Time-resolved fluorescence immunoassay for detection of CEA in saliva

Abstract

To establish a real-time detection method for carcinoembryonic antigen (CEA) time-resolved fluorescence lateral flow immunoassay (TRFLFIA), we analyze the spectral properties of europium antibody markers, calculate the label ratio, and verify its biological activity and specificity in conjunction with lateral flow immunochromatographic counting. Goat anti-rabbit IgG monoclonal antibody and CEA mouse anti-human IgG monoclonal antibody I are coated on the NC membrane. Europium-labeled rabbit IgG polyclonal antibody and europium-labeled CEA mouse anti-human IgG monoclonal antibody II are used as labels. The double-antibody sandwich method detects CEA in human saliva. The best emission wavelength of the europium antibody conjugate was 617 nm, and the emission intensity was linearly related to the amount of europium attached to the antibody (R2=0.9999), and the luminescence intensity increased with increase in the number of ligands. CEA mouse anti-human IgG monoclonal antibody has the best europium number of 10.8, and the purification recovery rate is 92.7%; Rabbit IgG polyclonal antibody is labeled with europium, and the purification recovery rate is 88.5%. The detection limit of this method is 1.39 pg/mL. The intra-assay coefficient of variation (CV) is less than 10%, and the inter-assay CV is less than 15%. This method can be used to observe the fluorescence intensity under 365 nm ultraviolet light for qualitative judgment, and it can also use a fluorescence analyzer to quantify the level of CEA in the patient's saliva. The low detection line of this method confirms that CEA-TRFLFIA is a highly sensitive detection method. Because it can complete the test within 10 minutes, it proves the practicality and potential value of this method in the clinical diagnosis of saliva tumor markers and home self-monitoring.