A sensitive amperometric immunosensor for carcinoembryonic antigen detection with porous nanogold film and nano-Au/chitosan composite as immobilization matrix

A sensitive amperometric immunosensor for carcinoembryonic antigen (CEA) was prepared. Firstly, a porous nano-structure gold (NG) film was formed on glassy carbon electrode (GCE) by electrochemical reduction of HAuCl₄ solution, then nano-Au/Chit composite was immobilized onto the electrode because of its excellent membrane-forming ability, and finally the anti-CEA was adsorbed onto the surface of the bilayer gold nanoparticles to construct an anti-CEA/nano-Au/Chit/NG/GCE immunosensor. The characteristics of the modified electrode at different stages of modification were studied by cyclic voltammetry (CV). The gold colloid, chitosan and nano-Au/Chit were characterized by transmission electron microscopy and UV–vis spectroscopy. In addition, the performances of the immunosensor were studied in detail. The resulting immunosensor offers a high-sensitivity (1310 nA/ng/ml) for the detection of CEA and has good correlation for detection of CEA in the range of 0.2 to 120.0 ng/ml with a detection limit of 0.06 ng/ml estimated at a signal-to-noise ratio of 3. The proposed method can detect the CEA through one-step immunoassay and would be valuable for clinical immunoassay.