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Sample records for boronated porphyrin photosensitizer

  1. The coordination chemistry of boron porphyrin complexes B2OX2 ...

    Indian Academy of Sciences (India)

    Unknown

    therapeutic method that utilizes porphyrin deriva- tives localized in tumors, as in situ photosensitizers for the production of singlet oxygen on irradiation with red light.2 Candidate porphyrin derivatives that contain boron for boron neutron capture therapy (BNCT) ... in small animal glioma models.4,5 BNCT is a two-step.

  2. Synthesis, spectroscopy and photosensitizing properties of hydroxynitrophenyl porphyrins

    Energy Technology Data Exchange (ETDEWEB)

    Maestrin, Ana Paula J.; Tedesco, Antonio Claudio; Neri, Claudio R.; Gandini, Maria Elisa F.; Serra, Osvaldo A.; Iamamoto, Yassuko [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Inst. de Quimica]. E-mail: osaserra@usp.br

    2004-10-01

    The hydroxynitrophenyl porphyrins, 5,10,15,20-tetrakis(2-hydroxy-5-nitrophenyl)porphyrin and 5-mono(carboxyphenyl)-10,15,20-tris(2-hydroxy-5-nitrophenyl)porphyrin described in this work were prepared through Adler's method. These compounds were characterized by {sup 1}H NMR and light absorption and emission spectroscopy in the visible region. In order to demonstrate the involvement of {sup 1}O{sub 2} production, the uric (UA) acid test was carried out, which considers the decrease in the absorbance of UA at 293 nm following laser light irradiation of a solution containing UA and a photosensitizer. The results obtained demonstrate that these hydroxynitrophenyl porphyrins can be considered as promising photosensitizers in PDT. (author)

  3. Tumor localization of boronated porphyrins in an intracerebral model of glioma

    International Nuclear Information System (INIS)

    Hill, J.S.; Kaye, A.H.; Gonzales, M.F.; Stylli, S.S.; Nakamura, Y.; Kahl, S.B.; Vardaxis, N.J.; Johnson, C.I.

    1992-01-01

    Treatment of the most common cerebral tumor, cerebral glioma, is unsatisfactory as the tumor recurs due to inadequate local control. Photodynamic therapy (PDT) and Boron Neutron Capture Therapy (BNCT) offer some promise as adjuvant treatments for cerebral glioma. Several clinical trials have been reported utilizing PDT and BNCT to treat the high grade glioma, glioblastoma multiforme. The authors have investigated the pharmacokinetic tissue distribution of the photosensitizer Haematoporphyrin derivative (HpD), the nido carboranyl porphyrin, boron tetraphenyl porphine (BTPP) and the closo carboranyl monomeric protoporphyrin (BOPP) in CBA mice bearing the intracerebral C6 glioma xenograft

  4. Effect of DNA microenvironment on photosensitized reaction of watersoluble cationic porphyrins.

    Science.gov (United States)

    Hirakawa, Kazutaka; Nakajima, Shuku

    2014-01-01

    Endogenous and exogenous photosensitizers induce DNA damage, leading to carcinogenesis. Further, DNA is an important target biomacromolecule of photodynamic therapy (PDT) for cancer. Since the solar-induced DNA damage and PDT reaction occur in a complex biological environment, the interaction between biomolecule and photosensitizer is important. In this study, we examined the effect of a DNA microenvironment on the photosensitized reaction by watersoluble porphyrin derivatives, tetrakis(N-methyl-p-pyridinio)porphyrin (H(2)TMPyP) and its zinc complex (ZnTMPyP). In the presence of a sufficient concentration of DNA, H(2)TMPyP mainly intercalates to calf thymus DNA, whereas ZnTMPyP binds into a DNA groove. An electrostatic interaction with DNA raises the redox potential of the binding porphyrins. This effect suppressed the photoinduced electron transfer from an electron donor to the DNA-binding porphyrins, whereas the electron transfer from the porphyrins to the electron acceptor was enhanced. In the case of hydrophobic electron acceptors, static complexes with porphyrins were formed, making rapid electron transfer possible. Since the interaction with DNA cleaved this complex, the electron transfer rate was decreased in the presence of DNA. The microenvironment of a DNA strand may assist or inhibit its oxidative damage by photoinduced electron transfer through an electrostatic interaction with binding photosensitizers and the steric effect.

  5. New approaches to novel boronated porphyrins for neutron capture therapy

    International Nuclear Information System (INIS)

    Kahl, S.B.

    1986-01-01

    The use of boon compounds in the treatment of human cancer is based on the unique ability of nonradioactive 10 B nuclei to absorb thermal neutrons. The prompt nuclear reactions, which occur in neutron absorption, deliver a dose of nearly 2.8 MeV only in the vicinity of boron-containing cells, since the nuclear garments produced (alpha particles and recoil lithium atoms) travel only 10 to 15 μm. The practical, clinical use of this technique to date has been limited by the authors inability to target boron-containing compounds specifically to tumor cells in amounts sufficient for therapy and in a chemical form that has an acceptable level of toxicity. Porphyrins are one important and large class of compounds that are known to accumulate in practically all tumor systems yet examined. Such site-specific accumulation is not known to be based on any currently identifiable selective transport mechanism and yet is observed for both natural and synthetic porphyrins. Tetraphenylporphine sulfonate (TPPS) has been shown by Fairchild et al. to be an ideal model compound for assessing porphyrin uptake, and suitably boronated tetraphenyl porphine might be expected to behave similarly. This report describes the synthesis, properties, and preliminary biodistribution of such compounds

  6. Optimizing Zn porphyrin-based photosensitizers for efficient antibacterial photodynamic therapy.

    Science.gov (United States)

    Alenezi, Khazna; Tovmasyan, Artak; Batinic-Haberle, Ines; Benov, Ludmil T

    2017-03-01

    Efficient photodynamic inactivation of microbes requires highly efficient photosensitizers which kill microbial cells, but spare host tissues. One way to achieve such selectivity is to use photosensitizers that are rapidly taken up by microbes and, when applied at low concentrations, efficiently kill them after a short illumination. Design of such photosensitizers requires insight into molecular properties which are critical for antimicrobial photo-efficiency. This study explores the contribution of molecular shape and exposure of charges, to the antimicrobial activity of tetra-cationic Zn porphyrin-based photosensitizers. Two isomers, ortho (2) and meta (3) hexyl and octyl Zn(II) meso-tetrakis(N-alkylpyridinium-2(3)-yl)porphyrins [ZnTnHex-2(3)-PyP and ZnTnOct-2(3)-PyP] were compared for uptake and photo-efficiency against a Gram-negative bacterium, Escherichia coli. The highest photo-efficiency was displayed by the meta hexyl derivative. At concentration as low as 1.0μM and during only 5min of preincubation with the cells, ZnTnHex-3-PyP decreased viable cell number by about 6log 10 after only 5min of illumination. Since bacterial suspensions were thoroughly washed after preincubation with photosensitizers, this effect can be attributed only to photosensitizer taken up or bound to E. coli. Irrespective of its highest uptake by the cells, the octyl meta isomer, ZnTnOct-3-PyP, did not show higher antibacterial activity than the shorter-chain hexyl derivative, ZnTnHex-3-PyP. Efficiency and eventually selectivity of antimicrobial photosensitizers can be improved by optimizing the shape of the molecule and the position of electric charges. Increasing lipophilicity and cellular uptake per se, does not necessarily materialize in high antimicrobial efficiency of the photosensitizer. Copyright © 2016. Published by Elsevier B.V.

  7. In vitro and in vivo analysis of boronated porphyrins

    International Nuclear Information System (INIS)

    Edwards, Benjamin; Matthews, Kristin; Hou, Yongjin; Vicente, M.G.H.; Autry-Conwell, Susan; James, Boggan

    2000-01-01

    New series of meso-phenylporphyrins linked through carbon-carbon bonds to nido-carboranyl groups, and containing 26-31% boron by weight, have been reported. Dark toxicity, photo-toxicity, and measurements of uptake and efflux were performed using mouse, rat, and human malignant cell lines. Drug uptake and retention by log phase cells are shown by spectrophotometry (porphyrins) and ICP-MS (boron) of cellular extracts to be concentration and time dependent, and to be influenced by plasma lipoproteins. Plasma pharmacokinetics and tissues biodistribution were studied in adult male Fisher 344 rats with bilateral subcutaneous 9L tumors injected (2.2 ml, 2 mM i.v.) with carboranyl porphyrin solutions. Whole blood, brain, liver, spleen, skin and tumors were collected at 2, 8, 18, 24 and 48 hours post-injection. Blood cells were separated from plasma and stored frozen with the other tissues. Tissue boron content was determined quantitatively by ICP-MS analysis following microwave digestion of carefully weighed samples. (author)

  8. Trifluoromethyl Boron Dipyrromethene Derivatives as Potential Photosensitizers for Photodynamic Therapy

    Directory of Open Access Journals (Sweden)

    Jian-Yong Liu

    2018-02-01

    Full Text Available In this study, two novel boron dipyrromethene-based photosensitizers (BDP3 and BDP6 substituted with three or six trifluoromethyl groups have been synthesized and characterized with various spectroscopic methods, and their photo-physical, photo-chemical, and photo-biological properties have also been explored. The two photosensitizers are highly soluble and remain nonaggregated in N,N-dimethylformamide as shown by the intense and sharp Q-band absorption. Under red light irradiation (λ = 660 nm, 1.5 J/cm2, both photosensitizers show high and comparable cytotoxicity towards HepG2 human hepatocarcinoma and HeLa human cervical carcinoma cells with IC50 values of 0.42–0.49 μM. The high photocytotoxicity of BDP3 and BDP6 can be due to their high cellular uptake and low aggregation tendency in biological media, which result in a high efficiency to generate reactive oxygen species inside the cells. Confocal laser fluorescence microscopic studies indicate that they have superior selective affinities to the mitochondria and lysosomes of HepG2 and HeLa cells. The results show that these two trifluoromethyl boron dipyrromethene derivatives are potential anticancer agents for photodynamic therapy.

  9. Recombination and photosensitivity centres in boron nitride irradiated with ions

    International Nuclear Information System (INIS)

    Kabyshev, A.; Konusov, F.; Lopatin, V.

    2001-01-01

    The physical-chemical processes, taking place during the irradiation of dielectrics with ions distort the electron structure of the compounds and generate additional localise state in the forbidden zone (FZ). Consequently, the semiconductor layer with the specific surface density of σ ≥ 10 -10 S/ forms on the surface of the dielectric. In addition to his, the high concentration of the radiation-induced defects changes the optical and photoelectric properties of the materials and also the energy characteristics. Analysis of the photoelectric properties indicates that the recombination processes take part in electric transport. These processes restricted the increase of the photosensitivity and changing the kinetics of relaxation of photo conductivity (σ hv ). The practical application of the boron nitride (BN) the in the thermonuclear systems (for example, Ref. 7), stimulates research into the reasons for the deceleration of its properties under the effect of radiation of various types. The conductivity of non-irradiated boron nitride is of the electron-hole nature with a large fraction of the activation component in exchange of the charge carriers between the levels of the defects and the forbidden zones. On the basis of the correlation of the energy and kinetic parameters of luminescence and , the authors of Ref. 8 constructed a model of electron transfers accompanying the electric transport of the boron nitride. In addition to ion-thermal modification, the conductivity of boron nitride is also of the electron-hole nature and is accompanied by luminescence. Examination of the characteristics of luminescence may be useful for obtaining more information on the transport mechanism. In this work, in order to clarify the main parameters of the forbidden band, detailed investigations were carried out into the spectrum of the electronic states of radiation defects which determine the photoelectric and luminescence properties of the modified boron nitride. The

  10. Polystyrene nanofiber materials modified with an externally bound porphyrin photosensitizer

    Czech Academy of Sciences Publication Activity Database

    Henke, P.; Lang, Kamil; Kubát, Pavel; Sýkora, Jan; Šlouf, Miroslav; Mosinger, Jiří

    2013-01-01

    Roč. 5, č. 9 (2013), s. 3776-3783 ISSN 1944-8244 R&D Projects: GA ČR GAP208/10/1678; GA ČR GBP208/12/G016; GA ČR GA13-12496S Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:61389013 Keywords : nanofiber * porphyrin * singlet oxygen * adsorption * photooxidation * antibacterial Subject RIV: CA - Inorganic Chemistry; CD - Macromolecular Chemistry (UMCH-V); CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 5.900, year: 2013

  11. Boronated porphyrins in NCT: Results with a new potent tumor localizer

    International Nuclear Information System (INIS)

    Kahl, S.B.; Koo, M.S.; Laster, B.H.; Fairchild, R.G.

    1988-01-01

    Several chemical methods are available for the solubilization of boronated porphyrins. We have previously reported the tumor localization of nido carboranyl porphyrins in which the icosahedral carborane cages have been opened to give B 9 C 2 anions. One of these species has shown tumor boron levels of nearly 50 μg B/g when delivered by week-long subcutaneous infusions. We report here recent in vivo experiments with a new, highly water-soluble porphyrin based on the hematoporphyrin-type of compound in which aqueous solubility is achieved using the two propionic acid side chains of the ''natural'' porphyrin frame. 7 refs

  12. Hybrid systems based on gold nanostructures and porphyrins as promising photosensitizers for photodynamic therapy.

    Science.gov (United States)

    Ferreira, Daniele C; Monteiro, Camila S; Chaves, Claudilene R; Sáfar, Gustavo A M; Moreira, Roberto L; Pinheiro, Maurício V B; Martins, Dayse C S; Ladeira, Luiz Orlando; Krambrock, Klaus

    2017-02-01

    Gold nanostructures of two different shapes (spheres and rods) were synthesized to form a colloidal hybrid system with 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin tosylate salt (H 2 TM4PyP(OTs) 4 ) (POR) for applications in photodynamic therapy (PDT) using light in the visible spectral range. Electron paramagnetic resonance (EPR) experiments in combination with spin trapping were used for the detection of reactive oxygen species (ROS) and evaluation of the efficiency of these novel hybrid systems as photosensitizers. It is shown that the hybrid system consisting of gold nanorods (AuNR) and porphyrin (POR) is by far more efficient than its isolated components. This enhanced efficiency is explained by a synergetic effect between the AuNR and the porphyrin, wherein a rapid energy transfer from the former to the latter produces a large amount of singlet oxygen followed by its conversion into hydroxyl radicals. The mechanism was investigated using different spin traps and different ROS inhibitors. On the other hand, spherical gold nanoparticles (AuNP) do not show this synergetic effect. The synergetic effect for gold nanorods/POR hybrid is attributed to a larger field enhancement close to the gold nanorod surface in addition to the electrostatic attraction between the components of the hybrid system. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Effect of zinc insertion and hydrophobicity on the membrane interactions and PDT activity of porphyrin photosensitizers.

    Science.gov (United States)

    Pavani, Christiane; Uchoa, Adjaci F; Oliveira, Carla S; Iamamoto, Yassuko; Baptista, Maurício S

    2009-02-01

    A series of photosensitizers (PS), which are meso-substituted tetra-cationic porphyrins, was synthesized in order to study the role of amphiphilicity and zinc insertion in photodynamic therapy (PDT) efficacy. Several properties of the PS were evaluated and compared within the series including photophysical properties (absorption spectra, fluorescence quantum yield Phif, and singlet oxygen quantum yield PhiDelta), uptake by vesicles, mitochondria and HeLa cells, dark and phototoxicity in HeLa cells. The photophysical properties of all compounds are quite similar (Phifporphyrin ring result in higher vesicle and cell uptake. Binding in mitochondria is dependent on the PS lipophilicity and on the electrochemical membrane potential, i.e., in uncoupled mitochondria PS binding decreases by up to 53%. The porphyrin substituted with octyl groups (TC8PyP) is the compound that is most enriched in mitochondria, and its zinc derivative (ZnTC8PyP) has the highest global uptake. The stronger membrane interaction of the zinc-substituted porphyrins is attributed to a complexing effect with phosphate groups of the phospholipids. Zinc insertion was also shown to decrease the interaction with isolated mitochondria and with the mitochondria of HeLa cells, an effect that has been explained by the particular characteristics of the mitochondrial internal membrane. Phototoxicity was shown to increase proportionally with membrane binding efficiency, which is attributed to favorable membrane interactions which allow more efficient membrane photooxidation. For this series of compounds, photodynamic efficiency is directly proportional to the membrane binding and cell uptake, but it is not totally related to mitochondrial targeting.

  14. Synthesis, spectroscopic, and photophysical characterization and photosensitizing activity toward prokaryotic and eukaryotic cells of porphyrin-magainin and -buforin conjugates.

    Science.gov (United States)

    Dosselli, Ryan; Ruiz-González, Rubén; Moret, Francesca; Agnolon, Valentina; Compagnin, Chiara; Mognato, Maddalena; Sella, Valentina; Agut, Montserrat; Nonell, Santi; Gobbo, Marina; Reddi, Elena

    2014-02-27

    Cationic antimicrobial peptides (CAMPs) and photodynamic therapy (PDT) are attractive tools to combat infectious diseases and to stem further development of antibiotic resistance. In an attempt to increase the efficiency of bacteria inactivation, we conjugated a PDT photosensitizer, cationic or neutral porphyrin, to a CAMP, buforin or magainin. The neutral and hydrophobic porphyrin, which is not photoactive per se against Gram-negative bacteria, efficiently photoinactivated Escherichia coli after conjugation to either buforin or magainin. Conjugation to magainin resulted in the considerable strengthening of the cationic and hydrophilic porphyrin's interaction with the bacterial cells, as shown by the higher bacteria photoinactivation activity retained after washing the bacterial suspension. The porphyrin-peptide conjugates also exhibited strong interaction capability as well as photoactivity toward eukaryotic cells, namely, human fibroblasts. These findings suggest that these CAMPs have the potential to carry drugs and other types of cargo inside mammalian cells similar to cell-penetrating peptides.

  15. Properties of halogenated and sulfonated porphyrins relevant for the selection of photosensitizers in anticancer and antimicrobial therapies.

    Directory of Open Access Journals (Sweden)

    Barbara Pucelik

    Full Text Available The impact of substituents on the photochemical and biological properties of tetraphenylporphyrin-based photosensitizers for photodynamic therapy of cancer (PDT as well as photodynamic inactivation of microorganisms (PDI was examined. Spectroscopic and physicochemical properties were related with therapeutic efficacy in PDT of cancer and PDI of microbial cells in vitro. Less polar halogenated, sulfonamide porphyrins were most readily taken up by cells compared to hydrophilic and anionic porphyrins. The uptake and PDT of a hydrophilic porphyrin was significantly enhanced with incorporation in polymeric micelles (Pluronic L121. Photodynamic inactivation studies were performed against Gram-positive (S. aureus, E. faecalis, Gram-negative bacteria (E. coli, P. aeruginosa, S. marcescens and fungal yeast (C. albicans. We observed a 6 logs reduction of S. aureus after irradiation (10 J/cm2 in the presence of 20 μM of hydrophilic porphyrin, but this was not improved with incorporation in Pluronic L121. A 2-3 logs reduction was obtained for E. coli using similar doses, and a decrease of 3-4 logs was achieved for C. albicans. Rational substitution of tetraphenylporphyrins improves their photodynamic properties and informs on strategies to obtain photosensitizers for efficient PDT and PDI. However, the design of the photosensitizers must be accompanied by the development of tailored drug formulations.

  16. EXPERIMENTAL CONFIRMATION FOR SELECTION OF IRRADIATION REGIMENS FOR INTRAPERITONEAL PHOTODYNAMIC THERAPY WITH PORPHYRIN AND PHTHALOCYANINE PHOTOSENSITIZERS

    Directory of Open Access Journals (Sweden)

    A. A. Pankratov

    2017-01-01

    Full Text Available Optimized irradiation regimens for intraperitoneal photodynamic therapy with porphyrin and phthalocyanine photosensitizers are determined in in vitro and in vivo studies.The experimental  study on НЕр2 cell line showed that reduce of power density for constant  light dose increased significantly the efficacy of photodynamic therapy (the reduce of power density from 20-80 mW/cm2 to 10 mW/cm2 had the same results (90% cell death for half as much concentration of the photosensitizer.The obtained results were confirmed in vivo in mice with grafted tumor S-37. For light dose of 90 J/cm2  and power density of 25 mW/cm2 none of animals in the experimental  group had total resorption of the tumor. For the same light dose and decrease  of power density to 12 mW/cm2  total tumor resorption was achieved in 34% of animals, 66% of animals died from phototoxic  shock. For twofold decrease  of light dose – to 45 J/cm2  with the same low-intensity power density (12 mW/cm2 we managed total tumor resorption in 100% of animals.In the following studies of optimized irradiation regimen for intrapleural photodynamic therapy the reaction of intact peritoneum of rats on photodynamic exposure was assessed and optimized parameters of laser irradiation, which did not cause necrosis and intense inflammatory reaction of peritoneum, were determined – light dose of 10 J/cm2  with power density of mW/cm2.Thus, the reasonability for use of low-intensity regimens of irradiation for intraperitoneal photodynamic therapy was confirmed experimentally with possibility of high efficacy of treatment without inflammatory reactions of peritoneum.

  17. Structure Optimization of 21,23-Core-Modified Porphyrins Absorbing Long-Wavelength Light as Potential Photosensitizers Against Breast Cancer Cells

    Science.gov (United States)

    2008-04-01

    porphyrin and induction of apoptosis. Journal of Photochemistry and Photobiology B: Biology 2006, 85, 155-162. 4. You, Y .; Daniels, T. S.; Dominiak, P. M...Cells were loaded with 0.4% trypan blue on a hematocytometer slide at the ratio 1:1 (v/v) and analyzed by light microscopy. The percentage of dead...Modified Porphyrins Absorbing Long- Wavelength Light as Potential Photosensitizers Against Breast Cancer Cells PRINCIPAL INVESTIGATOR: Michael R

  18. Influence of aqueous media properties on aggregation and solubility of four structurally related meso-porphyrin photosensitizers evaluated by spectrophotometric measurements.

    Science.gov (United States)

    Sobczyński, J; Tønnesen, H H; Kristensen, S

    2013-02-01

    Porphyrin photosensitizers tend to aggregate in aqueous solutions even in the micromolar concentration range. This is a challenge during formulation of e.g., parenteral preparations for photodynamic cancer therapy, or preparations for local or topical administration in antimicrobial photodynamic therapy. Monomerization is essential to achieve biocompatible drug formulations of high bioavailability and physiological response (i.e., photoreactivity) and low toxicity. The aggregation and solubilization of four structurally related meso-tetraphenyl porphyrin photosensitizers with nonionic (4-hydroxy), anionic (4-sulphonate; 4-carboxy) and cationic (4-trimethylanilinium) substituents were evaluated in various vehicles by use of UV-Vis spectroscopy. Substituents, overall charge and charge distribution influenced the pKa-values and interaction of the porphyrins with different solvents, excipients and impurities. Modification of medium polarity and solubilization by the nonionic surfactant Tween 80 adjusted the acid-base equilibria and increased the solubility by reduction of porphyrin aggregation. The selected porphyrins were sensitive towards ionic strength, temperature and inorganic impurities to various extents. The results will be further used during development of parenteral and topical formulations of porphyrin photosensitizers for use in photodynamic therapy of cancer and bacterial infections.

  19. In vitro and in vivo antitumor activity of a novel porphyrin-based photosensitizer for photodynamic therapy.

    Science.gov (United States)

    Chen, Jing-Jing; Hong, Ge; Gao, Li-Jing; Liu, Tian-Jun; Cao, Wen-Jun

    2015-09-01

    Photodynamic therapy (PDT) is a promising treatment in cancer therapy, based on the use of a photosensitizer activated by visible light in the presence of oxygen. Nowadays significant research efforts have been focused on finding a new photosensitizer. In the present paper, the antitumor effects of a novel porphyrin-based photosensitizer, {Carboxymethyl-[2-(carboxymethyl-{[4-(10,15,20-triphenylporphyrin-5-yl)-phenylcarbamoyl]-methyl}-amino)-ethyl]-amino}-acetic acid (ATPP-EDTA) on two types of human malignant tumor cells in vitro and a gastric cancer model in nude mice, were evaluated. The PDT efficacy with ATPP-EDTA in vitro was assessed by MTT assay. The intracellular accumulation was detected with fluorescence spectrometer, and the intracellular distribution was determined by laser scanning confocal microscopy. The mode of cell death was investigated by Hoechst 33342 staining and flow cytometer. BGC823-derived xenograft tumor model was established to explore the in vivo antitumor effects of ATPP-EDTA. ATPP-EDTA exhibited intense phototoxicity on both cell lines in vitro in concentration- and light dose-dependent manners meanwhile imposing minimal dark cytotoxicity. The accumulation of ATPP-EDTA in two malignant cell lines was time-dependent and prior compared to normal cells. It was mainly localized at lysosomes, but induced cell death by apoptotic pathway. ATPP-EDTA significantly inhibited the growth of BGC823 tumors in nude mice (160 mW/cm(2), 100 J/cm(2)). Present studies suggest that ATPP-EDTA is an effective photosensitizer for PDT to tumors. It distributed in lysosomes and caused cell apoptosis. ATPP-EDTA, as a novel photosensitizer, has a great potential for human gastric cancer treatment in PDT and deserves further investigations.

  20. Comparison of two photosensitizers Al(III) phthalocyanine chloride tetrasulfonic acid and meso-tetrakis(4-sulfonatophenyl)porphyrin in the photooxidation of n-butylparaben

    Czech Academy of Sciences Publication Activity Database

    Gmurek, M.; Kubát, Pavel; Mosinger, Jiří; Miller, J. S.

    2011-01-01

    Roč. 223, č. 1 (2011), s. 50-56 ISSN 1010-6030 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40320502 Keywords : photosensitization * porphyrin * phthalocyanine Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.421, year: 2011

  1. Porphyrins

    Science.gov (United States)

    Gotelli, George R.; Wall, Jeffrey H.; Kabra, Pokar M.; Marton, Laurence J.

    Historically the term porphyria has been used since it was coined in 1871 to describe a purple colored material extracted from pathological feces (1). The first case of porphyria was reported in 1874, (2, 3), but until the 1930 Nobel Prize winning work of Hans Fischer on the synthesis of protoporphyrin, there was little more than academic interest in porphyrin analysis. During the forty years between 1930 and 1970, the biosynthetic pathways leading to the formation of heme, and the details of porphyrin metabolism, were elucidated. During this time quantitative methods for porphyrins in biological fluids used complex and laborious solvent extraction techniques, requiring large sample volumes and hours to complete. We now know that these methods only partially separated the complex mixture of porphyrins found in biological fluids. These solvent extraction procedures fractionated the porphyrins into two broad groups, uroporphyrins (octacarboxylic) and coproporphyrins (tetracarboxylic). However, intermediate carboxylated porphyrin containing 2, 3, 5, 6, and 7 carboxyl groups are now known to exist in normal and pathlogical excreta, which were not differentiated, but which were included in the two broad uroporphyrin and copropophyrin groups.

  2. Visualization of Porphyrin-Based Photosensitizer Distribution from Fluorescence Images In Vivo Using an Optimized RGB Camera

    Science.gov (United States)

    Liu, L.; Huang, Zh.; Qiu, Zh.; Li, B.

    2018-01-01

    A handheld RGB camera was developed to monitor the in vivo distribution of porphyrin-based photosensitizer (PS) hematoporphyrin monomethyl ether (HMME) in blood vessels during photodynamic therapy (PDT). The focal length, f-number, International Standardization Organization (ISO) sensitivity, and shutter speed of the camera were optimized for the solution sample with various HMME concentrations. After the parameter optimization, it was found that the red intensity value of the fluorescence image was linearly related to the fluorescence intensity under investigated conditions. The RGB camera was then used to monitor the in vivo distribution of HMME in blood vessels in a skin-fold window chamber model. The red intensity value of the recorded RGB fluorescence image was found to be linearly correlated to HMME concentrations in the range 0-24 μM. Significant differences in the red to green intensity ratios were observed between the blood vessels and the surrounding tissue.

  3. Nanoparticles with Embedded Porphyrin Photosensitizers for Photooxidation Reactions and Continuous Oxygen Sensing

    Czech Academy of Sciences Publication Activity Database

    Kubát, Pavel; Henke, P.; Berzediová, V.; Štěpánek, M.; Lang, Kamil; Mosinger, Jiří

    2017-01-01

    Roč. 9, č. 41 (2017), s. 36229-36238 ISSN 1944-8244 R&D Projects: GA ČR(CZ) GA16-15020S Institutional support: RVO:61388955 ; RVO:61388980 Keywords : photooxidation * polystyrene nanoparticles * porphyrins Subject RIV: CF - Physical ; Theoretical Chemistry; CA - Inorganic Chemistry (UACH-T) OBOR OECD: Physical chemistry; Inorganic and nuclear chemistry (UACH-T) Impact factor: 7.504, year: 2016

  4. Potentiation by potassium iodide reveals that the anionic porphyrin TPPS4 is a surprisingly effective photosensitizer for antimicrobial photodynamic inactivation.

    Science.gov (United States)

    Huang, Liyi; El-Hussein, Ahmed; Xuan, Weijun; Hamblin, Michael R

    2018-01-01

    We recently reported that addition of the non-toxic salt, potassium iodide can potentiate antimicrobial photodynamic inactivation of a broad-spectrum of microorganisms, producing many extra logs of killing. If the photosensitizer (PS) can bind to the microbial cells, then delivering light in the presence of KI produces short-lived reactive iodine species, while if the cells are added after light the killing is caused by molecular iodine produced as a result of singlet oxygen-mediated oxidation of iodide. In an attempt to show the importance of PS-bacterial binding, we compared two charged porphyrins, TPPS4 (thought to be anionic and not able to bind to Gram-negative bacteria) and TMPyP4 (considered cationic and well able to bind to bacteria). As expected TPPS4+light did not kill Gram-negative Escherichia coli, but surprisingly when 100mM KI was added, it was highly effective (eradication at 200nM+10J/cm 2 of 415nm light). TPPS4 was more effective than TMPyP4 in eradicating the Gram-positive bacteria, methicillin-resistant Staphylococcus aureus and the fungal yeast Candida albicans (regardless of KI). TPPS4 was also highly active against E. coli after a centrifugation step when KI was added, suggesting that the supposedly anionic porphyrin bound to bacteria and Candida. This was confirmed by uptake experiments. We compared the phthalocyanine tetrasulfonate derivative (ClAlPCS4), which did not bind to bacteria or allow KI-mediated killing of E. coli after a spin, suggesting it was truly anionic. We conclude that TPPS4 behaves as if it has some cationic character in the presence of bacteria, which may be related to its delivery from suppliers in the form of a dihydrochloride salt. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Prospects of radical-interacting porphyrin photosensitizers and their possible use in photodynamic therapy

    Science.gov (United States)

    Gal, Dezso; Shuliakovskaya, T.; Vidoczy, Tamas; Elzemzam, Saleh; Vasvari, Gabor; Suemegi, L.; Kuti, Zsolt

    1994-03-01

    Based on literature data obtained in various fields with respect to studies on the role of free radicals in biology and on the kinetics of triplet-doublet interactions, it is suggested that excited photosensitizers react in vivo with free radicals formed in malignant tissues during photodynamic therapy (PDT) and this interaction competes with sensitizer-radical + molecule and the singlet oxygen mediated effects. Experimental results by laser flash photolysis and electron spin resonance revealed that sensitizer applied in PDT react with stable free radicals presumably both by energy transfer and electron transfer.

  6. Effects of a novel porphyrin-based photosensitizer on sensitive and multidrug-resistant human gastric cancer cell lines.

    Science.gov (United States)

    Chen, Jingjing; Mao, Lina; Liu, Shuping; Liang, Yanling; Wang, Sicheng; Wang, Yeyu; Zhao, Qiang; Zhang, Xiaojing; Che, Yanjun; Gao, Lijing; Liu, Tianjun

    2015-10-01

    Photodynamic therapy (PDT) has been considered to be a possible candidate approach in combating multidrug resistance (MDR) phenomenon during the treatment of cancer. To investigate the photocytotoxicity of a novel porphyrin-based photosensitizer, meso-5-[ρ-DTPA-aminophenyl]-10, 15, 20-triphenyl-porhyrin (DTP) (Fig. 1A), on MDR cells, the intracellular DTP uptake, phototoxicity and subcellular DTP localization were studied by using a human gastric cancer MGC803 cell line and its paclitaxel selected subline MGC803/PA expressing MDR phenotype. No significant difference was observed in intracellular DTP accumulation between sensitive and resistant cell lines after exposure to 1.56 μM concentration for 6h. DTP-PDT induced significant photocytotoxicity on both MGC803 and MGC803/PA cell lines and the photokilling was greater in MGC803 cell line in comparison to MGC803/PA. The fluence that caused 50% cell death was 4.42 and 6.29 J/cm(2) in MGC803 and MGC803/PA cell lines, respectively. The presence of Pgp inhibitors verapamil and cyclosporin A could not modify the intracellular DTP level in MGC803/PA cell line and the phototoxic effects. DTP was localized at lysosomes of MGC803 cell line but at lysosomes and mitochondria of MGC803/PA. Our results indicated that DTP-mediated PDT could eradicate gastric cancer cells whether or not they express MDR although the efficacy is slightly reduced in the MDR cells. The photokilling in MDR cells could not be altered by MDR inhibitor verapamil. The slightly different photocytotoxicity between sensitive and resistant cell lines could not explained by classical Pgp MDR and might be attributed to the differential intracellular DTP localization sites. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Application of an octa-anionic 5,10,15,20-tetra[3,5-(nido-carboranylmethyl)phenyl]porphyrin (H2OCP) as dual sensitizer for BNCT and PDT

    Science.gov (United States)

    The applications of the octa-anionic 5,10,15,20-tetra[3,5-(nidocarboranylmethyl) phenyl]porphyrin (H2OCP) as a boron delivery agent in boron neutron capture therapy (BNCT) and a photosensitizer in photodynamic therapy (PDT) have been investigated. Using F98 Rat glioma cells, we evaluated the cytotox...

  8. Synthesis, characterization and ab initio investigation of a panchromatic ullazine-porphyrin photosensitizer for dye-sensitized solar cells

    NARCIS (Netherlands)

    Mathew, S.; Astani, N.A.; Curchod, B.F.E.; Delcamp, J.H.; Marszalek, M.; Frey, J.; Rothlisberger, U.; Nazeeruddin, M.K.; Grätzel, M.

    2016-01-01

    An ullazine unit was employed as a donor moiety in a donor-π-acceptor (D-π-A) motif, employing the porphyrin macrocycle as a π-system. Synthesis of this ullazine-porphyrin dyad containing sensitizer (SM63) was achieved and an investigation of the electrochemical and spectroscopic properties of this

  9. An action spectrum for blue and near ultraviolet inactivation of Propionibacterium acnes; with emphasis on a possible porphyrin photosensitization

    International Nuclear Information System (INIS)

    Kjeldstad, B.; Johnsson, A.

    1986-01-01

    Propionibacterium acnes (P. acnes), grown on Eagles medium with different pH, were irradiated with monochromatic light in the range 320 to 440 nm. Different pH leads to different porphyrin concentrations in the cells. The light sensitivity of the bacteria was estimated from the reduction in their ability to form colonies after radiation. The sensitivity was highest for the lowest wavelength (320 nm), and decreased continuously with increasing wavelength up to 380 nm. In the region between 380 and 440 nm there was a second maximum (at 415 nm) which corresponds to the maximum absorption of the fluorescing porphyrins in P. acnes. The sensitivity to 415 nm light was found to be dependent on the endogenous porphyrin concentration in the cells, while the sensitivity to 320 nm radiation was independent of the amount of porphyrin present. These results indicate that porphyrins produced by the bacteria are important for the light sensitivity of these bacteria. (author)

  10. Binding of palladium (II) 5, 10, 15, 20-tetrakis (4-sulfonatophenyl) porphyrin to a lectin for photosensitizer targeted delivery

    Czech Academy of Sciences Publication Activity Database

    Bogoeva, V.; Petrova, L.; Kubát, Pavel

    2015-01-01

    Roč. 153, DEC 2015 (2015), s. 276-280 ISSN 1011-1344 R&D Projects: GA ČR GA13-12496S Institutional support: RVO:61388955 Keywords : palladium porphyrin * concavalin A * fluorescence Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.035, year: 2015

  11. Composites with Photosensitive 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin Entrapped into Silica Gels

    Czech Academy of Sciences Publication Activity Database

    Rychtáriková, Renata; Šabata, Stanislav; Hetflejš, Jiří; Kuncová, Gabriela

    2012-01-01

    Roč. 61, č. 1 (2012), s. 119-125 ISSN 0928-0707 R&D Projects: GA MŠk ME 892 Institutional research plan: CEZ:AV0Z40720504 Keywords : sol-gel * photosensitizer * immobilization Subject RIV: CC - Organic Chemistry Impact factor: 1.660, year: 2012

  12. Dispersion of the Photosensitizer 5,10,15,20-Tetrakis(4-Sulfonatophenyl)-porphyrin by the Amphiphilic Polymer Poly(vinylpirrolidone) in Highly Porous Solid Materials Designed for Photodynamic Therapy.

    Science.gov (United States)

    Díaz, Claudia; Catalán-Toledo, José; Flores, Mario E; Orellana, Sandra L; Pesenti, Héctor; Lisoni, Judit; Moreno-Villoslada, Ignacio

    2017-08-03

    The ability of the amphiphilic and biocompatible poly(vinylpyrrolidone) to avoid self-aggregation of the photosensitizer 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin in aqueous solution in the presence of the biocompatible polycation chitosan, polymer that induces the dye self-aggregation, is shown. This is related to the tendency of the dye to undergo preferential solvation by the amphiphilic polymer. Importantly, the dispersant ability of this polymer is transferred to the solid state. Thus, aerogels made of the biocompatible polymers chitosan and chondroitin sulfate, and containing the photosensitizer dispersed by the amphiphilic polymer have been synthesized. Production of reactive oxygen species by the aerogel containing the amphiphilic polymer was faster than when the polymer was absent, correlating with the relative concentration of dyes dispersed as monomers. The aerogels presented here constitute low cost biocompatible materials bearing a conventional photosensitizer for photodynamic therapy, easy to produce, store, transport, and manage in clinical practice.

  13. Four Gadolinium(III) Complexes Appended to a Porphyrin: A Water-Soluble Molecular Theranostic Agent with Remarkable Relaxivity Suited for MRI Tracking of the Photosensitizer.

    Science.gov (United States)

    Sour, Angélique; Jenni, Sébastien; Ortí-Suárez, Ana; Schmitt, Julie; Heitz, Valérie; Bolze, Frédéric; Loureiro de Sousa, Paulo; Po, Chrystelle; Bonnet, Célia S; Pallier, Agnès; Tóth, Éva; Ventura, Barbara

    2016-05-02

    A molecular theranostic agent for magnetic resonance imaging (MRI) and photodynamic therapy (PDT) consisting of four [GdDTTA](-) complexes (DTTA(4-) = diethylenetriamine-N,N,N″,N″-tetraacetate) linked to a meso-tetraphenylporphyrin core, as well as its yttrium(III) analogue, was synthesized. A variety of physicochemical methods were used to characterize the gadolinium(III) conjugate 1 both as an MRI contrast agent and as a photosensitizer. The proton relaxivity measured in H2O at 20 MHz and 25 °C, r1 = 43.7 mmol(-1) s(-1) per gadolinium center, is the highest reported for a bishydrated gadolinium(III)-based contrast agent of medium size and can be related to the rigidity of the molecule. The complex displays also a remarkable singlet oxygen quantum yield of ϕΔ = 0.45 in H2O, similar to that of a meso-tetrasulfonated porphyrin. We also evidenced the ability of the gadolinium(III) conjugate to penetrate in cancer cells with low cytotoxicity. Its phototoxicity on Hela cells was evaluated following incubation at low micromolar concentration and moderate light irradiation (21 J cm(-2)) induced 50% of cell death. Altogether, these results demonstrate the high potential of this conjugate as a theranostic agent for MRI and PDT.

  14. Biodistribution and pharmacokinetic studies of a porphyrin dimer photosensitizer (Oxdime) by fluorescence imaging and spectroscopy in mice bearing xenograft tumors.

    Science.gov (United States)

    Khurana, Mamta; Ulrich, Sébastien; Kim, Anthony; Moriyama, Yumi; Netchev, George; Akens, Margarete K; Anderson, Harry L; Wilson, Brian C

    2012-01-01

    Herein, we present a study of the pharmacokinetics and biodistribution of a butadiyne-linked conjugated porphyrin dimer (Oxdime) designed to have high near-infrared (NIR) 2-photon absorption cross-section for photodynamic therapy (PDT). Changes in biodistribution over time were monitored in mice carrying B16-F10 melanoma xenografts, following intravenous injection. Using fluorescence imaging of live animals and analyzing isolated organs ex vivo at different time points between 30 min and 24 h after injection, accumulation of Oxdime was measured in several organs (heart, kidney and liver) and in tumor. The concentration in the plasma was about 5-10 times higher than in other tissues. The fluorescence signal peaked at 3-12 h after injection in most tissues, including the tumor and the plasma. The change in the fluorescence emission spectrum of the sensitizer over time was also monitored and a shift in the maximum from 800 to 740 nm was observed over 24 h, showing that the Oxdime is metabolized. Significant quantities accumulated in the tumor, indicating that this PDT sensitizer may be promising for cancer treatment. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

  15. Photodynamic therapy with TMPyP - Porphyrine induces mitotic catastrophe and microtubule disorganization in HeLa and G361 cells, a comprehensive view of the action of the photosensitizer.

    Science.gov (United States)

    Cenklová, Věra

    2017-08-01

    Photodynamic therapy (PDT) is a useful tool against cancer and various other diseases. PDT is capable to induce different cell death mechanisms, due to the PDT evoked reactive oxygen species (ROS) production and is dose dependent. It is known that cytoskeleton is responsible for numerous cell functions, including cell division, maintenance of cell shape, their adhesion ability and movement. PDT initiated redistribution and subsequent disintegration of cytoskeletal components that precedes cell death. Here was present our results in HeLa and G361 cells subjected to sublethal PDT treatments using α,β,χ,δ porphyrin-Tetrakis (1-methylpyridinium-4-yl) p-Toluenesulfonate porphyrin (TMPyP). The photosensitizer (PS) induced transient increasing of mitotic index (MI) observable early after PDT, cell cycle arrest, microtubule (MTs) disorganization of interphase cells, aberrant mitosis and formation of rounded cells with partial loss of adherence. Some cells were partly resistant to PDT induced MTs disorganization. The differences between both cell lines to PDT response were described. This is the first evidence of TMPyP - PDT induced microtubule disorganization and the cell death mechanisms known as mitotic catastrophe and the first detail analysis of microtubule aberrations of mitotic and interphase cells in HeLa and G361 cell lines. New modification of techniques of protein immunolabeling was developed. Copyright © 2017. Published by Elsevier B.V.

  16. New photosensitizers for photodynamic therapy

    Science.gov (United States)

    Abrahamse, Heidi; Hamblin, Michael R.

    2016-01-01

    Photodynamic therapy (PDT) was discovered more than 100 years ago, and has since become a well-studied therapy for cancer and various non-malignant diseases including infections. PDT uses photosensitizers (PSs, non-toxic dyes) that are activated by absorption of visible light to initially form the excited singlet state, followed by transition to the long-lived excited triplet state. This triplet state can undergo photochemical reactions in the presence of oxygen to form reactive oxygen species (including singlet oxygen) that can destroy cancer cells, pathogenic microbes and unwanted tissue. The dual-specificity of PDT relies on accumulation of the PS in diseased tissue and also on localized light delivery. Tetrapyrrole structures such as porphyrins, chlorins, bacteriochlorins and phthalocyanines with appropriate functionalization have been widely investigated in PDT, and several compounds have received clinical approval. Other molecular structures including the synthetic dyes classes as phenothiazinium, squaraine and BODIPY (boron-dipyrromethene), transition metal complexes, and natural products such as hypericin, riboflavin and curcumin have been investigated. Targeted PDT uses PSs conjugated to antibodies, peptides, proteins and other ligands with specific cellular receptors. Nanotechnology has made a significant contribution to PDT, giving rise to approaches such as nanoparticle delivery, fullerene-based PSs, titania photocatalysis, and the use of upconverting nanoparticles to increase light penetration into tissue. Future directions include photochemical internalization, genetically encoded protein PSs, theranostics, two-photon absorption PDT, and sonodynamic therapy using ultrasound. PMID:26862179

  17. Porphyrin-Azobenzene-Bodipy Triads: Syntheses, Structures, and Photophysical Properties.

    Science.gov (United States)

    Yin, Bangshao; Kim, Taeyeon; Zhou, Mingbo; Huang, Weiming; Kim, Dongho; Song, Jianxin

    2017-05-19

    Cyclic and acyclic azobenzene bridged porphyrin-dipyrrin derivatives were successfully prepared via Suzuki-Miyaura coupling reaction of α,α'-diborylated dipyrromethane with bromoazophenyl porphyrin or reaction of borylated porphyrin with dibromoazophenyl dipyrrin, and the corresponding porphyrin-Bodipy derivatives were obtained by subsequent boron complexation. The cyclic porphyrin-dipyrrin compound 3Ni was confirmed by X-ray diffraction. The low fluorescence quantum yields of azobenzene bridged porphyrin-Bodipy can be ascribed to the presence of the intramolecular charge transfer state.

  18. Photosensitized oxidation of DNA and its components

    International Nuclear Information System (INIS)

    Decarroz, Chantal.

    1982-09-01

    Chemical changes in DNA components during the photodynamic effect are responsible for Mutagenic and carcinogenic phenomena. Basically two competitive mechanisns involving respectively a charge transfer (type I) and singlet oxygen (type II) are implicated in reactions photo-sensitized by different agents (acridines, phenothiazines, porphyrins, flavins, psoralenes...). A study of the photosensitized oxidation of DNA itself was approached through characterization of the main final products in the case of purine nucleosides. Methyl-2 naphthoquinone - 1,4 (vitamin K 3 ) displays a special photosensitization mechanism involving a cation radical type of intermediary [fr

  19. Heptaphyrins: Expanded porphyrins with seven heterocyclic rings

    Indian Academy of Sciences (India)

    Unknown

    ring inversion. 1. Introduction. The syntheses of expanded porphyrins continue to attract the attention of chemists because of their diverse biological applications such as: anion receptors, photosensitizing agents, MRI contrast agents1 etc. They are also of interest, theoretically, to study the fundamental property of aromaticity ...

  20. Porphyrin Tests

    Science.gov (United States)

    ... and Iron-binding Capacity (TIBC, UIBC) Trichomonas Testing Triglycerides Troponin Tryptase Tumor Markers Uric Acid Urinalysis Urine ... acute attack Table adapted from: "Iron and porphyrin metabolism," Clinical Chemistry: Theory, Analysis and Correlation , courtesy of ...

  1. Photoinduced oxidation of a water-soluble manganese(III) porphyrin

    Science.gov (United States)

    Maliyackel, Anthony C.; Otvos, John W.; Spreer, Larry O.; Calvin, Melvin

    1986-01-01

    The photoinduced oxidation of tetra(N-methyl-4-pyridyl)porphyrinmanganese(III) has been achieved in homogeneous solution. The manganese porphyrin was used as an electron donor in a three-component system with tris-(2,2′-bipyridine)ruthenium(II) as the photosensitizer and chloropentaamminecobalt(III) as the electron acceptor. The photooxidized manganese porphyrin is unstable in aqueous solution, reverting to the starting manganese(III) porphyrin. The oxidation of manganese(III) porphyrin and the subsequent reduction of the oxidized porphyrin can be cycled repeatedly. PMID:16593699

  2. Interaction of porphyrins with CdTe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xing; Liu Zhongxin; Ma Lun; Hossu, Marius; Chen Wei, E-mail: weichen@uta.edu [Department of Physics, University of Texas at Arlington, Box 19059 Arlington, TX 76019 (United States)

    2011-05-13

    Porphyrins may be used as photosensitizers for photodynamic therapy, photocatalysts for organic pollutant dissociation, agents for medical imaging and diagnostics, applications in luminescence and electronics. The detection of porphyrins is significantly important and here the interaction of protoporphyrin-IX (PPIX) with CdTe quantum dots was studied. It was observed that the luminescence of CdTe quantum dots was quenched dramatically in the presence of PPIX. When CdTe quantum dots were embedded into silica layers, almost no quenching by PPIX was observed. This indicates that PPIX may interact and alter CdTe quantum dots and thus quench their luminescence. The oxidation of the stabilizers such as thioglycolic acid (TGA) as well as the nanoparticles by the singlet oxygen generated from PPIX is most likely responsible for the luminescence quenching. The quenching of quantum dot luminescence by porphyrins may provide a new method for photosensitizer detection.

  3. Interaction of porphyrins with CdTe quantum dots

    International Nuclear Information System (INIS)

    Zhang Xing; Liu Zhongxin; Ma Lun; Hossu, Marius; Chen Wei

    2011-01-01

    Porphyrins may be used as photosensitizers for photodynamic therapy, photocatalysts for organic pollutant dissociation, agents for medical imaging and diagnostics, applications in luminescence and electronics. The detection of porphyrins is significantly important and here the interaction of protoporphyrin-IX (PPIX) with CdTe quantum dots was studied. It was observed that the luminescence of CdTe quantum dots was quenched dramatically in the presence of PPIX. When CdTe quantum dots were embedded into silica layers, almost no quenching by PPIX was observed. This indicates that PPIX may interact and alter CdTe quantum dots and thus quench their luminescence. The oxidation of the stabilizers such as thioglycolic acid (TGA) as well as the nanoparticles by the singlet oxygen generated from PPIX is most likely responsible for the luminescence quenching. The quenching of quantum dot luminescence by porphyrins may provide a new method for photosensitizer detection.

  4. Mechanism and efficiency of cell death of type II photosensitizers: effect of zinc chelation.

    Science.gov (United States)

    Pavani, Christiane; Iamamoto, Yassuko; Baptista, Maurício S

    2012-01-01

    A series of meso-substituted tetra-cationic porphyrins, which have methyl and octyl substituents, was studied in order to understand the effect of zinc chelation and photosensitizer subcellular localization in the mechanism of cell death. Zinc chelation does not change the photophysical properties of the photosensitizers (all molecules studied are type II photosensitizers) but affects considerably the interaction of the porphyrins with membranes, reducing mitochondrial accumulation. The total amount of intracellular reactive species induced by treating cells with photosensitizer and light is similar for zinc-chelated and free-base porphyrins that have the same alkyl substituent. Zinc-chelated porphyrins, which are poorly accumulated in mitochondria, show higher efficiency of cell death with features of apoptosis (higher MTT response compared with trypan blue staining, specific acridine orange/ethidium bromide staining, loss of mitochondrial transmembrane potential, stronger cytochrome c release and larger sub-G1 cell population), whereas nonchelated porphyrins, which are considerably more concentrated in mitochondria, triggered mainly necrotic cell death. We hypothesized that zinc-chelation protects the photoinduced properties of the porphyrins in the mitochondrial environment. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

  5. Inverted porphyrins and expanded porphyrins: An overview

    Indian Academy of Sciences (India)

    More recently, synthetic porphyrins and porphyrin-like macrocycles have attracted the attention of researchers due to their diverse applications as sensitizers for photodynamic therapy, MRI contrasting agents, and complexing agents for larger metal ions and also for their anion binding abilities. The number of -electrons in ...

  6. porphyrin and anthracene subunits

    Indian Academy of Sciences (India)

    Unknown

    rated to dryness under reduced pressure. The residue was dissolved in ≈50 .... spectrum of each of these axial-bonding type tin(IV) porphyrins showed only a low inten- sity peak due to the parent M+ ion. ..... However, this exercise clearly reveals that there is a near perpendicular juxtaposition of the porphyrin and the axial ...

  7. Arsenic and porphyrins.

    Science.gov (United States)

    Apostoli, P; Sarnico, M; Bavazzano, P; Bartoli, D

    2002-09-01

    To evaluate the possible effect of inorganic arsenic (iAs) and of its species on the urinary excretion of porphyrin homologues. Total porphyrins and their homologues (copro, penta, hexa, hepta, uroporphyrins) and arsenic species (trivalent and pentavalent As; monomethyl arsonic acid; dimethyl arsenic acid; arsenobetaine) were measured respectively by HPLC and HPLC-ICP MS in urine from 86 art glass workers exposed to iAs and from 54 controls. A significant increase in the excretion of penta and uroporphyrins was demonstrated for workers exposed to As; As3 was the species best correlated with urinary porphyrin excretion. The increase of urinary excretion for some porphyrin homologues appears to be consistent with the inhibition by As of URO-decarboxylase in the heme biosynthesis pathway. The determination of urinary porphyrin homologues could be useful to assess, on a group basis, some early effects of arsenic and to demonstrate possible individual susceptibility to the element. Copyright 2002 Wiley-Liss, Inc.

  8. Soluble porphyrin polymers

    Science.gov (United States)

    Gust, Jr., John Devens; Liddell, Paul Anthony

    2015-07-07

    Porphyrin polymers of Structure 1, where n is an integer (e.g., 1, 2, 3, 4, 5, or greater) ##STR00001## are synthesized by the method shown in FIGS. 2A and 2B. The porphyrin polymers of Structure 1 are soluble in organic solvents such as 2-MeTHF and the like, and can be synthesized in bulk (i.e., in processes other than electropolymerization). These porphyrin polymers have long excited state lifetimes, making the material suitable as an organic semiconductor for organic electronic devices including transistors and memories, as well as solar cells, sensors, light-emitting devices, and other opto-electronic devices.

  9. Functionalized expanded porphyrins

    Science.gov (United States)

    Sessler, Jonathan L; Pantos, Patricia J

    2013-11-12

    Disclosed are functionalized expanded porphyrins that can be used as spectrometric sensors for high-valent actinide cations. The disclosed functionalized expanded porphyrins have the advantage over unfunctionalized systems in that they can be immobilized via covalent attachment to a solid support comprising an inorganic or organic polymer or other common substrates. Substrates comprising the disclosed functionalized expanded porphyrins are also disclosed. Further, disclosed are methods of making the disclosed compounds (immobilized and free), methods of using them as sensors to detect high valent actinides, devices that comprise the disclosed compounds, and kits.

  10. Porphyrins - blood test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003372.htm Porphyrins blood test To use the sharing features on this page, ... blood or the urine . This article discusses the blood test. How the Test is Performed A blood sample ...

  11. Photosensitized oxidation of nicotinamide adenine dinucleotide by diethoxyphosphorus(V)tetraphenylporphyrin and its fluorinated derivative: Possibility of chain reaction

    Science.gov (United States)

    Hirakawa, Kazutaka; Murata, Atsushi

    2018-01-01

    Water-soluble porphyrins, diethoxyphosphorus(V)tetraphenylporphyrin (EtP(V)TPP) and its fluorinated analogue (FEtP(V)TPP), decreased the typical absorption around 340 nm of nicotinamide adenine dinucleotide (NADH) under visible light irradiation, indicating oxidative decomposition. A singlet oxygen quencher, sodium azide, and a triplet quencher, potassium iodide, slightly inhibited photosensitized NADH oxidation. However, these inhibitory effects were very small. Furthermore, the fluorescence lifetime of these P(V)porphyrins was decreased by NADH, suggesting the contribution of electron transfer to the singlet excited (S1) state of P(V)porphyrin. The redox potential measurement supports the electron transfer-mediated oxidation of NADH. The quantum yields of NADH photodecomposition by P(V)porphyrins could be estimated from the kinetic data and the effect of these quenchers on NADH oxidation. The obtained values suggest that the electron accepting by the S1 states of P(V)porphyrins triggers a chain reaction of NADH oxidation. This photosensitized reaction may play an important role in the photocytotoxicity of P(V)porphyrins. The axial ligand fluorination of P(V)porphyrins improved electron accepting ability. However, fluorination slightly suppressed static interaction with NADH, resulting in decreased oxidation quantum yield.

  12. Chlorin e6 fused with a cobalt-bis(dicarbollide) nanoparticle provides efficient boron delivery and photoinduced cytotoxicity in cancer cells.

    Science.gov (United States)

    Efremenko, Anastasija V; Ignatova, Anastasija A; Grin, Mikhail A; Sivaev, Igor B; Mironov, Andrey F; Bregadze, Vladimir I; Feofanov, Alexey V

    2014-01-01

    Further development of boron neutron capture therapy (BNCT) requires new neutronsensitizers with improved ability to deliver (10)B isotopes in cancer cells. Conjugation of boron nanoparticles with porphyrin derivatives is an attractive and recognized strategy to solve this task. We report on breakthroughs in the structural optimization of conjugates of chlorin e6 derivative with cobalt-bis(dicarbollide) nanoparticles resulting in the creation of dimethyl ester 13-carbomoylchlorin e6 [N-hexylamine-N'-ethoxyethoxy]-cobalt-bis(dicarbollide) (conjugate 1). Conjugate 1 is able to accumulate quickly and efficiently (distribution factor of 80) in cancer cells, thus delivering more than 10(9) boron atoms per cell when its extracellular concentration is more than 1 μmol L(-1). Also 1 is an active photosensitizer and is phototoxic towards human lung adenocarcinoma A549 cells at 80 nmol L(-1) (50% cell death). Photoinduced cytotoxicity of 1 is associated with lipid peroxidation, lysosome rupture and protease activity enhancement. Conjugate 1 fluoresces in the red region (670 nm), which is useful to monitor its accumulation and distribution in vivo. It is not toxic to cells without activation by neutrons or photons. Structural features that improve the functional properties of 1 are discussed. The properties of 1 warrant its preclinical evaluation as a multifunctional agent for BNCT, photodynamic therapy and fluorescent tumor diagnosis.

  13. Push-pull quinoidal porphyrins.

    Science.gov (United States)

    Smith, Martin J; Blake, Iain M; Clegg, William; Anderson, Harry L

    2018-05-01

    A family of push-pull quinoidal porphyrin monomers has been prepared from a meso-formyl porphyrin by bromination, thioacetal formation, palladium-catalyzed coupling with malononitrile and oxidation with DDQ. Attempts at extending this synthesis to a push-pull quinoidal/cumulenic porphyrin dimer were not successful. The crystal structures of the quinoidal porphyrins indicate that there is no significant contribution from singlet biradical or zwitterionic resonance forms. The crystal structure of an ethyne-linked porphyrin dimer shows that the torsion angle between the porphyrin units is only about 3°, in keeping with crystallographic results on related compounds, but contrasting with the torsion angle of about 35° predicted by computational studies. The free-base quinoidal porphyrin monomers form tightly π-stacked layer structures, despite their curved geometries and bulky aryl substituents.

  14. A novel chlorine derivative of Meso-tris(pentafluorophenyl)-4-pyridyl porphyrin: synthesis, photophysics and photochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Maestrin, Ana Paula J.; Ribeiro, Anderson O.; Tedesco, Antonio Claudio; Neri, Claudio R.; Vinhado, Fabio S.; Serra, Osvaldo A.; Martins, Patricia R.; Iamamoto, Yassuko [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Inst. de Quimica]. E-mail: oaserra@ffclrp.usp.br; Silva, Ana Margarida G.; Tome, Augusto C.; Neves, Maria G.P.M.S.; Cavaleiro, Jose A.S. [Universidade de Aveiro (Portugal). Dept. de Quimica]. E-mail: jcavaleiro@dq.ua.pt

    2004-12-01

    Photodynamic therapy (PDT) is based on the accumulation of a photosensitizer, such as a porphyrin or a chlorine, in a malignant tissue after its administration. Chlorins exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorine-containing systems even better candidates for PDT. In this contribution, we report the synthesis of 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin, (2) and its transformation to the novel chlorine derivatives 4, (5,10,20-tris(pentafluorophenyl)-15-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo [3,4-b]porphyrin and 5, (5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo[3,4-b]porphyrin) by 1,3-dipolar cycloaddition with an azomethine ylide. The new products have been characterized by UV-Vis, {sup 1}H NMR and FAB-MS. The photophysics, photochemical and photobleaching properties of chlorine 4 have been evaluated. Its quantum yield of photobleaching ({phi}{sub Pb}, mol Einstein{sup -1}) was 0.047{+-}0.014. In order to demonstrate the production of {sup 1}O{sub 2} when 4 is used as a photosensitizer, uric acid tests have been carried out. The results indicate that chlorine 4 can be considered a promising photosensitizer in PDT. (author)

  15. A novel chlorine derivative of Meso-tris(pentafluorophenyl)-4-pyridyl porphyrin: synthesis, photophysics and photochemical properties

    International Nuclear Information System (INIS)

    Maestrin, Ana Paula J.; Ribeiro, Anderson O.; Tedesco, Antonio Claudio; Neri, Claudio R.; Vinhado, Fabio S.; Serra, Osvaldo A.; Martins, Patricia R.; Iamamoto, Yassuko; Silva, Ana Margarida G.; Tome, Augusto C.; Neves, Maria G.P.M.S.; Cavaleiro, Jose A.S.

    2004-01-01

    Photodynamic therapy (PDT) is based on the accumulation of a photosensitizer, such as a porphyrin or a chlorine, in a malignant tissue after its administration. Chlorins exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorine-containing systems even better candidates for PDT. In this contribution, we report the synthesis of 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin, (2) and its transformation to the novel chlorine derivatives 4, (5,10,20-tris(pentafluorophenyl)-15-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo [3,4-b]porphyrin and 5, (5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo[3,4-b]porphyrin) by 1,3-dipolar cycloaddition with an azomethine ylide. The new products have been characterized by UV-Vis, 1 H NMR and FAB-MS. The photophysics, photochemical and photobleaching properties of chlorine 4 have been evaluated. Its quantum yield of photobleaching (φ Pb , mol Einstein -1 ) was 0.047±0.014. In order to demonstrate the production of 1 O 2 when 4 is used as a photosensitizer, uric acid tests have been carried out. The results indicate that chlorine 4 can be considered a promising photosensitizer in PDT. (author)

  16. porphyrin and anthracene subunits

    Indian Academy of Sciences (India)

    Unknown

    School of Chemistry, University of Hyderabad, Hyderabad 500 046, India ... This orientation dependence of EET could be analysed using Forster's dipole dipole mechanism. Keywords. Tin (IV)porphyrin; anthracene; spectroscopy; ... ions.1–10 Amongst these, a few studies have attempted to probe the orientation depen-.

  17. Photosensitivity in generalized epilepsies.

    Science.gov (United States)

    Poleon, Shervonne; Szaflarski, Jerzy P

    2017-03-01

    Photosensitivity, which is the hallmark of photosensitive epilepsy (PSE), is described as an abnormal EEG response to visual stimuli known as a photoparoxysmal response (PPR). The PPR is a well-recognized phenomenon, occurring in 2-14% of patients with epilepsy but its pathophysiology is not clearly understood. PPR is electrographically described as 2-5Hz spike, spike-wave, or slow wave complexes with frontal and paracentral prevalence. Diagnosis of PPR is confirmed using intermittent photic stimulation (IPS) as well as video monitoring. The PPR can be elicited by certain types of visual stimuli including flicker, high contrast gratings, moving patterns, and rapidly modulating luminance patterns which may be encountered during e.g., watching television, playing video games, or attending discotheques. Photosensitivity may present in different idiopathic (genetic) epilepsy syndromes e.g. juvenile myoclonic epilepsy (JME) as well as non-IGE syndromes e.g. severe myoclonic epilepsy of infancy. Consequently, PPR is present in patients with diverse seizure types including absence, myoclonic, and generalized tonic-clonic (GTC) seizures. Across syndromes, abnormalities in structural connectivity, functional connectivity, cortical excitability, cortical morphology, and behavioral and neuropsychological function have been reported. Treatment of photosensitivity includes antiepileptic drug administration, and the use of non-pharmacological agents, e.g. tinted or polarizing glasses, as well as occupational measures, e.g. avoidance of certain stimuli. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Photodynamic inactivation of Candida albicans by a tetracationic tentacle porphyrin and its analogue without intrinsic charges in presence of fluconazole.

    Science.gov (United States)

    Quiroga, Ezequiel D; Mora, S Jimena; Alvarez, M Gabriela; Durantini, Edgardo N

    2016-03-01

    The photodynamic inactivation mediated by 5,10,15,20-tetrakis[4-(3-N,N-dimethylaminopropoxy)phenyl]porphyrin (TAPP) and 5,10,15,20-tetrakis[4-(3-N,N,N-trimethylaminepropoxy)phenyl]porphyrin (TAPP(4+)) were compared in Candida albicans cells. A strong binding affinity was found between these porphyrins and the yeast cells. Photosensitized inactivation of C. albicans increased with both photosensitizer concentration and irradiation time. After 30 min irradiation, a high photoinactivation (∼5 log) was found for C. albicans treated with 5 μM porphyrin. Also, the photoinactivation of yeast cells was still elevated after two washing steps. However, the photocytotoxicity decreases with an increase in the cell density from 10(6) to 10(8) cells/mL. The high photodynamic activity of these porphyrins was also established by growth delay experiments. This C. albicans strain was susceptible to fluconazole with a MIC of 1.0 μg/mL. The effect of photosensitization and the action of fluconazole were combined to eradicate C. albicans. After a PDI treatment with 1 μM porphyrin and 30 min irradiation, the value of MIC decreased to 0.25 μg/mL. In addition, a complete arrest in cell growth was found by combining both effects. TAPP was similarly effective to photoinactivate C. albicans than TAPP(4+). This porphyrin without intrinsic positive charges contains basic amino groups, which can be protonated at physiological pH. Moreover, an enhancement in the antifungal action was found using both therapies because lower doses of the agents were required to achieve cell death. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Mitochondria-targeted cationic porphyrin-triphenylamine hybrids for enhanced two-photon photodynamic therapy.

