Interaction Of Singlet Oxygen Research Articles

SsDNA damage dependence from singlet oxygen concentration at photodynamic interaction

Single stranded DNA damage at photodynamic treatment with Radachlorin photosensitizer was investigated. Chemical trap method was used to evaluate generation of singlet oxygen in water solution. Interaction of singlet oxygen with ssDNA resulted into decrease of the replication activity of ssDNA. DNA stopped replicating during PCR at irradiation doses greater than 15 J/cm2 and concentration of photosensitizer [PS] = 3.8 μM. The dependence of replication activity of ssDNA on generated singlet oxygen concentration was identified.

Prospects of in vivo singlet oxygen luminescence monitoring: Kinetics at different locations on living mice

BackgroundSinglet oxygen observation is considered a valuable tool to assess and optimize PDT treatment. In complex systems, such as tumors in vivo, only the direct, time-resolved singlet oxygen luminescence detection can give reliable information about generation and interaction of singlet oxygen. Up to now, evaluation of kinetics was not possible due to insufficient signal-to-noise ratio. Here we present high signal-to-noise ratio singlet oxygen luminescence kinetics obtained in mouse tumor model under PDT relevant conditions. MethodsA highly optimized system based on a custom made laser diode excitation source and a high aperture multi-furcated fiber, utilizing a photomultiplier tube with a multi photon counting device was used. ResultsLuminescence kinetics with unsurpassed signal-to-noise ratio were gained from tumor bearing nude mice in vivo upon topic application, subcutaneous injection as well as intravenous injection of different photosensitizers (chlorin e6 and dendrimer formulations of chlorin e6). Singlet oxygen kinetics in appropriate model systems are discussed to facilitate the interpretation of complex kinetics obtained from in vivo tumor tissue. ConclusionsThis is the first study addressing the complexity of singlet oxygen luminescence kinetics in tumor tissue. At present, further investigations are needed to fully explain the processes involved. Nevertheless, the high signal-to-noise ratio proves the applicability of direct time-resolved singlet oxygen luminescence detection as a prospective tool for monitoring photodynamic therapy.

Interaction of singlet oxygen with bovine serum albumin and the role of the protein nano-compartmentalization

Singlet molecular oxygen (1O2) contributes to protein damage triggering biophysical and biochemical changes that can be related with aging and oxidative stress. Serum albumins, such as bovine serum albumin (BSA), are abundant proteins in blood plasma with different biological functions. This paper presents a kinetic and spectroscopic study of the 1O2-mediated oxidation of BSA using the tris(2,2′-bipyridine)ruthenium(II) cation [Ru(bpy)3]2+ as sensitizer. BSA quenches efficiently 1O2 with a total (chemical+physical interaction) rate constant ktBSA=7.3(±0.4)×108M−1s−1, where the chemical pathway represented 37% of the interaction. This efficient quenching by BSA indicates the participation of several reactive residues. MALDI-TOF MS analysis of intact BSA confirmed that after oxidation by 1O2, the mass protein increased the equivalent of 13 oxygen atoms. Time-resolved emission spectra analysis of BSA established that Trp residues were oxidized to N′-formylkynurenine, being the solvent-accessible W134 preferentially oxidized by 1O2 as compared with the buried W213. MS confirmed oxidation of at least two Tyr residues to form dihydroxyphenylalanine, with a global reactivity towards 1O2 six-times lower than for Trp residues. Despite the lack of MS evidences, kinetic and chemical analysis also suggested that residues other than Trp and Tyr, e.g. Met, must react with 1O2. Modeling of the 3D-structure of BSA indicated that the oxidation pattern involves a random distribution of 1O2 into BSA; allowing also the interaction of 1O2 with buried residues by its diffusion from the bulk solvent through interconnected internal hydrophilic and hydrophobic grooves.

