Indotricarbocyanine Dye Research Articles

Spectral and kinetic parameters of photoexcited complexes of albumin and indotricarbocyanine dye with phosphonate substituents

Spectral and kinetic parameters of photoexcited complexes of albumin and indotricarbocyanine dye with phosphonate substituents

Fluorescence Diagnosis of Damage to Tumor Tissues During Photodynamic Therapy with the Photosensitizer Photolon®

We have studied the feasibility of using an indotricarbocyanine dye as a marker for the efficacy of photodynamic therapy (PDT) of cancers with the photosensitizer Photolon®. We have established that on exposure to laser emission at λ = 667 nm with an exposure dose of 100 J/cm2, we observe that the Photolon® concentration drops by about a factor of two in the exposed part of the tumor, while the concentration of the indotricarbocyanine dye does not change in any region of the tumor node. We have observed a correlation between the change in the shape of the fluorescence spectra of the indotricarbocyanine dye in vivo in the 780–880 nm resulting from a PDT session with the photosensitizer Photolon® and the extent of damage to the tumor tissues. Changes in the shape of the fluorescence spectrum of the dye are interpreted in terms of a model involving the appearance of absorption by different forms of hemoglobin, and changes in their ratio in the exposed part of the tumor due to consumption of molecular oxygen.

Novel indotricarbocyanine dyes covalently bonded to polyethylene glycol for theranostics

Abstract The synthesis methods for the indotricarbocyanine dyes covalently bonded to polyethylene glycols with varying degrees of polymerization have been developed. New indotricarbocyanine was synthesized in one step using the Mukayama reagent in polyethylene glycol with cesium fluoride as a basic catalyst. In vivo investigation of the phototherapeutic dye activity has shown selective recognition of malignant tissues, where accumulation of the dye was 4–5 times higher than in normal tissues. The necrotic area after local photoirradiation at the effective energy fluence 180 J/cm 2 , λ = 780 nm was observed to a depth of 2.5 cm making the synthesized dyes very promising for further pharmaceutic research.

Infrared fluorescent markers for microarray DNA analysis

In order to expand the informational capabilities of molecular genetic research, new indotricarbocyanine dyes that fluoresce in the near infrared (IR) spectral region have been synthesized. The developed IR dyes were studied using a biochip-based test system for detection of mutations in the BRCA1/BRCA2 and CHECK2 genes associated with breast cancer. The fluorescent label was introduced to the analyzed DNA during PCR using primers labeled with the synthesized IR dyes. An analyzer that allows recording and processing of images of fluorescent microarrays in the IR spectral region was designed and manufactured. It has been shown that the use of the synthesized dyes enables to conduct analysis in the IR region and improve the reliability of medical diagnostic tests due to low fluorescence intensity of sample components as well as of a biochip substrate and the reagents used for analysis.

Флуоресцентные метки инфракрасного диапазона для анализа ДНК с помощью биологических микрочипов

To expand the informational capabilities of molecular genetic research, on the biological microchips, new indotricarbocyanine dyes that fluoresce in the near infrared (IR) spectral region have been synthesized. The developed IR dyes were studied using a biochip-based test system for detection of mutations in the BRCA1/BRCA2 and CHECK2 genes associated with breast cancer. The fluorescent label was introduced to the analyzed DNA during PCR using primers labeled with the synthesized IR dyes. An analyzer that allows recording and processing of images of fluorescent microarrays in the IR spectral region was designed and manufactured. It has been shown that the use of the synthesized dyes enables to conduct analysis in the IR region and improve the reliability of medical diagnostic tests due to low fluorescence intensity of sample components as well as of a biochip substrate and the reagents used for analysis.

Concentration Increase of the Singlet-Oxygen Generation Quantum Yield by an Indotricarbocyanine Dye

Regularities in the generation of singlet oxygen sensitized by the indotricarbocyanine dye HITC with I– and ClO4 – anions in highly and slightly polar solvents were studied as functions of dye concentration (Cd). The yield of singletoxygen formation (γΔ) by HITC (I–) increased in slightly polar solvents as its concentration increased. It was shown that HITC with Cd < 10–7 M in CHCl3 and <5·10–6 M in o-dichlorobenzene with any anion was found primarily in the form of free ions. It was established that the concentration increase of singlet-oxygen generation by HITC (I–) was due to the heavy-atom effect of the anion as a result of their existence as contact ion pairs and an increase of the fraction of such pairs in a solution with an increased photosensitizer concentration. The quantum yield of singletoxygen formation for HITC with ClO4 – counterion was stable in various solvents as Cd was varied over a wide range.