    Science.gov (United States)

    Hammerer, Fabien; Poyer, Florent; Fourmois, Laura; Chen, Su; Garcia, Guillaume; Teulade-Fichou, Marie-Paule; Maillard, Philippe; Mahuteau-Betzer, Florence

    2018-01-01

    The proof of concept for two-photon activated photodynamic therapy has already been achieved for cancer treatment but the efficiency of this approach still heavily relies on the availability of photosensitizers combining high two-photon absorption and biocompatibility. In this line we recently reported on a series of porphyrin-triphenylamine hybrids which exhibit high singlet oxygen production quantum yield as well as high two-photon absorption cross-sections but with a very poor cellular internalization. We present herein new photosensitizers of the same porphyrin-triphenylamine hybrid series but bearing cationic charges which led to strongly enhanced water solubility and thus cellular penetration. In addition the new compounds have been found localized in mitochondria that are preferential target organelles for photodynamic therapy. Altogether the strongly improved properties of the new series combined with their specific mitochondrial localization lead to a significantly enhanced two-photon activated photodynamic therapy efficiency. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Charge effect on the photoinactivation of Gram-negative and Gram-positive bacteria by cationic meso-substituted porphyrins

    Directory of Open Access Journals (Sweden)

    Tomé Augusto C

    2009-04-01

    Full Text Available Abstract Background In recent times photodynamic antimicrobial therapy has been used to efficiently destroy Gram (+ and Gram (- bacteria using cationic porphyrins as photosensitizers. There is an increasing interest in this approach, namely in the search of photosensitizers with adequate structural features for an efficient photoinactivation process. In this study we propose to compare the efficiency of seven cationic porphyrins differing in meso-substituent groups, charge number and charge distribution, on the photodynamic inactivation of a Gram (+ bacterium (Enterococcus faecalis and of a Gram (- bacterium (Escherichia coli. The present study complements our previous work on the search for photosensitizers that might be considered good candidates for the photoinactivation of a large spectrum of environmental microorganisms. Results Bacterial suspension (107 CFU mL-1 treated with different photosensitizers concentrations (0.5, 1.0 and 5.0 μM were exposed to white light (40 W m-2 for a total light dose of 64.8 J cm-2. The most effective photosensitizers against both bacterial strains were the Tri-Py+-Me-PF and Tri-Py+-Me-CO2Me at 5.0 μM with a light fluence of 64.8 J cm-2, leading to > 7.0 log (> 99,999% of photoinactivation. The tetracationic porphyrin also proved to be a good photosensitizer against both bacterial strains. Both di-cationic and the monocationic porphyrins were the least effective ones. Conclusion The number of positive charges, the charge distribution in the porphyrins' structure and the meso-substituent groups seem to have different effects on the photoinactivation of both bacteria. As the Tri-Py+-Me-PF porphyrin provides the highest log reduction using lower light doses, this photosensitizer can efficiently photoinactivate a large spectrum of environmental bacteria. The complete inactivation of both bacterial strains with low light fluence (40 W m-2 means that the photodynamic approach can be applied to wastewater treatment

  1. Photosensitive Strip RETHGEM

    CERN Document Server

    Peskov, Vladimir; Nappi, E.; Oliveira, R.; Paic, G.; Pietropaolo, F.; Picchi, P.

    2008-01-01

    An innovative photosensitive gaseous detector, consisting of a GEM like amplification structure with double layered electrodes (instead of commonly used metallic ones) coated with a CsI reflective photocathode, is described. In one of our latest designs, the inner electrode consists of a metallic grid and the outer one is made of resistive strips; the latter are manufactured by a screen printing technology on the top of the metallic strips grid The inner metallic grid is used for 2D position measurements whereas the resistive layer provides an efficient spark protected operation at high gains - close to the breakdown limit. Detectors with active areas of 10cm x10cm and 10cm x20cm were tested under various conditions including the operation in photosensitive gas mixtures containing ethylferrocene or TMAE vapors. The new technique could have many applications requiring robust and reliable large area detectors for UV visualization, as for example, in Cherenkov imaging devices.

  2. Porphyrin-phospholipid interaction and ring metallation depending on the phospholipid polar head type.

    Science.gov (United States)

    Ramos, Ana P; Pavani, Christiane; Iamamoto, Yassuko; Zaniquelli, Maria E D

    2010-10-01

    The interaction between a hydrophobically modified 5,10,15,20-tetrakis(4-N-tetradecyl-pyridyl) porphyrin and three phospholipids: two negatively charged, DMPA (the sodium salt of dimyristoyl-sn-glycero-phosphatidyl acid) and DMPG (the sodium salt of 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)]) and a zwitterionic DMPC (dimyristoyl-sn-glycero-phosphatidylcholine), were studied by means of surface pressure isotherms and spectroscopic methods. The interaction results in partial or total metallation of the porphyrin with zinc ions in the presence of negatively charged phospholipids, as attested by UV-vis and luminescence spectroscopy of the transferred films. In the presence of the zwitterionic phospholipid no insertion of zinc ion in the porphyrin ring is detected. These results are relevant for the understanding of photosensitizer-lipid-carrier binding for use in photodynamic therapy. Copyright 2010 Elsevier Inc. All rights reserved.

  3. Synthesis and biological evaluation of porphyrin-polyamine conjugates as potential agents in photodynamic therapy

    International Nuclear Information System (INIS)

    Lamarche, Francois

    2004-01-01

    The synthesis of photosensitizers that specifically recognize tumoral cells constitutes a challenging step in the field of photodynamic therapy. To this end, we designed a new class of porphyrins linked to natural polyamines (spermidine, spermine). As a first step, we synthesized para and ortho-carboxy-propyl-oxy-phenyl-tritolyl-porphyrins bearing spermidine or spermine. Then, we designed two precursors, N4-aminobutyl-spermidine-Boc2 and N4-aminobutyl-spermine-Boc3. These derivatives have been fixed on carboxy-porphyrins, protoporphyrin IX and chlorin e6. These new compounds have been characterized by MALDI spectrometry, UV-Visible and 1 H NMR spectroscopy. They have been found to produce singlet oxygen. Biological activity study of these photosensitizers has been realized on K562 cell line, irradiated with fluorescent bulbs. In vitro tests of these porphyrins have shown their photo-cytotoxic activity and protoporphyrins-polyamines have been able to trigger early apoptotic events. Finally, preliminary results obtained with chlorin e6-polyamines, irradiated with red light, seem to show that these structures are good candidates for an application in PDT. (author) [fr

  4. porphyrin with single strand DNAs

    Indian Academy of Sciences (India)

    for organization of porphyrin molecules into extended assemblies, providing opportunities for construction of supramolecular structures.6–8 Among the porphyrin .... and consequently the mono- and bi-exponential nature of the decays were judged by the reduced chi-square. (χ2) values and distribution of the weighted ...

  5. Antimicrobial activity of new porphyrins of synthetic and natural origin

    Science.gov (United States)

    Gyulkhandanyan, Grigor V.; Ghazaryan, Robert K.; Paronyan, Marina H.; Ulikhanyan, Ghukas I.; Gyulkhandanyan, Aram G.; Sahakyan, Lida A.

    2012-03-01

    Antimicrobial photodynamic inactivation has been successfully used against Gram (+) microorganisms, but most of the photosensitizers (PSs) on Gram (-) bacteria acts weakly. PSs are the natural or synthetic origin dyes, mainly porphyrins. We have synthesized more than 100 new cationic porphyrins and metalloporphyrins with different functional groups (hydroxyethyl, butyl, allyl, methallyl) and metals (cobalt, iron, copper, zinc, silver and other); from the nettle have also been purified pheophytin (a+b) and pheophytin (a) and have synthesized their Ag-and Zn-metalloporphyrins. It was found that in the dark (cytotoxic) mode, the most highly efficiency against microorganisms showed Agmetalloporphyrins of both types of porphyrins (synthetic and natural). Metalloporphyrin of natural origin Ag-pheophytin (a + b) is a strong antibacterial agent and causes 100% death as the Gram (+) microorganisms (St. aureus and MRSA) and the Gram (-) microorganisms (E.coli and Salmonella). It is established that for the destruction of Gram (+) and Gram (-) microorganisms in photodynamic mode cationic water-soluble synthetic metalloporphyrins, especially Zn-TBut4PyP, many times more effective than pheophytins. In vivo conditions on mice established that the best therapeutic activity against various strains of the microorganism St. aureus has the synthetic metalloporphyrin Ag-TBut4PyP. It is significantly more efficient than known drug "Chlorophyllipt" (2.5-3 times) and leads the survival rate of animals up to 50-60%.

  6. Antimicrobial and anti-biofilm effect of a novel BODIPY photosensitizer against Pseudomonas aeruginosa PAO1

    DEFF Research Database (Denmark)

    Orlandi, Viviana Teresa; Rybtke, Morten; Caruso, Enrico

    2014-01-01

    Photodynamic therapy (PDT) combines the use of organic dyes (photosensitizers, PSs) and visible light in order to elicit a photo-oxidative stress which causes bacterial death. GD11, a recently synthesized PS belonging to the boron-dipyrromethene (BODIPY) class, was demonstrated to be efficient...

  7. Investigation of Porphyrin and Lipid Supramolecular Assemblies for Cancer Imaging and Therapy

    Science.gov (United States)

    Ng, Kenneth Ka-Seng

    Aerobic life on earth is made possible through the functions of the porphyrin. These colorful and ubiquitous chromophores are efficient at concentrating and converting sunlight into chemical energetic potential which sustain biological life. Humans have had a longstanding fascination with these molecules, especially for their applications in photodynamic therapy. The photophysical properties of porphyrins are highly influenced by their surrounding environment. Intermolecular interactions between these pigments can lead to excited state quenching, energy transfer and large changes to their absorption and fluorescence spectra. This thesis is focused on utilizing molecular self-assembly strategies to develop nanoscale porphyrin and phospholipid structures. The rationale being that intermolecular interactions between porphyrins in these nanostructures can induce changes which can be exploited in novel biomedical imaging and therapeutic applications. Four lipid-based structural platforms are studied including: nanoemulsions, bilayer discs and nanovesicles. In Chapter 1, I provide a background on the photophysics of porphyrins and the effect of intermolecular porphyrin interactions on photophysical properties. I also discuss phospholipids and their self-assembly process. Lastly I review current biomedical photonics techniques and discuss how these strategies can be used in conjugation with porphyrin and lipid supramolecular assemblies. In Chapter 2, I investigate the influence that loading a novel bacteriochlorin photosensitizer into a protein-stabilized lipid emulsion has on its spectral properties. I discovered that while the dye can be incorporated into the lipid emulsion, no changes were observed in its spectral properties. In Chapter 3, an amphipathic alpha-helical protein is used to stabilize and organize porphyrin-lipid molecules into bilayer discs. Close packing between porphyrin molecules causes quenching, which can be reversed by structural degradation of the

  8. Hybrid organic – silica nanomaterials based on novel A{sub 3}B mixed substituted porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Fagadar-Cosma, Eugenia [Institute of Chemistry -Timisoara of Romanian Academy, M. Viteazul Ave, No. 24, 300223 Timisoara (Romania); Dudás, Zoltán, E-mail: dudas.zoltan@wigner.mta.hu [Institute of Chemistry -Timisoara of Romanian Academy, M. Viteazul Ave, No. 24, 300223 Timisoara (Romania); MTA Wigner Research Center for Physics, Konkoly Thege Miklós Street, No. 29-33, 1121 Budapest (Hungary); Birdeanu, Mihaela [Institute of Chemistry -Timisoara of Romanian Academy, M. Viteazul Ave, No. 24, 300223 Timisoara (Romania); National Institute for Research and Development in Electrochemistry and Condensed Matter, 1 Plautius Andronescu Street, 300224 Timisoara (Romania); Almásy, László [MTA Wigner Research Center for Physics, Konkoly Thege Miklós Street, No. 29-33, 1121 Budapest (Hungary)

    2014-11-14

    A new A{sub 3}B porphyrin structure, namely: 5-(4-phenoxyphenyl)-10,15,20-tris(4-pyridyl)-porphyrin was synthetized and characterized by FT-IR, UV–vis, Fluorescence, MS, {sup 1}H NMR, TLC and HPLC. Novel hybrid-silica porphyrin nanomaterials were obtained by immobilizing the porphyrin in silica supports synthesized from tetraethoxysilane, tetramethoxysilane or mixtures of tetraethoxysilane/methyltriethoxysilane. Since the behavior and performance of immobilized porphyrin molecules in the silica matrices strongly depend on the structure of the porous network, a comparative characterization of the silica support and the hybrid porphyrin-silica materials was carried out using specific physicochemical characterization methods: UV–vis, Fluorencence, FT-IR spectroscopy, thermal analysis, AFM, nitrogen adsorption and small-angle neutron scattering. The UV–vis spectra show that no protonation and aggregation of porphyrin takes place in the gels made from methyltriethoxysilane precursor. Most of the emission spectra preserve both the shape and the intensity of the corresponding free porphyrin. Due to the lack of aggregation, when using the methyltriethoxysilane precursor, the quenching of fluorescence is also diminished. No matter of the preparation method the specific surface areas increase in the following order: TEOS < TMOS < TEOS/MTES 3:1 < TEOS/MTES 2:1 < TEOS/MTES 1:1. Due to their optical properties, both the novel porphyrin and its derived hybrid materials, especially those synthesized in situ with mixtures of silica precursors TEOS/MTES will be sent for further medical trials in PDT, having characteristics of second generation photosensitizers. Due to large specific surface areas, the same materials will be used as sensitive materials in microsensors for air quality control, to detect the presence of CO, NO{sub x}, excess of CO{sub 2} and low level of O{sub 2}. - Highlights: • Synthesis of new A{sub 3}B type porphyrin exhibiting high fluorescence

  9. A Perspective on the Trends and Challenges Facing Porphyrin-Based Anti-Microbial Materials.

    Science.gov (United States)

    Jiang, Lu; Gan, Ching Ruey Raymond; Gao, Jian; Loh, Xian Jun

    2016-07-01

    The emergence of multidrug resistant bacterium threatens to unravel global healthcare systems, built up over centuries of medical research and development. Current antibiotics have little resistance against this onslaught as bacterium strains can quickly evolve effective defense mechanisms. Fortunately, alternative therapies exist and, at the forefront of research lays the photodynamic inhibition approach mediated by porphyrin based photosensitizers. This review will focus on the development of various porphyrins compounds and their incorporation as small molecules, into polymers, fibers and thin films as practical therapeutic agents, utilizing photodynamic therapy to inhibit a wide spectrum of bacterium. The use of photodynamic therapy of these porphyrin molecules are discussed and evaluated according to their electronic and bulk material effect on different bacterium strains. This review also provides an insight into the general direction and challenges facing porphyrins and derivatives as full-fledged therapeutic agents and what needs to be further done in order to be bestowed their rightful and equal status in modern medicine, similar to the very first antibiotic; penicillin itself. It is hoped that, with this perspective, new paradigms and strategies in the application of porphyrins and derivatives will progressively flourish and lead to advances against disease. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A palladium label to monitor nanoparticle-assisted drug delivery of a photosensitizer into tumor spheroids by elemental bioimaging.

    Science.gov (United States)

    Niehoff, Ann-Christin; Moosmann, Aline; Söbbing, Judith; Wiehe, Arno; Mulac, Dennis; Wehe, Christoph A; Reifschneider, Olga; Blaske, Franziska; Wagner, Sylvia; Sperling, Michael; von Briesen, Hagen; Langer, Klaus; Karst, Uwe

    2014-01-01

    In this study, the cellular uptake of the second generation photosensitizer 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (mTHPP) was investigated using laser ablation coupled to inductively coupled plasma mass spectrometry (LA-ICP-MS) at a spatial resolution of 10 μm. To achieve high sensitivity, the photosensitizer was tagged with palladium. As a tumor model system, a 3D cell culture of the TKF-1 cell line was used. These tumor spheroids were incubated with the Pd-tagged photosensitizer embedded in poly(lactic-co-glycolic acid) (PLGA) nanoparticles to investigate the efficiency of nanoparticle based drug delivery. An accumulation of the drug in the first cell layers of the tumor spheroid was observed. In the case of nanoparticle based drug delivery, a significantly more homogeneous distribution of the photosensitizer was achieved, compared to tumor spheroids incubated with the dissolved photosensitizer without the nanoparticular drug delivery system. The infiltration depth of the Pd-tagged photosensitizer could not be increased with rising incubation time, which can be attributed to the adsorption of the photosensitizer onto cellular components.

  11. Boron reclamation

    International Nuclear Information System (INIS)

    Smith, R.M.

    1980-07-01

    A process to recover high purity 10 B enriched crystalline boron powder from a polymeric matrix was developed on a laboratory basis and ultimately scaled up to production capacity. The process is based on controlled pyrolysis of boron-filled scrap followed by an acid leach and dry sieving operation to return the powder to the required purity and particle size specifications. Typically, the recovery rate of the crystalline powder is in excess of 98.5 percent, and some of the remaining boron is recovered in the form of boric acid. The minimum purity requirement of the recovered product is 98.6 percent total boron

  12. Photosensitizer-Embedded Polyacrylonitrile Nanofibers as Antimicrobial Non-Woven Textile.

    Science.gov (United States)

    Stanley, Sarah L; Scholle, Frank; Zhu, Jiadeng; Lu, Yao; Zhang, Xiangwu; Situ, Xingci; Ghiladi, Reza A

    2016-04-20

    Toward the objective of developing platform technologies for anti-infective materials based upon photodynamic inactivation, we employed electrospinning to prepare a non-woven textile comprised of polyacrylonitrile nanofibers embedded with a porphyrin-based cationic photosensitizer; termed PAN-Por (+) . Photosensitizer loading was determined to be 34.8 nmol/mg material; with thermostability to 300 °C. Antibacterial efficacy was evaluated against four bacteria belonging to the ESKAPE family of pathogens ( Staphylococcus aureus ; vancomycin-resistant Enterococcus faecium ; Acinetobacter baumannii ; and Klebsiella pneumonia ), as well as Escherichia coli . Our results demonstrated broad photodynamic inactivation of all bacterial strains studied upon illumination (30 min; 65 ± 5 mW/cm²; 400-700 nm) by a minimum of 99.9996+% (5.8 log units) regardless of taxonomic classification. PAN-Por (+) also inactivated human adenovirus-5 (~99.8% reduction in PFU/mL) and vesicular stomatitis virus (>7 log units reduction in PFU/mL). When compared to cellulose-based materials employing this same photosensitizer; the higher levels of photodynamic inactivation achieved here with PAN-Por (+) are likely due to the combined effects of higher photosensitizer loading and a greater surface area imparted by the use of nanofibers. These results demonstrate the potential of photosensitizer-embedded polyacrylonitrile nanofibers to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action.

  13. Photosensitizer-Embedded Polyacrylonitrile Nanofibers as Antimicrobial Non-Woven Textile

    Science.gov (United States)

    Stanley, Sarah L.; Scholle, Frank; Zhu, Jiadeng; Lu, Yao; Zhang, Xiangwu; Situ, Xingci; Ghiladi, Reza A.

    2016-01-01

    Toward the objective of developing platform technologies for anti-infective materials based upon photodynamic inactivation, we employed electrospinning to prepare a non-woven textile comprised of polyacrylonitrile nanofibers embedded with a porphyrin-based cationic photosensitizer; termed PAN-Por(+). Photosensitizer loading was determined to be 34.8 nmol/mg material; with thermostability to 300 °C. Antibacterial efficacy was evaluated against four bacteria belonging to the ESKAPE family of pathogens (Staphylococcus aureus; vancomycin-resistant Enterococcus faecium; Acinetobacter baumannii; and Klebsiella pneumonia), as well as Escherichia coli. Our results demonstrated broad photodynamic inactivation of all bacterial strains studied upon illumination (30 min; 65 ± 5 mW/cm2; 400–700 nm) by a minimum of 99.9996+% (5.8 log units) regardless of taxonomic classification. PAN-Por(+) also inactivated human adenovirus-5 (~99.8% reduction in PFU/mL) and vesicular stomatitis virus (>7 log units reduction in PFU/mL). When compared to cellulose-based materials employing this same photosensitizer; the higher levels of photodynamic inactivation achieved here with PAN-Por(+) are likely due to the combined effects of higher photosensitizer loading and a greater surface area imparted by the use of nanofibers. These results demonstrate the potential of photosensitizer-embedded polyacrylonitrile nanofibers to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action. PMID:28335205

  14. Photosensitizer-Embedded Polyacrylonitrile Nanofibers as Antimicrobial Non-Woven Textile

    Directory of Open Access Journals (Sweden)

    Sarah L. Stanley

    2016-04-01

    Full Text Available Toward the objective of developing platform technologies for anti-infective materials based upon photodynamic inactivation, we employed electrospinning to prepare a non-woven textile comprised of polyacrylonitrile nanofibers embedded with a porphyrin-based cationic photosensitizer; termed PAN-Por(+. Photosensitizer loading was determined to be 34.8 nmol/mg material; with thermostability to 300 °C. Antibacterial efficacy was evaluated against four bacteria belonging to the ESKAPE family of pathogens (Staphylococcus aureus; vancomycin-resistant Enterococcus faecium; Acinetobacter baumannii; and Klebsiella pneumonia, as well as Escherichia coli. Our results demonstrated broad photodynamic inactivation of all bacterial strains studied upon illumination (30 min; 65 ± 5 mW/cm2; 400–700 nm by a minimum of 99.9996+% (5.8 log units regardless of taxonomic classification. PAN-Por(+ also inactivated human adenovirus-5 (~99.8% reduction in PFU/mL and vesicular stomatitis virus (>7 log units reduction in PFU/mL. When compared to cellulose-based materials employing this same photosensitizer; the higher levels of photodynamic inactivation achieved here with PAN-Por(+ are likely due to the combined effects of higher photosensitizer loading and a greater surface area imparted by the use of nanofibers. These results demonstrate the potential of photosensitizer-embedded polyacrylonitrile nanofibers to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action.

  15. The study of cellulosic fabrics impregnated with porphyrin compounds for use as photo-bactericidal polymers

    Energy Technology Data Exchange (ETDEWEB)

    Rahimi, Rahmatollah, E-mail: rahimi_rah@iust.ac.ir [Bioinorganic Chemistry Laboratory, Department of Chemistry, Iran University of Science and Technology, Tehran 16846-13114 (Iran, Islamic Republic of); Fayyaz, Fatemeh [Bioinorganic Chemistry Laboratory, Department of Chemistry, Iran University of Science and Technology, Tehran 16846-13114 (Iran, Islamic Republic of); Rassa, Mehdi [Department of Biology, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of)

    2016-02-01

    In the present work, we report on the preparation of cellulosic fabrics bearing two types of photo-sensitizers in order to prepare efficient polymeric materials for antimicrobial applications. The obtained porphyrin-grafted cellulosic fabrics were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, diffuse reflectance UV–Vis (DRUV) spectroscopy, thermo-gravimetric analysis (TG) and scanning electron microscopy (SEM). Antimicrobial activity of the prepared porphyrin-cellulose was tested under visible light irradiation against Staphylococcus aureus, Pseudomunas aeroginosa and Escherichia coli. In addition, the effect of two parameters on photo-bactericidal activity of treated fibers was studied: illumination time and concentration of photosensitizers (PS). - Highlights: • Cellulosic fabrics were impregnated with various concentrations of porphyrins (TAPP and its zinc ion complex). • The products were characterized by ATR-FTIR, DRUV, SEM and TG. • The photo-antibacterial activity of products was determined against S. aureus, P. aeroginosa and E. coli. • The effect of two parameters were studied on photoinactivation of treated fibers: illumination time and concentration of PS.

  16. Ocular Defects in Photosensitive Epilepsy

    Directory of Open Access Journals (Sweden)

    Ebere C. Anyanwu

    2004-01-01

    Full Text Available Patients with photosensitive epilepsy are susceptible to seizures due to photoparoxysmal response (PPR. This response adversely precipitates factors that modify the functional status of the visual system. Such factors may or may not be evident superficially, but may lead to ocular defects due to trauma, hormonal imbalance, abnormal intraocular pressure (IOP, or any other reflex-inducing stimuli. The extent to which photosensitive epileptic patients suffer from PPR-related ocular defects has not been documented fully. In this investigation, ocular defects in patients with photosensitive epilepsy are studied using visual-evoked response (VER. A total of 212 photosensitive epileptic patients were studied to ascertain the magnitude and distribution of ocular defects using the changes in EEG and visual-evoked potential (VEP; 51% of the patients were female, the age range was 1–46 years. The major ocular defects and complications found were visual field defects, optic nerve abnormalities, nystagmus, cataracts, amblyopia, and migraine. These findings were analyzed according to age and sex. The relationship between the ocular abnormalities and the interpretations of the changes in the characteristics of the VEP indicated that optic-related atrophies, visual defects, optic neuritis, chiasmal compression, nystagmus, migraine headache, cataracts, and amblyopia were prevalent in photosensitive epileptic patients at varying degrees. The results showed that although ocular defects in photosensitive epilepsy may not be obvious differentially, VEP can be used in their diagnosis, contrary to earlier studies reporting that VEP is not of much value in epilepsy diagnosis.

  17. Porphyrin mediated photo-modification of the structure and function of human serum albumin

    Science.gov (United States)

    Rozinek, Sarah C.

    Photosensitization reactions involve irradiating (with visible light) molecules with a high efficiency for either electron transfer or entering an excited triplet state (photosensitizer). Such reactions are applied to photodynamic cancer therapy, many medical laser-treatments, and a potential array of disinfection and pest elimination techniques. To understand the biophysical mechanisms of how these applications are effective at the protein level, the group of Dr. Brancaleon (UTSA) has investigated the irradiation of several dye-protein combinations, and discovered effects on protein structure and function. To further that work, we have investigated irradiation of the protein, human serum albumin (HSA), photosensitized by either protoporphyrin IX (PPIX) or meso-tetrakis(4-sulfonatophenyl)porphyrin (TSPP). HSA is the most abundant plasma protein, making it a likely substrate in PDT, and it possesses a specific binding pocket for iron-PPIX (heme) and possibly other porphyrin derivatives. The results of our research are summarized as follows. First, a thorough characterization of the binding of each photosensitizer to albumin was completed, elucidating a probable binding location for TSPP. Next, fluorescence lifetime emission of the single tryptophan residue, alongside circular dichroism, found tertiary structural changes around tryptophan and an overall 20% decrease in protein secondary structure after irradiation with TSPP bound. Finally, to determine if protein function was lost after photosensitization, size exclusion chromatography found modified albumin still recognizable by its receptor-protein, and comparative ex vivo up-take studies revealed that modified albumin is not processed the same way as native albumin in live tapeworm larva (Mesocestoides corti). Thus we found that visible light can induce partial unfolding of a protein by using a photo-activated ligand. These small structural modifications were sufficient to affect the protein's biological function.

  18. A metal-lustrous porphyrin foil.

    Science.gov (United States)

    Morisue, Mitsuhiko; Hoshino, Yuki; Shimizu, Masaki; Tomita, Shogo; Sasaki, Sono; Sakurai, Shinichi; Hikima, Takaaki; Kawamura, Ayaka; Kohri, Michinari; Matsui, Jun; Yamao, Takeshi

    2017-09-26

    A metal-lustrous self-standing film, named "porphyrin foil", was formed from a glass-forming polymeric porphyrin. The amorphous glass nature of the porphyrin foil played a key role in spontaneously producing a smooth surface. Its sharp contrast in intense absorption and specular reflection of light at each wavelength provided a brilliant metallic lustre.

  19. Synthesis and photobactericidal properties of a neutral porphyrin grafted onto lignocellulosic fibers

    Energy Technology Data Exchange (ETDEWEB)

    Nzambe Ta keki, Jean Kerim; Ouk, Tan-Sothéa [Laboratoire de chimie des substances naturelles, Université de Limoges, 123 avenue Albert Thomas, 87060 Limoges (France); Zerrouki, Rachida [Laboratoire de chimie des substances naturelles, Université de Limoges, 123 avenue Albert Thomas, 87060 Limoges (France); Centre de Recherche sur les Matériaux Lignocellulosiques, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7 (Canada); Faugeras, Pierre-Antoine; Sol, Vincent [Laboratoire de chimie des substances naturelles, Université de Limoges, 123 avenue Albert Thomas, 87060 Limoges (France); Brouillette, François [Centre de Recherche sur les Matériaux Lignocellulosiques, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7 (Canada)

    2016-05-01

    Photodynamic antimicrobial chemotherapy (PACT), as one of the promising alternative antimicrobial treatment, has received great attention in recent years. In this work, a new antimicrobial material has been elaborated by grafting a neutral porphyrin, the metallated 5-(4-azidophenyl)-10,15,20-triphenylporphyrin, onto lignocellulosic fibers by using the Copper (I)-Catalyzed Alkyne-Azide 1,3-dipolar Cycloaddition (CuAAC) reaction. The cross-linked porphyrin-Kraft pulp material was characterized by infrared and by XPS spectroscopy analyses, which proved the covalent linkage between the porphyrin and propargylated Kraft pulp fibers. The antimicrobial activity of this material was tested under visible light irradiation with a low light dose (9.5 J/cm{sup 2}) against Staphylococcus aureus and Pseudomonas aeruginosa. The two bacterial strains deposited on the resulting photosensitizing Kraft pulp are efficiently killed after illumination. Such materials could find applications in industrial, household and medical environments as an alternative to overcome the widespread microbial multiresistance to classical treatments. - Highlights: • Elaboration of new antimicrobial paper • Grafting of porphyrin on lignocellulosic fibers using click chemistry • Modification of Kraft pulp fibers, using water as solvent.

  20. Porphyrins Fused with Unactivated Polycyclic Aromatic Hydrocarbons

    KAUST Repository

    Diev, Vyacheslav V.

    2012-01-06

    A systematic study of the preparation of porphyrins with extended conjugation by meso,β-fusion with polycyclic aromatic hydrocarbons (PAHs) is reported. The meso-positions of 5,15-unsubstituted porphyrins were readily functionalized with PAHs. Ring fusion using standard Scholl reaction conditions (FeCl 3, dichloromethane) occurs for perylene-substituted porphyrins to give a porphyrin β,meso annulated with perylene rings (0.7:1 ratio of syn and anti isomers). The naphthalene, pyrene, and coronene derivatives do not react under Scholl conditions but are fused using thermal cyclodehydrogenation at high temperatures, giving mixtures of syn and anti isomers of the meso,β-fused porphyrins. For pyrenyl-substituted porphyrins, a thermal method gives synthetically acceptable yields (>30%). Absorption spectra of the fused porphyrins undergo a progressive bathochromic shift in a series of naphthyl (λ max = 730 nm), coronenyl (λ max = 780 nm), pyrenyl (λ max = 815 nm), and perylenyl (λ max = 900 nm) annulated porphyrins. Despite being conjugated with unsubstituted fused PAHs, the β,meso-fused porphyrins are more soluble and processable than the parent nonfused precursors. Pyrenyl-fused porphyrins exhibit strong fluorescence in the near-infrared (NIR) spectral region, with a progressive improvement in luminescent efficiency (up to 13% with λ max = 829 nm) with increasing degree of fusion. Fused pyrenyl-porphyrins have been used as broadband absorption donor materials in photovoltaic cells, leading to devices that show comparatively high photovoltaic efficiencies. © 2011 American Chemical Society.

  1. Photosensitive Epilepsy In Kashmir Valley

    Directory of Open Access Journals (Sweden)

    Saleem S M

    2003-01-01

    Full Text Available A random population of 618 people with epilepsy hailing from different parts of Kashmir valley was screened for photosensitivity both clinically and on a standard protocol of intermittent photic stimulation (IPS provoked EEG recordings. Six (0.9% patients with a mean age of 15+6.57 years were found to be photosensitive; five had generalized and one had absence seizures. The baseline EEG in all patients showed generalized epileptiform discharges. On IPS, similar EEG findings were obtained with a narrow range of stimulus frequency i.e. 7-12 cycles/sec. There appears to be a low prevalence of photo-sensitivity in our epileptic population, possibly related to genetic factors.

  2. Validation of quantitative structure-activity relationship (QSAR) model for photosensitizer activity prediction.

    Science.gov (United States)

    Frimayanti, Neni; Yam, Mun Li; Lee, Hong Boon; Othman, Rozana; Zain, Sharifuddin M; Rahman, Noorsaadah Abd

    2011-01-01

    Photodynamic therapy is a relatively new treatment method for cancer which utilizes a combination of oxygen, a photosensitizer and light to generate reactive singlet oxygen that eradicates tumors via direct cell-killing, vasculature damage and engagement of the immune system. Most of photosensitizers that are in clinical and pre-clinical assessments, or those that are already approved for clinical use, are mainly based on cyclic tetrapyrroles. In an attempt to discover new effective photosensitizers, we report the use of the quantitative structure-activity relationship (QSAR) method to develop a model that could correlate the structural features of cyclic tetrapyrrole-based compounds with their photodynamic therapy (PDT) activity. In this study, a set of 36 porphyrin derivatives was used in the model development where 24 of these compounds were in the training set and the remaining 12 compounds were in the test set. The development of the QSAR model involved the use of the multiple linear regression analysis (MLRA) method. Based on the method, r(2) value, r(2) (CV) value and r(2) prediction value of 0.87, 0.71 and 0.70 were obtained. The QSAR model was also employed to predict the experimental compounds in an external test set. This external test set comprises 20 porphyrin-based compounds with experimental IC(50) values ranging from 0.39 μM to 7.04 μM. Thus the model showed good correlative and predictive ability, with a predictive correlation coefficient (r(2) prediction for external test set) of 0.52. The developed QSAR model was used to discover some compounds as new lead photosensitizers from this external test set.

  3. Validation of Quantitative Structure-Activity Relationship (QSAR) Model for Photosensitizer Activity Prediction

    Science.gov (United States)

    Frimayanti, Neni; Yam, Mun Li; Lee, Hong Boon; Othman, Rozana; Zain, Sharifuddin M.; Rahman, Noorsaadah Abd.

    2011-01-01

    Photodynamic therapy is a relatively new treatment method for cancer which utilizes a combination of oxygen, a photosensitizer and light to generate reactive singlet oxygen that eradicates tumors via direct cell-killing, vasculature damage and engagement of the immune system. Most of photosensitizers that are in clinical and pre-clinical assessments, or those that are already approved for clinical use, are mainly based on cyclic tetrapyrroles. In an attempt to discover new effective photosensitizers, we report the use of the quantitative structure-activity relationship (QSAR) method to develop a model that could correlate the structural features of cyclic tetrapyrrole-based compounds with their photodynamic therapy (PDT) activity. In this study, a set of 36 porphyrin derivatives was used in the model development where 24 of these compounds were in the training set and the remaining 12 compounds were in the test set. The development of the QSAR model involved the use of the multiple linear regression analysis (MLRA) method. Based on the method, r2 value, r2 (CV) value and r2 prediction value of 0.87, 0.71 and 0.70 were obtained. The QSAR model was also employed to predict the experimental compounds in an external test set. This external test set comprises 20 porphyrin-based compounds with experimental IC50 values ranging from 0.39 μM to 7.04 μM. Thus the model showed good correlative and predictive ability, with a predictive correlation coefficient (r2 prediction for external test set) of 0.52. The developed QSAR model was used to discover some compounds as new lead photosensitizers from this external test set. PMID:22272096

  4. Probing Photosensitization by Functionalized Carbon Nanotubes

    Science.gov (United States)

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  5. A Closer Look at Dark Toxicity of the Photosensitizer TMPyP in Bacteria.

    Science.gov (United States)

    Eckl, Daniel B; Dengler, Linda; Nemmert, Marina; Eichner, Anja; Bäumler, Wolfgang; Huber, Harald

    2018-01-01

    Photodynamic inactivation of bacteria (PIB) is based on photosensitizers which absorb light and generate reactive oxygen species (ROS), killing cells via oxidation. PIB is evaluated by comparing viability with and without irradiation, where reduction of viability in the presence of the photosensitizer without irradiation is considered as dark toxicity. This effect is controversially discussed for photosensitizers like TMPyP (5,10,15,20-Tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluensulfonate). TMPyP shows a high absorption coefficient for blue light and a high yield of ROS production, especially singlet oxygen. Escherichia coli and Bacillus atrophaeus were incubated with TMPyP and irradiated with different light sources at low radiant exposures (μW per cm²), reflecting laboratory conditions of dark toxicity evaluation. Inactivation of E. coli occurs for blue light, while no effect was detectable for wavelengths >450 nm. Being more susceptible toward PIB, growth of B. atrophaeus is even reduced for light with emission >450 nm. Decreasing the light intensities to nW per cm² for B. atrophaeus, application of TMPyP still caused bacterial killing. Toxic effects of TMPyP disappeared after addition of histidine, quenching residual ROS. Our experiments demonstrate that the evaluation of dark toxicity of a powerful photosensitizer like TMPyP requires low light intensities and if necessary additional application of substances quenching any residual ROS. © 2017 The American Society of Photobiology.

  6. Crystalline boron nitride aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

    2017-12-12

    This disclosure provides methods and materials related to boron nitride aerogels. For example, one aspect relates to a method for making an aerogel comprising boron nitride, comprising: (a) providing boron oxide and an aerogel comprising carbon; (b) heating the boron oxide to melt the boron oxide and heating the aerogel; (c) mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide; and (d) converting at least a portion of the carbon to boron nitride to obtain the aerogel comprising boron nitride. Another aspect relates to a method for making an aerogel comprising boron nitride, comprising heating boron oxide and an aerogel comprising carbon under flow of a nitrogen-containing gas, wherein boron oxide vapor and the nitrogen-containing gas convert at least a portion of the carbon to boron nitride to obtain the aerogel comprising boron nitride.

  7. Radiation carcinogenesis: radioprotectors and photosensitizers

    International Nuclear Information System (INIS)

    Fry, R.J.M.

    1982-01-01

    This paper outlines 1) some of the salient features of radiation carcinogenesis that are pertinent to the questions of how the carcinogenic effects might be influenced, 2) the effects of radioprotectors on ionizing radiation-induced cancer, and 3) the effect of photosensitizers on UVR-induced skin cancer

  8. Radiation carcinogenesis: radioprotectors and photosensitizers

    Energy Technology Data Exchange (ETDEWEB)

    Fry, R.J.M.

    1982-01-01

    This paper outlines 1) some of the salient features of radiation carcinogenesis that are pertinent to the questions of how the carcinogenic effects might be influenced, 2) the effects of radioprotectors on ionizing radiation-induced cancer, and 3) the effect of photosensitizers on UVR-induced skin cancer.

  9. Porphyrins and Metalloporphyrins: Potential Hypoxic Agents

    OpenAIRE

    James, B. R.; Meng, G. G.; Posakony, J. J.; Ravensbergen, J. A.; Ware, C. J.; Skov, K. A.

    1996-01-01

    Synthetic water-soluble porphyrins and their metalloporphyrin derivatives with Co(III), Cu(II), Ru(II) and Pt(II), containing various functional groups within the meso-positions of the porphyrin, were synthesised and evaluated as hypoxic agents, especially as cytotoxins and radiosensitisers. Cobalt complexes of the porphyrins containing positively charged methylpyridinium groups showed selective toxicity toward hypoxic Chinese Hamster Ovary (CHO) cells. The Co(III) complexes of the cationic a...

  10. A genetically targetable near-infrared photosensitizer.

    Science.gov (United States)

    He, Jianjun; Wang, Yi; Missinato, Maria A; Onuoha, Ezenwa; Perkins, Lydia A; Watkins, Simon C; St Croix, Claudette M; Tsang, Michael; Bruchez, Marcel P

    2016-03-01

    Upon illumination, photosensitizer molecules produce reactive oxygen species that can be used for functional manipulation of living cells, including protein inactivation, targeted-damage introduction and cellular ablation. Photosensitizers used to date have been either exogenous, resulting in delivery and removal challenges, or genetically encoded proteins that form or bind a native photosensitizing molecule, resulting in a constitutively active photosensitizer inside the cell. We describe a genetically encoded fluorogen-activating protein (FAP) that binds a heavy atom-substituted fluorogenic dye, forming an 'on-demand' activated photosensitizer that produces singlet oxygen and fluorescence when activated with near-infrared light. This targeted and activated photosensitizer (TAPs) approach enables protein inactivation, targeted cell killing and rapid targeted lineage ablation in living larval and adult zebrafish. The near-infrared excitation and emission of this FAP-TAPs provides a new spectral range for photosensitizer proteins that could be useful for imaging, manipulation and cellular ablation deep within living organisms.

  11. Porphyrin coordination polymer nanospheres and nanorods

    Science.gov (United States)

    Wang, Zhongchun; Shelnutt, John A.; Medforth, Craig J.

    2012-12-04

    A porphyrin coordination polymer nanostructure comprising a network of pyridyl porphyrin molecules and coordinating metal ions coordinatively bound through the pyridyl groups. In some embodiments, the porphyrins are metalloporphyrins. A variety of nanostructures are formed by the network polymer, including nanospheres, polygonal nanostructures, nanorods, and nanofibers, depending on a variety of factors including coordination metal ion, porphyrin type, metal of the metalloporphyrin, and degree of agitation during nanostructure formation. Reduction of coordinating metal ions may be used to form metal nanoparticles on the coordination polymer nanostructure.

  12. High content screening as high quality assay for biological evaluation of photosensitizers in vitro.

    Directory of Open Access Journals (Sweden)

    Gisela M F Vaz

    Full Text Available A novel single step assay approach to screen a library of photdynamic therapy (PDT compounds was developed. Utilizing high content analysis (HCA technologies several robust cellular parameters were identified, which can be used to determine the phototoxic effects of porphyrin compounds which have been developed as potential anticancer agents directed against esophageal carcinoma. To demonstrate the proof of principle of this approach a small detailed study on five porphyrin based compounds was performed utilizing two relevant esophageal cancer cell lines (OE21 and SKGT-4. The measurable outputs from these early studies were then evaluated by performing a pilot screen using a set of 22 compounds. These data were evaluated and validated by performing comparative studies using a traditional colorimetric assay (MTT. The studies demonstrated that the HCS assay offers significant advantages over and above the currently used methods (directly related to the intracellular presence of the compounds by analysis of their integrated intensity and area within the cells. A high correlation was found between the high content screening (HCS and MTT data. However, the HCS approach provides additional information that allows a better understanding of the behavior of these compounds when interacting at the cellular level. This is the first step towards an automated high-throughput screening of photosensitizer drug candidates and the beginnings of an integrated and comprehensive quantitative structure action relationship (QSAR study for photosensitizer libraries.

  13. Effects of a novel photoactivated photosensitizer on MDR1 over-expressing human breast cancer cells.

    Science.gov (United States)

    Chen, Jing-Jing; Liu, Shu-Ping; Zhao, Jun; Wang, Si-Cheng; Liu, Tian-Jun; Li, Xiang

    2017-06-01

    Multidrug resistance (MDR) was the main reason of cancer chemotherapy failure. Photodynamic therapy (PDT) has been applied to the treatment of tumor and considered as a strategy for the overcoming of MDR phenomenon. Present study focused on a novel porphyrin-based photosensitizer DTP (meso-5-[p-diethylene triamine pentaacetic acid-aminophenyl]-10,15,20-triphenyl-porphyrin)-mediated photocytotoxicity on MDR1 highly expressing human breast cancer cell line MCF-7/ADR (adriamycin resistant) and the parental MCF-7 cell line. Experimental results indicated that DTP-PDT induced significant photocytotoxicity on MDR1 highly expressing MCF-7/ADR cell line, in spite of slightly weaker than on MCF-7 cell line, which was due to the relatively lower level of intracellular DTP in resistant MCF-7/ADR cells. Furthermore, intracellular DTP level in resistant MCF-7/ADR cells could not be altered with a Pgp inhibitor, verapamil and this indicated that DTP was not a possible substrate for the multidrug transporter Pgp. More importantly, photoactivated DTP could significantly reduce the expression of MDR1 gene at all the levels of mRNA, protein and function. The combined treatment with DTP-PDT and adriamycin was found to be more effective than adriamycin or DTP-PDT alone. In conclusion, our data demonstrated that DTP probably will be a potential photosensitizer in combating MDR phenomenon during the treatment of human breast cancer. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Effect of Pluronic F-127 on the photosensitizing activity of tetraphenylporphyrins in organic and aqueous phases

    Science.gov (United States)

    Savko, M. A.; Aksenova, N. A.; Akishina, A. K.; Khasanova, O. V.; Glagolev, N. N.; Rumyantseva, V. D.; Zhdanova, K. A.; Spokoinyi, A. L.; Solov'eva, A. B.

    2017-11-01

    The solubilization of hydrophobic porphyrin photosensitizers (PPSes) to obtain corresponding water-soluble forms is an important line of modern antimicrobial photodynamic therapy. It is shown that a triblock copolymer of ethylene and propylene oxides, Pluronic F-127, one of the most nontoxic and effective polymer surface active substances (SASes), can be used for the conversion of hydrophobic tetraphenylporphyrin (TPP) and monosubstituted and tetrasubstituted hydroxy, amino, and nitro TPPs into water-soluble forms. It is found that Pluronic has a substantially higher solubilizing affinity (defined as the minimum molar concentration of an SAS required for the complete migration of porphyrin with a specific molar concentration to the aqueous phase) toward monosubstituted TPPs than to corresponding tetrasubstituted porphyrins. It is shown that with Pluronic in the organic phase, the activity of tetraphenylporphyrin in a test reaction of the oxidation of anthracene is higher than that of its monosubstituted and tetrasubstituted derivatives. In an aqueous medium, the activity of solubilized mono derivatives of TPP is comparable to that of unsubstituted TPP and is higher than the activity of the corresponding tetra derivatives of TPP.

  15. Photosensitized oxidation of unsaturated polymers

    Science.gov (United States)

    Golub, M. A.

    1979-01-01

    The photosensitized oxidation or singlet oxygenation of unsaturated hydrocarbon polymers and of their model compounds was reviewed. Emphasis was on cis and trans forms of 1,4-polyisoprene, 1,4-polybutadiene and 1,2-poly(1,4-hexadiene), and on 1,4-poly(2,3-dimethyl-1,3-butadiene). The microstructural changes which occur in these polymers on reaction with O2-1 in solution were investigated by infrared H-1 and C-13 NMR spectroscopy. The polymers were shown to yield allylic hydroperoxides with shifted double bonds according to the ene mechanism established for simple olefins. The photosensitized oxidation of the above unsaturated polymer exhibited zero order kinetics, the relative rates paralleling the reactivities of the corresponding simple olefins towards O2-1.

  16. LDL Receptors as Gateways for Intracellular Porphyrin Uptake

    International Nuclear Information System (INIS)

    Novick, S.; Laster, B.; Quastel, M.

    2004-01-01

    Boronated compounds are currently being studied for possible use in Boron Neutron Capture Therapy (BNCT). We found that one of these agents, BOPP (tetrakis-carborane-carboxylate, esters of 2,4-bis (a,b- dihydroxyethyl) deuteroporphyrin IX), could also be labeled with indium (In-BOPP) and, therefore, could also be used potentially to transport high Z atoms into tumor cell DNA for AET (Auger Electron Therapy). In order to assess the uptake of these agents into cells, the role of the LDL receptor in the intracellular accumulation of BOPP and In-BOPP was investigated. Pre-incubation of V-79 Chinese hamster cells in medium containing delipidized fetal bovine serum (FBS) markedly increased the subsequent uptake of intracellular boron transported by both BOPP and In-BOPP when compared with cells that had been pre-incubated with medium containing 10% normal FBS (lipidized). The increased uptake was characterized by elevated levels of receptor, and greater affinity was shown for both BOPP and In-BOPP, although less marked with the latter. Positive cooperativity was demonstrated by sigmoid saturation curves, Scatchard analysis and Hill plots. Increasing the amount of LDL in the incubation medium had a relatively small effect on the total accumulation of either indium or boron atoms inside the cell. Furthermore, chemical acetylation of LDL did not decrease the intracellular uptake of either boron or indium transported by BOPP or In-BOPP. It is thus concluded that BOPP and In-BOPP preferentially enter the cells directly by way of the LDL receptor and that only a small fraction of these molecules are transported into the cells indirectly using serum LDLs as their carriers. These data suggest a novel way of bringing greater amounts of boron and indium (and perhaps other agents) into tissues. Porphyrins can be used to transport different agents into tumor cells because they are tumor affinic molecules. Tumors express a higher number of LDL receptors than do most normal tissues

  17. Preparation and characterization of monosubstituted porphyrins ...

    Indian Academy of Sciences (India)

    The exclusion of the aforementioned side products during the synthesis of monosubstituted porphyrins greatly reduced the complexity during purification of the product. Absorption spectrophotometry was performed on silica gel immobilizing porphyrin (CPTTP), free base tetraphenylporphyrin (H2TPP) and heteroaldehydes ...

  18. Ligations of Gold Atoms with Iron Porphyrin

    DEFF Research Database (Denmark)

    Zhang, Ling; Kepp, Kasper Planeta; Ulstrup, Jens

    electrochemistry and electrochemical scanning tunneling microscopy (in situ STM) are explained with this theory. Iron porphyrin is a well-known active redox center of cytochrome c and hemoglobin/myoglobin assisting membrane-crossing electron transfer or blood oxygentransport. The electronic states...... and configurations of iron porphyrin affect the electrochemical properties of the metalloproteins, where the artificial constructed proteins are designed by the mutations of amino residues or the structural optimizations of iron porphyrins. Iron porphyrin adsorption on graphite and graphene surfaces by п-п electron...... stacking has been widely studied and the catalytic activity found to be enhanced warranting the notion of enzyme mimics. Weak physisorption was, however, recently observed by in situ STM, but the electronic properties of iron porphyrin adsorbed on gold has not been addressed before. This issue is, however...

  19. Visible light-driven O2 reduction by a porphyrin-laccase system.

    Science.gov (United States)

    Lazarides, Theodore; Sazanovich, Igor V; Simaan, A Jalila; Kafentzi, Maria Chrisanthi; Delor, Milan; Mekmouche, Yasmina; Faure, Bruno; Réglier, Marius; Weinstein, Julia A; Coutsolelos, Athanassios G; Tron, Thierry

    2013-02-27

    Several recent studies have shown that the combination of photosensitizers with metalloenzymes can support a light-driven multielectron reduction of molecules such as CO(2) or HCN. Here we show that the association of the zinc tetramethylpyridinium porphyrin (ZnTMPyP(4+)) photosensitizer with the multicopper oxidase (MCO) laccase allows to link the oxidation of an organic molecule to the four electrons reduction of dioxygen into water. The enzyme is photoreduced within minutes with porphyrin/enzyme ratio as low as 1:40. With a 1:1 ratio, the dioxygen consumption rate is 1.7 μmol L(-1) s(-1). Flash photolysis experiments support the formation of the triplet excited state of ZnTMPyP(4+) which reduces the enzyme to form a radical cation of the porphyrin with a k(ET) ≈ 10(7) s(-1) M(-1). The long-lived triplet excited state of the ZnTMPyP(4+) (τ(0) = 0.72 ms) accounts for a substantial electron-transfer quantum yield, φ(ET) = 0.35. Consequently, the enzyme-dependent photo-oxidation of the electron donor occurs with a turnover of 8 min(-1) for the one-electron oxidation process, thereby supporting the suitability of such enzyme/sensitizer hybrid systems for aerobic photodriven transformations on substrates. This study is the first example of a phorphyrin-sensitized four-electron reduction of an enzyme of the MCO family, leading to photoreduction of dioxygen into water.

  20. Energy and electron transfers in photosensitive chitosan.

    Science.gov (United States)

    Wu, Shuizhu; Zeng, Fang; Zhu, Hongping; Tong, Zhen

    2005-02-23

    Novel photosensitive chitosan was synthesized. The modified chitosan contains photoactive anthracene chromophore moieties. Because of the presence of anthracene chromophores, the polymer absorbs light in the UV-vis spectral region. Electronically excited polymeric chromophores could participate in energy and electron transfer processes to the suitable acceptor molecules. The photosensitive chitosan developed herein could could act as an efficient photosensitizer and lead to the application of the environmentally friendly photocatalytic system for an efficient degradation of a wide range of pollutants.

  1. Fabrication of self-written waveguide in photosensitive polyimide resin by controlling photochemical reaction of photosensitizer

    International Nuclear Information System (INIS)

    Yamashita, K.; Kuro, T.; Oe, K.; Mune, K.; Tagawa, K.; Naitou, R.; Mochizuki, A.

    2004-01-01

    We have investigated optical properties of photosensitive polyimide appropriating for long self-written waveguide fabrication. From systematic measurements of absorption properties, it was found that photochemical reaction of photosensitizer dissolved in the photosensitive polyimide resins relates to transparency after the exposure, which limits the length of the fabricated self-written waveguide. By controlling the photochemical reaction, in which the photosensitive polyimide resin has sufficient transparency during exposure, four times longer self-written waveguide core was fabricated

  2. Porphyrin-Based Photocatalytic Lithography

    Energy Technology Data Exchange (ETDEWEB)

    Bearinger, J; Stone, G; Christian, A; Dugan, L; Hiddessen, A; Wu, K J; Wu, L; Hamilton, J; Stockton, C; Hubbell, J

    2007-10-15

    Photocatalytic lithography is an emerging technique that couples light with coated mask materials in order to pattern surface chemistry. We excite porphyrins to create radical species that photocatalytically oxidize, and thereby pattern, chemistries in the local vicinity. The technique advantageously does not necessitate mass transport or specified substrates, it is fast and robust and the wavelength of light does not limit the resolution of patterned features. We have patterned proteins and cells in order to demonstrate the utility of photocatalytic lithography in life science applications.

  3. Porphyrin-based Photocatalytic Nanolithography

    Energy Technology Data Exchange (ETDEWEB)

    Bearinger, J P; Stone, G; Dugan, L C; Dasher, B E; Stockton, C; Conway, J W; Kuenzler, T; Hubbell, J A

    2009-06-08

    Nanoarray fabrication is a multidisciplinary endeavor encompassing materials science, chemical engineering and biology. We form nanoarrays via a new technique, porphyrin-based photocatalytic nanolithography (PCNL). The nanoarrays, with controlled features as small as 200 nm, exhibit regularly ordered patterns and may be appropriate for (a) rapid and parallel proteomic screening of immobilized biomolecules, (b) protein-protein interactions and/or (c) biophysical and molecular biology studies involving spatially dictated ligand placement. We demonstrate protein immobilization utilizing nanoarrays fabricated via PCNL on silicon substrates, where the immobilized proteins are surrounded by a non-fouling polymer background.

  4. Porphyrins and metalloporphyrins: potential hypoxic agents.

    Science.gov (United States)

    James, B R; Meng, G G; Posakony, J J; Ravensbergen, J A; Ware, C J; Skov, K A

    1996-01-01

    Synthetic water-soluble porphyrins and their metalloporphyrin derivatives with Co(III), Cu(II), Ru(II) and Pt(II), containing various functional groups within the meso-positions of the porphyrin, were synthesised and evaluated as hypoxic agents, especially as cytotoxins and radiosensitisers. Cobalt complexes of the porphyrins containing positively charged methylpyridinium groups showed selective toxicity toward hypoxic Chinese Hamster Ovary (CHO) cells. The Co(III) complexes of the cationic and the anionic porphyrins are all weak radiosensitisers toward hypoxic cells, the highest sensitisation enhancement ratio (SER = 1.22, at 50 muM) being with a porphyrin complex containing a cis-arrangement of two nitro and two methylpyridinium meso-substituents. A copper complex of a tetracationic porphyrin showed slight radiosensitisation activity with an SER value of about 1.1. The other metalloporphyrins showed no hypoxic selectivity or radiosensitisation activity. In total, over 50 porphyrin free bases have been synthesised, of which half are water-soluble and have been metallated; thus, the chemistry is now in place for further development of water-soluble hypoxic agents.

  5. Supramolecular macrocycles based on porphyrins- correlation of molecular structure and biological photoactivity

    International Nuclear Information System (INIS)

    Ion, R. M.; Oprea, F.; Bacinschi, Z.; Scarlat, F.; Scarlat, Fl.; Niculescu, V.I.R.

    2002-01-01

    Porphyrins and phthalocyanines are organic dyes which can be used as highly fluorescent species in laser technology, in photography, as radiation power indicators, as photosensitizers in photodynamic therapy of cancerous disease. Porphyrins constitute a class of the molecules which contain four pyrrole rings linked by the methane carbon bridges whereas the phthalocyanine molecules are composed of four indole units - pyrrole rings linked by nitrogen atoms conjugated with benzene rings. A large group of porphyrins and phthalocyanines can be chemically modified by introducing metal in the center of the pyrrole rings or by attaching the peripheral groups to the outer rings of the methane bridges or isoindole units, respectively. In this study five groups of tetraphenylporphyrins (TPP) and phthalocyanines (Pc) were investigated: - metal (Me)-free dyes without any substitutes, - non-substituted porphyrins and phthalocyanines but complexed with metal (Me) - Zn, Mg, Mn, Co, Cu, Pt, Pd, Pb and others, - metal-complexed dyes substituted with aromatic rings, - metal-complexed dyes substituted with fluorines, - metal-complexed dyes substituted with long organic chains (alkyl or alkyloxy). The difference in the TPP and Pc molecular structure, the kind of metal incorporated into the main molecular core or the variation in the peripheral groups attached to the molecular skeleton are expected to affect the effectiveness of dyes in photocurrent generation. Since there is a competition between the charge separation process and other deactivation processes in the molecule, in our study photochemical investigations (photodynamic action) are usually accompanied with the spectroscopic examinations (absorption, fluorescence- which give information on the (non-) radiative processes) of dyes. In the paper we have presented the review of our study on the correlation between the molecular structure of dyes and their photoactive properties. (authors)

  6. Crystal engineering of porphyrin framework solids.

    Science.gov (United States)

    Goldberg, Israel

    2005-03-14

    This article describes recent achievements made by us and other groups in targeted synthesis of porphyrin-based framework solids by various non-covalent mechanisms of molecular recognition. The self-assembly processes are effected in a tunable manner either by direct association of suitably designed porphyrin building blocks, or by their supramolecular aggregation through external linkers as metal ions and organic bi-dentate ligands. Many of these crystalline porphyrin materials exhibit open architectures and remarkable structural integrity, and their potential application for selective guest storage and molecular sieving is highlighted.

  7. Boron nitride composites

    Science.gov (United States)

    Kuntz, Joshua D.; Ellsworth, German F.; Swenson, Fritz J.; Allen, Patrick G.

    2017-02-21

    According to one embodiment, a composite product includes: a matrix material including hexagonal boron nitride and one or more borate binders; and a plurality of cubic boron nitride particles dispersed in the matrix material. According to another embodiment, a composite product includes: a matrix material including hexagonal boron nitride and amorphous boron nitride; and a plurality of cubic boron nitride particles dispersed in the matrix material.

  8. Boron Nitride Nanotubes

    Science.gov (United States)

    Smith, Michael W. (Inventor); Jordan, Kevin (Inventor); Park, Cheol (Inventor)

    2012-01-01

    Boron nitride nanotubes are prepared by a process which includes: (a) creating a source of boron vapor; (b) mixing the boron vapor with nitrogen gas so that a mixture of boron vapor and nitrogen gas is present at a nucleation site, which is a surface, the nitrogen gas being provided at a pressure elevated above atmospheric, e.g., from greater than about 2 atmospheres up to about 250 atmospheres; and (c) harvesting boron nitride nanotubes, which are formed at the nucleation site.

  9. Porphyrin-Based Nanostructures for Photocatalytic Applications

    Directory of Open Access Journals (Sweden)

    Yingzhi Chen

    2016-03-01

    Full Text Available Well-defined organic nanostructures with controllable size and morphology are increasingly exploited in optoelectronic devices. As promising building blocks, porphyrins have demonstrated great potentials in visible-light photocatalytic applications, because of their electrical, optical and catalytic properties. From this perspective, we have summarized the recent significant advances on the design and photocatalytic applications of porphyrin-based nanostructures. The rational strategies, such as texture or crystal modification and interfacial heterostructuring, are described. The applications of the porphyrin-based nanostructures in photocatalytic pollutant degradation and hydrogen evolution are presented. Finally, the ongoing challenges and opportunities for the future development of porphyrin nanostructures in high-quality nanodevices are also proposed.

  10. Photoexcited iron porphyrin as biomimetic catalysts

    International Nuclear Information System (INIS)

    Bartocci, C.; Maldotti, A.; Varani, G.; Consiglio Nazionale delle Ricerche, Ferrara

    1996-01-01

    Photoexcited iron porphyrins can be of some interest in both fine and industrial chemistry in view of the preparation of new efficient biomimetic catalysts, working with high selectivity under mild temperature and pressure

  11. Nanoscaled porphyrinic metal–organic frameworks: photosensitizer delivery systems for photodynamic therapy

    Czech Academy of Sciences Publication Activity Database

    Bůžek, Daniel; Zelenka, J.; Ulbrich, P.; Ruml, T.; Křížová, I.; Lang, J.; Kubát, Pavel; Demel, Jan; Kirakci, Kaplan; Lang, Kamil

    2017-01-01

    Roč. 5, č. 9 (2017), s. 1815-1821 ISSN 2050-750X R&D Projects: GA ČR(CZ) GA16-02098S Institutional support: RVO:61388980 ; RVO:61388955 Keywords : Cell death * Crystalline materials * Cytotoxicity * Diseases * Nanoparticles Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Inorganic and nuclear chemistry; Physical chemistry (UFCH-W) Impact factor: 4.543, year: 2016

  12. Methods of forming boron nitride

    Science.gov (United States)

    Trowbridge, Tammy L; Wertsching, Alan K; Pinhero, Patrick J; Crandall, David L

    2015-03-03

    A method of forming a boron nitride. The method comprises contacting a metal article with a monomeric boron-nitrogen compound and converting the monomeric boron-nitrogen compound to a boron nitride. The boron nitride is formed on the same or a different metal article. The monomeric boron-nitrogen compound is borazine, cycloborazane, trimethylcycloborazane, polyborazylene, B-vinylborazine, poly(B-vinylborazine), or combinations thereof. The monomeric boron-nitrogen compound is polymerized to form the boron nitride by exposure to a temperature greater than approximately 100.degree. C. The boron nitride is amorphous boron nitride, hexagonal boron nitride, rhombohedral boron nitride, turbostratic boron nitride, wurzite boron nitride, combinations thereof, or boron nitride and carbon. A method of conditioning a ballistic weapon and a metal article coated with the monomeric boron-nitrogen compound are also disclosed.

  13. Riboflavin photosensitized oxidation of myoglobin

    DEFF Research Database (Denmark)

    Grippa, Juliana M.; de Zawadzki, Andressa; Grossi, Alberto Blak

    2014-01-01

    The reaction of the fresh meat pigment oxymyoglobin, MbFe(II)O, and its oxidized form metmyoglobin, MbFe(III), with triplet-state riboflavin involves the pigment protein, which is oxidatively cleaved or dimerized as shown by SDS-PAGE and Western blotting. The overall rate constant for oxidation......-excited state riboflavin by myoglobins using time-resolved fluorescence spectroscopy and a Stern-Volmer approach. Binding of riboflavin to MbFe(III) has K = (1.2 ± 0.2) × 10 mol·L with ΔH = -112 ± 22 kJ·mol and ΔS = -296 ± 75 J·mol·K. For meat, riboflavin is concluded to be a photosensitizer for protein...

  14. A near-infrared genetically targetable and activatable photosensitizer

    OpenAIRE

    He, Jianjun; Wang, Yi; Missinato, Maria A.; Onuoha, Ezenwa; Perkins, Lydia A.; Watkins, Simon C.; St. Croix, Claudette M.; Tsang, Michael; Bruchez, Marcel P.

    2016-01-01

    Upon illumination, photosensitizer molecules produce reactive oxygen species (ROS) that can be utilized for functional manipulation of living cells, including protein inactivation, targeted damage introduction, and cellular ablation. Photosensitizers used to date have been either exogenous, resulting in delivery and removal challenges, or genetically encoded proteins that form or bind a native photosensitizing molecule, resulting in a constitutively active photosensitizer in...

  15. Single Cell Responses to Spatially Controlled Photosensitized Production of Extracellular Singlet Oxygen

    DEFF Research Database (Denmark)

    Pedersen, Brian Wett; Sinks, Louise E.; Breitenbach, Thomas

    2011-01-01

    The response of individual HeLa cells to extracellularly produced singlet oxygen was examined. The spatial domain of singlet oxygen production was controlled using the combination of a membrane-impermeable Pd porphyrin-dendrimer, which served as a photosensitizer, and a focused laser, which served...... to localize the sensitized production of singlet oxygen. Cells in close proximity to the domain of singlet oxygen production showed morphological changes commonly associated with necrotic cell death. The elapsed post-irradiation “waiting period” before necrosis became apparent depended on (a) the distance...... between the cell membrane and the domain irradiated, (b) the incident laser fluence and, as such, the initial concentration of singlet oxygen produced, and (c) the lifetime of singlet oxygen. The data imply that singlet oxygen plays a key role in this process of light-induced cell death. The approach...

