Label-free DNA detection based on a novel nanostructured conducting poly(indole-6-carboxylic acid) films

A simple and label-free electrochemical sensor for detection of DNA hybridization event was obtained based on a novel nanostructured conducting polymer, poly(indole-6-carboxylic acid). This precursor polymer with high electroactivity can be easily prepared by direct electrochemical polymerization of indole-6-carboxylic acid in acetonitrile containing tetrabutylammonium tetrafluoroborate. An 18-mer amino-substituted oligonucleotide (ODN) probe was covalently grafted onto the polymer in a one-step procedure. The performance of this label-free electrochemical DNA sensor was investigated by using cyclic voltammetry (CV) as a readout method. This simple sensor can discriminate one-base mismatched and non-complementary ODN sequences and can be regenerated after a dehybridization step. The dynamic determination range for complementary target ODN was from 3.5 × 10−10 mol L−1 to 2.0 × 10−8 mol L−1 and the corresponding detection limit was 5.79 pmol L−1.