A fluorescence probe of 3-methoxybenzanthrone (MBA) exhibits significant so
lvatochromic characteristics correlated with the polarity of solvents. The
interaction of the solvatochromic fluorescence probe with calf thymus DNA (
ct-DNA) has been investigated. In the presence of ct-DNA the fluorescence o
f MBA is strongly quenched with a blue-shift of emission peak and a hypochr
omism in absorption spectra. The absorption spectral fluorescence quenching
and fluorescence polarization experiments show that the MBA molecule as an
intercalator is inserted into the base-stacking domain of the ct-DNA doubl
e helix, and the interaction of the nucleobases with the MBA molecule cause
s quenching of fluorescence and hypochromism in the absorption spectra, The
intrinsic binding constant and the binding site number were determined to
be 1.70 x 10(5) mol l(-1) in base pairs and six, respectively. The I-0/I ve
rsus [ct-DNA] plot shows linear relationship in the range covering 4.3 x 10
(-7) - 1.02 x 10(-4) mol l(-1) in base pairs which can be used for ct-DNA d
etermination. The limit of detection was found to be 4.3 x 10(-7) mol l(-1)
in base pairs (0.5 mu g ml(-1)). (C) 1999 Elsevier Science B.V. All rights
reserved.