A stable and sensitive voltammetric immunosensor based on a new non-enzymatic label

A stable and sensitive electrochemical carcinoembryonic antigen immunosensor based on a new nonenzymatic label (3, 3', 5, 5'-tetramethylbenzidine (TMB)) was fabricated using gold nanoparticles-deposited polydopamine film (PD/AuNPs) as an anti-CEA antibody immobilizing platform. TMB was conjugated with CEA and utilized as an electrochemical label. The PD/AuNPs platform provides enhanced conductivity, thus the redox reaction of TMB label was observed at the immunosensor probe. The immunosensor probe was characterized using scanning electron microscopy and electrochemical impedance spectroscopy. The CEA detection was based on the competitive binding of free- and TMB-conjugated-CEA to the anti-CEA antibody. Using differential pulse voltammetry, CEA can be selectively detected as low as 10 +/- 0.6 pg/mL. The present immunosensor method was applied to CEA-spiked human serum samples and the recovery results were satisfactory. (C) 2013 Elsevier B.V. All rights reserved.