A novel spectral approach for minocycline and doxycycline monitoring using ZIF-8 modified CdS@ZnS quantum dot hybrid nanocomposites

Abstract

At present, the application range of tetracycline (TCs) is very wide, and excessive residue will pose a threat to the health of consumers. However, there is a lack of methods more suitable for on-site detection. In order to ensure food safety, CdS@ZnS QDs and zeolitic imidazolate framework-8 (ZIF-8) were hybrid to obtain the composite CdS@ZnS QDs@ZIF-8, which was used as fluorescent probe to establish real-time methods for the detection of minocycline (MC) and doxycycline (DC). The quantum yield (QY) of the prepared composite CdS@ZnS QDs@ZIF-8 was 20.76 %. The MC/DC quenched the fluorescence of CdS@ZnS QDs@ZIF-8 in a static manner, which was confirmed by Stern-Volmer and time-resolved fluorescence analysis. The binding constant at 293 K was obtained and electrostatic force was found to play a leading role in the two binding processes. The optimal pH, contact time and temperature for the determinations were obtained. The interferences of some common metal ions, glucose, BSA, DNA, HSA and tryptophan on the detections were investigated. The linear relationship between the concentration of MC/DC and the fluorescence intensity ratio was established. The limits of detection (LODs) were 10.06 and 11.24 ng mL⁻¹ (3S₀/S) for MC and DC. The methods were successfully applied to the detection of MC and DC in egg samples with good recovery and precision.