An electrochemical gene detection assay utilising T7 exonuclease activity on complementary probe-target oligonucleotide sequences

This communication describes the synthesis of an electrochemically active oligonucleotide probe and its application in sensing complementary oligonucleotides sequences using a T7 exonuclease enzyme. Target oligonucleotides are detected by hybridisation with a ferrocene labelled probe oligonucleotide followed by addition of T7 exonuclease. The T7 enzyme is a double strand specific exonuclease that removes the terminal 5' nucleotide of the probe sequence. The 5' nucleotide is attached to a ferrocene label, which is subsequently detected at an electrode using differential pulse voltammetry. Time and temperature resolved measurements were performed and an associated study using dual labelled fluorophore-quencher labelled probes was performed to confirm the validity of the electrochemical assay. (C) 2004 Published by Elsevier B.V.