  16. Electron Transport through Porphyrin Molecular Junctions

    Science.gov (United States)

    Zhou, Qi

    The goal of this work is to study the properties that would affect the electron transport through a porphyrin molecular junction. This work contributes to the field of electron transport in molecular junctions in the following 3 aspects. First of all, by carrying out experiments comparing the conductance of the iron (III) porphyrin (protected) and the free base porphyrin (protected), it is confirmed that the molecular energy level broadening and shifting occurs for porphyrin molecules when coupled with the metal electrodes, and this level broadening and shifting plays an important role in the electron transport through molecular junctions. Secondly, by carrying out an in-situ deprotection of the acetyl-protected free base porphyrin molecules, it is found out that the presence of acetyl groups reduces the conductance. Thirdly, by incorporating the Matrix-assisted laser desorption/ionization (MALDI) spectrum and the in-situ deprotection prior to formation of molecular junctions, it allows a more precise understanding of the molecules involved in the formation of molecular junctions, and therefore allows an accurate analysis of the conductance histogram. The molecules are prepared by self-assembly and the junctions are formed using a Scanning Tunneling Microscopy (STM) molecular break junction technique. The porphyrin molecules are characterized by MALDI in solution before self-assembly to a gold/mica substrate. The self-assembled monolayers (SAMs) of porphyrins on gold are characterized by Ultraviolet-visible (UV-Vis) reflection spectroscopy to confirm that the molecules are attached to the substrate. The SAMs are then characterized by Angle-Resolved X-ray photoelectron spectroscopy (ARXPS) to determine the thickness and the average molecular orientation of the molecular layer. The electron transport is measured by conductance-displacement (G-S) experiments under a given bias (-0.4V). The conductance value of a single molecule is identified by a statistical analysis

  17. Synthesis and Functionalization of Porphyrins through Organometallic Methodologies.

    Science.gov (United States)

    Hiroto, Satoru; Miyake, Yoshihiro; Shinokubo, Hiroshi

    2017-02-22

    This review focuses on the postfunctionalization of porphyrins and related compounds through catalytic and stoichiometric organometallic methodologies. The employment of organometallic reactions has become common in porphyrin synthesis. Palladium-catalyzed cross-coupling reactions are now standard techniques for constructing carbon-carbon bonds in porphyrin synthesis. In addition, iridium- or palladium-catalyzed direct C-H functionalization of porphyrins is emerging as an efficient way to install various substituents onto porphyrins. Furthermore, the copper-mediated Huisgen cycloaddition reaction has become a frequent strategy to incorporate porphyrin units into functional molecules. The use of these organometallic techniques, along with the traditional porphyrin synthesis, now allows chemists to construct a wide range of highly elaborated and complex porphyrin architectures.

  18. Antimicrobial blue light inactivation of Pseudomonas aeruginosa by photo-excitation of endogenous porphyrins: In vitro and in vivo studies.

    Science.gov (United States)

    Amin, Rehab M; Bhayana, Brijesh; Hamblin, Michael R; Dai, Tianhong

    2016-07-01

    Pseudomonas aeruginosa is among the most common pathogens that cause nosocomial infections and is responsible for about 10% of all hospital-acquired infections. In the present study, we investigated the potential development of tolerance of P. aeruginosa to antimicrobial blue light by carrying 10 successive cycles of sublethal blue light inactivation. The high-performance liquid chromatographic (HPLC) analysis was performed to identify endogenous porphyrins in P. aeruginosa cells. In addition, we tested the effectiveness of antimicrobial blue light in a mouse model of nonlethal skin abrasion infection by using a bioluminescent strain of P. aeruginosa. The results demonstrated that no tolerance was developed to antimicrobial blue light in P. aeruginosa after 10 cycles of sub-lethal inactivation. HPLC analysis showed that P. aeruginosa is capable of producing endogenous porphyrins in particularly, coproporphyrin III, which are assumed to be responsible for the photodynamic effects of blue light alone. P. aeruginosa infection was eradicated by antimicrobial blue light alone (48 J/cm(2) ) without any added photosensitizer molecules in the mouse model. In conclusion, endogenous photosensitization using blue light should gain considerable attention as an effective and safe alternative antimicrobial therapy for skin infections. Lasers Surg. Med. 48:562-568, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  19. Porphyrin biodistribution in UV-exposed murine skin after methyl- and hexyl-aminolevulinate incubation

    DEFF Research Database (Denmark)

    Togsverd-Bo, Katrine; Lerche, Catharina M; Philipsen, Peter A

    2012-01-01

    Topical photodynamic therapy (PDT) with methyl-aminolevulinate (MAL) is a well-established treatment for precancerous skin lesions and non-melanoma skin cancer. Treatment outcomes are less effective for thick than for superficial lesions, which are presumed to be due to insufficient Pp......IX biodistribution in tumour tissue. Hexyl-aminolevulinate (HAL) is a more lipophilic photosensitizer precursor than MAL and may penetrate the skin to a greater depth and more homogeneously. We compared HAL- and MAL-induced PpIX accumulation in specific skin compartments using concentrations of 2%, 6% and 20% HAL...... and MAL on long-term UV-irradiated mouse skin. Furthermore, 20% HAL and 20% MAL were applied to non-irradiated skin. Porphyrin fluorescence was measured by fluorescence microscopy in selected skin regions: the epidermis, superficial dermis, deep dermis and sebaceous gland epithelium down to a depth of 1...

  20. Micro-Encapsulated Porphyrins and Phthalocyanines - New Formulations in Photodynamic Therapy

    Science.gov (United States)

    Ion, R. M.

    2017-06-01

    Photodynamic therapy (PDT), as an innovative method for cancer tretament is based on a concerted action of some drugs, called sensitizers, which generate reactive oxygen species via a photochemical mechanism, leading to cellular necrosis or apoptosis. The present work aims at loading some sensitizers, as porphyrins (P) and phthalocyanines (Pc) into alginate particles. Particles were prepared by dropping alginate into an aqueous solution containing P or Pc and CaCl2, which allows the formation of particles through ionic crosslinking. It was obtained P or Pc loaded alginate beads with an average diameter of about 100 μm. For these systems, this paper analyses the spectroscopic properties, encapsulation into microcapsules, controlled releasing action and their photosensitizer capacity (singlet oxygen generation).

  1. Ion-induced stacking of photosensitizer molecules can remarkably affect the luminescence detection of singlet oxygen in Candida albicans cells

    Science.gov (United States)

    Felgenträger, Ariane; Gonzales, Fernanda Pereira; Maisch, Tim; Bäumler, Wolfgang

    2013-04-01

    Singlet oxygen (O21) is an important reactive intermediate in photodynamic reactions, particularly in antimicrobial PDT (aPDT). The detection of O21 luminescence is frequently used to elucidate the role of O21 in various environments, particularly in microorganisms and human cells. When incubating the fungus, Candida albicans, with porphyrins XF73 (5,15-bis-[4-(3-Trimethylammonio-propyloxy)-phenyl]-porphyrin) or TMPyP (5,10,15,20-Tetrakis(1-methyl-4-pyridinio)-porphyrin tetra(p-toluenesulfonate)), the O21 luminescence signals were excellent for TMPyP. In case of XF73, the signals showed strange rise and decay times. Thus, O21 generation of XF73 was investigated and compared with TMPyP. Absorption spectroscopy of XF73 showed a change in absorption cross section when there was a change in the concentration from 1×10-6 M to 1×10-3 M indicating an aggregation process. The addition of phosphate buffered saline (PBS) substantially changed O21 luminescence in XF73 solution. Detailed experiments provided evidence that the PBS constituents NaCl and KCl caused the change of O21 luminescence. The results also indicate that Cl- ions may cause aggregation of XF73 molecules, which in turn enhances self-quenching of O21 via photosensitizer molecules. These results show that some ions, e.g., those present in cells in vitro or added by PBS, can considerably affect the detection and the interpretation of time-resolved luminescence signals of O21, particularly in in vitro and in vivo. These effects should be considered for any other photosensitizer used in photodynamic processes.

  2. Artificial Red Blood Cells as Potential Photosensitizers in Dye Laser Treatment Against Port-Wine Stains.

    Science.gov (United States)

    Rikihisa, Naoaki; Watanabe, Shoji; Saito, Yoshiaki; Sakai, Hiromi

    2017-04-13

    We suggest a novel method that uses artificial blood cells (hemoglobin vesicles, Hb-Vs) as photosensitizers in dye laser treatment (at 595-nm wavelength) for port-wine stains (i.e., capillary malformations presenting as red birthmarks) based on the results of animal experiments. As compared with human red blood cells, Hb-Vs have the same absorbance of 595 nm wavelength light and produce the same level of heat following dye laser irradiation. Small sized Hb-Vs (250 nm) distribute in the plasma phase in blood and tend to flow in the marginal zone of microvessels. Intravenous injections of Hb-Vs caused the dilatation of microvessels, and dye laser treatment with Hb-Vs destroyed the vessel wall effectively. Following the intravenous injection of Hb-Vs, the microvessels contained more Hb that absorbed laser photons and produced heat. This extra Hb tended to flow near the endothelial cells, which were the target of the laser treatment. These attributes of Hb-Vs will potentially contribute to enhancing the efficacy of dye laser treatment for port-wine stains. Hemoglobin is a type of porphyrin. Thus, our proposed treatment may have aspects of photodynamic therapy using porphyrin that leads to a cytotoxicity effect by active oxygen.

  3. Assembly of High-Potency Photosensitizer-Antibody Conjugates through Application of Dendron Multiplier Technology.

    Science.gov (United States)

    Bryden, Francesca; Maruani, Antoine; Rodrigues, João M M; Cheng, Miffy H Y; Savoie, Huguette; Beeby, Andrew; Chudasama, Vijay; Boyle, Ross W

    2018-01-17

    Exploitation of photosensitizers as payloads for antibody-based anticancer therapeutics offers a novel alternative to the small pool of commonly utilized cytotoxins. However, existing bioconjugation methodologies are incompatible with the requirement of increased antibody loading without compromising antibody function, stability, or homogeneity. Herein, we describe the first application of dendritic multiplier groups to allow the loading of more than 4 porphyrins to a full IgG antibody in a site-specific and highly homogeneous manner. Photophysical evaluation of UV-visible absorbance and singlet oxygen quantum yields highlighted porphyrin-dendron 14 as the best candidate for bioconjugation; with subsequent bioconjugation producing a HER2-targeted therapeutic with average loading ratios of 15.4:1. In vitro evaluation of conjugate 18 demonstrated a nanomolar photocytotoxic effect in a target cell line, which overexpresses HER2, with no observed photocytotoxicity at the same concentration in a control cell line which expresses native HER2 levels, or in the absence of irradiation with visible light.

  4. Metal complexes of substituted Gable porphyrins as oxidation catalysts

    Science.gov (United States)

    Lyons, James E.; Ellis, Jr., Paul E.; Wagner, Richard W.

    1996-01-01

    Transition metal complexes of Gable porphyrins having two porphyrin rings connected through a linking group, and having on the porphyrin rings electron-withdrawing groups, such as halogen, nitro or cyano. These complexes are useful as catalysts for the oxidation of organic compounds, e.g. alkanes.

  5. Re (I) bridged porphyrin dyads, triads and tetrads

    Indian Academy of Sciences (India)

    The porphyrin dyads have been explored for singlet-singlet energy transfer studies and porphyrin squares have been used for catalysis, chemical sensing, molecular sieving and photocurrent production studies. An overview of synthesis of Re(I) bridged porphyrin dyads, triads and tetrads and their interesting photophysical ...

  6. New Photosensitizers for Photodynamic Therapy in Gastroenterology

    Directory of Open Access Journals (Sweden)

    SG Bown

    1999-01-01

    Full Text Available Most applications of photodynamic therapy (PDT in gastroenterology to date have used porfimer sodium as the photosensitizing agent. For destroying small lesions in the wall of the gastrointestinal tract in inoperable patients, it has proved to be most effective, but attempts to achieve circumferential mucosal ablation, as in the treatment of Barrett’s esophagus, have led to a high incidence of strictures, and all patients have cutaneous photosensitivity, which can last up to three months. Two new photosensitizers are of particular interest to gastroenterologists. PDT with metatetrahydroxyphenyl chlorin produces a similar biological effect as PDT with porfimer sodium, but the light doses required are much smaller, and cutaneous photosensitivity lasts only two to three weeks. Further, it can be used with percutaneous light delivery to destroy localized pancreatic cancers. The photosensitizing agent 5-amino levulinic acid, converted in vivo into the photoactive derivative protoporphyrin IX, sensitizes the mucosa much more than the underlying layers. This makes it feasible to destroy areas of abnormal mucosa without damaging the underlying muscle and is, therefore, better for treating Barrett’s esophagus. Detailed clinical studies are required to establish the real role of PDT with the use of these and other new photosensitizers.

  7. Polystyrene sulfonate-porphyrin assemblies: influence of polyelectrolyte and porphyrin structure.

    Science.gov (United States)

    Ruthard, Christian; Maskos, Michael; Kolb, Ute; Gröhn, Franziska

    2011-05-19

    In this study, electrostatic self-assembly of different polystyrene sulfonates and a set of tetravalent cationic porphyrins is investigated. It is shown that association of linear polystyrene sulfonates of different molar masses yields finite size nanoscale assemblies that are stable in aqueous solution. Aggregates are compared to the ones of cylindrical brushes, revealing that both form assemblies in the 100 nm range with the charge ratio (molar ratio of porphyrin charges to polyelectrolyte charges) being determining, while the morphology of the resulting network-like assemblies is different for both polyelectrolyte architectures. For the smallest 8k polystyrene sulfonate, in addition, stoichiometric conditions differ. The influence of the molecular porphyrin structure was investigated by comparing meso-tetrakis(4-(trimethyl-ammonium)phenyl)porphyrin (TAPP) with its Cu(II) and Zn(II) loaded analogues and meso-tetrakis(4-N-methylpyridinium)porphyrin (TMPyP), revealing differences in stacking tendency and geometry. Additionally, the TMPyP accumulates more in the inside of the brush than the other porphyrins, likely due to the different position of its charged groups. The supramolecular nanostructures formed were characterized by UV-vis spectroscopy, light scattering, atomic force microscopy, cryo transmission electron microscopy, and small-angle neutron scattering. Results may build a valuable basis for the use of polyelectrolyte-porphyrin assemblies in medicine, catalysis, or energy conversion. © 2011 American Chemical Society

  8. Riboflavin photosensitized oxidation of myoglobin.

    Science.gov (United States)

    Grippa, Juliana M; de Zawadzki, Andressa; Grossi, Alberto B; Skibsted, Leif H; Cardoso, Daniel R

    2014-02-05

    The reaction of the fresh meat pigment oxymyoglobin, MbFe(II)O₂, and its oxidized form metmyoglobin, MbFe(III), with triplet-state riboflavin involves the pigment protein, which is oxidatively cleaved or dimerized as shown by SDS-PAGE and Western blotting. The overall rate constant for oxidation of MbFe(II)O₂ by ³Rib is (3.0 ± 0.5) × 10⁹ L·mol⁻¹·s⁻¹ and (3.1 ± 0.4) × 10⁹ L·mol⁻¹·s⁻¹ for MbFe(III) in phosphate buffer of pH 7.4 at 25 °C as determined by laser flash photolysis. The high rates are rationalized by ground state hydrophobic interactions as detected as static quenching of fluorescence from singlet-excited state riboflavin by myoglobins using time-resolved fluorescence spectroscopy and a Stern-Volmer approach. Binding of riboflavin to MbFe(III) has K(a) = (1.2 ± 0.2) × 10⁴ mol·L⁻¹ with ΔH° = -112 ± 22 kJ·mol⁻¹ and ΔS° = -296 ± 75 J·mol⁻¹·K⁻¹. For meat, riboflavin is concluded to be a photosensitizer for protein oxidation but not for discoloration.

  9. Boron nitride converted carbon fiber

    Science.gov (United States)

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  10. Dualism of Sensitivity and Selectivity of Porphyrin Dimers in Electroanalysis.

    Science.gov (United States)

    Lisak, Grzegorz; Tamaki, Takashi; Ogawa, Takuji

    2017-04-04

    This work uncovers the application of porphyrin dimers for the use in electroanalysis, such as potentiometric determination of ions. It also puts in question a current perception of an occurrence of the super-Nernstian response, as a result of the possible dimerization of single porphyrins within an ion-selective membrane. To study that, four various porphyrin dimers were used as ionophores, namely, freebase-freebase, Zn-Zn, Zn-freebase, and freebase-Zn. Since the Zn-freebase and freebase-Zn porphyrin dimers carried both anion- and cation-sensitive porphyrin units, their application in ISEs was utilized in both anion- and cation-sensitive sensors. With respect to the lipophilic salt added, both porphyrins dimers were found anion- and cation-sensitive. This allowed using a single molecule as novel type of versatile ionophore (anion- and cation-selective), simply by varying the membrane composition. All anion-sensitive sensors were perchlorate-sensitive, while the cation-selective sensors were silver-sensitive. The selectivity of the sensors depended primarily on the porphyrin dimers in the ion-selective membrane. Furthermore, the selectivity of cation-sensitive dimer based sensors was found significantly superior to the ones measured for the single porphyrin unit based sensors (precursors of the porphyrin dimers). Thus, the dimerization of single porphyrins may actually be a factor to increase or modulate porphyrin selectivity. Moreover, in the case of cation-sensitive sensors, the selectivity vastly depended on the order of porphyrin units in the dimer. This opens a new approach of regulating and adjusting sensitivity and selectivity of the sensor through the application of complex porphyrin systems with more than one porphyrin units with mix sensitive porphyrins.

  11. Electron injection dynamics in high-potential porphyrin photoanodes.

    Science.gov (United States)

    Milot, Rebecca L; Schmuttenmaer, Charles A

    2015-05-19

    promising sensitizers because their high reduction potentials are compatible with the energy requirements of water oxidation. TRTS of free-base and metalated pentafluorophenyl porphyrins reveal inefficient electron injection into TiO2 nanoparticles but more efficient electron injection into SnO2 nanoparticles. With SnO2, injection time scales depend strongly on the identity of the central substituent and are affected by competition with excited-state deactivation processes. Heavy or paramagnetic metal ions increase the electron injection time scale by roughly one order of magnitude relative to free-base or Zn(2+) porphyrins due to the possibility of electron injection from longer-lived, lower-lying triplet states. Furthermore, electron injection efficiency loosely correlates with DSSC performance. The carboxylate anchoring group is commonly used to bind DSSC sensitizers to metal oxide surfaces but typically is not stable under the aqueous and oxidative conditions required for water oxidation. Electron injection efficiency of several water-stable alternatives, including phosphonic acid, hydroxamic acid, acetylacetone, and boronic acid, were evaluated using TRTS, and hydroxamate was found to perform as well as the carboxylate. The next challenge is incorporating a water oxidation catalyst into the design. An early example, in which an Ir-based precatalyst is cosensitized with a fluorinated porphyrin, reveals decreased electron injection efficiency despite an increase in photocurrent. Future research will seek to better understand and address these difficulties.

  12. Photovoltaic Performance of ZnO Nanosheets Solar Cell Sensitized with Beta-Substituted Porphyrin

    Directory of Open Access Journals (Sweden)

    Arumugam Mahesh

    2011-01-01

    Full Text Available The photoanode of dye-sensitized solar cell (DSSC was fabricated using two-dimensional ZnO nanosheets (2D ZnO NSs sensitized with beta-substituted porphyrins photosensitizer, and its photovoltaic performance in solid-state DSSC with TiO2 nanotubes (TiO2 TNs modified poly (ethylene oxide (PEO polymer electrolyte was studied. The ZnO NSs were synthesized through hydrothermal method and were characterized through high-resolution scanning electron microscopy (HRSEM, diffused reflectance spectra (DRS, photoluminescence spectra (PL, and X-ray diffraction (XRD analysis. The crystallinity of the polymer electrolytes was investigated using X-ray diffraction analysis. The photovoltaic performance of the beta-substituted porphyrins sensitized solar cells was evaluated under standard AM1.5G simulated illumination (100 mW cm−2. The efficiency of energy conversion from solar to electrical due to 2D ZnO NSs based DSSCs is 0.13%, which is about 1.6 times higher than that of the control DSSC using ZnO nanoparticles (ZnO NPs as photoanode (0.08%, when TiO2 NTs fillers modified PEO electrolyte was incorporated in the DSSCs. The current-voltage (- and photocurrent-time (- curves proved stable with effective collection of electrons, when the 2D ZnO nanostructured photoanode was introduced in the solid-state DSSC.

  13. Phototoxic Activity and DNA Interactions of Water-Soluble Porphyrins and Their Rhenium(I) Conjugates.

    Science.gov (United States)

    Mion, Giuliana; Gianferrara, Teresa; Bergamo, Alberta; Gasser, Gilles; Pierroz, Vanessa; Rubbiani, Riccardo; Vilar, Ramon; Leczkowska, Anna; Alessio, Enzo

    2015-11-01

    In the search for alternative photosensitizers for use in photodynamic therapy (PDT), herein we describe two new water-soluble porphyrins, a neutral fourfold-symmetric compound and a +3-charged tris-methylpyridinium derivative, in which either four or one [1,4,7]-triazacyclononane (TACN) units are connected to the porphyrin macrocycle through a hydrophilic linker; we also report their corresponding tetracationic Re(I) conjugates. The in vitro (photo)toxic effects of the compounds toward the human cell lines HeLa (cervical cancer), H460M2 (non-small-cell lung carcinoma), and HBL-100 (non-tumorigenic epithelial cells) are reported. Three of the compounds are not cytotoxic in the dark up to 100 μm, and the fourfold-symmetric couple revealed very good phototoxic indexes (PIs). The intracellular localization of all derivatives was studied in HeLa cells by confocal fluorescence microscopy. Although low nuclear localization was observed for some of them, it still prompted us to investigate their capacity to bind both quadruplex and duplex DNA; we observed significant selectivity in the tris-methylpyridinium derivatives for G-quadruplex interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Mitochondrial-targeted photosensitizer-loaded folate-albumin nanoparticle for photodynamic therapy of cancer.

    Science.gov (United States)

    Battogtokh, Gantumur; Ko, Young Tag

    2017-02-01

    The objective of this study was to develop a mitochondria-targeted photosensitizer (PS) for photodynamic therapy (PDT). Herein, a porphyrin-derivative photosensitizer, pheophorbide-a (PheoA), was conjugated to carboxybutyltriphenylphosphonium (TPP) via a carbodiimide linkage to enhance mitochondrial targeting and TPP-PheoA conjugate was further loaded into folate-cholesteryl albumin (FA-chol-BSA) nanoparticles (NPs) to improve its biocompatibility. Cellular uptake results showed that TPP-PheoA and TPP-PheoA@FA-chol-BSA NPs were readily taken up by B16F10 and HeLa cells. Further in vitro studies exhibited that TPP-PheoA and its nanoparticle primarily accumulate in the mitochondria, greatly generate ROS, lead mitochondrial disruption and cell apoptosis, and have higher phototoxicity against cancer cells. In vivo bioimaging and the in vivo antitumor studies indicated that TPP-PheoA@FA-chol-BSA NP greatly accumulated in the tumor area and significantly suppress the tumor growth as compared to PheoA@FA-chol-BSA NP in tumor-bearing mice. Taken together, TPP-PheoA@FA-chol-BSA NP could be a promising mitochondria-targeted PS for image-guided PDT. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Thin molecular films of supramolecular porphyrins

    Directory of Open Access Journals (Sweden)

    KOITI ARAKI

    2000-03-01

    Full Text Available A relevant series of symmetric supramolecular porphyrins has been obtained by attaching four [Ru II(bipy2Cl] groups to the pyridyl substituents of meso-tetra(4-pyridylporphyrin and its metallated derivatives. These compounds display a rich electrochemistry and versatile catalytic, electrocatalytic and photochemical properties, associated with the ruthenium-bipyridine and the porphyrin complexes. These properties can be transferred to the electrodes by attaching thin molecular films of the compounds, by dip-coating, electrostatic assembly or electropolymerization. In this way, the interesting properties of those supermolecules and supramolecular assemblies can be used to prepare molecular devices and sensors.

  16. Three Short Stories about Hexaarylbenzene-Porphyrin Scaffolds.

    Science.gov (United States)

    Lungerich, Dominik; Hitzenberger, Jakob F; Donaubauer, Wolfgang; Drewello, Thomas; Jux, Norbert

    2016-11-14

    A feasible two-step synthesis and characterization of a full series of hexaarylbenzene (HAB) substituted porphyrins and tetrabenzoporphyrins is presented. Key steps represent the microwave-assisted porphyrin condensation and the statistical Diels-Alder reaction to the desired HAB-porphyrins. Regarding their applications, they proved to be easily accessible and effective high molecular mass calibrants for (MA)LDI mass spectrometry. The free-base and zinc(II) porphyrin systems, as well as the respective tetrabenzoporphyrins, demonstrate in solid state experiments strong red- and near-infrared-light emission and are potentially interesting for the application in "truly organic" light-emitting devices. Lastly, they represent facile precursors to large polycyclic aromatic hydrocarbon (PAH) substituted porphyrins. We prepared the first tetra-hexa-peri-hexabenzocoronene substituted porphyrin, which represents the largest prepared PAH-porphyrin conjugate to date. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. [Pharmaceutical chemistry of drug-initiated photosensitivity].

    Science.gov (United States)

    Rácz, Ákos; Tóth, Lívia

    2015-01-01

    The photosensitivity originated from drugs is a common problem in medical and pharmaceutical practice. It is of prominent importance in drug development and in regulatory issues. The photosensitizer effect of drug substances is determined by their chemical structures, and it mainly originates from aromatic chromophore systems and photo-dissociable bonds forming free radicals. The photodegradation may happen in many different types of chemical reaction pathways. Our aim is to demonstrate in this review the interrelations between structure and photodegradation. We show examples for the different reaction types, with drugs from different pharmacologic therapeutic classes. The in vivo chemical reactivity of photodegradates of pharmaceutical substances, the in vitro methods of investigation for testing photoreactivity and phototoxicity, and briefly the clinical tests for photosensitivity disorders are also discussed.

  18. N'-formylkynurenine-photosensitized inactivation of bacteriophage

    International Nuclear Information System (INIS)

    Walrant, P.; Santus, R.; Redpath, J.L.; Pileni, M.P.

    1976-01-01

    Measurements have been made of the sensitizing properties of N'-formylkynurenine (FK) on bacteriophages, as part of a wider study of FK photosensitization of systems which have both protein and DNA components. Suspensions of bacteriophages T 6 and T 7 were near-U.V. (lambda > 320 nm) irradiated in solutions saturated with either O 2 or He in the presence of 5 x 10 -4 M FK. The survival curves obtained demonstrated that FK can act as a photosensitizer for biological inactivation. The involvement of singlet oxygen as one factor in this FK sensitized inactivation was clearly demonstrated by the increased rate of inactivation when the phage were suspended in O 2 -saturated D 2 O, in place of water, during irradiation. The complex mechanism of phage inactivation must involve direct interaction between excited FK and substrate, as well as singlet oxygen. FK is therefore a new natural photosensitizer of significance in cell photochemistry induced by sunlight. (U.K.)

  19. Photosensitive Gaseous Detectors for Cryogenic Temperature Applications

    CERN Document Server

    Periale, L; Iacobaeus, C; Lund-Jensen, B; Picchi, P; Pietropaolo, F

    2007-01-01

    There are several proposals and projects today for building LXe Time Projection Chambers (TPCs) for dark matter search. An important element of these TPCs are the photomultipliers operating either inside LXe or in vapors above the liquid. We have recently demonstrated that photosensitive gaseous detectors (wire type and hole-type) can operate perfectly well until temperatures of LN2. In this paper results of systematic studies of operation of the photosensitive version of these detectors (combined with reflective or semi-transparent CsI photocathodes) in the temperature interval of 300-150 K are presented. In particular, it was demonstrated that both sealed and flushed by a gas detectors could operate at a quite stable fashion in a year/time scale. Obtained results, in particular the long-term stability of photosensitive gaseous detectors, strongly indicate that they can be cheap and simple alternatives to photomultipliers or avalanche solid-state detectors in LXe TPC applications.

  20. Porphyrin formation and its regulation in Arthrobacter

    NARCIS (Netherlands)

    Kortstee, G.J.J.

    1969-01-01

    Porphyrins (tetrapyrroles) are the basic compounds of a number of substances functioning in living organisms as carriers of oxygen (hemoglobin), carriers of electrons (cytochromes) or as a trap for radiant energy (chlorophyll). In these active forms the tetrapyrroles contain a metal and are

  1. Photodynamic Efficiency of Porphyrins Encapsulated into Polysilsesquioxanes

    Czech Academy of Sciences Publication Activity Database

    Rychtáriková, Renata; Šabata, Stanislav; Hetflejš, Jiří; Kuncová, Gabriela

    2012-01-01

    Roč. 66, č. 4 (2012), s. 269-277 ISSN 0366-6352 R&D Projects: GA MŠk ME 892; GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40720504 Keywords : porphyrin * immobilization * specific surface area Subject RIV: CC - Organic Chemistry Impact factor: 0.879, year: 2012

  2. Sulfonated graphenes catalyzed synthesis of expanded porphyrins ...

    Indian Academy of Sciences (India)

    Sulfonated graphene; expanded porphyrins; heterogeneous catalysis; solid acid; non-covalent interaction. 1. Introduction. Graphene, an important allotropic member of carbon, has received much attention owing to its interest- ing properties in material science with wide range of applications in energy devices, electronics, ...

  3. Sulfonated graphenes catalyzed synthesis of expanded porphyrins ...

    Indian Academy of Sciences (India)

    A newer synthesis of sulfonic acid functionalized graphenes have been developed, which have been characterized, examined as heterogeneous solid acid carbocatalyst in the synthesis of selected expanded porphyrins in different reaction conditions. This environment-friendly catalyst avoids the use of toxic catalysts and ...

  4. Heptaphyrins: Expanded porphyrins with seven heterocyclic rings

    Indian Academy of Sciences (India)

    Unknown

    -mail: tkc@iitk.ac.in ... The syntheses of expanded porphyrins continue to attract the attention of chemists because of their diverse .... The aromatic nature of the heptaphyrins, 7–9, was proved by various analytical methods. The Soret-like ...

  5. Porphyrins profile by high performance liquid chromatography ...

    African Journals Online (AJOL)

    E. Fateen

    2008-09-07

    Sep 7, 2008 ... tation of urinary porphyrins by liquid chromatography tandem mass spectrometry (LC/MS/MS) and thereby the ... by HPLC/ESI/MS/MS used in this study is a modification for the method Stoev et al. while ion mapping technique is a ..... designed for application by the Biochemical Genetics Depart- ment team.

  6. Sulfonated graphenes catalyzed synthesis of expanded porphyrins ...

    Indian Academy of Sciences (India)

    Handbook of Porphyrin Science 2010 (Singapore: World. Scientific Publishing). 10. Mishra R and Chandrashekhar T K 2008 Acc. Chem. Res. 41 265. 11. Jasat A and Dolphin D 1997 Chem. Rev. 97 2267. 12. Saito S and Osuka A 2011 Angew. Chem. Int. Ed. 50. 4342. 13. Shin J-Y, Furuta H, Yoza K, Igarashi S and Osuka A.

  7. Porphyrin-anthraquinone dyads: Synthesis, spectroscopy and ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 117; Issue 2 ... Analysis of the data reveals that the spectral and electrochemical properties of the individual chromophoric entities are retained and that there is no specific - interaction between the porphyrin and anthraquinone subunits. H2L2 and ZnL2 are shown ...

  8. Toluidine blue O and porphyrin-mediated photodynamic therapy on three main pathogenic bacteria of periodontitis using portable LED phototherapy device

    Directory of Open Access Journals (Sweden)

    Xuewei Jiang

    2015-07-01

    Full Text Available Photodynamic therapy (PDT has been commonly used in treating many diseases, such as cancer and infectious diseases. We investigated the different effects of PDT on three main pathogenic bacteria of periodontitis — Prevotella melaninogenica (P.m., Porphyromonas gingivalis (P.g. and Aggregatibacter actinomycetemcomitans (A.a.. The portable red light-emitting diode (LED phototherapy device was used to assess the exogenous PDT effects with different light doses and photosensitizer concentrations (Toluidine blue O, TBO. The portable blue LED phototherapy device was used to assess the endogenous PDT effects with the use of endogenous photosensitizers (porphyrin under different light doses. We found out that both exogenous and endogenous PDT were able to restrict the growth of all the three bacteria significantly. Moreover, the optimal PDT conditions for these bacteria were obtained through this in vitro screening and could guide the clinical PDT on periodontitis.

  9. Reactions of Hydroxylamine with Metal Porphyrins.

    Science.gov (United States)

    Choi, In-Kyu; Liu, Yanming; Wei, Zhongcheng; Ryan, Michael D.

    1997-07-02

    The reaction of hydroxylamine with a series of metal porphyrins was examined in methanol/chloroform media. The reductive nitrosylation reaction was observed for the manganese and iron porphyrins, leading to a nitrosyl complex that precipitated out of the solution in good isolatable yield (80-90%). This reaction could be used synthetically for the generation of iron and manganese porphyrin nitrosyl complexes and was particularly useful for making isotopically labeled nitrosyl complexes. On the other hand, Co(II)(TPP) and Cr(TPP)(Cl) did not react with hydroxylamine under anaerobic conditions. With trace amounts of oxygen, the reaction of Co(II)(TPP) with hydroxylamine led to the formation of a stable cobalt(III)-bis(hydroxylamine) complex. The infrared, resonance Raman, and proton NMR spectra were consistent with a cobalt(III)-bis(hydroxylamine) complex. The cyclic voltammetry and visible spectroelectrochemistry of this complex were examined. The one-electron reduction of Co(III)(TPP)(NH(2)OH)(2)(+) formed Co(II)(TPP), for which there was no evidence for the coordination of hydroxylamine. Further reduction led to Co(I)(TPP)(-), which reacted with the halogenated solvent to form a cobalt-alkyl complex. The difference in the reactivity of these four metal porphyrins with hydroxylamine correlated well with their E(1/2) values. Iron(III) and manganese(III) porphyrins were relatively easy to reduce and readily underwent the reductive nitrosylation reaction, while cobalt(II) and chromium(III) porphyrins are unreactive. The one-electron oxidation of the hydroxylamine complex with a M(III) porphyrin would be expected to oxidize the N-atom in the coordinated hydroxylamine. The oxidation of M(III)(NH(2)OH) with the loss of a proton would form M(II)(N(I)H(2)O)(+) by an internal electron transfer, which will eventually lead to M(NO). The relationship between the reductive nitrosyl reaction and the enzymatic interconversion of NO and hydroxylamine was discussed.

  10. Photoinduced electron transfer in some photosensitive molecules ...

    Indian Academy of Sciences (India)

    Unknown

    Semiconductor; photocatalytic; photosensitive molecule; intramolecular charge transfer; TiO2/Y-zeolite. 1. Introduction. The consumption of energy has grown exponentially over the last two decades due to rapid industrialization and better living standards throughout the world. Among the various forms of energy available ...

  11. Photosensitivity of layered semiconductor propolis heterocontact

    Science.gov (United States)

    Drapak, Stepan I.; Orletskii, Volodymyr B.; Bahtinov, Anatolii P.; Kovalyuk, Zakhar D.; Fotiy, Vasyl D.

    2003-03-01

    Room temperature photosensitivity and its spectral distribution are investigated for a hetercontact between a layered semiconductor (p-InSe) and a biological entity (propolis). The obtained heterocontacts has a maximum photosensitivity >= 10^4 V/W. It is shown that the form of spectral sensitivity curve depends on the way of the heterocontact preparation. The long-wave edge of relative quantum efficiency varies from hν =1.2 eV (the energy gap for InSe at T=300 K) to 1.6 eV depending on a state of aggregation of propolis. The maximum photosensitivity in the long-wave spectral range takes place when the propolis layer is under illumination. The obtained peculiarities of the photoelectrical properties cannot be explained in the framework of the classical description of photosensitivity spectral description (the window effect) what follows from the optical absorption measurements for InSe and propolis in the range hν chemical composition of propolis, a product from honey bee, must be taken into account.

  12. Synthesis and characterization of ether-linked porphyrins

    Directory of Open Access Journals (Sweden)

    Radchada Buntem

    2009-07-01

    Full Text Available The ether-linked porphyrin dimers in this research work were prepared from coupling reaction between suitableporphyrin precursors and linkers in the presence of potassium carbonate. The structures of all synthesized compounds werecharacterized by spectroscopic methods. The UV/Visible absorption maxima and extinction coefficients did not show any significant difference among these porphyrin dimers. This indicates that the length of the linker did not affect the absorption property of the dimers. However, different metal ions bonding to the porphyrin moiety affect the different absorption maxima of the porphyrin dimers. It was also found that the position of the linker on the phenyl ring of porphyrin does not affect the visible absorption pattern or the proton chemical shifts of the porphyrin core as found in the case of Zn2(metaC-dimer (13(compared with the data obtained for Zn2C2-dimer (3.

  13. Iron porphyrins doped sol-gel glasses: a chemometric study

    International Nuclear Information System (INIS)

    Sacco, Herica C.; Vidoto, Ednalva A.; Nascimento, Otaciro R.

    2000-01-01

    This paper describes the optimized conditions for preparation of iron porphyrin-template doped silica Fe PDS-template) obtained by the sol-gel process. The following porphyrins (Fe P) were used: Fe TFPP Cl, Fe TDCSPP(Na) 4 Cl and Fe TCPP(Na) 4 Cl. Pyridine or 4-phenylimidazole was used as template. The variables that present significant influence on iron porphyrin loading on xerogel were identified and the values that maximize the iron porphyrin loading on xerogel were established . The variables (Solvent volume, fractional factorial design in two levels, 2 5-1 type, generating 16 total experiments for each Fe P studied. (author)

  14. Iron porphyrins doped sol-gel glasses: a chemometric study

    Energy Technology Data Exchange (ETDEWEB)

    Sacco, Herica C.; Vidoto, Ednalva A.; Nascimento, Otaciro R. [Soap Paulo Univ (USP), Sao Carlos (Brazil). Inst. de Fisica; Biazzotto, Juliana C.; Serra, Osvaldo A.; Iamamoto, Yassuko [Sao Paulo Univ. (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras; Ciuffi, Katia J.; Mello, Cesar A.; Oliveira, Daniela C. de [Universidade de Franca , SP (Brazil)

    2000-07-01

    This paper describes the optimized conditions for preparation of iron porphyrin-template doped silica Fe (PDS-template) obtained by the sol-gel process. The following porphyrins (Fe P) were used: Fe TFPP Cl, Fe TDCSPP(Na){sub 4}Cl and Fe TCPP(Na){sub 4} Cl. Pyridine or 4-phenylimidazole was used as template. The variables that present significant influence on iron porphyrin loading on xerogel were identified and the values that maximize the iron porphyrin loading on xerogel were established. The variables Solvent volume, fractional factorial design in two levels, 2{sup 5-1} type, generating 16 total experiments for each Fe P studied. (author)

  15. A Study of Porphyrins in Petroleum Source Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Huseby, Berit

    1996-12-31

    This thesis discusses several aspects of porphyrin geochemistry. Degradation experiments have been performed on the Messel oil shale (Eocene, Germany) to obtain information on porphyrins bound or incorporated into macromolecular structures. Thermal heating of the preextracted kerogen by hydrous pyrolysis was used to study the release of porphyrins and their temperature dependent changes during simulated diagenesis and catagenesis. Selective chemical degradation experiments were performed on the preextracted sediment to get more detailed information about porphyrins that are specifically bound to the macromolecular structures via ester bonds. From the heating experiments, in a separate study, the porphyrin nitrogen content in the generated bitumens was compared to the bulk of organic nitrogen compounds in the fraction. The bulk nitrogen contents in the generated bitumens, the water phase and the residual organic matter was recorded to establish the distribution of nitrogen between the kerogen and product phases. Porphyrins as biomarkers were examined in naturally matured Kimmeridge clay source rocks (Upper Jurassic, Norway), and the use of porphyrins as general indicators of maturity was evaluated. Underlying maturity trends in the biomarker data was investigated by Partial Least Squares analysis. Porphyrin as indicators of depositional conditions was also addressed, where the correlations between the (amounts) abundance of nickel and vanadyl porphyrins were mapped together with other descriptors that are assumed to be indicative of redox depositional conditions. 252 refs., 28 figs., 4 tabs.

  16. Studies of transfer reactions of photosensitized electrons involving complexes of transition metals in view of solar energy storage

    International Nuclear Information System (INIS)

    Takakubo, Masaaki

    1984-01-01

    This research thesis addresses electron transfer reactions occurring during photosynthesis, for example, photosensitized reaction in which chlorophyll is the sensitizer. More specifically, the author studied experimentally electron photo-transfers with type D sensitizers (riboflavin, phenoxazine and porphyrin), and various complexes of transition metals. After a presentation of these experiments, the author describes the photosensitisation process (photo-physics of riboflavin, oxygen deactivation, sensitized photo-oxidation and photo-reduction). The theoretical aspect of electron transfer is then addressed: generalities, deactivation of the riboflavin triplet, initial efficiency of electron transfer. Experimental results on three basic processes (non-radiative deactivation, energy transfer, electron transfer) are interpreted in a unified way by using the non-radiative transfer theory. Some applications are described: photo-electrochemical batteries, photo-oxidation and photo-reduction of the cobalt ion

  17. Immobilization of Porphyrins in Poly(hydroxymethylsiloxane)

    Czech Academy of Sciences Publication Activity Database

    Šabata, Stanislav; Hetflejš, Jiří; Rychtáriková, Renata; Kuncová, Gabriela; Lang, Kamil; Kubát, Pavel

    2009-01-01

    Roč. 63, č. 4 (2009), s. 438-444 ISSN 0366-6352 R&D Projects: GA ČR(CZ) GA203/06/1244; GA MŠk OC 121 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40320502; CEZ:AV0Z40400503 Keywords : poly(hydroxymethylsiloxane) * fluorescence spectra * porphyrin Subject RIV: CC - Organic Chemistry Impact factor: 0.791, year: 2009

  18. Supramolecular chemistry of bis-porphyrins

    OpenAIRE

    Hernández Eguía, Laura P.

    2010-01-01

    (Base de datos de tesis doctorales TESEO) English versionIn this doctoral thesis two main aspects are developed. The first is the synthesis of bis-porphyrin receptors metallated with zinc, both acyclic and cyclic, and with different degrees of saturation of the carbon chain, and the second deals with the studies of complexation with ligands of different types and properties: amines and fullerenes. The first ligands are connected by metal-nitrogen coordination between the nitrogen of the liga...

  19. Structures and properties of spatially distorted porphyrins

    International Nuclear Information System (INIS)

    Golubchikov, Oleg A; Kuvshinova, Elizaveta M; Pukhovskaya, Svetlana G

    2005-01-01

    The published data on the structures and properties of porphyrins with distorted aromatic macrocycles are generalised and analysed. Data on the crystal structures, spectra and kinetics of formation and dissociation of their coordination derivatives are summarised. It is demonstrated that the distortion of the planar structure of the tetrapyrrole core is one of the most efficient means of controlling spectral, physicochemical and coordination properties of these compounds.

  20. 2-Bromo-5-hydroxyphenylporphyrins for photodynamic therapy: photosensitization efficiency, subcellular localization and in vivo studies.

    Science.gov (United States)

    Laranjo, Mafalda; Serra, Arménio C; Abrantes, Margarida; Piñeiro, Marta; Gonçalves, Ana C; Casalta-Lopes, João; Carvalho, Lina; Sarmento-Ribeiro, Ana B; Rocha-Gonsalves, António; Botelho, Filomena

    2013-02-01

    Photodynamic therapy (PDT) is a therapeutic modality capable of inducing cell death by oxidative stress through activation of a sensitizer by light. Aryl-porphyrin with hydroxyl groups are good photosensitizers and presence of bromine atoms can enhance the photodynamic activity through heavy atom effect. These facts and our previous work made pertinent to compare the photodynamic capacity of tetraaryl brominated porphyrin (TBr4) with the corresponding diaryl (BBr2) derivative. Cell cultures were incubated with the sensitizers, ranging from 50nM to 10μM and irradiated until 10J. Cell proliferation was analysed by MTT assay. Flow cytometry studies evaluated cell death pathways, mitochondrial membrane potential and ROS. For in vivo studies Balb/c nu/nu mice were injected with 4×10(6)cells. After PDT, monitoring was carried out for 12 days to establish Kaplan-Meier survival curves. Tumours were excised and histological analysis was performed. Both sensitizers seem to accumulate in the mitochondria. The molecules have no intrinsic cytotoxicity or in non-tumour cells at therapeutic concentrations. Both sensitizers induced a significant decrease of cell proliferation and growth of xenografts of melanoma and colorectal adenocarcinoma. Diaryl BBr2 is more efficient than tetraaryl TBr4, concerning intracellular ROS production, mitochondrial disruption and induction of cell death. The main cell death pathway is necrosis. TBr2 and BBr4 are promising sensitizers with good photodynamic properties and have the ability to induce cell death in human melanoma and colorectal adenocarcinoma in vitro and in vivo. We consider that BBr2 is a molecule that should be the subject of extensive studies towards clinical use. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Photoactivation Studies of Zinc Porphyrin-Myoglobin System and Its Application for Light-Chemical Energy Conversion

    Science.gov (United States)

    Chang, Chin-Hao; Hu, Yi-Ting; Lo, Chen-Fu; Luo, Liyang; Lin, Hung-Ming; Chang, Cheng-Hsiang; Lin, Ching-Yao; Diau, Eric Wei-Guang; Wu, Tung-Kung

    2011-01-01

    An artificial zinc porphyrin-myoglobin-based photo-chemical energy conversion system, consisting of ZnPP-Mb or ZnPE1-Mb as a photosensitizer, NADP+ as an electron acceptor, and triethanolamine as an electron donor, has been constructed to mimic photosystem I. The photoirradiated product is able to reduce a single-electron acceptor protein cytochrome c, but cannot catalyze the two-electron reduction of acetaldehyde by alcohol dehydrogenase, thus demonstrating a single electron transfer mechanism. Furthermore, the artificial system can bifunctionally promote oxidoredox reactions, depending on the presence or absence of a sacrificial electron donor, thus suggesting its potential application in electrochemical regeneration steps involved in chemical transformation and/or energy conversion. PMID:22043177

  2. Structural features of vanadyl porphyrins of petroleum of West Kazakhstan

    Energy Technology Data Exchange (ETDEWEB)

    Bakirova, S.F.; Kotova, A.V.; Yag' yaeva, S.; Fedorova, N.V.; Nadirov, N.K.

    1984-01-01

    During the past 10 to 15 years studies have been published concerning petroleum porphyrins in which a description was given of the composition and structure of porphyrins of petroleums found in various regions abroad and in the Soviet Union - West Siberia, the Kama region, Tajikistan. Porphyrin structure has been established using electron and IR spectroscopy, nuclear and paramagnetic resonance, mass-spectrometry (low and high resolution), these techniques enabled the form of the main nucleus and its peripheral substituents to be established and yielded information concerning the molar mass values and the number of carbon atoms in alkyl chains. Methods developed in the Tomsk Institute of Petroleum Chemistry, USSR Academy of Sciences were used in this study, which involve the following operations: (1) extraction of porphyrins from petroleum using dimethylformamide; (2) chromatographic purification of the separated porphyrins elution from columns packed with aluminas of different activities by organic solvents and their mixtures, in order of increasing polarities; (3) mass-spectrometric examination of the purified vanadyl-porphyrin samples. The composition of porphyrins and the ratio of etioporphyrins and desoxophylloerythro-etioporphyrins was deduced from the electron spectra obtained from the purified porphyrin samples separated from petroleums.

  3. The composition of petroleum porphyrines from Western Kazakhstan

    Energy Technology Data Exchange (ETDEWEB)

    Bakirova, S.F.; Benkovskiy, V.G.; Kotova, A.V.; Serebrennikova, O.V.

    1984-01-01

    A high content of vanadium porphyrines in a number of oils, which is associated with their bedding conditions and the characteristics of the starting organic matter (OV) and is characteristic for oils from Western Kazakhstan, is noted. The molecular composition is studied of vanadyl porphyrines which were isolated from oils using extractive chromatographic methods and were studied using low resolution mass spectrometry (in a MAT-311 instrument) and through analytical fine layer chromatography. It is discovered that 90 to 95 percent of all the vanadyl porphyrines consist of homologs of ethioporphyrine (the M series) and desoxophylloerythroethioporphyrines (the M-2 series). Only in a single case (the Karazhanbas deposit) are there up to 30 percent compounds of the M-6 series. The ratio of M-2 to M and the content of nonpolar porphyrines (in percent), which are chromatographically identified, were used as the characteristics. The chromatographic mobility is basically determined by the molecular mass, that is, by the number of methylene groups in the lateral substituents of the porphyrine ring. A comparison of the number of nonpolar porphyrines with the oil bedding depth shows a regular increase in the volume of these compounds with a reduction in the bedding depth; the presence in the oil of less than 50 percent nonpolar porphyrines (the Pribrezhnyy, Severnyy Buzachi and Kalamkas deposits) and the absence of polar porphyrines confirms the assumption about the intermediate stage of the migratory path of the oil and about its flow from the deep layers into the overlying sediments of the persalt complex.

  4. The effects of urea, guanidinium chloride and sorbitol on porphyrin ...

    Indian Academy of Sciences (India)

    This paper compares the inhibition effect of porphyrin aggregation in the presence of urea, guanidinium chloride (Gdn) and sorbitol by molecular dynamics simulation. It demonstrates that porphyrin aggregation increases in sorbitol, but decreases towards addition of urea and Gdn. It shows that urea, Gdn and sorbitol can ...

  5. Functionalized zinc porphyrin as light harvester in dye sensitized ...

    Indian Academy of Sciences (India)

    Wintec

    2008-09-10

    Sep 10, 2008 ... Functionalized zinc porphyrin as light harvester in dye sensitized solar cells. L GIRIBABU, a,. * CH VIJAY KUMAR, ... In contrast, given their primary role in natural photosynthesis, the use of porphyrins as light har- ... NiO, ZnO and TiO2, the most common being the free-base and zinc derivatives of the meso- ...

  6. Porphyrin architectures tailored for studies of molecular information storage.

    Science.gov (United States)

    Carcel, Carole M; Laha, Joydev K; Loewe, Robert S; Thamyongkit, Patchanita; Schweikart, Karl-Heinz; Misra, Veena; Bocian, David F; Lindsey, Jonathan S

    2004-10-01

    A molecular approach to information storage employs redox-active molecules tethered to an electroactive surface. Zinc porphyrins tethered to Au(111) or Si(100) provide a benchmark for studies of information storage. Three sets of porphyrins have been synthesized for studies of the interplay of molecular design and charge-storage properties: (1) A set of porphyrins is described for probing the effect of surface attachment atom on electron-transfer kinetics. Each porphyrin bears a meso-CH2X group for surface attachment where X = OH, SAc, or SeAc. (2) A set of porphyrins is described for studying the effect of surface-charge density in monolayers. Each porphyrin bears a benzyl alcohol for surface attachment and three nonlinking meso substituents of a controlled degree of bulkiness. (3) A set of porphyrins is described that enables investigation of on-chip patterning of the electrolyte. Each porphyrin bears a formyl group distal to the surface attachment group for subsequent derivatization with a molecular entity that comprises the electrolyte. Taken together, this collection of molecules enables a variety of studies to elucidate design issues in molecular-based information storage. Copyright 2004 American Chemical Society

  7. Reactions of iron(III) porphyrins with peroxides and hydrogen ...

    Indian Academy of Sciences (India)

    Administrator

    Reactions of iron(III) porphyrins with peroxides and hydrogen peroxide: Mechanistic insights. PARVESH WADHWANI and DEBKUMAR BANDYOPADHYAY. Department of Chemistry, Indian Institute of Technology,. New Delhi 110 016, India. Iron(III) porphyrin catalysed oxidations of different substrates by hydroperoxides ...

  8. Pulverization of boron element and proportions of boron carbide in boron

    International Nuclear Information System (INIS)

    Lang, F.M.; Finck, C.

    1956-01-01

    It is possible to reduce boron element into fine powder by means of a mortar and pestle made of sintered boron carbide, the ratio of boron carbide introduced being less than one per cent. Boron element at our disposal is made of sharp edged, dark brown, little grains of average size greater than 5 μ. Grain sizes smaller than 1μ are required for applying thin layers of such boron. (author) [fr

  9. Corroles-Porphyrins: A Teamwork for Gas Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Rosamaria Capuano

    2015-04-01

    Full Text Available Porphyrins provide an excellent material for chemical sensors, and they have been used for sensing species both in air and solution. In the gas phase, the broad selectivity of porphyrins is largely dependant on molecular features, such as the metal ion complexed at the core of the aromatic ring and the peripheral substituents. Although these features have been largely exploited to design gas sensor arrays, so far, little attention has been devoted to modify the sensing properties of these macrocycles by variation of the molecular aromatic ring. In this paper, the gas sensing properties of a porphyrin analog, the corrole, are studied in comparison with those of the parent porphyrin. Results show that changes in the aromatic ring have important consequences on the sensitivity and selectivity of the sensors and that porphyrins and corroles can positively cooperate to enhance the performance of sensor arrays.

  10. Corroles-porphyrins: a teamwork for gas sensor arrays.

    Science.gov (United States)

    Capuano, Rosamaria; Pomarico, Giuseppe; Paolesse, Roberto; Di Natale, Corrado

    2015-04-08

    Porphyrins provide an excellent material for chemical sensors, and they have been used for sensing species both in air and solution. In the gas phase, the broad selectivity of porphyrins is largely dependant on molecular features, such as the metal ion complexed at the core of the aromatic ring and the peripheral substituents. Although these features have been largely exploited to design gas sensor arrays, so far, little attention has been devoted to modify the sensing properties of these macrocycles by variation of the molecular aromatic ring. In this paper, the gas sensing properties of a porphyrin analog, the corrole, are studied in comparison with those of the parent porphyrin. Results show that changes in the aromatic ring have important consequences on the sensitivity and selectivity of the sensors and that porphyrins and corroles can positively cooperate to enhance the performance of sensor arrays.

  11. Surface Morphology and Optical Properties of 3 Porphyrin/Au and Au/Porphyrin/Au Systems

    Czech Academy of Sciences Publication Activity Database

    Kalachyova, Y.; Lyutakov, O.; Solovyev, Andrey; Slepička, P.; Švorčík, V.

    2013-01-01

    Roč. 8, DEC 27 (2013), s. 547 ISSN 1931-7573 Grant - others:GA ČR(CZ) GPP108/11/P840; GA ČR(CZ) GAP108/12/1168 Program:GA Institutional support: RVO:67985858 Keywords : nanostructures * gold * porphyrin * luminescence * enhancement * surface morphology Subject RIV: JJ - Other Materials Impact factor: 2.524, year: 2012

  12. Application of the boron neutron capture therapy to undifferentiated thyroid cancer using two boron compounds (BPA and BOPP)

    International Nuclear Information System (INIS)

    Viaggi, Mabel; Dagrosa, Maria A.; Juvenal, Guillermo J.; Pisarev, Mario A.; Longhino, Juan M.; Blaumann, Hernan R.; Calzetta Larrieu, Osvaldo A.; Kahl, Stephen B.

    2004-01-01

    We have shown the selective uptake of boronophenylalanine (BPA) by undifferentiated thyroid cancer (UTC) human cell line ARO, both in vitro and in vivo. Moreover, a 50% histologic cure of mice bearing the tumor was observed when the complete boron neutron capture therapy was applied. More recently we have analyzed the biodistribution of BOPP (tetrakis-carborane carboxylate ester of 2,4-bis-(ba-dihydroxyethyl)-deutero-porphyrin IX) and showed that when BOPP was injected 5 days before BPA, and the animals were sacrificed 60 min after the ip injection of BPA, a significant increase in boron uptake by the tumor was found (38-45ppm with both compounds Vs. 20 ppm with BPA alone). Five days post the ip BOPP injection and 1 hr after BPA, the ratios were: tumor/blood 3,75; tumor /distal skin 2. Other important ratios were tumor/thyroid 6,65 and tumor/lung 3,8. The present studies were performed in mice transplanted with ARO cells and injected with BOPP and BPA. Only in mice treated with the neutron beam and injected with the boronated compounds we observed a 100% control of tumor growth. Two groups of mice received different total absorbed doses: 3.00 and 6.01 Gy, but no further improvement in the outcome was found compared to the previous results using BPA alone (4.3 Gy). (author)

  13. Effect of porphyrin on photocatalytic activity of TiO2 nanoparticles toward Rhodamine B photodegradation.

    Science.gov (United States)

    Ahmed, M A; Abou-Gamra, Z M; Medien, H A A; Hamza, M A

    2017-11-01

    As known, porphyrins have central role in photosynthesis, biological oxidation and reduction and oxygen transport beside to their intensive color which qualify them to be good photosensitizers. Herein, tetra (4-carboxyphenyl) porphyrin (TCPP) was prepared by a simple one-pot synthesis to use as a visible antenna for TiO 2 nanoparticles that were prepared via a simple template-free sol-gel method. Various loading percentages of TCPP (0.05-1%) were incorporated on the surface of TiO 2 as photosensitizer for photocatalytic degradation of Rhodamine B (Rh B) dye as a primary cationic pollutant model. Among them, 0.1% TCPP-TiO 2 was the most reactive sample. It was found that the photoactivity of 0.1% TCPP-TiO 2 sample (0.5g/L) was approximately 1.5 times greater than that of pure TiO 2 (0.5g/L) toward the degradation of Rh B (1×10 -5 M) under UV-A irradiation. Transient fluorescence decay measurements showed that the life time of TiO 2 excited state has doubled after anchoring TCPP, thus the probability of electron-hole recombination has decreased. The samples were characterized by XRD, HR-TEM, DRS and N 2 adsorption-desorption isotherms. The XRD patterns confirmed the successful preparation of TiO 2 nanoparticles with average crystalline size of 25.7nm. Also, XRD patterns suggested the presence of mixed phase TiO 2 nanoparticles of 77% anatase and 23% rutile. DRS showed that the characteristic peaks of TCPP covered the whole visible range 400-700nm. HR-TEM images showed the spheroids shape of TiO 2 nanoparticles and confirmed the presence of anatase and rutile phases as suggested from XRD data. The different parameters affecting the photodegradation of Rh B dye such as catalyst dose, dye concentration and pH were studied to obtain the optimum conditions. Almost complete degradation of Rh B was obtained which confirmed by HPLC and TOC measurements. The effect of scavengers was studied to indicate the most active species. TCPP-TiO 2 gave a good response toward the

  14. Structurally homologous beta- and meso-alkynyl amidinium porphyrins.

    Science.gov (United States)

    Rosenthal, Joel; Young, Elizabeth R; Nocera, Daniel G

    2007-10-15

    Alkynylamidinium groups have been introduced at the beta and meso positions of a nickel(II) porphyrin (PNi(II)) framework. The modification permits the distance between the amidinium-amidine acid-base group and porphyrin to be increased while effectively maintaining pi conjugation between the porphyrin macrocycle and the acid-base functionality. Use of an ethynyl spacer as a linker (i) extends the amidinium functionality away from the sterically bulky mesityl groups of the porphyrin, allowing it to be nearly planar with respect to the porphyrin ring, and (ii) draws the pi-orbital character of the porphyrin out toward the amidinium functionality, thereby engendering sensitivity of the electronic properties of the porphyrin macrocycle to the protonation state of the amidinium. The barrier for rotation of the amidinium group, as calculated by time-dependent density functional theory (TDDFT), is approximately 8.5 kT (5 kcal/mol) for both porphyrins. Analysis of UV-visible absorption profiles for the beta- and meso-alkynylamidinium PNi(II) upon deprotonation enables accurate determination of the amidinium acidity constants for the ground state (pK(a)(beta) = 7.03 +/- 0.1, pK(a)(meso) = 7.74 +/- 0.1 in CH(3)CN) and excited state (pK(a)*(beta) = 6.89 +/- 0.1, pK(a)*(meso) = 8.37 +/- 0.1 in CH(3)CN) porphyrins. Whereas pK(a)* pK(a) for the meso-alkynylamidinium porphyrin, indicating that beta-alkynylamidinium PNi(II) is a photoacid and meso-alkynylamidinium PNi(II) is a photobase. These divergent behaviors are supported by analysis of the frontier molecular orbitals of the homologous pair with TDDFT.

  15. Highly Effective Dual-Function Near-Infrared (NIR) Photosensitizer for Fluorescence Imaging and Photodynamic Therapy (PDT) of Cancer.

    Science.gov (United States)

    Patel, Nayan; Pera, Paula; Joshi, Penny; Dukh, Mykhaylo; Tabaczynski, Walter A; Siters, Kevin E; Kryman, Mark; Cheruku, Ravindra R; Durrani, Farukh; Missert, Joseph R; Watson, Ramona; Ohulchanskyy, Tymish Y; Tracy, Erin C; Baumann, Heinz; Pandey, Ravindra K

    2016-11-10

    We report herein the synthesis and biological efficacy of near-infrared (NIR), bacteriochlorin analogues: 3-(1'-butyloxy)ethyl-3-deacetyl-bacteriopurpurin-18-N-butylimide methyl ester (3) and the corresponding carboxylic acid 10. In in vitro assays, compared to its methyl ester analogue 3, the corresponding carboxylic acid derivative 10 showed higher photosensitizing efficacy. However, due to drastically different pharmacokinetics in vivo, the PS 3 (HPLC purity >99%) showed higher tumor uptake and long-term tumor cure than 10 (HPLC purity >96.5%) in BALB/c mice bearing Colon 26 tumors. Isomerically pure R- and S- isomers of 3 (3a and 3b, purity by HPLC > 99%) under similar treatment parameters showed identical efficacy in vitro and in vivo. In addition, photosensitizer (PS) 3 showed limited skin phototoxicity and provides an additional advantage over the clinically approved chemically complex hematoporphyrin derivative as well as other porphyrin-based PDT agents, which makes 3 a promising dual-function agent for fluorescence-guided surgery with an option of phototherapy of cancer.

  16. Acid-catalyzed disproportionation of oxoiron(IV) porphyrins to give oxoiron(IV) porphyrin radical cations.

    Science.gov (United States)

    Pan, Zhengzheng; Newcomb, Martin

    2011-06-01

    Disproportionation of oxoiron(IV) porphyrin (Compound II) to oxoiron(IV) porphyrin radical cation (Compound I) was studied in three P450 model systems with different electronic structures. Direct conversion of Compound II to Compound I has been observed for 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin (TDCPP) in acid-catalyzed reactions in a mixed solvent of acetonitrile and water (1:1, v/v) containing excess m-CPBA oxidant, with a second-order rate constant of (1.3 ± 0.2) × 10(2) M(-1) s(-1). The acid-catalyzed disproportionation heavily depends on the electron demand of the substituted aryl groups on the porphyrin macrocycle. The disproportionation equilibrium constants show drastic change for the three porphyrin systems.

  17. Elsinochrome A photosensitizers: Alternative drugs for photodynamic therapy

    Directory of Open Access Journals (Sweden)

    Tinghui Li

    2015-01-01

    Full Text Available Photodynamic therapy (PDT has already been a multifunctional modality for various tumors and nontumorous diseases. However, the development of photosensitizers is relatively delayed, compared with the tremendous progress in laser technology. Elsinochrome A (EA, a perylenequinonoid pigment from China, has all the typical advantages of perylenequinones. Moreover, singlet oxygen quantum yield of EA is superior to other kinds of photosensitizers and EA could be artificially biosynthesized at present, which make it an alternative candidate for PDT. In this review, the photophysics, photochemistry, photobiology and chemical or biological syntheses of EA photosensitizers are briefly presented. Besides, the future prospects of EA photosensitizers are also proposed.

  18. Porphyrin-magnetite nanoconjugates for biological imaging

    LENUS (Irish Health Repository)

    Nowostawska, Malgorzata

    2011-04-08

    Abstract Background The use of silica coated magnetic nanoparticles as contrast agents has resulted in the production of highly stable, non-toxic solutions that can be manipulated via an external magnetic field. As a result, the interaction of these nanocomposites with cells is of vital importance in understanding their behaviour and biocompatibility. Here we report the preparation, characterisation and potential application of new "two-in-one" magnetic fluorescent nanocomposites composed of silica-coated magnetite nanoparticles covalently linked to a porphyrin moiety. Method The experiments were performed by administering porphyrin functionalised silica-coated magnetite nanoparticles to THP-1 cells, a human acute monocytic leukaemia cell line. Cells were cultured in RPMI 1640 medium with 25 mM HEPES supplemented with heat-inactivated foetal bovine serum (FBS). Results We have synthesised, characterised and analysed in vitro, a new multimodal (magnetic and fluorescent) porphyrin magnetic nanoparticle composite (PMNC). Initial co-incubation experiments performed with THP-1 macrophage cells were promising; however the PMNC photobleached under confocal microscopy study. β-mercaptoethanol (β-ME) was employed to counteract this problem and resulted not only in enhanced fluorescence emission, but also allowed for elongated imaging and increased exposure times of the PMNC in a cellular environment. Conclusion Our experiments have demonstrated that β-ME visibly enhances the emission intensity. No deleterious effects to the cells were witnessed upon co-incubation with β-ME alone and no increases in background fluorescence were recorded. These results should present an interest for further development of in vitro biological imaging techniques.

