Direct immobilization of antibodies on a new polymer film for fabricating an electrochemical impedance immunosensor

A new polymer bearing aldehyde groups was designed and synthesized by grafting 4-pyridinecarboxaldehyde onto poly(epichlorohydrin). Antibodies can be directly immobilized on the surface of the polymer film through the covalent bonding of aldehyde groups of the film with amino groups of antibodies. In this study, human immunoglobulin G (IgG) was used as a model analyte for the fabrication of an electrochemical impedance immunosensor. Using the proposed immunosensor, IgG in the range from 0.1 to 80 ng ml−1 was detected with a detection limit of 0.07 ng ml−1 (signal/noise [S/N] = 3). In addition, the electrochemical impedance immunosensor displays good stability and reproducibility.