A monolithic silicon based integrated signal generation and detection system for monitoring DNA hybridisation

Prehybridised duplex DNA, consisting of thiolated oligonucleotide and ruthenium labelled complementary oligonucleotide, was assembled on the gold initiation electrode. The difference between the current measured during flow of buffer and the ECL coreactant TPA was three orders of magnitude, indicating that DNA assembled on the surface comprised sufficient ruthenium to generate a measurable signal. Finally, the displacement of unlabelled partial mismatch oligonucleotide from the sensor surface was monitored on addition of the ruthenium labelled perfectly complementary oligonucleotide in TPA flow and the measured photodiode current response was up to 50 times greater.