Luminescence kinetics of two-component molecular systems in porous glasses

The kinetics of bimolecular photoreactions accompanied by a characteristic delayed emission of reactant molecules is studied in nanoporous silica glasses upon selective activation of a two-component luminophore system (erythrosine-anthracene) by a short (10 ns) pulse of a Nd³⁺:YAG laser (532 nm). Time-resolved luminescence signals with different shapes are recorded in different spectral regions. The emission at a wavelength of 430 nm is identified as the sensitized delayed annihilation fluorescence of anthracene. The long-time luminescence in the region of 570 nm consists of thermally induced delayed fluorescence of erythrosine and an emission resulting from heterogeneous annihilation of triplet excitations of erythrosine and anthracene. The effect of pore sizes on the triplet-triplet energy transfer efficiency is determined.     

Effects of the magnetic field and zinc isotopes on the colony forming ability and elemental composition of E. coli bacterial cells

Russian Chemical Bulletin - The combined effects of external weak magnetic fields and nuclear spins of the magnetic isotope 67Zn on vital functions of E. coli bacterial cells were proved...     

Enzymatic mechanisms of biological magnetic sensitivity: nuclear spin effects

Intracellular enzymatic reactions involving ion-radical states are shown to act as a universal mechanism of magnetically sensitive living organisms. Weak magnetic fields can affect the rate of intracellular enzymatic reactions. The main magnetically sensitive stage is the singlet-triplet conversion of ion-radical pairs in the active sites of enzymes induced by Zeeman and hyperfine interactions of electron and nuclear spins. The participation of a nuclear spin in the ion-radical process results in a strong dependence of the enzymatic reaction rate in weak magnetic fields comparable with the magnetic field of the Earth.     

A study of the interaction of rhodamine 6G with DNA by spectrophotometry and probe microscopy

The interaction of rhodamine 6G with DNA was studied by the methods of spectrophotometry and scanning probe microscopy. It was ascertained that rhodamine 6G interacts with the DNA macromolecules by cooperative binding to the exterior surface of the polymeric chain. As a result, organic nanostructures form on the surface of the polymers. The number of dye molecules in the nanostructures is estimated. The distribution of these structures along the double helix of DNA and their merging into larger conglomerates is studied.     

Optical properties of nanoplasmon excitations in clusters of endometallofullerenes

The optical properties of solutions of endometallofullerenes with lanthanides (Gd@C₈₂, Ce@C₈₂, La@C₈₂, Y@C₈₂) in dimethylformamide are studied. It is found that these solutions luminesce in the visible region. This luminescence is accompanied by enhanced Raman scattering. It is suggested that these processes are related to nanoplasmon excitations in clusters of endometallofullerenes. It is shown that the luminescence spectrum is described by a superposition of three to four Gaussian spectral profiles, whose energy positions and intensities nonmonotonically depend on the energy of excitation quanta. A detailed quantitative dependence of the intensity and shape of the Raman scattering signal on the concentration of endometallofullerenes in the solutions is determined. Comparative measurements are performed for the emission spectra of solutions of simple fullerenes and chromatographically pure endometallofullerenes. Complex investigations show that the visible luminescence and Raman scattering enhancement are only observed in the case of the formation of nanosized anionic complexes of endometallofullerenes in the solution.     

Long-term luminescence of organic dyes in cells of biological tissues

We studied the kinetics of delayed fluorescence and phosphoresce of exogenous fluorophores in cells extracted from tumorous and normal tissues of the mammary gland of mice of the BYRB strain. We revealed the specifics and determined regularities of the kinetics of long-term luminescence of fluorophores in different cells. The possibility of developing of a method for the early fluorescence diagnostics of the pathology of biotissues based on the obtained results is discussed.     

Spectroscopic properties of DNA-acridine orange biopolymer films

Using electronic absorption, luminescence, and vibrational spectroscopy, we study the properties of DNA-acridine orange biopolymer films. The conformational structure of DNA molecules in the film is examined at different levels of the relative humidity, and the state of dye molecules incorporated into the structure of the biopolymer is estimated. These structures were formed according to the “guest-host” principle and the dye molecule acts as the “guest” and the “host” is the intercalative DNA binding sites. In such system dye molecules demonstrate high luminescence capability and are the uniform optical centers and their fluorescence spectrum doesn’t depend on excitation wavelength.     

Photophysics of Semiconductor Polymer Nanocomposite with Fullerene C60 and Endohedral Metallofullerene Ho@C82

Physics of the Solid State - The photoexcitation energy transfer in donor–acceptor (DA) systems formed from a mixture of semiconductor polymer...     

Long-term luminescence of sensibilizers in tissues at the conditions of oxygen deficiency due to photodynamic effect

Long-term luminescence of organic dyes (xanthene dyes, halogen substituted fluoroscein) was used for an in vitro study of the photodynamic effect of exogenic probes in malignant tumors and healthy tissues of mice. It is shown that the photodynamic activity of oxygen and the dynamics of its concentration in tissues can be estimated from the delayed fluorescence of exogenic probes caused by singlet–triplet annihilation of singlet oxygen and excited triplet states of the molecules of photosensitizer dyes. It is found that quenching of long-term luminescence of photosensitizers significantly differs in tumors and normal tissues.