The studies carried out in this work on the effective generation of singlet oxygen in the volume and on the surface of polytetrafluoroethylene (fluoroplastic-4, also known under the trade mark as Teflon) when irradiated with ultraviolet and visible radiation made it possible to clarify the mechanisms and features of the antiviral action of this fluoropolymer under specific experimental conditions.

The photodynamic inactivation of viruses by a microporous photocatalytic element made of copper or copper alloy is the very method of ensuring biosafety that the article is about. Based on this method, encouraging results of virological studies (using the influenza virus as a test) were obtained as well as the equipment solving the strategic task of antiviral (influenza, COVID-19, etc.) disinfecting and sterilizing of confined spaces air, including air of medical premises, was developed. Keywords: air sterilization, copper, microporous membrane, influenza virus, singlet oxigen.

Singlet oxygen together with radical reactions plays an important role in biochemistry of living organisms, and is one of the main active substances in photodynamic treatment of organs and body fluids. Along with traditional singlet oxygen photosensitizers based on biocompatible dyes, the singlet oxygen photogeneration ability of matrix materials such as organic solvents and metal oxide surfaces has recently been investigated. Despite a good compatibility with bio substances, polytetrafluoroethylene (also known under the trademark as Teflon (R)) remains unaddressed in these studies. Here we present our photoluminescence studies of singlet oxygen generation in polytetrafluoroethylene samples under ultraviolet and visible irradiation. We found a good singlet oxygen photogeneration with an efficiency no less and possibly exceeding it in carbon tetrachloride, a known single-t-oxygen-retentive medium. Based on the results obtained, it is assumed that the phosphorescence of singlet oxygen is observed from the volume of polytetrafluoroethylene with direct optical excitation of oxygen adsorbed or dissolved in the structure of polytetrafluoroethylene by analogy with direct optical excitation of oxygen in the volume of various solvents. Cooling a PTFE sample down to-20 degrees C allows to enhance the singlet oxygen concentration in the polymer indicating the enthalpy of oxygen sorption of Delta Hsorp =-1.51 kcal/mol. Our results can heighten medical interest to fluoropolymers and, in particular, to polytetrafluoroethylene making it a promising singlet oxygen generator for photodynamic uses.

The photodynamic inactivation of viruses by a microporous photocatalytic element made of copper or copper alloy is the very method of ensuring biosafety that the article is about. Based on this method, encouraging results of virological studies (using the influenza virus as a test) were obtained as well as the equipment solving the strategic task of antiviral (influenza, COVID-19, etc.) disinfecting and sterilizing of confined spaces air, including air of medical premises, was developed.

The processes of photoexcitation and energy transfer in an air-saturated solution of fullerene C60 in n-methylpyrrolidone are studied. With femtosecond laser pumping at a wavelength л(p) = 520 nm, transient absorption spectra were obtained in the range 470-750 nm. Broadband absorption is observed at л > 650 nm as a result of aggregation of fullerene molecules, characterized by a short decay time of the picosecond scale. The analysis of the time dependencies indicates the presence of several processes. Within the proposed interpretation, we state a remarkable reduction in the time of singlet-triplet intersystem crossing with an increase of nanocluster size while the rapid quenching of the singlet state varies only slightly. The quantum yield of the triplet state can therefore increase, reaching 0.14. The phosphorescence spectra of singlet oxygen with a maximum at л = 1276 nm were measured with LED excitation at various wavelengths in the range 370-625 nm. The lifetime and quenching rate constant of singlet oxygen in n-methylpyrrolidone are determined. The combined quantum yield of triplet fullerene and singlet oxygen in n-methylpyrrolidone is estimated as 0.74. The efficiency spectra of the singlet oxygen photosensibilization in the C60-(n-methylpyrrolidone)-oxygen system are obtained, indicating the increasing role of large nanoclusters in this process during aging of the solution.

In this work, a study of the photoluminescence of polytetrafluoroethylene (fluoroplast-4, also known under the trade mark as Teflon) in the near infrared region of the spectrum under its excitation by ultraviolet and visible radiation was carried out. It is shown that the photoluminescence spectrum observed from the surface of the fluoroplastic upon its excitation has a distinct characteristic luminescence profile, which coincides in its position with the phosphorescence spectrum of singlet oxygen.