  19. Porphyrin-magnetite nanoconjugates for biological imaging

    Directory of Open Access Journals (Sweden)

    Conroy Jennifer

    2011-04-01

    Full Text Available Abstract Background The use of silica coated magnetic nanoparticles as contrast agents has resulted in the production of highly stable, non-toxic solutions that can be manipulated via an external magnetic field. As a result, the interaction of these nanocomposites with cells is of vital importance in understanding their behaviour and biocompatibility. Here we report the preparation, characterisation and potential application of new "two-in-one" magnetic fluorescent nanocomposites composed of silica-coated magnetite nanoparticles covalently linked to a porphyrin moiety. Method The experiments were performed by administering porphyrin functionalised silica-coated magnetite nanoparticles to THP-1 cells, a human acute monocytic leukaemia cell line. Cells were cultured in RPMI 1640 medium with 25 mM HEPES supplemented with heat-inactivated foetal bovine serum (FBS. Results We have synthesised, characterised and analysed in vitro, a new multimodal (magnetic and fluorescent porphyrin magnetic nanoparticle composite (PMNC. Initial co-incubation experiments performed with THP-1 macrophage cells were promising; however the PMNC photobleached under confocal microscopy study. β-mercaptoethanol (β-ME was employed to counteract this problem and resulted not only in enhanced fluorescence emission, but also allowed for elongated imaging and increased exposure times of the PMNC in a cellular environment. Conclusion Our experiments have demonstrated that β-ME visibly enhances the emission intensity. No deleterious effects to the cells were witnessed upon co-incubation with β-ME alone and no increases in background fluorescence were recorded. These results should present an interest for further development of in vitro biological imaging techniques.

  20. Porphyrin Protonation Studied by Magnetic Circular Dichroism

    Czech Academy of Sciences Publication Activity Database

    Štěpánek, Petr; Andrushchenko, Valery; Ruud, K.; Bouř, Petr

    2012-01-01

    Roč. 116, č. 1 (2012), s. 778-783 ISSN 1089-5639 R&D Projects: GA ČR GAP208/11/0105; GA ČR GA203/09/2037; GA ČR GAP208/10/0559; GA MŠk(CZ) LH11033 Institutional research plan: CEZ:AV0Z40550506 Keywords : magnetic circular dichroism (MCD) * TPPS * spectra simulations * porphyrin protonation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.771, year: 2012

  1. Photoprocesses of photosensitizing drugs within cyclodextrin cavities.

    Science.gov (United States)

    Monti, Sandra; Sortino, Salvatore

    2002-09-01

    Recently some interest has been focused on the photobehavior of CD-drug inclusion complexes in relation to the problem of the biological photosensitization by drugs. This review is dedicated to the illustration of the mechanistic aspects of the photoprocesses occurring in some non-steroidal anti-inflammatory drugs (NSAIDs), with photosensitising side effects, within CD cavities. It is shown how the photobehavior of the CD-drug associates can help to model the photoreactivity of the drugs in biological sites. The limitations for the use of CDs as protective systems for the clinical administration of photosensitising drugs is also evidenced.

  2. Phototherapeutic, photobiologic, and photosensitizing properties of khellin

    Energy Technology Data Exchange (ETDEWEB)

    Morliere, P.; Hoenigsmann, H.A.; Averbeck, D.; Dardalhon, M.; Hueppe, G.O.; Ortel, B.; Santus, R.; Dubertret, L.

    1988-05-01

    Khellin, whose chemical structure closely resembles that of psoralen, is reported to be an efficient drug for treating vitiligo when combined with ultraviolet A irradiation. Photobiological activity on yeast is found to be much lower than that of bifunctional psoralens such as 5-methoxypsoralen. In vitro experiments reveal that khellin is a poor photosensitizer. It behaves as a monofunctional agent with respect to DNA photoaddition. It does not photoinduce cross-links in DNA in vitro or in Chinese hamster cells in vivo. This behavior may explain the low photogenotoxicity in yeast and the lack of phototoxic erythemal response when treating vitiligo with khellin.

  3. Application of fluorescence spectroscopy and imaging in the detection of a photosensitizer in photodynamic therapy

    Science.gov (United States)

    Zang, Lixin; Zhao, Huimin; Zhang, Zhiguo; Cao, Wenwu

    2017-02-01

    Photodynamic therapy (PDT) is currently an advanced optical technology in medical applications. However, the application of PDT is limited by the detection of photosensitizers. This work focuses on the application of fluorescence spectroscopy and imaging in the detection of an effective photosenzitizer, hematoporphyrin monomethyl ether (HMME). Optical properties of HMME were measured and analyzed based on its absorption and fluorescence spectra. The production mechanism of its fluorescence emission was analyzed. The detection device for HMME based on fluorescence spectroscopy was designed. Ratiometric method was applied to eliminate the influence of intensity change of excitation sources, fluctuates of excitation sources and photo detectors, and background emissions. The detection limit of this device is 6 μg/L, and it was successfully applied to the diagnosis of the metabolism of HMME in the esophageal cancer cells. To overcome the limitation of the point measurement using fluorescence spectroscopy, a two-dimensional (2D) fluorescence imaging system was established. The algorithm of the 2D fluorescence imaging system is deduced according to the fluorescence ratiometric method using bandpass filters. The method of multiple pixel point addition (MPPA) was used to eliminate fluctuates of signals. Using the method of MPPA, SNR was improved by about 30 times. The detection limit of this imaging system is 1.9 μg/L. Our systems can be used in the detection of porphyrins to improve the PDT effect.

  4. Porphyrin Interactions with Wild Type and Mutant Mouse Ferrochelatase

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Gloria C.; Franco, Ricardo; Lu, Yi; Ma, Jian-Guo; Shelnutt, John A.

    1999-05-19

    Ferrochelatase (EC 4.99.1.1), the terminal enzyme of the heme biosynthetic pathway, catalyzes Fe2+ chelation into protoporphyrin IX. Resonance Raman and W-visible absorbance spectroscopes of wild type and engineered variants of murine ferrochelatase were used to examine the proposed structural mechanism for iron insertion into protoporphyrin by ferrochelatase. The recombinant variants (i.e., H207N and E287Q) are enzymes in which the conserved amino acids histidine-207 and glutamate-287 of murine ferrochelatase were substituted with asparagine and glutamine, respectively. Both of these residues are at the active site of the enzyme as deduced from the Bacillus subtilis ferrochelatase three-dimensional structure. Addition of free base or metalated porphyrins to wild type ferrochelatase and H207N variant yields a quasi 1:1 complex, possibly a monomeric protein-bound species. In contrast, the addition of porphyrin (either free base or metalated) to E287Q is sub-stoichiometric, as this variant retains bound porphyrin in the active site during isolation and purification. The specificity of porphyrin binding is confirmed by the narrowing of the structure-sensitive resonance Raman lines and the vinyl vibrational mode. Resonance Raman spectra of free base and metalated porphyrins bound to the wild type ferrochelatase indicate a nonplanar distortion of the porphyrin macrocycle, although the magnitude of the distortion cannot be determined without first defining the specific type of deformation. Significantly, the extent of the nonplanar distortion varies in the case of H207N- and E287Q-bound porphyrins. In fact, resonance Raman spectral decomposition indicates a homogeneous ruffled distortion for the nickel protoporphyrin bound to the wild type ferrochelatase, whereas both a planar and ruffled conformations are present for the H207N-bound porphyrin. Perhaps more revealing is the unusual resonance , 3 Raman spectrum of the endogenous E287Q-bound porphyrin, which has

  5. Boronated liposome development and evaluation

    International Nuclear Information System (INIS)

    Hawthorne, M.F.

    1995-01-01

    The boronated liposome development and evaluation effort consists of two separate tasks. The first is the development of new boron compounds and the synthesis of known boron species with BNCT potential. These compounds are then encapsulated within liposomes for the second task, biodistribution testing in tumor-bearing mice, which examines the potential for the liposomes and their contents to concentrate boron in cancerous tissues

  6. Nanobody-photosensitizer conjugates for targeted photodynamic therapy

    NARCIS (Netherlands)

    Heukers, Raimond; van Bergen en Henegouwen, P; Oliveira, Sabrina

    2014-01-01

    Photodynamic therapy (PDT) induces cell death through light activation of a photosensitizer (PS). Targeted delivery of PS via monoclonal antibodies has improved tumor selectivity. However, these conjugates have long half-lives, leading to relatively long photosensitivity in patients. In an attempt

  7. Photosensitive disorders in HIV | Koch | Southern African Journal of ...

    African Journals Online (AJOL)

    Photosensitive disorders are common, affecting up to 5% of HIV-positive patients. HIV itself induces photosensitivity but photoaggravated drug reactions, porphyria cutanea tarda and nutritional disorders such as pellagra are also more common in patients with HIV. In South Africa, actinic lichenoid leukomelanoderma of HIV ...

  8. A near-infrared genetically targetable and activatable photosensitizer

    Science.gov (United States)

    He, Jianjun; Wang, Yi; Missinato, Maria A.; Onuoha, Ezenwa; Perkins, Lydia A.; Watkins, Simon C.; St. Croix, Claudette M.; Tsang, Michael; Bruchez, Marcel P.

    2016-01-01

    Upon illumination, photosensitizer molecules produce reactive oxygen species (ROS) that can be utilized for functional manipulation of living cells, including protein inactivation, targeted damage introduction, and cellular ablation. Photosensitizers used to date have been either exogenous, resulting in delivery and removal challenges, or genetically encoded proteins that form or bind a native photosensitizing molecule, resulting in a constitutively active photosensitizer inside the cell. By binding a heavy-atom substituted fluorogenic dye with a genetically encoded Fluorogen Activating Protein (FAP), we demonstrate an ‘on-demand’ activated photosensitizer that produces singlet oxygen and fluorescence only when FAP-bound and activated with near infrared light. This Targeted and Activated Photosensitizer (TAPs) approach enables protein inactivation and targeted cell killing in cultured cells and rapid targeted lineage ablation in living larval and adult zebrafish. The near-infrared excitation and emission of this FAP-TAPs photosensitizer module provides a new spectral range for photosensitizer proteins, useful for imaging, manipulation and cellular ablation deep within living organisms. PMID:26808669

  9. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    mental phase contrast images and the diffraction pattern. Figure 3. (a) Bright field image of electrodeposited boron spec- imen showing a crystallite of size ∼10 × 5 nm; (b) phase contrast image of electrodeposited boron specimen showing a resolved la- ttice and (c) power spectrum of electrodeposited boron specimen.

  10. Photosensitizing compounds in the treatment of psoriasis.

    Science.gov (United States)

    Hönigsmann, H; Tanew, A; Brücke, J; Ortel, B

    1989-01-01

    Photosensitizers were first used to treat psoriasis 15 years ago when the phototoxic reaction of psoralens and UVA was found to induce remissions of the disease. The effect of this reaction on DNA, particularly the formation of cross-links, was thought to be the decisive event. Strong cross-linking agents such as 8-MOP, TMP and 5-MOP are clinically effective whereas most compounds which produce only monofunctional adducts are virtually ineffective. Orally administered 8-methoxypsoralen (8-MOP) is the most widely used compound. 4,5',8-Trimethylpsoralen (TMP) is poorly absorbed from the intestine but has marked efficacy when applied topically. 5-MOP may be a useful alternative to 8-MOP because it is less erythemogenic and does not cause nausea. These three furocoumarins appear to be similar photochemically and may introduce similar risks. However, the photobiological properties of furocoumarins can be modified by altering one or more parts of the molecule. Such modifications might yield effective analogues with reduced cytogenetic hazards. Several psoralens and angular furocoumarins are being tested for effectiveness combined with fewest long-term side-effects, especially carcinogenesis. Encouraging preliminary results have been obtained with 7-methyl-pyridopsoralen and 4,6,4'-trimethylangelicin. Other important approaches to increasing the safety of photochemotherapy may be the use of different photoactivating wavelengths or the introduction of new classes of photosensitizers.

  11. Intermolecular Structural Change for Thermoswitchable Polymeric Photosensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Park, Wooram; Park, Sin-Jung [Center; Cho, Soojeong; Shin, Heejun [Center; Jung, Young-Seok [Center; Lee, Byeongdu [X-ray; Na, Kun [Center; Kim, Dong-Hyun

    2016-08-17

    A switchable photosensitizer (PS), which can be activated at a spe-cific condition beside light, has tremendous advantages for photo-dynamic therapy (PDT). Herein, we developed a thermo-switchable polymeric photosensitizer (T-PPS) by conjugating PS (Pheophor-bide-a, PPb-a) to a temperature-responsive polymer backbone of biocompatible hydroxypropyl cellulose (HPC). Self-quenched PS molecules linked in close proximity by pi-pi stacking in T-PPS were easily transited to an active monomeric state by the tempera-ture induced phase transition of polymer backbones. The tempera-ture responsive inter-molecular interaction changes of PS molecules in T-PPS were demonstrated in synchrotron small-angle X-ray scattering (SAXS) and UV-Vis spectrophotometer analysis. The T-PPS allowed switchable activation and synergistically enhanced cancer cell killing effect at the hyperthermia temperature (45 °C). Our developed T-PPS has the considerable potential not only as a new class of photomedicine in clinics but also as a biosensor based on temperature responsiveness.

  12. Photo-activated porphyrin in combination with antibiotics: therapies against Staphylococci

    Science.gov (United States)

    Dastgheyb, Sana S.; Eckmann, David M.; Composto, Russell J.

    2013-01-01

    Staphylococcal infections have become difficult to treat due to antibiotic insensitivity and resistance. Antimicrobial combination therapies may minimize acquisition of resistance and photodynamic therapy is an attractive candidate for these combinations. In this manuscript, we explore combined use of antibiotics and meso-tetra (4-aminophenyl) porphine (TAPP), a cationic porphyrin, for treatment of Staphylococcus aureus contamination. We characterize the antimicrobial activity of photoactivated TAPP and show that activity is largely lost in the presence of a radical scavenger. Importantly, TAPP can be reactivated with continued, albeit attenuated, antibacterial activity. We then show that the antimicrobial activity of illuminated TAPP is additive with chloramphenicol and tobramycin for Staphylococcus aureus and Escherichia coli, and synergistic for MRSA and Staphylococcus epidermidis. Chloramphenicol + methylene blue, another photosensitizer, also show additivity against Staphylococcus aureus. In contrast, ceftriaxone and vancomycin do not strongly augment the low level effects of TAPP against S. aureus. Eukaryotic cells exhibit a dose-dependent toxicity with illuminated TAPP. Our results suggest that even sub-minimum inhibitory concentration levels of photo-activated TAPP could be used to boost the activity of waning antibiotics. This may play an important role in treatments reliant on antibiotic controlled release systems where augmentation with photo-active agents could extend their efficacy. PMID:24148969

  13. Enrichment of boron 10

    International Nuclear Information System (INIS)

    Coutinho, C.M.M.; Rodrigues Filho, J.S.R.; Umeda, K.; Echternacht, M.V.

    1990-01-01

    A isotopic separation pilot plant with five ion exchange columns interconnected in series were designed and built in the IEN. The columns are charged with a strong anionic resin in its alkaline form. The boric acid solution is introduced in the separation columns until it reaches a absorbing zone length which is sufficient to obtain the desired boron-10 isotopic concentration. The boric acid absorbing zone movement is provided by the injection of a diluted hydrochloric acid solution, which replace the boric acid throughout the columns. The absorbing zone equilibrium length is proportional to its total length. The enriched boron-10 and the depleted boron are located in the final boundary and in the initial position of the absorbing zones, respectively. (author)

  14. Electrocatalysis of Oxygen Using Water Soluble Metal Porphyrins and Chemically Modified Porphyrin Electrodes.

    Science.gov (United States)

    1983-11-01

    important to model the proposed mechanism for oxygen electrocatalysis and to computer simulate the electrochemical response characteristics and compare...m .S " 3 -1 9 7 .8NOV W3 RF Project 761254/711380 Final Report ELECTROCATALYSIS OF OXYGEN * AND USING WATER SOLUBLE METAL...cobalt porphyrins, namely, iron and cobalt tetrakis(N-methyl- 4-pyridyllpcrphyrin. These prophyrins with the metal in the +3 oxidation state can be

  15. In Vivo Boron Uptake Determination for Boron Neutron Capture Synovectomy

    Energy Technology Data Exchange (ETDEWEB)

    Binello, Emanuela; Shortkroff, Sonya; Yanch, Jacquelyn C.

    1999-06-06

    Boron neutron capture synovectomy (BNCS) has been proposed as a new application of the boron neutron capture reaction for the treatment of rheumatoid arthritis. In BNCS, a boron compound is injected into the joint space, where it is taken up by the synovium. The joint is then irradiated with neutrons of a desired energy range, inducing the boron neutron capture reaction in boron-loaded cells. Boron uptake by the synovium is an important parameter in the assessment of the potential of BNCS and in the determination of whether to proceed to animal irradiations for the testing of therapeutic efficacy. We present results from an investigation of boron uptake in vivo by the synovium.

  16. Mineralogy of halloysites and their interaction with porphyrine

    Czech Academy of Sciences Publication Activity Database

    Vašutová, V.; Bezdička, Petr; Lang, Kamil; Hradil, David

    2013-01-01

    Roč. 57, č. 3 (2013), s. 243-250 ISSN 0862-5468 Institutional support: RVO:61388980 Keywords : organoclays * mineralogy * porphyrine * CEC Subject RIV: CA - Inorganic Chemistry Impact factor: 0.434, year: 2013

  17. Challenging Density Functional Theory Calculations with Hemes and Porphyrins

    Directory of Open Access Journals (Sweden)

    Sam P. de Visser

    2016-04-01

    Full Text Available In this paper we review recent advances in computational chemistry and specifically focus on the chemical description of heme proteins and synthetic porphyrins that act as both mimics of natural processes and technological uses. These are challenging biochemical systems involved in electron transfer as well as biocatalysis processes. In recent years computational tools have improved considerably and now can reproduce experimental spectroscopic and reactivity studies within a reasonable error margin (several kcal·mol−1. This paper gives recent examples from our groups, where we investigated heme and synthetic metal-porphyrin systems. The four case studies highlight how computational modelling can correctly reproduce experimental product distributions, predicted reactivity trends and guide interpretation of electronic structures of complex systems. The case studies focus on the calculations of a variety of spectroscopic features of porphyrins and show how computational modelling gives important insight that explains the experimental spectra and can lead to the design of porphyrins with tuned properties.

  18. Porphyrin Diacid-Polyelectrolyte Assemblies: Effective Photocatalysts in Solution

    Directory of Open Access Journals (Sweden)

    Sabine Frühbeißer

    2016-05-01

    Full Text Available Developing effective and versatile photocatalytic systems is of great potential in solar energy conversion. Here we investigate the formation of supramolecular catalysts by electrostatic self-assembly in aqueous solution: Combining positively charged porphyrins with negatively charged polyelectrolytes leads to nanoscale assemblies where, next to electrostatic interactions, π–π interactions also play an important role. Porphyrin diacid-polyelectrolyte assemblies exhibit a substantially enhanced catalytic activity for the light-driven oxidation of iodide. Aggregates with the hexavalent cationic porphyrin diacids show up to 22 times higher catalytic activity than the corresponding aggregates under neutral conditions. The catalytic activity can be increased by increasing the valency of the porphyrin and by choice of the loading ratio. The structural investigation of the supramolecular catalysts took place via atomic force microscopy and small angle neutron scattering. Hence, a new facile concept for the design of efficient and tunable self-assembled photocatalysts is presented.

  19. Porphyrin Diacid-Polyelectrolyte Assemblies: Effective Photocatalysts in Solution

    OpenAIRE

    Sabine Frühbeißer; Giacomo Mariani; Franziska Gröhn

    2016-01-01

    Developing effective and versatile photocatalytic systems is of great potential in solar energy conversion. Here we investigate the formation of supramolecular catalysts by electrostatic self-assembly in aqueous solution: Combining positively charged porphyrins with negatively charged polyelectrolytes leads to nanoscale assemblies where, next to electrostatic interactions, π–π interactions also play an important role. Porphyrin diacid-polyelectrolyte assemblies exhibit a substantially enhance...

  20. Resonance Raman study on distorted symmetry of porphyrin in ...

    Indian Academy of Sciences (India)

    plants [32]. They form important chromphores in haeme protein, chlorophylls, cytochrome oxidase etc. Nickel ocatethyl porphyrin, Ni(OEP), plays a central role in studies of the molec- ular properties of porphyrins ..... may attain any one of these, viz., D4, D2d, C4h, C4h, D2h, C4, S4, D2, C2v, C2h,. C2, Cs, Ci and C1 distorted ...

  1. Tetrakis(4-tert-butylphenyl) substituted and fused quinoidal porphyrins

    KAUST Repository

    Zeng, Wangdong

    2012-01-01

    4-tert-Butylphenyl-substituted and fused quinoidal porphyrins 1 and 2 are prepared for the first time. They show (1) intense one-photon absorption in the far-red/near-infrared region, (2) enhanced two-photon absorption compared with aromatic porphyrin monomers, and (3) amphoteric redox behavior. Their geometry and electronic structure are studied by DFT calculations. This journal is © 2012 The Royal Society of Chemistry.

  2. Investigation of the porphyrine role at the mechanism of radioprotection

    International Nuclear Information System (INIS)

    Demoukhamedova, S.D.; Alieva, I.N.; Aliev, D.I.

    2002-01-01

    Full text: To date, it is well known that unfavourable radioecological conditions capable effect on the oxygen transport system in an living organism, particularly, on the conformational state of hemoglobin. Underlying mechanism is more active autoxidation of Hb(O 2 )4 into met-hemoglobin. Decreasing of the oxygen binding to the heme group of protein as a result of modified effect of ionization was observed into peripheral blood of people living on the polluted territory. Porphyrin, the main component of hemoglobin has been showed a wide range radioprotector properties. So, the conformational reorganization of the porphyrin ring plays an important role at the mechanism of hemoglobin functioning. In this report the result of conformational study, quantum-chemical calculations and theoretical calculation of frequencies and intensities of normal oscillations of IR-absorption spectrum of the porphyrin molecule at the NO-binding are presented. Computational program 'LEV' was used in all carried calculations. Due to changes into IR-spectrum of different complexes, the mechanism underlying the ligand bond formation are discussed. The theoretical frequencies of normal oscillations, satisfactorily described the porphyrin experimental IR-spectrum are received. On the base of both obtained normal oscillation forms and potential energy distribution of vibrational coordinates the detailed theoretical interpretation of the porphyrin molecule vibrational spectrum as well as the analysis of the nature of each absorption band the porphyrin molecule IR-spectrum have been carried out. Porphyrin molecule force field analysis has been showed that the ring electron density is irregular. The results of this study may be used at the theoretical calculations of IR-absorption spectrum of different metallo complexes of the porphyrin

  3. A photosensitizer delivered by bispecific antibody redirected T lymphocytes enhances cytotoxicity against EpCAM-expressing carcinoma cells upon light irradiation.

    Science.gov (United States)

    Blaudszun, André-René; Moldenhauer, Gerhard; Schneider, Marc; Philippi, Anja

    2015-01-10

    Recently conducted clinical trials have provided impressive evidence that chemotherapy resistant metastatic melanoma and several hematological malignancies can be cured using adoptive T cell therapy or T cell-recruiting bispecific antibodies. However, a significant fraction of patients did not benefit from these treatments. Here we have evaluated the feasibility of a novel combination therapy which aims to further enhance the killing potential of bispecific antibody-redirected T lymphocytes by using these cells as targeted delivery system for photosensitizing agents. For a first in vitro proof-of-concept study, ex vivo activated human donor T cells were loaded with a poly(styrene sulfonate) (PSS)-complex of the model photosensitizer 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (mTHPP). In the absence of light and when loading with the water-soluble PSS/mTHPP-complex occurred at a tolerable concentration, viability and cytotoxic function of loaded T lymphocytes were not impaired. When "drug-enhanced" T cells were co-cultivated with EpCAM-expressing human carcinoma cells, mTHPP was transferred to target cells. Notably, in the presence of a bispecific antibody, which cross-links effector and target cells thereby inducing the cytolytic activity of cytotoxic T lymphocytes, significantly more photosensitizer was transferred. Consequently, upon irradiation of co-cultures, redirected drug-loaded T cells were more effective in killing A549 lung and SKOV-3 ovarian carcinoma cells than retargeted unloaded T lymphocytes. Particularly, the additive approach using redirected unloaded T cells in combination with appropriate amounts of separately applied PSS/mTHPP was less efficient as well. Thus, by loading T lymphocytes with a stimulus-sensitive anti-cancer drug, we were able to enhance the cytotoxic capacity of carrier cells. Photosensitizer boosted T cells could open new perspectives for adoptive T cell therapy as well as targeted photodynamic therapy. Copyright © 2014

  4. Progress on research of radioisotope-labeled porphyrin derivatives

    International Nuclear Information System (INIS)

    Yang Yuqing; Pu Manfei; Song Hu; Song Hongtao; Li Xingliang

    2010-01-01

    Porphyrin derivatives can be taken up by tumor cells and accumulated there for a long time. Since 1960's, radioactive isotope-labeled porphyrins have been under extensive researches around the world. The progress of labeled porphyrins with various radioactive isotopes includes 3 H, 11 C, 123 I, 131 I, 99m Tc, 188 Re, 117,113m Sn, 153 Sm, 109 Pd, 111 In, 57 Co, 58 Co, 65 Zn, 64, 67 Cu, 90 Y, 166 Ho is reviewed here. Among them, we studied the labeling conditions, chemical and biochemical properties of 188 Re-labeled, 117,113 mSn-labeled and 153 Sm-labeled T 3,4 CPP and TPPS 4 . We also studied the bio-distribution of 188 Re-labeled T 3,4 CPP and TPPS 4 in mice with transplanted liver tumor and melanoma. Other researches in porphyrins which could affect the research of radioisotope-labeled porphyrins are introduced in the end. This review could provide a reference for design of better radioisotope-labeled porphyrins. (authors)

  5. Impact of iron porphyrin complexes when hydroprocessing algal HTL biocrude

    Energy Technology Data Exchange (ETDEWEB)

    Jarvis, Jacqueline M.; Sudasinghe, Nilusha M.; Albrecht, Karl O.; Schmidt, Andrew J.; Hallen, Richard T.; Anderson, Daniel B.; Billing, Justin M.; Schaub, Tanner M.

    2016-10-01

    We apply Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for direct characterization of iron-porphyrins in hydrothermal liquefaction (HTL) biocrude oils derived from two algae: Tetraselmis sp. and cyanobacteria. The ironporphyrin compounds are shown to cause catalyst bed plugging during hydroprocessing due to iron deposition. Inductively-coupled plasma optical emission spectrometry (ICPOES) was utilized for iron quantitation in the plugged catalyst beds formed through hydroprocessing of the two HTL biocrudes and identifies an enrichment of iron in the upper five centimeters of the catalyst bed for Tetraselmis sp. (Fe=100,728 ppm) and cyanobacteria (Fe=115,450 ppm). Direct infusion FT-ICR MS analysis of the two HTL biocrudes with optimized instrument conditions facilitates rapid screening and identification of iron-porphyrins without prior chromatographic separation. With FT-ICR MS we identify 138 unique iron-porphyrin compounds in the two HTL biocrudes that are structurally similar to metal-porphyrins (e.g. Ni and V) observed in petroleum. No ironporphyrins are observed in the cyanobacteria HTL biocrude after hydroprocessing, which indicates that iron-porphyrin structures in the HTL biocrude are degraded during hydroprocessing. Hydrodemetallization reactions that occur through hydroprocessing of HTL biocrudes could be responsible for the decomposition of iron-porphyrin structures leading to metal deposition in the catalyst bed that result in catalyst deactivation and bed plugging, and must be addressed for effective upgrading of algal HTL biocrudes.

  6. Process for microwave sintering boron carbide

    Science.gov (United States)

    Holcombe, C.E.; Morrow, M.S.

    1993-10-12

    A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

  7. Bright prospects for boron

    NARCIS (Netherlands)

    Nanver, L.; Wassink, J.

    2012-01-01

    Professor Lis Nanver at Dimes has laid the foundation for a range of new photodetectors by creating a thin coating of boron on a silicon substrate. The sensors are used in ASML’s latest lithography machines and FEI’s most sensitive electron microscopes.

  8. Lethal photosensitization of biofilm-grown bacteria

    Science.gov (United States)

    Wilson, Michael

    1997-12-01

    Antibacterial agents are increasingly being used for the prophylaxis and treatment of oral diseases. As these agents can be rendered ineffective by resistance development in the target organisms there is a need to develop alternative antimicrobial approaches. Light-activated antimicrobial agents release singlet oxygen and free radicals which can kill adjacent bacteria and a wide range of cariogenic and periodontopathogenic bacteria has been shown to be susceptible to such agents. In the oral cavity these organisms are present as biofilms (dental plaques) which are less susceptible to traditional antimicrobial agents than bacterial suspensions. The results of these studies have shown that biofilm-grown oral bacteria are also susceptible to lethal photosensitization although the light energy doses required are grater than those needed to kill the organisms when they are grown as aqueous suspensions.

  9. Photosensitizer absorption coefficient modeling and necrosis prediction during Photodynamic Therapy.

    Science.gov (United States)

    Salas-García, Irene; Fanjul-Vélez, Félix; Arce-Diego, José Luis

    2012-09-03

    The development of accurate predictive models for Photodynamic Therapy (PDT) has emerged as a valuable tool to adjust the current therapy dosimetry to get an optimal treatment response, and definitely to establish new personal protocols. Several attempts have been made in this way, although the influence of the photosensitizer depletion on the optical parameters has not been taken into account so far. We present a first approach to predict the spatio-temporal variation of the photosensitizer absorption coefficient during PDT applied to dermatological diseases, taking into account the photobleaching of a topical photosensitizer. This permits us to obtain the photons density absorbed by the photosensitizer molecules as the treatment progresses and to determine necrosis maps to estimate the short term therapeutic effects in the target tissue. The model presented also takes into account an inhomogeneous initial photosensitizer distribution, light propagation in biological media and the evolution of the molecular concentrations of different components involved in the photochemical reactions. The obtained results allow to investigate how the photosensitizer depletion during the photochemical reactions affects light absorption by the photosensitizer molecules as the optical radiation propagates through the target tissue, and estimate the necrotic tumor area progression under different treatment conditions. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Methods of producing continuous boron carbide fibers

    Science.gov (United States)

    Garnier, John E.; Griffith, George W.

    2015-12-01

    Methods of producing continuous boron carbide fibers. The method comprises reacting a continuous carbon fiber material and a boron oxide gas within a temperature range of from approximately 1400.degree. C. to approximately 2200.degree. C. Continuous boron carbide fibers, continuous fibers comprising boron carbide, and articles including at least a boron carbide coating are also disclosed.

  11. Photosensitizer and light diffusion through dentin in photodynamic therapy.

    Science.gov (United States)

    Nogueira, Ana C; Graciano, Ariane X; Nagata, Juliana Y; Fujimaki, Mitsue; Terada, Raquel S S; Bento, Antonio C; Astrath, Nelson G C; Baesso, Mauro L

    2013-05-01

    Photodynamic therapy has been considered a potential antimicrobial modality against oral infections, including dental caries. A model to estimate the penetration of both photosensitizers and light through human dentin, a factor of interest in photodynamic therapy, is proposed. The photoacoustic spectroscopy technique was used to evaluate in vitro dentin permeability of three different photosensitizers. Using the dentin optical absorption and scattering coefficients, it was possible to propose a semi-quantitative model predicting both photosensitizer and light doses within dentin. The graphic illustrations obtained provided guidelines that may be useful in photodynamic therapy protocols used as antimicrobial tools in caries lesions.

  12. Noncovalent functionalization of single-walled carbon nanotubes with porphyrins

    Energy Technology Data Exchange (ETDEWEB)

    Bassiouk, María; Basiuk, Vladimir A. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 México D.F. (Mexico); Basiuk, Elena V., E-mail: elenagd@unam.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 México D.F. (Mexico); Álvarez-Zauco, Edgar [Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510 México D.F. (Mexico); Martínez-Herrera, Melchor [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 México D.F. (Mexico); Rojas-Aguilar, Aaron [Centro de Investigación y de Estudios Avanzados, Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, San Pedro Zacatenco, 07360 México D.F. (Mexico); Puente-Lee, Iván [Facultad de Química, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510 México D.F. (Mexico)

    2013-06-15

    The covalent and noncovalent interactions of porphyrins and related tetraazamacrocyclic compounds with single-walled carbon nanotubes (SWNTs) is a subject of increasing research effort, directed toward the design of novel hybrid nanomaterials combining unique electronic and optical properties of both molecular species. In this report, we used different experimental techniques as well as molecular mechanics (MM) calculations to analyze the adsorption of meso-tetraphenylporphine (or 5,10,15,20-tetraphenyl-21H,23H-porphine, H{sub 2}TPP) and its complexes with Ni(II) and Co(II) (NiTPP and CoTPP, respectively), as well as hemin (a natural porphyrin), onto the surface of SWNTs. Altogether, the results suggested that all four porphyrin species noncovalently interact with SWNTs, forming hybrid nanomaterials. Nevertheless, of all four porphyrin species, the strongest interaction with SWNTs occurs in the case of CoTPP, which is able to intercalate and considerably disperse SWNT bundles, and therefore absorb onto the surface of individual SWNTs. In contrast, NiTPP, CoTPP and hemin, due to a weaker interaction, are unable to do so and therefore are only capable to adsorb onto the surface of SWNT bundles. According to the scanning tunneling microscopy (STM) imaging and MM results, the adsorption of CoTPP onto SWNT sidewalls results in the formation of porphyrin arrays in the shape of long-period interacting helixes with variable periodicity, possibly due to different diameters and chiralities of SWNTs present in the samples. Since the remaining porphyrin species were found to adsorb onto the surface of SWNT bundles, the precise geometry of the corresponding porphyrin/SWNT complexes is difficult to characterize.

  13. Noncovalent functionalization of single-walled carbon nanotubes with porphyrins

    International Nuclear Information System (INIS)

    Bassiouk, María; Basiuk, Vladimir A.; Basiuk, Elena V.; Álvarez-Zauco, Edgar; Martínez-Herrera, Melchor; Rojas-Aguilar, Aaron; Puente-Lee, Iván

    2013-01-01

    The covalent and noncovalent interactions of porphyrins and related tetraazamacrocyclic compounds with single-walled carbon nanotubes (SWNTs) is a subject of increasing research effort, directed toward the design of novel hybrid nanomaterials combining unique electronic and optical properties of both molecular species. In this report, we used different experimental techniques as well as molecular mechanics (MM) calculations to analyze the adsorption of meso-tetraphenylporphine (or 5,10,15,20-tetraphenyl-21H,23H-porphine, H 2 TPP) and its complexes with Ni(II) and Co(II) (NiTPP and CoTPP, respectively), as well as hemin (a natural porphyrin), onto the surface of SWNTs. Altogether, the results suggested that all four porphyrin species noncovalently interact with SWNTs, forming hybrid nanomaterials. Nevertheless, of all four porphyrin species, the strongest interaction with SWNTs occurs in the case of CoTPP, which is able to intercalate and considerably disperse SWNT bundles, and therefore absorb onto the surface of individual SWNTs. In contrast, NiTPP, CoTPP and hemin, due to a weaker interaction, are unable to do so and therefore are only capable to adsorb onto the surface of SWNT bundles. According to the scanning tunneling microscopy (STM) imaging and MM results, the adsorption of CoTPP onto SWNT sidewalls results in the formation of porphyrin arrays in the shape of long-period interacting helixes with variable periodicity, possibly due to different diameters and chiralities of SWNTs present in the samples. Since the remaining porphyrin species were found to adsorb onto the surface of SWNT bundles, the precise geometry of the corresponding porphyrin/SWNT complexes is difficult to characterize.

  14. The coordination chemistry of boron porphyrin complexes B 2 OX 2 ...

    Indian Academy of Sciences (India)

    G I Cárdenas-Jirón1 F Espinoza-Leyton1 T L Sordo2. Laboratorio de Química Teórica, Departamento de Ciencias Químicas, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Correo 33, Santiago, Chile; Departamento de Química Física y Analítica, Universidad de Oviedo, C/Julián Clavería 8, ...

  15. Structures, stability, mechanical and electronic properties of α-boron and α*-boron

    OpenAIRE

    Chaoyu He; J. X. Zhong

    2013-01-01

    The structures, stability, mechanical and electronic properties of α-boron and a promising metastable boron phase (α*-boron) have been studied by first-principles calculations. α-boron and α*-boron consist of equivalent icosahedra B12 clusters in different connecting configurations of “3S-6D-3S” and “2S-6D-4S”, respectively. The total energy calculations show that α*-boron is less stable than α-boron but more favorable than the well-known β-boron and γ-boron at zero pressure. Both α-boron and...

  16. Interaction Studies between Newly Synthesized Photosensitive Polymer and Ionic Liquids

    Directory of Open Access Journals (Sweden)

    In Tae Kim

    2015-01-01

    Full Text Available In this information age, different kinds of photosensitive materials have been used in the manufacture of information storage devices. But these photosensitive materials have the bane of low diffraction efficiency. In order to solve this problem, we have synthesized a novel photosensitive polymer from epoxy-based azopolymers (with three types of azochromophores. Furthermore, we have studied the interaction between this newly synthesized azopolymer and ionic liquids (ILs. For this purpose, we have used the ammonium and imidazolium families of ILs, such as diethylammonium dihydrogen phosphate (DEAP, tributylammonium methyl sulfate (TBMS, triethylammonium 4-aminotoluene-3-sulfonic acid (TASA, and 1-methylimidazolium chloride ([Mim]Cl. To investigate the molecular interaction between azopolymer and ILs, we have used the following spectroscopic methods of analysis: UV-visible spectroscopy, photoluminescence (PL spectroscopy, Fourier transformed infrared spectroscopy (FT-IR, and confocal Raman spectroscopy. In this study, we have developed new photosensitive materials by combining polymer with ILs.

  17. Photoinduced energy and charge transfer in layered porphyrin-gold nanoparticle thin films

    NARCIS (Netherlands)

    Kotiaho, Anne; Lahtinen, Riikka; Lehtivuori, Heli; Tkachenko, Nikolai V.; Lemmetyinen, Helge

    2008-01-01

    In thin films of porphyrin (H2P) and gold nanoparticles (AuNPs), photoexcitation of porphyrins leads to energy and charge transfer to the gold nanoparticles. Alternating layers of porphyrins and octanethiol protected gold nanoparticles (dcore ∼3 nm) were deposited on solid substrates via the

  18. Mitochondria Targeted Protein-Ruthenium Photosensitizer for Efficient Photodynamic Applications

    OpenAIRE

    Chakrabortty, Sabyasachi; Agrawalla, Bikram Keshari; Stumper, Anne; Vegi, Naidu M; Fischer, Stephan; Reichardt, Christian; K?gler, Michael; Dietzek, Benjamin; Feuring-Buske, Michaela; Buske, Christian; Rau, Sven; Weil, Tanja

    2017-01-01

    Organelle-targeted photosensitization represents a promising approach in photodynamic therapy where the design of the active photosensitizer (PS) is very crucial. In this work, we developed a macromolecular PS with multiple copies of mitochondria-targeting groups and ruthenium complexes that displays highest phototoxicity toward several cancerous cell lines. In particular, enhanced anticancer activity was demonstrated in acute myeloid leukemia cell lines, where significant impairment of proli...

  19. Photosensitizing medication use and risk of skin cancer

    DEFF Research Database (Denmark)

    Kaae, Jeanette; Boyd, Heather A; Hansen, Anne

    2010-01-01

    Many commonly used medications, including both medications for long-term (daily) use and short-term use (treatment courses of finite duration), have photosensitizing properties. Whether use of these medications affects skin cancer risk, however, is unclear.......Many commonly used medications, including both medications for long-term (daily) use and short-term use (treatment courses of finite duration), have photosensitizing properties. Whether use of these medications affects skin cancer risk, however, is unclear....

  20. Neutron dosimetry in boron neutron capture therapy

    International Nuclear Information System (INIS)

    Fairchild, R.G.; Miola, U.J.; Ettinger, K.V.

    1981-01-01

    The recent development of various borated compounds and the utilization of one of these (Na 2 B 12 H 11 SH) to treat brain tumors in clinical studies in Japan has renewed interest in neutron capture therapy. In these procedures thermal neutrons interact with 10 B in boron containing cells through the 10 B(n,α) 7 Li reaction producing charged particles with a maximum range of approx. 10μm in tissue. Borated analogs of chlorpromazine, porphyrin, thiouracil and deoxyuridine promise improved tumor uptake and blood clearance. The therapy beam from the Medical Research Reactor in Brookhaven contains neutrons from a modified and filtered fission spectrum and dosimetric consequences of the use of the above mentioned compounds in conjunction with thermal and epithermal fluxes are discussed in the paper. One of the important problems of radiation dosimetry in capture therapy is determination of the flux profile and, hence, the dose profile in the brain. This has been achieved by constructing a brain phantom made of TE plastic. The lyoluminescence technique provides a convenient way of monitoring the neutron flux distributions; the detectors for this purpose utilize 6 Li and 10 B compounds. Such compounds have been synthesized specially for the purpose of dosimetry of thermal and epithermal beams. In addition, standard lyoluminescent phosphors, like glutamine, could be used to determine the collisional component of the dose as well as the contribution of the 14 N(n,p) 14 C reaction. Measurements of thermal flux were compared with calculations and with measurements done with activation foils

  1. Fivefold twinned boron carbide nanowires.

    Science.gov (United States)

    Fu, Xin; Jiang, Jun; Liu, Chao; Yuan, Jun

    2009-09-09

    Chemical composition and crystal structure of fivefold twinned boron carbide nanowires have been determined by electron energy-loss spectroscopy and electron diffraction. The fivefold cyclic twinning relationship is confirmed by systematic axial rotation electron diffraction. Detailed chemical analysis reveals a carbon-rich boron carbide phase. Such boron carbide nanowires are potentially interesting because of their intrinsic hardness and high temperature thermoelectric property. Together with other boron-rich compounds, they may form a set of multiply twinned nanowire systems where the misfit strain could be continuously tuned to influence their mechanical properties.

  2. Persistent photosensitivity after allergic contact dermatitis to epoxy resin.

    Science.gov (United States)

    Kwok, Tiffany; Rosen, Cheryl F; Storrs, Frances J; Lobel, Edmund; DeKoven, Joel G

    2013-01-01

    Persistent photosensitivity after allergic contact dermatitis (ACD) to epoxy resin has rarely been described. The aim of this study was to create awareness that ACD to epoxy may be a trigger for persistent photosensitivity. We present a series of 5 patients who developed ACD to epoxy resin and later a photodistributed eczematous eruption when exposed to sunlight, with a documented decrease in minimal erythema dose to UVA and UVB. The age of patients ranged from 34 to 71 years, and there were 3 men and 2 women. Each patient had occupational exposure to epoxy. Symptoms of epoxy ACD preceded photosensitivity by 5 months to 12 years in 3 cases and occurred simultaneously in 2 cases. Patch testing to epoxy resin was positive in all patients. Phototesting revealed a decreased minimal erythema dose to UVA and UVB in each of the 3 patients who were phototested. Photopatch testing was positive for epoxy resin in 1 of the 2 patients tested. All patients remained photosensitive for at least 2 years after diagnosis, with only 1 case of photosensitivity resolving with extended avoidance of epoxy. There is an association between ACD to epoxy resin and development of persistent photosensitivity. Possible mechanisms to explain the relationship between the 2 phenomena are discussed.

  3. Platinum porphyrins as ionophores in polymeric membrane electrodes

    DEFF Research Database (Denmark)

    Lvova, Larisa; Verrelli, Giorgio; Nardis, Sara

    2011-01-01

    A comparative study of Pt(II)- and Pt(IV)-porphyrins as novel ionophores for anion-selective polymeric membrane electrodes is performed. Polymeric membranes of different compositions, prepared by varying plasticizers, cationic and anionic additives and Pt porphyrins, have been examined by potenti......A comparative study of Pt(II)- and Pt(IV)-porphyrins as novel ionophores for anion-selective polymeric membrane electrodes is performed. Polymeric membranes of different compositions, prepared by varying plasticizers, cationic and anionic additives and Pt porphyrins, have been examined...... within the electrode membranes, while those based on Pt(IV)TPPCl2 operate via a mixed mode carrier mechanism, evidencing also a partial reduction of the starting ionophore to Pt(II)TPP. Spectrophotometric measurements of thin polymeric films indicate that no spontaneous formation of hydroxide ion bridged...... porphyrin dimers occurs in the membrane plasticized both with high or low dielectric constant plasticizer, due to a low oxophilicity of central Pt. The computational study of various anion–Pt(IV)TPPCl2 complex formation by means of semi-empirical and density functional theory (DFT) methods revealed a good...

  4. Supramolecular assemblies of pyridyl porphyrin and diazadithia phthalocyanine

    Directory of Open Access Journals (Sweden)

    OZER BEKAROGLU

    1999-08-01

    Full Text Available In this paper we report for the first time on a mixed complex between the cationic porphyrin 5, 10, 15, 20-tetra-N- -methyl-pyrydinium-p-il porphyrin (TMPyP and a new metal phthalocyanine with four 16-membered diazadithia macrocycles (denoted here as Pc16, in order to obtain an active complex with an intense absorption on the lower energy side of the visible spectrum and with a higher sensitivity in photodynamic therapy of cancer. The dimerization constant for Pc16 and also the ratio between the oscillator strengths for monomeric and dimeric forms of this compound, were evaluated. The ratio between these oscillator strengths was 2.01 showing a certain dimerization process. The Job mathematical method allowed the establishment of the stoichiometry and the formation constants for the heteroaggregates between the porphyrin and the phthalocy- anine (a diad between one phthalocyanine molecule and one porphyrin molecule and a triad between two phthalocyanine molecules and only one porphyrin molecule. The coulombic attraction resulting from the p-p interaction of the two highly conjugated macrocycles and from the interaction between the substituents, favors a face-to-face geometry.

  5. Cobalt-cadmium bimetallic porphyrin coordination polymers for electrochemistry application

    Science.gov (United States)

    Wang, C. Y.; Cui, G. Y.; Ding, D.; Zhou, B.

    2018-01-01

    In this paper, we used tetra (4-carboxyphenyl) porphyrin (H2TCPP) and metal cadmium, cobalt as reactants to synthesize metal porphyrin coordination polymers that they had different metal ratio. They were expressed as Co1Cd3TCPP, Co1Cd1TCPP, Co3Cd1TCPP, respectively. The results were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and inductively coupled plasma atomic emission spectrometer (ICP). Herein, a series of metal porphyrin coordination polymers has multiple metal active centers and constructs electrochemistry sensors. In order to increase the conductivity, multi-walled carbon nanotubes (MWCNTs) can be used to modify the electrodes. The polymer/MWCNTs/GCE electrode was studied by cyclic voltammetry and chronoamperometry as sensor for sodium nitrite. The performance of Co1Cd1TCPP/MWCNTs/GCE electrode is best, the sensitivity for sodium nitrite is 350.95 mA M-1 cm-2 and the. The results indicate that metal porphyrin coordination polymers have excellent performance. It also enriches the application of metal porphyrin coordination polymer in electrochemistry sensor.

  6. Photosensitizers from Spirulina for Solar Cell

    Directory of Open Access Journals (Sweden)

    Liqiu Wang

    2014-01-01

    Full Text Available Spirulina is a kind of blue-green algae with good photosynthetic efficiency and might be used for photovoltaic power generation. So this paper used living spirulina as novel photosensitizer to construct spirulina biosolar cell. The results showed that spirulina had the photoelectric conversion effect, and could let the spirulina biosolar cell have 70 μA photocurrent. Meanwhile, adding glucose sucrose or chitosan in the spirulina anode chamber, they could make the maxima current density of the cell greatly increased by 80 μA, 100 μA, and 84 μA, respectively, and the sucrose could improve the maximum power density of the cell to 63 mW/m−2. Phycobiliprotein played an important role in the photosynthesis of spirulina. So in this paper phycobiliprotein was extracted from spirulina to composite with squaraine dye to sensitize nanocrystalline TiO2 photoanode for building dye sensitized solar cell, and the photoelectric properties of the cell also were investigated.

  7. Primary mechanisms of photosensitization by furocoumarins

    International Nuclear Information System (INIS)

    Grossweiner, L.I.

    1981-01-01

    A proper understanding of the PUVA therapy action mechanism requires the synthesis of concepts developed at the level of molecules, single cells and whole organisms. Although progress has been made in identifying key factors within each level of organization, the interrelationships remain obscure. Important unanswered questions at the molecular and cellular levels include: (1) Which excited states of the furocoumarin in molecule (triplet or excited singlet) are involved in the formation of DNA monoadducts, and the conversion of monoadducts to cross-links. (2) How does the spectrum of the incident radiation affect the distribution of the initial photochemical products from the PUVA sensitizers. (3) What are the relative contributions of furocoumarin-DMA monoadducts, furocoumarin-DNA cross-links and singlet oxygen to mutagenesis and lethality in cells, at the furocoumarin and UV-A dose levels corresponging to PUVA therapy. Additional information about these key aspects of furocoumarin photosensitization should lead to a more definitive relationship of the cellular level events to the endpoints observed with PUVA therapy, and suggest directions for potential improvements in the current clinical procedures

  8. Photosensitizing anthraquinones from Heterophyllaea lycioides (Rubiaceae).

    Science.gov (United States)

    Dimmer, Jesica A; Núñez Montoya, Susana C; Mendoza, Caterine S; Cabrera, José L

    2017-05-01

    Seven anthraquinones were isolated from aerial parts of Heterophyllaea lycioides (Rusby) Sandwith (Rubiaceae), including three derivatives that have not been described before: a hetero-bianthraquinone identified as (R)-2-hydroxymethyl-2'methyl-1,1',6,6'-tetrahydroxy-5,5' bianthraquinone (lycionine), and two mono-chlorinated derivatives related to soranjidiol. One of them is a homo-bianthraquinone: (R)-7-chloro-2,2'-dimethyl-1,1',6,6'-tetrahydroxy-5,5' bianthraquinone (7-chlorobisoranjidiol), whereas the second halogenated derivative corresponds to a monomeric structure: 5-chloro-1,6-dihydroxy-2-methyl anthraquinone (5-chlorosoranjidiol). The four known compounds were already isolated from another species of this genus, H. pustulata, and they were identified as 5,5'-bisoranjidiol, soranjidiol, pustuline and heterophylline. Structural elucidation was performed by means of an extensive spectroscopic analysis, including 1D and 2D NMR data as well as by HRMS analysis. Chemical structures of 7-chlorobisoranjidiol and 5-chlorosoranjidiol were confirmed by their synthesis from 5,5'-bisoranjidiol and soranjidiol, respectively. Type I photosensitizing properties (superoxide anion radical generation, O 2 - ) were assessed by using the nitroblue tetrazolium assay. When lycionine and chlorinated derivatives were irradiated, they enhanced the O 2 - production with respect to the control; 7-chlorobisoranjidiol stood out by generating an increase of 20%, whereas the other anthraquinones only produced a slight increase of 7%. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Autofluorescent Proteins as Photosensitizer in Eukaryontes

    Science.gov (United States)

    Waldeck, Waldemar; Mueller, Gabriele; Wiessler, Manfred; Brom, Manuela; Tóth, Katalin; Braun, Klaus

    2009-01-01

    Since the discovery of the green fluorescent green protein (GFP) in 1961 many variants of fluorescent proteins (FP) were detected. The importance was underlined by the Nobel price award in chemistry 2008 for the invention, application, and development of the GFP by Shimomura, Chalfie and Tsien. GFP, first described by Shimomura now is indispensible in the scientific daily life. Since then and also in future fluorescent proteins will lead to new applications as reporters in cell biology. Such FPs can absorb visible day-light and predominantly one variant of the red fluorescent protein, the KillerRed protein (KRED) emits active electrons producing reactive oxygen species (ROS) leading to photokilling processes in eukaryotes. KRED can be activated by daylight as a photosensitizing agent. It is quite obvious that the KRED's expression and localization is critical with respect to damage, mutation and finally killing of eukaryotic cells. We found evidence that the KRED's cytotoxicity is ascendantly location-dependent from the cell membrane over the nuclear lamina to the chromatin in the cell nucleus. Daylight illumination of cells harbouring the KRED protein fused with the histone H2A, a DNA-binding protein which is critical for the formation of the chromatin structure results in cell killing. Therefore the H2A-KRED fusion protein can be considered as an appropriate candidate for the photodynamic therapy (PDT). This finding can be transferred to current photodynamic approaches and can enhance their therapeutic outcome. PMID:19960122

  10. Studies of porphyrin-containing specimens using an optical spectrometer connected to a confocal scanning laser microscope.

    Science.gov (United States)

    Trepte, O; Rokahr, I; Andersson-Engels, S; Carlsson, K

    1994-12-01

    A spectrometer has been developed for use with a confocal scanning laser microscope. With this unit, spectral information from a single point or a user-defined region within the microscope specimen can be recorded. A glass prism is used to disperse the spectral components of the recorded light over a linear CCD photodiode array with 256 elements. A regulated cooling unit keeps the detector at 277 K, thereby allowing integration times of up to 60 s. The spectral resolving power, lambda/delta lambda, ranges from 350 at lambda = 400 nm to 100 at lambda = 700 nm. Since the entrance aperture of the spectrometer has the same size as the detector pinhole used during normal confocal scanning, the three-dimensional spatial resolution is equivalent to that of normal confocal scanning. Light from the specimen is deflected to the spectrometer by a solenoid controlled mirror, allowing fast and easy switching between normal confocal scanning and spectrometer readings. With this equipment, studies of rodent liver specimens containing porphyrins have been made. The subcellular localization is of interest for the mechanisms of photodynamic therapy (PDT) of malignant tumours. Spectroscopic detection is necessary to distinguish the porphyrin signal from other fluorescent components in the specimen. Two different substances were administered to the tissue, Photofrin, a haematoporphyrin derivative (HPD) and delta-amino levulinic acid (ALA), a precursor to protoporphyrin IX and haem in the haem cycle. Both are substances under clinical trials for PDT of malignant tumours. Following administration of these compounds to the tissue, the potent photosensitizer and fluorescent compound Photofrin, or protoporphyrin IX, respectively, is accumulated.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Chlorophyll a in cyclodextrin supramolecular complexes as a natural photosensitizer for photodynamic therapy (PDT) applications.

    Science.gov (United States)

    Semeraro, Paola; Chimienti, Guglielmina; Altamura, Emiliano; Fini, Paola; Rizzi, Vito; Cosma, Pinalysa

    2018-04-01

    Chlorophyll a (Chl a), an amphipathic porphyrin, was employed as natural photosensitizer for photodynamic therapy applications. Due to its lacking solubility in water and high tendency to aggregate, Chl a was included into different modified cyclodextrins (CDs) to form stable water-soluble supramolecular complexes. To achieve this aim, 2-Hydroxypropyl-β-cyclodextrin (2-HP-β-CD), 2-Hydroxypropyl-γ-cyclodextrin (2-HP-γ-CD), Heptakis(2,6-di-o-methyl)-β-cyclodextrin (DIMEB) and Heptakis(2,3,6-tri-o-methyl)-β-cyclodextrin (TRIMEB) were used. The chemical physical properties of Chl a/CD complexes in cellular medium were studied by means of UV-Vis absorption spectroscopy. Results demonstrated the good aptitude of 2-HP-γ-CD, and more particularly of 2-HP-β-CD, to solubilize the Chl a in cell culture medium in monomeric and photoactive form. Then, Chl a/2-HP-β-CD and Chl a/2-HP-γ-CD complexes were evaluated in vitro on human colorectal adenocarcinoma HT-29 cell line, and cytotoxicity and intracellular localization were respectively assessed. Further tests, such as phototoxicity, ROS generation, intracellular localization and mechanism of cell death were then focused exclusively on Chl a/2-HP-β-CD system. This complex exhibited no dark toxicity and a high phototoxicity toward HT-29 cells inducing cell death via necrotic mechanism. Therefore, it is possible to affirm that Chl a/2-HP-β-CD supramolecular complex could be a promising and potential formulation for applications in photodynamic therapy. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. "Bottom-Up" Construction of Hyperbranched Poly(prodrug-co-photosensitizer) Amphiphiles Unimolecular Micelles for Chemo-Photodynamic Dual Therapy.

    Science.gov (United States)

    Sun, Pei; Wang, Nan; Jin, Xin; Zhu, Xinyuan

    2017-10-25

    Despite the great advantages of chemo-photodynamic combination therapy, tedious synthesis steps and laborious purification procedures make the fabrication of chemo-photodynamic combined therapeutic platforms rather difficult. In this study, we develop a facile "bottom-up" strategy to fabricate hyperbranched poly(prodrug-co-photosensitizer) amphiphiles, h-P(CPTMA-co-BYMAI)-b-POEGMA (hPCBE), for chemo-photodynamic dual therapy. The easily prepared hPCBE possess a bottom-up-constructed hydrophobic core h-P(CPTMA-co-BYMAI) (hPCB) direct copolymerized from reduction-responsive CPT prodrug monomer (CPTMA) and boron dipyrromethene-based photosensitizer monomer (BYMAI), as well as a biocompatible shell polymerized from hydrophilic monomers. Because of the covalently interconnected core-shell structure, hPCBE exists as unimolecular micelles in aqueous solution and exhibits excellent structural stability under dilution condition. The hPCBE micelles can be effectively internalized by MCF-7 cells and release CPT triggered by the reductive milieu. In addition, photosensitizer moieties embedded in the hPCB core could generate singlet oxygen ( 1 O 2 ) effectively under irradiation, endowing hPCBE with the boosting of chemotherapeutic efficacy. As compared to the single chemotherapy of hyperbranched polyprodrug amphiphiles h-PCPTMA-b-POEGMA (hPCE) and photodynamic therapy of hyperbranched polyphotosensitizer amphiphiles h-PBYMAI-b-POEGMA (hPBE), hPCBE shows higher in vitro cytotoxicity. We expect that our approach will further boost research on the design of multifunctional drug delivery systems via the facile "bottom-up" strategy.

  13. Synthesis and properties of photosensitive rubbers. III. Synthesis of chloroacetylated polybutadiene and its photosensitivity

    International Nuclear Information System (INIS)

    Azuma, C.; Hiramatsu, T.; Tanaka, H.; Sanui, K.; Ogata, N.

    1984-01-01

    Polymers having chloroacetate groups were prepared by addition reaction of various chloroacetic acids, such as mono-, di-, and trichloroacetic acids, to cis-1,4-polybutadiene under nitrogen atmosphere for obtaining photosensitive rubbers. The structure of products obtained was identified as a cyclized polybutadiene having pendent chloroacetate groups. The amount of the incorporated substituent increased up to the maximum of around 20 mol %, and the amount of the residual unsaturated groups in the polymer backbone decreased due to the cyclization of the double bond. Chloroacetylated polybutadiene had higher photocrosslinkability by UV irradiation than chloroacetylated chitosan or PVA owing to the high reactivity of the chloroacetate groups and the double bonds in the polymer. The photosensitivity depends both on the amount of the incorporated chloroacetate groups and the residual double bonds in the polymer and also depends on the glass transition temperature (T/sub g/) of the polymer, and the dependence of the crosslinking reaction on T/sub g/ was interpreted to be due to diffusion controlled reaction between excited dichloroacetate groups and olefinic groups in the polymer

  14. Gel-hydrothermal synthesis of carbon and boron co-doped TiO{sub 2} and evaluating its photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yongmei; Xing Mingyang [Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); Zhang Jinlong, E-mail: jlzhang@ecust.edu.cn [Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China)

    2011-08-15

    Graphical abstract: Carbon and boron co-doped TiO{sub 2} photocatalysts were prepared firstly by the gel-hydrothermal method, which presented excellent visible light photocatalytic activities, resulting from the coke carbon photosensitization and B-N synergistic effect. Display Omitted Highlights: {yields} Carbon and boron co-doped TiO{sub 2} photocatalysts with larger surface area were prepared firstly by the gel-hydrothermal method. {yields} Surface coke carbon photosensitization effect is responsible for its high photocatalytic activity in the visible light irradiation. {yields} B-C synergistic effects play the major role in its effective photo-degradation of 2,4-DCP under the visible light. - Abstract: Carbon and boron co-doped TiO{sub 2} photocatalysts were prepared firstly by the gel-hydrothermal method, that is, synthesized through sol-gel process followed by hydrothermal in the glucose solution. The prepared photocatalysts were characterized by XRD, Raman spectra, TEM, N{sub 2} physical adsorption, XPS, and UV-vis absorption spectra. It was found that the co-doped TiO{sub 2} has a larger BET surface areas and a narrower band gap than undoped TiO{sub 2}. The experimental results show that the coke carbon generated on the carbon doped TiO{sub 2} surface act as a photosensitizer and has the photosensitization effect under the visible light. Except for carbon sensitization effect, the boron and carbon co-doped TiO{sub 2} has synergistic effect which is responsible for effective photo-degradation of 2,4-dichlorophenol in the visible light irradiation.

  15. A Novel Photosensitizer 3¹,13¹-phenylhydrazine -Mppa (BPHM) and Its in Vitro Photodynamic Therapy against HeLa Cells.

    Science.gov (United States)

    Li, Wenting; Tan, Guanghui; Cheng, Jianjun; Zhao, Lishuang; Wang, Zhiqiang; Jin, Yingxue

    2016-04-29

    Photodynamic therapy (PDT) has attracted widespread attention due to its potential in the treatment of various cancers. Porphyrinic pyropheophorbide-a (PPa) has been shown to be a potent photosensitizer in PDT experiments. In this paper, a C-3¹,13¹ bisphenylhydrazone modified methyl pyropheophorbide-a (BPHM) was designed and synthesized with the consideration that phenylhydrazone structure may extend absorption wavelength of methyl pyro-pheophorbide-a (Mppa), and make the photosensitizer potential in deep tumor treatment. The synthesis, spectral properties and in vitro photodynamic therapy (PDT) against human HeLa cervical cancer cell line was studied. Methyl thiazolyl tetrazolium (MTT) assay showed the title compound could achieve strong inhibition of cervical cancer cell viability under visible light (675 nm, 25 J/cm²). Cell uptake experiments were performed on HeLa cells. Morphological changes were examined and analyzed by fluorescent inverted microscope. In addition, the mechanism of the photochemical processes of PDT was investigated, which showed that the formation of singlet oxygen after treatment with PDT played a moderate important role.

  16. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    Raman spectroscopic examination was carried out to study the nature of bonding and the allotropic form of boron obtained after electrodeposition. The results obtained from transmission electron microscopy showed the presence of nanocrystallites embedded in an amorphous mass of boron. Raman microscopic studies ...

  17. Effects of Immersion Solvent on Photovoltaic and Photophysical Properties of Porphyrin-Sensitized Solar Cells.

    Science.gov (United States)

    Hayashi, Hironobu; Higashino, Tomohiro; Kinjo, Yuriko; Fujimori, Yamato; Kurotobi, Kei; Chabera, Pavel; Sundström, Villy; Isoda, Seiji; Imahori, Hiroshi

    2015-08-26

    Memory effects in self-assembled monolayers (SAMs) of zinc porphyrin carboxylic acid on TiO2 electrodes have been demonstrated for the first time by evaluating the photovoltaic and electron transfer properties of porphyrin-sensitized solar cells prepared by using different immersion solvents sequentially. The structure of the SAM of the porphyrin on the TiO2 was maintained even after treating the porphyrin monolayer with different neat immersion solvents (memory effect), whereas it was altered by treatment with solutions containing different porphyrins (inverse memory effect). Infrared spectroscopy shows that the porphyrins in the SAM on the TiO2 could be exchanged with the same or analogous porphyrin, leading to a change in the structure of the porphyrin SAM. The memory and inverse memory effects are well correlated with a change in porphyrin geometry, mainly the tilt angle of the porphyrin along the long molecular axis from the surface normal on the TiO2, as well as with kinetics of electron transfer between the porphyrin and TiO2. Such a new structure-function relationship for DSSCs will be very useful for the rational design and optimization of photoelectrochemical and photovoltaic properties of molecular assemblies on semiconductor surfaces.

  18. Antibatic photovoltaic response in zinc-porphyrin-liked oligothiophenes

    DEFF Research Database (Denmark)

    Krebs, Frederik C; Spanggaard, H.

    2005-01-01

    -stannylchloride and subsequent palladium catalysed Stille coupling. We further synthesised 5,15-bis(3, 4', 4", 4"', 4", 4""', 4""", 4"""'-octahexyl-[2, 2'; 5', 2" 5", 2'"; 5"', 2""; 5"", 2""'; 5""', 2"""; 5""", 2"""']octithiophene-5-yl)-10, 20-bis(3, 5-ditertbutylphenyl)zinc(II)porphyrin (5) from trimethyl(3, 4', 4", 4'", 4......"", 4""', 4""", 4"""'-Octahexyl-[2, 2'; 5', 2"; 5"; 2'"; 5"', 2""; 5"", 2"'"; 5""', 2"""; 5""", 2"""']octithiophene-5-yl)stannane (3-SnMe3) and 5, 15-dibromo-10, 20-bis(3, 5-ditertbutylphenyl)zinc(II)porphyrin (6) by Stille coupling. All the products were characterised by size exclusion chromatography...

