Naphthalene Endoperoxide Heterodimer Designed for Sustained Singlet Oxygen Release
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ABSTRACT:
SUBMITTER: Liu Z
PROVIDER: S-EPMC8515818 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The usefulness of a fiber optic technique for generating singlet oxygen and releasing the pheophorbide photosensitizer has been increased by the fluorination of the porous Vycor glass tip. Singlet oxygen emerges through the fiber tip with 669-nm light and oxygen, releasing the sensitizer molecules upon a [2 + 2] addition of singlet oxygen with the ethene spacer and scission of a dioxetane intermediate. Switching from a nonfluorinated to a fluorinated glass tip led to a clear reduction of the adsorbtive affinity of the departing sensitizer with improved release into homogeneous toluene solution and bovine tissue, but no difference was found in water since the sensitizer was insoluble. High surface coverage of the nonafluorohexylsilane enhanced the cleavage efficiency by 15% at the ethene site. The fluorosilane groups also caused crowding and seemed to reduce access of (1)O(2) to the ethene site, which attenuated the total quenching rate constant k(T), although there was less wasted (1)O(2) (from surface physical quenching) at the fluorosilane-coated than the native SiOH silica. The observations support a quenching mechanism that the replacement of the SiOH groups for the fluorosilane C-H and C-F groups enhanced the (1)O(2) lifetime at the fiber tip interface due to less efficient electronic-to-vibronic energy transfer.
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Project description:Singlet oxygen (1O2), as an important active reagent, has found wide applications in photodynamic therapy (PDT), synthetic chemistry, and materials science. Organic conjugated aromatics serving as hosts to capture and release singlet oxygen have been systematically investigated over the last decades. Herein, we present a [6 + 6] organoplatinum(II) metallacycle by using ∼180° dipyridylanthracene donor and ∼120° Pt(II) acceptor as the building blocks, which enables the capture and release of singlet oxygen with relatively high photooxygenation and thermolysis rate constants. The photooxygenation of the metallacycle to the corresponding endoperoxide was performed by sensitized irradiation, and the resulting endoperoxide is stable at room temperature and can be stored under ambient condition over months. Upon simple heating of the neat endoperoxide under inert atmosphere at 120 °C for 4 h, the resulting endoperoxide can be reconverted to the corresponding parent form and singlet oxygen. The photooxygenation and thermolysis products were characterized by NMR spectroscopy and electrospray ionization time-of-flight mass spectrometric analysis. Density functional theory calculations were conducted in order to reveal the frontier molecular orbital interactions and reactivity. This work provides a new material platform for singlet oxygen related promising applications.
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Project description:Formation of singlet oxygen (1O2) was reported to accompany light stress in plants, contributing to cell signaling or oxidative damage. So far, Singlet Oxygen Sensor Green (SOSG) has been the only commercialized fluorescent probe for 1O2 imaging though it suffers from several limitations (unequal penetration and photosensitization) that need to be carefully considered to avoid misinterpretation of the analysed data. Herein, we present results of a comprehensive study focused on the appropriateness of SOSG for 1O2 imaging in three model photosynthetic organisms, unicellular cyanobacteria Synechocystis sp. PCC 6803, unicellular green alga Chlamydomonas reinhardtii and higher plant Arabidopsis thaliana. Penetration of SOSG differs in both unicellular organisms; while it is rather convenient for Chlamydomonas it is restricted by the presence of mucoid sheath of Synechocystis, which penetrability might be improved by mild heating. In Arabidopsis, SOSG penetration is limited due to tissue complexity which can be increased by pressure infiltration using a shut syringe. Photosensitization of SOSG and SOSG endoperoxide formed by its interaction with 1O2 might be prevented by illumination of samples by a red light. When measured under controlled conditions given above, SOSG might serve as specific probe for detection of intracellular 1O2 formation in photosynthetic organisms.
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Project description:To identify components involved in the signal transduction and activation of the singlet oxygen-mediated response, a mutant selection was performed. This led to the isolation of the singlet oxygen resistant 1 (sor1) mutant, which is more tolerant to singlet oxygen-producing chemicals and shows a constitutively higher expression of GPXH and GSTS1. Map-based cloning revealed that the SOR1 gene encodes a novel bZIP transcription factor, which seems to control its own expression as well as that of a large number of oxidative stress response and detoxification genes. In the promoter region of many of these genes a highly conserved 8-bp palindromic sequence element was found to be enriched. This element was shown to be essential for GSTS1 overexpression in sor1 and for induction by increased levels of lipophilic reactive electrophile species (RES) suggesting that it functions as an electrophile response element (ERE). RES can be formed after singlet oxygen-induced lipid peroxidation, indicating that a RES-stimulated and SOR1-mediated response of detoxification genes is part of the singlet oxygen-induced acclimation process in C. reinhardtii.
2012-04-03 | GSE33548 | GEO
Project description:The use of polyaromatic hydrocarbons to capture and release singlet oxygen is of considerable importance in materials chemistry, synthesis, and photodynamic therapy. Here we studied the ability of a series of tethered twistacenes, possessing different degrees of backbone twist, to capture and release singlet oxygen via the reversible Diels-Alder reaction. When the twistacene acts as both a sensitizer and a diene, the photo-oxidation rate depends on the extinction coefficient of the irradiation wavelength. However, when the twistacenes function solely as a diene, the rate of photo-oxidation increases with increasing twist. The rate of the reverse reaction, the singlet oxygen release, also increases with increasing twist. The calculated transition state energy decreases with increasing twist, which can explain the observed trend. The presence of the tether significantly increases the reversibility of the reaction, which can proceed in repeated forward and reverse cycles in very high yield under mild conditions, as required for molecular switches.
