Sensitive detection of carcinoembryonic antigen with magnetic nano-bead and upconversion nanoparticles-based immunoassay

A novel magnetic nanobead-based immunoassay was developed for the quantification of carcinoembryonic antigen (CEA) in human serum in this study. Amine-functionalized Fe3O4 magnetic nanoparticles (MNPs) were conjugated with capture anti-CEA antibodies and amine-functionalized NaY0.78F4:Yb0.20, Ho0.02 upconversion nanoparticles (UCNPs) were synthesized and conjugated with detection anti-CEA antibodies, respectively. Based on a sandwich-type immunoassay format, the detection limit for CEA under optimal conditions was as low as 2.5 pg/mL, and the linear range of CEA detection was from 2.5 × 10−12 to 1 × 10−8 g/mL (I = 406.19 log X + 428.81) with a correlation coefficient equal to 0.9987. The established method was successfully applied to measure CEA in human serum samples and more sensitive than a commercially available chemiluminescence method. The precision expressed as the relative standard deviation of CEA detection was equal to 5.19% (1 ng/mL) or 4.36% (5 pg/mL), indicating that the developed method exhibited good reproducibility. The results demonstrate that the method offers potential advantages of sensitivity and good reproducibility for the determination of CEA, and is applicable to the determination of CEA in serum samples.