New label-free DNA recognition based on doping nucleic-acid probes within conducting polymer films

A new biosensing strategy for in situ electrochemical detection of DNA hybridization is described. The label-free approach relies on the doping of nucleic acid probes within electropolymerized polypyrrole (PPy) films and monitoring the current changes provoked by the hybridization event. The study demonstrates that oligonucleotide probes can serve as the sole counter anion during the growth of conducting PPy films, and maintain their hybridization activity within the host polymer network. Distinct hybridization peak signals, with opposite direction in the presence of complementary and non-complementary DNA sequences, are observed in real time. Such unique response is attributed to concomitant conductivity changes, and offers great promise for DNA diagnostics. (C)1999 Elsevier Science B.V. All rights reserved.