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

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 mu g mL(-1) of coating antigen and 0.5 mu g 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.

Automated summary

A novel method based on quantum dots has been developed for sensitive and rapid detection of DOX residue in natural water and commercial meats. The method showed high accuracy and reliability, making it suitable for rapid quantitative analysis in environmental and food samples.