development of carbon quantum dot–labeled antibody fluorescence immunoassays for the detection of morphine in hot pot soup base

Morphine is the most representative characteristic alkaloid existed in the extract solution of poppy shell. the analysis of morphine can be used to judge whether poppy shell is illegally added to the hot pot soup base. a sensitive, environmental-friendly carbon quantum dots (c-dots)–based fluorescence immunoassay (c-dots-flisa) was developed to detect morphine (mop). novel water-soluble c-dots were synthesized using a one-step hydrothermal reaction, with citric acid serving as the carbon source and ethylene diamine acting as the nitrogen source. moreover, the c-dots displayed blue fluorescence with an emission peak at 440 nm (350 nm excitation), which also showed good stability. c-dots which contained amine were used to conjugate with anti-morphine antibody by glutaraldehyde as coupling reagents. the anti-morphine antibody–labeled c-dots (abs-labeled c-dots) were characterized by fluorescence spectrum, transmission electron microscopy (tem), and gel electrophoresis. c-dots-flisa was developed and applied to quantitative detection of morphine. under the optimal conditions, the linear range spanned from 3.2 × 10−4 to 10 mg/l (r2 = 0.992), and the detection limit was 3 × 10−4 mg/l. these results demonstrated that the developed c-dots-flisa could be applied as a sensitive and convenient tool for rapid detection of morphine.