In-situ Synthesis and Stabilization of Silver Nanoparticles in a Bilayer Polydopamine Architecture for Label-Free Electrochemical Immunosensing of Carcinoembryonic Antigen

Abstract

Abstrart: A simple, label-free electrochemical immunosensor for the detection of carcinoembryonic antigen (CEA) was developed using a nanocomposite. The sensing interface was constructed via a bilayer polydopamine (PDA) strategy: a PDA layer was first self-assembled on the electrode surface, utilizing its reducing capability for the in-situ synthesis of silver nanoparticles (AgNPs). A secondary PDA layer was then applied to stabilize the AgNPs and provide active groups for the immobilization of the primary antibody. The fabrication process of the immunosensor was monitored by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The differential pulse voltammetry (DPV) peak current decreased linearly with increasing CEA concentration (0.05-20 ng/mL). The calibration curve was defined as I (μA) = -0.5681 c [CEA] (ng/mL) + 11.9079 with a correlation coefficient (R) of 0.9936. This study provides a feasible technical route for CEA detection within the clinically relevant range, featuring simple fabrication and excellent reproducibility, showing great potential for point-of-care (POC) testing devices.