A sandwich-type amperometric immunosensor fabricated by Au@Pd NDs/Fe2+-CS/PPy NTs and Au NPs/NH2-GS to detect CEA sensitively via two detection methods

摘要

The quantitative detection of carcinoembryonic antigen (CEA) is significant to assess tumor status and therapeutic efficiency. In this study, a sandwich-type amperometric immunosensor for CEA detection sensitively was fabricated by novel signal amplification system. The signal amplification system was formed by gold nano particles loaded on amino functionalized graphene sheet (Au NPs/NH2-GS) and gold@palladium nanodendrites loaded on ferrous-chitosan functionalized polypyrrole nanotubes (Au@Pd NDs/Fe2+-CS/PPy NTs). Au NPs/NH2-GS as platform enhanced the electron transfer proven by apparent electron transfer rate constant. Au@Pd NDs/Fe2+-CS/PPy NTs nanocomposite as label appeared high catalytic activity to hydrogen peroxide reduction. Thus, the immunosensor showed wide linear concentration range (50 fg/mL to 50 ng/mL) and low detection limit of 17 fg/mL via amperometric i-t curve (i-t). Significantly, the nanocomposite can act as electroactive substance, which provided a good method to detect CEA without additional electroactive substance via square wave voltammetry (SWV). An overlapping linear concentration range (500 fg/mL to 5.0 ng/mL) was obtained compared i-t with SWV.