Abstract

Fluorescence resonance energy transfer (FRET)¹ is a standard spectroscopic technique for measuring distances in the 10–75 Å range. We extended the technique's sensitivity by measuring energy transfer between a single donor fluorophore and a single acceptor fluorophore. Near-field scanning optical microscopy (NSOM)² was used to obtain simutaneous dual color imaging and emission spectra from a single pair of donor and acceptor fluorophores linked by a short (10 or 20 bases long) DNA molecule. The DNA was dried on amino-propyl-silanized glass. Near-field fluorescence images³ and emission spectra⁴ were taken on single DNA molecules labeled with donor only, with acceptor only, or with both donor and acceptor.

© 1996 Optical Society of America