Angew. Chemie Int. Edn doi:10.1002/anie.200902577 (2009)

MicroRNA molecules — key regulators of many cellular and disease processes — can be quickly measured even at low levels using a chip-based detector developed by Shana Kelley of the University of Toronto, Canada, and her colleagues.

The silicon microchip has tiny palladium electrodes coated with synthetic peptide nucleic acids, which bind to specific microRNA (miRNA) molecules. To generate a signal, the researchers incorporated a ruthenium-based reporting system into the chip. When a certain level of miRNA is bound at the electrodes, ruthenium ions are electrochemically reduced, giving off an electrical signal.

The chip was able to detect 100 molecules per microlitre of a specific miRNA in about 30 minutes. It also indicated much higher levels of cancer-associated miRNAs in human head and neck cancer cell extracts than in normal cell extracts.