Ultrasensitive electrochemical immunosensor for avian leukosis virus detection based on a β-cyclodextrin-nanogold-ferrocene host-guest label for signal amplification

A novel sandwich-type electrochemical immunosensor was fabricated for the ultrasensitive detection of avian leukosis virus subgroup J (ALV-J). The immunosensor used a (beta-cyclodextrin-nanogold-ferrocene (beta-CD-AuNP-Fc) host-guest complex as the label and a perylene-3,4,9,10-tetracarboxylic acid functional graphene nanocomposite (GR-PTCA) as the sensor platform. The abundant polycarboxylic sites of GR-PTCA facilitated the binding of primary antibodies (Ab(1)), whilst the excellent electrical conductivity of GR-PTCA promoted electron transfer. Immobilization of beta-CD directly onto secondary antibodies (Ab(2)) via covalent bonding allowed strong binding of ferrocene-decorated gold nanoparticles (Fc-Au NP), thereby amplifying the immunosensor signal. Under optimized testing conditions, the reduction current of ferrocene exhibited a linearly dependence on the ALV-J titer in the concentration range of 10(2.0) -10(4.0) TCID50/mL, with a low detection limit of 10(1.93) TCID50/mL. Furthermore, the immunosensor demonstrated high sensitivity, good reproducibility, reusability and stability, suggesting excellent potential for the quantitative detection of ALV-J in clinical applications. (C) 2019 Elsevier B.V. All rights reserved.