Impedimetric immunosensor based on conductive and adhesive gold/polypyrrole-dopamine nanocomposite for the detection of carcino-embryonic antigen

A novel impedimetric immunosensor was fabricated for the determination of carcino-embryonic antigen (CEA) using conductive and adhesive gold/polypyrrole-polydopamine nanocomposite as an immobilization matrix. A polypyrrole-polydopamine complex (PPy-PDA) was first prepared by the polymerization of pyrrole and dopamine, which was then blended with chloroauric acid solution (HAuCl 4 ). The in situ reduction of AuCl 4 − ions to gold nanoparticles (Au NPs) by polydopamine leads to the successful preparation of gold/polypyrrole-polydopamine nanocomposites (Au/PPy-PDA). The obtained Au/PPy-PDA nanocomposite not only provides a highly biocompatible and stable matrix for loading antibody, but also accelerate the electron transfer process owing to the conductive PPy as well as encapsulated Au NPs, which is quite suitable to be applied as high-efficiency immunoassay platform. CEA antibody (CEA-Ab) was efficiently loaded on Au/PPy-PDA film, and a label-free impedimetric immunosensor was successfully constructed. Under optimal conditions, a wide linear range (0.001–500 ng mL −1 ) and low detection limit (0.2 pg mL −1 ) was demonstrated for the detection of CEA. Furthermore, the proposed CEA immunosensor exhibited high specificity, excellent reproducibility, and stability, providing an experimental evidence for early diagnosis of cancer. Accurate detection of CEA in human serum samples was also exhibited.