Capillary-Based Three-Dimensional Immunosensor Assembly for High-Performance Detection of Carcinoembryonic Antigen Using Laser-Induced Fluorescence Spectrometry

A novel capillary-based three-dimensional (3D) fluoroimmunosensor for carcinoembryonic antigen detection was explored for the first time. The immunosensor was designed in symmetrical cylinder structure and fabricated with capillary tubes encapsulated in a quartz tube. The 3D design of the sensor increased the area of sensing surface, flexibility in light path design and efficiency of fluorescence collection by aluminum foil, resulting in analytical performance improvement. The CEA immunosensor was constructed in double antibody sandwich format. Fluorescence signals from DyLight 550-labeled antibody were measured using a laser-induced fluorescence spectrometry. There is an obvious improvement in the linear detection range of 0.7-80 ng/mL. This novel 3D immunosensor dramatically improved the detection limit (1.1 pmol/L CEA) and sensitivity. Assay validation studies indicated that the correlation coefficient reached 0.9935, with recoveries of 92.82-118.81%. Furthermore, the immunosensor was successfully applied to CEA determination in actual saliva specimens with high sensitivity and acceptable precision. Regarding accuracy, the results obtained by 3D immunosensor were not significantly different (t test) from those obtained by validated electrochemiluminescence immunoassay. This new 3D CEA immunosensor was demonstrated to be a high-performance tool for CEA diagnostics.