Two independent label-free detection methods in one electrochemical DNA sensor.

Two direct reagent-free detection methods were tested with Au/polypyrrole/oligonucleotide modified electrodes. Detection by monitoring guanine oxidation was realized amperometrically using an experimental setup which does not require any expensive electrochemical equipment and is therefore suitable for in situ detection. Target detection was also realized by monitoring the decrease in the amplitude of polypyrrole oxidation and reduction peaks in cyclic voltammetry experiments after incubation or injection of target into the electrochemical cell. Detection of 53 pM target within a 2000x excess of non-complementary sequences was possible. The possibility of a dual detection scheme in the same biosensor, with both detection schemes being totally independent from one another is very promising for genosensor design since it would result in a significant decrease in the number of false positive and false negative samples.