  19. Synthetic approaches to long-wavelength photosensitizers for photodynamic therapy

    Science.gov (United States)

    Shiau, Fuu-Yau; Pandey, Ravindra K.; Dougherty, Thomas J.; Smith, Kevin M.

    1991-06-01

    Syntheses and chemical characterization of a number of new porphyrin-derived sensitizers related to ''benzoporphyrin derivative'' (BPD) are described. The work discussed centers in solving the isomer problem inherent in BPD synthesis from protoporphyrin IX, with regard to the 2- and 4-vinyls and the 6- and 7-propionic acid groups (Fischer nomenclature).

  20. Hypoxia-targeting antitumor prodrugs and photosensitizers

    International Nuclear Information System (INIS)

    Zhang Zhouen; Nishimoto, S.I.

    2006-01-01

    Tumor hypoxia has been identified as a key subject for tumor therapy, since hypoxic tumor cells show resistance to treatment of tumor tissues by radiotherapy, chemotherapy and phototherapy. For improvement of tumor radiotherapy, we have proposed a series of radiation-activated prodrugs that could selectively release antitumor agent 5-fluorouracil or 5-fluorodeoxyuridine under hypoxic conditions. Recently, we attempted to develop two families of novel hypoxia-targeting antitumor agents, considering that tumor-hypoxic environment is favorable to biological and photochemical reductions. The first family of prodrugs was derived from camptothecin as a potent topoisomerase I inhibitor and several bioreductive motifs. These prodrugs could be activated by NADPH-cytochrome P450 reductase or DT-diaphorase to release free camptothecin, and thereby showed hypoxia-selective cytotoxictiy towards tumor cells. These prodrugs were also applicable to the real-time monitoring of activation and antitumor effect by fluorometry. Furthermore, the camptothecin-bioreductive motif conjugates was confirmed to show an oxygen-independent DAN photocleaving activity, which could overcome a drawback of back electron transfer occurring in the photosensitized one-electron oxidation of DNA. Thus, these camptothecin derivatives could be useful to both chemotherapy and phototherapy for hypoxic tumor cells. The second family of prodrugs harnessed UV light for cancer therapy, incorporating the antitumor agent 5-fluorourcil and the photolabile 2-nitrobenzyl chromophores. The attachment of a tumor-homing cyclic peptide CNGRC was also employed to construct the prototype of tumor-targeting photoactiaved antitumor prodrug. These novel prodrugs released high yield of 5-fluorourcil upon UV irradiation at λ ex =365 nm, while being quite stable in the dark. The photoactivation mechanism was also clarified by means of nanosecond laser flash photolysis. (authors)

  1. Functionalized boron nitride nanotubes

    Science.gov (United States)

    Sainsbury, Toby; Ikuno, Takashi; Zettl, Alexander K

    2014-04-22

    A plasma treatment has been used to modify the surface of BNNTs. In one example, the surface of the BNNT has been modified using ammonia plasma to include amine functional groups. Amine functionalization allows BNNTs to be soluble in chloroform, which had not been possible previously. Further functionalization of amine-functionalized BNNTs with thiol-terminated organic molecules has also been demonstrated. Gold nanoparticles have been self-assembled at the surface of both amine- and thiol-functionalized boron nitride Nanotubes (BNNTs) in solution. This approach constitutes a basis for the preparation of highly functionalized BNNTs and for their utilization as nanoscale templates for assembly and integration with other nanoscale materials.

  2. Boron Activated Neutron Thermometer

    Energy Technology Data Exchange (ETDEWEB)

    Lapsley, A. C. [Argonne National Lab. (ANL), Argonne, IL (United States). Instrument Research & Development

    1952-01-09

    The Brown Instrument Division of Minneapolis-Honeywell Regulator Co. have been making pilot models of boron coated neutron sensitive thermopiles, which show considerable promise of being effective indicators of slow neutron flux. Their loss in sensitivity in a year of operation in the maximum flux of CP-6 calculates to be less than 6 per cent. When used as rooftop indicators, the ratio of the signal of the two units would change by about 2 per cent in a year's time.

  3. Boron atom reactions

    International Nuclear Information System (INIS)

    Estes, R.; Tabacco, M.B.; Digiuseppe, T.G.; Davidovits, P.

    1982-01-01

    The reaction rates of atomic boron with various epoxides have been measured in a flow tube apparatus. The bimolecular rate constants, in units of cm 3 molecule -1 s -1 , are: 1,2-epoxypropane (8.6 x 10 -11 ), 1,2-epoxybutane (8.8 x 10 -11 ), 1,2,3,4-diepoxybutane (5.5 x 10 -11 ), 1-chloro-2,3-epoxypropane (5.7 x 10 -11 ), and 1,2-epoxy-3,3,3-trichloropropane (1.5 x 10 -11 ). (orig.)

  4. Liposomal photosensitizers: potential platforms for anticancer photodynamic therapy

    Directory of Open Access Journals (Sweden)

    L.A. Muehlmann

    2011-08-01

    Full Text Available Photodynamic therapy is a well-established and clinically approved treatment for several types of cancer. Antineoplastic photodynamic therapy is based on photosensitizers, i.e., drugs that absorb photons translating light energy into a chemical potential that damages tumor tissues. Despite the encouraging clinical results with the approved photosensitizers available today, the prolonged skin phototoxicity, poor selectivity for diseased tissues, hydrophobic nature, and extended retention in the host organism shown by these drugs have stimulated researchers to develop new formulations for photodynamic therapy. In this context, due to their amphiphilic characteristic (compatibility with both hydrophobic and hydrophilic substances, liposomes have proven to be suitable carriers for photosensitizers, improving the photophysical properties of the photosensitizers. Moreover, as nanostructured drug delivery systems, liposomes improve the efficiency and safety of antineoplastic photodynamic therapy, mainly by the classical phenomenon of extended permeation and retention. Therefore, the association of photosensitizers with liposomes has been extensively studied. In this review, both current knowledge and future perspectives on liposomal carriers for antineoplastic photodynamic therapy are critically discussed.

  5. Investigation of defects in highly photosensitive germanosilicate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Simmons-Potter, K.; Potter, B.G. Jr.; Warren, W.L.

    1997-02-01

    Germanosilicate glasses exhibit a significant photosensitive response which has been linked to the presence of oxygen-deficient germanium point defects in the glass structure. Based on this correlation, highly photosensitive thin films have been engineered which demonstrate the largest reported ultraviolet-induced refractive index perturbations (An) in an as-synthesized material. Our thin-film fabrication process avoids the use of hydrogen sensitizing treatments and, thus, yields stable films which retain their predisposition for large photosensitivity for over one year of storage. Understanding the nature of the defects in such films and their relationship to charge trapping and enhanced photosensitivity is of paramount importance in designing and optimizing the materials. Toward this end, our films have been studied using electron paramagnetic resonance (EPR), capacitance-voltage, and optical bleaching and absorption spectroscopies. We find experimental evidence suggesting a model in which a change in spin state and charge state of isolated paramagnetic neutral Ge dangling bonds form either diamagnetic positively or negatively charged Ge sites which are largely responsible for the charge trapping and photosensitivity in these thin films. We present experimental data and theoretical modeling to support our defect model and to show the relevance of the work.

  6. Vitamin Bc -Bearing Hydrophilic Photosensitizer Conjugate for Photodynamic Cancer Theranostics.

    Science.gov (United States)

    Kim, Jiyoung; Kim, Kyoung Sub; Park, Sin-jung; Na, Kun

    2015-08-01

    The accurate diagnosis and proper therapy for cancer are essential to improve the success rate of cancer treatment. Here, we demonstrated that the vitamin Bc -bearing hydrophilic photosensitizer conjugate folic acid-polyethylene glycol-pheophorbideA (FA-PEG-PheoA) has been synthesized for the intracellular diagnosis and photodynamic therapy of a tumor. The synthesized vitamin Bc -bearing hydrophilic photosensitizer conjugate has been characterized for the folic acid receptor expressing the ability to target tumor cells, which is facilitated by the chemical conjugation with folic acid. The vitamin Bc -bearing hydrophilic photosensitizer conjugate internalization mechanism was identified through a competitive inhibition test with free folic acid. We optimized the laser-sensitive, cytotoxicity changeable, vitamin Bc -bearing hydrophilic photosensitizer conjugate concentration, which is non-cytotoxic under normal conditions and specifically cytotoxic toward cancer cells (maximum 69.15%) under laser irradiation conditions used for theranostic agents. The cancer therapeutic and diagnosis effects of synthesized conjugate were confirmed in MDA-MB-231 cells and MDA-MB-231-bearing mice. As a result, the vitamin Bc -bearing hydrophilic photosensitizer conjugate exhibited a highly photodynamic therapeutic effect, which enabled the selective detection of a folic acid receptor expressing cancer using optical imaging. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Multifunctional photosensitizer-based contrast agents for photoacoustic imaging.

    Science.gov (United States)

    Ho, Chris Jun Hui; Balasundaram, Ghayathri; Driessen, Wouter; McLaren, Ross; Wong, Chi Lok; Dinish, U S; Attia, Amalina Binte Ebrahim; Ntziachristos, Vasilis; Olivo, Malini

    2014-06-18

    Photoacoustic imaging is a novel hybrid imaging modality combining the high spatial resolution of optical imaging with the high penetration depth of ultrasound imaging. Here, for the first time, we evaluate the efficacy of various photosensitizers that are widely used as photodynamic therapeutic (PDT) agents as photoacoustic contrast agents. Photoacoustic imaging of photosensitizers exhibits advantages over fluorescence imaging, which is prone to photobleaching and autofluorescence interference. In this work, we examined the photoacoustic activity of 5 photosensitizers: zinc phthalocyanine, protoporphyrin IX, 2,4-bis [4-(N,N-dibenzylamino)-2,6-dihydroxyphenyl] squaraine, chlorin e6 and methylene blue in phantoms, among which zinc phthalocyanine showed the highest photoacoustic activity. Subsequently, we evaluated its tumor localization efficiency and biodistribution at multiple time points in a murine model using photoacoustic imaging. We observed that the probe localized at the tumor within 10 minutes post injection, reaching peak accumulation around 1 hour and was cleared within 24 hours, thus, demonstrating the potential of photosensitizers as photoacoustic imaging contrast agents in vivo. This means that the known advantages of photosensitizers such as preferential tumor uptake and PDT efficacy can be combined with photoacoustic imaging capabilities to achieve longitudinal monitoring of cancer progression and therapy in vivo.

  8. Multifunctional Photosensitizer-Based Contrast Agents for Photoacoustic Imaging

    Science.gov (United States)

    Ho, Chris Jun Hui; Balasundaram, Ghayathri; Driessen, Wouter; McLaren, Ross; Wong, Chi Lok; Dinish, U. S.; Attia, Amalina Binte Ebrahim; Ntziachristos, Vasilis; Olivo, Malini

    2014-06-01

    Photoacoustic imaging is a novel hybrid imaging modality combining the high spatial resolution of optical imaging with the high penetration depth of ultrasound imaging. Here, for the first time, we evaluate the efficacy of various photosensitizers that are widely used as photodynamic therapeutic (PDT) agents as photoacoustic contrast agents. Photoacoustic imaging of photosensitizers exhibits advantages over fluorescence imaging, which is prone to photobleaching and autofluorescence interference. In this work, we examined the photoacoustic activity of 5 photosensitizers: zinc phthalocyanine, protoporphyrin IX, 2,4-bis [4-(N,N-dibenzylamino)-2,6-dihydroxyphenyl] squaraine, chlorin e6 and methylene blue in phantoms, among which zinc phthalocyanine showed the highest photoacoustic activity. Subsequently, we evaluated its tumor localization efficiency and biodistribution at multiple time points in a murine model using photoacoustic imaging. We observed that the probe localized at the tumor within 10 minutes post injection, reaching peak accumulation around 1 hour and was cleared within 24 hours, thus, demonstrating the potential of photosensitizers as photoacoustic imaging contrast agents in vivo. This means that the known advantages of photosensitizers such as preferential tumor uptake and PDT efficacy can be combined with photoacoustic imaging capabilities to achieve longitudinal monitoring of cancer progression and therapy in vivo.

  9. Studies on Preparation of Photosensitizer Loaded Magnetic Silica Nanoparticles and Their Anti-Tumor Effects for Targeting Photodynamic Therapy

    Directory of Open Access Journals (Sweden)

    Chen Zhi-Long

    2009-01-01

    Full Text Available Abstract As a fast developing alternative of traditional therapeutics, photodynamic therapy (PDT is an effective, noninvasive, nontoxic therapeutics for cancer, senile macular degeneration, and so on. But the efficacy of PDT was compromised by insufficient selectivity and low solubility. In this study, novel multifunctional silica-based magnetic nanoparticles (SMNPs were strategically designed and prepared as targeting drug delivery system to achieve higher specificity and better solubility. 2,7,12,18-Tetramethyl-3,8-di-(1-propoxyethyl-13,17-bis-(3-hydroxypropyl porphyrin, shorted as PHPP, was used as photosensitizer, which was first synthesized by our lab with good PDT effects. Magnetite nanoparticles (Fe3O4 and PHPP were incorporated into silica nanoparticles by microemulsion and sol–gel methods. The prepared nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and fluorescence spectroscopy. The nanoparticles were approximately spherical with 20–30 nm diameter. Intense fluorescence of PHPP was monitored in the cytoplasm of SW480 cells. The nanoparticles possessed good biocompatibility and could generate singlet oxygen to cause remarkable photodynamic anti-tumor effects. These suggested that PHPP-SMNPs had great potential as effective drug delivery system in targeting photodynamic therapy, diagnostic magnetic resonance imaging and magnetic hyperthermia therapy.

  10. Photosensitization of InP/ZnS quantum dots for anti-cancer and anti-microbial applications

    Science.gov (United States)

    Nadeau, Jay; Chibli, Hicham; Carlini, Lina

    2012-03-01

    Cadmium-free quantum dots (QDs), such as those made from InP, show similar optical properties to those containing toxic heavy metals and thus provide a promising alternative for imaging and therapeutics. The band gap of InP is similar to that of CdTe, so photosensitization of InP QDs with porphyrins or other dyes should lead to generation of reactive oxygen species, useful for targeted destruction of malignant cells or pathogenic bacteria. Here we show the results of measurements of singlet oxygen and superoxide generation from InP QDs with single and double ZnS shells compared with CdTe and CdSe/ZnS. Reactive oxygen species are measured using colorimetric or fluorescent reporter assays and spin-trap electron paramagnetic resonance (EPR) spectroscopy. We find that the size of the InP QDs and the thickness of the ZnS shell both strongly influence ROS generation. These results suggest future approaches to the design of therapeutic nanoparticles.

  11. Trilobolide-porphyrin conjugates: On synthesis and biological effects evaluation

    Czech Academy of Sciences Publication Activity Database

    Tomanová, P.; Rimpelová, S.; Jurášek, M.; Buděšínský, Miloš; Vejvodová, L.; Ruml, T.; Kmoníčková, E.; Drašar, P. B.

    2015-01-01

    Roč. 97, SI (2015), s. 8-12 ISSN 0039-128X Grant - others:GA ČR(CZ) GA14-04329S; GA MŠk(CZ) ED2.1.00/03.0076 Institutional support: RVO:61388963 Keywords : trilobolide * porphyrin * nitric oxide * fluorescence microscopy Subject RIV: CE - Biochemistry Impact factor: 2.513, year: 2015

  12. Expanded porphyrins as third order non-linear optical materials ...

    Indian Academy of Sciences (India)

    WINTEC

    function correlations ... An understanding of the structure–function corre- lations of these expanded porphyrins is an important first step for ... where χ (2) and χ (3) are the quadratic χ (2) (first- order) and χ (3) cubic (second-order) susceptibilities.

  13. Preparation and characterization of free-standing pure porphyrin ...

    Indian Academy of Sciences (India)

    The innovation of this modified `reprecipitation method' lies on the judicial selection of organic solvent and amount of porphyrin solution to be injected in the aqueous media. Exactly similar ... pure nanoparticles. This improved method will lead to produce organic nanoparticles of -conjugated systems easily and efficiently.

  14. 21 CFR 862.1595 - Porphyrins test system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Porphyrins test system. 862.1595 Section 862.1595 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... metabolism), and other diseases characterized by alterations in the heme pathway. (b) Classification. Class I...

  15. Re(I) bridged porphyrin dyads, triads and tetrads

    Indian Academy of Sciences (India)

    DNA cleavage.4 Design strategies to develop solid-state multichromophore arrays of defined rigidity, ... lent synthetic strategies to porphyrin arrays have gen- erally proved quite limiting. The covalent synthetic ...... since retention times vary inversely with size.23 Pulsed- field-gradient NMR, which measures coefficients for.

  16. First observation of an iron porphyrin in heavy crude oil

    International Nuclear Information System (INIS)

    Franceskin, P.J.; Gonzalez-Jimenez, F.; La Rosa, M.G.; Abrams, O.; Katan, L.

    1986-01-01

    Studying one of the iron rich crudes from Orinoco river region using Moessbauer effect, an iron porphyrin was clearly identified for the first time in a heavy oil; its structure is DPEP type and the iron state is divalent (FeII) with low spin. (Auth.)

  17. SYNTHESIS AND PROPERTIES OF STERICALLY HINDERED WATER SOLUBLE PORPHYRINE

    Directory of Open Access Journals (Sweden)

    Yu. V. Ishkov

    2014-12-01

    Full Text Available 5,10,15,20-(2-methoxy-3-quinolinylporphyrine, which was a mixture of atropisomers, was obtained by condensation of 2-methoxyquinoline-3-carbaldehyde with pyrrole in propionic acid. Quaternization of nitrogen atoms of peripheric substituents in this compound lead to water soluble sterically hindered porphyrine.

  18. Modulation of Group I Ribozyme Activity by Cationic Porphyrins

    Directory of Open Access Journals (Sweden)

    Shigeyoshi Matsumura

    2015-03-01

    Full Text Available The effects of cationic porphyrins on the catalytic activities of four group I ribozymes were investigated. A cationic porphyrin possessing four pyridinium moieties (pPyP inhibited two group IC3 ribozymes (Syn Rz and Azo Rz and a group IC1 ribozyme (Tet Rz. In the case of a group IA2 ribozyme (Td Rz, however, pPyP served not only as an inhibitor but also as an activator, and the effects of pPyP were dependent on its concentration. To analyze the structural and electronic factors determining the effects of pPyP on group I ribozymes, three cationic porphyrins (pPyNCP, pPyF4P, and TMPyP were also examined. As interactions between small organic molecules and nucleic acids are attractive and important issues in biochemistry and biotechnology, this study contributes to the development of porphyrin-based molecules that can modulate functions of structured RNA molecules.

  19. Synthesis and photophysical study of unsymmetrical porphyrin arrays

    Indian Academy of Sciences (India)

    Administrator

    Porphyrin-based dimers, trimers and oligomers have received considerable attention as models for the study of electron transfer and energy transfer processes in photosynthesis. Multiporphyrin arrays are also attractive because of their potential use in nonlinear optics, molecular devices and photodynamic therapy of ...

  20. Electronic interaction between nitrogen-doped graphene and porphyrin molecules.

    Science.gov (United States)

    Pham, Van Dong; Lagoute, Jérôme; Mouhoub, Ouafi; Joucken, Frédéric; Repain, Vincent; Chacon, Cyril; Bellec, Amandine; Girard, Yann; Rousset, Sylvie

    2014-09-23

    The chemical doping of graphene is a promising route to improve the performances of graphene-based devices through enhanced chemical reactivity, catalytic activity, or transport characteristics. Understanding the interaction of molecules with doped graphene at the atomic scale is therefore a leading challenge to be overcome for the development of graphene-based electronics and sensors. Here, we use scanning tunneling microscopy and spectroscopy to study the electronic interaction of pristine and nitrogen-doped graphene with self-assembled tetraphenylporphyrin molecules. We provide an extensive measurement of the electronic structure of single porphyrins on Au(111), thus revealing an electronic decoupling effect of the porphyrins adsorbed on graphene. A tip-induced switching of the inner hydrogen atoms of porphyrins, first identified on Au(111), is observed on graphene, allowing the identification of the molecular conformation of porphyrins in the self-assembled molecular layer. On nitrogen-doped graphene, a local modification of the charge transfer around the nitrogen sites is evidenced via a downshift of the energies of the molecular elecronic states. These data show how the presence of nitrogen atoms in the graphene network modifies the electronic interaction of organic molecules with graphene. These results provide a basic understanding for the exploitation of doped graphene in molecular sensors or nanoelectronics.

  1. The effects of urea, guanidinium chloride and sorbitol on porphyrin ...

    Indian Academy of Sciences (India)

    parallel computers including 40 processor units. The computer applied the Rocks cluster networking and. Centos operating systems. Results were calculated by three repeated and averaged trajectory of simulation. 2.2 Data analyses. The conformational changes of the porphyrin during. MD simulations were monitored by ...

  2. Porphyrin involvement in redshift fluorescence in dentin decay

    Science.gov (United States)

    Slimani, A.; Panayotov, I.; Levallois, B.; Cloitre, T.; Gergely, C.; Bec, N.; Larroque, C.; Tassery, H.; Cuisinier, F.

    2014-05-01

    The aim of this study was to evaluate the porphyrin involvement in the red fluorescence observed in dental caries with Soprolife® light-induced fluorescence camera in treatments mode (SOPRO, ACTEON Group, La Ciotat, France) and Vistacam® camera (DÜRR DENTAL AG, Bietigheim-Bissingen, Germany). The International Caries Detection and Assessment System (ICDAS) was used to rand the samples. Human teeth cross-sections, ranked from ICDAS score 0 to 6, were examined by epi-fluorescence microscopy and Confocal Raman microscopy. Comparable studies were done with Protoporphyrin IX, Porphyrin I and Pentosidine solutions. An RGB analysis of Soprolife® images was performed using ImageJ Software (1.46r, National Institutes of Health, USA). Fluorescence spectroscopy and MicroRaman spectroscopy revealed the presence of Protoporphyrin IX, in carious enamel, dentin and dental plaque. However, the presence of porphyrin I and pentosidine cannot be excluded. The results indicated that not only porphyrin were implicated in the red fluorescence, Advanced Glygation Endproducts (AGEs) of the Maillard reaction also contributed to this phenomenon.

  3. Re(I) bridged porphyrin dyads, triads and tetrads

    Indian Academy of Sciences (India)

    Porphyrin rings containing two meso-pyridyl groups either in cis or trans fashion can be used to construct Re(I) ... phyrin squares have been used for catalysis, chemical sensing, molecular sieving and photocurrent production studies. An overview of ... graphic purification resulting in a low product yield. Non-covalent ...

  4. Resonance Raman study on distorted symmetry of porphyrin in ...

    Indian Academy of Sciences (India)

    influence many chemical and photochemical properties of porphyrins in biological reactions; the non-planar conformations have been proposed to play a major role in reactions catalysed by vitamin B12 [35] in the formation of co-factor of F430 in methyl reductase of tetrapyrrole pigments of photosynthetic reaction centers ...

  5. Photosensitive materials and potential of photocurrent mediated tissue regeneration.

    Science.gov (United States)

    Jin, Guorui; Prabhakaran, Molamma P; Liao, Susan; Ramakrishna, Seeram

    2011-02-07

    Photocurrent therapy with participation of light and electrical stimulations could be an innovative and promising approach in regenerative medicine, especially for skin and nerve regeneration. Photocurrent is generated when light irradiates on a photosensitive device, and with more and more types of photosensitive materials being synthesized, photocurrent could be applied for enhanced regeneration of tissue. Photosensitive scaffolds such as composite poly (3-hexylthiophene)/polycaprolactone (P3HT/PCL) nanofibers are fabricated by electrospinning process in our lab for skin regeneration in presence of applied photocurrent. This review article discuss on the various in vitro, in vivo and clinical studies that utilized the principle of 'electrotherapy' and 'phototherapy' for regenerative medicine and evaluates the potential application of photocurrent in regenerative medicine. We conclude that photocurrent therapy will play an important role in regenerative medicine. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. 77 FR 9678 - Prospective Grant of Exclusive License: Photosensitizing Antibody-Fluorophore Conjugates for...

    Science.gov (United States)

    2012-02-17

    ... photoimmunotherapy (PIT). The therapeutic agent is a targeted photosensitizer composed of a tumor specific antibody... photosensitizer. The prospective exclusive evaluation option license will comply with the terms and conditions of...

  7. Boron isotopes and groundwater pollution

    International Nuclear Information System (INIS)

    Vengosh, A.

    1999-01-01

    Boron can be used as a tracer in ground water because of its high solubility in aqueous solutions, natural abundance in all waters, and the lack of effects by evaporation, volatilisation, oxidation-reduction reactions. Since the boron concentrations in pristine ground waters are generally low and contaminant sources are usually enriched in boron, the δ 11 B of groundwater is highly sensitive to the impact of contamination. The large isotopic variations of the potential sources can be used to trace the origin of the contamination and to reconstruct mixing and flow paths

  8. Lattice dynamics of α boron and of boron carbide

    International Nuclear Information System (INIS)

    Vast, N.

    1999-01-01

    The atomic structure and the lattice dynamics of α boron and of B 4 C boron carbide have been studied by Density Functional Theory (D.F.T.) and Density Functional Perturbation Theory (D.F.P.T.). The bulk moduli of the unit-cell and of the icosahedron have been investigated, and the equation of state at zero temperature has been determined. In α boron, Raman diffusion and infrared absorption have been studied under pressure, and the theoretical and experimental Grueneisen coefficients have been compared. In boron carbide, inspection of the theoretical and experimental vibrational spectra has led to the determination of the atomic structure of B 4 C. Finally, the effects of isotopic disorder have been modeled by an exact method beyond the mean-field approximation, and the effects onto the Raman lines has been investigated. The method has been applied to isotopic alloys of diamond and germanium. (author)

  9. Laser inactivation of periodontal bacteria using photosensitizing dyes

    Science.gov (United States)

    Golding, Paul S.; Maddocks, L.; King, Terence A.; Drucker, D. B.

    1996-12-01

    We demonstrate the killing of the oral bacteria Prevotella nigrescens using a photosensitizer and light from a 10 Hz, frequency doubled, Q-switched Nd:YAG pumped dye laser, with modified oscillator to increase output power. This system produced light at wavelengths close to 620 nm, the absorption maximum of the photosensitizing agent, malachite green isothiocyanate, a wavelength that is not significantly absorbed by tissue. A bacterial reduction of 97.5 percent was achieved at an energy density of 0.67 J/cm2 and exposure times of 300 seconds.

  10. Virucidal Nanofiber Textiles Based on Photosensitized Production of Singlet Oxygen

    Science.gov (United States)

    Lhotáková, Yveta; Plíštil, Lukáš; Morávková, Alena; Kubát, Pavel; Lang, Kamil; Forstová, Jitka; Mosinger, Jiří

    2012-01-01

    Novel biomaterials based on hydrophilic polycaprolactone and polyurethane (Tecophilic®) nanofibers with an encapsulated 5,10,5,20-tetraphenylporphyrin photosensitizer were prepared by electrospinning. The doped nanofiber textiles efficiently photo-generate O2(1Δg), which oxidize external chemical and biological substrates/targets. Strong photo-virucidal effects toward non-enveloped polyomaviruses and enveloped baculoviruses were observed on the surface of these textiles. The photo-virucidal effect was confirmed by a decrease in virus infectivity. In contrast, no virucidal effect was detected in the absence of light and/or the encapsulated photosensitizer. PMID:23139839

  11. High-Efficiency Iron Photosensitizer Explained with Quantum Wavepacket Dynamics

    DEFF Research Database (Denmark)

    Pápai, Mátyás Imre; Vankó, György; Rozgonyi, Tamas

    2016-01-01

    Fe(II) complexes have long been assumed unsuitable as photosensitizers because of their low-lying nonemissive metal centered (MC) states, which inhibit electron transfer. Herein, we describe the excited-state relaxation of a novel Fe(II) complex that incorporates N-heterocyclic carbene ligands...... with the conversion into the 3MC states. The slowest component of the 3MLCT decay, important in the context of photosensitizers, is much longer than related Fe(II) complexes because the population transfer to the 3MC states occurs in a region of the potential where the energy gap between the 3MLCT and 3MC states...

  12. Bionic catalysis of porphyrin for electrochemical detection of nucleic acids

    International Nuclear Information System (INIS)

    Li Jie; Lei Jianping; Wang Quanbo; Wang Peng; Ju Huangxian

    2012-01-01

    Highlights: ► This is the first application of bionic catalysis of porphyrin as detection probe in bioanalysis. ► Porphyrin–DNA–gold nanoparticle probe is synthesized. ► Binding model between FeTMPyP and DNA is verified. ► The detection probe shows excellent electrocatalytic behaviors toward the reduction of O 2 . ► The biosensor exhibited good performance with wide linear range and high specificity. - Abstract: A novel electrochemical strategy was designed for the detection of DNA based on the bionic catalysis of porphyrin. The detection probe was prepared via the assembly of thiolated double strand DNA (dsDNA) with gold nanoparticles (AuNPs), and then interacted with cationic iron (III) meso-tetrakis (N-methylphyridinum-4-yl) porphyrin (FeTMPyP) via groove binding along the dsDNA surface. The resulting nanocomplex was characterized with transmission electron microscopy, UV–vis absorption and circular dichroism spectroscopy. The FeTMPyP–DNA–AuNPs probe on gold electrode demonstrated the excellent electrocatalytic behaviors toward the reduction of O 2 due to the largely loading of FeTMPyP and good conductivity. Based on bionic catalysis of porphyrin for the reduction of O 2 , the resulting biosensor exhibited a good performance for the detection of DNA with a wide linear range from 1 × 10 −12 to 1 × 10 −8 mol L −1 and detection limit of 2.5 × 10 −13 mol L −1 at the signal/noise of 3. More importantly, the biosensor presented excellent ability to discriminate the perfectly complementary target and the mismatched stand. This strategy could be conveniently extended for detection of other biomolecules. To the best of our knowledge, this is the first application of bionic catalysis of porphyrin as detection probe and opens new opportunities for sensitive detection of biorecognition events.

  13. A new and effective approach to boron removal by using novel boron-specific fungi isolated from boron mining wastewater.

    Science.gov (United States)

    Taştan, Burcu Ertit; Çakir, Dilara Nur; Dönmez, Gönül

    2016-01-01

    Boron-resistant fungi were isolated from the wastewater of a boron mine in Turkey. Boron removal efficiencies of Penicillium crustosum and Rhodotorula mucilaginosa were detected in different media compositions. Minimal Salt Medium (MSM) and two different waste media containing molasses (WM-1) or whey + molasses (WM-2) were tested to make this process cost effective when scaled up. Both isolates achieved high boron removal yields at the highest boron concentrations tested in MSM and WM-1. The maximum boron removal yield by P. crustosum was 45.68% at 33.95 mg l(-1) initial boron concentration in MSM, and was 38.97% at 42.76 mg l(-1) boron for R. mucilaginosa, which seemed to offer an economically feasible method of removing boron from the effluents.

  14. Evaluation of carboranylporphyrins as boron delivery agents for neutron capture therapy

    International Nuclear Information System (INIS)

    Kawabata, Shinji; Barth, Rolf F.; Yang, Weilian; Wu, Gong; Binns, Peter J.; Riley, Kent J.; Ongayi, Owendi; Gottumukkala, Vijay; Vicente, Graca H.

    2006-01-01

    The goals of the present study were two-fold. First, to determine the biodistribution of three carboranyl-porphyrins, designated H 2 DCP, H 2 TCP and H 2 TBP following intracerebral (i.c.) administration by means of convection enhanced delivery (CED) to F98 glioma bearing rats. Tumor boron concentrations immediately after CED were 36 and 88 μg/g for H 2 DCP and H 2 TCP, respectively, and were 103 and 62 μg/g for H 2 TCP and H 2 TBP, respectively, 24h after termination of CED. The corresponding normal brain concentrations were 5.2, 3.3 and 0.8 μg/g, and blood and liver concentrations all were 2 TCP and H 2 TBP as boron delivery agents in F98 glioma bearing rats. BNCT was carried out at the Massachusetts Institute of Technology (MIT) Research Reactor (MITRR) 24 h after CED of 200 μl of either 0.5 mg of H 2 TCP or H 2 TBP. Untreated control rats all died within 29 days after tumor implantation and had a mean survival time (MST) of 23±3 days and irradiated controls had a MST of 27±3 days. Animals that received H 2 TCP by CED, followed by BNCT, had a MST of 35±4 days and animals received H 2 TBP had a MST of 44±10 days. Further studies were carried out using H 2 TBP at a dose of 0.2 mg administered by a Harvard pump, either alone or in combination with i.v. BPA, and the corresponding MSTs were 34±3 d and 43±9 d, respectively. Histopathologic examination of the brains of animals that died revealed large numbers of porphyrin laden macrophages and extracellular accumulations of free porphyrin indicating that tumor cell uptake was suboptimal. Further studies are planned to synthesize and evaluate new compounds that will have enhanced cellular uptake and efficacy as boron delivery agents for NCT. (author)

  15. Nothing Boring About Boron

    Science.gov (United States)

    Pizzorno, Lara

    2015-01-01

    The trace mineral boron is a micronutrient with diverse and vitally important roles in metabolism that render it necessary for plant, animal, and human health, and as recent research suggests, possibly for the evolution of life on Earth. As the current article shows, boron has been proven to be an important trace mineral because it (1) is essential for the growth and maintenance of bone; (2) greatly improves wound healing; (3) beneficially impacts the body’s use of estrogen, testosterone, and vitamin D; (4) boosts magnesium absorption; (5) reduces levels of inflammatory biomarkers, such as high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor α (TNF-α); (6) raises levels of antioxidant enzymes, such as superoxide dismutase (SOD), catalase, and glutathione peroxidase; (7) protects against pesticide-induced oxidative stress and heavy-metal toxicity; (8) improves the brains electrical activity, cognitive performance, and short-term memory for elders; (9) influences the formation and activity of key biomolecules, such as S-adenosyl methionine (SAM-e) and nicotinamide adenine dinucleotide (NAD+); (10) has demonstrated preventive and therapeutic effects in a number of cancers, such as prostate, cervical, and lung cancers, and multiple and non-Hodgkin’s lymphoma; and (11) may help ameliorate the adverse effects of traditional chemotherapeutic agents. In none of the numerous studies conducted to date, however, do boron’s beneficial effects appear at intakes > 3 mg/d. No estimated average requirements (EARs) or dietary reference intakes (DRIs) have been set for boron—only an upper intake level (UL) of 20 mg/d for individuals aged ≥ 18 y. The absence of studies showing harm in conjunction with the substantial number of articles showing benefits support the consideration of boron supplementation of 3 mg/d for any individual who is consuming a diet lacking in fruits and vegetables or who is at risk for or has osteopenia; osteoporosis

  16. The Role of Porphyrin-Free-Base in the Electronic Structures and Related Properties of N-Fused Carbazole-Zinc Porphyrin Dye Sensitizers

    Directory of Open Access Journals (Sweden)

    Xing-Yu Li

    2015-11-01

    Full Text Available Dye sensitizers can significantly affect power conversion efficiency of dye-sensitized solar cells (DSSCs. Porphyrin-based dyes are promising sensitizers due to their performances in DSSCs. Here, based upon a N-fused carbazole-zinc porphyrin-free-base porphyrin triad containing an ethynyl-linkage (coded as DTBC, the novel porphyrin dyes named DTBC-MP and DTBC-TP were designed by varying the porphyrin-free-base units in the π conjugation of DTBC in order to study the effect of porphyrin-free-base in the modification of electronic structures and related properties. The calculated results indicate that, the extension of the conjugate bridge with the porphyrin-free-base unit results in elevation of the highest occupied molecular orbital (HOMO energies, decrease of the lowest unoccupied molecular orbital (LUMO energies, reduction of the HOMO-LUMO gap, red-shift of the absorption bands, and enhancement of the absorbance. The free energy changes demonstrate that introducing more porphyrin-free-base units in the conjugate bridge induces a faster rate of electron injection. The transition properties and molecular orbital characters suggest that the different transition properties might lead to a different electron injection mechanism. In terms of electronic structure, absorption spectra, light harvesting capability, and free energy changes, the designed DTBC-TP is a promising candidate dye sensitizer for DSSCs.

  17. Increase of (CdSe/ZnS)Cys quantum dot luminescence intensity in the presence of TPPS{sub 4} porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Parra, Gustavo G.; Borissevitch, Iouri E. [Universidade de Sao Paulo (FFCLRP/USP), Ribeirao Preto, SP (Brazil). Fac. de Filosofia, Ciencias e Letras de Ribeirao Preto. Dept. de Fisica; Kuzmin, Vladimir A. [Emanuel Institute of Biophysical Chemistry, RAS-RU, Moscow (Russian Federation); Oleinikov, Vladimir A. [Shemyakin and Ovchinnikov Institute of Biooganic Cemistry, RAS-RU, Moscow (Russian Federation)

    2012-07-01

    Full text: Nanocrystal semiconductor particles or Quantum Dots (QD) possess extraordinary photophysical characteristics, such as extreme high fluorescence quantum yield and optical absorption and very narrow fluorescence band, which can be easily shifted by changing of QD particle size. Due to these characteristics, QD is promising for fluorescence cancer diagnostics and photodynamic treatment. The efficiency of these processes can be in- creased by energy transfer between QD and classic fluorescence probes and photosensitizers (PS). In this work we present on the study of the increase of (CdSe/ZnS)Cys quantum dot luminescence intensity, stimulated by interaction with TPPS{sub 4} porphyrin. The optical absorption and steady-state and time-resolved fluorescence techniques were employed. Water soluble QD (CdSe/ZnS) with emission at 580 nm, functionalized with cysteine (Cys), were studied. TPPS{sub 4} porphyrin was used as a stimulator of QD luminescence. All experiments were realized in PBS buffer (pH 7.3; 7.5 mM) in Milli-Q quality water. The TPPS{sub 4} adding into the QD solutions until the 5{mu}M concentration produced an increase in QD luminescence intensity and lifetime, while for TPPS{sub 4} concentrations higher than 20{mu}M the reduction of the fluorescence intensity was observed, the emission spectra and fluorescence decays profile being unchanged. This effect can not be due to the electrostatic interaction between (CdSe/ZnS)Cys and TPPS{sub 4} because both, (CdSe/ZnS)Cys and TPPS{sub 4}, are negatively charged. We suppose that TPPS{sub 4} porphyrin interacts directly with QD (ZnS) shell, reducing the dangling bound number. This reduction decreases, in turn, the probability of nonradiative ways of the excitation energy dissipation. When the majority of dangling bound is occupied by the TPPS{sub 4} molecules, the effect of QD luminescence reduction (quenching) by porphyrin predominates, probably, via the energy transfer from QD to TPPS{sub 4}. However

  18. Development of Smart Phthalocyanine-based Photosensitizers for Photodynamic Therapy

    Science.gov (United States)

    Chow, Yun Sang

    Phthalocyanines are versatile functional dyes that have shown great potential in cancer theranostics, especially in photodynamic therapy (PDT). This research work aims to develop "smart" phthalocyanine-based photosensitizers for targeted PDT. This thesis describes the synthesis, spectroscopic characterization, photophysical properties, and in vitro photodynamic activities of several series of carefully designed phthalocyanine-based photosensitizers. Chapter 1 presents an overview of PDT, including its historical development, photophysical mechanisms, and biological mechanisms. Various classes of photosensitizers are introduced with emphasis putting on phthalocyanines, which exhibit ideal characteristics of photosensitizers for PDT. In recent years, several approaches have been used to develop photosensitizers with higher tumor selectivity and minimal skin photosensitivity after PDT. Activatable photosensitizers can provide a "turn on" mechanism to offer an additional control of the specificity of treatment. Photosensitizers can also work cooperatively with the tumor-targeting groups or anticancer drugs so as to achieve targeted or dual therapy, which can enhance the efficacy of PDT. The novel approaches mentioned above have been widely used and combined to form multi-functional photosensitizing agents. These novel concepts and development of PDT are discussed and illustrated with relevant examples at the end of this chapter. To minimize the prolonged skin photosensitivity, photosensitizers that can only be activated by tumor-associated stimuli have been developed. Due to the abnormal metabolism in tumor tissues, their surface usually exhibits a lower pH compared to that of the normal tissues. Also, the pH difference between the intracellular and the physiological environment provides a pH-activation mechanism. Chapter 2 presents the synthesis and spectroscopic characterization of a pH-responsive zinc(II) phthalocyanine tetramer, in which the phthalocyanine units

  19. Nano boron nitride flatland.

    Science.gov (United States)

    Pakdel, Amir; Bando, Yoshio; Golberg, Dmitri

    2014-02-07

    Recent years have witnessed many breakthroughs in research on two-dimensional (2D) nanomaterials, among which is hexagonal boron nitride (h-BN), a layered material with a regular network of BN hexagons. This review provides an insight into the marvellous nano BN flatland, beginning with a concise introduction to BN and its low-dimensional nanostructures, followed by an overview of the past and current state of research on 2D BN nanostructures. A comprehensive review of the structural characteristics and synthetic routes of BN monolayers, multilayers, nanomeshes, nanowaves, nanoflakes, nanosheets and nanoribbons is presented. In addition, electronic, optical, thermal, mechanical, magnetic, piezoelectric, catalytic, ecological, biological and wetting properties, applications and research perspectives for these novel 2D nanomaterials are discussed.

  20. Metal interactions with boron clusters

    International Nuclear Information System (INIS)

    Grimes, R.N.

    1982-01-01

    This book presents information on the following topics: the structural and bonding features of metallaboranes and metallacarboranes; transition-metal derivatives of nido-boranes and some related species; interactions of metal groups with the octahydrotriborate (1-) anion, B 3 H 8 ; metallaboron cage compounds of the main group metals; closo-carborane-metal complexes containing metal-carbon and metal-boron omega-bonds; electrochemistry of metallaboron cage compounds; and boron clusters with transition metal-hydrogen bonds

  1. Boron diffusion in silicon devices

    Science.gov (United States)

    Rohatgi, Ajeet; Kim, Dong Seop; Nakayashiki, Kenta; Rounsaville, Brian

    2010-09-07

    Disclosed are various embodiments that include a process, an arrangement, and an apparatus for boron diffusion in a wafer. In one representative embodiment, a process is provided in which a boric oxide solution is applied to a surface of the wafer. Thereafter, the wafer is subjected to a fast heat ramp-up associated with a first heating cycle that results in a release of an amount of boron for diffusion into the wafer.

  2. Tunable photophysical processes of porphyrin macrocycles on the surface of ZnO nanoparticles

    KAUST Repository

    Parida, Manas R.

    2015-01-23

    We investigated the impact of the molecular structure of cationic porphyrins on the degree of electrostatic interactions with zinc oxide nanoparticles (ZnO NPs) using steady-state and time-resolved fluorescence and transient absorption spectroscopy. Our results demonstrate that the number of cationic pyridinium units has a crucial impact on the photophysics of the porphyrin macrocycle. Fluorescence enhancement, relative to initial free porphyrin fluorescence, was found to be tuned from 3.4 to 1.3 times higher by reducing the number of cationic substituents on the porphyrin from 4 to 2. The resulting enhancement of the intensity of the fluorescence is attributed to the decrease in the intramolecular charge transfer (ICT) character between the porphyrin cavity and its meso substituent. The novel findings reported in this work provide an understanding of the key variables involved in nanoassembly, paving the way toward optimizing the interfacial chemistry of porphyrin-ZnO NP assembly for photodynamic therapy and energy conversion.

  3. Substituted group and side chain effects for the porphyrin and zinc(II)–porphyrin derivatives: A DFT and TD-DFT study

    International Nuclear Information System (INIS)

    Tai, Chin-Kuen; Chuang, Wen-Hua; Wang, Bo-Cheng

    2013-01-01

    The DFT/B3LYP/LANL2DZ and TD-DFT calculations have been performed to generate the optimized structures, electronic and photo-physical properties for the porphyrin and zinc(II)–porphyrin (metalloporphyrin) derivatives. The substituted group and side chain effects for these derivatives are discussed in this study. According to the calculation results, the side chain moiety extends the π-delocalization length from the porphyrin core to the side chain moiety. The substituted group with a stronger electron-donating ability increases the energy level of highest occupied molecular orbital (E HOMO ). The side chain moiety with a lower resonance energy decreases E HOMO , the energy level of the lowest unoccupied molecular orbital (E LUMO ), and the energy gap (E g ) between HOMO and LUMO in the porphyrin and zinc(II)–porphyrin derivatives. The natural bonding orbital (NBO) analysis determines the possible electron transfer mechanism from the electron-donating to -withdrawing groups (the side chain moiety) in these porphyrin derivatives. The projected density of state (PDOS) analysis shows that the electron-donating group affects the electron density distribution in both HOMO and LUMO, and the side chain moiety influence the electron density distribution in LUMO. The calculated photo-physical properties (absorption wavelengths and the related oscillator strength, f) in dichloromethane environment for porphyrin and zinc(II)–porphyrin derivatives have been simulated by using the TD-DFT method within the Polarizable Continuum Model (PCM). The present of both of the substituted group and the side chain moiety in these derivatives results in a red shift and broadening of the range of the absorption peaks of the Q/Soret band as compared to porphin. -- Highlights: • Side chain moiety extends the π-delocalization for the porphyrins. • Substituted group increases the energy of highest occupied molecular orbital. • Side chain moiety influences the Q/Soret band of

  4. Singlet oxygen: photosensitized generation, detection and reaction with organic molecules

    International Nuclear Information System (INIS)

    Barik, Atanu; Indira Priyadarsini, K.; Hari Mohan; Bajaj, P.N.; Sapre, A.V.; Mittal, J.P.; Mukherjee, T.

    2006-10-01

    Singlet molecular oxygen ( 1 O 2 ) is an excited state of molecular oxygen, having antiparallel spin in the same π antibonding orbital. The study of singlet oxygen production and reactivity has emerged as a rich and diverse area, with implication in diverse fields, such as synthetic chemistry, polymer chemistry, photodynamic therapy, etc. There are several known methods to produce singlet oxygen, and also various techniques employed to detect it. Out of these, photosensitization method is the most popular one. In this article, photosensitized production of singlet oxygen from triplet oxygen and photosensitizers in presence of light, and its detection by the infrared luminescence at 1270 nm have been presented. Further, some results using different types of photosensitizers, effect of solvent on singlet oxygen quantum yields and lifetime have been discussed. The quenching rate constants of singlet oxygen have been determined with different types of organic molecules such as derivatives of thiourea and its analogues, hydroxy indoles and antioxidants and the results have been presented. (author)

  5. Photosensitive N channel MOSFET device on silicon on sapphire substrate

    International Nuclear Information System (INIS)

    Le Goascoz, V.; Borel, J.

    1975-01-01

    An anomalous behavior of the N channel output current characteristic in a SOS MOSFET with a floating bulk is described. Such a phenomenon can be used in a photosensitive device with internal gain. Such devices can be used on SOS substrates to achieve integrated circuits with high insulating voltages and data transmission by optical means [fr

  6. Photochemical events during photosensitization of colloidal ZnO ...

    Indian Academy of Sciences (India)

    The photosensitization of colloidal ZnO nanoparticles with riboflavin (RF) was investigated using absorption, fluorescence spectroscopic measurements and time resolved fluorescence measurements. Riboflavin adsorbed strongly on the surface of ZnO nanoparticles. Apparent association constant was obtained from the ...

  7. Photosensitive filler minimizes internal stresses in epoxy resins

    Science.gov (United States)

    Dillon, J. N.

    1967-01-01

    Photosensitive filler is added to curable epoxy resins to minimize stress from internal shrinkage during curing or polymerization. Cinnamic acid resins and cinnamal ketones may be added in the amount of 1 to 3 percent by weight of the resin mixture.

  8. DFT application for chlorin derivatives photosensitizer drugs modeling

    Science.gov (United States)

    Machado, Neila; Carvalho, B. G.; Téllez Soto, C. A.; Martin, A. A.; Favero, P. P.

    2018-04-01

    Photodynamic therapy is an alternative form of cancer treatment that meets the desire for a less aggressive approach to the body. It is based on the interaction between a photosensitizer, activating light, and molecular oxygen. This interaction results in a cascade of reactions that leads to localized cell death. Many studies have been conducted to discover an ideal photosensitizer, which aggregates all the desirable characteristics of a potent cell killer and generates minimal side effects. Using Density Functional Theory (DFT) implemented in the program Vienna Ab-initio Simulation Package, new chlorin derivatives with different functional groups were simulated to evaluate the different absorption wavelengths to permit resonant absorption with the incident laser. Gaussian 09 program was used to determine vibrational wave numbers and Natural Bond Orbitals. The chosen drug with the best characteristics for the photosensitizer was a modified model of the original chlorin, which was called as Thiol chlorin. According to our calculations it is stable and is 19.6% more efficient at optical absorption in 708 nm in comparison to the conventional chlorin e6. Vibrational modes, optical and electronic properties were predicted. In conclusion, this study is an attempt to improve the development of new photosensitizer drugs through computational methods that save time and contribute to decrease the numbers of animals for model application.

  9. Drug-delivery and multifunction possibilities of hypocrellin photosensitizers

    Directory of Open Access Journals (Sweden)

    Hong Deng

    2015-01-01

    Full Text Available Photodynamic therapy (PDT has been a routine treatment of tumors and some microvascular diseases, but clinically available photosensitizers are still scarce. Among all kinds of photosensitizers, hypocrellins possess the most characteristics of ideal photosensitizers, such as, high photo-activity but low dark toxicity, fast clearance from tissues. This review is focused on two main topics, drug-delivery problem of hypocrellins and how the environment-sensitive fluorescence of hypocrellins was used for recognition of various biomolecules. Drug-delivery of hypocrellins was mainly achieved in two strategies — preparing the drug-delivery vehicles and finding quantitatively amphiphilic derivatives. Hypocrellin fluorescence originated from the intramolecular proton transfer is very distinct from other kinds of photosensitizers. Recently, it was proved that quantitative hypocrellin fluorescence could not only recognize various biomolecules, including proteins, polysaccharides and lipids, but also distinguish the specific binding from nonspecific binding with some kind of biomolecules. Meantime, hypocrellin fluorescence was pH-sensitive. It is known that tumor cells or tissues have the features of a large amount of lipid, neonatal collagen, over-expression of polysaccharides, and lower pH values compared to normal tissues. According to the relative but not absolute specificity, further studies on quantitative recognition of various biomolecules at a cellular level, may find a new clue to treat tumors by joint usage of photodynamic diagnosis (PDD and PDT.

  10. Development of proportional counters using photosensitive gases and liquids

    International Nuclear Information System (INIS)

    Anderson, D.F.

    1984-10-01

    An introduction to the history and to the principle of operation of wire chambers using photosensitive gases and liquids is presented. Their use as light sensors coupled to Gas Scintillation Proportional Counters and BaF 2 , as well as their use in Cherenkov Ring imaging, is discussed in some detail. 42 references, 21 figures

  11. Systemic reduction of rice blast by means of photosensitizers

    Science.gov (United States)

    Acquired disease resistance of plants may be induced by exogenous reactive oxygen species or their sources. Certain compounds (photosensitizers) produce ROS at the expense of light energy. This study used photodynamic dyes bengal rose and methylene blue, which yield singlet oxygen, and mercaptopyrid...

  12. Boron Fullerenes: A First-Principles Study

    Directory of Open Access Journals (Sweden)

    Gonzalez Szwacki Nevill

    2007-01-01

    Full Text Available AbstractA family of unusually stable boron cages was identified and examined using first-principles local-density functional method. The structure of the fullerenes is similar to that of the B12icosahedron and consists of six crossing double-rings. The energetically most stable fullerene is made up of 180 boron atoms. A connection between the fullerene family and its precursors, boron sheets, is made. We show that the most stable boron sheets are not necessarily precursors of very stable boron cages. Our finding is a step forward in the understanding of the structure of the recently produced boron nanotubes.

  13. Synthesis, Characterization, and Reactivities of Manganese(V)-Oxo Porphyrin Complexes

    OpenAIRE

    Song, Woon Ju; Seo, Mi Sook; George, Serena DeBeer; Ohta, Takehiro; Song, Rita; Kang, Min-Jung; Tosha, Takehiko; Kitagawa, Teizo; Solomon, Edward I.; Nam, Wonwoo

    2007-01-01

    The reactions of manganese(III) porphyrin complexes with terminal oxidants, such as m-chloroperbenzoic acid, iodosylarenes, and H2O2, produced high-valent manganese(V)-oxo porphyrins in the presence of base in organic solvents at room temperature. The manganese(V)-oxo porphyrins have been characterized with various spectroscopic techniques, including UV-vis, EPR, 1H and 19F NMR, resonance Raman, and X-ray absorption spectroscopy. The combined spectroscopic results indicate that the manganese(...

  14. Template-directed synthesis of flexible porphyrin nanocage and nanorings via one-step olefin metathesis.

    Science.gov (United States)

    Zhu, Bin; Chen, Huanxin; Lin, Wei; Ye, Yang; Wu, Jing; Li, Shijun

    2014-10-29

    We describe the fabrication of a suite of flexible porphyrin cages and nanorings from a simple tetraalkene-derived zinc porphyrin monomer via a highly efficient template-directed strategy. The zinc porphyrin monomers were preorganized together by coordination with N atoms of multidentate ligands. Subsequent one-step olefin metathesis furnished a bisporphyrin cage, a triporphyrin nanoring, and a hexaporphyrin nanoring. In the case of the hexaporphyrin nanoring, 24 terminal olefins from six porphyrin monomers reacted with each other to form 12 new double bonds, delivering the final product. The triporphyrin and hexaporphyrin nanorings were further employed as hosts to encapsulate C60 and C70.

  15. Porphyrin as an ideal biomarker in the search for extraterrestrial life.

    Science.gov (United States)

    Suo, Zhiyong; Avci, Recep; Schweitzer, Mary Higby; Deliorman, Muhammedin

    2007-08-01

    A key issue in astrobiological research is identifying target molecules that are unambiguously biological in origin and can be easily detected and recognized. We suggest porphyrin derivatives as an ideal target, because these chromophores are global in distribution and found in virtually all living organisms on Earth, including microorganisms that may approximate the early evolution of life on Earth. We discuss the inherent qualities that make porphyrin ideally suited for astrobiological research and discuss methods for detecting porphyrin molecules in terrestrial sedimentary environments. We present preliminary data to support the use of ToFSIMS as a powerful technique in the identification of porphyrins.

  16. In vivo quantification of photosensitizer concentration using fluorescence differential path-length spectroscopy : influence of photosensitizer formulation and tissue location

    NARCIS (Netherlands)

    de Visscher, Sebastiaan A. H. J.; Witjes, Max J. H.; Kascakova, Slavka; Sterenborg, Henricus J. C. M.; Robinson, Dominic J.; Roodenburg, Jan L. N.; Amelink, Arjen

    In vivo measurement of photosensitizer concentrations may optimize clinical photodynamic therapy (PDT). Fluorescence differential path-length spectroscopy (FDPS) is a non-invasive optical technique that has been shown to accurately quantify the concentration of Foscan (R) in rat liver. As a next

  17. Emulating porphyrins with a rippled multivacancy graphene system

    Science.gov (United States)

    Mombrú, Dominique; Faccio, Ricardo; Mombrú, Alvaro W.

    2018-04-01

    The interaction between a complex porphyrin-like system formed by an iron atom and multivacant graphene layer and O2, CO and CO2 molecules is studied, using Density Functional Theory (DFT) calculations. The multivacancy graphene system used for this study, consists in the removal of a 1,4-dimethybenzene-like moiety, in a 6 × 6 supercell. This removal and the structural optimization subsequently performed, yield to a biaxial vacancy, where the location of an iron atom embedded in it, lead to a system with resemblance to iron-porphyrin systems. This similar structure could be used to form complexes where gas molecules are allowed to interact with these iron-octavacant graphene systems. The study focuses on the structure of the system and the net magnetic moment for different gas molecules: O2, CO2 and CO. Rippling in the vacant graphene is enhanced through this interaction.

  18. Enhanced solar energy collection in porphyrin based photoconversion schemes

    Science.gov (United States)

    Gust, D.; Moore, T. A.

    1983-02-01

    A series of carotenoporphyrins whose conformations varied from folded (with the carotenoid (PI)-electron system stacked over that of the porphyrin) to extended (with the two chromophores widely separated) were studied. The conformations were determined by high resolution proton NMR studies. Laser flash spectroscopy revealed triplet energy transfer from porphyrin to carotenoid. Three distinct pathways for such transfer were discovered: (1) static through space transfer which does not require significant intramolecular motions; (2) dynamic through space transfer mediated by intramolecular motions; (3) triplet transfer mediated by the chemical bonds joining the chromophores. pulse radiolysis and fluorescence quenching of these ethers and related carotenoporphyrins revealed electron transfer in the systems. It is demonstrated that the natural carotenoid functions of photoprotection from singlet oxygen damage and antenna function can be mimicked by synthetic molecules, and therefore, in principle can be applied to artificial solar energy conversion systems.

  19. Facile Preparation of Hybrid Zinc Porphyrin Dendrimer Using Coordination Complex

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Go-Eun; Shin, Eun Ju [Sunchon National University, Suncheon (Korea, Republic of)

    2016-03-15

    Porphyrins and metalloporphyrins have been investigated extensively due to their important role in natural photosynthesis, strong absorption in visible region, good light-harvesting properties, unique photophysical and electrochemical properties, and the development of simple synthetic routes for various derivatives. Dendrimers have globular structure with branches of repeating units and wide diversity of the architecture because their size, shape, and functionalities can be tailored. Numerous dendrimers have been designed and synthesized for various applications ranging from catalyst to drug delivery. Both pyridine dendrons Py-PD and Py-AD were successfully coordinated at axial position on central zinc metal cation in zinc porphyrin dendrimers ZnP-AD, ZnP-AD2, or ZnP-AD4. Therefore, it was proven that the formation of axial coordination complex between metal-centered dendrimer and ligand-containing dendron provides another facile method for the preparation of new hybrid dendrimer.

  20. Synthesis and anion binding properties of porphyrins and related compounds

    KAUST Repository

    Figueira, Flávio

    2016-12-02

    Over the last two decades the preparation of pyrrole-based receptors for anion recognition has attracted considerable attention. In this regard porphyrins, phthalocyanines and expanded porphyrins have been used as strong and selective receptors while the combination of those with different techniques and materials can boost their applicability in different applications as chemosensors and extracting systems. Improvements in the field, including the synthesis of this kind of compounds, can contribute to the development of efficient, cheap, and easy-to-prepare anion receptors. Extensive efforts have been made to improve the affinity and selectivity of these compounds and the continuous expansion of related research makes this chemistry even more promising. In this review, we summarize the most recent developments in anion binding studies while outlining the strategies that may be used to synthesize and functionalize these type of macrocycles. © 2016 World Scientific Publishing Company.

  1. Synthesis and Spectroscopic Characterization of Two Tetrasubstituted Cationic Porphyrin Derivatives

    Directory of Open Access Journals (Sweden)

    Newton M. Barbosa Neto

    2011-07-01

    Full Text Available An imidazolium tetrasubstituted cationic porphyrin derivative (the free base and its Zn(II complex with five-membered heterocyclic groups in the meso-positions were synthesized using microwave irradiation, and the compounds obtained characterized by 1H-NMR and mass spectrometry. We observed that under microwave irradiation the yield is similar to when the synthesis is performed under conventional heating, however, the time required to prepare the porphyrins decreases enormously. In order to investigate the electronic state of these compounds, we employed UV-Vis and fluorescence spectroscopy combined with quantum chemical calculations. The results reveal the presence, in both compounds, of a large number of electronic states involving the association between the Soret and a blue-shifted band. The Soret band in both compounds also shows a considerable solvent dependence. As for emission, these compounds present low quantum yield at room temperature and no solvent influence on the fluorescence spectra was observed.

  2. Gold-phosphine-porphyrin as potential metal-based theranostics.

    Science.gov (United States)

    Tasan, Semra; Licona, Cynthia; Doulain, Pierre-Emmanuel; Michelin, Clément; Gros, Claude P; Le Gendre, Pierre; Harvey, Pierre D; Paul, Catherine; Gaiddon, Christian; Bodio, Ewen

    2015-01-01

    Two new gold-phosphine-porphyrin derivatives were synthesized and fully characterized, and their photophysical properties investigated along a water-soluble analog. The cytotoxicity of the compounds was tested on cancer cells (HCT116 and SW480), and their cell uptake was followed by fluorescence microscopy in vitro (on SW480). The proof that the water-soluble gold-phosphine-porphyrin is a biologically active compound that can be tracked in vitro was clearly established, especially concerning the water-soluble analog. Some preliminary photodynamic therapy (PDT) experiments were also performed. They highlight a dramatic increase of the cytotoxicity when the cells were illuminated for 30 min with white light.

  3. Porphyrin-Based Carbon Dots for Photodynamic Therapy of Hepatoma.

    Science.gov (United States)

    Li, Yang; Zheng, Xiaohua; Zhang, Xiaoyu; Liu, Shi; Pei, Qing; Zheng, Min; Xie, Zhigang

    2017-01-01

    Porphyrin-containing carbon dots (CDs) possess ultrasmall size, excellent water solubility, and photostability. These CDs can effectively generate cytotoxic singlet oxygen upon irradiation, and induce the cell apoptosis. Photodynamic ability of CDs inhibits the growth of hepatoma. This work not only sheds light on developing functional carbon dots, but also highlights the importance of special-structure precursor molecules in synthesizing functional CDs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Optical sensing system for ATP using porphyrin-alkaloid conjugates

    Czech Academy of Sciences Publication Activity Database

    Kejík, Z.; Záruba, K.; Machalík, D.; Šebek, Jiří; Dian, J.; Pataridis, S.; Volka, K.; Král, Vladimír

    -, č. 14 (2006), s. 1533-1539 ISSN 1359-7345 R&D Projects: GA MŠk(CZ) LC512; GA ČR(CZ) GA203/03/0900; GA ČR(CZ) GA203/06/1038 Grant - others:CIDNA(XE) NMP4-CT-2003-505669 Institutional research plan: CEZ:AV0Z40550506 Keywords : optical sensing * ATP * porphyrin Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.521, year: 2006

  5. In Silico Study, Synthesis, and Cytotoxic Activities of Porphyrin Derivatives

    Directory of Open Access Journals (Sweden)

    Fransiska Kurniawan

    2018-01-01

    Full Text Available Five known porphyrins, 5,10,15,20-tetrakis(p-tolylporphyrin (TTP, 5,10,15,20-tetrakis(p-bromophenylporphyrin (TBrPP, 5,10,15,20-tetrakis(p-aminophenylporphyrin (TAPP, 5,10,15-tris(tolyl-20-mono(p-nitrophenylporphyrin (TrTMNP, 5,10,15-tris(tolyl-20-mono(p-aminophenylporphyrin (TrTMAP, and three novel porphyrin derivatives, 5,15-di-[bis(3,4-ethylcarboxymethylenoxyphenyl]-10,20-di(p-tolylporphyrin (DBECPDTP, 5,10-di-[bis(3,4-ethylcarboxymethylenoxyphenyl]-15,20-di-(methylpyrazole-4-ylporphyrin (cDBECPDPzP, 5,15-di-[bis(3,4-ethylcarboxymethylenoxyphenyl]-10,20-di-(methylpyrazole-4-ylporphyrin (DBECPDPzP, were used to study their interaction with protein targets (in silico study, and were synthesized. Their cytotoxic activities against cancer cell lines were tested using 3-(4,5-dimetiltiazol-2-il-2,5-difeniltetrazolium bromide (MTT assay. The interaction of porphyrin derivatives with carbonic anhydrase IX (CAIX and REV-ERBβ proteins were studied by molecular docking and molecular dynamic simulation. In silico study results reveal that DBECPDPzP and TrTMNP showed the highest binding interaction with REV- ERBβ and CAIX, respectively, and both complexes of DBECPDPzP-REV-ERBβ and TrTMNP-CAIX showed good and comparable stability during molecular dynamic simulation. The studied porphyrins have selective growth inhibition activities against tested cancer cells and are categorized as marginally active compounds based on their IC50.

  6. Cobalt Porphyrin-Polypyridyl Surface Coatings for Photoelectrosynthetic Hydrogen Production.

    Science.gov (United States)

    Beiler, A M; Khusnutdinova, D; Wadsworth, B L; Moore, G F

    2017-10-16

    Hybrid materials that link light capture and conversion technologies with the ability to drive reductive chemical transformations are attractive as components in photoelectrosynthetic cells. We show that thin-film polypyridine surface coatings provide a molecular interface to assemble cobalt porphyrin catalysts for hydrogen evolution onto a visible-light-absorbing p-type gallium phosphide semiconductor. Spectroscopic techniques, including grazing angle attenuated total reflection Fourier transform infrared spectroscopy, confirm that the cobalt centers of the porphyrin macrocycles coordinate to pyridyl nitrogen sites of the organic surface coating. The cobalt porphyrin surface concentration and fraction of pyridyl sites coordinated to a cobalt center are quantified using complementary methods of ellipsometry, inductively coupled plasma mass spectrometry, and X-ray photoelectron spectroscopy. In aqueous solutions under simulated solar illumination the modified cathode is photochemically active for hydrogen production, generating the product gas with near-unity Faradaic efficiency at a rate of ≈10 μL min -1 cm -2 when studied in a three-electrode configuration and polarized at the equilibrium potential of the H + /H 2 couple. This equates to a photoelectrochemical hydrogen evolution reaction activity of 17.6 H 2 molecules s -1 Co -1 , the highest value reported to date for a molecular-modified semiconductor. Key features of the functionalized photocathode include (1) the relative ease of synthetic preparation made possible by application of an organic surface coating that provides molecular recognition sites for immobilizing the cobalt porphyrin complexes at the semiconductor surface and (2) the use of visible light to drive cathodic fuel-forming reactions in aqueous solutions with no added organic acids or sacrificial chemical reductants.

