The results of experimental and theoretical studies into the optical characteristics of a new indotricarbocyanine dye are
presented indicating that this dye shows much promise as an effective (nonlinear) power limiter for laser radiation in the
visible. The luminescent and energy characteristics of the dye molecules are experimentally studied, and the absorption
spectra are given with nanosecond resolution. The electronic absorption spectra for the ground (S0→Sn) and excited
(S1→Sn) states are calculated using the quantum-chemical methods. A nature of the electronic state of the molecule
under study is established, and a rate constant of the intramolecular processes is determined. The theoretical results
coordinate well with the experimental data. The investigated dye reveals singlet-singlet absorption in the region 400-600
nm. Excitation of the dye is realized by the second harmonic radiation of a Nd-YAG laser. The Z-scan method with the
open diaphragm is used to determine the absorption cross-section of indotricarbocyanine dye upon 532 nm excitation.
The nonlinear absorption characteristics of the given molecule are compared to the earlier results obtained for other
polymethine dyes.
The paper presents recent experimental results on the peculiarities of fluorescence and transient absorption exhibited by indotricarbocyanine dyes in solutions of different nature. The dynamics of transient absorption spectra of the molecules under study is analyzed within the framework of the concept of intra- and intermolecular vibrational relaxation and ultrafast charge transfer in contact ion pairs.
In this paper we describe a compact, portable light-emitting diode (LED)-based fiber-optic system allowing in vivo diffuse reflectance spectra registration in visible and near IR spectral range at two distances between illuminating and collecting fibers. The construction of fiber optic probe is adapted for endoscopy application. We further report the preliminary results of in vivo discrimination between of the benign and malignant tissues and different types of malignant tissues in the animal models.
Investigation of the spectral properties of polymethine dyes in organic solvents, water, nutritious media and cell cultures at various concentrations has demonstrated that the tumor cells contain monomers of the dye molecules. Pharmacokinetics of the different dyes has been studied both in vivo and in vitro. After incubation of a cell culture in the presence of a nontoxic does of the dyes their concentration in tumor cells is rather high, varying for different preparations from 10-11 2.1 10-9 mol per million cells. The biggest phototoxicity in vitro has been observed for polymethine dyes with indolenine end groups. In vivo concentration of the dyes in tumor tissues was higher than in normal muscle tissues ranging from 1.2 to 3.6 for different kinds of tumor. Photo bleaching of dyes during photodynamic treatment was observed. The photodynamic treatment with some polymethine dyes caused tumor tissue necrosis up to 20 mm in depth.
Investigated polymethine dye TICS has near IR bands of fluorescence and absorption within the transparency region of biological tissues. It can be detected up to 1.5 cm from the surface of the skin. The intensity of a fluorescence signal of TICS is linear for doses up to 2 mg/kg in both tumor and muscle tissue. The ratio of an intensity of light induced fluorescence in tumor tissue to one in muscle tissue is up to 3.6 for rapidly growing tumors. The retention time of TICS is 7 days in all tissues. TICS can be used in the detection of tumor boundaries and tumor internal structure.
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