Tokar V. Spectral manifestations of the interaction of nucleic acids with low-molecular pi-electron containing compounds

Thesis is devoted to the experimental study by spectral methods of the electronic processes which take place in the systems DNA macromolecule – styrylcyanine probe, to the clarifying of the peculiarities of the polynucleotide – low-molecular synthetic compounds (dyes) interaction. The absorbing, fluorescent and phosphorescent centers of styrylcyanines solutions and their complexes with DNA were identified. Two-photon excited fluorescence of benzothiazole, pyridin, indolinil dyes in DNA presence was registered, the two-photon absorbtion cross sections of dyes at wavelengths 1064 nm, 880 nm, 840 nm were evaluated. Manifestations of the triplet electronic energy transfer in DNA macromolecules were registered: quenching of the DNA phosphorescence in the presence of benzothiazole homodimer Dbos-30; delayed fluorescence (DF) and phosphorescence of dye bound with DNA upon excitation at DNAs’ absorbtion maxima wavelength. It was shown that DF was caused by the annihilation of the mobile migrating intra the DNAT-excitations on the probes-traps bound with this macromolecule. The average displacement of the electronic triplet excitation in DNA macromolecule was estimated as 70 А (that corresponds to the base pairs number between neighbor traps equal to 20) using dyes bound with DNA as traps for such excitations. It was shown that benzothiazole homodimer DBos-21 can be successfully used in TPE fluorescent microscopy of living cells to identify such specific subcellular organelles as mitochondria and nucleoli.