Label-free electrochemical biosensor based on Ng-PCL polymer signal amplification for the detection of carcinoembryonic antigen

Abstract

Carcinoembryonic antigen (CEA) is the related antigen first extracted from embryonic tissue and is an acidic glycoprotein with human embryonic antigenic properties. It is an important biomarker for the detection of many malignancies. In this paper, we have developed a signal amplified sandwich-type electrochemical impedance biosensor based on naringin initiated poly(ε-caprolactone) (Ng-PCL) polymer for highly sensitive and rapid determination of CEA. The polymer Ng-PCL is a macromolecular polymer that can increase the sensitivity of biosensor. First, SH-functionalized CEA-aptamer 1 (Apt1) was attached to the electrode surface as a recognition probe by Au-S bonds in order to form a self-assembly monolayer (SAM). Then, the one end of CEA antigen could recognize the Apt1 modified on the electrode surface, the other end could recognize the COOH-functionalized CEA-aptamer 2 (Apt2) forming a sandwich structure. Finally, polymer Ng-PCL as a signal amplification unit, which was connected to Apt2 by ester bonds. As a result, the electron transfer in the electrode interface was hindered effectively and a label-free electrochemical impedance sensor was constructed successfully. The high sensitivity and selectivity of biosensor relied on the SAM, polymer Ng-PCL, and specific recognition of CEA. Under the optimum experimental conditions, we proposed electrochemical impedance biosensor had wide detection range between 5 pg/mL and 200 ng/mL, and the sensitivity can reach 0.675 pg/mL. Moreover, the electrochemical impedance biosensor performed high specificity, good stability and satisfactory reproducibility as well. Thus, this strategy will provide new path for the detection of other biomarkers in early clinical diagnosis.