Stable Optical Oxygen Sensing Material Based on Perfluorinated Polymer and Fluorinated Platinum(II) and Palladium(II) Porphyrins

Commercially available dissolved oxygen analyzer with an optical detection method based on phosphorescence quenching was created. The sensitive element of the sensor contains a metal complex of fluorine-substituted porphyrin (platinum(II) or palladium(II) 5,10,15,20-mesotetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin) dissolved in poly(hexafluoropropylene) (PHFP) matrix. Perfluorinated polymer was applied to avoid interaction of singlet oxygen with polymer matrix. The measurement of oxygen concentration is based on the change of the lifetime of the phosphorescent state due to luminescence quenching by molecular oxygen, which is more precise than the intensity detection method. A series of test were performed to estimate metrological characteristics of the analyzer. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than electrochemical sensors previously used.

Luminescence investigation of photosensitizer distribution in skin: correlation of singlet oxygen kinetics with the microarchitecture of the epidermis

This is the first study showing that singlet oxygen kinetics of topically applied photosensitizers coincides with the microarchitecture of skin, e.g., fissures and hair follicles. The kinetics indicate a chemical interaction of singlet oxygen with the skin, which allows differentiating between residual crème, e.g., in the follicular orifice, and photosensitizer penetrated into the skin. We show the feasibility of an easy-to-use fiber optic application providing the opportunity for in situ investigation, as well as a setup with focused optics for high-resolution two-dimensional scanning of singlet oxygen luminescence kinetics in skin samples. The results show that time-resolved singlet oxygen luminescence detection in tissue is a desirable tool for medical therapy, diagnostics, and evaluation of singlet oxygen interaction with biological environments.

Luminescence spectroscopy of singlet oxygen enables monitoring of oxygen consumption in biological systems consisting of fatty acids

The interaction of singlet oxygen ((1)O2) generated in a photosensitized process with well-known reference photosensitizers Perinaphthenone (PN) and TMPyP is investigated in a model system consisting of fatty acids and the respective exogenous photosensitizer (PS) in solution by direct detection of the luminescence photons of (1)O2 at 1270 nm. Such a model system is a first approach to mimic the complex environment of (1)O2 in a biological cell which consists mainly of water, proteins, sugars and lipids. Firstly, the important issue of oxygen consumption is evaluated which has to be considered during luminescence detection of (1)O2. It is known that the luminescence signal of (1)O2 is dependent on the oxygen concentration of the environment. Cellular components such as lipids represent oxygen consumers due to peroxidation of their unsaturated double bonds. Secondly, the experimental conditions for this model system regarding oxygen consumption are optimized to estimate the rates and rate constants of the coupled system. Thirdly, the triplet decay of the PS can provide more precise information about the actual oxygen concentration close to the PS and can be used, therefore, as a more precise method to determine the oxygen concentration in more complex systems such as a biological cell. The aim is to get a better understanding of photosensitized reactions of (1)O2 with cellular components to further improve methodologies, in particular at a cellular level using luminescence spectroscopy. In conclusion, luminescence detection might be a helpful tool to monitor precisely and promptly changes in oxygen concentration in a complex environment.

New insight into singlet oxygen generation at surface modified nanocrystalline TiO2 – the effect of near-infrared irradiation

The generation of singlet oxygen in aqueous colloids of nanocrystalline TiO2 (anatase) modified by organic chelating ligands forming surface Ti(IV) complexes was studied. Detailed studies revealed a plausible and to date unappreciated influence of near-infrared irradiation on singlet oxygen generation at the surface of TiO2. To detect (1)O2, direct and indirect methods have been applied: a photon counting technique enabling time-resolved measurements of (1)O2 phosphorescence, and fluorescence measurements of a product of singlet oxygen interaction with Singlet Oxygen Sensor Green (SOSG). Both methods proved the generation of (1)O2. Nanocrystalline TiO2 modified with salicylic acid appeared to be the most efficient photosensitizer among the tested materials. The measured quantum yield reached the value of 0.012 upon irradiation at 355 nm, while unmodified TiO2 colloids appeared to be substantially less efficient generators of singlet oxygen with the corresponding quantum yield of ca. 0.003. A photocatalytic degradation of 4-chlorophenol, proceeding through oxidation by OH˙, was also monitored. The influence of irradiation conditions (UV, vis, NIR or any combination of these spectral ranges) on the generation of both singlet oxygen and hydroxyl radicals has been tested and discussed. Simultaneous irradiation with visible and NIR light did not accelerate OH˙ formation; however, for TiO2 modified with catechol it influenced (1)O2 generation. Singlet oxygen is presumably formed according to Nosaka's mechanism comprising O2˙(-) oxidation with a strong oxidant (hole, an oxidized ligand); however, the energy transfer from NIR-excited titanium(iii) centers (trapped electrons) plays also a plausible role.

