Gold electrode functionalized by electropolymerization of a cyano N-substituted pyrrole: application to an impedimetric immunosensor

An impedimetric immunosensor based on functionalized electropolymerized lag ers has been developed. The proposed experimental procedure involves. prima rily, the electrogeneration of an N-substituted polypyrrole, carrying termi nal cyano groups, on gold electrodes, The latter was characterized by cycli c voltammetric measurements performed in the range 0-0.8 V. Then, immobiliz ation of the antibodies (anti-rabbit IgG) was achieved through electrostati c interactions between the terminal cyano groups of the polymer and the hyd roxyl groups of the antibodies. The efficiency of this immobilization metho d was revealed by both gravimetric and permeation measurements, Impedance m easurements have been used to characterize the electrical characteristics o f the functionalized electrodes in order to optimize the working conditions of the immunosensor. It appears that, at a bias potential of -1.425 V, the Warburg impedance is negligible and the variation of the impedance caused by specific interaction between immune species can be exploited for sensing purposes, especially at low frequency. Thus, the sensor based on this immo bilization method exhibits a good selectivity as well as a large linear dyn amic range, fi um 600 ne ml(-1) to 900 ng ml(-1). (C) 2001 Elsevier Science B.V. All rights reserved.