A label-free and lectin-based sandwich aptasensor for detection of carcinoembryonic antigen

Carcinoembryonic antigen (CEA), a glycoprotein, is a wide-spectrum tumor marker for cancer diagnosis. Developing simple, stable, and low-cost methods for CEA detection is of great importance. In this work, a novel, label-free, and antibody-free electrochemical sandwich CEA biosensor was developed based on concanavalin A (ConA) and a DNA aptamer against CEA. Horse radish peroxidase (HRP) was labeled on the sandwich structure for signal production and amplification. Both the CEA and the HRP bind to ConA through sugar-lectin interactions. Under optimum conditions, the detection linear range was from 5 to 40 ngmL(-1) CEA, with a detection limit of 3.4 ngmL(-1), lower than the threshold level in human serum for cancer patients (similar to 10 ngmL(-1)). The biosensor is reproducible, accurate, specific, and stable, with RSD value of 3% for inter-biosensors, and relative error of <13% compared with those obtained by a commercial diagnostic kit. No obvious responses were observed toward interfering proteins. Storage did not cause obvious signal diminishment for the biosensor. The simple and low-cost aptasensor is promisingly applicable for CEA detection in cancer diagnosis, and could be able to serve as a general platform for detection of other interested glycoproteins. (C) 2017 Elsevier B.V. All rights reserved.