Electrical Detection of Nucleic Acids using Target-Guided Formation of Conducting Polymer Nanowires in Nanogaps

A nanogapped microelectrode-based biosensor array is fabricated for ultrasensitive electrical detection of nucleic acids. After immobilizing peptide nucleic acid (PNA) capture probes in nanogaps of a pair of interdigitated microelectrodes and performing hybridization with their complementary target nucleic acids, the deposition of conducting polymer, polyaniline (PAn) nanowires, is carried out by an enzymatically catalyzed method, where the electrostatic interaction between anionic phosphate groups in nucleic acids and cationic aniline molecules is exploited to guide the formation of the PAn nanowires onto the hybridized target nucleic acids. The conductivity of the deposited PAn nanowires directly correlates to the amount of the hybridized nucleic acids. Under optimized conditions, the target nucleic acid can be quantified in a range of 10 fM-20 pM with a detection limit of 5.0 fM.