Quantitative Immunochromatographic Strip Biosensor for the Detection of Carcinoembryonic Antigen Tumor Biomarker in Human Plasma

Combining the unique optical properties of gold nanoparticle (Au-NP) and the antibody-antigen specific molecular recognition, a quantitative immunochromatographic strip biosensor (QISB) in connection with a portable strip reader was developed for the detection of carcinoembryonic antigen (CEA) tumor biomarker in human plasma. The test is based on the principle of sandwich-type immunreaction on the lateral flow test strip. The polyclonal antibody (Ab) and Au-NP labeled monoclonal Ab are employed to identify CEA specifically. The quantitative detection of CEA was realized by recording the optical intensities of the produced red bands in the strip biosensor with the portable strip reader. The biosensor fabrication and assay parameters (e.g. membrane sources, the concentration of polyclonal Ab in the test zone, the amount of AuNP-anti-CEA conjugates and the components of running buffer) that govern the sensitivity and reproducibility of the biosensor were optimized. Under optimal conditions, the response of the QISB is linear in the range of 10 200 ng mL -1 with a detection limit of 5 ng mL -1 (S/N = 3) in association with a 10-min assay time. The biosensor has also been successfully applied for the detection of CEA in human serum sample. The QISB thus provides a rapid, sensitive, low cost clinical diagnosis tool for the detection of protein biomarkers in biological samples.