A novel electrochemical immunosensor using β-cyclodextrins functionalized silver supported adamantine-modified glucose oxidase as labels for ultrasensitive detection of alpha-fetoprotein

In this work, a novel sandwich-type electrochemical immunosensor based on host-guest interaction was fabricated for the detection of alpha-fetoprotein (AFP). Due to the large specific surface area of multi-walled carbon nanotubes and the unique supramolecular recognition ability of beta-cyclodextrins, ferrocenecarboxylic acid (Fc) was incorporated into this sensor platform by host-guest interaction to generate an electrochemical signal. And beta-cyclodextrins functionalized silver supported adamantine-modified glucose oxidase (GOD-CD-Ag), was used as a label to improve the analytical performance of the immunosensor by the dual amplification strategy. The obtained GOD-CD-Ag conjugates could convert glucose into gluconic acid with the formation of hydrogen peroxide (H2O2). And then silver nanoparticles could in situ catalyze the reduction of the generated H2O2, dramatically improving the oxidation reaction of Fc. The developed immunosensor shows a wide linear calibration range from 0.001 to 5.0 ng/mL with a low detection limit (0.2 pg/mL) for the detection of AFP. The method, with ideal reproducibility and selectivity, has a wide application prospect in clinical research. (C) 2015 Elsevier B.V. All rights reserved.