Electrochemical amperometric immunoassay for carcinoembryonic antigen based on bi-layer nano-Au and nickel hexacyanoferrates nanoparticles modified glassy carbon electrode

This study demonstrates a new approach towards development of novel immunosensor based on gold nanoparticles (nano-Au) and nickel hexacyanoferrates nanoparticles (NiHCFNPs) for determination of carcinoembryonic antigen (CEA) in clinical immunoassay. The fabrication steps of the immunosensor as follows: firstly, nano-Au was immobilized on the surface of bare glassy carbon electrode (CCE) by using a simple method - electrochemical reduction of HAuCl4 solution: secondly, NiHCFNPs as an electroactive substance was immobilized on the layer of gold nanoparticles. Microstructure and surface morphology of NiHCFNPs have been characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM); thirdly, nano-Au was again immobilized on the surface of NiHCFNPs, which can offer a favorable microenvironment and biocompatibility to immobilize anti-CEA. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were applied to characterize the electrochemical properties of modified process. Effect of deposition time of nano-Au, pH of working buffer, incubation temperature and time were studied in detail for optimization of analytical performance. Under optimal conditions, the peak current of CV of the immunosensor decreased linearly with increasing CEA concentration in two ranges from 0.5 to 10.0 ng mL(-1) and from 10.0 to 160.0 ng mL(-1), with a detection limit 0.1 ng mL(-1) at three times background noise. The proposed immunosensor show good repeatability and reproducibility, acceptable accuracy, high sensitivity and would be valuable for diagnosis and monitoring of carcinoma. (C) 2008 Elsevier B.V. All rights reserved.