Electronic detection of nucleic acids - A versatile platform for moleculardiagnostics

A novel platform for the electronic detection of nucleic acids on microarra ys is Introduced and shown to perform well as a selective detection system for applications in molecular diagnostics. A gold electrode in a printed ci rcuit board is coated with a self-assembled monolayer (SAM) containing DNA capture probes, Unlabeled nucleic acid targets are immobilized on the surfa ce of the SAM through sequence-specific hybridization with the DNA capture probe. A separate signaling probe, containing ferrocene-modified nucleotide s 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 th e gold, while Insulating the electrode from soluble redox species, includin g unbound signaling probes. Here, we demonstrate sequence-specific detectio n of amplicons after simple dilution of the reaction product Into hybridiza tion buffer. In addition, single nucleotide polymorphism discrimination is shown. A genotyping chip for the C282Y single nucleotide polymorphism assoc iated with hereditary hemochromatosis Is used to confirm the genotype of si x 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 t hrough sequence-specific hybridization demonstrates the potential of this s ystem for infectious disease diagnostics. The versatility of the electronic detection platform makes h suitable for multiple applications in diagnosti cs and pharmacogenetics.