Fabrication of a label-free electrochemical immunosensor using a redox active ferrocenyl dendrimer

Abstract

We report an IgG (=immunoglobulin) electrochemical immunosensor using a newly synthesized redox-active ferrocenyl dendrimer of generation 2 (G₂Fc) as a voltammetric transducer. The ferrocenyl dendrimer N(CH₂CH₂C(O)NHCH₂CH₂NHC(O)Fe(η⁵-C₅H₄)(η⁵-C₅H₅))(CH₂CH₂N(CH₂CH₂C(O)NHCH₂CH₂NHC(O)Fe(η⁵-C₅H₄)(η⁵-C₅H₅))₂)₂ (G₂Fc) was used as a functional moiety to immobilize the antibody on the surface of the electrode. A sandwich immunosensor of the type IgG/Bovine serum albumin (BSA)/anti-IgG/G₂Fc/glassy carbon electrode (GCE) was fabricated. The electrochemical properties of G₂Fc were thoroughly studied in aqueous and non-aqueous electrolytes with varying scan rates. The incubation time was optimized for better analytical performance of the immunosensor. It is found that the developed amperometric immunosensor is sensitive to a concentration of IgG as low as 2 ng mL⁻¹.