Three-dimensional gold nanoparticles/prussian blue-poly(3,4-ethylenedioxythiophene) nanocomposite as novel redox matrix for label-free electrochemical immunoassay of carcinoembryonic antigen

We present a novel label-free electrochemical immunosensor for detecting carcinoembryonic antigen (CEA) based on three-dimensional (3D) gold nanoparticles/prussian blue-poly(3,4-ethylenedioxythiophene) (AuNPs/PB-PEDOT) nanocomposite, which was firstly synthesized by a simple redox reaction between the PB precursors and EDOT in an aqueous solution, followed by the electrochemical reduction of HAuCl4. The 3D nanocomposite not only possessed large surface area and favorable microenvironment, but also exhibited remarkable conductivity, stability and excellent biocompatibility. In addition, PB showed excellent redox properties. Then AuNPs/PB-PEDOT was used as both electron mediators and 3D matrices in the fabrication of immunosensor. FT-IR spectra were employed to confirm the formation of PB, PEDOT and PB-PEDOT. Significantly, the AuNPs/PB-PEDOT exhibited a 3D and hierarchically porous nanostructure, while the PB-PEDOT showed core-shell structure. The AuNPs/PB-PEDOT modified immunosensor showed good linearity with the concentration of CEA ranging from 0.05 to 40 ng mL−1, and the detection limit was 0.01 ng mL−1. Moreover, the prepared electrode displayed good selectivity, high stability and good repeatability, and showed great potential for application in real sample analysis.