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

Abstract A novel sandwich-type electrochemical immunosensor was fabricated for the ultrasensitive detection of avian leukosis virus subgroup J (ALV-J). The immunosensor used a β-cyclodextrin-nanogold-ferrocene (β-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 β-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 102.0-104.0 TCID 50 /mL, with a low detection limit of 101.93 TCID 50 /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. Graphical abstract The study reports the successful fabrication of a novel electrochemical immunosensor for the detection of ALV-J, which used a β-CD-AuNP-Fc host-guest complex as the label and a GR-PTCA nanocomposite as the sensor platform. Immobilization of β-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. Image 1 Highlights • A novel signal amplifying strategy was proposed for electrochemical immunosensing ALV-J. • Immobilization of β-CD directly onto Ab 2 simplified the sensor fabrication process. • The strong binding of β-CD and Fc-Au NPs greatly enhanced the detection signal. • The immunosensor displayed high specificity and sensitivity for ALV-J detection. [ABSTRACT FROM AUTHOR]