N. N. Glagolev

The effect of Pluronics on the photocatalytic activity of water-soluble porphyrins

Solubilization of hydrophilic porphyrins, 2,7,12,18-tetramethyl-3,8-di(1-methoxyethyl)-13,17-di(2-oxycarbonylethyl) porphyrin disodium salt (dimegin) and N-methyl-di-D-glucose amine salt of chlorine e6 (photoditazine), as well water-insoluble meso-tetraphenylorphyrin in the micelles of Pluronics (triblock copolymers and propylene oxide and ethylene oxide), increases the photocatalytic activity of porphyrins in the course of the oxidation of L-tryptophan in aqueous salt-containing solutions. The maximum photocatalytic activity is attained for the photocatalysts based on the Pluronics P85 and F127 containing 50–70% ethylene oxide units. As a result of solubilization, the activity of tetraphenylporphyrin increases by a factor of 50, while the activities of hydrophilic dimegin and photoditazine increase by factors of 1.5 and 6, respectively. The increased activity of tetraphenylporphyrin is due to the dissolution and dissociation of aggregates in the presence of Pluronics. The increased activity of dimegin, which is known to aggregate in water, is primarily provided by disaggregation. In the case of photoditazine, which does not form aggregates in aqueous solutions and is likely to be localized in the polar micellar “crown,” the effect of a polymer is due to the local concentration of both a substrate and a catalyst in the micellar pseudophase.

Combined laser and photodynamic treatment in extensive purulent wounds

Recently, photodynamic therapy (PDT) has been used for the treatment of festering wounds and trophic ulcers. An important advantage of PDT is its ability to affect bacterial cultures that are resistant to antibiotics. However the use of PDT alone does not usually guarantee a stable antiseptic effect and cannot prevent an external infection of wounds and burns. In this work attention is focused on the healing of the extensive soft tissues wounds with combined laser therapy (LT) and PDT treatment. At the first stage of this process festering tissues (for example spacious purulent wounds with area more than 100 cm2) were illuminated with high-energy laser beam (with power 20 W) in continues routine. The second stage involves “softer” PDT affect, which along with the completion stages of destruction pathological cells, stimulating the process of wound granulation and epithelization. Also, according to our previous results, photosensitizer (photoditazin) is introduced inside the wound with different amphiphilic polymers for increasing the PDT efficacy.

Amphiphilic polymers in photodynamic therapy

It is shown that some amphiphilic polymers (AP), including, polyvinylpyrrolidone (PVP), which exhibit no their own photochemical activity, can increase the activity of porphyrin photosensitizers (PPS), the most effective and nontoxic types of dyes for photodynamic action on tumor cells. It is also shown that, under the model conditions of tryptophan photooxidation, addition of amphiphilic polymers increases the activity of carborane-substituted tetra(fluorophenyl)porphyrins, Photoditazine, and dimegin. According to NMR and fluorescence spectroscopy data, this phenomenon, known as polymer effect, is probably associated with the formation of AP-PPS complexes, a factor that prevents the aggregation of PPS, normally occurring in aqueous solutions, thereby enhancing the photosensitizing activity of PPS.

The influence of ZnO-Sensor modification by porphyrins on to the character of sensor response to volatile organic compounds

The influence of modification of semi conductive ZnO and SnO2 sensors by porphyrins and their metal complexes on the parameters of sensor response to volatile organic compounds, ethanol, acetone and benzene, was analyzed. The concentration of volatile organic compounds (ci) varied in the range of 1–200 ppm. The sensor response was characterized by specific sensitivity γi = 100ΔRi/R0ci, where ΔRi = Ri − R0, Ri and R0 are measurable and initial resistance of the sensitive sensor layer correspondingly. It was established that the modification of sensors by porphyrins caused changes in sensor response and first of all decrease of ZnO sensor temperature at which the threshold of sensitivity is achieved (as used at this method cimin = 0.1 ppm) from 300 to 100°C. It also caused a change in sing of the parameter γ, which was of importance for creating “electronic nose” sensor systems. It was shown also, that the modification of ZnO sensor by metal complexes of porphyrin did not change sensor response parameters.

The character of the response of ZnO and SnO2 sensors modified with porphyrins to volatile organic compounds

The influence of the modification of the surface of ZnO and SnO2 sensors with 5,10,15,20-tetraphenylporphyrin on the parameters of sensor response to high-volatility organic substances was analyzed. The organic substances used were ethanol, acetone, and benzene. The sensor response was characterized by specific sensitivity γ determined as the ratio between a change in the resistance of the sensitive sensor layer and the volume concentration of high-volatility organic compounds introduced into the system. The modification of the sensors with tetraphenylporphyrin caused changes in sensor response, including a change in the sign of the γ parameter, which was of importance for creating “electronic nose” sensor systems.

