Enhanced fluorescence of mercaptopropionic acid-capped zinc sulfide quantum dots with moxifloxacin in food and water samples via reductive photoinduced electron transfer†
Fluorescence is a promising technique adopted in a large number of optical sensing probes. In this study, a facile and rapid fluorometric 3-mercaptopropionic acid-capped zinc sulfide (MZnS) quantum dot (QD)-based nanosensor is reported for the specific detection of moxifloxacin (MOXI). Trioctylphosphine-capped ZnS (TOP-ZnS) QDs were synthesized by a hot injection method followed by a ligand exchange process to make water-soluble MZnS QDs suitable for biological applications. Transmission electron microscopic analysis exhibited monodisperse TOP-ZnS and MZnSQDs with average sizes of 2.11 ± 1.47 nm and 2.52 ± 0.89 nm, respectively with excitation wavelength dependent blue fluorescence (FL) emission property. Under optimum conditions, the FL intensity of QDs enhanced 41.3-fold with MOXI concentrations due to the reductive photoinduced electron transfer (PET) mechanism. With the developed nanosensor, MOXI can be quantified in a 1–100 μM concentration range with a lower detection limit of 0.203 μM. The proposed nanosensor was successfully applied to determine MOXI in real samples and can potentially be used in environmental and food safety applications.