Development of a Highly Specific Fluoroimmunoassay for the Detection of Doxycycline Residues in Water Environmental and Animal Tissue Samples

Abstract

Doxycycline (DOX) and its metabolite residues in food and the environment pose a serious threat to human health and the ecological environment. In this work, a novel method, termed competitive fluoroimmunoassays (cFIA), based on monoclonal antibody (mAb) bio-conjugated CdSe/ZnS core–shell quantum dots (QDs), was developed for sensitive and rapid bioanalyses of DOX in natural water and commercial meats. After the optimization of the experimental conditions, 1 μg mL−1 of coating antigen and 0.5 μg mL−1 of QD-labeled mAb were used for the establishment of the cFIA. With this assay, the 50% inhibition concentration was found to be 0.35 ng mL−1 of DOX in phosphate-buffered saline samples, and the limit of detection was 0.039 ng mL−1 with minor cross-reactivity to other tetracycline members. The recoveries from natural water and commercial meats spiked with DOX concentrations of 10–600 ng mL−1 were 81.3–109.8%, and standard deviation were all below 12%. Levels measured with the QD-cFIA for thirty authentic samples were confirmed by high-performance liquid chromatography with good correlations. These results indicate that QD-cFIA is sultable for the rapid and quantitative detection of DOX residue in environmental and food samples.

Editorial for the Special Issue on Quantum Dots Frontiers

“…Thanks to state-of-the-art chemical and device engineering in past decades, we have witnessed more and more novel applications based on semiconductor nanocrystals: quantum dots (QDs). Besides the applications on bio-labeling [ 1 ], QDs have already exhibited great commercial value in lighting applications due to their unique properties compared to traditional technologies. For instance, the emission of QDs is bright, tunable in a visible range, and narrow in bandwidth, enabling high-quality and low-cost lighting including high-color-rendering lights and wide-color-gamut display backlights (known as photoluminescence (PL)-type QD applications) [ 2 , 3 , 4 ].…”

“…Halim et al investigated the electron–phonon coupling mechanism of PbS QDs and PbS/MnTe QDs by tracking their temperature-dependent PL spectra [ 17 ]. For the bio-labeling application, Le et al employed core-shell structured QDs in detecting doxycycline in nature water and in food [ 1 ]. For PL-type QD applications, Xiao et al presented a method to optimize the light quality of white-light LED, in which the QD-based white-light LED is also involved [ 2 ].…”