Nanosilver-doped DNA polyion complex membrane for electrochemical immunoassay of carcinoembryonic antigen using nanogold-labeled secondary antibodies |
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Authors: | Wei Wu Ping Yi Ping He Kelong Liao Haidong Wang |
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Institution: | a Department of Cardiothoracic Surgery, Southwest Hospital, Third Military Medical University, Chongqing 400038, PR China b Department of Obstetrics and Gynecology, Daping Hospital, Third Military Medical University, Chongqing 400042, PR China c Department of Cardiology, Southwest Hospital, Third Military Medical University, Chongqing 400038 PR China |
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Abstract: | A simple and sensitive electrochemical immunoassay protocol was developed for the detection of carcinoembryonic antigen (CEA) using nanosilver-doped DNA polyion complex membrane (PIC) as sensing interface. To construct such an immunosensor, double-stranded DNA was initially assembled onto the surface of thionine/Nafion-modified screen-printed carbon electrode to adsorb silver ions with positive charges, then silver ions were reduced to nanosilver particles with the aid of NaBH4, and then anti-CEA antibodies were immobilized on the nanosilver surface. Gold nanoparticles conjugated with horseradish peroxidase-labeled anti-CEA were employed as signal antibodies for the detection of CEA with a sandwich-type assay format. Under optimal conditions, the immunosensor exhibited a dynamic range of 0.03-32 ng mL−1 with a low detection limit of 10 pg mL−1 CEA. Intra- and inter-assay imprecision (CVs) were <9.5% and 6.5%, respectively. The response could remain 90.1% of the original current at 30th day. 50 real samples were evaluated using the immunosensor and the enzyme-linked immunosorbent assay, respectively, and received in accordance with those two methods. |
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Keywords: | Carcinoembryonic antigen Electrochemical immunosensor Polyion complex membrane Silver nanoparticles |
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