The interactions of two metal-free phthalocyanines [(H2Pc) and Solar Pc (with four peripherical groups: SO2N(CH2CH2OH)2)] and of one metal substituted dye (CoPc) with resting and stimulated human peripheral blood mononuclear cells (PBMC) were compared. The absorption, fluorescence, photoacoustic and EPR spectra of both resting cells and cells stimulated by phytohaemagglutinin, incubated in dimethyl sulfoxide (DMSO) with very low or 95% water content and with or without dye addition, were measured. The fate of the light absorbed by the samples was investigated. It is known that singlet oxygen production is crucial for photodynamic action of dyes. Thermal deactivation and luminescence emission compete with this process, so investigation of these alternative paths of sensitizer deactivation provides information about photodynamic action. The incorporation of the investigated dyes into cells and the perturbation of the cell structure caused by the dyes, the incubation solvent and the activator were investigated by comparing the spectral properties of PBMC before and after stimulation and incubation. Incubation of the cells for 1 h in a solution of Solar Pc in 99.5% aqueous DMSO, resulted in an efficient dye incorporation which was highly selective. Solar Pc being introduced much more efficiently into stimulated cells than into resting cells.
Four various phthalocyanines dyes were oriented in uniaxially stretched polymer films. Polarized absorption, fluorescence, and photoacoustic spectra were measured. From a stepwise reduction procedure, the orientation of molecules with respect to the film stretching direction as well as the orientation of absorption transition moments vectors with respect to molecular skeleton of dye were evaluated. The complexation with various metals and the attachment of side groups to the phthalocyanine ring change the orientations and interactions of the dye molecules with polymer chains. Two bands, B1 and B2, with different orientations of their absorption transition moments were found in the short wavelength spectral region. The obtained results were discussed on the ground of literature data and compared with our previously gathered results concerning the possible application of investigated dyes in photodynamic therapy.
Human peripheral blood cells stimulated by phytohemagglutinin (which serve as a model of cancerous cells) and resting cells were incubated in dimethyl sulfoxide solutions of various phthalocyanines. In order to diminish the influence of atmospheric oxygen the cells were embedded in a polymer (polyvinyl alcohol) film. Fluorescence spectra of the samples were measured over two regions of excitation wavelengths: at 405 nm (predominant absorption of the cell material) and in the regions of strong absorption of phthalocyanines (at about 605 nm and 337 nm). The intrinsic emission of cell material became changed as a result both of cells' stimulation and of incubation of cells in dye solution. In most cases the stimulated cells when stained by dye exhibited higher long wavelength fluorescence intensity than resting cells. This suggests higher efficiency of dye incorporation into cancerous cells than into healthy cells. The absorption spectra of samples were also measured. The spectra of various phthalocyanines in incubation solvent, in polymer and in the cells embedded in polymer, were compared. The comparison of properties of the cells stimulated for different time periods enabled to establish the conditions of stimulation creating a population of cells incorporating a large number of sensitizing molecules.
The time-resolved photothermal methods are used in order to establish the yield of intersystem (singlet-triplet) crossing of dyes that are candidates for the application in photodynamic therapy. It is known that molecules with long living triplet state cause efficient photosensitization by direct interaction with the cells or by singlet oxygen generation.The steady state photoacoustic spectra enables one to establish the dye incorporation into cells.Both methods were applied to several phthalocyanines and the results gathered by photothermal measurements were compared with the results obtained by means of other methods.The six investigated dyes were compared.
Three phthalocyanine dyes-sensitizers were incorporated into two types of human T leukemia cells from two cell-lines: CCRF and MOLT 4. The efficiency of the dye incorporation into cells and photochemical properties of stained cells were investigated using fluorescence spectroscopy. The dyes exhibited different properties in each of the two cell-lines. Small differences in cell membrane properties have a strong influence on the efficiency of dye incorporation and on the course of photodynamic reaction. It is suggested that, for a given patient, an optimal dye-sensitizer should be established before photodynamic treatment.
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