Electronic detection of nucleic acids - A versatile platform for molecular diagnostics

A novel platform for the electronic detection of nucleic acids on microarrays is Introduced and shown to perform well as a selective detection system for applications in molecular diagnostics. A gold electrode in a printed circuit board is coated with a self-assembled monolayer (SAM) containing DNA capture probes, Unlabeled nucleic acid targets are immobilized on the surface of the SAM through sequence-specific hybridization with the DNA capture probe. A separate signaling probe, containing ferrocene-modified nucleotides and complementary to the target in the region adjoining the capture probe binding site, is held in close proximity to the SAM in a sandwich complex. The SAM allows electron transfer between the immobilized ferrocenes and the gold, while Insulating the electrode from soluble redox species, including unbound signaling probes. Here, we demonstrate sequence-specific detection of amplicons after simple dilution of the reaction product Into hybridization buffer. In addition, single nucleotide polymorphism discrimination is shown. A genotyping chip for the C282Y single nucleotide polymorphism associated with hereditary hemochromatosis Is used to confirm the genotype of six patients' DNA In addition, a gene expression-monitoring chip is described that surveys five genes that are differentially regulated In the cellular apoptosis response. Finally, custom modification of individual electrodes through sequence-specific hybridization demonstrates the potential of this system for infectious disease diagnostics. The versatility of the electronic detection platform makes h suitable for multiple applications in diagnostics and pharmacogenetics.