Time-resolved singlet oxygen luminescence detection under photodynamic therapy relevant conditions: comparison ofex vivoapplication of two photosensitizer formulations

Singlet oxygen plays a crucial role in photo-dermatology and photodynamic therapy (PDT) of cancer. Its direct observation by measuring the phosphorescence at 1270 nm, however, is still challenging due to the very low emission probability. It is especially challenging for the time-resolved detection of singlet oxygen kinetics in vivo which is of special interest for biomedical applications. Photosensitized generation of singlet oxygen, in pig ear skin as model for human skin, is investigated here. Two photosensitizers (PS) were topically applied to the pig ear skin and examined in a comparative study, which include the amphiphilic pheophorbide-a and the highly hydrophobic perfluoroalkylated zinc phthalocyanine (F64PcZn). Fluorescence microscopy indicates the exclusive accumulation of pheophorbide-a in the stratum corneum, while F64PcZn can also accumulate in deeper layers of the epidermis of the pig ear skin. The kinetics obtained with phosphorescence measurements show the singlet oxygen interaction with the PS microenvironment. Different generation sites of singlet oxygen correlate with the luminescence kinetics. The results show that singlet oxygen luminescence detection can be used as a diagnostic tool, not only for research, but also during treatment. The detection methodology is suitable for the monitoring of chemical quenchers’ oxidation as well as saturation at singlet oxygen concentration levels relevant to PDT treatment protocols.

New insights to primary photodynamic effects – Singlet oxygen kinetics in living cells

The kinetics of chemical singlet oxygen quencher consumption inside living cells during low dose illumination was revealed via time resolved singlet oxygen luminescence detection. Deviations of the measured data from the common theoretical model for 1O 2 kinetics forced the authors to consider a one-dimensional diffusion model for description of the kinetics of singlet oxygen generated by membrane localized photosensitizers. Our observations reconcile seemingly contradictory reports presenting different values for the efficiency of singlet oxygen interaction with cells.

Oxyfunctionalization of Alkenes by Dye‐Sensitized Intrazeolite Photooxygenation

AbstractFor Abstract see ChemInform Abstract in Full Text.

Oxyfunctionalization of Alkenes by Dye-Sensitized Intrazeolite Photooxygenation

This review focuses on the recent achievements towards the selective formation of allylic hydroperoxides by the reaction of singlet molecular oxygen ( 1 O 2) with alkenes adsorbed in the cavities of zeolite Na-Y. The product distribution by zeolite confinement is often dramatically different compared to the photooxygenation reaction in a homogeneous medium. Cation - π interactions and cation - singlet oxygen interactions, in the rate-limiting transition states, are most likely responsible for the changes in product selectivity within Na-Y. STRUCTURAL FEATURES OF FAUJASITES Zeolites are crystalline aluminosilicates whose primary structure is formed by SiO4 4- and AlO4 5- tetrahedra sharing the edges (1). Their tertiary structure forms strictly uniform channels and cavities of molecular dimensions that are repeated along the zeolite lattice. Due to the lower valence of the aluminum relative to silicon, the excess negative charge (one per Al atom) is balanced by alkali metal cations, mainly Na + . The cations are placed in the interior of cavities and can be easily exchanged. The cation-exchange process leads to new type of materials having interesting properties (2), and it is expected in the near future that the metal- supported zeolites will find significant applications in applied chemistry.

