Intermolecular interactions between natural humic substances and tricyclic antidepressants

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Dynamics of photosensitized singlet oxygen generation and photophysical characteristics of chlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript> in photolon ointment

We have used luminescence and absorption spectroscopy to study the dynamics of photosensitized singlet oxygen generation and the photophysical characteristics of chlorin e ₆ in Photolon ointment. We have shown that dimethylsulfoxide and polyethylene glycol 400, in concentrations comparable with their content in the ointment form of the drug Photolon, do not lead to appreciable changes in the spectral characteristics of chlorin e ₆. Substantial changes in the photophysical characteristics of the photosensitizer are observed at significantly higher concentrations of the excipients in the ointment. We have shown that in buffer solution, chlorin e ₆ forms a complex with polyethylene glycol 1500. For the first time, we have detected luminescence of singlet oxygen from the surface of biological tissue treated with Photolon ointment.     

Quantum yield and rate constant of the singlet <Superscript>1</Superscript>Δ<Subscript><Emphasis Type="Italic">g</Emphasis></Subscript> oxygen luminescence in an aqueous medium in the presence of nanoscale inhomogeneities

The quantum yields and lifetimes of photosensitized luminescence of the ¹Δ _g state of singlet oxygen in an aquatic media with a controlled concentration of dielectric anisotropy centers (polyethylene glycol) have been measured using the methods of laser fluorometry. It is established that the quantum yield and the rate constant (k _r ) of the a ¹Δ _g → X ³Σ _g ^- luminescence of ¹O₂ increase as the polymer concentration increases. The effect is analyzed within a general approach involving a relationship between kr and dielectric properties of the medium and is explained by the increased density of photon states and the local field factor in the space around O₂(а ¹Δ _g ).     

Effect of a Homogeneous Dielectric Medium on the Luminescence of Singlet Oxygen

Russian Physics Journal - Results of an analysis of our and literature data devoted to the study of the effect of a homogeneous dielectric medium on the rate constant of the $$...     

Raman spectra of tetrapyrrole photosensitizer chlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript> and their interpretation

The resonance and surface enhanced Raman scattering (SERS) spectra of chlorin e 6 trisodium salt in aqueous solutions, solid films, and adsorbed on the silver-coated surface of porous silicon are presented. Using the quantum-mechanical density functional method, the geometric structure and vibrational frequencies of the chlorin e ₆ molecule are calculated and the Raman spectrum of this molecule is interpreted for the first time. The geometry of sorption of chlorin e ₆ on the surface of a nanostructured silver film is considered based on a comparative analysis of the resonance Raman and SERS Raman spectra in the approximation of a short-range mechanism of Raman scattering enhancement.     

Photoinduced Breaking of the Fe–O2 Bond in Hemoglobin: Dissociation Quantum Yield,Excited Electronic States,and Nonradiative Relaxation Processes

Optics and Spectroscopy - Bimolecular recombination of molecular oxygen with human hemoglobin upon excitation in different spectral ranges is studied by nanosecond laser kinetic spectroscopy. The...     

Dynamics and efficiency of the photosensitized singlet oxygen formation by chlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript>: The effects of the solution pH and polyvinylpyrrolidone

The effects of the solution pH and polyvinylpyrrolidone on the dynamics and efficiency of the formation of singlet oxygen ¹O₂ in buffer media (pH 6.3–8.5) photosensitized by chlorin e ₆ are studied. It is demonstrated that the quantum yield of the ¹O₂ formation photosensitized by chlorin e ₆ decreases with decreasing solution pH due to the aggregation of photosensitizer molecules. Polyvinylpyrrolidone facilitates the disaggregation of chlorin e ₆, thus increasing its photosensitizing ability. For a complex of chlorin e ₆ with this polymer, the luminescence kinetics of singlet oxygen is inverted, which should be taken into account in the determination of the lifetime of ¹O₂ in real biological systems.     

Dependence of the spontaneous emission of singlet oxygen on the refractive index and molecular polarizability of the surrounding dielectric media

The rate constants (k _r ) for singlet oxygen O₂ (a ¹Δ _g ) luminescence in several selected solvents and in binary solvent mixture (acetone-toluene) were measured. All data have been normalized such that k _r ^rel = 1.0 in toluene. It has been demonstrated that the changes in these rate constants were caused both by optical properties of a medium (the local field factor and density of photon states) and by an inherent property of the emitter of ¹O₂ (the square of transition moment). In its turn, the value of the transition moment is directly proportional to molecular polarizability of the medium molecules.