One-pot hydrothermal method synthesis carbon dots as a fluorescent sensor for the sensitive and selective detection of clioquinol

Abstract Clioquinol (CQ) is not only used to treat skin diseases, but also CQ is a potential pharmaceutical for the treatment of neurodegenerative diseases. However, only a few researches report the detection of CQ. Thus, it is of great significance to accurately quantify CQ. Herein, we developed a CQ fluorescent sensor by Cu2+ and carbon dots (CDs). Cu2+ adsorbed on the surface of CDs preventing the non-radiative recombination of the holes in the valence band and the excited electrons in the CDs conduction band, which brings about an increase in the fluorescence intensity of CDs. However, a complex is formed owing to the strong affinity with Cu2+ and CQ causing that Cu2+ is disrobed from the CDs surface and then it quenched the fluorescence of CDs through inner filter effect (IFE). The CDs + Cu2+ system displays preferable sensitivity and high selectivity toward CQ in a range of 40.0–400.0 μmol L−1 with a detection limit of 4.7 μmol L−1. In addition, the strategy is employed for the quantification of CQ in clioquinol cream with satisfactory results.