Interaction of singlet oxygen and superoxide radical anion with guanine and formation of its mutagenic modification 8‐oxoguanine

AbstractFormation of 8‐oxoguanine (8OG) from guanine in biological systems is known to cause lethal mutation and cancer. It has been suggested earlier, on the basis of experimental studies, that the oxygen molecule in its lowest singlet excited state (1O2) plays an important role in the formation of 8OG. In order to understand the possible mechanisms in this context, B3LYP/6‐31+G* and MP2/6‐31+G* calculations were carried out on the structures and stabilities of different molecules and complexes involved in the formation of 8OG. All the molecules, complexes, and transition states studied in the present report were solvated in aqueous media. Guanine has been found to make a strong complex with 1O2 with the latter species located above the imidazole ring plane, and the complex of guanine with 3O2 is much weaker than that with 1O2. Transition state calculations were carried out to study formation of 7,8‐dihydro,8‐hydroxyguanine (8OHG) and 2‐oxo‐imidazole. It has been shown that 8OG can be formed in two different ways: (i) due to interaction of the radical cation of guanine with O where 8OHG complexed with 1O2 would occur as an intermediate, and (ii) due to interaction of guanine with 1O2 leading to the formation of guanine hydroperoxide that would react with a water molecule in the presence of two 1O2 molecules serving as a source of energy to overcome the barrier. It is shown that because the interaction strengths of 3O2 and 1O2 with other molecules, e.g., guanine, are very different, a crossing of their potential energy surfaces takes place in both gas phase and aqueous media, as a result of which the lifetime of 1O2 is strongly decreased. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

Dye-sensitized intrazeolite photooxygenation of 4-substituted cyclohexenes. Remote substituent effects in regioselectivity and diastereoselectivity

The product distribution in the dye-sensitized photooxygenation of α-terpinyl acetate and terpinen-4-ol is quite similar in solution, however, by zeolite Y confinement, is substantially influenced by the position of the remote polar substituents relative to the reacting double bond. The intrazeolite results were rationalized in terms of Na+-substrate and Na+-singlet oxygen interactions.

The Influence of Heteroatoms on the Extent of Double Bond Pyramidalization

AbstractThe origin of double bond pyramidalization in the series of norbornene and norbornadiene derivatives and the effect of heteroatoms on the magnitude of the double bond bending are reported. For this purpose, equilibrium geometries, vibrational frequencies, and NBO second‐order perturbation energies were calculated by use of B3LYP/6‐31G** level wave functions. The optimized geometric parameters calculated for norbornadiene are in good agreement with the available experimental results. NBO second‐order perturbation analysis has been used to evaluate the effect of hyperconjugative interactions on double bond pyramidalization. In the second part of this study, the interaction of singlet oxygen with 4,5‐dioxatetracyclo[6.6.1.02,7.09,14]pentadeca‐2(7),9,11,13‐tetraene (15) and 4,5,15‐trioxatetracyclo[6.6.1.02,7.09,14]pentadeca‐2(7),9,11,13‐tetraene (16) has been studied at the B3LYP/6‐31G** level. In the case of addition of singlet oxygen to 15, 4,5,16‐trioxapentacyclo[6.6.1.12,7.02,7.09,14]hexadeca‐9,11,13‐triene (17) is produced. It was found that the reaction of singlet oxygen addition to the double bond in 16 does not occur. The degree of pyramidalization in this molecule is similar to the analog 12 {4,5,11‐trioxatricyclo[6.2.1.02,7]undeca‐2(7),9‐diene}, in which singlet oxygen addition takes place. The reasons of the lack of chemical reactivity with singlet oxygen in 16 are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Effect of vanillin on methylene blue plus light-induced single-strand breaks in plasmid pBR322 DNA

The ability of vanillin (4-hydroxy-3-methoxybenzaldehyde), a naturally occurring food flavouring agent, in inhibiting photosensitization-induced single-strand breaks (ssbs) in plasmid pBR322 DNA has been examined in an in vitro system, independent of DNA repair/replication processes. Photosensitization of DNA with methylene blue, visible light and oxygen, induced ssbs resulting in the production of open circular form (OC form) in a concentration-dependent manner. The yield of OC form induced by photosensitization was increased several-fold by deuteration of the buffer and was found to be inhibited by sodium azide, a scavenger of singlet oxygen (1O2). Vanillin, per se, did not induce but inhibited photosensitization-induced ssbs in plasmid DNA, at millimolar concentrations. The inhibitory effect of vanillin was both concentration- and time-dependent. On a molar basis, vanillin was, however, less effective than trolox, a water-soluble analogue of α-tocopherol. Photosensitization by methylene blue system generates singlet oxygen, as one of the major components of ROS. Therefore, interaction of singlet oxygen with vanillin was investigated. The rate constant of vanillin with 1O2 was estimated to be 5.93×107M−1s−1 and that of sodium azide as 2.7×108M−1s−1. The present investigations show that vanillin can protect against photosensitization-induced ssbs in the plasmid pBR322 DNA, and this effect may partly be due to its ability to scavenge 1O2.