Photophysical and photochemical properties of HITC indotricarbocyanine dye molecules in solutions

Results of studies on the photonics of HITC indotricarbocyanine dye molecules with I–, Br–, and ClO4 – counterions were presented. Introduction of an additional salt (tetrabutylammonium bromide) (10–2 M) to slightly polar solutions of the tricarbocyanine dye was shown to cause significant changes in the dye photophysical and photochemical characteristics. It was concluded based on a comparison of HITC dye photophysical properties with I–, Br–, and ClO4 – counterions in slightly polar dichlorobenzene and highly polar EtOH; an analysis of trends in HITC photobleaching in deoxygenated and air-saturated solutions; and data from femtosecond spectroscopy that the features of the photophysical and photochemical processes in slightly polar dichlorobenzene were due to superfast charge transfer in tight ion pairs followed by formation of free radicals.

Near-infrared heptamethine cyanine dyes. Synthesis, spectroscopic characterization, thermal properties and photostability

Abstract Near-infrared heptamethine cyanine dyes were synthesized without substitution to the polyene chain but with various substituents on the indoleninium fragments. To develop indotricarbocyanine dyes with improved photochemical characteristics, we studied the relationship between the structures of these compounds, their spectral properties, their photostability, and thermal stability.

Fluorescence of a photosensitizer based on an indotricarbocyanine dye in photochemotherapy

We present the results for studies of the spectral luminescence properties of a symmetric indotricarbocyanine dye (PD1) in HeLa tumor cells and animal tissues in vivo during a photochemotherapy session and after the end of the session. We have established that when the dye is exposed to light in tumor tissues, changes occur in the position and half-width of the dye fluorescence spectra, while in a culture of HeLa cells its spectral characteristics are constant. Based on analysis of the effect of overlap between the absorption spectra of endogenous biomolecules and the fluorescence spectra of the dye plus comparison of the experimental data with numerical modeling results, we have concluded that the observed changes in the fluorescence spectra of PD1 in vivo are due to a change in the ratio of the different forms of hemoglobin in the tumor tissue. We have shown that the spectral characteristics of PD1, fluorescing in the near IR range, correlate with the depth of tumor tissue necrosis achieved on exposure to light. We have established that tumor tissue necrosis occurs down to a depth of 2 cm in the case of all strains studied: S-45, SM-1, and W-256, where as a result of exposure to light, we observe an increase in the half-width and a short-wavelength shift of the fluorescence spectrum of the dye PD1, and also the intensity of its fluorescence does not recover.

Cyanine dyes as contrast agents for near-infrared imaging in vivo: acute tolerance, pharmacokinetics, and fluorescence imaging

We compare pharmacokinetic, tolerance, and imaging properties of two near-IR contrast agents, indocyanine green (ICG) and 1,1(')-bis-(4-sulfobutyl) indotricarbocyanine-5,5(')-dicarboxylic acid diglucamide monosodium salt (SIDAG). ICG is a clinically approved imaging agent, and its derivative SIDAG is a more hydrophilic counterpart that has recently shown promising imaging properties in preclinical studies. The rather lipophilic ICG has a very short plasma half-life, thus limiting the time available to image body regions during its vascular circulation (e.g., the breast in optical mammography where scanning over several minutes is required). In order to change the physicochemical properties of the indotricarbocyanine dye backbone, several derivatives were synthesized with increasing hydrophilicity. The most hydrophilic dye SIDAG is selected for further biological characterization. The acute tolerance of SIDAG in mice is increased up to 60-fold compared to ICG. Contrary to ICG, the pharmacokinetic properties of SIDAG are shifted toward renal elimination, caused by the high hydrophilicity of the molecule. N-Nitrosomethylurea (NMU)-induced rat breast carcinomas are clearly demarcated, both immediately and 24 h after intravenous administration of SIDAG, whereas ICG shows a weak tumor contrast under the same conditions. Our findings demonstrate that SIDAG is a high potential contrast agent for optical imaging, which could increase the sensitivity for detection of inflamed regions and tumors.

