An electrochemical aptasensor for highly sensitive detection of CEA based on exonuclease III and hybrid chain reaction dual signal amplification.

At present, carcinoembryonic antigen (CEA) is considered a broad-spectrum cancer biomarker, and its accurate analysis in clinical samples can assist early cancer diagnosis and treatment. Herein, a novel electrochemical aptasensor has been proposed for CEA detection based on exonuclease III and hybrid chain reaction. The target CEA specifically binds to the aptamer region in hairpin probe 1 (defined as H1) by strong attraction, which leads the rest of the H1 triggering catalytic hairpin assembly to form a high quantity of H1 and hairpin probe 2 (defined as H2) double chain complex (denoted as H1@H2). Subsequently, the exonuclease III digests the complex of H1@H2 and liberates H1 to induce the first signal amplification. Simultaneously, a large number of generated trigger chains initiate a hybrid chain reaction and produce a second signal amplification. This proposed sensor exhibited excellent analytical performance for the detection of CEA, with wide linear range from 10 pg.mL to 100 ng.mL and low limit of detection of 0.84 pg.mL. Additionally, the biosensing strategy was successfully verified for direct measurement of CEA in human serum. Therefore, this elaborated sensor provides a new simple method for detecting CEA and exhibits great promise in the early screening of cancer.