A sensor for detection of carcinoembryonic antigen based on the polyaniline-Au nanoparticles and gap-based interdigitated electrode

A novel immunoassay was designed for ultrasensitive electrochemical detection of carcinoembryonic antigen (CEA) using the polyaniline-Au nanoparticles (PANi-Au NPs) as labels and a gap-based interdigitated electrode (IDEs) as sensor platform. In this strategy, the synthesized adamantine-modified primary antibodies (ADA-Ab(1)) were immobilized on the IDEs functionalized with carboxymethyl-beta-cyclodextrin (cm-beta-CD). After the immuno reaction between Ab(1) and CEA, the polyaniline-Au nanoparticles-labeled antibody (PANi-Au NPs-Ab(2)) as a signal tag was captured onto the immunosensor and connected the microgap of IDEs, which led to the resistance value decrease of IDEs greatly. In addition, the bottom of the immuno platform decorated with CD, Ab(1) and CEA was fully insulated and the electrochemical response only depended on the number of PANi-Au NPs-Ab(2) which was exactly proportional to CEA. The fabricated immunosensor detected CEA with a wide linear range from 0.1 ng/mL to 1000 ng/mL and low detection limit (0.007 ng/mL), and provides an enormous application potential for clinical analysis. (C) 2016 Elsevier B.V. All rights reserved.