  7. Porphyrin-kaolinite as efficient catalyst for oxidation reactions.

    Science.gov (United States)

    Bizaia, Natalia; de Faria, Emerson H; Ricci, Gustavo P; Calefi, Paulo S; Nassar, Eduardo J; Castro, Kelly A D F; Nakagaki, Shirley; Ciuffi, Katia J; Trujillano, Raquel; Vicente, Miguel A; Gil, Antonio; Korili, Sophia A

    2009-11-01

    The preparation, characterization, and application in oxidation reactions of new biomimetic catalysts are reported. Brazilian Sao Simao kaolinite clay has been functionalized with [meso-tetrakis(pentafluorophenyl)porphinato]iron(III), Fe(TPFPP). To obtain the functionalized clay, the natural clay was purified by dispersion-sedimentation, expanded by insertion of dimethyl sulfoxide (DMSO), and functionalized with amino groups by substitution of DMSO with ethanolamine. These previous steps allowed clay functionalization with Fe(TPFPP), leading to a layered material with a basal spacing of 10.73 A. Clay functionalization with the porphyrin was confirmed by formation of the secondary amine, as demonstrated by FTIR bands at 3500-3700 cm(-1). UV-vis spectroscopy revealed a red shift in the Soret band of the iron porphyrin in the functionalized material as compared to the parent iron porphyrin catalyst in solution, indicating Fe(III)P --> Fe(II)P reduction. The catalytic performance of the functionalized clay was evaluated in the epoxidation of cyclooctene, with complete selectivity for the epoxide (100% epoxide yield), and ketonization of cyclohexane, cyclohexanone being the major product. The novel catalyst was also evaluated in the Baeyer-Villiger (BV) oxidation of cyclohexanone, with 85% conversion of cyclohexanone in epsilon-caprolactone, with total selectivity to epsilon-caprolactone.

  8. Future boronated molecules for neutron capture therapy

    International Nuclear Information System (INIS)

    Soloway, A.H.; Alam, F.; Barth, R.F.

    1986-01-01

    The ability of several boron compounds to localize in tumor cells is examined. A number of first and second generation compounds which were not synthesized specifically for localization are described. Among these are the boron hydrides and boranes. A third generation of boron compounds are designed for selective localization. These fall into two groups: relatively small organic compounds and boronated antibodies, both of which are discussed here

  9. Compression and Associated Properties of Boron Carbide

    Science.gov (United States)

    2008-12-01

    Klandadze, G.I., and Eristavi, A.M., 1999: IR- Active Phonons and Structure Elements of Isotope - Enriched Boron Carbide, J. Sol. State Chem. 154, 79- 86...COMPRESSION AND ASSOCIATED PROPERTIES OF BORON CARBIDE D. P. Dandekar*and J. A. Ciezak Army Research Laboratory, APG, MD 21005 M. Somayazulu...of the observed loss of shear strength in boron carbide under plane shock wave compression to amorphization in boron carbide under triaxial stress

  10. Lattice vibrations in α-boron

    International Nuclear Information System (INIS)

    Richter, W.

    1976-01-01

    α-rhombohedral boron is the simplest boron modification, with only 12 atoms per unit cell. The boron atoms are arranged in B 12 icosahedra, which are centered at the lattice points of a primitive rhombohedral lattice. The icosahedra are slightly deformed, as the five-fold symmetry of the ideal icosahedron is incompatible with any crystal structure. The lattice dynamics of α-boron are discussed in terms of the model developed by Weber and Thorpe. (Auth.)

  11. Synthesis of oligomeric boron-containing phospolyols

    International Nuclear Information System (INIS)

    Bondarenko, S.N.; Khokhlova, T.V.; Orlova, S.A.; Tuzhikov, O.I.

    2006-01-01

    Structure is investigated and reactivity of oligomeric boron-containing phospolyols is studied. Oligomeric boron-containing compound interacts with ethylene glycol, diethylene glycol, glycerol, 1,4-butandiol with formation of linear boron-containing phospolyols. Reactions proceed in noncatalytic conditions with stoichiometric quantities of reagents at 170-200 Deg C in inert gas media. Boron-containing phospolyols are viscous uncolored liquids, their physicochemical characteristics are represented [ru

  12. Structures, stability, mechanical and electronic properties of a-boron and its twined brother a*-boron

    OpenAIRE

    He, Chaoyu; Zhong, Jianxin

    2013-01-01

    The structures, stability, mechanical and electronic properties of a-boron and its twined brother a*-boron have been studied by first-principles calculations. Both a-boron and a*-boron consist of equivalent icosahedra B12 clusters in different connecting configurations of "3S-6D-3S" and "2S-6D-4S", respectively. The total energy calculations show that a*-boron is less stable than a-boron but more favorable than beta-boron and Gamma-boron at zero pressure. Both a-boron and a*-boron are confirm...

  13. Ionic self-assembly of porphyrin nanostructures on the surface of charge-altered track-etched membranes

    CSIR Research Space (South Africa)

    Mongwaketsi, N

    2010-01-01

    Full Text Available and Sn(IV) tetrakis(4-pyridyl)porphyrin were used to synthesize ionic self-assembled porphyrin nanorods. The track-etched membranes surface charge was changed from negative to positive using polyethyleneimine. The porphyrin nanorods were either filtered...

  14. Novel photosensitizers trigger rapid death of malignant human cells and rodent tumor transplants via lipid photodamage and membrane permeabilization.

    Directory of Open Access Journals (Sweden)

    Mikhail M Moisenovich

    Full Text Available BACKGROUND: Apoptotic cascades may frequently be impaired in tumor cells; therefore, the approaches to circumvent these obstacles emerge as important therapeutic modalities. METHODOLOGY/PRINCIPAL FINDINGS: Our novel derivatives of chlorin e(6, that is, its amide (compound 2 and boronated amide (compound 5 evoked no dark toxicity and demonstrated a significantly higher photosensitizing efficacy than chlorin e(6 against transplanted aggressive tumors such as B16 melanoma and M-1 sarcoma. Compound 5 showed superior therapeutic potency. Illumination with red light of mammalian tumor cells loaded with 0.1 µM of 5 caused rapid (within the initial minutes necrosis as determined by propidium iodide staining. The laser confocal microscopy-assisted analysis of cell death revealed the following order of events: prior to illumination, 5 accumulated in Golgi cysternae, endoplasmic reticulum and in some (but not all lysosomes. In response to light, the reactive oxygen species burst was concomitant with the drop of mitochondrial transmembrane electric potential, the dramatic changes of mitochondrial shape and the loss of integrity of mitochondria and lysosomes. Within 3-4 min post illumination, the plasma membrane became permeable for propidium iodide. Compounds 2 and 5 were one order of magnitude more potent than chlorin e(6 in photodamage of artificial liposomes monitored in a dye release assay. The latter effect depended on the content of non-saturated lipids; in liposomes consisting of saturated lipids no photodamage was detectable. The increased therapeutic efficacy of 5 compared with 2 was attributed to a striking difference in the ability of these photosensitizers to permeate through hydrophobic membrane interior as evidenced by measurements of voltage jump-induced relaxation of transmembrane current on planar lipid bilayers. CONCLUSIONS/SIGNIFICANCE: The multimembrane photodestruction and cell necrosis induced by photoactivation of 2 and 5 are

  15. Photosensitization and phototherapy with furocoumarins: A quantum-chemical study

    International Nuclear Information System (INIS)

    Serrano-Perez, Juan Jose; Serrano-Andres, Luis; Merchan, Manuela

    2008-01-01

    The effect of electromagnetic radiation on biological objects extends from heating to complex photochemistry, and includes DNA alteration, that properly modified in damaged cells may entail beneficial effects. In this regard, psoralen + UV-A (PUVA) therapy, in which furocoumarins, psoralen-like chromophores, are used as photosensitizers and photoreactants with DNA bases, is one of the most promising strategies against a plethora of diseases. Understanding the underlying photochemical mechanisms is crucial to design effective drugs without undesired side effects. We have undertaken a quantum-mechanical study on the photophysics and photochemistry of furocoumarins, analyzing firstly the most efficient way in which the lowest excited triplet state, as protagonist of the photosensitizing action, is populated from the initially promoted singlet states, and secondly the basics of the formation of furocoumarin-DNA photoadducts

  16. Chlorin photosensitizers sterically designed to prevent self-aggregation.

    Science.gov (United States)

    Uchoa, Adjaci F; de Oliveira, Kleber T; Baptista, Mauricio S; Bortoluzzi, Adailton J; Iamamoto, Yassuko; Serra, Osvaldo A

    2011-11-04

    The synthesis and photophysical evaluation of new chlorin derivatives are described. The Diels-Alder reaction between protoporphyrin IX dimethyl ester and substituted maleimides furnishes endo-adducts that completely prevent the self-aggregation of the chlorins. Fluorescence, resonant light scattering (RLS) and (1)H NMR experiments, as well as X-ray crystallographic have demonstrated that the configurational arrangement of the synthesized chlorins prevent π-stacking interactions between macrocycles, thus indicating that it is a nonaggregating photosensitizer with high singlet oxygen (Φ(Δ)) and fluorescence (Φ(f)) quantum yields. Our results show that this type of synthetic strategy may provide the lead to a new generation of PDT photosensitizers.

  17. Surface Free Energy Determination of APEX Photosensitive Glass

    Directory of Open Access Journals (Sweden)

    William R. Gaillard

    2016-02-01

    Full Text Available Surface free energy (SFE plays an important role in microfluidic device operation. Photosensitive glasses such as APEX offer numerous advantages over traditional glasses for microfluidics, yet the SFE for APEX has not been previously reported. We calculate SFE with the Owens/Wendt geometric method by using contact angles measured with the Sessile drop technique. While the total SFE for APEX is found to be similar to traditional microstructurable glasses, the polar component is lower, which is likely attributable to composition. The SFE was modified at each stage of device fabrication, but the SFE of the stock and fully processed glass was found to be approximately the same at a value of 51 mJ·m−2. APEX exhibited inconsistent wetting behavior attributable to an inhomogeneous surface chemical composition. Means to produce more consistent wetting of photosensitive glass for microfluidic applications are discussed.

  18. Benzochloroporphyrin derivative photosensitizer-mediated photodynamic therapy for Ewing sarcoma.

    Science.gov (United States)

    Sun, Mengxiong; Zhou, Chenghao; Zeng, Hui; Yin, Fei; Wang, Zhuoying; Yao, Jianzhong; Hua, Yingqi; Cai, Zhengdong

    2016-07-01

    In this study, we evaluated the photodynamic efficacy of a new photosensitizer, benzochloroporphyrin derivative 18 (BCPD-18), in Ewing sarcoma. We found that BCPD-18 decreased the viability of TC-71 cells irradiated by 670nm laser in a concentration dependent manner. We also observed cells undergoing apoptosis as well as cell cycle arrest at the G2M phase after BCPD-18-mediated photodynamic therapy (BCPD-PDT). In addition, in vivo study (subcutaneous and orthotopic models) showed that BCPD-PDT reduced tumor size, tumor weight and tumor-bearing leg weight. After PDT, apoptosis was shown in vivo. Bax expression was increased, and Bcl-2 expression was decreased. This study provides evidence that BCPD-18 could probably be a useful photosensitizer in PDT for Ewing sarcoma. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Intrinsically photosensitive retinal ganglion cell function in relation to age

    DEFF Research Database (Denmark)

    Herbst, Kristina; Sander, Birgit; Lund-Andersen, Henrik

    2012-01-01

    The activity of melanopsin containing intrinsically photosensitive ganglion retinal cells (ipRGC) can be assessed by a means of pupil responses to bright blue (appr.480 nm) light. Due to age related factors in the eye, particularly, structural changes of the lens, less light reaches retina. The aim...... of this study was to examine how age and in vivo measured lens transmission of blue light might affect pupil light responses, in particular, mediated by the ipRGC....

  20. Rapid killing of bacteria by a new type of photosensitizer.

    Science.gov (United States)

    Zhang, Yaxin; Zheng, Ke; Chen, Zhuo; Chen, Jincan; Hu, Ping; Cai, Linrong; Iqbal, Zafar; Huang, Mingdong

    2017-06-01

    Photodynamic antimicrobial chemotherapy (PACT) uses non-traditional mechanisms (free radicals) and is a highly advocated method with promise of inactivating drug-resistance bacteria for local infections. However, there is no related drug used in clinical practice yet. Therefore, new photosensitizers for PACT are under active development. Here, we report the synthesis of a series of photosensitizers with variable positive charges (ZnPc(TAP) 4 n+ , n = 0, 4, 8, 12) and their inactivation against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The binding kinetics of ZnPc(TAP) 4 n+ to bacteria were measured by flow cytometer. Reactive oxygen species (ROS) generation mechanism of the photosensitizers was studied. The toxicity of these compounds to human blood cells was also evaluated. These compounds showed negligible toxicity against human erythocytes but potent bactericidal effects. The compound with 8 positive charges, ZnPc(TAP) 4 8+ , turned out to have the strongest antibacterial effect among this series of compounds, giving IC 50 value of 59 nM at a light dosage of 5 J/cm 2 toward E. coli. For a multi-resistant E. coli strain, ZnPc(TAP) 4 8+ decreased the bacteria load by 1000-fold at a concentration of 1 μM. Interestingly, ZnPc(TAP) 4 12+ , instead of ZnPc(TAP) 4 8+ , exhibited the highest amount of binding to bacteria. Flow cytometry studies showed that all PSs have fast binding onto bacteria, reaching saturated binding within 5 min. Mechanistically, ZnPc(TAP) 4 12+ generated ROS primarily via Type I mechanism, while ZnPc(TAP) 4 4+ or ZnPc(TAP) 4 8+ created ROS by both type I and type II mechanisms. ZnPc(TAP) 4 n+ are highly potent, rapid-acting and non-toxic photosensitizers capable of inactivating bacteria.

  1. Photosensitivity and double vision as initial symptoms of colon cancer

    DEFF Research Database (Denmark)

    Rasmussen, L. R.; Laursen, C. B.; Graumann, O.

    2015-01-01

    A 75-year-old man suffering from rheumatoid arthritis, myxoedema and type II diabetes mellitus, presented with occasional double vision and photosensitivity. The patient underwent an MRI of the brain showing a tumour located in the right of the sphenoid bone. A subsequent diagnostic CT scan of th...... of the thorax, abdomen and pelvis revealed a left-sided colon tumour, which biopsy proved as being an adenocarcinoma....

  2. Ultrafast electron injection at the cationic porphyrin-graphene interface assisted by molecular flattening

    KAUST Repository

    Aly, Shawkat Mohammede

    2014-01-01

    The steady-state and femtosecond (fs) time-resolved data clearly demonstrate that the charge transfer (CT) process at the porphyrin-graphene carboxylate (GC) interfaces can be tuned from zero to very sufficient and ultrafast by changing the electronic structure of the meso unit and the redox properties of the porphyrin cavity. This journal is © the Partner Organisations 2014.

  3. Synthesis, Characterization, and Saccharide Binding Studies of Bile Acid − Porphyrin Conjugates

    Directory of Open Access Journals (Sweden)

    Vladimír Král

    2007-01-01

    Full Text Available Synthesis and characterization of bile acid-porphyrin conjugates (BAPs are reported. Binding of saccharides with BAPs in aqueous methanol was studied by monitoring changes in the visible absorption spectral of the porphyrin-moieties. Although these studies clearly showed absorbance changes, suggesting quite high if non-selective binding, the mass spectral studies do not unambiguously support these results.

  4. To what extent can charge localization influence electron injection efficiency at graphene-porphyrin interfaces?

    KAUST Repository

    Parida, Manas R.

    2015-04-28

    Controlling the electron transfer process at donor- acceptor interfaces is a research direction that has not yet seen much progress. Here, with careful control of the charge localization on the porphyrin macrocycle using β -Cyclodextrin as an external cage, we are able to improve the electron injection efficiency from cationic porphyrin to graphene carboxylate by 120% . The detailed reaction mechanism is also discussed.

  5. Molecular modeling of cationic porphyrin-anthraquinone hybrids as DNA topoisomerase IIβ inhibitors.

    Science.gov (United States)

    Arba, Muhammad; Ruslin; Ihsan, Sunandar; Tri Wahyudi, Setyanto; Tjahjono, Daryono H

    2017-12-01

    Human DNA Topoisomerase II has been regarded as a promising target in anticancer drug discovery. In the present study, we designed six porphyrin-anthraquinone hybrids bearing pyrazole or pyridine group as meso substituents and evaluated their potentials as DNA Topoisomerase IIβ inhibitor. First, we investigated the binding orientation of porphyrin hybrids into DNA topoisomerase IIβ employing AutoDock 4.2 and then performed 20-ns molecular dynamics simulations to see the dynamic stability of each porphyrin-Topo IIβ complex using Amber 14. We found that the binding of porphyrin hybrids occured through intercalation and groove binding mode in addition interaction with the amino acid residues constituting the active cavity of Topo IIβ. Each porphyrin-Topo IIβ complex was stabilized during 20-ns dynamics simulations. The MM-PBSA free energy calculation shows that the binding affinities of porphyrin hybrids were modified with the number of meso substituent. Interestingly, the affinity of all porphyrin hybrids to Topo IIβ was stronger than that of native ligand (EVP), indicating the potential of the designed porphyrin to be considered in experimental research. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Air oxidation of the kerogen/asphaltene vanadyl porphyrins: an electron spin resonance study

    Directory of Open Access Journals (Sweden)

    MIRJANA S. PAVLOVIC

    2000-02-01

    Full Text Available The thermal behavior of vanadyl porphyrins was studied by electron spin resonance during heating of kerogens, isolated from the La Luna (Venezuela and Serpiano (Switzerland bituminous rocks, at 25°C for 1 to 20 days in the presence of air. During the thermal treatment of the kerogens, the vanadyl porphyrins resonance signals decrease monotonically and become quite small after 6 days of heating. Concomitantly, new vanadyl signals appear and, at longer heating times, dominate the spectrum. It is suggested that the secondary vanadyl species must have been formed from vanadyl porphyrins. Similar conversions of vanadyl porphyrins are observed under the same experimental conditions for asphaltenes extracted from the La Luna and Serpiano rocks, and floating asphalt from the Dead Sea (Israel. A comparison of the spin-Hamiltonian parameters for vanadyl porphyrins and the vanadyl compounds obtained during pyrolysis of the kerogens/asphaltenes suggests that the latter are of a non-porphyrin type. For comparison a study was conducted on Western Kentucky No. 9 coal enriched with vanadium (>>400 ppm from six mines. All the coal samples show only the presence of predominant by non-porphyrin vanadyl compounds, similar to those generated through laboratory heating of the kerogens/asphaltenes in air. In addition, some samples also contain a minor amount of vanadyl porphyrins.

  7. Boron steel. I Part. Preparation

    International Nuclear Information System (INIS)

    Jaraiz Franco, E.; Esteban Hernandez, J. A.

    1960-01-01

    With the advent of the first nuclear reactors arise the need for control rods and shielding duties for some types of radiations. One of the materials used for this purpose has been the high boron steel. This paper describes the melting and casting procedures employed for the production, at laboratory scale, of steels with Boron content ranging from 1 to 4 per cent, as well as the metallographic and X-Ray techniques used for the identification of the present phases. The electrolytic technique employed for the isolation of the Fe 2 B phase and its subsequent X-Ray identification has proved to be satisfactory. (Author) 11 refs

  8. Thermal conductivity of boron carbides

    Science.gov (United States)

    Wood, C.; Emin, D.; Gray, P. E.

    1985-01-01

    Knowledge of the thermal conductivity of boron carbide is necessary to evaluate its potential for high-temperature thermoelectric energy conversion applications. Measurements have been conducted of the thermal diffusivity of hot-pressed boron carbide BxC samples as a function of composition (x in the range from 4 to 9), temperature (300-1700 K), and temperature cycling. These data, in concert with density and specific-heat data, yield the thermal conductivities of these materials. The results are discussed in terms of a structural model that has been previously advanced to explain the electronic transport data. Some novel mechanisms for thermal conduction are briefly discussed.

  9. New Icosahedral Boron Carbide Semiconductors

    Science.gov (United States)

    Echeverria Mora, Elena Maria

    Novel semiconductor boron carbide films and boron carbide films doped with aromatic compounds have been investigated and characterized. Most of these semiconductors were formed by plasma enhanced chemical vapor deposition. The aromatic compound additives used, in this thesis, were pyridine (Py), aniline, and diaminobenzene (DAB). As one of the key parameters for semiconducting device functionality is the metal contact and, therefore, the chemical interactions or band bending that may occur at the metal/semiconductor interface, X-ray photoemission spectroscopy has been used to investigate the interaction of gold (Au) with these novel boron carbide-based semiconductors. Both n- and p-type films have been tested and pure boron carbide devices are compared to those containing aromatic compounds. The results show that boron carbide seems to behave differently from other semiconductors, opening a way for new analysis and approaches in device's functionality. By studying the electrical and optical properties of these films, it has been found that samples containing the aromatic compound exhibit an improvement in the electron-hole separation and charge extraction, as well as a decrease in the band gap. The hole carrier lifetimes for each sample were extracted from the capacitance-voltage, C(V), and current-voltage, I(V), curves. Additionally, devices, with boron carbide with the addition of pyridine, exhibited better collection of neutron capture generated pulses at ZERO applied bias, compared to the pure boron carbide samples. This is consistent with the longer carrier lifetimes estimated for these films. The I-V curves, as a function of external magnetic field, of the pure boron carbide films and films containing DAB demonstrate that significant room temperature negative magneto-resistance (> 100% for pure samples, and > 50% for samples containing DAB) is possible in the resulting dielectric thin films. Inclusion of DAB is not essential for significant negative magneto

  10. Chemical separation of boron isotopes

    International Nuclear Information System (INIS)

    Palko, A.A.

    1978-06-01

    This is the final report of the research performed at ORNL on the chemical fractionation of boron isotopes between BF 3 gas and the liquid molecular addition compounds of BF 3 . Thirty compounds were studied, ten of them in detail. Graphs and equations are given for variation of isotopic equilibrium constant, vapor pressure, and BF 3 solubility as a function of temperature. Rate of isotopic exchange and melting points were determined. Several of the compounds are likely candidates for use in a gas-liquid countercurrent exchange system for large-scale separation of boron isotopes. 23 figs, 53 tables, 39 references

  11. Chemical separation of boron isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Palko, A.A.

    1978-06-01

    This is the final report of the research performed at ORNL on the chemical fractionation of boron isotopes between BF/sub 3/ gas and the liquid molecular addition compounds of BF/sub 3/. Thirty compounds were studied, ten of them in detail. Graphs and equations are given for variation of isotopic equilibrium constant, vapor pressure, and BF/sub 3/ solubility as a function of temperature. Rate of isotopic exchange and melting points were determined. Several of the compounds are likely candidates for use in a gas-liquid countercurrent exchange system for large-scale separation of boron isotopes. 23 figs, 53 tables, 39 references.

  12. Boron cycling in subduction zones

    OpenAIRE

    Palmer, Martin R.

    2017-01-01

    Subduction zones are geologically dramatic features, with much of the drama being driven by the movement of water. The “light and lively” nature of boron, coupled with its wide variations in isotopic composition shown by the different geo-players in this drama, make it an ideal tracer for the role and movement of water during subduction. The utility of boron ranges from monitoring how the fluids that are expelled from the accretionary prism influence seawater chemistry, to the subduction of c...

  13. Photopatch and UV-irradiated patch testing in photosensitive dermatitis

    Directory of Open Access Journals (Sweden)

    Reena Rai

    2016-01-01

    Full Text Available Background: The photopatch test is used to detect photoallergic reactions to various antigens such as sunscreens and drugs. Photosensitive dermatitis can be caused due to antigens like parthenium, fragrances, rubbers and metals. The photopatch test does not contain these antigens. Therefore, the Indian Standard Series (ISS along with the Standard photopatch series from Chemotechnique Diagnostics, Sweden was used to detect light induced antigens. Aim: To detect light induced antigens in patients with photosensitive dermatitis. Methods: This study was done in a descriptive, observer blinded manner. Photopatch test and ISS were applied in duplicate on the patient's back by the standard method. After 24 hours, readings were recorded according to ICDRG criteria. One side was closed and other side irradiated with 14 J/cm2 of UVA and a second set of readings were recorded after 48 hrs. Result: The highest positivity was obtained with parthenium, with 18 out of 35 (51% patients showing a positive patch test reaction with both photoallergic contact dermatitis and photoaggravation. Four patients (11% showed positive patch test reaction suggestive of contact dermatitis to potassium dichromate and fragrance mix. Six patients had contact dermatitis to numerous antigens such as nickel, cobalt, chinoform and para-phenylenediamine. None of these patients showed photoaggravation on patch testing. Conclusion: Parthenium was found to cause photoallergy, contact dermatitis with photoaggravation and contact allergy. Hence, photopatch test and UV irradiated patch test can be an important tool to detect light induced antigens in patients with photosensitive dermatitis.

  14. Singlet Oxygen Detection Using Red Wine Extracts as Photosensitizers.

    Science.gov (United States)

    Lagunes, Irene; Vázquez-Ortega, Fernanda; Trigos, Ángel

    2017-09-01

    Moderate consumption of red wine provides beneficial effects to health. This is attributed to polyphenol compounds present in wine such as resveratrol, quercetin, gallic acid, rutin, and vanillic acid. The amount of these antioxidants is variable; nevertheless, the main beneficial effects of red wine are attributed to resveratrol. However, it has been found that resveratrol and quercetin are able to photosensitize singlet oxygen generation and conversely, gallic acid acts as quencher. Therefore, and since resveratrol and quercetin are some of the most important antioxidants reported in red wines, the aim of this research was to evaluate the photosensitizing ability of 12 red wine extracts through photo-oxidation of ergosterol. The presence of 1 O 2 was detected by ergosterol conversion into peroxide of ergosterol through 1 H NMR analysis. Our results showed that 10 wine extracts were able to act as photosensitizers in the generation of singlet oxygen. The presence of 1 O 2 can damage other compounds of red wine and cause possible organoleptic alterations. Finally, although the reaction conditions employed in this research do not resemble the inherent conditions in wine making processing or storing, or even during its consumption, this knowledge could be useful to prevent possible pro-oxidant effects and avoid detrimental effects in red wines. © 2017 Institute of Food Technologists®.

  15. The (6-4) Dimeric Lesion as a DNA Photosensitizer.

    Science.gov (United States)

    Vendrell-Criado, Victoria; Rodríguez-Muñiz, Gemma M; Lhiaubet-Vallet, Virginie; Cuquerella, M Consuelo; Miranda, Miguel A

    2016-07-04

    Based on our previous investigations into the photophysical properties of the 5-methyl-2-pyrimidone (Pyo) chromophore, we now extend our studies to the photobehavior of the dimeric (6-4) thymine photoproducts (6-4 PP) to evaluate their capability to act as instrinsic DNA photosensitizers. The lesion presents significant absorption in the UVB/UVA region, weak fluorescence emission, a singlet-excited-state energy of approximately 351 kJ mol(-1) , and a triplet-excited-state energy of 297 kJ mol(-1) . Its triplet transient absorption has a maximum at 420-440 nm, a lifetime of around 7 μs, and a high formation quantum yield, ΦISC =0.86. This species is efficiently quenched by thymidine. Its DNA photosensitizing properties are demonstrated by a series of experiments run on a pBR322 plasmid. The lesion photoinduces both single-strand breaks and the formation of cyclobutane thymine dimers. Altogether, these results show that, the substitution of the pyrimidone ring at C4 by a 5-hydroxy-5,6-dihydrothymine does not cancel out the photosensitization properties of the chromophore. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Photosensitizer-gold nanorod composite for targeted multimodal therapy.

    Science.gov (United States)

    Wang, Jian; You, Mingxu; Zhu, Guizhi; Shukoor, Mohammed Ibrahim; Chen, Zhuo; Zhao, Zilong; Altman, Meghan B; Yuan, Quan; Zhu, Zhi; Chen, Yan; Huang, Cheng Zhi; Tan, Weihong

    2013-11-11

    In this work, a DNA inter-strand replacement strategy for therapeutic activity is successfully designed for multimodal therapy. In this multimodal therapy, chlorin e6 (Ce6) photosensitizer molecules are used for photodynamic therapy (PDT), while aptamer-AuNRs, are used for selective binding to target cancer cells and for photothermal therapy (PTT) with near infrared laser irradiation. Aptamer Sgc8, which specifically targets leukemia T cells, is conjugated to an AuNR by a thiol-Au covalent bond and then hybridized with a Ce6-labeled photosensitizer/reporter to form a DNA double helix. When target cancer cells are absent, Ce6 is quenched and shows no PDT effect. However, when target cancer cells are present, the aptamer changes structure to release Ce6 to produce singlet oxygen for PDT upon light irradiation. Importantly, by combining photosensitizer and photothermal agents, PTT/PDT dual therapy supplies a more effective therapeutic outcome than either therapeutic modality alone. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Photosensitized inactivation of infectious blood-borne human parasites

    Science.gov (United States)

    Judy, Millard M.; Sogandares-Bernal, Franklin M.; Matthews, James Lester

    1995-05-01

    Blood-borne viruses and protozoan parasites that are infectious to humans pose risk world-wide of infection transmission through blood and blood product transfusion. Blood-borne infectious viruses include human immunodeficiency virus (HIV-I), which causes AIDS; hepatitis C virus, which can cause chronic hepatitis; and cytomegalovirus, which can be dangerous to immunocompromised patients, e.g., the newborn, transplant recipients, and AIDS patients. Infectious blood-borne protozoan parasites include Trypanosoma cruzi, which causes Chagas' disease, endemic throughout Central and South America; the Trypanosoma species causing African sleeping sickness endemic in Central Africa; and Plasmodium falciparum, which causes malignant and increasingly drug- resistant human malaria prevalent throughout the tropics. Some researchers have focused on using photosensitizers to inactivate HIV-I and other viruses in whole blood, packed red cells, and platelet concentrates without compromising blood product function. Our group previously has reported photosensitized in vitro inactivation of P. falciparum and the mouse malaria organism Plasmodium berghei in whole blood using hematoporphyrin derivative (HPD) and of T. cruzi using benzoporphyrin derivatives BPDMA and BPDDA, dihematoporphyrin ether (DHE), and hydroxyethylvinyldeuteroporphyrin (HEVD). These results suggest that continued investigation is warranted to evaluate the potential for photosensitized inactivation of blood-borne parasites in blood banking.

  18. Formation and thermodynamic stability of (polymer + porphyrin) supramolecular structures in aqueous solutions

    International Nuclear Information System (INIS)

    Costa, Viviana C.P. da; Hwang, Barrington J.; Eggen, Spencer E.; Wallace, Megan J.; Annunziata, Onofrio

    2014-01-01

    Highlights: • Thermodynamic stability of a (polymer + porphyrin) supramolecular structure was characterized. • Isothermal titration calorimetry provided two ways to determine reaction enthalpies. • Exothermic (polymer + porphyrin) binding competes with porphyrin self-association. • (Polymer + porphyrin) binding is entropically favored with respect to porphyrin self-association. • Spectral shifts show importance of porphyrin central hydrogens in polymer binding. - Abstract: Optical properties of porphyrins can be tuned through (polymer + porphyrin) (host + guest) binding in solution. This gives rise to the formation of supramolecular structures. In this paper, the formation, thermodynamic stability and spectroscopic properties of (polymer + porphyrin) supramolecular structures and their competition with porphyrin self-association were investigated by both isothermal titration calorimetry (ITC) and absorption spectroscopy. Specifically, reaction enthalpies and equilibrium constants were measured for meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS) self-association and TPPS binding to the polymer poly(vinylpyrrolidone) (PVP, 40 kg/mol) in aqueous solutions at pH 7 and three different temperatures (12, 25 and 37 °C). ITC, compared to spectroscopic techniques, provides two independent means to determine reaction enthalpies: direct measurements and Van’t Hoff plot. This was used as a criterion to assess that (1) self-association of TPPS is limited to the formation of dimers and (2) TPPS binds to PVP in its monomeric state only. The formation of TPPS dimers and (PVP + TPPS) supramolecular structures are both enthalpically driven. However, (polymer + porphyrin) binding was found to be entropically favored compared to dimerization. Furthermore, the reaction enthalpies of these two processes significantly depend on temperature. This behavior was attributed to hydrophobic interactions. Finally, the limiting absorption spectra of monomeric, dimeric and polymer

  19. Boron Nitride Nanoribbons from Exfoliation of Boron Nitride Nanotubes

    Science.gov (United States)

    Hung, Ching-Cheh; Hurst, Janet; Santiago, Diana

    2017-01-01

    Two types of boron nitride nanotubes (BNNTs) were exfoliated into boron nitride nanoribbons (BNNR), which were identified using transmission electron microscopy: (1) commercial BNNTs with thin tube walls and small diameters. Tube unzipping was indicated by a large decrease of the sample's surface area and volume for pores less than 2 nm in diameter. (2) BNNTs with large diameters and thick walls synthesized at NASA Glenn Research Center. Here, tube unraveling was indicated by a large increase in external surface area and pore volume. For both, the exfoliation process was similar to the previous reported method to exfoliate commercial hexagonal boron nitride (hBN): Mixtures of BNNT, FeCl3, and NaF (or KF) were sequentially treated in 250 to 350 C nitrogen for intercalation, 500 to 750 C air for exfoliation, and finally HCl for purification. Property changes of the nanosized boron nitride throughout this process were also similar to the previously observed changes of commercial hBN during the exfoliation process: Both crystal structure (x-ray diffraction data) and chemical properties (Fourier-transform infrared spectroscopy data) of the original reactant changed after intercalation and exfoliation, but most (not all) of these changes revert back to those of the reactant once the final, purified products are obtained.

  20. Synthesis of boron nitride from boron containing poly (vinyl alcohol ...

    Indian Academy of Sciences (India)

    A ceramic precursor, prepared by condensation reaction from poly(vinyl alcohol) (PVA) and boric acid (H3BO3) in 1:1, 2:1 and 4:1 molar ratios, was synthesized as low temperature synthesis route for boron nitride ceramic. Samples were pyrolyzed at 850°C in nitrogen atmosphere followed by characterization using Fourier ...

  1. Peroxynitrite formation in nitric oxide-exposed submitochondrial particles: detection, oxidative damage and catalytic removal by Mn-porphyrins.

    Science.gov (United States)

    Valez, Valeria; Cassina, Adriana; Batinic-Haberle, Ines; Kalyanaraman, Balaraman; Ferrer-Sueta, Gerardo; Radi, Rafael

    2013-01-01

    Peroxynitrite (ONOO(-)) formation in mitochondria may be favored due to the constant supply of superoxide radical (O(2)(∙-)) by the electron transport chain plus the facile diffusion of nitric oxide ((∙)NO) to this organelle. Herein, a model system of submitochondrial particles (SMP) in the presence of succinate plus the respiratory inhibitor antimycin A (to increase O(2)(∙-) rates) and the (∙)NO-donor NOC-7 was studied to directly establish and quantitate peroxynitrite by a multiplicity of methods including chemiluminescence, fluorescence and immunochemical analysis. While all the tested probes revealed peroxynitrite at near stoichiometric levels with respect to its precursor radicals, coumarin boronic acid (a probe that directly reacts with peroxynitrite) had the more straightforward oxidation profile from O(2)(∙-)-forming SMP as a function of the (∙)NO flux. Interestingly, immunospintrapping studies verified protein radical generation in SMP by peroxynitrite. Substrate-supplemented SMP also reduced Mn(III)porphyrins (MnP) to Mn(II)P under physiologically-relevant oxygen levels (3-30 μM); then, Mn(II)P were capable to reduce peroxynitrite and protect SMP from the inhibition of complex I-dependent oxygen consumption and protein radical formation and nitration of membranes. The data directly support the formation of peroxynitrite in mitochondria and demonstrate that MnP can undergo a catalytic redox cycle to neutralize peroxynitrite-dependent mitochondrial oxidative damage. Copyright © 2012 Elsevier Inc. All rights reserved.

  2. High density intercalation of porphyrin into transparent clay membrane without aggregation.

    Science.gov (United States)

    Fujimura, Takuya; Shimada, Tetsuya; Hamatani, Satoshi; Onodera, Shingo; Sasai, Ryo; Inoue, Haruo; Takagi, Shinsuke

    2013-04-23

    Cationic porphyrin was successfully intercalated into transparent clay membrane by developing the new strategy for the sample preparation conditions. When water:ethanol = 1:2 (v:v) was used as solvent for porphyrin penetration process, high density intercalation of porphyrin into the clay membrane was achieved. In the interlayer space, porphyrin molecules do not aggregate owing to intercharge distance matching effect (size-matching effect), even at high density condition. Judging from XRD and absorption measurements, the orientations of the porphyrins in the clay layers should be almost parallel to the clay nanosheet as monolayer. Because the fluorescence quantum yield did not depend on its loading level, it is turned out that intercalated TMPyP in the clay film keeps the photoactivity even under the high density conditions.

  3. Two novel self-assemblies of supramolecular solar cells using N-heterocyclic-anchoring porphyrins

    Science.gov (United States)

    Zhang, Qian; Wu, Fang-Yuan; Liu, Jia-Cheng; Li, Ren-Zhi; Jin, Neng-Zhi

    2018-02-01

    Two novel N-substituted anchoring porphyrins (ZnPAtz and ZnPAim) have been devised and synthesized. Moreover, these two anchoring porphyrins were linked to the TiO2 semiconductor through carboxyl groups and then a zinc porphyrin ZnP was bound to the anchoring porphyrin using a zinc-to-ligand axial coordination approach. The different performances of these assemblies were compared with single anchoring porphyrin devices ZnPAtz and ZnPAim. The photoelectric conversion efficiency of the new supramolecular solar cells sensitized by ZnP-ZnPAx (x = tz, im) has been improved. The ZnP-ZnPAtz-based DSSCs provided the highest photovoltaic efficiency (1.86%). Fundamental studies showed that incorporation of these assemblies promote light-harvesting efficiency.

  4. Boron analysis and boron imaging in biological materials for Boron Neutron Capture Therapy (BNCT).

    Science.gov (United States)

    Wittig, Andrea; Michel, Jean; Moss, Raymond L; Stecher-Rasmussen, Finn; Arlinghaus, Heinrich F; Bendel, Peter; Mauri, Pier Luigi; Altieri, Saverio; Hilger, Ralf; Salvadori, Piero A; Menichetti, Luca; Zamenhof, Robert; Sauerwein, Wolfgang A G

    2008-10-01

    Boron Neutron Capture Therapy (BNCT) is based on the ability of the stable isotope 10B to capture neutrons, which leads to a nuclear reaction producing an alpha- and a 7Li-particle, both having a high biological effectiveness and a very short range in tissue, being limited to approximately one cell diameter. This opens the possibility for a highly selective cancer therapy. BNCT strongly depends on the selective uptake of 10B in tumor cells and on its distribution inside the cells. The chemical properties of boron and the need to discriminate different isotopes make the investigation of the concentration and distribution of 10B a challenging task. The most advanced techniques to measure and image boron are described, both invasive and non-invasive. The most promising approach for further investigation will be the complementary use of the different techniques to obtain the information that is mandatory for the future of this innovative treatment modality.

  5. Boron-enhanced diffusion of boron from ultralow-energy boron implantation

    International Nuclear Information System (INIS)

    Agarwal, A.; Eaglesham, D.J.; Gossmann, H.J.; Pelaz, L.; Herner, S.B.; Jacobson, D.C.

    1998-01-01

    The authors have investigated the diffusion enhancement mechanism of BED (boron enhanced diffusion), wherein the boron diffusivity is enhanced three to four times over the equilibrium diffusivity at 1,050 C in the proximity of a silicon layer containing a high boron concentration. It is shown that BED is associated with the formation of a fine-grain polycrystalline silicon boride phase within an initially amorphous Si layer having a high B concentration. For 0.5 keV B + , the threshold implantation dose which leads to BED lies between 3 x 10 14 and of 1 x 10 15 /cm -2 . Formation of the shallowest possible junctions by 0.5 keV B + requires that the implant dose be kept lower than this threshold

  6. Analytical boron diffusivity model in silicon for thermal diffusion from boron silicate glass film

    Science.gov (United States)

    Kurachi, Ikuo; Yoshioka, Kentaro

    2015-09-01

    An analytical boron diffusivity model in silicon for thermal diffusion from a boron silicate glass (BSG) film has been proposed in terms of enhanced diffusion due to boron-silicon interstitial pair formation. The silicon interstitial generation is considered to be a result of the silicon kick-out mechanism by the diffused boron at the surface. The additional silicon interstitial generation in the bulk silicon is considered to be the dissociation of the diffused pairs. The former one causes the surface boron concentration dependent diffusion. The latter one causes the local boron concentration dependent diffusion. The calculated boron profiles based on the diffusivity model are confirmed to agree with the actual diffusion profiles measured by secondary ion mass spectroscopy (SIMS) for a wide range of the BSG boron concentration. This analytical diffusivity model is a helpful tool for p+ boron diffusion process optimization of n-type solar cell manufacturing.

  7. Boron removal from wastewater using adsorbents.

    Science.gov (United States)

    Kluczka, J; Trojanowska, J; Zolotajkin, M; Ciba, J; Turek, M; Dydo, P

    2007-01-01

    In the present study, boron adsorption on activated alumina and activated carbon impregnated with calcium chloride, tartaric acid and mannitol was investigated. The adsorbate in question was the wastewater from the chemical landfill in Tarnowskie Gory of 25-70 mg l(-1) boron content. The removal of boron from the above-described wastewater was examined in the static (batch) and dynamic (column) experiments. The static experiments were carried out to assess boron adsorption isotherms, based on which the most efficient adsorbent as well as the rough resin load was determined. On the basis of the dynamic experiment results, the boron adsorptive capacities of the examined resins were deduced. It was concluded that the use of the impregnants increased the ability of activated carbon to adsorb boron. Granulated activated carbon WG-12 impregnated with mannitol was found to be the most promising for the boron removal from wastewater of the Chemical Wastewater Plant in Tarnowskie Gory.

  8. The spectroscopic impact of interactions with the four Gouterman orbitals from peripheral decoration of porphyrins with simple electron withdrawing and donating groups.

    Science.gov (United States)

    Zhang, Angel; Kwan, Lydia; Stillman, Martin J

    2017-11-07

    Tetrapyrroles are of great interest for solar cell and photodynamic therapy applications due to their structural analogy with chlorophyll, a natural photosensitizer. Unsubstituted symmetric porphyrins exhibit weak absorption in the red region which makes them unsuitable for these applications. The push-pull peripheral decoration modifies the energies of the frontier molecular orbitals, which in turn influences the tetrapyrrole's spectroscopic properties. The absorption, magnetic circular dichroism, and emission spectra were measured for four zinc tetratolylporphyrin compounds substituted peripherally with a fused dimethoxybenzo group as an electron withdrawing group (EWG) on one pyrrole and on the opposite pyrrole, a single acetamido (1), a nitro (2), a proton (3), or a benzoylamino (4) substituent. Unusually, the magnetic circular dichroism spectrum of 2 exhibited a negative A term for the lowest energy absorption band (the Q band) and its emission spectrum was also unlike those of 1, 3, and 4. A complete computational analysis was carried out to obtain the energies and electron distribution, shown by electron density surfaces, of the four Gouterman MOs. TD-DFT calculations showed that for 2, ΔLUMO was greater than ΔHOMO, which accounted for the observed negative A term. The trend in the estimated MCD A term magnitudes, normalized to the absorbance as [A/(dipole strength) BM], provides experimental confirmation of the computationally determined ratio of ΔLUMO/ΔHOMO data. The value of ΔHOMO was confirmed by the trend in oscillator strengths. A series of fictive porphyrins (F1-F5) incorporating simple push-pull substituents were designed and their electronic structures were investigated using TD-DFT calculations. The substituents in the five fictive molecules illustrate the differential effect of the donor and acceptor groups in the β-position of the pyrroles on the relative stabilities of the four Gouterman orbitals. NO 2 groups result in the greatest

  9. In vivo photoacoustic monitoring of photosensitizer in skin: application to dosimetry for antibacterial photodynamic treatment

    Science.gov (United States)

    Hirao, Akihiro; Sato, Shunichi; Saitoh, Daizoh; Shinomiya, Nariyoshi; Ashida, Hiroshi; Obara, Minoru

    2009-02-01

    To obtain efficient antibacterial photodynamic effect in traumatic injuries such as burns, depth-resolved dosimetry of photosensitizer is required. In this study, we performed dual-wavelength photoacoustic (PA) measurement for rat burned skins injected with a photosensitizer. As a photosensitizer, methylene blue (MB) or porfimer sodium was injected into the subcutaneous tissue in rats with deep dermal burn. The wound was irradiated with red (665 nm or 630 nm) pulsed light to excite photosensitizers and green (532 nm) pulsed light to excite blood in the tissue; the latter signal was used to eliminate blood-associated component involved in the former signal. Acoustic attenuation was also compensated from the photosensitizer-associated PA signals. These signal processing was effective to obtain high-contrast image of a photosensitizer in the tissue. Behaviors of MB and porfimer sodium in the tissue were compared.

  10. CHD2 variants are a risk factor for photosensitivity in epilepsy

    DEFF Research Database (Denmark)

    Galizia, Elizabeth C.; Myers, Candace T.; Leu, Costin

    2015-01-01

    encephalopathies due to other gene mutations. We determined whether CHD2 variation underlies photosensitivity in common epilepsies, specific photosensitive epilepsies and individuals with photosensitivity without seizures. We studied 580 individuals with epilepsy and either photosensitive seizures or abnormal......-represented in cases overall (P = 2.17 × 10(-5)). Among epilepsy syndromes, there was over-representation of unique CHD2 variants (3/36 cases) in the archetypal photosensitive epilepsy syndrome, eyelid myoclonia with absences (P = 3.50 × 10(-4)). CHD2 variation was not over-represented in photoparoxysmal response...... with absences. Unique CHD2 variants are also associated with photosensitivity in common epilepsies. CHD2 does not encode an ion channel, opening new avenues for research into human cortical excitability....

  11. Advanced microstructure of boron carbide.

    Science.gov (United States)

    Werheit, Helmut; Shalamberidze, Sulkhan

    2012-09-26

    The rhombohedral elementary cell of the complex boron carbide structure is composed of B(12) or B(11)C icosahedra and CBC, CBB or B□B (□, vacancy) linear arrangements, whose shares vary depending on the actual chemical compound. The evaluation of the IR phonon spectra of isotopically pure boron carbide yields the quantitative concentrations of these components within the homogeneity range. The structure formula of B(4.3)C at the carbon-rich limit of the homogeneity range is (B(11)C) (CBC)(0.91) (B□B)(0.09) (□, vacancy); and the actual structure formula of B(13)C(2) is (B(12))(0.5)(B(11)C)(0.5)(CBC)(0.65)(CBB)(0.16) (B□B)(0.19), and deviates fundamentally from (B(12))CBC, predicted by theory to be the energetically most favourable structure of boron carbide. In reality, it is the most distorted structure in the homogeneity range. The spectra of (nat)B(x)C make it evident that boron isotopes are not randomly distributed in the structure. However, doping with 2% silicon brings about a random distribution.

  12. Boron isotopes in geothermal systems

    International Nuclear Information System (INIS)

    Aggarwal, J.

    1997-01-01

    Boron is a highly mobile element and during water-rock reactions, boron is leached out of rocks with no apparent fractionation. In geothermal systems where the water recharging the systems are meteoric in origin, the B isotope ratio of the geothermal fluid reflects the B isotope ratio of the rocks. Seawater has a distinctive B isotope ratio and where seawater recharges the geothermal system, the B isotope ratio of the geothermal system reflects the mixing of rock derived B and seawater derived B. Any deviations of the actual B isotope ratio of a mixture reflects subtle differences in the water-rock ratios in the cold downwelling limb of the hydrothermal system. This paper will present data from a variety of different geothermal systems, including New Zealand; Iceland; Yellowston, USA; Ibusuki, Japan to show the range in B isotope ratios in active geothermal systems. Some of these systems show well defined mixing trends between seawater and the host rocks, whilst others show the boron isotope ratios of the host rock only. In geothermal systems containing high amounts of CO 2 boron isotope ratios from a volatile B source can also be inferred. (auth)

  13. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    electrolysis was crystalline in nature, X-ray diffraction pat-. ∗. Author for correspondence (sas@igcar.gov.in) .... Elemental boron was synthesized by the electrolysis of molten potassium fluroborate dissolved in a ... A high-throughput Renishaw micro-Raman spectrome- ter (model Invia) was employed to record Raman ...

  14. Preparation process of boron nitride

    International Nuclear Information System (INIS)

    Mignani, G.; Ardaud, P.

    1990-01-01

    High purity boron nitride, without Si and a low carbon content, is prepared by pyrolysis, under an ammoniac atmosphere, of the reaction product between a B-trihalogenoborazole and a primary amine RNH 2 when R is a hydrocarbon radical eventually substituted containing from 1 to 6 carbon atoms inclusively [fr

  15. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    Structural characterization of electrodeposited boron was carried out by using transmission electron microscopy and Raman spectroscopy. Electron diffraction and phase contrast imaging were carried out by using transmission electron microscopy. Phase identification was done based on the analysis of electron diffraction ...

  16. Method of separating boron isotopes

    Science.gov (United States)

    Jensen, Reed J.; Thorne, James M.; Cluff, Coran L.; Hayes, John K.

    1984-01-01

    A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)dichloroborane as the feed material. The photolysis can readily be achieved with CO.sub.2 laser radiation and using fluences significantly below those required to dissociate BCl.sub.3.

  17. Prevention of uncontrolled boron dilution

    International Nuclear Information System (INIS)

    Sere, J. L.

    1997-01-01

    The paper presents a synthesis of the global analysis of uncontrolled boron dilution risk performed by (European Consortium Mochovce (EUCOM) in the frame of Safety Measures RC 01 and AA 11. Recommendation for additional improvements (mainly I and C interlocks or inhibition) are presented. (author)

  18. Boron-11 MRI and MRS of intact animals infused with a boron neutron capture agent

    International Nuclear Information System (INIS)

    Kabalka, G.W.; Davis, M.; Bendel, P.

    1988-01-01

    Boron neutron capture therapy (BNCT) depends on the delivery of boron-containing drugs to a targeted lesion. Currently, the verification and quantification of in vivo boron content is a difficult problem. Boron-11 spectroscopy was utilized to confirm the presence of a dimeric sulfhydryl dodecaborane BNCT agent contained in an intact animal. Spectroscopy experiments revealed that the decay time of transverse magnetization of the boron-11 spins was less than 1 ms which precluded the use of a 2DFT imaging protocol. A back-projection protocol was developed and utilized to generate the first boron-11 image of a BNCT agent in the liver of an intact Fisher 344 rat

  19. Non-invasive Photodynamic Therapy in Brain Cancer by Use of Tb3+-Doped LaF3 Nanoparticles in Combination with Photosensitizer Through X-ray Irradiation: A Proof-of-Concept Study

    Science.gov (United States)

    Chen, Min-Hua; Jenh, Yi-Jhen; Wu, Sheng-Kai; Chen, Yo-Shen; Hanagata, Nobutaka; Lin, Feng-Huei

    2017-01-01

    The use of photodynamic therapy (PDT) in the treatment of brain cancer has produced exciting results in clinical trials over the past decade. PDT is based on the concept that a photosensitizer exposed to a specific light wavelength produces the predominant cytotoxic agent, to destroy tumor cells. However, delivering an efficient light source to the brain tumor site is still a challenge. The light source should be delivered by placing external optical fibers into the brain at the time of surgical debulking of the tumor. Consequently, there exists the need for a minimally invasive treatment for brain cancer PDT. In this study, we investigated an attractive non-invasive option on glioma cell line by using Tb3+-doped LaF3 scintillating nanoparticles (LaF3:Tb) in combination with photosensitizer, meso-tetra(4-carboxyphenyl)porphyrin (MTCP), followed by activation with soft X-ray (80 kVp). Scintillating LaF3:Tb nanoparticles, with sizes of approximately 25 nm, were fabricated. The particles have a good dispersibility in aqueous solution and possess high biocompatibility. However, significant cytotoxicity was observed in the glioma cells while the LaF3:Tb nanoparticles with MTCP were exposed under X-ray irradiation. The study has demonstrated a proof of concept as a non-invasive way to treat brain cancer in the future.

  20. Fluorescent proteins as singlet oxygen photosensitizers: mechanistic studies in photodynamic inactivation of bacteria

    Science.gov (United States)

    Ruiz-González, Rubén.; White, John H.; Cortajarena, Aitziber L.; Agut, Montserrat; Nonell, Santi; Flors, Cristina

    2013-02-01

    Antimicrobial photodynamic therapy (aPDT) combines a photosensitizer, light and oxygen to produce reactive oxygen species (ROS), mainly singlet oxygen (1O2), to photo-oxidize important biomolecules and induce cell death. aPDT is a promising alternative to standard antimicrobial strategies, but its mechanisms of action are not well understood. One of the reasons for that is the lack of control of the photosensitizing drugs location. Here we report the use of geneticallyencoded fluorescent proteins that are also 1O2 photosensitizers to address the latter issue. First, we have chosen the red fluorescent protein TagRFP as a photosensitizer, which unlike other fluorescent proteins such as KillerRed, is able to produce 1O2 but not other ROS. TagRFP photosensitizes 1O2 with a small, but not negligible, quantum yield. In addition, we have used miniSOG, a more efficient 1O2 photosensitizing fluorescent flavoprotein that has been recently engineered from phototropin 2. We have genetically incorporated these two photosensitizers into the cytosol of E. coli and demonstrated that intracellular 1O2 is sufficient to kill bacteria. Additional assays have provided further insight into the mechanism of cell death. Photodamage seems to occur primarily in the inner membrane, and extends to the outer membrane if the photosensitizer's efficiency is high enough. These observations are markedly different to those reported for external photosensitizers, suggesting that the site where 1O2 is primarily generated proves crucial for inflicting different types of cell damage.

  1. Magnetic Circular Dichroism of Porphyrin Lanthanide M3+ Complexes

    Czech Academy of Sciences Publication Activity Database

    Andrushchenko, Valery; Padula, Daniele; Zhivotova, E.; Yamamoto, S.; Bouř, Petr

    2014-01-01

    Roč. 26, č. 10 (2014), s. 655-662 ISSN 0899-0042 R&D Projects: GA ČR GA13-03978S; GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:GA AV ČR(CZ) M200550902 Institutional support: RVO:61388963 Keywords : magnetic circular dichroism * lanthanides * porphyrin complexes * density functional theory * sum over state computations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.886, year: 2014

  2. Effects of boron-water on cattle

    Energy Technology Data Exchange (ETDEWEB)

    Green, G.H.; Weeth, H.J.

    1975-01-01

    To determine the effects of subtoxic concentrations of boron in drinking water, 12 Hereford heifers were used in a 3 x 3 latin-square experiment with four squares. Treatments were tap-water (0.8 ppm boron), 150 ppm boron-water, and 300 ppm boron-water. Periods were 30 days each. Total urine was collected during the last week of each period, and renal clearance observations (based on creatinine) were made on the last day of each period. While water consumption and total urine weight were not affected by the boron treatments, hay consumption decreased, and weight loss was noted. Plasma boron concentrations were 0.53 +/- 0.151 ppm, 11.2 +/- 0.91 ppm, and 18.9 +/- 0.60 ppm while the heifers were drinking tap-water, 150 ppm boron-water, and 300 ppm boron-water respectively. Urinary boron excretion rates were tap water, 64 +/- 5.6 mg/day; 150 ppm, 2841 +/- 181.2 mg/day; 300 ppm, 4932 +/- 173.3 mg/day. Although glomerular filtration and osmolal clearance were unaffected by the boron-waters, a relative diuresis was indicated by the free water clearance effects. The percent of filtered boron which was reabsorbed decreased with increased exogenous boron, as well as both plasma and urinary phosphate. These data indicate that 300 ppm boron is not acutely toxic to heifers when consumed via the drinking water. The safe tolerance concentration, however, must lie below 150 ppm because this concentration was responsible for some deleterious effects.

  3. Photodynamic antimicrobial chemotherapy with the novel amino acid-porphyrin conjugate 4I: In vitro and in vivo studies.

    Directory of Open Access Journals (Sweden)

    Yao Yuan

    Full Text Available Photodynamic antimicrobial chemotherapy (PACT, as a novel and effective therapeutic modality to eradicate drug resistant bacteria without provoking multidrug resistance, has attracted increasing attention. This study examined the antimicrobial efficacy of the novel cationic amino acid-porphyrin conjugate 4I with four lysine groups against two different clinical isolated strains (drug sensitive and multidrug resistant of the Acinetobacter baumannii species and its toxicity on murine dermal fibroblasts in vitro, as well as the therapeutic effect of PACT on acute, potentially lethal multidrug resistant strain excisional wound infections in vivo. The PACT protocol exposed 4I to illumination, exhibiting high antimicrobial efficacy on two different strains due to a high yield of reactive oxygen species (ROS and non-selectivity to microorganisms. The photoinactivation effects of 4I against two different strains were dose-dependent. At 3.9 μM and 7.8 μM, PACT induced 6 log units of inactivation of sensitive and multidrug resistant strains. In contrast, 4I alone and illumination alone treatments had no visibly antimicrobial effect. Moreover, cytotoxicity tests revealed the great safety of the photosensitizer 4I in mice. In the in vivo study, we found 4I-mediated PACT was not only able to kill bacteria but also accelerated wound recovery. Compared with non-treated mice, over 2.89 log reduction of multidrug resistant Acinetobacter baumannii strain was reached in PACT treat mice at 24 h post-treatment. These results imply that 4I-mediated PACT therapy is an effective and safe alternative to conventional antibiotic therapy and has clinical potential for superficial drug-resistant bacterial infections.

  4. The synthesis of chlorophyll-a biosynthetic precursors and methyl substituted iron porphyrins

    International Nuclear Information System (INIS)

    Matera, K.M.

    1988-01-01

    The biosynthetic intermediates were incubated in a plant system. The activity levels calculated show that magnesium 6-acrylate porphyrins and one of the magnesium 6-β-hydroxypropionate porphyrins are not intermediates. In addition, plant systems incubated with 18 O 2 were found to synthesize magnesium 2,4-divinyl pheoporphyrin-a 5 incorporated with 18 O at the 9-carbonyl oxygen. Mass spectroscopy confirmed the presence of the oxygen label, thus eliminating one of two hypothesized pathways to chlorophyll-a. An overall description is given of iron porphyrins and iron porphyrin containing proteins. The function of the propionic side chains of the heme prosthetic group during electron transport reactions will be investigated. The synthesis of a series of iron(III) hexamethyl porphyrins with increasingly longer substituents in the remaining two peripheral positions of the porphyrin is described. Models for NMR studies of iron chlorin containing enzymes are discussed. Iron(III) pyropheophorbide-a and methyl pyropheophorbide-a were synthesized in addition to 5-CD 3 , 10-CD 2 iron(III) pyropheophorbide-a and methyl pyropheophorbide-a. Together, these pyropheophorbides were used to assign NMR resonances and ultimately provide a model for other iron chlorins. The synthesis of nickel(II) anhydro-mesorhodoporphyrin from zinc(III) anhydromesorhodochlorin is described; this nickel porphyrin was used as a standard for ring current calculations of reduced nickel analogs of anhydromesorhodoporphyrin

  5. Re-sintered boron-rich polycrystalline cubic boron nitride and method for making same

    Energy Technology Data Exchange (ETDEWEB)

    Lavens, T.R.; Corrigan, F.R.; Shott, R.L.; Bovenkerk, H.P.

    1987-06-16

    A method is described for making re-sintered polycrystalline cubic boron nitride (CBN) which comprises: (a) placing sintered substantially catalyst-free boron-rich polycrystalline cubic boron nitride particles in a high pressure/high temperature apparatus, the particles being substantially free of sintering inhibiting impurities; (b) subjecting the boron-rich cubic boron nitride particles to a pressure and a temperature adequate to re-sinter the particles, the temperature being below the CBN reconversion temperature; (c) maintaining the temperature and pressure for a time sufficient to re-sinter the boron-rich cubic boron nitride particles in the apparatus, and (d) recovering the re-sintered polycrystalline cubic boron nitride from the apparatus.

  6. Plasmon-Enhanced Energy Transfer in Photosensitive Nanocrystal Device.

    Science.gov (United States)

    Akhavan, Shahab; Akgul, Mehmet Zafer; Hernandez-Martinez, Pedro Ludwig; Demir, Hilmi Volkan

    2017-06-27

    Förster resonance energy transfer (FRET) interacted with localized surface plasmon (LSP) gives us the ability to overcome inadequate transfer of energy between donor and acceptor nanocrystals (NCs). In this paper, we show LSP-enhanced FRET in colloidal photosensors of NCs in operation, resulting in substantially enhanced photosensitivity. The proposed photosensitive device is a layered self-assembled colloidal platform consisting of separated monolayers of the donor and the acceptor colloidal NCs with an intermediate metal nanoparticle (MNP) layer made of gold interspaced by polyelectrolyte layers. Using LBL assembly, we fabricated and comparatively studied seven types of such NC-monolayer devices (containing only donor, only acceptor, Au MNP-donor, Au MNP-acceptor, donor-acceptor bilayer, donor-Au MNP-acceptor trilayer, and acceptor-Au MNP-donor reverse trilayer). In these structures, we revealed the effect of LSP-enhanced FRET and exciton interactions from the donor NCs layer to the acceptor NCs layer. Compared to a single acceptor NC device, we observed a significant extension in operating wavelength range and a substantial photosensitivity enhancement (2.91-fold) around the LSP resonance peak of Au MNPs in the LSP-enhanced FRET trilayer structure. Moreover, we present a theoretical model for the intercoupled donor-Au MNP-acceptor structure subject to the plasmon-mediated nonradiative energy transfer. The obtained numerical results are in excellent agreement with the systematic experimental studies done in our work. The potential to modify the energy transfer through mastering the exciton-plasmon interactions and its implication in devices make them attractive for applications in nanophotonic devices and sensors.

  7. A Photosensitizer-Loaded DNA Origami Nanosystem for Photodynamic Therapy.

    Science.gov (United States)

    Zhuang, Xiaoxi; Ma, Xiaowei; Xue, Xiangdong; Jiang, Qiao; Song, Linlin; Dai, Luru; Zhang, Chunqiu; Jin, Shubin; Yang, Keni; Ding, Baoquan; Wang, Paul C; Liang, Xing-Jie

    2016-03-22

    Photodynamic therapy (PDT) offers an alternative for cancer treatment by using ultraviolet or visible light in the presence of a photosensitizer and molecular oxygen, which can produce highly reactive oxygen species that ultimately leading to the ablation of tumor cells by multifactorial mechanisms. However, this technique is limited by the penetration depth of incident light, the hypoxic environment of solid tumors, and the vulnerability of photobleaching reduces the efficiency of many imaging agents. In this work, we reported a cellular level dual-functional imaging and PDT nanosystem BMEPC-loaded DNA origami for photodynamic therapy with high efficiency and stable photoreactive property. The carbazole derivative BMEPC is a one- and two-photon imaging agent and photosensitizer with large two-photon absorption cross section, which can be fully excited by near-infrared light, and is also capable of destroying targets under anaerobic condition by generating reactive intermediates of Type I photodynamic reactions. However, the application of BMEPC was restricted by its poor solubility in aqueous environment and its aggregation caused quenching. We observed BMEPC-loaded DNA origami effectively reduced the photobleaching of BMEPC within cells. Upon binding to DNA origami, the intramolecular rotation of BMEPC became proper restricted, which intensify fluorescence emission and radicals production when being excited. After the BMEPC-loaded DNA origami are taken up by tumor cells, upon irradiation, BMEPC could generate free radicals and be released due to DNA photocleavage as well as the following partially degradation. Apoptosis was then induced by the generation of free radicals. This functional nanosystem provides an insight into the design of photosensitizer-loaded DNA origami for effective intracellular imaging and photodynamic therapy.

  8. Advanced smart-photosensitizers for more effective cancer treatment.

    Science.gov (United States)

    Park, Wooram; Cho, Soojeong; Han, Jieun; Shin, Heejun; Na, Kun; Lee, Byeongdu; Kim, Dong-Hyun

    2017-12-19

    Photodynamic therapy (PDT) based upon the use of light and photosensitizers (PSs) has been used as a novel treatment approach for a variety of tumors. It, however, has several major limitations in the clinic: poor water solubility, long-term phototoxicity, low tumor targeting efficacy, and limited light penetration. With advances in nanotechnology, materials science, and clinical interventional imaging procedures, various smart-PSs have been developed for improving their cancer-therapeutic efficacy while reducing the adverse effects. Here, we briefly review state-of-the-art smart-PSs and discuss the future directions of PDT technology.