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Project description:Highly-controllable release consisting of preventing unnecessary drug leakage at physiologically normal tissues and triggering sufficient drug release at tumor sites is the main aim of nanoparticle-based tumor therapy. Developing drug-conjugation strategies with covalent bonds in response to a characteristic stimulus, such as reactive oxygen species (ROS) generated by photodynamic therapy (PDT) has attracted much attention. ROS can not only cause cytotoxicity, but also trigger the cleavage of ROS-responsive linkers. Therefore, it is feasible to design a new model of controlled drug release via the breakage of ROS-responsive linkers and degradation of nanoparticles. The self-supply of the stimulus and highly-controllable drug release can be achieved by encapsulation of photosensitizer (PS) and chemotherapeutic drugs simultaneously without any support of tumor endogenous stimuli. Therefore, we used thioketal (TK) linkers as the responsive linkers due to their reaction with singlet oxygen (1O2, SO), a type of ROS. They were conjugated to the side groups of polyphosphoesters (PPE) via click chemistry to acquire the core cross-linked SO-responsive PPE nanoparticles poly(thioketal phosphoesters) (TK-PPE). TK-PPE coated with the photosensitizer chlorin e6 (Ce6) and chemotherapeutic drug doxorubicin (DOX) simultaneously were prepared and named as TK-PPECe6&DOX. TK-PPECe6&DOX kept stable due to the high stability of the TK-linkers in the normal physiological environment. With self-production of SO as the stimulating factor from the encapsulated Ce6, highly-controlled drug release was achieved. After incubation of tumor cells, 660 nm laser irradiation induced SO generation, resulting in the cleavage of TK-linkers and boosted-release of DOX. Highly-controllable drug release of TK-PPECe6&DOX through self-production of stimulus increased antitumor efficacy, offering a promising avenue for clinical on-demand chemotherapy.
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Project description:Intratumoral hypoxia extremely limits the clinic applications of photodynamic therapy (PDT). Endoperoxides allow thermally releasing singlet oxygen (1O2) in a defined quantity and offer promising opportunities for oxygen-independent PDT treatment of hypoxic tumors. However, previous composite systems by combining endoperoxides with photothermal reagents may result in unpredicted side effects and potential harmful impacts during therapy in vivo. Herein, we de novo design an all-in-one polymer carrier, which can photothermally release 1O2. The strategy has been demonstrated to effectively enhance the production of 1O2 and realize the photodamage in vitro, especially in hypoxic environment. Additionally, the polymer carrier accumulates into tumor after intravenous injection via the enhanced permeation and retention effects and accelerates the oxygen-independent generation of 1O2 in tumors. The oxidative damage results in good inhibitory effect on tumor growth. Realization of the strategy in vivo paves a new way to construct photothermal-triggered oxygen-independent therapeutic platform for clinical applications.
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Project description:We used the flu mutant of Arabidopsis to detail gene expression in response to singlet oxygen. The conditional flu mutant of Arabidopsis accumulates excess protochlorophyllide in the dark within chloroplast membranes that upon illumination acts as a photosensitizer and generates singlet oxygen. Immediately after the release of singlet oxygen mature flu plants stop growing, whereas seedlings bleach and die. Within the first 30 min after the release of singlet oxygen rapid changes in nuclear gene expression occur. Distinct sets of genes were activated that were different from those induced by other reactive oxygen species, superoxide or hydrogen peroxide. Keywords: Time course
2008-03-18 | GSE10876 | GEO
Project description:Acclimation of Chlamydomonas reinhardtii cells to low levels of singlet oxygen, produced either by photoreactive chemicals or high light treatment, induces a specific genetic response that strongly increases the tolerance of the algae to subsequent exposure to normally lethal singlet oxygen-producing conditions. The genetic response includes the increased expression of various oxidative stress response and detoxification genes, like the glutathione peroxidase homologous gene GPXH/GPX5 and the ?-class glutathione-S-transferase gene GSTS1. To identify components involved in the signal transduction and activation of the singlet oxygen-mediated response, a mutant selection was performed. This selection led to the isolation of the singlet oxygen resistant 1 (sor1) mutant, which is more tolerant to singlet oxygen-producing chemicals and shows a constitutively higher expression of GPXH and GSTS1. Map-based cloning revealed that the SOR1 gene encodes a basic leucine zipper transcription factor, which controls its own expression and the expression of a large number of oxidative stress response and detoxification genes. In the promoter region of many of these genes, a highly conserved 8-bp palindromic sequence element was found to be enriched. This element was essential for GSTS1 induction by increased levels of lipophilic reactive electrophile species (RES), suggesting that it functions as an electrophile response element (ERE). Furthermore, GSTS1 overexpression in sor1 requires the ERE, although it is unknown whether it occurs through direct binding of SOR1 to the ERE. RES can be formed after singlet oxygen-induced lipid peroxidation, indicating that RES-stimulated and SOR1-mediated responses of detoxification genes are part of the singlet oxygen-induced acclimation process in C. reinhardtii.
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