  This communication reports the effect of DNA conformation on fluorescence
resonance energy transfer (FRET) efficiency between two laser dyes in layer by
layer (LbL) self assembled film. The dyes Acraflavine and Rhodamine B were
attached onto the negative phosphate backbones of DNA in LbL film through
electrostatic attraction. Then FRET between these dyes was investigated.
Increase in pH or temperature causes the denaturation of DNA followed by coil
formation of single stranded DNA. As a result the FRET efficiency also changed
along with it. These observations demonstrated that by observing the change in
FRET efficiency between two laser dyes in presence of DNA it is possible to
detect the altered DNA conformation in the changed environment.