The photostability of albumin complexes, Pluronic F-127 complexes and the aqueous solutions of photoditazine and dimegin were investigated. The photodegradation rate of albumin complexes was about four times faster than that of other compositions under study due to the desagregation of photosensitizers.

The influence of the properties of an aqueous medium on aggregation of dimegin, photoditazine, and radachlorin is comparatively studied. It is noted that the molar extinction nonlinearly depends on the concentration of photosensitizer in solution and the degree of nonlinearity is different for the pharmaceutical form of solutions and solutions prepared with the use of freeze-dried photosensitizer powders. It is shown that the use of surfactants (Pluronic F-127 and polyvinylpyrrolidone) somewhat reduces problems related to aggregation of photosensitizers under study.

AbstractThe photophysical properties of three photosensitizers—dimegine, photoditazine, and radachlorin—have been comparatively examined. For dimegine and photoditazine, two techniques have been used to measure the singlet oxygen generation quantum yields and the quenching constants of singlet oxygen by dimegine and photoditazine, as well as the dimegine fluorescence quantum yield.

A comparative study of the influence of an aqueous medium properties on the aggregation of dimegine, photoditazine and radachlorin was carried out. A nonlinear dependence of the molar extinction on the concentration of the photosensitizer in solution was noted, moreover to varying degrees for the dosage form of the solution and solutions prepared using lyophilized photosensitizer powders. It has been shown that the use of surfactants (Pluronic F-127 and polyvinylpyrrolidone) within certain limits reduces the problems associated with the aggregation of the studied photosensitizers.

AbstractWe compare the photostability of one porphyrin and two chlorine photosensitizers. We show that a higher photostability of dimegine compared to photoditazine and radachlorin is determined both by their different chemical natures and by the fact that the aggregation ability of porphyrin dyes is higher than that of chlorine dyes, which in the solution leads to efficient formation of dimers and higher-order complexes.

The spectral properties of singlet-oxygen luminescence at the 1 Δ g → 3 Σ g transition in the presence of rose Bengal as a photosensitizer are analyzed. The effect of iodine in solution in CCl 4 on the efficiency of singlet-oxygen generation and on the structure of singlet-oxygen luminescence is shown. The results of studies with tetrachloromethane are compared with the results obtained with other solvents.

We compare the photostability of one porphyrin and two chlorine photosensitizers. We show that a higher photostability of dimegine compared to photoditazine and radachlorin is determined both by their different chemical natures and by the fact that the aggregation ability of porphyrin dyes is higher than that of chlorine dyes, which in the solution leads to efficient formation of dimers and higher-order complexes.

Выполнен анализ спектральных свойств люминесценции синглетного кислорода на переходе 1 g → 3 g с применением красителя бенгальского розового в качестве фотосенсибилизатора.Показано влияние йода в растворе в

This paper presents a review of papers associated with the study of in vitro spectral, fluorescence, and photosensitizing properties, as well as the photostability of low-toxicity photosensitizers based on endogenous porphyrins—the disodium salt of 2,4-di(1-methoxyethyl) deuteroporphyrin IX (dimegin) and the tetrapotassium salt of coproporphyrin III—in comparison with chlorin preparations for medical purposes—Photoditazin, Radachlorin, and Fotolon—when photosensitizer solutions are irradiated in the visible range. The influence of transport additives and proteins on the properties mentioned above is discussed and studied. The results of the study are evidence that it is promising to use drugs based on endogenous porphyrins as effective agents for photodynamic therapy and fluorescence diagnosis, where, along with the photophysical properties of the photosensitizer, a key role is played by photostability, low toxicity, and accumulation selectivity in the pathological foci of the organism, and this is directly associated with the chemical structure of the drug. The results of the latest work carried out at S. I. Vavilov State Optical Institute on this specialization are treated separately.

The photophysical properties of three photosensitizers—dimegine, photoditazine, and radachlorin—have been comparatively examined. For dimegine and photoditazine, two techniques have been used to measure the singlet oxygen generation quantum yields and the quenching constants of singlet oxygen by dimegine and photoditazine, as well as the dimegine fluorescence quantum yield.

The photocatalytic activity of some metal oxides and sulfides, as well of С 60 fullerene, is compared using the method of photocatalytic degradation of methylene blue simultaneously with comparison of the efficiency of methylene blue adsorption on solid-phase powders of these oxides, sulfides, and fullerene in aqueous solution of the dye in the absence of irradiation.