Dramatic increases in resonance energy transfer have been observed between fluorophores bound to DNA above metallic silver islands: Opportunities for long-range immunoassays and new DNA arrays

The dramatic increase in resonance energy transfer (RET) between fluorophores bound to DNA above metallic silver islands is discussed. In nearly all cases of resonance energy transfer (RET), its usefulness as a spectroscopic ruler is determined by the magnitude of the Förster distance, R o. For the most favorable case of high spectral overlap and high quantum yield, the maximum value of Ro is near 55 Å for organic fluorophores and up to 90 Å for lanthanide donors. It is found that these short free-space Förster distances may be substantially increased by placing the donor and acceptors pairs above silver island films.