Surface decoration of cadmium-sulfide quantum dots with 3-mercaptopropionic acid as a fluorescence probe for determination of ciprofloxacin in real samples

A sensitive fluorescence probe based on 3-mercaptopropionic acid (MPA) capped cadmium-sulfide quantum dots (CdS QDs) was prepared for determination of ciprofloxacin (CIP) in real samples. The synthesized MPA capped CdS QDs was characterized using fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy (TEM) measurements. Based on the results, the fluorescence of MPA capped CdS QDs was quenched in presence of Cu2+ that it could have occurred because of the nonradiative electron-hole recombination annihilation through an electron transfer process. Subsequently, the fluorescence of MPA capped CdS QDs mixed with the Cu2+ could be recovered after the addition of CIP due to its strong affinities for Cu2+. The recovered fluorescence intensity of capped CdS QDs was proportional to the concentration of CIP in the ranges of 0.13-150.0 pinol L-1 and the detection limit was 0.04 mu mol L-1. The established method showed a good selectivity for CIP among several kinds of ions and biomolecules. The fluorescent probe was successfully applied to determine CIP in pharmaceutical preparation and human serum samples. (C) 2016 Elsevier B.V. All rights reserved.