Cytotoxical effect of a pulsed laser irradiation in presence of nanoparticles of carbon black, sulphuretted carbon and
fullerene-60 on death of human uterus nick cancer HeLa and mice lymphoma P 388 cells was studied in vitro. Bubbles
formation as result of "microexplosions" of nanoparticles is one of possible mechanisms of this effect. Other possible
mechanism is cytotoxical products formation in result of pyrolysis of nanoparticles and biomaterial which is adjoining.
The cytotoxical effect of addition of a supernatant from the carbon nanoparticles suspensions irradiated by the pulsed
laser was studied to test this assumption. Analysis using gas chromatograph determined that carbon monoxide is
principal gaseous product of such laser pyrolysis. This is known as cytotoxical product. Efficiency of its formation is
estimated.
Photodynamic therapy with saturating of photochemical dose (PD) using three different techniques was studied theoretically. At saturation PD does not depend on the light fluence and is determined by concentration of photosensitizer or oxygen.
The photodynamic therapy with saturating of photochemical dose (PD) using three different techniques was studied theoretically. At saturation the PD value does not depend on the light fluence and is determined by concentration of photosensitizer or oxygen. The possibility of creating more uniform therapeutic dose distribution throughout a tumor is shown.
Photodynamic therapy (PDT) wit h total photobleaching of a photosensitizer (PS) was studied theoretically. The equations for spatial-temporal distribution of photochemical dose (PD) under various irradiations were obtained. Both surface irradiation and interstitial irradiation were considered. The possibilities of having constant therapeutic dose within a large extent of a tissue and even of obtaining the maximal dose at a particular depth were shown.
Oxygen is the limited component in PDT, especially in the hypoxic tissues. Proteins and amino acids are the main oxidation substrates in tissues in the case of singlet oxygen while, for example, hydroxy radicals well oxidize also DNA and membrane lipids which are considered as the critical targets in PDT. We compared the quantum yields of the oxygen consumption by Type I and by Type II mechanisms in the aqueous solutions in the comparable with PDT conditions. The preparation Photosens was used as photosensitizer, human albumin serum-as oxidation substrate, and sodium ascorbate-as reductant. We conclude that the oxygen consumption proceeds mainly by Type II mechanism while PDT efficiency by Type I mechanism can be even higher.
The optical sensor based on the dependence of the phosphorescence lifetime of palladium meso- tetraphenyltetrabenzoporphine on the oxygen concentration was developed. The polystyrene film doped with the dye is deposited on the tip of the fiber wave-guide (d=190 micrometers ) placed in medical needle (d=330 micrometers ). As an excitation source He-Ne laser is used with power 50 mW. The rectangular excitation pulses (pulse durability is of 20 microsecond(s) , durability of fronts- not higher than 1 microsecond(s) , pulse repetition is 0.5-1 Hz) are formed using mechanical obturators and are introduced in wave-guide. The outgoing back from wave-guide phosphorescence radiation is registered using photo detector. The formed electrical signal is processed using computer. The sensor is suitable for invasive oxygen tension measurements. The kinetics of the tumor oxygenation during light irradiation in photodynamic therapy (photosensitizer- sulphonated aluminium phthalocyanine) as well as of the oxygen consumption rate in the catalytic oxidation of sodium ascorbate in the aqueous buffer solution (pH=7.4) in presence of cobalt octacarboxyphthalocyanine as the catalyst are presented.
It is well known that sulphophthalocyanine derivatives under laser irradiation induce photochemical reaction of II type with generation of cytotoxic agent - singlet oxygen. The combination of phthalocyanine and exogenic reductant - sodium ascorbate may also induce other reactions, involving the formation of free radicals, and thus intensify the antitumor effect. To improve the results of PDT we used the additional injection of sodium ascorbate, the hyperbaric oxygenation and different regimes of laser irradiation. We conducted the experimental study on 100 white mice with Erlich carcinoma. Macroscopic and microscopic data showed that sodium ascorbate significantly increases the effect of PDT in comparison with control group due to the higher tumor damage, vascular alterations, inhibition of cell proliferation and stimulation of antitumor desmoplastic reaction.
It was found that irradiation of aqueous solution of aluminum sulphophthalocyanine (SnPcAl) by light with wavelength of 805 nm in the presence of sodium ascorbate results in photodynamic type I effect. S2PcAl in adsorbed state on proteins or polysaccharide structures was shown to possess rather intense long wavelength absorption band in the NIR spectral region. The comparative tests of SnPcAl with sodium ascorbate on mice with Ehrlich carcinoma and leucosis P-388 showed that photodynamic efficiency in the case of NIR irradiation (790 nm) is not lower than using visible irradiation (675 nm).
It is well known that sulphophthalocyanines induce in process of PDT photochemical reaction of II type with generation of cytotoxic agent -- singlet oxygen. The combination of phthalocyanine and exogenic reductant -- sodium ascorbate may also induce other reactions, involving the formation of free radicals, and thus intensify the antitumor effect. The mechanism of action of the ascorbate may be connected also with the direct tumor cells damage (apoptosis) and with the stimulation of antiblastome resistance. We conducted the experimental study on 150 white mice with Erlich carcinoma. Macroscopic and microscopic data showed that ascorbate significantly increases the effect of PDT in comparison with control group due to the higher tumor damage, inhibition of its growth and stimulation of antitumor desmoplastic reaction.
We have determined the efficacy of PDT and depth of necrosis for advanced tumors. Clinical results of PDT have shown that it is possible to get the depth of tumors necrosis till 20 mm using lasers providing high power density of laser irradiation. One of the possible models can be enlightenment of sensitizer during laser irradiation.
The kinetics of oxygen consumption in aqueous solutions of sulphonated hydroxyaluminum phthalocyanine and protein under irradiation with He-Ne laser was studied using the method of sensitizer fluorescence saturation. The constants of triplet state quenching were determined. The dye is oxidized with superoxide anion-radical, whereas the protein -- mainly by singlet oxygen.
Method of measurement of basic parameters for intramolecular transitions in organic compounds solutions is discussed. The values of triplet quantum yield and lifetimes for a number of solitons of the phthalocyanine derivatives and related compounds have been measured. The possibility of measurement of intramolecular parameters and dissolved oxygen concentration was shown on an example of aqueous solutions used in clinic for diagnostics and photodynamics therapy of cancer.
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