Direct electrochemical sensor for fast reagent-free DNA detection.

A novel reagentless direct electrochemical DNA sensor has been developed using ultrathin films of the conducting polymer polypyrrole doped with an oligonucleotide probe. Our goal was to develop a prototype electrochemical DNA sensor for detection of a biowarfare pathogen, variola major virus. The sensor has been optimized for higher specificity and sensitivity. It was possible to detect 1.6 fmol of complementary oligonucleotide target in 0.1 ml in seconds by using chronoamperometry. The sensitivity of the developed sensor is comparable to indirect electrochemical DNA sensors, which use electrochemical labels and reagent-intensive amplification. The developed sensing electrode is reusable, highly stable and suitable for storage in solution or in dry state.