Oligonucleotide–functionalised poly(3,4-ethylenedioxythiophene)-coated microelectrodes which show selective electrochemical response to hybridisation

A carboxylic acid–functionalised 3,4-ethylenedioxythiophene (EDOT) derivative has been synthesised. Its co-polymerisation with EDOT on a Pt disk microelectrode gave a redox-active poly-3,4-ethylenedioxythiophene (PEDOT) with pendant –COOH groups. These were coupled in situ to an aminoalkyl-terminated oligonucleotide. The p-doping peak in the cyclic voltammogram of the PEDOT changed slightly upon grafting, but underwent a much more marked change upon hybridisation with the complementary oligonucleotide.