  9. Photosensitivity to piroxicam: absence of cross-reaction with tenoxicam

    OpenAIRE

    Gonçalo, Margarida; Figueiredo, A; Tavares, P; Fontes-Ribeiro, CA; Teixeira, F; Poiares-Baptista, A

    1992-01-01

    We studied 2 groups of patients. One group of 10 patients had a photosensitive eruption to piroxicam. Another group of 24 patients had positive patch test reactions to thimerosal and thiosalicylic acid and had never taken piroxicam or tenoxicam. Patients were patch tested with thimerosal 0.1% pet., thiosalicylic acid 0.1% pet., salicylic acid 2.0% pet., piroxicam 1 and 5% pet. and tenoxicam 1 and 5% pet. Photopatch tests were also performed with piroxicam and tenoxicam. All 10 patients with p...

  10. Receptor-targeting phthalocyanine photosensitizer for improving antitumor photocytotoxicity.

    Science.gov (United States)

    Xu, Peng; Chen, Jincan; Chen, Zhuo; Zhou, Shanyong; Hu, Ping; Chen, Xueyuan; Huang, Mingdong

    2012-01-01

    Photodynamic therapy (PDT) is a promising therapeutic modality which uses a photosensitizer to capture visible light resulting in phototoxicity in the irradiated region. PDT has been used in a number of pathological indications, including tumor. A key desirable feature of the photosensitizer is the high phototoxicity on tumor cells but not on normal cells. In this study, we conjugate a gonadotropin-releasing hormone (GnRH) to a photosensitizer, Zinc phthalocyanine (ZnPc), in order to enhance its specificity to breast cancer, which over-expresses GnRH receptor. ZnPc has unique advantages over other photosensitizers, but is difficult to derivatize and purify as a single isomer. We previously developed a straight-forward way to synthesize mono-substituted β-carboxy-phthalocyanine zinc (ZnPc-COOH). Photophysical and photochemical parameters of this ZnPc-GnRH conjugate including fluorescence quantum yield (Ф(f)), fluorescence decay time (τ(s)) and singlet oxygen quantum yield (Ф(Δ)) were evaluated and found comparable with that of ZnPc, indicating that addition of a GnRH peptide does not significantly alter the generation of singlet oxygen from ZnPc. Cellular uptakes and phototoxicities of this conjugate were tested and found significantly enhanced on human breast cancer cell lines overexpressing GnRH receptors (MDA-MB-231 and MCF-7 cells) compared to cells with low levels of GnRH receptors, such as human embryonic lung fibroblast (HELF) and human liver carcinoma (HepG2) cells. In addition, the cellular uptake of this conjugate toward MCF-7 cells were found clearly alleviated by a GnRH receptor blocker Cetrorelix, suggesting that the cellular uptake of this conjugate was GnRH receptor-mediated. Put together, these findings revealed that coupling ZnPc with GnRH analogue was an effective way to improve the selectivity of ZnPc towards tumors with over-expressed GnRH receptors.

  11. Photoinduced apoptosis using a peptide carrying a photosensitizer.

    Science.gov (United States)

    Watanabe, Kazunori; Fujiwara, Hayato; Kitamatsu, Mizuki; Ohtsuki, Takashi

    2016-07-01

    A novel molecule, TatBim-Alexa, consisting of the HIV1 Tat cell-penetrating peptide, the Bim apoptosis-inducing peptide, and Alexa Fluor 546 was synthesized for photoinducion of apoptosis. The Alexa Fluor 546 was used as a photosensitizer and covalently attached at the C-terminus of TatBim peptide by the thiol-maleimide reaction. Photo-dependent cytosolic internalization of TatBim-Alexa and photo-dependent apoptosis using TatBim-Alexa were demonstrated in several kinds of mammalian cells including human cancer cell lines. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Electropolymerized supramolecular tetraruthenated porphyrins applied as a voltammetric sensor

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Monize M. da; Ribeiro, Gabriel H.; Faria, Anizio M. de; Bogado, Andre L.; Dinelli, Luis R., E-mail: dinelli@pontal.ufu.br [Universidade Federal de Uberlandia (UFU), Ituiutaba, MG (Brazil). Faculdade de Ciencias Integradas do Pontal; Batista, Alzir A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Quimica

    2013-11-15

    Porphyrin 5,10,15,20-Tetra(4-pyridyl)manganese(III), [Mn-TPyP(H{sub 2}O){sub 2}]PF{sub 6}, and electropolymerized supramolecular porphyrins (ESP), {l_brace}Mn-TPyP(H{sub 2}O){sub 2}[RuCl{sub 3}(dppb)]{sub 4}{r_brace}PF{sub 6} (dppb = 1,4-bis(diphenylphosphine)butane), were synthesized and characterized. A thin solid film of ESP was obtained on a glass carbon electrode surface by a cyclic voltammetry method. The peak current increased with the number of voltammetric cycles, which shows a typical behavior of the species being adsorbed on the surface of the electrode. Cyclic voltammetry was also employed for acetaminophen quantification using an ESP modified electrode. The modified electrode shows a linear relationship between the anodic peak current and the concentration of acetaminophen (in the rage 0.05 to 0.7 mmol L{sup -1}. The performance of the modified electrode was verified by the determination of acetaminophen in a commercial pharmaceutical product and the results were in good agreement with those obtained by a control HPLC method. (author)

  13. Magnetic and electronic properties of porphyrin-based molecular nanowires

    Directory of Open Access Journals (Sweden)

    Jia-Jia Zheng

    2016-01-01

    Full Text Available Using spin-polarized density functional theory calculations, we performed theoretical investigations on the electronic and magnetic properties of transition metal embedded porphyrin-based nanowires (TM-PNWs, TM = Cr, Mn, Co, Ni, Cu, and Zn. Our results indicate that Ni-PNW and Zn-PNW are nonmagnetic while the rest species are magnetic, and the magnetic moments in TM-PNWs and their corresponding isolated monomer structures are found to be the same. In addition, the spin coupling in the magnetic nanowires can be ignored leading to their degenerate AFM and FM states. These results can be ascribed to the weak intermetallic interactions because of the relatively large distances between neighbor TM atoms. Among all TM-PNW structures considered here, only Mn-PNW shows a half-metallic property while the others are predicted to be semiconducting. The present work paves a new way of obtaining ferromagnetic porphyrin-based nanowires with TM atoms distributed separately and orderly, which are expected to be good candidates for catalysts, energy storage and molecular spintronics.

  14. Electron transfer reactions involving porphyrins and chlorophyll a

    International Nuclear Information System (INIS)

    Neta, P.; Scherz, A.; Levanon, H.

    1979-01-01

    Electron transfer reactions involving porphyrins (P) and quinones (Q) have been studied by pulse radiolysis. The porphyrins used were tetraphenylporphyrin (H 2 TPP), its tetracarboxy derivative (H 2 TCPP), the sodium and zinc compounds (Na 2 TPP and ZnTPP), and chlorophyll a (Chl a). These compounds were found to be rapidly reduced by electron transfer from (CH 3 ) 2 CO - . Reduction by (CH 3 ) 2 COH was rapid in aqueous solutions but relatively slow in i-PrOH solutions. Transient spectra of the anion radicals were determined and, in the case of H 2 TCPP - ., a pK = 9.7 was derived for its protonation. Electron-transfer reactions from the anion radical of H 2 TCPP to benzoquinone, duroquinone, 9,10-anthraquinone 2-sulfonate, and methylviologen occur in aqueous solutions with rate constants approx. 10 7 -10 9 M -1 s -1 which depend on the pH and the quinone reduction potential. Reactions of Na 2 TPP - ., ZnTPP - ., and Chl a - . with anthraquinone in basic i-PrOH solutions occur with rate constants approx. 10 9 M -1 s -1 . The spectral changes associated with these electron-transfer reactions as observed over a period of approx. 1 ms indicated, in some cases, the formation of an intermediate complex [P...Q - .]. 8 figures, 2 tables

  15. Characterization of Porphyrin-Co(III)-‘Nitrene Radical’ Species Relevant in Catalytic Nitrene Transfer Reactions

    OpenAIRE

    Goswami, Monalisa; Lyaskovskyy, Volodymyr; Domingos, Sérgio R.; Buma, Wybren Jan; Woutersen, Sander; Troeppner, Oliver; Ivanović-Burmazović, Ivana; Lu, Hongjian; Cui, Xin; Zhang, X. Peter; Reijerse, Edward J.; DeBeer, Serena; van Schooneveld, Matti M.; Pfaff, Florian Felix; Ray, Kallol

    2015-01-01

    To fully characterize the CoIII–‘nitrene radical’ species that are proposed as intermediates in nitrene transfer reactions mediated by cobalt(II) porphyrins, different combinations of cobalt(II) complexes of porphyrins and nitrene transfer reagents were combined, and the generated species were studied using EPR, UV–vis, IR, VCD, UHR-ESIMS, and XANES/XAFS measurements. Reactions of cobalt-(II) porphyrins 1P1 (P1 = meso-tetraphenylporphyrin (TPP)) and 1P2 (P2 = 3,5-DitBu-ChenPhyrin) with organi...

  16. Boron clusters in luminescent materials.

    Science.gov (United States)

    Mukherjee, Sanjoy; Thilagar, Pakkirisamy

    2016-01-21

    In recent times, luminescent materials with tunable emission properties have found applications in almost all aspects of modern material sciences. Any discussion on the recent developments in luminescent materials would be incomplete if one does not account for the versatile photophysical features of boron containing compounds. Apart from triarylboranes and tetra-coordinate borate dyes, luminescent materials consisting of boron clusters have also found immense interest in recent times. Recent studies have unveiled the opportunities hidden within boranes, carboranes and metalloboranes, etc. as active constituents of luminescent materials. From simple illustrations of luminescence, to advanced applications in LASERs, OLEDs and bioimaging, etc., the unique features of such compounds and their promising versatility have already been established. In this review, recent revelations about the excellent photophysical properties of such materials are discussed.

  17. Boron-10 ABUNCL Active Testing

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2013-07-09

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report provides results from testing of the active mode of the General Electric Reuter-Stokes Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) at Los Alamos National Laboratory using sources and fuel pins.

  18. Boron removal from geothermal waters by electrocoagulation.

    Science.gov (United States)

    Yilmaz, A Erdem; Boncukcuoğlu, Recep; Kocakerim, M Muhtar; Yilmaz, M Tolga; Paluluoğlu, Cihan

    2008-05-01

    Most of the geothermal waters in Turkey contain extremely high concentration of boron when they are used for irrigation. The use of geothermal waters for irrigation can results in excess amount deposition of boron in soil. On the other hand, a minimal boron concentration is required for irrigational waters. In this study, electrocoagulation (EC) was selected as a treatment process for the removal of boron from thermal waters obtained from Ilica-Erzurum in Turkey. Current density (CD), pH of solution and temperature of solution were selected as operational parameters. The results showed that boron removal efficiency increased from pH 4.0 to 8.0 and decreased at pH 10.0. Although boron removal efficiency was highest at pH 8.0, energy consumption was very high at this pH value compared to other pH intervals. Boron removal efficiency reached to 95% with increasing current density from 1.5 to 6.0 mA/cm(2), but energy consumption was also increased in this interval. At higher temperatures of solution, such as 313 and 333 K, boron removal efficiency increased. At optimum conditions, boron removal efficiency in geothermal water reached up to 95%.

  19. Removal of boron (B) from waste liquors.

    Science.gov (United States)

    Jiang, J Q; Xu, Y; Simon, J; Quill, K; Shettle, K

    2006-01-01

    This paper explores the use of electrocoagulation to remove boron from waste effluent in comparison with alum coagulation. In treating model test wastes, greater boron removals were achieved with electrocoagulation at low doses than conventional alum coagulation when reaction was undertaken for the same conditions (pH 8.5, and initial boron concentration was 500 mg/L). Al electrocoagulation can achieve good boron removal performance (68.3%) at a dose of 2.1 (as molar ratio of Al:B, and for current density of 62.1 A/m2), while alum coagulation can only achieve the maximum boron removal of 56% at a dose of 2.4. Also, Al electrocoagulation can remove 15-20% more boron than alum coagulation for the same dose compared in the treatment of both model test wastes and industry effluent. The estimation of running costs shows that to achieve 75% boron removal from industry waste effluent, i.e. removing 150 g of boron from 1 m3 of effluent, electrocoagulation was 6.2 times cheaper than alum coagulation. The economic advantage of electrocoagulation in the treatment of boron-containing waste effluent is thus significant.

  20. The boron geochemistry of siliceous sponges

    Science.gov (United States)

    de Leon, A.; Wille, M.; Eggins, S. M.; Ellwood, M. J.

    2009-12-01

    The boron content and isotopic composition (δ11B) of marine carbonate organisms can be linked to the pH of the seawater in which they have grown, making carbonates a useful tool for palaeo-seawater pH reconstruction. A study by Furst (1981) documented unusually high boron concentrations in siliceous sponge spicules, in range from hundreds to a thousand ppm. This observation and the potential for preferential incorporation of the tetrahedral borate species into biogenic silica raises the question as to whether the boron chemistry of biogenic silica might also be influenced by seawater pH. We have measured the boron concentration and isotopic composition of siliceous sponges from the Southern Ocean region, with a view to (1) confirming the observations of Furst (1981), (2) assessing the factors that control boron incorporation and isotopic compositions of sponge silica, and (3) investigating the potentially significant role of siliceous sponges in the marine boron cycle. The measured boron concentrations in a diverse range of both demosponge and hexactinellid sponges confirm the high boron concentrations previously reported. The boron isotope compositions of these sponges vary from around +2‰ to +25‰ and greatly exceed the range in marine carbonates. This isotopic variation is inconsistent with seawater pH control but is correlated with ambient seawater silicon concentration, in a manner that suggests a link to silicon uptake kinetics and demand by sponges.

  1. Mineral resource of the month: boron

    Science.gov (United States)

    Crangle, Robert D.

    2012-01-01

    The article offers information on the mineral, boron. Boron compounds, particularly borates, have more commercial applications than its elemental relative which is a metalloid. Making up the 90% of the borates that are used worldwide are colemanite, kernite, tincal, and ulexite. The main borate deposits are located in the Mojave Desert of the U.S., the Tethyan belt in southern Asia, and the Andean belt of South America. Underground and surface mining are being used in gathering boron compounds. INSETS: Fun facts;Boron production and consumption.

  2. Conduction mechanism in boron carbide

    Science.gov (United States)

    Wood, C.; Emin, D.

    1984-01-01

    Electrical conductivity, Seebeck-coefficient, and Hall-effect measurements have been made on single-phase boron carbides, B(1-x)C(x), in the compositional range from 0.1 to 0.2 X, and between room temperature and 1273 K. The results indicate that the predominant conduction mechanism is small-polaron hopping between carbon atoms at geometrically inequivalent sites.

  3. Synthesis and properties of new chlorin and bacteriochlorin photosensitizers

    Science.gov (United States)

    Mironov, Andrei F.

    1996-01-01

    A series of novel sensitizers, which absorb in the range of 660 - 820 nm, derived from natural occurring chlorophyll and bacteriochlorophyll was synthesized. Biomass of blue-green algae Spirulina platensis was used to prepare chlorophyll a derivatives, and biomass of purple bacteria Rhodobacter capsulatus was applied for preparation of bacteriochlorophyll a. The influence of different substituents on spectral characteristics and the amphipility of the sensitizer was investigated. The route for the synthesis of porphyrin macrocycle with the spacer that bears the isothiocyanate group capable for binding with proteins was proposed. Photophysical properties of chlorin p6, purpurin 18 and their esters in different solvents are investigated. Accumulation of two chlorins in the model Erlich tumor was studied.

  4. Photosensitizing effectiveness of a novel chlorin-based photosensitizer for photodynamic therapy in vitro and in vivo.

    Science.gov (United States)

    Zhang, Li-Jun; Bian, Jun; Bao, Lei-Lei; Chen, Hai-Fei; Yan, Yi-Jia; Wang, Li; Chen, Zhi-Long

    2014-09-01

    Photodynamic therapy (PDT) is a promising noninvasive treatment, which has been approved by the US Food and Drug Administration for the treatment of localized tumors. With the aim to select an appropriate photosensitizer for tumor treatment in PDT, the antitumor effect of a novel chlorin-based photosensitizer, meso-tetra (3-morphlinomethyl-4-methoxyphenyl) chlorin (TMMC) (Fig. 1a) on two types of human malignant tumor cells in vitro and a esophageal cancer model in nude mice, was evaluated in the present paper. Fig. 1 Chemical structure and spectrum properties of TMMC in DMF. a Chemical structure of TMMC in DMF. b UV-Vis absorption spectrum of TMMC in DMF. Its maximum absorbance is at 423 nm, and at 527, 555, 600, 655 nm and 712 nm, also it has absorption. c Emission spectrum of TMMC, which was excited at 514 nm, and its peaks were at 656 and 720 nm. d The matrix of excitation and emission spectra (Ex: 300-550 nm, Em: 600-780 nm) The efficiency of TMMC-PDT in vitro was analyzed by MTT assay and clonogenic assay. The intracellular distribution of photosensitizers was detected with laser scanning confocal microscopy. The accumulation of TMMC in human malignant tumor cells was measured by Fluorescence Spectrometer, and the pathway of cell death was analyzed by flow cytometry. Eca-109 tumor model was used to evaluate the antitumor effects of TMMC-mediated PDT. And the singlet oxygen quantum yield of TMMC was also measured using DPBF as substrate. TMMC shows a singlet oxygen quantum yield of 0.59 and displays a characteristic long wavelength absorption peak at 655 nm. The accumulation of TMMC increased in time-dependent manner, and it was found in cytoplasm and nuclear membranes. TMMC-PDT induced cell death by the major death pathway of necrosis and significantly reduced the growth of Eca-109 tumors in nude mice (180 mW/cm(2), 120 J/cm(2)). The studies suggest that TMMC is an effective photosensitizer for PDT to tumors. Therefore, TMMC has great potentials

  5. A tumor mRNA-mediated bi-photosensitizer molecular beacon as an efficient imaging and photosensitizing agent.

    Science.gov (United States)

    Gao, Yuan; Qiao, Guangming; Zhuo, Linhai; Li, Na; Liu, Ying; Tang, Bo

    2011-05-14

    A bi-photosensitizer molecular beacon (bi-PS MB) is assembled by coupling two PS molecules, respectively, onto the opposite ends of a single MB. The MB can be triggered by a tumor marker-survivin mRNA. Fluorescence and cytotoxic (1)O(2) generation occur effectively in breast cancer cells, but not in normal cells. Compared with a single-PS MB, a bi-PS MB exhibits much-enhanced properties in the signal-to-background ratio and (1)O(2) generation simultaneously. © The Royal Society of Chemistry 2011

  6. Current status of mammalian and human models for predicting drug photosensitivity

    International Nuclear Information System (INIS)

    Harber, L.C.

    1981-01-01

    The status of efforts to develop experimental models for drug photosensitivity reactions in small mammals is reviewed. Tests which are practical and also have a high predictive value in determining photosensitivity hazards to man are the goal of this research. The various animal model systems which have been used are evaluated with respect to these goals

  7. Dosimetry of photosensitization by ultraviolet in patients treated with Haloperidol and Piportil

    International Nuclear Information System (INIS)

    Barros, M. de; Araujo, C.C.

    1982-01-01

    It has been postulated that visible light on UV may induce photosensitization in chronic psycotics, under phenotiazine or butyrofenone therapy. The possible sensitization with UV, in patients with Haloperidol (Johnson and Johnson) or Piportil (Rhodia) treatments is described. Under experimental conditions, a surpassable photosensitizations in reaction groups aren't finding, when paired with the control ones. (M.A.C.) [pt

  8. In-vitro singlet oxygen threshold dose at PDT with Radachlorin photosensitizer

    Science.gov (United States)

    Klimenko, V. V.; Shmakov, S. V.; Kaydanov, N. E.; Knyazev, N. A.; Kazakov, N. V.; Rusanov, A. A.; Bogdanov, A. A.; Dubina, M. V.

    2017-07-01

    In this present study we investigate the Radachlorin photosensitizer accumulation in K562 cells and Hela cells and determined the cell viability after PDT. Using the macroscopic singlet oxygen modeling and cellular photosensitizer concentration the singlet oxygen threshold doses for K562 cells and Hela cells were calculated.

  9. Phosphorescence dynamics of singlet oxygen and Radachlorin photosensitizer in aqueous solution

    Science.gov (United States)

    Belik, V. P.; Beltukova, D. M.; Gadzhiev, I. M.; Semenova, I. V.; Vasyutinskii, O. S.

    2017-07-01

    The luminescence spectrum of aqueous solution of Radachlorin photosensitizer in the near IR spectral range (950-1350 nm) has been determined at the excitation in both the Soret and Q absorption bands. Major sources of the recorded luminescence were analyzed. Kinetics of photosensitizer and singlet oxygen phosphorescence signals were studied by means of time-resolved spectroscopy. The corresponding characteristic lifetimes were determined.

  10. Cholesterol photosensitized oxidation in food and biological systems.

    Science.gov (United States)

    Cardenia, Vladimiro; Rodriguez-Estrada, Maria Teresa; Boselli, Emanuele; Lercker, Giovanni

    2013-03-01

    Lipid oxidation is one of the main chemical degradations occurring in biological systems and leads to the formation of compounds that are related to aging and various chronic and degenerative diseases. The extent of oxidation will depend on the presence of antioxidants/pro-oxidants, the unsaturation degree of fatty acids, and environmental conditions. Lipid oxidation can also affect other molecules that have double bonds in their chemical structures, such as cholesterol. Cholesterol oxidation products (COPs) have been studied in depth, because of their negative and controversial biological effects. The formation of COPs can be particularly favored in the presence of light and photosensitizers, since they generate excited singlet oxygen that rapidly reacts with the double bond by a non radical mechanism and without any induction period. The present review intends to provide an overall and critical picture of cholesterol photosensitized oxidation in food and biological systems, and its possible impact on human health and well-being. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  11. Implication for photosensitive patients of ultraviolet A exposure in vehicles.

    Science.gov (United States)

    Hampton, P J; Farr, P M; Diffey, B L; Lloyd, J J

    2004-10-01

    Photosensitive patients sometimes report disease flares during journeys by car. Window glass blocks all UVB but not all UVA. All car windscreens are made from laminated glass. Side and rear windows are usually made of nonlaminated glass. To determine which types of glass provide most protection from UVA with particular reference to the implications for patients with polymorphic light eruption (PLE). The percentage transmission of UVA was determined for a selection of glass, both laminated and nonlaminated, and with differing colour tints. Laminated glass transmits less UVA than nonlaminated glass. Tinted glass transmits less UVA than clear glass. Nonlaminated clear glass transmitted the highest percentage of UVA (62.8%) and grey laminated glass the lowest (0.9%). A dose of 5 J cm(-2) UVA, enough to trigger PLE in some patients, could be transmitted through clear nonlaminated glass in 30 min but would take 50 h through grey laminated glass. Patients with severe UVA-induced PLE and other photosensitivity disorders may have disease flares from solar UVA transmission through side-window glass. Protective measures such as wearing long-sleeved clothing, keeping the arm beneath the bottom of the window aperture, or choosing tinted and laminated car windows may be helpful.

  12. Photosensitized oxidation of tryptophan and hepatic dysfunction in neonatal gerbils.

    Science.gov (United States)

    Bhatia, J; Rassin, D K

    1985-01-01

    Hepatic dysfunction is a common metabolic complication of parenteral nutrition. Studies in animals have suggested that several amino acids, especially tryptophan, may play a role in the development of hepatic dysfunction. Further, photoirradiation of amino acids in the presence of photosensitizers, such as riboflavin, causes photooxidative changes in several amino acids. The present study was undertaken to determine the effect of tryptophan, after photoirradiation in the presence of riboflavin, on hepatic function in neonatal gerbils. Two-week-old suckling gerbils received approximately 4 mmol/kg/day of light-exposed or nonlight-exposed tryptophan or received saline intraperitoneally for 4 days. An increase in the activity of serum gamma-glutamyl transpeptidase was found in gerbils receiving both light-exposed and nonlight-exposed tryptophan compared to control. Concentrations of tryptophan were significantly higher in animals receiving saline than in the other two groups. There were no significant differences in the major tissue amino acids among the three groups of animals. Our data suggest the role of photosensitized oxidation of tryptophan in the pathogenesis of hepatic dysfunction in neonatal gerbils. It is possible that similar photooxidation occurring during infusion of parenteral amino acid solutions containing vitamins exposed to constant illumination in the newborn nursery is responsible for the observed hepatic dysfunction in parenterally fed neonates.

  13. Evaluation of the skin phototoxicity and photosensitivity of honeybee venom.

    Science.gov (United States)

    Han, Sang Mi; Hong, In Phyo; Woo, Soon Ok; Kim, Se Gun; Jang, He Rye; Park, Kwan Kyu

    2017-12-01

    Bee (Apis mellifera L.) venom (BV) has been used as a cosmetic ingredient owing to its anti-aging, anti-inflammatory, and antibacterial effects. The aim of this study was to assess the skin safety of BV. For this purpose, skin phototoxicity and sensitization tests were conducted in healthy male Hartley guinea pigs. The animals were divided into three groups (n=5) for the phototoxicity test: G1 (negative control), G2 (BV gel treatment), and G3 (positive control). After specified treatments, the animals were irradiated with ultraviolet A (15 J/cm 2 ). The photosensitivity test was also performed in three groups: G4 (negative control, n=5), G5 (BV gel treatment, n=10), and G6 (positive control, n=5). Erythema and edema were observed after 24, 48, and 72 hours in the positive control group, but not in the negative control and BV gel groups. Application of BV to the guinea pig skin had no toxic effects on any clinical signs, body weight, or mortality. In addition, it did not evoke a skin reaction in both either the skin phototoxicity and skin photosensitization tests. Therefore, it can be concluded that BV has the potential to be developed as a drug ingredient for topical uses. © 2017 The Authors. Journal of Cosmetic Dermatology Published by Wiley Periodicals, Inc.

  14. Beta-lactamase targeted enzyme activatable photosensitizers for antimicrobial PDT

    Science.gov (United States)

    Zheng, Xiang; Verma, Sarika; Sallum, Ulysses W.; Hasan, Tayyaba

    2009-06-01

    Photodynamic therapy (PDT) as a treatment modality for infectious disease has shown promise. However, most of the antimicrobial photosensitizers (PS) non-preferentially accumulate in both bacteria and host tissues, causing host tissue phototoxicity during treatment. We have developed a new antimicrobial PDT strategy which exploits beta-lactam resistance mechanism, one of the major drug-resistance bacteria evolved, to achieve enhanced target specificity with limited host damage. Our strategy comprises a prodrug construct with a PS and a quencher linked by beta-lactam ring, resulting in a diminished phototoxicity. This construct, beta-lactamase enzyme-activated-photosensitizer (beta-LEAP), can only be activated in the presence of both light and bacteria, and remains inactive elsewhere such as mammalian tissue. Beta-LEAP construct had shown specific cleavage by purified beta-lactamase and by beta-lactamase over-expressing methicillin resistant Staphylococcus aureus (MRSA). Specific photodynamic toxicity was observed towards MRSA, while dark and light toxicity were equivalent to reference strains. The prodrug design, synthesis and photophysical properties will be discussed.

  15. The circadian response of intrinsically photosensitive retinal ganglion cells.

    Directory of Open Access Journals (Sweden)

    Andrew J Zele

    Full Text Available Intrinsically photosensitive retinal ganglion cells (ipRGC signal environmental light level to the central circadian clock and contribute to the pupil light reflex. It is unknown if ipRGC activity is subject to extrinsic (central or intrinsic (retinal network-mediated circadian modulation during light entrainment and phase shifting. Eleven younger persons (18-30 years with no ophthalmological, medical or sleep disorders participated. The activity of the inner (ipRGC and outer retina (cone photoreceptors was assessed hourly using the pupil light reflex during a 24 h period of constant environmental illumination (10 lux. Exogenous circadian cues of activity, sleep, posture, caffeine, ambient temperature, caloric intake and ambient illumination were controlled. Dim-light melatonin onset (DLMO was determined from salivary melatonin assay at hourly intervals, and participant melatonin onset values were set to 14 h to adjust clock time to circadian time. Here we demonstrate in humans that the ipRGC controlled post-illumination pupil response has a circadian rhythm independent of external light cues. This circadian variation precedes melatonin onset and the minimum ipRGC driven pupil response occurs post melatonin onset. Outer retinal photoreceptor contributions to the inner retinal ipRGC driven post-illumination pupil response also show circadian variation whereas direct outer retinal cone inputs to the pupil light reflex do not, indicating that intrinsically photosensitive (melanopsin retinal ganglion cells mediate this circadian variation.

  16. Long-wavelength photosensitivity in coral planula larvae.

    Science.gov (United States)

    Mason, Benjamin M; Cohen, Jonathan H

    2012-04-01

    Light influences the swimming behavior and settlement of the planktonic planula larvae of coral, but little is known regarding the photosensory biology of coral at this or any life-history stage. Here we used changes in the electrical activity of coral planula tissue upon light flashes to investigate the photosensitivity of the larvae. Recordings were made from five species: two whose larvae are brooded and contain algal symbionts (Porites astreoides and Agaricia agaricites), and three whose larvae are spawned and lack algal symbionts (Acropora cervicornis, Acropora palmata,and Montastrea faveolata). Photosensitivity originated from the coral larva rather than from, or in addition to, its algal symbionts as species with and without symbionts displayed similar tissue-level electrical responses to light. All species exhibited as much (or more) sensitivity to red stimuli as to blue/green stimuli, which is consistent with a role for long-wavelength visible light in the preference for substrata observed during settlement and in facilitating vertical positioning of larvae in the water column.

  17. Propagation of photosensitive chemical waves on the circular routes.

    Science.gov (United States)

    Kitahata, Hiroyuki; Yamada, Akiko; Nakata, Satoshi; Ichino, Takatoshi

    2005-06-09

    The propagation of chemical waves in the photosensitive Belousov-Zhabotinsky (BZ) reaction was investigated using an excitable field in the shape of a circular ring or figure "8" that was drawn by computer software and then projected on a film soaked with BZ solution using a liquid-crystal projector. For a chemical wave in a circular reaction field, the shape of the chemical wave was investigated depending on the ratio of the inner and outer radii. When two chemical waves were generated on a field shaped like a figure "8" (one chemical wave in each circle) as the initial condition, the location of the collision of the waves either was constant or alternated depending on the degree of overlap of the two circular rings. These experimental results were analyzed on the basis of a geometrical discussion and theoretically reproduced on the basis of a reaction-diffusion system using a modified Oregonator model. These results suggest that the photosensitive BZ reaction may be useful for creating spatio-temporal patterns depending on the geometric arrangement of excitable fields.

  18. Synthesis, Spectroscopic, and Biological Studies on New Zirconium(IV) Porphyrins with Axial Ligand

    Science.gov (United States)

    Bajju, Gauri D.; Devi, Gita; Katoch, Sapna; Bhagat, Madhulika; Deepmala; Ashu; Kundan, Sujata; Anand, Sunil Kumar

    2013-01-01

    A series of parasubstituted tetraphenylporphyrin zirconium(IV) salicylate complexes (SA/5-SSAZr(IV)RTPP, R = p-H, p-CH3, p-NO2, p-Cl, SA = salicylate, and 5-SSA = 5-sulfosalicylate) have been synthesized, and the spectral properties of free base porphyrins, their corresponding metallated, and axially ligated zirconium(IV) porphyrin compounds were compared with each other. A detailed analysis of ultraviolet-visible (UV-vis), proton nulcear magnetic resonance (1H NMR) spectroscopy, infrared (IR) spectroscopy, and elemental analysis suggested the transformation from free base porphyrins to zirconium(IV) porphyrins. The ability of the metal in this complex for extra coordination of solvent molecules was confirmed by ESI-MS spectra. Besides the fluorescence, cyclic voltammetry, and thermogravimetric studies, the complexes were also screened for antimicrobial and anticancer activities. Among all the complexes, 5-SSAZr(p-NO2TPP) shows high antibacterial activity. PMID:24106455

  19. Methods and intermediates for the synthesis of dipyrrin-substituted porphyrinic macrocycles

    Science.gov (United States)

    Yu, Lianhe; Muthukumaran, Kannan; Sreedharan, Prathapan; Lindsey, Jonathan S.

    2010-05-25

    The present invention provides dipyrrin substituted porphyrinic macrocycles, intermediates useful for making the same, and methods of making the same. Such compounds may be used for purposes including the making of molecular memory devices, solar cells and light harvesting arrays.

  20. Synthesis, Spectroscopic, and Biological Studies on New Zirconium(IV) Porphyrins with Axial Ligand.

    Science.gov (United States)

    Bajju, Gauri D; Devi, Gita; Katoch, Sapna; Bhagat, Madhulika; Deepmala; Ashu; Kundan, Sujata; Anand, Sunil Kumar

    2013-01-01

    A series of parasubstituted tetraphenylporphyrin zirconium(IV) salicylate complexes (SA/5-SSAZr(IV)RTPP, R = p-H, p-CH3, p-NO2, p-Cl, SA = salicylate, and 5-SSA = 5-sulfosalicylate) have been synthesized, and the spectral properties of free base porphyrins, their corresponding metallated, and axially ligated zirconium(IV) porphyrin compounds were compared with each other. A detailed analysis of ultraviolet-visible (UV-vis), proton nulcear magnetic resonance ((1)H NMR) spectroscopy, infrared (IR) spectroscopy, and elemental analysis suggested the transformation from free base porphyrins to zirconium(IV) porphyrins. The ability of the metal in this complex for extra coordination of solvent molecules was confirmed by ESI-MS spectra. Besides the fluorescence, cyclic voltammetry, and thermogravimetric studies, the complexes were also screened for antimicrobial and anticancer activities. Among all the complexes, 5-SSAZr(p-NO2TPP) shows high antibacterial activity.

  1. Chiroptical properties of an alternatingly functionalized cellotriose bearing two porphyrin groups

    Science.gov (United States)

    Alternatingly functionalized cellulose molecules have potential applications in optoelectronics and molecular receptors. For example, cellulose-based solar cells have been proposed. As a prototype for such molecules, the trisaccharide fragment of cellulose was modified by attachment of porphyrin gro...

  2. Functionalized Nanostructures: Redox-Active Porphyrin Anchors for Supramolecular DNA Assemblies

    KAUST Repository

    Börjesson, Karl

    2010-09-28

    We have synthesized and studied a supramolecular system comprising a 39-mer DNA with porphyrin-modified thymidine nucleosides anchored to the surface of large unilamellar vesicles (liposomes). Liposome porphyrin binding characteristics, such as orientation, strength, homogeneity, and binding site size, was determined, suggesting that the porphyrin is well suited as a photophysical and redox-active lipid anchor, in comparison to the inert cholesterol anchor commonly used today. Furthermore, the binding characteristics and hybridization capabilities were studied as a function of anchor size and number of anchoring points, properties that are of importance for our future plans to use the addressability of these redox-active nodes in larger DNA-based nanoconstructs. Electron transfer from photoexcited porphyrin to a lipophilic benzoquinone residing in the lipid membrane was characterized by steady-state and time-resolved fluorescence and verified by femtosecond transient absorption. © 2010 American Chemical Society.

  3. Modifications of Porphyrins and Hydroporphyrins for Their Solubilization in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Michael Luciano

    2017-06-01

    Full Text Available The increasing popularity of porphyrins and hydroporphyrins for use in a variety of biomedical (photodynamic therapy, fluorescence tagging and imaging, photoacoustic imaging and technical (chemosensing, catalysis, light harvesting applications is also associated with the growing number of methodologies that enable their solubilization in aqueous media. Natively, the vast majority of synthetic porphyrinic compounds are not water-soluble. Moreover, any water-solubility imposes several restrictions on the synthetic chemist on when to install solubilizing groups in the synthetic sequence, and how to isolate and purify these compounds. This review summarizes the chemical modifications to render synthetic porphyrins water-soluble, with a focus on the work disclosed since 2000. Where available, practical data such as solubility, indicators for the degree of aggregation, and special notes for the practitioner are listed. We hope that this review will guide synthetic chemists through the many strategies known to make porphyrins and hydroporphyrins water soluble.

  4. Synthesis and characterization of a novel meso-porphyrin and its metallo derivatives

    Directory of Open Access Journals (Sweden)

    Paulo Cesar Bega

    2014-02-01

    Full Text Available There has been a growing interest in the properties of substituted meso-tetraarylporphyrins and metallo porphyrins as catalysts for oxidation of hydrocarbons, oxygen detection, among others. This work describes the synthesis of a new porphyrin, 5,10,15,20-tetrakis(4-butoxy-3-methoxyphenylporphyrin, and its metallo complexes. Herein it was used a readily available reactant, vanillin, as starting material which was submitted to alkylation with n-bromobutane affording the synthetic precursor. The desired porphyrin was obtained by reacting the O-alkylated aldehyde with pyrrole in the presence of propionic acid (Alder-Longo method. The purified porphyrin was then subjected to the metallation process using iron (II and manganese (II salts. The synthesized compounds were characterized by IR, UV-Vis, NMR and EPR spectroscopy.

  5. Acid-base and coordination properties of Meso-substituted porphyrins in nonaqueous solutions

    Science.gov (United States)

    Pukhovskaya, S. G.; Nam, Dao Tkhe; Fien, Chan Ding; Domanina, E. N.; Ivanova, Yu. B.; Semeikin, A. S.

    2017-09-01

    Acid-base and coordination properties of alkyl and aryl meso-substituted porphyrins are studied spectrophotometrically in nonaqueous solutions. It is found that the nature of the substituent greatly affects the basicity of ligands for porphyrins characterized by a flat structure of macrocycle. The electronic effects of substituents have a much weaker influence on the kinetics of complexing. These effects could be due to the opposite orientation of some factors: an increase in the basicity and stability of the N-H bonds of porphyrin reaction centers. Dissociation constants p K b of the cationic forms of meso-substituted derivatives of porphyrin are measured. The values of p K b are in good agreement with classic concepts of the nature of substituents, particularly those indirectly included in the macrocycle through phenyl buffer rings.

  6. Electrocatalytic miRNA Detection Using Cobalt Porphyrin-Modified Reduced Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Camille De Souza

    2014-06-01

    Full Text Available Metalated porphyrins have been described to bind nucleic acids. Additionally, cobalt porphyrins present catalytic properties towards oxygen reduction. In this work, a carboxylic acid-functionalized cobalt porphyrin was physisorbed on reduced graphene oxide, then immobilized on glassy carbon electrodes. The carboxylic groups were used to covalently graft amino-terminated oligonucleotide probes which are complementary to a short microRNA target. It was shown that the catalytic oxygen electroreduction on cobalt porphyrin increases upon hybridization of miRNA strand (“signal-on” response. Current changes are amplified compared to non-catalytic amperometric system. Apart from oxygen, no added reagent is necessary. A limit of detection in the sub-nanomolar range was reached. This approach has never been described in the literature.

  7. Light energy collection in a porphyrin-imide-corrole ensemble.

    Science.gov (United States)

    Ciuciu, Adina I; Flamigni, Lucia; Voloshchuk, Roman; Gryko, Daniel T

    2013-05-01

    An assembly consisting of three units, that is, a meso-substituted corrole (C3), 1,8 naphthaleneimide (NIE), and a Zn porphyrin (ZnP), has been synthesized. NIE is connected to C3 through a 1,3-phenylene bridge and to the ZnP unit through a direct C-C bond. The convergent synthetic strategy includes the preparation of a trans-A2B-corrole possessing the imide unit, followed by Sonogashira coupling with a meso-substituted A3B-porphyrin. The photophysical processes in the resulting triad ZnP-NIE-C3 are examined and compared with those of the corresponding C3-NIE dyad and the constituent reference models C3, NIE, and ZnP. Excitation of the NIE unit in C3-NIE leads to a fast energy transfer of 98 % efficiency to C3 with a rate k(en) =7.5×10(10) s(-1), whereas excitation of the corrole unit leads to a reactivity of the excited state identical to that of the model C3, with a deactivation rate to the ground state k=2.5×10(8) s(-1). Energy transfer to C3 and to ZnP moieties follows excitation of NIE in the triad ZnP-NIE-C3. The rates are k(en) =7.5×10(10) s(-1) and k(en) =2.5×10(10) s(-1) for the sensitization of the C3 and ZnP unit, respectively. The light energy transferred from NIE to Zn porphyrin unit is ultimately funneled to the corrole component, which is the final recipient of the excitation energy absorbed by the different components of the array. The latter process occurs with a rate k(en) =3.4×10(9) s(-1) and 89 % efficiency. Energy transfer processes take place in all cases by a Förster (dipole-dipole) mechanism. The theory predicts quite satisfactorily the rate for the ZnP/C3 couple, where components are separated by about 23 Å, but results in calculated rates that are one to two orders of magnitude higher for the couples NIE/ZnP (D/A) and NIE/C3, which are separated by distances of about 14 and 10 Å, respectively. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Porphyrin electrode films prepared by electrooxidation of metalloprotoporphyrins

    Energy Technology Data Exchange (ETDEWEB)

    Macor, K.A.; Spiro, T.G.

    1983-08-24

    Electrooxidation in organic solvents of the dimethyl esters of several metalloprotoporphyrins (PP) (Ni/sup II/PP, Zn/sup II/PP, Co/sup II/PP, (Fe/sup III/PP)Cl, (Fe/sup III/PP)/sub 2/O, and (Cr/sup III/PP)/sub 2/O) leads to the deposition of thick (approx. 1000 monolayer equivalents), electroactive porphyrin films, which have been characterized by cyclic voltammetry and absorption spectroscopy on transparent SnO/sub 2/ electrodes. The films are stable toward organic solvents and aqueous acids and bases, but are removed by treatment with hot concentrated acids. The resonance Raman spectrum of the NiPP film indicates that one of the two vinyl groups is saturated on most of the porphyrin units. Deposition continues for some minutes after the current is interrupted. This evidence is consistent with a mechanism involving electroinitiated cationic vinyl polymerization. No film is formed if the metal, rather than the ring, is oxidized. Thus the first oxidation step of Co/sup II/PP, to (Co/sup III/PP)/sup +/, does not support film formation (although the potential is as high as for ring oxidation in ZnPP), but the second step, to (Co/sup III/PP)/sup 2 +/, does. Lack of film formation for (Mn/sup III/PP)Cl and (Cr/sup IV/PP)O suggests metal, rather than ring oxidation, to Mn/sup IV/ and Cr/sup V/. However, (CrPP)/sub 2/O oxidation does produce a film, suggesting ring oxidation, analogous to (FePP)/sub 2/O, which also produces a film. However, while (CrPP)/sub 2/O is incorporated intact into the film, the (FePP)/sub 2/O film contains monomer units. Incorporation of other metal ions can be accomplished by soaking a ZnPP-coated electrode in H/sub 2/SO/sub 4/ followed by contact wtih a solution of the metal dihalide in refluxing DMF. The porphyrin sites are accessible to small ions, as shown by chloride coordination of ZnPP film upon soaking in chloride solution. 49 references, 13 figures, 1 table.

  9. Spectral properties of porphyrins in the systems with layered silicates

    International Nuclear Information System (INIS)

    Ceklovsky, A.

    2009-03-01

    This work is focused on investigation of hybrid materials based on layered silicates, representing host inorganic component, and porphyrin dyes as organic guest. Aqueous colloidal dispersions, as well as thin solid films of layered silicate/porphyrin systems were studied. Modification of photophysical properties, such as absorption and fluorescence of molecules, adsorbed or incorporated in layered silicate hosts, were studied mainly to spread the knowledge about the environments suitable for incorporating aromatic compounds, providing photoactive properties of potential technological interest. TMPyP cations interact with the surfaces of layered silicates via electrostatic interactions. The extent of dye adsorption on colloidal particles of the silicates is influenced by the CEC values and swelling ability of silicates. Interaction of porphyrins with layered silicate hosts leads to significant changes of dye spectral properties. One of the key parameters that has a crucial impact on this interaction is the layer charge of silicate template. Other factors influence the resulting spectral properties of hybrid systems, such as the method of hybrid material preparation, the material's type (colloid, film), and the modification of the silicate host. Molecular orientation studies using linearly-polarized spectroscopies in VIS and IR regions revealed that TMPyP molecules were oriented in almost parallel fashion with respect to the silicate surface plane. Slightly higher values of the orientation angle of TMPyP transition moment were observed for the TMPyP/FHT system. Thus, flattening of the guest TMPyP molecules is the next important factor (mainly in the systems with lower layer charge), influencing its spectral properties upon the interaction with layered silicates. Fluorescence was effectively quenched in the systems based on solid films prepared from the high concentration of the dye (10-3 mol.dm-3). The quenching is most probably related to the structure of the

  10. Modulation of biodistribution, pharmacokinetics, and photosensitivity with the delivery vehicle of a bacteriochlorin photosensitizer for photodynamic therapy.

    Science.gov (United States)

    Saavedra, Raquel; Rocha, Luis B; Dąbrowski, Janusz M; Arnaut, Luis G

    2014-02-01

    Intravenous (i.v.) formulations with various amounts of organic solvents [PEG400 , propylene glycol (PG), cremophor EL (CrEL)] were used to deliver a fluorinated sulfonamide bacteriochlorin to mice, rats, and minipigs. Biodistribution studies in mice showed that a low-content CrEL formulation combines high bioavailability with high tumor-to-muscle and tumor-to-skin ratios. This formulation was also the most successful in the photodynamic therapy of mice with subcutaneously implanted CT26 murine colon adenocarcinoma tumors. Pharmacokinetic studies in mice and minipigs revealed that with the same low CrEL formulation, the half-life of the photosensitizer in the central compartment was longer in minipigs. Differences in biodistribution with the various formulations, and in pharmacokinetics between the two animal species with the same formulation, are attributed to the interaction of the formulations with low-density lipoproteins (LDLs). Skin photosensitivity studies in rats showed that 30 min exposure of the skin to a solar simulator 7 days after i.v. administration of the fluorinated sulfonamide bacteriochlorin at 1 mg kg(-1) did not elicit significant skin reactions. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. N-annulated perylene fused porphyrins with enhanced near-IR absorption and emission

    KAUST Repository

    Jiao, Chongjun

    2010-09-17

    N-Annulated perylene fused porphyrins 1 and 2 were synthesized by oxidative dehydrogenation using a Sc(OTf)3/DDQ system. These newly synthesized hybrid molecules are highly soluble in organic solvents and exhibit remarkably intense near-IR absorption, as well as detectable photoluminescence quantum yields, all of which are comparable to or even exceed those of either meso-β doubly linked porphyrin dimer/trimer or bis/tri-N-annulated rylenes. © 2010 American Chemical Society.

  12. Sequence-targeted chemical modifications of nucleic acids by complementary oligonucleotides covalently linked to porphyrins.

    OpenAIRE

    Trung Le Doan; Perrouault, L; Chassignol, M; Nguyen, T T; Hélène, C

    1987-01-01

    Oligo-heptathymidylates covalently linked to porphyrins bind to complementary sequences and can induce local damages on the target molecule. In dark reactions, iron porphyrin derivatives exhibited various chemical reactivities resulting in base oxidation, crosslinking and chain scission reactions. Reactions induced by reductants, such as ascorbic acid, dithiothreitol or mercapto-propionic acid, led to very localised reactions. A single base was the target for more than 50% of the damages. Oxi...

  13. Boron carbide synthesis by carbothermic reduction of boron oxide

    International Nuclear Information System (INIS)

    Castro, A.R.M. de; Paschoal, J.O.A.

    1988-01-01

    Boron carbide (B 4 C) is a ceramic material of technological applications due to its extreme hardness and high chemical as well as thermal stability. Some parameters of the process for obtaining B 4 C by carbothermic reduction of B 2 O 3 have been determined. The starting powders and the final products have been analysed by chemical, spectrographic and X-ray diffraction methods. The results show that the B 4 C obtained by the carbothermic reduction process is suitable for applications with a definite determination of the free carbon content. (author) [pt

  14. Copolymerisation of Propylene Oxide and Carbon Dioxide by Dinuclear Cobalt Porphyrins

    KAUST Repository

    Anderson, Carly E.

    2013-09-18

    Two dinuclear cobalt porphyrins comprising different structural tethering motifs at the porphyrin periphery were synthesised, along with a representative mononuclear cobalt porphyrin, and their catalytic activities tested towards carbon dioxide-propylene oxide copolymerisation in the presence of bis(triphenylphosphoranyl)ammonium chloride cocatalyst. The catalytic activities of the mononuclear and the bis-para-tethered dinuclear cobalt porphyrin with selective formation of poly(propylene carbonate) are largely comparable, showing no benefit of dinuclearity in contrast to the case of cobalt salen complexes and suggesting that polymer growth proceeds exclusively from one metal centre. The alternative bis-ortho-tethered porphyrin demonstrated considerably reduced activity, with dominant formation of cyclic propylene carbonate, as a result of hindered substrate approach at the metal centre. Time-resolved UV/Vis spectroscopic studies suggested a general intolerance of the cobalt(III) porphyrin catalysts towards the copolymerisation conditions in the absence of carbon dioxide pressure, leading to catalytically inactive cobalt(II) species. In the presence of carbon dioxide, the bis-ortho-tethered catalyst showed the fastest deactivation, which is related to an unfavourable steric arrangement of the linker fragment, as was also confirmed by NMR spectroscopic measurements. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Fluorescence quenching behaviour of uric acid interacting with water-soluble cationic porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Makarska-Bialokoz, Magdalena, E-mail: makarska@hektor.umcs.lublin.pl [Department of Inorganic Chemistry, Maria Curie-Sklodowska University M. C. Sklodowska Sq. 2, 20-031 Lublin (Poland); Borowski, Piotr [Faculty of Chemistry, Maria Curie-Sklodowska University M. C. Sklodowska Sq. 3, 20-031 Lublin (Poland)

    2015-04-15

    The process of association between 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H{sub 2}TTMePP) and uric acid as well as its sodium salt has been studied in aqueous NaOH solution analysing its absorption and steady-state fluorescence spectra. The fluorescence quenching effect observed during interactions porphyrin-uric acid compounds points at the fractional accessibility of the fluorophore for the quencher. The association and fluorescence quenching constants are of the order of magnitude of 10{sup 5} mol{sup −1}. The fluorescence lifetimes and the quantum yields of the porphyrin anionic form were established. The results demonstrate that uric acid and its sodium salt can interact with H{sub 2}TTMePP at basic pH and through formation of stacking complexes are able to quench its ability to emission. - Highlights: • Association study of water soluble cationic porphyrin with uric acid. • Porphyrin absorption spectra undergo the bathochromic and hypochromic effects. • Uric acid interacts with porphyrin in inhibiting manner, quenching its emission. • Fluorescence quenching effect testifies for the partial inactivation of a porphyrin. • The association and fluorescence quenching constants were calculated.

  16. Fluorescence quenching behaviour of uric acid interacting with water-soluble cationic porphyrin

    International Nuclear Information System (INIS)

    Makarska-Bialokoz, Magdalena; Borowski, Piotr

    2015-01-01

    The process of association between 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H 2 TTMePP) and uric acid as well as its sodium salt has been studied in aqueous NaOH solution analysing its absorption and steady-state fluorescence spectra. The fluorescence quenching effect observed during interactions porphyrin-uric acid compounds points at the fractional accessibility of the fluorophore for the quencher. The association and fluorescence quenching constants are of the order of magnitude of 10 5 mol −1 . The fluorescence lifetimes and the quantum yields of the porphyrin anionic form were established. The results demonstrate that uric acid and its sodium salt can interact with H 2 TTMePP at basic pH and through formation of stacking complexes are able to quench its ability to emission. - Highlights: • Association study of water soluble cationic porphyrin with uric acid. • Porphyrin absorption spectra undergo the bathochromic and hypochromic effects. • Uric acid interacts with porphyrin in inhibiting manner, quenching its emission. • Fluorescence quenching effect testifies for the partial inactivation of a porphyrin. • The association and fluorescence quenching constants were calculated

  17. Light-harvesting and ultrafast energy migration in porphyrin-based metal-organic frameworks.

    Science.gov (United States)

    Son, Ho-Jin; Jin, Shengye; Patwardhan, Sameer; Wezenberg, Sander J; Jeong, Nak Cheon; So, Monica; Wilmer, Christopher E; Sarjeant, Amy A; Schatz, George C; Snurr, Randall Q; Farha, Omar K; Wiederrecht, Gary P; Hupp, Joseph T

    2013-01-16

    Given that energy (exciton) migration in natural photosynthesis primarily occurs in highly ordered porphyrin-like pigments (chlorophylls), equally highly ordered porphyrin-based metal-organic frameworks (MOFs) might be expected to exhibit similar behavior, thereby facilitating antenna-like light-harvesting and positioning such materials for use in solar energy conversion schemes. Herein, we report the first example of directional, long-distance energy migration within a MOF. Two MOFs, namely F-MOF and DA-MOF that are composed of two Zn(II) porphyrin struts [5,15-dipyridyl-10,20-bis(pentafluorophenyl)porphinato]zinc(II) and [5,15-bis[4-(pyridyl)ethynyl]-10,20-diphenylporphinato]zinc(II), respectively, were investigated. From fluorescence quenching experiments and theoretical calculations, we find that the photogenerated exciton migrates over a net distance of up to ~45 porphyrin struts within its lifetime in DA-MOF (but only ~3 in F-MOF), with a high anisotropy along a specific direction. The remarkably efficient exciton migration in DA-MOF is attributed to enhanced π-conjugation through the addition of two acetylene moieties in the porphyrin molecule, which leads to greater Q-band absorption intensity and much faster exciton-hopping (energy transfer between adjacent porphyrin struts). The long distance and directional energy migration in DA-MOF suggests promising applications of this compound or related compounds in solar energy conversion schemes as an efficient light-harvesting and energy-transport component.

  18. Real-time porphyrin detection in plaque and caries: a case study

    Science.gov (United States)

    Timoshchuk, Mari-Alina I.; Ridge, Jeremy S.; Rugg, Amanda L.; Nelson, Leonard Y.; Kim, Amy S.; Seibel, Eric J.

    2015-02-01

    An ultrathin scanning fiber endoscope, originally developed for cancer diagnosis, was used in a case study to locate plaque and caries. The imaging system incorporated software mitigation of background auto-fluorescence (AF). In conventional fluorescence imaging, varying AF across a tooth surface can mask low-level porphyrin signals. Laser-induced auto-fluorescence signals of dental tissue excited using a 405-nm laser typically produce fluorescence over a wavelength range extending from 440-nm to 750-nm. Anaerobic bacterial metabolism produces various porphyrin species (eg. protoporphyrin IX) that are located in carious enamel, dentin, gingivitis sites, and plaque. In our case study, these porphyrin deposits remained as long as one day after prophylaxis. Imaging the tooth surface using 405-nm excitation and subtracting the natural AF enhances the image contrast of low-level porphyrin deposits, which would otherwise be masked by the high background AF. In a case study, healthy tissues as well as sites of early and advanced caries formations were scanned for visual and quantitative signs of red fluorescence associated with porphyrin species using a background mitigation algorithm. Initial findings show increasing amplitudes of red fluorescence as caries severity increases from early to late stages. Sites of plaque accumulation also displayed red fluorescence similar to that found in carious dental tissue. The use of real-time background mitigation of natural dental AF can enhance the detection of low porphyrin concentrations that are indicators of early stage caries formation.

  19. ATP-dependent mitochondrial porphyrin importer ABCB6 protects against phenylhydrazine toxicity.

    Science.gov (United States)

    Ulrich, Dagny L; Lynch, John; Wang, Yao; Fukuda, Yu; Nachagari, Deepa; Du, Guoqing; Sun, Daxi; Fan, Yiping; Tsurkan, Lyudmila; Potter, Philip M; Rehg, Jerold E; Schuetz, John D

    2012-04-13

    Abcb6 is a mammalian mitochondrial ATP-binding cassette (ABC) transporter that regulates de novo porphyrin synthesis. In previous studies, haploinsufficient (Abcb6(+/-)) embryonic stem cells showed impaired porphyrin synthesis. Unexpectedly, Abcb6(-/-) mice derived from these stem cells appeared phenotypically normal. We hypothesized that other ATP-dependent and/or -independent mechanisms conserve porphyrins. Here, we demonstrate that Abcb6(-/-) mice lack mitochondrial ATP-driven import of coproporphyrin III. Gene expression analysis revealed that loss of Abcb6 results in up-regulation of compensatory porphyrin and iron pathways, associated with elevated protoporphyrin IX (PPIX). Phenylhydrazine-induced stress caused higher mortality in Abcb6(-/-) mice, possibly because of sustained elevation of PPIX and an inability to convert PPIX to heme despite elevated ferrochelatase levels. Therefore, Abcb6 is the sole ATP-dependent porphyrin importer, and loss of Abcb6 produces up-regulation of heme and iron pathways necessary for normal development. However, under extreme demand for porphyrins (e.g. phenylhydrazine stress), these adaptations appear inadequate, which suggests that under these conditions Abcb6 is important for optimal survival.

  20. Occurrence and distribution of metals and porphyrins in Nigerian coal minerals

    Energy Technology Data Exchange (ETDEWEB)

    Olajire, A.A.; Ameen, A.B.; Abdul-Hammed, M.; Adekola, F.A [Ladoke Akintola University of Technology, Ogbomoso (Nigeria). Department of Pure and Applied Chemistry

    2007-12-15

    The metal contents of Nigerian coal minerals were analyzed using an atomic absorption spectrophotometer. Calcium, Na, and Fe occurred as the major elements with concentrations ranging from 9782 {mu}g/g for Ca to 432 {mu}g/g for Na whereas K, Mg, Mn, Ni, Cr, Zn, Pb, and Cu, which occurred at trace levels ranged from 673.73 {mu}g/g for Mg to 2.97 {mu}g/g for Mn. The results of the quantitative analysis of porphyrins extracted from the coal minerals showed that Onyeama coal has the highest amount of porphyrins while Okpara has the lowest. The porphyrins were qualitatively characterized by a combination of thin layer chromatography (TLC), infrared, and ultraviolet-visible spectrophotometers. The results of the mid infrared analysis (MIR) showed the presence of absorption bands at 3440 cm{sup -1} to 3450 cm{sup -1} and 1640 cm{sup -1} to 1680 cm{sup -1}, which are owing to the stretching vibrations of N-H and C=C of aromatics, with C-H out of plane (oop) bending vibrations at wavenumbers less than 900 cm{sup -1}, all of which are characteristic absorptions of porphyrin free base. The ultraviolet-visible data showed prominent peaks at about 400 nm and at wavelength ranges of 535 nm - 550 nm and 565 nm - 600 nm for the coal porphyrins analyzed. The geochemical significance of the metals and porphyrins in coal minerals are discussed.

  1. Optical Humidity Sensing Using Transparent Hybrid Film Composed of Cationic Magnesium Porphyrin and Clay Mineral.

    Science.gov (United States)

    Fujimura, Takuya; Shimada, Tetsuya; Sasai, Ryo; Takagi, Shinsuke

    2018-03-13

    A transparent hybrid film composed of cationic magnesium porphyrin and clay mineral was developed, and its chromic behavior depending on relative humidity (RH) was investigated. The hybrid film was obtained via intercalation of magnesium porphyrin into clay film; magnesium porphyrin was intercalated into the interlayer spaces of the clay mineral without aggregation. The absorption spectra of the hybrid film showed red shifts compared to the aqueous solution of magnesium porphyrin because of the π-conjugated system extension with coplanarization of the meso-substituted pyridinium group and porphyrin ring. The absorption maximum of the hybrid film was gradually shifted to a shorter wavelength, and the color of the hybrid film was changed with increasing RH. The X-ray diffraction measurement suggested that the basal space of clay was expanded with increasing RH, indicating that the interlayer space of clay was expanded by water adsorption, and the spectral shift was induced by the change in coplanarization degree between the porphyrin ring and meso-substituted pyridinium groups.

  2. Boron Carbides As Thermo-electric Materials

    Science.gov (United States)

    Wood, Charles

    1988-01-01

    Report reviews recent theoretical and experimental research on thermoelectric materials. Recent work with narrow-band semiconductors demonstrated possibility of relatively high thermoelectric energy-conversion efficiencies in materials withstanding high temperatures needed to attain such efficiencies. Among promising semiconductors are boron-rich borides, especially boron carbides.

  3. Boron carbide whiskers produced by vapor deposition

    Science.gov (United States)

    1965-01-01

    Boron carbide whiskers have an excellent combination of properties for use as a reinforcement material. They are produced by vaporizing boron carbide powder and condensing the vapors on a substrate. Certain catalysts promote the growth rate and size of the whiskers.

  4. Hot flow behavior of boron microalloyed steels

    International Nuclear Information System (INIS)

    Lopez-Chipres, E.; Mejia, I.; Maldonado, C.; Bedolla-Jacuinde, A.; El-Wahabi, M.; Cabrera, J.M.

    2008-01-01

    This research work studies the effect of boron contents on the hot flow behavior of boron microalloyed steels. For this purpose, uniaxial hot-compression tests were carried out in a low carbon steel microalloyed with four different amounts of boron over a wide range of temperatures (950, 1000, 1050 and 1100 deg. C) and constant true strain rates (10 -3 , 10 -2 and 10 -1 s -1 ). Experimental results revealed that both peak stress and peak strain tend to decrease as boron content increases, which indicates that boron additions have a solid solution softening effect. Likewise, the flow curves show a delaying effect on the kinetics of dynamic recrystallization (DRX) when increasing boron content. Deformed microstructures show a finer austenitic grain size in the steel with higher boron content (grain refinement effect). Results are discussed in terms of boron segregation towards austenitic grain boundaries during plastic deformation, which increases the movement of dislocations, enhances the grain boundary cohesion and modificates the grain boundary structure

  5. Compression and associated properties of boron carbide

    Science.gov (United States)

    Ciezak, Jennifer; Dandekar, Dattatraya

    2009-06-01

    The observed loss of shear strength of boron carbide around 22 GPa has been attributed to presence of amorphous material in the shock recovered, and statically indented and pressurized boron carbide. The present work presents a more direct association of the observed loss of shear strength in boron carbide under plane shock wave compression to amorphization in boron carbide under triaxial stress compression. This evidence is obtained from in-situ measurement of Raman, and infrared vibrational spectra of boron carbide confined in a Diamond Anvil Cell (DAC) under hydrostatic and non-hydrostatic pressures. X-ray-diffraction measurements do show a shift in the compression of boron carbide around 27 GPa. However, X-ray diffraction measurements indicate that the amorphization does not extend to micron scale, as there is no evidence of a loss of crystallinity in the recorded diffraction pattern of boron carbide to 47 GPa. Our work shows that shear plays a very dominant role in the stress-induced amorphization of boron carbide.

  6. Ultratough single crystal boron-doped diamond

    Science.gov (United States)

    Hemley, Russell J [Carnegie Inst. for Science, Washington, DC ; Mao, Ho-Kwang [Carnegie Inst. for Science, Washington, DC ; Yan, Chih-Shiue [Carnegie Inst. for Science, Washington, DC ; Liang, Qi [Carnegie Inst. for Science, Washington, DC

    2015-05-05

    The invention relates to a single crystal boron doped CVD diamond that has a toughness of at least about 22 MPa m.sup.1/2. The invention further relates to a method of manufacturing single crystal boron doped CVD diamond. The growth rate of the diamond can be from about 20-100 .mu.m/h.

  7. Spectral tailoring for boron Neutron capture therapy

    NARCIS (Netherlands)

    Nievaart, V.A.

    2007-01-01

    In several places in the world, such as Petten and Delft in the Netherlands, investigations are in progress in the fight against certain types of cancer with Boron Neutron Capture Therapy. The basic idea is very simple: boron is loaded only into the cancer cells, using a special drug, after which

  8. Fabrication of boron-phosphide neutron detectors

    International Nuclear Information System (INIS)

    Fitzsimmons, M.; Pynn, R.

    1997-01-01

    Boron phosphide is a potentially viable candidate for high neutron flux neutron detectors. The authors have explored chemical vapor deposition methods to produce such detectors and have not been able to produce good boron phosphide coatings on silicon carbide substrates. However, semi-conducting quality films have been produced. Further testing is required

  9. Possible toxicity of boron on sugar cane

    Energy Technology Data Exchange (ETDEWEB)

    Bravo C., M.

    Analyses of necrotic and green leaf tissues from sugar cane grown in the Tambo Valley (Arequipa, Peru) have shown that the boron concentration in necrotic tissue (average 657.7 ppm) is several times higher than that in the green tissue (average 55.7 ppm). This suggests that the necrosis may be due to boron toxicity.

