A sensitive DNA sensor based on an organic electrochemical transistor using a peptide nucleic acid-modified nanoporous gold gate electrode

An organic electrochemical transistor (OECT) based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate with porous anodic aluminum oxide (AAO) as a gate electrode was proposed for DNA sensing. The AAO substrate, which possesses a pore size of 200 nm, underwent gold nanofilm deposition by the thermal evaporation technique and is referred to as a nanoporous gold electrode in this work. Due to its high sensitivity, target DNA as low as 0.1 nM in concentration was achieved on an OECT device with a nanoporous gold gate electrode using a peptide nucleic acid probe. One-base and two-base mismatched DNA sequences could be discriminated. A sensing mechanism for the OECT device based on the nanoporous gold electrode was proposed. The synergetic effect of capacitance with the surface potential on the nanoporous gold electrode enlarged the increase in gate potential, which resulted in high sensitivity for DNA sensing.