Individual Molecules of Dye‐Labeled DNA Act as a Reversible Two‐Color Switch upon Application of an Electric Field

Reversible switching of the fluorescence of an individual dye-labeled DNA molecule is possible by utilizing an electric field applied in the tip of a nanopipette (see picture; FRET=fluorescence resonance energy transfer). The electric field appears to alter the conformation of the acceptor dye only, resulting in a significant change in its quantum yield.