Development of Quantum Dots-Labeled Antibody Fluorescence Immunoassays for the Detection of Morphine

Quantum dots (QDs)-labeled antibody fluorescence immunoassays (FLISA) for the detection of morphine were developed. Quantum dots (CdSe/ZnS), which contained carboxyl, were used to label antimorphine antibody by 1-ethyl-3-(3-dimethylaminoprophyl) carbodiimide hydrochloride/N-hydroxysulfosuccinimide, which were used as coupling reagents. The CdSe/ZnS QDs labeled antimorphine antibody (QDs labeled Ab) was characterized by fluorescence spectrum and gel electrophoresis. Plate-based FLISA and nitrocellulose membrane-based flow-through FLISA were developed and applied to quantitative and qualitative detection of morphine. Under the optimal conditions for plate-based FLISA, the linear range spanned from 3.2 × 10^-4 to 1 mg/L (R² = 0.9905), and the detection limit was 2.7 × 10^-4 mg/L. The visual detection limit for morphine by membrane-based flow-through FLISA was 0.01 mg/L. These results demonstrated that the developed fluorescence immunoassays could be applied as highly sensitive and convenient tools for rapid detection of morphine, which make it ideally suited for on-site screening of poppy shell added illegally in hot pot soup base.