Surface-Quenched Hairpins Detect DNA

A biosensor developed at the University of Rochester in New York that uses its gold substrate to quench fluorophore-functionalized DNA hairpins on the surface promises to detect complementary sequences at femtomolar concentrations. The researchers presented their initial results in the April 9 issue of the Journal of the American Chemical Society.

They designed the hairpins so that one end attached to the gold substrate and the other, which was linked to rhodamine dye, dangled near the surface so that its fluorescence was quenched by approximately 95 percent. In the presence of the target molecule, the hairpin straightened, exposing the fluorophore to the excitation light and increasing the response by more than a factor of 20.