An amperometric immunosensor for glycosylated hemoglobin (HbA1c) is reported. A glassy carbon electrode is modified with gold nanoparticles (AuNPs) bearing a ferrocene derivative and a glycosylated pentapeptide (GPP) as an epitope to which anti-HbA1c IgG can selectively bind. The rest of the electrode is passivated with an oligo(ethylene oxide) species to give the electrode resistant to nonspecific adsorption of proteins. Complexation of anti-HbA1c IgG with the surface bound epitope resulted in attenuation of the ferrocene electrochemistry. The immunosensor can detect HbA1c in the range of 4.6%-15.1% of total hemoglobin in human blood by a competitive inhibition assay.
- amperometric immunosensor
- aryl diazonium salts
- functionalized gold nanoparticles