The effect of cetyl-trimethylammonium bromide (CTAB)
on enhancing the fluorescence resonance energy transfer
(FRET) between two dye-conjugated DNA strands was
studied using fluorescence emission spectroscopy and dynamic
light scattering (DLS). For hybridized DNA where
one strand is conjugated with a TAMRA donor and the
other with a TexasRed acceptor, increasing the concentration
of CTAB changes the fluorescence emission properties
and improves the FRET transfer efficiency through
changes in the polarity of the solvent, neutralization of
the DNA backbone and micelle formation. For the DNA
FRET system without CTAB, the DNA hybridization
leads to contact quenching between TAMRA donor and
TexasRed acceptor producing reduced donor emission
and only a small increase in acceptor emission. At 50 μM
CTAB, however, the sheathing and neutralization of the
dye-conjugated dsDNA structure significantly reduces
quenching by DNA bases and dye interactions, producing
a large increase in FRET efficiency, which is almost four
fold higher than without CTAB.