Label-free detection of DNA hybridization based on a novel functionalized conducting polymer

A new functionalized pyrrole monomer, 3-pyrrolylacrylic acid (PAA) was synthesized. It was used to prepare a copolymer with pyrrole, poly(Py-co-PAA), which was investigated by reflective FT-IR, UV–vis spectroscopy and cyclic voltammetry. A label-free DNA sensor was prepared based on a poly(Py-co-PAA) film. Hybridization with complementary and non-complementary DNA targets was studied by electrochemical impedance spectroscopy. Results show a significant increase in the charge-transfer resistance upon addition of complementary target. The impedance spectra were analyzed by using a modified Randles and Ershler equivalent circuit model. The change in charge-transfer resistance that was used as an index of sensor response was found to be linear with logarithmic target concentration in the range of 2 × 10−9 to 2 × 10−7 M. The detection limit was 0.98 nM.