An Electrochemical Aptasensor for Highly Sensitive Detection of CEA Based on Exo III and HCR Dual Signal Amplification

Abstract

At present, Carcinoembryonic antigen（CEA）is considered as a broad-spectrum tumor biomarker, the accurate analysis of CEA in clinical samples can assist early diagnosis and treatment of cancer. Herein，a novel electrochemical aptasensor has been proposed for CEA detection based on Exo III and HCR dual signal amplification. The target CEA specifically is binded to aptamer region in H1 through a strong attraction, thereby triggering the CHA cycle to form plenty of H1@H2 duplex. Subsequently, the Exonuclease III digested complex and liberated the target to induce the first signal amplification, and generated a large number of trigger chains simultaneously. Then, these triggers can hybridize with the capture probes and MB-labeled S1 and S2, producing amplified electrochemical signal significantly on the electrode surface. The integration of HCR and EXO-III assisted target circulation endowed the sensor excellent analytical performance for the detection of CEA, with a wide linear range from 10 pg.ml -1 to 100 ng.ml -1 , high sensitivity of limit of detection (LOD) of 1.2 pg.ml -1 . What’s more, the biosensing strategy was successfully verified for directly identifying CEA in human serum samples and exhibited admirable stability and precision. Therefore, this elaborated sensor opens a new simple way for detecting CEA and exhibits a great promise in the early screening of tumor.