nanotubes and MoSe2.

A nanocomposite was prepared from carbon nanotubes and MoSe2 (CNT-MoSe2). This nanomaterial quenches the fluorescence of fluorescein-labeled aptamers. When ciprofloxacin (CIP) binds to the aptamer, an aptamer/G-quadruplex complex will be formed and the interaction between labeled aptamer and CNT-MoSe2 nanostructures is weakened. This leads to significant fluorescence recovery. Under optimized experimental conditions, the limit of detection is 0.63 ng mL-1 with a good linearity in the range from 0.63 to 80 ng mL-1. The assay was applied to the determination of CIP in spiked milk, and the recoveries range between 94.3 and 97.0% (n = 3). Conceivably, the method is a generic approach that can be extended to the determination of other analyte for which adequate aptamers are available. Graphical abstract Schematic presentation of CNT-MoSe2 quenching based aptamer assay for the detection of ciprofloxacin. The assay exhibits good selectivity, stability and reproducibility, and low limit of detection.