Spectral luminescence properties of indotricarbocyanine dye in biological tissues

We have established that the shape and position of the maximum in the fluorescence spectrum of an indotricarbocyanine dye in tumor and normal tissues in vivo change over time after intravenous injection of the dye. Based on analysis of the spectral properties of the dye in vivo and in blood plasma, the dependence of the properties on the time since injection has shown that in the living body, the environment of the dye molecule changes as the photosensitizer goes from the skin into the tissue. We have established that in tissues in vivo, the dye molecules are localized in a region with low dielectric constant of the medium. We have shown that the change in the ratio of the concentrations of the different forms of hemoglobin in the blood has an effect on the absorption and shape of the fluorescence spectrum of the dye in tissues in vivo.

Fast photoprocesses in a symmetric indotricarbocyanine dye (HITC) in solutions

Spectral-kinetic and photochemical properties of HITC dye with iodide and perchlorate counterions have been studied in environments where the dye molecules exist in different ionic forms. In ethanol, the dye molecules exist as free ions; in dichlorobenzene, as contact ion pairs. Superfast transformation of non-stationary spectra in an HITC dye bleaching band is found. The observed effects are interpreted within the framework of concepts on “burning out” a notch in the contour of a non-uniformly widened vibronic band of S 0 → S 1-absorption. Qualitative differences in recorded absorption spectra from the dye excited electronic states for weakly and highly polar solvents are found. It is shown that the observed differences are caused by superfast charge transfer in the contact ion pairs that results in the formation of free radicals.

Influence of photon energy on the efficiency of photochemotherapy

It is found that when indotricarbocyanine dye in HeLa cells is exposed to photons with different energies the efficiency of cell damage is wavelength independent provided the photosensitizer absorbs the same number of photons per unit time. In vivo animal experiments with two strains of tumor show that when the wavelength of the irradiating light is increased (668, 740, and 780 nm) and the number of photons absorbed per unit time per unit volume of the tumors is held constant, the damage depth increases by a factor of 1.5 and 3, respectively. The observed changes are related both to differences in the in vivo tissue optical transmission with increasing wavelength and an increased local concentration of oxygen owing to photodissociation of oxyhemoglobin.

Generation of singlet oxygen by indotricarbocyanine dyes in low-polarity media

We present the results of a study of the spectral luminescence properties of three groups of indotricarbocyanine dyes, each of which is formed from compounds with the same cation and different anions. In high-polarity solvents, in the absorption and emission spectra of the dyes we see one type of center; in low-polarity solvents, due to the presence of different ionic forms of the dyes (free ions, contact ion pairs), we observe either one type or two types of centers. By analysis of the luminescence of molecular oxygen in the 1.27 µm spectral region, we determined the efficiency of photosensitization of 1O2 formation by dyes in deuterated solvents. We have shown that in low-polarity solvents, the yield for singlet oxygen generation is higher for indotricarbocyanine dyes which are found in the contact ion pair state and which also contain a heavy atom (I) in the anion. We have observed that an increase in the fraction of contact ion pairs in solution as the dye concentration increases or when an additional salt is introduced leads to an increase in the quantum yield for generation of singlet oxygen. In polar deuterated acetonitrile, the counterion has no effect on the efficiency of photosensitization of oxygen by the dyes.

Optical properties of new indotricarbocyanine dye as a limiter of laser radiation power

We present results of experimental and theoretical studies of the optical characteristics of a new indotricarbocyanine dye that is capable of effectively limiting the power of laser radiation in the visible spectral range. The spectral-luminescent and energy characteristics of the dye molecules and their absorption spectra from the excited state with nanosecond resolution are investigated experimentally. Quantum-chemical methods are used to calculate electronic absorption spectra from the ground (S0 → Sn) and excited (S1 → Sn) states and to determine the nature of electronic states of the molecule and the rate constants of intramolecular photophysical processes. The results of the theoretical research agree with experimental data. It is shown that the investigated dye has singlet-singlet absorption at 400–600 nm. Nonlinear absorption of the dye upon excitation by radiation of the second harmonic of a Nd:YAG laser is studied by z-scanning with an open diaphragm. The ratio of dye absorption cross sections from the excited and ground states at 532 nm is determined in the framework of a three-level model. The results are compared with those for previously studied compounds.

