Study of electronic excitation energy transfer between cyanine dye molecules noncovalently bound to DNA

Electronic excitation energy transfer between molecules of carbocyanine dyes noncovalently bound to DNA was studied. 3,3′,9-Triethyl-5,5′-dimethyloxacarbocyanine iodide and 3,3′-dimethyl-9-ethyloxacarbocyanine iodide were used as energy donors, and 3,3′-diethylthiacarbocyanine iodide served as an acceptor dye. The fluorescence decay kinetics of the donors and its quenching by the acceptor in the presence of DNA were measured. The microphase model was used for interpretation of the experimental data, with allowance for concentrating dye molecules in the vicinity of DNA molecules.