2] Photosensitized production of singlet oxygen

Photosensitization is a simple and controllable method for the generation of singlet oxygen in solution and in cells. Methods are described for determining the yield of singlet oxygen in solution, for measurement of the rate of reaction between singlet oxygen and a substrate, and for comparing the effectiveness of singlet oxygen generated by different photosensitizers in cells. These quantitative measurements can lead to better understanding of the interaction of singlet oxygen with biomolecules.

Interaction of singlet oxygen with biomolecules, 2.1O2 quenching by glycirrhizic acid derivatives

Overall constants for the singlet oxygen quenching rate by β-glycirrhizic acid derivatives (ether, amide, isocyanate, isothiocyanate, urethane, glycopeptide) are determined. Introduction of substituents in the β-glycirrhizic acid molecule decreases the rate constant by 1–3 orders of magnitude.

Interaction of Singlet Oxygen with Peroxy and Acylperoxy Radicals

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionInteraction of Singlet Oxygen with Peroxy and Acylperoxy RadicalsA. P. Darmanyan, C. S. Foote, and P. JardonCite this: J. Phys. Chem. A 1997, 101, 44, 8366Publication Date (Web):October 30, 1997Publication History Published online30 October 1997Published inissue 1 October 1997https://doi.org/10.1021/jp972749aCopyright © 1997 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views202Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (13 KB) Get e-Alerts Get e-Alerts

Photochemical transformation of polychlorinated phenols

To increase our understanding of the photocatalytic effects in the transformation of chlorinated organic compounds, the detailed mechanism of the direct photolysis of polychlorinated phenols has been established under aerobic and anaerobic conditions. The quantum yield of photolysis of 2,4,5-trichlorophenol (2,4,5-TCP) has been determined at different wavelenghts and pH values. It has been shown that direct photolysis of polychlorinated phenols is accompanied by chloride ion detachment from different positions of the benzene ring with the formation of 2,5-dichlorohydroquinone and dichlorocyclopentadiene derivatives in the case of 2,4,5-TCP, as well as polychlorinated dibenzodioxins (PCDD) and dibenzofurans (PCDF). Based on the 2,4,5-TCP direct photolysis products, it has been concluded that chlorophenol free radicals are formed as a result of CCl cleavage, which probably act as the origin of highly chlorinated PCDD and PCDF. To utilize visible light in the photocatalytic destruction of organic pllutants, we investigated the kinetics of transformation of polychlorinated phenols in systems involving singlet oxygen formation (dye-sensitized reactions with Rose Bengal, Methylene Blue and Eosin). It has been shown that superoxide radical is not reactive towards 2,4,5-TCP, whereas singlet oxygen results in the destructive oxidation of polychlorinated phenols without formation of PCDD and PCDF among the reaction products. The detailed mechanism of the interaction of singlet oxygen with 2,4,5-TCP has been investigated. It has been concluded that the initial trichlorophenol is dechlorinated and singlet oxygen interaction with 2,4,5-TCP proceeds via a mechanism with the formation of hydrogen peroxide without intermediate superoxide radicals.

Interaction of singlet oxygen with peroxy and acylperoxy radicals

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInteraction of singlet oxygen with peroxy and acylperoxy radicalsAlexander P. Darmanyan, Christopher S. Foote, and Pierre JardonCite this: J. Phys. Chem. 1995, 99, 31, 11854–11859Publication Date (Print):August 1, 1995Publication History Published online1 May 2002Published inissue 1 August 1995https://doi.org/10.1021/j100031a011RIGHTS & PERMISSIONSArticle Views134Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (659 KB) Get e-Alerts