Photodynamic laser therapy and diagnostics of tumor localization on the basis of new types of photosensitizers

Characteristics of photophysical and photochemical processes in molecules of new symmetric indotricarbocyanine dyes in solutions and biostructures are studied. Correlations between the efficiency of these processes and the specific features of the dye molecule structure, as well as the influence of the physical and chemical parameters of the medium and exciting radiation on these processes are established.

Optical molecular imaging of lymph nodes using a targeted vascular contrast agent

We develop a highly specific antibody-dye conjugate for optical imaging of peripheral lymph nodes. The contrast agent consists of the monoclonal antibody recognizing endothelial ligands for the lymphocyte homing receptor L-selectin, MECA-79, and a near-infrared (near-IR) fluorescent indotricarbocyanine dye. The targeting and biodistribution behavior of MECA-79 is studied after radio-iodination and intravenous injection into mice demonstrating specific uptake in lymph nodes and accumulation in high endothelial venules (HEV). After conjugation of MECA-79 with indotricarbocyanine dye, the fluorescence imaging properties of the MECA-79 dye conjugate are examined by intravenous injection in nude mice and laser-induced fluorescence whole-body imaging in vivo. The MECA-79 antibody-dye conjugate accumulates in peripheral lymph nodes, whereas an isotype antibody-dye conjugate does not. Specific lymph node near-IR fluorescent signals become detectable within minutes after injection, and stable imaging persists for more than 24 h. The results demonstrate that vascular targeting of endothelial expression of glyocproteins is feasible to visualize the accumulation of near-IR fluorescent MECA-79 in lymph nodes, making this technology potentially useful to characterize processes of inflammation.

Spectral-Luminescent Properties of Cationic Indotricarbocyanine Dyes in Cancerous Cells and Solutions

The spectral-luminescent properties of symmetrical indotricarbocyanine dyes with the same cation and different anions (Br−, BF4 −) in cancerous HeLa cells, an isotonic solution of NaCl, and organic solvents have been investigated. It is shown that when these dyes are present in cells in nontoxic concentrations, they are in a monomeric state, they are localized in the region with a low dielectric permeability, bonded to biological macromolecules, and do not make contact with an aqueous medium. It has been established for the first time that the molecules of the polymeric dyes are present in cells predominantly in the form of contact ion pairs, and in a dye with the Br− anion the presence of free cations or solvately separated ionic pairs is revealed. It is shown that the shift of the ion equilibrium toward contact ion pairs for the dyes in the cells (as compared to the low-polarity organic solvents) can be due to the fairly high concentration of salts in the biosystem.

Features of Emission and Absorption of Indotricarbocyanine Dyes on Excitation to Higher Electronic States

The manifestation of ion pairs in the absorption and emission of fluorescence by symmetric indotricarbocyanine dyes with the same cation and anions Br, I, and BF4 in ethanol, methylene chloride, and dichlorobenzene has been investigated. It is shown that the formation of ion pairs on passing to low-polarity solvents, along with the changes in the electronic absorption and emission spectra, manifests itself in the polarization and fluorescence excitation spectra. We were the first to establish that the presence of an equilibrium mixture of contact ion pairs and free ions in solutions has an effect on the position and probabilities of transitions not only for the first but also for higher excited singlet states of the molecules of polymethine dyes. The formation of ion pairs manifests itself more clearly when the spectral-luminescence properties of compounds in the shortwave spectral region are analyzed. It has been established that marked changes arise in the absorption, excitation, emission, and polarization fluorescence spectra, as well as in the lifetime and quantum yield of fluorescence in this spectral region when the solvent is changed.

Counter-Anion Effect on the Thermal Stability of Amorphous Solid Films of Indotricarbocyanine Dyes under Highly Humid Conditions

Counter-Anion Effect on the Thermal Stability of Amorphous Solid Films of Indotricarbocyanine Dyes under Highly Humid Conditions