Effect of parameters of a crosslinked polyacrylic matrix on the impregnation of photoactive compounds in supercritical fluids

The effect of the network density of spatially crosslinked polyacrylic transparent matrices and the conditions of their impregnation with a photochromic compound via the use of supercritical carbon dioxide on the concentration of the introduced photochromic compound of the spiroxazin family is studied. The concentration of impregnated filler in a matrix is shown to increase with increases in the interjunction distance (below a certain level) and network chain flexibility as well as with increases in the temperature and pressure of the impregnation process. Impregnation in rigid networks occurs only in surface layers, whereas, in an elastic network, impregnation occurs in the entire volume of a sample. Matrices based on oligourethanemethacrylates are characterized by a good thermodynamic affinity toward spiroxazin photochromic compounds, a fact that makes it possible to increase the concentration of photochromic compounds in the matrix up to 3 wt % under conditions of supercritical impregnation. The photochromic characteristics of an impregnated compound are shown to be preserved in samples.

Formation of long-lived fluorescent merocyanine forms of spiro compounds via their immobilization into polymer matrices from supercritical carbon dioxide medium

It is shown that the supercritical fluid (SCF) impregnation of polymers containing phenylphenol and halide polar groups (polycarbonate, fluoroplastic, poly(vinyl chloride)) with spiro compounds leads to conformational rearrangements resulting in stabilization of merocyanine forms of the photochromes. The effect of the formation of long-lived colored form B of the photochromes immobilized in the polymer matrix in SCF medium, revealed earlier for spinroanthroxazine, is of more general nature: it is observed and investigated by us for a number of spiro compounds SCF-impregnated into polar polymer matrices of different chemical structures. It was found that the colored forms of spiro compounds introduced in halogenated matrices feature intense photoluminescence.

Long-lived excited state of spiroanthroxazine after its matrix isolation in halogenated polyolefins by supercritical fluid impregnation

Supercritical fluid impregnation was used to perform matrix isolation of spiroanthroxazine (SAO) photochromic molecules in halogenated polymer films (polyvinylchloride and tetrafluoroethylene copolymer with vinylidene fluoride). An excited (colored) SAO form not relaxing to the ground (colorless) state was stabilized in polymers. Such a long-lived excited SAO form could exist as an isomer of the B form (B535 with an absorption band at λmax = 535 nm) in the fluorinated polymer matrix, for which the absorption maximum was shifted by more than 75 nm to the blue, and as the B form with a small admixture of the B535-form (in polyvinylchloride).

Photocatalytic properties and structure of chitosan-based porphyrin-containing systems

The photocatalytic activity of the disodium salt of substituted hematoporphyrin in a model reaction of tryptophan oxidation in the presence of chitosan with different molecular masses and a block copolymer of ethylene and propylene oxides (Pluronic F-127) is studied. It is shown that, in the presence of the Pluronic, the catalytic activity of the chitosan-porphyrin system increases. The structure of chitosan-Pluronic systems, depending on the molecular mass of chitosan and the presence of porphyrin, is examined by AFM. A pleasible mechanism of the influence of the Pluronic on the photocatalytic activity of chitosan-por-phyrin systems is proposed.

The photochromic properties of indoline spirooxazine-thermoplastic polymer systems obtained by supercritical fluid impregnation

The impregnation of thermoplastic polymers (polyethylene, polypropylene, polymethyl methacrylate, and polycarbonate) with photochromic compounds from the class of indoline spirooxazines in supercritical carbon dioxide (SC-CO2) was studied. The concentration of the photochrome and the kinetics of decolorization of its colored form depended strongly on the type of the polymer matrix and the structure of spirooxazine. The introduction of 1,3′,3′-trimethylspiro(indoline-2′,3-3H-anthraceno[2,1-b][1,4]oxazine) (SAO) into polycarbonate caused anomalous stabilization (the prolonged conservation of the excited colored form of SAO in the polymer matrix). In contrast to other photochrome-polymer pairs, after supercritical impregnation into polycarbonate, at least 10% of all SAO molecules were in the colored form, which was highly stable and did not decolorize after 150 days; the rest of the impregnated SAO molecules were localized in the matrix as individual molecules, partially colorized after matrix relaxation, or nanocrystals of characteristic sizes ∼10–20 nm. The mechanisms of the anomalous stabilization of the colored SAO form in the polycarbonate matrix are discussed.