Electrochemical sensor for detection of unmodified nucleic acids.

We have developed a nucleic acid (NA) sensor based on mediated electrochemical oxidation of guanine residues. In this method, oligonucleotide probes are bound to a tin-doped indium oxide (ITO) electrode through a self-assembled phosphonate monolayer. The end carboxyl moiety of the monolayer is activated with carbodiimide and reacted with the amine group of a C6 alkyl linker which has been added to the 5'-end of the oligonucleotide probe.