  10. Unveiling the structure of polytetraruthenated nickel porphyrin by Raman spectroelectrochemistry.

    Science.gov (United States)

    Ferreira, Luís M C; Grasseschi, Daniel; Santos, Mauro S F; Martins, Paulo R; Gutz, Ivano G R; Ferreira, Ana Maria C; Araki, Koiti; Toma, Henrique E; Angnes, Lúcio

    2015-04-14

    The structure of polytetraruthenated nickel porphyrin was unveiled for the first time by electrochemistry, Raman spectroelectrochemistry, and a hydroxyl radical trapping assay. The electrocatalytic active material, precipitated on the electrode surface after successive cycling of [NiTPyP{Ru(bipy)2Cl}4](4+) species in strong aqueous alkaline solution (pH 13), was found to be a peroxo-bridged coordination polymer. The electropolymerization process involves hydroxyl radicals (as confirmed by the characteristic set of DMPO/(•)OH adduct EPR peaks) as reaction intermediates, electrocatalytically generated in the 0.80-1.10 V range, that induce the formation of Ni-O-O-Ni coordination polymers, as evidenced by Raman spectroelectrochemistry and molecular modeling studies. The film growth is halted above 1.10 V due to the formation of oxygen gas bubbles.

  11. Lipophilic manganese porphyrin crosses blood-brain barrier

    International Nuclear Information System (INIS)

    Nelson, J.A.; Cegnar, J.; Spence, A.M.; Richards, T.L.; Golden, R.N.; Muzi, M.

    1987-01-01

    Most reports on manganese porphyrins as MR imaging contrast agents have focused on a water-soluble compound, Mn-TPPS4. Phototherapy researchers have noted that lipophilic components of hematoporphyrin derivative sensitize normal brain tissue to light-stimulated photodestruction. This observation suggests that a lipophilic paramagnetic agent might be useful for brain contrast enhancement. The current experiments were designed to test the MR imaging effects of a lipid-soluble compound, Mn-mesoporphyrin. An intravenous injection of 0.05 μmoles/kg was administered to rats with a well-characterized astrocytic glioma implanted into the right cerebral hemisphere. MR imaging experiments performed at 2 T on a General Electric CSI-II system revealed T1 relaxation shortening in both normal brain and tumor. Delayed images at 24 hours revealed persistent selective contrast agent enhancement at the gross tumor site

  12. Respiratory Monitoring by Porphyrin Modified Quartz Crystal Microbalance Sensors

    Directory of Open Access Journals (Sweden)

    Seung-Woo Lee

    2011-01-01

    Full Text Available A respiratory monitoring system based on a quartz crystal microbalance (QCM sensor with a functional film was designed and investigated. Porphyrins 5,10,15,20-tetrakis-(4-sulfophenyl-21H,23H-porphine (TSPP and 5,10,15,20-tetrakis-(4-sulfophenyl-21H, 23H-porphine manganese (III chloride (MnTSPP used as sensitive elements were assembled with a poly(diallyldimethyl ammonium chloride (PDDA. Films were deposited on the QCM resonators using layer-by-layer method in order to develop the sensor. The developed system, in which the sensor response reflects lung movements, was able to track human respiration providing respiratory rate (RR and respiratory pattern (RP. The sensor system was tested on healthy volunteers to compare RPs and calculate RRs. The operation principle of the proposed system is based on the fast adsorption/desorption behavior of water originated from human breath into the sensor films deposited on the QCM electrode.

  13. FLUORESCENT DIAGNOSTICS OF MALIGNANT SKIN TUMORS WITH CHLORIN SERIES PHOTOSENSITIZERS

    Directory of Open Access Journals (Sweden)

    E. V. Yaroslavtseva-Isaeva

    2018-01-01

    Full Text Available The article shows possibilities in fluorescence imaging of malignant skin tumors with chlorin series photosensitizers (PS photolon and fotoditazin. The regularities of photosensitizer accumulation from the data of local fluorescence spectroscopy depending on the PS and its dose, the clinical picture and the histological form of the malignant skin neoplasm is investigated. It is shown that the level and selectivity of PS accumulation in the tumor focus depends on the PS dose. In studies on 10 patients with basal cell skin cancer after the introduction of fotoditazin at a dose less than 1 mg/kg, fluorescent contrast between tumor and healthy tissue varied between 1.3 and 9.5, the average was 2.8±0.3; for patients who had the administered fotoditazin dose of 1 mg/kg, fluorescent contrast was 2.9±0.4, varying from 1.4 to 5. In a study with 127 patients after the introduction of photolon in the dose of 0.7-1 mg/kg, the average value of the fluorescence intensity in relative units in the intact skin was 6.9±0.3 (min 4.6, max 12.2, at a dose of 1.1 to 1.4 mg/kg – 8.0±0.3 (min 4.6, max 12.5, at a dose of 1.5-2 mg/kg – 9.9±0.7 (min 5.7, max 20.3. It is also shown that fluorescence intensity of malignant neoplasm of the skin with the same dose of the photosensitizer depends on the neoplasm’s clinical and histological forms. So, 3 hours after the introduction of photolon at a dose of 1.3 mg/kg the average fluorescent contrast in the surface type of skin cancer was 2.7±0.5, in the nodal form – 2.3±0.2, in erosive-ulcerative form – 3.6±0.3. In patients with nodular form of squamous skin cancer after the introduction of photolon at a dose of 1.3 mg/kg fluorescent contrast was significantly higher (p<0.05 (average of 2.8±0.2 than in the nodular form of basal cell carcinoma after the introduction of photolon at the same dose (average of 2.1±0.2.

  14. Photodynamic activity of the boronated chlorin e6 amide in artificial and cellular membranes.

    Science.gov (United States)

    Antonenko, Yuri N; Kotova, Elena A; Omarova, Elena O; Rokitskaya, Tatyana I; Ol'shevskaya, Valentina A; Kalinin, Valery N; Nikitina, Roza G; Osipchuk, Julia S; Kaplan, Mikhail A; Ramonova, Alla A; Moisenovich, Mikhail M; Agapov, Igor I; Kirpichnikov, Mikhail P

    2014-03-01

    Photodynamic tumor-destroying activity of the boronated chlorin e6 derivative BACE (chlorin e6 13(1)-N-{2-[N-(1-carba-closo-dodecaboran-1-yl)methyl]aminoethyl}amide-15(2), 17(3)-dimethyl ester), previously described in Moisenovich et al. (2010) PLoS ONE 5(9) e12717, was shown here to be enormously higher than that of unsubstituted chlorin e6, being supported by the data on much higher photocytotoxicity of BACE in M-1 sarcoma cell culture. To validate membrane damaging effect as the basis of the enhanced tumoricidal activity, BACE was compared with unsubstituted chlorin e6 in the potency to photosensitize dye leakage from liposomes, transbilayer lipid flip-flop, inactivation of gramicidin A ionic channels in planar lipid membranes and erythrocyte hemolysis. In all the models comprising artificial and cellular membranes, the photodynamic effect of BACE exceeded that of chlorin e6. BACE substantially differed from chlorin e6 in the affinity to liposomes and erythrocytes, as monitored by fluorescence spectroscopy, flow cytometry and centrifugation. The results support the key role of membrane binding in the photodynamic effect of the boronated chlorin e6 amide. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Boron isotopic enrichment by displacement chromatography

    International Nuclear Information System (INIS)

    Mohapatra, K.K.; Bose, Arun

    2014-01-01

    10 B enriched boron is used in applications requiring high volumetric neutron absorption (absorption cross section- 3837 barn for thermal and 1 barn for 1 MeV fast neutron). It is used in fast breeder reactor (as control rod material), in neutron counter, in Boron Neutron Capture Therapy etc. Owing to very small separation factor, boron isotopic enrichment is a complex process requiring large number of separation stages. Heavy Water Board has ventured in industrial scale production of 10 B enriched boron using Exchange Distillation Process as well as Ion Displacement Chromatography Process. Ion Displacement Chromatography process is used in Boron Enrichment Plant at HWP, Manuguru. It is based on isotopic exchange between borate ions (B(OH) 4 - ) on anion exchange resin and boric acid passing through resin. The isotopic exchange takes place due to difference in zero point energy of 10 B and 11 B

  16. XPS analysis of boron doped heterofullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Schnyder, B.; Koetz, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muhr, H.J.; Nesper, R. [ETH Zurich, Zurich (Switzerland)

    1997-06-01

    Boron heterofullerenes were generated through arc-evaporation of doped graphite rods in a helium atmosphere. According to mass spectrometric analysis only mono-substituted fullerenes like C{sub 59}B, C{sub 69}B and higher homologues together with a large fraction of higher undoped fullerenes were extracted and enriched when pyridine was used as the solvent. XPS analysis of the extracts indicated the presence of two boron species with significantly different binding energies. One peak was assigned to borid acid. The second one corresponds to boron in the fullerene cage, which is mainly C{sub 59}B, according to the mass spectrum. This boron is in a somewhat higher oxidation state than that of ordinary boron-carbon compounds. The reported synthesis and extraction procedure opens a viable route for production of macroscopic amounts of these compounds. (author) 2 figs., 1 tab., 7 refs.

  17. Continuum modeling of boron nitride nanotubes

    International Nuclear Information System (INIS)

    Song, J; Wu, J; Hwang, K C; Huang, Y

    2008-01-01

    Boron nitride nanotubes display unique properties and have many potential applications. A finite-deformation shell theory is developed for boron nitride nanotubes directly from the interatomic potential to account for the effect of bending and curvature. Its constitutive relation accounts for the nonlinear, multi-body atomistic interactions, and therefore can model the important effect of tube chirality and radius. The theory is then used to determine whether a single-wall boron nitride nanotube can be modeled as a linear elastic isotropic shell. Instabilities of boron nitride nanotubes under different loadings (e.g., tension, compression, and torsion) are also studied. It is shown that the tension instability of boron nitride nanotubes is material instability, while the compression and torsion instabilities are structural instabilities.

  18. Stabilization of boron carbide via silicon doping.

    Science.gov (United States)

    Proctor, J E; Bhakhri, V; Hao, R; Prior, T J; Scheler, T; Gregoryanz, E; Chhowalla, M; Giulani, F

    2015-01-14

    Boron carbide is one of the lightest and hardest ceramics, but its applications are limited by its poor stability against a partial phase separation into separate boron and carbon. Phase separation is observed under high non-hydrostatic stress (both static and dynamic), resulting in amorphization. The phase separation is thought to occur in just one of the many naturally occurring polytypes in the material, and this raises the possibility of doping the boron carbide to eliminate this polytype. In this work, we have synthesized boron carbide doped with silicon. We have conducted a series of characterizations (transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and x-ray diffraction) on pure and silicon-doped boron carbide following static compression to 50 GPa non-hydrostatic pressure. We find that the level of amorphization under static non-hydrostatic pressure is drastically reduced by the silicon doping.

  19. Cell diversity and network dynamics in photosensitive human brain organoids.

    Science.gov (United States)

    Quadrato, Giorgia; Nguyen, Tuan; Macosko, Evan Z; Sherwood, John L; Min Yang, Sung; Berger, Daniel R; Maria, Natalie; Scholvin, Jorg; Goldman, Melissa; Kinney, Justin P; Boyden, Edward S; Lichtman, Jeff W; Williams, Ziv M; McCarroll, Steven A; Arlotta, Paola

    2017-05-04

    In vitro models of the developing brain such as three-dimensional brain organoids offer an unprecedented opportunity to study aspects of human brain development and disease. However, the cells generated within organoids and the extent to which they recapitulate the regional complexity, cellular diversity and circuit functionality of the brain remain undefined. Here we analyse gene expression in over 80,000 individual cells isolated from 31 human brain organoids. We find that organoids can generate a broad diversity of cells, which are related to endogenous classes, including cells from the cerebral cortex and the retina. Organoids could be developed over extended periods (more than 9 months), allowing for the establishment of relatively mature features, including the formation of dendritic spines and spontaneously active neuronal networks. Finally, neuronal activity within organoids could be controlled using light stimulation of photosensitive cells, which may offer a way to probe the functionality of human neuronal circuits using physiological sensory stimuli.

  20. Photosensitized Oxygenations of Hexamethylbenzene in Phase Contact Enhanced Microreactor

    International Nuclear Information System (INIS)

    Park, Chan Yi; Park, Jeong Hyeon; Lim Hyo Jin; Hwang, Geumsook; Park, Chan Pil

    2014-01-01

    Activated singlet oxygen ( 1 O 2 ) has successfully been utilized in production of various compounds including fragrances, pharmaceuticals, and fine chemicals. However, the traditional reaction required a prolonged reaction time due to the difficulty of introducing adequate light and oxygen into the solution. Low contact probability between four species of oxygen, photosensitizer, light, and reagent is an inherent drawback of the traditional photoreaction. Molecular diffusion distance is the most important factor in the heterogeneous reactions including gas-liquid, gassolid, liquid-solid, and immiscible liquid-liquid. Therefore, rates of reaction are closely depended on the distance. Microreactor has provided a distinct advantage in the short molecular diffusion distance due to the high surface-to-volume ratio driven by narrow fluidic channels

  1. Singlet oxygen-based electrosensing by molecular photosensitizers

    Science.gov (United States)

    Trashin, Stanislav; Rahemi, Vanoushe; Ramji, Karpagavalli; Neven, Liselotte; Gorun, Sergiu M.; de Wael, Karolien

    2017-07-01

    Enzyme-based electrochemical biosensors are an inspiration for the development of (bio)analytical techniques. However, the instability and reproducibility of the reactivity of enzymes, combined with the need for chemical reagents for sensing remain challenges for the construction of useful devices. Here we present a sensing strategy inspired by the advantages of enzymes and photoelectrochemical sensing, namely the integration of aerobic photocatalysis and electrochemical analysis. The photosensitizer, a bioinspired perfluorinated Zn phthalocyanine, generates singlet-oxygen from air under visible light illumination and oxidizes analytes, yielding electrochemically-detectable products while resisting the oxidizing species it produces. Compared with enzymatic detection methods, the proposed strategy uses air instead of internally added reactive reagents, features intrinsic baseline correction via on/off light switching and shows C-F bonds-type enhanced stability. It also affords selectivity imparted by the catalytic process and nano-level detection, such as 20 nM amoxicillin in μl sample volumes.

  2. Photosensitized Oxygenations of Hexamethylbenzene in Phase Contact Enhanced Microreactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chan Yi; Park, Jeong Hyeon; Lim Hyo Jin; Hwang, Geumsook; Park, Chan Pil [Chungnam National Univ., Daejeon (Korea, Republic of)

    2014-04-15

    Activated singlet oxygen ({sup 1}O{sub 2}) has successfully been utilized in production of various compounds including fragrances, pharmaceuticals, and fine chemicals. However, the traditional reaction required a prolonged reaction time due to the difficulty of introducing adequate light and oxygen into the solution. Low contact probability between four species of oxygen, photosensitizer, light, and reagent is an inherent drawback of the traditional photoreaction. Molecular diffusion distance is the most important factor in the heterogeneous reactions including gas-liquid, gassolid, liquid-solid, and immiscible liquid-liquid. Therefore, rates of reaction are closely depended on the distance. Microreactor has provided a distinct advantage in the short molecular diffusion distance due to the high surface-to-volume ratio driven by narrow fluidic channels.

  3. Combination of photosensitive elements for use in radiography

    International Nuclear Information System (INIS)

    Bollen, R.H.; Vandenabeele, H.

    1976-01-01

    A new and improved combination of photosensitive elements is proposed that can be used in radiography. The combination according to the invention is composed of an X-ray fluorescence intensifying screen and a photographic halide of silver containing a color coupler. The color coupler causes a negative silver image and a color image to be formed in the material. The fluorescent layer of the fluorescence screen contains a mixture of lanthanum oxychloride or lanthanum oxybromide activated with terbium or terbium and ytterbium. Detailed information about variants in the composition of the fluorescent substance, the grain sizes of the silver halides, variations of the color couplers and about the coating of the single layers is given. (UWI) [de

  4. Analysis of boron nitride by flame spectrometry methods

    International Nuclear Information System (INIS)

    Telegin, G.F.; Chapysheva, G.Ya.; Shilkina, N.N.

    1989-01-01

    A rapid method has been developed for determination of free and total boron contents as well as trace impurities in boron nitride by using autoclave sample decomposition followed by atomic emission and atomic absorption determination. The relative standard deviation is not greater than 0.03 in the determination of free boron 0.012 in the determination of total boron content

  5. Chemical vapor deposited boron carbide

    International Nuclear Information System (INIS)

    Mackinnon, I.D.R.; Smith, K.L.

    1987-01-01

    Detailed analytical electron microscope (AEM) studies of yellow whiskers produced by chemical vapor deposition (CVD) show that two basic types of whiskers are produced at low temperatures (between 1200 0 C and 1400 0 C) and low boron to carbon gas ratios. Both whisker types show planar microstructures such as twin planes and stacking faults oriented parallel to, or at a rhombohedral angle to, the growth direction. For both whisker types, the presence of droplet-like terminations containing both Si and Ni indicate that the growth process during CVD is via a vapor-liquid-solid (VLS) mechanisms

  6. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

    Full Text Available We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration.

  7. Boron Enrichment in Martian Clay

    Science.gov (United States)

    Nagashima, Kazuhide; Freeland, Stephen J.

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration. PMID:23762242

  8. Positron annihilation in boron nitride

    Directory of Open Access Journals (Sweden)

    N.Amrane

    2006-01-01

    Full Text Available Electron and positron charge densities are calculated as a function of position in the unit cell for boron nitride. Wave functions are derived from pseudopotential band structure calculations and the independent particle approximation (IPM, respectively, for electrons and positrons. It is observed that the positron density is maximum in the open interstices and is excluded not only from ion cores but also to a considerable degree from valence bonds. Electron-positron momentum densities are calculated for (001,110 planes. The results are used in order to analyse the positron effects in BN.

  9. Investigation of photodynamic therapy optimization for port wine stain using modulation of photosensitizer administration methods.

    Science.gov (United States)

    Wang, Ying; Zuo, Zhaohui; Liao, Xiaohua; Gu, Ying; Qiu, Haixia; Zeng, Jing

    2013-12-01

    To raise photosensitizer concentration level during the photodynamic therapy process, two new methods of photosensitizer administration were investigated. The first method involves the slow intravenous injection of photosensitizer throughout the first 15 min of irradiation, and the second method involves 30 min fomentation before photosensitizer injection and irradiation. The fluorescence spectra of port wine stain skin were monitored and the therapeutic effect correlated index was calculated with a previously published spectral algorithm. Thirty cases were divided into group A (slow injection of photosensitizer during the first 15 min), group B (fomentation), and group C (control group, traditional injection method), with 10 cases in each group. To analyze the effect of these two new methods, the change of therapeutic effect correlated index values of two photodynamic therapy sessions for each patient were calculated, and the photodynamic therapy outcome was compared. The results showed that the change of therapeutic effect correlated index in group A was slightly more remarkable than that in the control group. The change of therapeutic effect correlated index in group B was similar to that in the control group. Slow injection of photosensitizer during photodynamic therapy has a potential to increase photosensitizer concentration level during photodynamic therapy. However, fomentation before photodynamic therapy has no such potential. There is a need for new methods to be attempted.

  10. Induction of photosensitivity in sheep with Erodium moschatum (L. L'Hérit

    Directory of Open Access Journals (Sweden)

    J.C. Stroebel

    2002-07-01

    Full Text Available Erodium moschatum is an exotic weed in the southern and southwestern coastal areas of the Western Cape Province (WCP, South Africa. It has been suspected as the cause of photosensitivity in sheep. However, attempts to induce photosensitivity by dosing it to sheep have thus far been unsuccessful. During August 1999, 2 sheep suffering from severe photosensitivity were presented for clinical examination to the Western Cape Provincial Veterinary Laboratory (WCPVL. One sheep was sacrificed for autopsy. Except for skin lesions associated with photosensitivity, no icterus or other lesions were present. Histopathological examination of affected skin revealed epidermal necrosis while the liver had no microscopic lesions. It was therefore concluded that the sheep might have been suffering from primary photosensitivity. The farmfrom which the sheep came, situated in the Malmesbury district, WCP, was visited to determine the source of the photodynamic agent. The flock from which the sheep originated had been grazing in a camp where E. moschatum was growing abundantly and had been heavily grazed. Some remaining Erodium in the camp was collected, pulped and dosed over a period of 7 days to an adult sheep. Another sheep was dosed simultaneously with Erodium growing on the premises of the WCPVL. Both sheep developed mild photosensitivity, which was confirmed by histopathological examination of skin biopsies. It was concluded that E. moschatum can induce photosensitivity (probably the primary type in sheep if ingested in large quantities.

  11. Boron nutrition and yield of alfalfa cultivar crioula in relation to boron supply

    Directory of Open Access Journals (Sweden)

    Santos Anacleto Ranulfo dos

    2004-01-01

    Full Text Available Alfalfa cultivar Crioula (Medicago sativa cv. Crioula is grown in South Brazil and only a few studies on the plants' boron requirement are available. A greenhouse experiment was carried out with alfalfa to measure boron acquisition, production and distribution in the plant; data on critical level and production potentials were recorded. Plants were grown in ground quartz added with 1 L of solution, with the following boron rates: 0, 0.0625, 0.125, 0.25, 0.50, 1.00, and 2.00 mg L-1. Plants were harvested at 46 days of growth. Forage dry mass was increased by boron supply and dry matter accumulation was considerably low in control. Boron concentration in the leaves was higher than in the stems or roots. Boron utilization from the external solution reached 90% at 0.0625 mg L-1 and sharply decreased with further increasing boron rates. Boron concentration and content in the leaves and in plant tops were at maximum when applied boron was between 1.5 and 1.6 mg L-1. Critical levels of boron in plant were 61 mg kg-1 in the leaves and 39 mg kg-1 in plant tops for this cultivar of alfalfa.

  12. Experimental boron neutron capture therapy for melanoma: Systemic delivery of boron to melanotic and amelanotic melanoma

    International Nuclear Information System (INIS)

    Coderre, J.A.; Glass, J.D.; Micca, P.; Greenberg, D.; Packer, S.

    1990-01-01

    The boron-containing melanin precursor analogue p-boronophenylalanine (BPA) has previously been shown to selectively deliver boron to pigmented murine melanomas when administered in a single intragastric dose. If boron neutron capture therapy is to become a clinically useful method of radiation therapy for human malignant melanoma, the boron carrier must be capable of delivering useful amounts of boron to remote tumor sites (metastases) and to poorly pigmented melanomas. The authors have now determined the ability of BPA to accumulate in several nonpigmented melanoma models including human melanoma xenografts in nude mice. The absolute amount of boron in the nonpigmented melanomas was about 50% of the observed in the pigmented counterparts but was still selectively concentrated in the tumor relative to normal tissues in amounts sufficient for effective neutron capture therapy. Single intragastric doses of BPA resulted in selective localization of boron in the amelanotic Greene melanoma carried in the anterior chamber of the rabbit eye and in a pigmented murine melanoma growing in the lungs. The ratio of the boron concentration in these tumors to the boron concentration in the immediately adjacent normal tissue was in the range of 3:1 to 4:1. These distribution studies support the proposal that boron neutron capture therapy may be useful as a regional therapy for malignant melanoma

  13. Study of ceramic mixed boron element as a neutron shielding

    International Nuclear Information System (INIS)

    Ismail Mustapha; Mohd Reusmaazran Yusof; Md Fakarudin Ab Rahman; Nor Paiza Mohamad Hasan; Samihah Mustaffha; Yusof Abdullah; Mohamad Rabaie Shari; Airwan Affandi Mahmood; Nurliyana Abdullah; Hearie Hassan

    2012-01-01

    Shielding upon radiation should not be underestimated as it can causes hazard to health. Precautions on the released of radioactive materials should be well concerned and considered. Therefore, the combination of ceramic and boron make them very useful for shielding purpose in areas of low and intermediate neutron. A six grades of ceramic tile have been produced namely IMN05 - 5 % boron, IMN06 - 6 % boron, IMN07 - 7 % boron, IMN08 - 8 % boron, IMN09 - 9 % boron, IMN10 - 10 % boron from mixing, press and sintered process. Boron is a material that capable of absorbing and capturing neutron, so that neutron and gamma test were conducted to analyze the effectiveness of boron material in combination with ceramic as shielding. From the finding, percent reduction number of count per minute shows the ceramic tiles are capable to capture neutron. Apart from all the percentage of boron used, 10 % is the most effective shields since the percent reduction indicating greater neutron captured increased. (author)

  14. Analysis of Boron Distribution in Steel using Neutron at HANARO

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Eun-Joo; Seong, Baek-Seok; Kim, Hark-Rho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2007-07-01

    Boron is very useful element in steels to improve the mechanical properties. In steel matrix, boron exist several types such as solute, segregation in grain boundary and many kinds of precipitate, which influence the properties of the steel. But, detecting of boron using X-ray or ion-beam is not easy because boron is very light atom than iron. However neutron gives the clear image of boron distribution from the particle tracking autoradiography (PTA) method. The PTA method of boron uses the phenomenon that boron irradiated by neutron emits Liion and alpha particle. Boron distribution can be obtained by observing the traces of the emitted Li-ion and alpha particle. At HANARO, the study for observing of boron distribution has been performed several years ago. Recently, the experimental techniques were improved for the reactor power of 30 MW. In this paper, improved experimental techniques were described and some results for boron added low-carbon steel plate were introduced.

  15. A Study of the Operation of Especially Designed Photosensitive Gaseous Detectors at Cryogenic Temperatures

    CERN Document Server

    Periale, L; Lund-Jensen, B; Pavlopoulos, P; Peskov, Vladimir; Picchi, P; Pietropaolo, F

    2006-01-01

    In some experiments and applications there is need for large-area photosensitive detectors to operate at cryogenic temperatures. Nowadays, vacuum PMs are usually used for this purpose. We have developed special designs of planar photosensitive gaseous detectors able to operate at cryogenic temperatures. Such detectors are much cheaper PMs and are almost insensitive to magnetic fields. Results of systematic measurements of their quantum efficiencies, the maximum achievable gains and long-term stabilities will be presented. The successful operation of these detectors open realistic possibilities in replacing PMs by photosensitive gaseous detectors in some applications dealing with cryogenic liquids; for example in experiments using noble liquid TPCs or noble liquid scintillating calorimeters.

  16. Studies on Separation Process and Production Technology of Boron Isotope

    OpenAIRE

    LI Jian-ping

    2014-01-01

    The boron isotopes separation test was performed by chemical exchange reaction in the benzene ether -three boron fluoride system, which resulted to the boron isotopic enrichment of -10 in the liquid phase, the boron isotopic enrichment of -11 in the gas phase. After then, boron isotope separation trial production has been finished. In this process, the exchange column and complex tower normal operating parameters and the complex tower technology have been obtained, the problems of material di...

  17. Composite boron nitride neutron detectors

    Science.gov (United States)

    Roth, M.; Mojaev, E.; Khakhan, O.; Fleider, A.; Dul`kin, E.; Schieber, M.

    2014-09-01

    Single phase polycrystalline hexagonal boron nitride (BN) or mixed with boron carbide (BxC) embedded in an insulating polymeric matrix acting as a binder and forming a composite material as well as pure submicron size polycrystalline BN has been tested as a thermal neutron converter in a multilayer thermal neutron detector design. Metal sheet electrodes were covered with 20-50 μm thick layers of composite materials and assembled in a multi-layer sandwich configuration. High voltage was applied to the metal electrodes to create an interspacing electric field. The spacing volume could be filled with air, nitrogen or argon. Thermal neutrons were captured in converter layers due to the presence of the 10B isotope. The resulting nuclear reaction produced α-particles and 7Li ions which ionized the gas in the spacing volume. Electron-ion pairs were collected by the field to create an electrical signal proportional to the intensity of the neutron source. The detection efficiency of the multilayer neutron detectors is found to increase with the number of active converter layers. Pixel structures of such neutron detectors necessary for imaging applications and incorporation of internal moderator materials for field measurements of fast neutron flux intensities are discussed as well.

  18. Boron-Loaded Silicone Rubber Scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Z.W.; Maya, L.; Brown, G.M.; Sloop, F.V.Jr

    2003-05-12

    Silicone rubber received attention as an alternative to polyvinyltoluene in applications in which the scintillator is exposed to high doses because of the increased resistance of the rubber to the formation of blue-absorbing color centers. Work by Bowen, et al., and Harmon, et al., demonstrated their properties under gamma/x-ray irradiation, and Bell, et al. have shown their response to thermal neutrons. This last work, however, provided an example of a silicone in which both the boron and the scintillator were contained in the rubber as solutes, a formulation which led to the precipitation of solids and sublimation of the boron component. In the present work we describe a scintillator in which the boron is chemically bonded to the siloxane and so avoids the problem of precipitation and loss of boron to sublimation. Material containing up to 18% boron, by weight, was prepared, mounted on photomultipliers, and exposed to both neutron and gamma fluxes. Pulse height spectra showing the neutron and photon response were obtained, and although the light output was found to be much poorer than from samples in which boron was dissolved, the higher boron concentrations enabled essentially 100% neutron absorption in only a few millimeters' thickness of rubber.

  19. Density separation of boron particles. Final report

    International Nuclear Information System (INIS)

    Smith, R.M.

    1980-04-01

    A density distribution much broader than expected was observed in lots of natural boron powder supplied by two different sources. The material in both lots was found to have a rhombohedral crystal structure, and the only other parameters which seemed to account for such a distribution were impurities within the crystal structure and varying isotopic ratios. A separation technique was established to isolate boron particles in narrow densty ranges. The isolated fractions were subsequently analyzed for B 10 and total boron content in an effort to determine whether selective isotopic enrichment and nonhomogeneous impurity distribution were the causes for the broad density distribution of the boron powders. It was found that although the B 10 content remained nearly constant around 18%, the total boron content varied from 37.5 to 98.7%. One of the lots also was found to contain an apparently high level of alpha rhombohedral boron which broadened the density distribution considerably. During this work, a capability for removing boron particles containing gross amounts of impurities and, thereby, improving the overall purity of the remaining material was developed. In addition, the separation technique used in this study apparently isolated particles with alpha and beta rhombohedral crystal structures, although the only supporting evidence is density data

  20. Noncovalent functionalization of carbon nanotubes with porphyrins: meso-tetraphenylporphine and its transition metal complexes.

    Science.gov (United States)

    Basiuk, Elena V; Basiuk, Vladimir A; Santiago, Patricia; Puente-Lee, Iván

    2007-01-01

    Noncovalent functionalization of carbon nanotubes with meso-tetraphenylporphine (H2TPP) and its metal(II) complexes NiTPP and CoTPP was studied by means of different experimental techniques and theoretical calculations. As follows from the experimental adsorption curves, free H2TPP ligand exhibits the strongest adsorption of three porphyrins tested, followed by CoTPP and NiTPP. At the highest porphyrin concentrations studied, the adsorption at multi-walled carbon nanotubes was about 2% (by weight) for H2TPP, 1% for CoTPP, and 0.5% for NiTPP. Transmission electron microscopy observations revealed carbon nanotubes with a variable degree of surface coverage with porphyrin molecules. According to scanning electron microscopy, the nanotubes glue together rather than debundle; apparently, a large porphyrin excess resulting in polymolecular adsorption is essential for exfoliation/debundling of the nanotube ropes. The nanotube/porphyrins hybrids were studied by infrared and Raman spectroscopy, as well as by scanning tunneling microscopy. Electronic structure calculations were performed at the B3LYP/LANL2MB theoretical level with the unsubstituted porphine (H2P) and its Co(II) complex, on one hand, and open-end armchair (5,5) (ANT) and zigzag (8,0) (ZNT) SWNT models, on the other hand. The interaction of H2P with ANT was found to be by 3.9 kcal mol(-1) stronger than that of CoP. At the same time, CoP+ZNT complex is more stable by 42.7 kcal mol(-1) as compared to H2P+ZNT According to these calculated results, the free porphyrins interact less selectively with zigzag and armchair (i.e., semiconducting and metallic) nanotubes, whereas the difference becomes very large for the metal porphyrins. HOMO-LUMO structure, electrostatic potential and spin density distribution for the paramagnetic cobalt(II) complexes were analyzed.

  1. Fluorescence spectroscopic studies on substituted porphyrins in homogeneous solvents and cationic micellar medium

    International Nuclear Information System (INIS)

    Phukan, Smritakshi; Mishra, Bhupendra; Chandra Shekar, K.P.; Kumar, Anil; Kumar, Dalip; Mitra, Sivaprasad

    2013-01-01

    Steady state and time-resolved fluorescence properties of porphyrin appended 1,3,4-oxadiazoles and thiazoles were described in homogeneous medium as well as in presence of cationic surfactant cetyltrimethylammonium bromide (CTAB). The electron withdrawing substituent on the porphyrin moiety in both the cases make a donor–spacer–acceptor type of intramolecular photoinduced electron transfer (PET) system resulting substantial quenching in porphyrin fluorescence due to partial energy migration towards the acceptor in the excited state. The increase in fluorescence yield as well as appreciable difference in fluorescence decay behavior in aqueous buffer solution of pH 4.2 from that in chloroform solution is believed due to partial protonation of the porphyrin ring. All the investigated systems show preferential binding into the interfacial region of the micellar sub-domain with varying degree of penetration depending on the nature of the substituent. Almost 2–4 fold increase in fluorescence yield for the probes is explained on the basis of restricted flexibility and corresponding decrease in total nonradiative rate inside the micellar interface layer. - Highlights: ► Synthesis and detail fluorescence studies of a series of porphyrin appended 1,3,4-oxadiazoles and thiazoles. ► Comparison of homogeneous solvent study with that in CTAB. ► Substantial porphyrin fluorescence quenching in donor–spacer–acceptor type system. ► Preferential binding of the substituted porphyrins in micellar sub-domain. ► Appreciable increase in fluorescence yield in micellar interface layer is due to decrease in total nonradiative rate.

  2. Proceedings of workshop on 'Boron Chemistry and Boron Neutron Capture Therapy'

    International Nuclear Information System (INIS)

    Kitaoka, Y.

    1991-07-01

    This volume contains the proceedings of the 3rd Workshop on 'the Boron Chemistry and Boron Neutron Capture Therapy' held on February 12, in 1991. In this workshop, our attention was focused on the chemical nature of boron compounds and the boron neutron capture therapy (BNCT). First, clinical experiences of BNCT in KURRI in 1990 and 1991 were reported (Chap. 3). The feasibility of the gadolinium neutron capture therapy for brain tumors was discussed (Chap. 4). In the chemical field, a rapid spectrophotometric determination of trace amounts of borons in biological samples is described (Chap. 5). The chemical behaviours of p-boronophenylalanine and its analogs in aqueous solutions were investigated by a paper electrophoresis and infrared spectroscopy (Chap. 6). On the molecular design and synthesis of new boron carriers for BNCT, several new synthetic methods for B-10 containing nucleoside derivatives were shown (Chap. 7). (author)

  3. Electrical and thermal conductivities of the graphene, boron nitride and silicon boron honeycomb monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, Hamze, E-mail: hamze.mousavi@gmail.com [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Khodadadi, Jabbar [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Moradi Kurdestany, Jamshid [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65201 (United States); Yarmohammadi, Zahra [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of)

    2016-11-25

    Density of states, electrical and thermal conductivities of electrons in graphene, boron nitride and silicon boron single sheets are studied within the tight-binding Hamiltonian model and Green's function formalism, based on the linear response theory. The results show that while boron nitride keeps significantly the lowest amounts overall with an interval of zero value in low temperatures, due to its insulating nature, graphene exhibits the most electrical and thermal conductivities, slightly higher than silicon boron except for low temperature region where the latter surpasses, owing to its metallic character. This work might make ideas for creating new electronic devices based on honeycomb nanostructures. - Highlights: • Electronic properties of graphene, silicon boron, and boron nitride planes are compared. • Tight-binding Hamiltonian model and Green's function formalism are implemented. • This work might make ideas for creating new electronic devices based on honeycomb nanostructures.

  4. The determination of boron and carbon in reactor grade boron carbide

    International Nuclear Information System (INIS)

    Crossley, D.; Wood, A.J.; McInnes, C.A.J.; Jones, I.G.

    1978-09-01

    The sealed tube method of dissolution at high temperature and pressure has been successfully applied in the analysis of reactor grade boron carbide for the determination of boron. A 50 mg sample of boron carbide is completely dissolved by heating with concentrated nitric acid in a sealed tube at 300 0 C. The boron content of the resultant sample solution is determined by the mannitol potentiometric titration method. The precision of the method for the determination of 2.5 mg of boron using the Harwell automatic potentiometric titrator is 0.2% (coefficient of variation). The carbon content of a boron carbide sample is determined by combustion of the sample at 1050 0 C in a stream of oxygen using vanadium pentoxide to ensure the complete oxidation of the sample. The carbon dioxide produced from the sample is measured manometrically and the precision of the method for the determination of 4 mg of carbon is 0.4% (coefficient of variation). (author)

  5. Quantitative boron detection by neutron transmission method

    International Nuclear Information System (INIS)

    Okka, M.; Genceli, M.; Eren, E.; Bayulken, A.

    2008-01-01

    //Quantitative boron detection is mainly performed by chemical methods like colorimetric titration. High neutron absorption cross section of natural boron makes attractive its detection by absorption measurements. This work is an extension of earlier investigations where neutron radiography technique was used for boron detection. In the present investigation, the neutron absorption rate of boron containing solutions is the way to measure quantitatively the boron content of the solutions. The investigation was carried out in Istanbul TRIGA Mark-II reactor. In the end of the experiments, it was observed that even |ppw| grade boron in aqueous solution can be easily detected. The use of this method is certainly very useful for boron utilizing industries like glass and steel industries.The major disadvantage of the method is the obligation to use always aqueous solutions to be able to detect homogeneously the boron content. Then, steel or glass samples have to be put first in an appropriate solution form. The irradiation of steel samples can give the distribution of boron by the help of a imaging and this suggested method will give its quantitative measurement. The superiority of this method are its quick response time and its accuracy. To test this accuracy, a supposed unknown , solution of boric acid is irradiated and then calculated by the help of the calibration curve. The measured value of boric acid was 0.89 mg and the calculated value was found to be 0.98 mg which gives an accuracy of 10 %. It was also seen that the method is more accurate for low concentration. (authors)

  6. Effect of boron concentration on physicochemical properties of boron-doped carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Keru, Godfrey; Ndungu, Patrick G.; Nyamori, Vincent O., E-mail: nyamori@ukzn.ac.za

    2015-03-01

    Boron-doped carbon nanotubes (B-CNTs) were synthesized using chemical vapour deposition (CVD) floating catalyst method. Toluene was used as the carbon source, triphenylborane as boron as well as the carbon source while ferrocene was used as the catalyst. The amount of triphenylborane used was varied in a solution of toluene and ferrocene. Ferrocene was kept constant at 2.5 wt.%. while a maximum temperature of 900 °C was used for the synthesis of the shaped carbon nanomaterial (SCNMs). SCNMs obtained were characterized by the use of transmission electron microscope (TEM), scanning electron microscope (SEM), high resolution-electron microscope, electron dispersive X-ay spectroscopy (EDX), Raman spectroscopy, inductively coupled plasma-optical emission spectroscopy (ICP-OES), vibrating sample magnetometer (VSM), nitrogen adsorption at 77 K, and inverse gas chromatography. TEM and SEM analysis confirmed SCNMs obtained were a mixture of B-CNTs and carbon nanofibres (B-CNF). EDX and ICP-OES results showed that boron was successively incorporated into the carbon hexagonal network of CNTs and its concentration was dependent on the amount of triphenylborane used. From the VSM results, the boron doping within the CNTs introduced ferromagnetic properties, and as the percentage of boron increased the magnetic coactivity and squareness changed. In addition, boron doping changed the conductivity and the surface energy among other physicochemical properties of B-CNTs. - Highlights: • Boron-doping of carbon nanotubes (CNTs) changes their physiochemical properties. • Amount of boron-doping was dependent on the wt.% of boron precursor used. • Boron-doping changed CNTs surfaces and the distribution of dispersive energy sites. • Boron-doping affected the conductivity and ferromagnetic properties. • Increased boron-doping results in a more favourable interaction with polar probes.

  7. Boron Isotope Fractionation in Bell Pepper

    OpenAIRE

    Geilert, Sonja; Vogl, Jochen; Rosner, Martin; Voerkelius, Susanne; Eichert, Thomas

    2015-01-01

    Various plant compartments of a single bell pepper plant were studied to verify the variability of boron isotope composition in plants and to identify possible intra-plant isotope fractionation. Boron mass fractions varied from 9.8 mg/kg in the fruits to 70.0 mg/kg in the leaves. Boron (B) isotope ratios reported as δ11B ranged from -11.0‰ to +16.0‰ (U ≤ 1.9‰, k=2) and showed a distinct trend to heavier δ11B values the higher the plant compartments were located in the plant. A fractionatio...

  8. Study on plasma sprayed boron carbide coating

    Science.gov (United States)

    Zeng, Yi; Lee, Soo W.; Ding, Chuanxian

    2002-03-01

    The microstructure, phase composition, and mechanical properties of boron carbide coatings formed by atmospheric plasma spraying (APS) are studied in the present work. The boron carbide coating with high microhardness and low porosity could be produced by APS. The decomposition of boron carbide powder during the plasma spray process would result in the formation of the BxC phase and an increase of the carbon phase, which is confirmed by transmission electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction results.

  9. Porphyrin Based Near Infrared-Absorbing Materials for Organic Photovoltaics

    Science.gov (United States)

    Zhong, Qiwen

    photosynthesis. Photosynthesis uses light from the sun to drive a series of chemical reactions. Most natural photosynthetic systems utilize chlorophylls to absorb light energy and carry out photochemical charge separation that stores energy in the form of chemical bonds. The sun produces a broad spectrum of light output that ranges from gamma rays to radio waves. The entire visible range of light (400-700 nm) and some wavelengths in the NIR (700-1000 nm), are highly active in driving photosynthesis. Although the most familiar chlorophyll-containing organisms, such as plants, algae and cyanobacteria, cannot use light longer than 700 nm, anoxygenic bacterium containing bacteriochlorophylls can use the NIR part of the solar spectrum. No organism is known to utilize light of wavelength longer than about 1000 nm for photosynthesis. NIR light has a very low-energy content in each photon, so that large numbers of these low-energy photons would have to be used to drive the chemical reactions of photosynthesis. This is thermodynamically possible but would require a fundamentally different molecular mechanism that is more akin to a heat engine than to photochemistry. Early work on developing light absorbing materials for OPVs was inspired by photosynthesis in which light is absorbed by chlorophyll. Structurally related to chlorophyll is the porphyrin family, which has accordingly drawn much interest as the potential light absorbing component in OPV applications. In this dissertation, the design and detail studies of several porphyrin-based NIR absorbing materials, including pi--extended perylenyl porphryins and pyrazole-containing carbaporphyrins, as well as porphyrin modified single-walled carbon nanotube hybrids, will be presented, dedicating efforts to develop novel and application-oriented materials for efficient utilization of sustainable solar energy.

  10. Characterization of boron tolerant bacteria isolated from a fly ash dumping site for bacterial boron remediation.

    Science.gov (United States)

    Edward Raja, Chellaiah; Omine, Kiyoshi

    2013-08-01

    Boron is an essential micronutrient for plants, but can above certain concentrations be toxic to living organisms. A major environmental concern is the removal of boron from contaminated water and fly ash. For this purpose, the samples were collected from a fly ash dumping site, Nagasaki prefecture, Japan. The chemical characteristics and heavy metal concentration of the samples were performed by X-ray fluorescent analysis and leaching test. For bacterial analysis, samples were collected in sterile plastic sheets and isolation was carried out by serial dilution method. The boron tolerant isolates that showed values of maximum inhibitory concentration toward boron ranging from 100 to 260 mM level were screened. Based on 16S rRNA sequencing and phylogenetic analysis, the isolates were most closely related to the genera Bacillus, Lysinibacillus, Microbacterium and Ralstonia. The boron tolerance of these strains was also associated with resistant to several heavy metals, such as As (III), Cr (VI), Cd, Cu, Pb, Ni, Se (III) and Zn. Indeed, these strains were arsenic oxidizing bacteria confirmed by silver nitrate test. These strains exhibited their salt resistances ranging from 4 to 15 % were determined in Trypticase soy agar medium. The boron tolerant strains were capable of removing 0.1-2.0 and 2.7-3.7 mg l(-1) boron from the medium and fly ash at 168 h. Thus, we have successfully identified the boron tolerant and removal bacteria from a fly ash dumping site for boron remediation.

  11. Fluorescence emission analysis of photodynamic therapy photosensitizer as a monitoring biomarker

    Science.gov (United States)

    Fanjul-Vélez, F.; Rodríguez-Colmenares, M. A.; Arce-Diego, J. L.

    2017-07-01

    Photodynamic Therapy is a selective optical tumor destruction technique with practically no secondary effects. Monitoring by fluorescence photosensitizer emission is essential for an adequate treatment dosimetry, which avoids recurrence.

  12. Riboflavin and chlorophyll as photosensitizers in electroformed giant unilamellar vesicles as food models

    DEFF Research Database (Denmark)

    Wang, Hui Jing; Liang, Ran; du, Hui Hui

    2017-01-01

    for hydrophilic riboflavin, while lipophilic chlorophyll a initiated GUV budding and subsequent disintegration under light irradiation, indicating that lipophilic photosensitizers are the more important in such structured lipids. Lipophilic β-carotene provided protection against oxidative damage induced...

  13. Effectiveness of partially soluble photosensitizer in photodynamic microbiological inactivation: a curcumin example

    Science.gov (United States)

    Pratavieira, Sebastião.; Matroodi, Fatima; Pinto-Júnior, Fabio Francisco; Rastelli, Alessandra Nara Souza; Bagnato, Vanderlei S.; Guimarães, Francisco E. G.

    2017-07-01

    We show that partial solubility of a photosensitizer is not necessarily a bad property when dealing with microbiological control. The presence of curcumin aggregates in solution may present advantages with respect the photoand chemical stability.

  14. White matter microstructural changes of thalamocortical networks in photosensitivity and idiopathic generalized epilepsy

    DEFF Research Database (Denmark)

    Groppa, Sergiu; Moeller, Friederike; Siebner, Hartwig

    2012-01-01

    Photosensitivity or photoparoxysmal response (PPR) is an electroencephalography trait that is highly associated with idiopathic generalized epilepsies (IGEs) and characterized by changes in cortical excitability in response to photic stimulation. Studying functional and structural changes of PPR ...

  15. Raman and fluorescence microscopy to study the internalization and dissolution of photosensitizer nanoparticles into living cells

    Science.gov (United States)

    Scalfi-Happ, Claudia; Steiner, Rudolf; Wittig, Rainer; Graefe, Susanna; Ryabova, Anastasia; Loschenov, Victor

    2015-07-01

    In this present study we applied Raman and fluorescence microscopy to investigate the internalisation, cellular distribution and effects on cell metabolism of photosensitizer nanoparticles for photodynamic therapy in fibroblasts and macrophages.

  16. Synthesis, characterization, and reactivities of manganese(V)-oxo porphyrin complexes.

    Science.gov (United States)

    Song, Woon Ju; Seo, Mi Sook; George, Serena Debeer; Ohta, Takehiro; Song, Rita; Kang, Min-Jung; Tosha, Takehiko; Kitagawa, Teizo; Solomon, Edward I; Nam, Wonwoo

    2007-02-07

    The reactions of manganese(III) porphyrin complexes with terminal oxidants, such as m-chloroperbenzoic acid, iodosylarenes, and H(2)O(2), produced high-valent manganese(V)-oxo porphyrins in the presence of base in organic solvents at room temperature. The manganese(V)-oxo porphyrins have been characterized with various spectroscopic techniques, including UV-vis, EPR, 1H and 19F NMR, resonance Raman, and X-ray absorption spectroscopy. The combined spectroscopic results indicate that the manganese(V)-oxo porphyrins are diamagnetic low-spin (S = 0) species with a longer, weaker Mn-O bond than in previously reported Mn(V)-oxo complexes of non-porphyrin ligands. This is indicative of double-bond character between the manganese(V) ion and the oxygen atom and may be attributed to the presence of a trans axial ligand. The [(Porp)Mn(V)=O](+) species are stable in the presence of base at room temperature. The stability of the intermediates is dependent on base concentration. In the absence of base, (Porp)Mn(IV)=O is generated instead of the [(Porp)Mn(V)=O](+) species. The stability of the [(Porp)Mn(V)=O](+) species also depends on the electronic nature of the porphyrin ligands: [(Porp)Mn(V)=O](+) complexes bearing electron-deficient porphyrin ligands are more stable than those bearing electron-rich porphyrins. Reactivity studies of manganese(V)-oxo porphyrins revealed that the intermediates are capable of oxygenating PPh(3) and thioanisoles, but not olefins and alkanes at room temperature. These results indicate that the oxidizing power of [(Porp)Mn(V)=O](+) is low in the presence of base. However, when the [(Porp)Mn(V)=O](+) complexes were associated with iodosylbenzene in the presence of olefins and alkanes, high yields of oxygenated products were obtained in the catalytic olefin epoxidation and alkane hydroxylation reactions. Mechanistic aspects, such as oxygen exchange between [(Porp)Mn(V)=16O](+) and H(2)(18)O, are also discussed.

  17. Photosensitive Layer-by-Layer Assemblies Containing Azobenzene Groups: Synthesis and Biomedical Applications

    OpenAIRE

    Uichi Akiba; Daichi Minaki; Jun-ichi Anzai

    2017-01-01

    This review provides an overview of the syntheses of photosensitive layer-by-layer (LbL) films and microcapsules modified with azobenzene derivatives and their biomedical applications. Photosensitive LbL films and microcapsules can be prepared by alternate deposition of azobenzene-bearing polymers and counter polymers on the surface of flat substrates and microparticles, respectively. Azobenzene residues in the films and microcapsules exhibit trans-to-cis photoisomerization under UV light, wh...

  18. LED Light Source for in vitro Study of Photosensitizing Agents for Photodynamic Therapy

    OpenAIRE

    N.Y. Shilyagina; V.I. Plekhanov; I.V. Shkunov; P.А. Shilyagin; L.V. Dubasova; А.А. Brilkina; Е.А. Sokolova; I.V. Turchin; I.V. Balalaeva

    2014-01-01

    The aim of the investigation was to develop a LED light source providing a homogeneous light distribution in 96-well plates and allowing an independent irradiation of individual wells, as well as its experimental testing in in vitro study of photosensitizers for photodynamic therapy. Materials and Methods. The experiments were carried out on human cell lines of epidermoid carcinoma А-431 and human bladder carcinoma Т24. Two photosensitizers for fluorescence diagnostics and photodynamic th...

  19. Natural Porphyrins Accelerating the Phototransformation of Benzo[a]pyrene in Water.

    Science.gov (United States)

    Luo, Lijuan; Xiao, Zhengyu; Chen, Baowei; Cai, Fengshan; Fang, Ling; Lin, Li; Luan, Tiangang

    2018-02-21

    Phototransformation is one of the most important transformation pathways of organic contaminants in the water environment. However, how active compounds enable and accelerate the phototransformation of organic pollutants remains to be elucidated. In this study, the phototransformation of benzo[a]pyrene (BaP, the first class "human carcinogens") by various natural porphyrins under solar irradiation was investigated, including chlorophyll a, sodium copper chlorophyllin, hematin, cobalamin and pheophorbide a. Transformation efficiency of BaP varied considerably with chemical stabilities of the porphyrins. Porphyrins with a lower stability displayed higher BaP transformation efficiencies. BaP transformation had a significant positive correlation with the production of singlet oxygen. Identical phototransformation products of BaP were observed for all investigated porphyrins, and the main products were identified as BaP-quinones, including BaP-1,6-dione, BaP-3,6-dione and BaP-6,12-dione. The mechanism of natural porphyrins accelerating the BaP phototransformation in water was proposed to proceed via the photocatalytic generation of singlet oxygen resulting in the transformation of BaP to quinones.

  20. Synthesis and characterization of a novel series of meso (nitrophenyl and meso (carboxyphenyl substituted porphyrins

    Directory of Open Access Journals (Sweden)

    Schiavon Marco A.

    2000-01-01

    Full Text Available The anionic 5,10,15-tris(4-carboxyphenyl, 20-mono(2-nitrophenyl porphyrin (1, 5,10(or 15-bis(4-carboxyphenyl, 15(or 10,20-bis(2-nitrophenylporphyrin (2 and 5-mono(4-carboxyphenyl, 10,15,20-tris(2-nitrophenylporphyrin (3 were sinthesized directly by reaction of pyrrole with substituted benzaldehydes in nitrobenzene/propionic acid media. The benzaldehydes molar ratio was controlled to optimize the synthesis and purification of the desired porphyrins. This new series of porphyrins was characterised by TLC, mass spectrometry (FAB MS, ¹H NMR, UV/Vis, IR and electrochemistry. 5,10,15,20-Tetrakis(4-carboxyphenylporphyrin (4 and 5,10,15,20-Tetrakis(2-nitrophenylporphyrin (5 were also characterised for comparative purposes, completing the series The electrochemical reduction was investigated for the free base and corresponding iron(III porphyrins on glassy carbon and mercury electrodes. The reduction potentials showed the expected dependence on the number of electron-withdrawing nitro groups present on the porphyrin ring providing additional evidences for the characterisation of the synthesised compounds.

  1. Absorpsi dan Responsivitas Larutan Porphyrin Alam Hasil Isolasi dari Spirulina sebagai Bahan Material Photonics

    Directory of Open Access Journals (Sweden)

    Agus Supriyanto

    2017-03-01

    Full Text Available Telah dilakukan pengujian karakteristik absorpsi larutan porphyrin dan responsivitas cahaya. Larutan senyawa molekul porphyrin diisolasi dari mikroalgae spirulina. Pengujian fotokonduktivitas dalam kondisi gelap diperoleh sekitar 0,9x10-4 ohm-1.cm-1 sedangkan pada kondisi diberi intensitas radiasi 0,5 W.m-2, 10 W.m-2 dan 16 W.m-2 diperoleh fotokonduktivitas sekitar 1,5x10-4 ohm-1 cm-1. Spektrum absorbansi larutan porphyrin mempunyai soret band sekitar 410 nm dan Q-band sekitar 660 nm. Dari hasil perhitungan responsivitas cahaya pada larutan porphyrins dengan panjang gelombang 410 nm dan 660 nm mempunyai tanggapan cahaya yang baik yaitu sekitar 3,92x10-2 ampere/watt dan 5,53x10-2 ampere/watt. Sedangkan pada panjang gelombang lainnya diperoleh sekitar 1,39x10-9 ampere/watt. Hal ini cukup potensial bahwa material porphyrins alam dapat digunakan sebagai material photonics pada devais foto.

  2. Detection of a weak ring current in a nonaromatic porphyrin nanoring using magnetic circular dichroism.

    Science.gov (United States)

    Kowalska, Patrycja; Peeks, Martin D; Roliński, Tomasz; Anderson, Harry L; Waluk, Jacek

    2017-12-13

    We compare the absorption and magnetic circular dichroism (MCD) spectra of a series of porphyrin oligomers - dimer, tetramer, and hexamer - bound in a linear or cyclic fashion. The MCD signal is extremely weak for low energy transitions in the linear oligomers, but it is amplified when the cyclic porphyrin hexamer binds a template, restricting rotational freedom. The appearance of Faraday A terms in the MCD spectra demonstrates the presence of a magnetic moment, and thus, uncompensated electronic current. The value of the excited state magnetic moment estimated from the A term is very low compared with those of monomeric porphyrins, which confirms the nonaromatic character of the cyclic array and the lack of a global ring current in the ground state of the neutral nanoring. DFT calculations predict the absorption and MCD patterns reasonably well, but fail to reproduce the MCD sign inversion observed in substituted monomeric zinc porphyrins ("soft" chromophores). Interestingly, a correct sign pattern is predicted by INDO/S calculations. Analysis of the MCD spectra of the monomeric porphyrin unit allowed us to distinguish between two close-lying lowest energy transitions, which some previous assignments placed further apart. The present results prove the usefulness of MCD not only for deconvolution and assignment of electronic transitions, but also as a sensitive tool for detecting electronic ring currents.

  3. A panchromatic anthracene-fused porphyrin sensitizer for dye-sensitized solar cells

    KAUST Repository

    Ball, James M.

    2012-01-01

    The development of ruthenium-free sensitizers which absorb light over a broad range of the solar spectrum is important for improving the power conversion efficiency of dye-sensitized solar cells. Here we study three chemically tailored porphyrin-based dyes. We show that by fusing the porphyrin core to an anthracene unit, we can extend the conjugation length and lower the optical gap, shifting the absorption spectrum into the near-infrared (NIR). All three dyes were tested in dye-sensitized solar cells, using both titanium dioxide and tin dioxide as the electron-transport material. Solar cells incorporating the anthracene-fused porphyrin dye exhibit photocurrent collection at wavelengths up to about 1100 nm, which is the longest reported for a porphyrin-based system. Despite extending the photon absorption bandwidth, device efficiency is found to be low, which is a common property of cells based on porphyrin dyes with NIR absorption. We show that in the present case the efficiency is reduced by inefficient electron injection into the oxide, as opposed to dye regeneration, and highlight some important design considerations for panchromatic sensitizers. © 2012 The Royal Society of Chemistry.

  4. A new probe of solvent accessibility of bound photosensitizers. 1. Ruthenium(II) and osmium(II) photosensitizers in sodium lauryl sulfate micelles

    International Nuclear Information System (INIS)

    Hauenstein, B.L. Jr.; Dressick, W.J.; Buell, S.L.; Demas, J.N.; DeGraff, B.A.

    1983-01-01

    A new method of measuring solvent accessibility of photosensitizers bound to organized media is presented. In particular, the solvent accessibility of a series of ruthenium(II) and osmium(II) photosensitizers bound to sodium lauryl sulfate micelles has been determined. The method takes advantage of the large solvent deuterium effect on the excited-state lifetimes of these complexes. The solvent accessibility of the bound complexes correlates with the hydrophobicity of the ligands. The potential application of this method to a variety of other systems is mentioned

  5. Non-covalent synthesis of calix[4]arene-capped porphyrins in polar solvents via ionic interactions

    NARCIS (Netherlands)

    Fiammengo, R.; Timmerman, P.; Huskens, Jurriaan; Versluis, Kees; Heck, Albert J.R.; Reinhoudt, David

    2002-01-01

    Non-covalent synthesis of calix[4]arene capped porphyrins can be achieved in polar solvents (up to 45% molar fraction of water) via ionic interaction. Thus tetracationic meso-tetrakis(N-alkylpyridinium-3-yl) porphyrins 1a–d and tetra anionic 25,26,27,28-tetrakis(2-ethoxyethoxy)-calix[4]arene

  6. Porphyrins from Messel oil shale (Eocene, Germany): Structure elucidation, geochemical and biological significance, and distribution as a function of depth

    Science.gov (United States)

    Ocampo, Rubén; Bauder, Claude; Callot, Henry J.; Albrecht, Pierre

    1992-02-01

    The extraction and isolation procedures of twenty nickel porphyrins (seven alkylporphyrins, thirteen carboxylic acids) from lacustrine Messel shale (Eocene, Germany), as well as the unequivocal structural assignments (obtained using 200 and 400 MHz nuclear magnetic resonance (NMR), nuclear Overhauser effect, mass spectrometry and total or partial synthesis of six reference compounds) are described. Ten porphyrins could be specifically correlated with biological precursors: algal chlorophyll c (4), bacteriochlorophylls d (3) and heme (3), while the remaining ones may arise from several chlorophylls. The structures of these fossil pigments mostly confirm the classical "Treibs scheme," including the origin of some porphyrins from nonchlorophyll sources. They also show that, even in a very immature sediment, deep modifications occur, including, in particular, extensive degradation of chlorophyll E ring. The composition of the porphyrin fractions of Messel oil shale was also studied as a function of depth. A porphyrin acids/alkylporphyrins ratio varying from 0.35 to 24.8 demonstrated that the apparent homogeneity of the shale is not reflected on the molecular scale. This was confirmed when the abundance of the twenty individual porphyrins of known structure was measured along the core. Significant correlations between individual porphyrins were found: fossils of bacteriochlorophylls d, homolog pairs of porphyrins (3-H/3-ethyl), etc.

  7. Syntheses and biological evaluation of F-18 and I-123 labeled porphyrins as potential tumor imaging agents

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J. H.; Ji, D. Y. [Inha University, Incheon (Korea, Republic of); Moon, B. S.; Lee, T. S.; Lee, D. H.; Lee, K. C.; Ahn, G. I.; Yang, S. D.; Choi, C. W.; Jun, K. S. [KIRAMS, Seoul (Korea, Republic of)

    2005-07-01

    Photofrin has currently been approved for general use by licensing authorities to treatment for solid tumor and cancer using photodynamic therapy (PDT) that treat to photochemical effect induced by light. Recently, meso-tetra(3-hydroxyphenyl)porphyrin has been developed as one of best tumor localizer and also shown a favorable tissue distribution. We have studied to develop I-123 labeled meso-tetra(3-methoxyphenyl)porphyrins for tumor imaging. We have studied to develop iodine-123 labeled meso-tetra(3-carboxymethoxy phenyl)porphyrin for tumor imaging agent. The radioiodinated porphyrin compound was obtained by the iodination reaction of tin precursor (50 ig) of porphyrin with Na-123I (200 {mu}L, 100-200 mCi), in the presence of peracetic acid (40 {mu}L) in ethanol. Iodine-123 labeled porphyrin derivative was obtained in 20-30% radiochemical yield and purified by HPLC at 2 mL/min using EtOH/water gradient condition and the fraction at 24-26 min was collected and characterized to desired compound by co injection with cold porphyrin analogue. Total time was around 120 min. The in vitro and in vivo of I-123 labeled porphyrin derivative is under studying.

  8. The protective effect of caffeine on DNA photosensitive damage: a gel electrophoresis

    International Nuclear Information System (INIS)

    Huang Liping; Ma Jianhua

    2009-01-01

    Agarose gel electrophoresis was performed to study interaction effect of caffeine on photosensitive injury of DNA caused by anthraquinone-2-sulphonic acid disodium (AQS), a model compound of strong photosensitizer, under 254 nm or 365nm UV irradiation Photosensitive injury of DNA induced by AQS under deoxidized condition was used as control. The results show that caffeine may resist effectively the injury effect of photosensitive damage and strong UV irradiation on DNA. The effects depend on the caffeine and AQS concentration, and irradiation time. Caffeine in concentration of 0.01-3.0 μg/μL, may prevent DNA from damage induced by UV light, but caffeine in concentration of >5.0 μg/μL accelerates the DNA damage. In particular, in the aqueous solution system of DNA, caffeine and AQS, at pH 6.25-7.35, the caffeine in concentration of 2.5-4.50 μg/μL may resist the photosensitive injury of DNA caused by AQS under the deoxidized condition and exposure by 254 nm UV for 10 min. And caffeine in concentration of 5 μg/μL would present a synergetic effect on the photosensitive injury of DNA. Possible molecular mechanism also is discussed. (authors)

  9. Theoretical Study on the Photosensitizer Mechanism of Phenalenone in Aqueous and Lipid Media.

    Science.gov (United States)

    Espinoza, César; Trigos, Ángel; Medina, Manuel E

    2016-08-11

    The photosensitizer ability of phenalenone was studied in aqueous and lipid media through the single electron transfer reactions, employing the density functional theory. Although phenalenone is a well-known photosensitizer and is widely used as an (1)O2 reference sensitizer, little is known about the reaction mechanism involved. In this study we carried out a single electron transfer reaction between the basal, excited, oxidized and reduced state of phenalenone with oxygen molecules such as (3)O2 and O2(•-). In aqueous media the photosensitizer capacity of phenalenone was measured through both type I and type II mechanisms. In lipid media the photosensitizer ability of phenalenone was attributed to the type II mechanism. The results indicated that the photosensitizer ability of phenalenone shows a heavy reliance on the media where the reaction occurs whether this is an aqueous or lipid media. Finally, this study supports the idea about that electron transfer reactions can be used to study the photosensitizer ability of molecules.

  10. Modeling Photosensitized Secondary Organic Aerosol Formation in Laboratory and Ambient Aerosols.

    Science.gov (United States)

    Tsui, William G; Rao, Yi; Dai, Hai-Lung; McNeill, V Faye

    2017-07-05

    Photosensitized reactions involving imidazole-2-carboxaldehyde (IC) have been experimentally observed to contribute to secondary organic aerosol (SOA) growth. However, the extent of photosensitized reactions in ambient aerosols remains poorly understood and unaccounted for in atmospheric models. Here we use GAMMA 4.0, a photochemical box model that couples gas-phase and aqueous-phase aerosol chemistry, along with recent laboratory measurements of the kinetics of IC photochemistry, to analyze IC-photosensitized SOA formation in laboratory and ambient settings. Analysis of the laboratory results of Aregahegn et al. (2013) suggests that photosensitized production of SOA from limonene, isoprene, α-pinene, β-pinene, and toluene by 3 IC* occurs at or near the surface of the aerosol particle. Reactive uptake coefficients were derived from the experimental data using GAMMA 4.0. Simulations of aqueous aerosol SOA formation at remote ambient conditions including IC photosensitizer chemistry indicate less than 0.3% contribution to SOA growth from direct reactions of 3 IC* with limonene, isoprene, α-pinene, β-pinene, and toluene, and an enhancement of less than 0.04% of SOA formation from other precursors due to the formation of radicals in the bulk aerosol aqueous phase. Other, more abundant photosensitizer species, such as humic-like substances (HULIS), may contribute more significantly to aqueous aerosol SOA production.

  11. Novel approach to control Salmonella enterica by modern biophotonic technology: photosensitization.

    Science.gov (United States)

    Buchovec, I; Vaitonis, Z; Luksiene, Z

    2009-03-01

    Salmonellosis is one of the most common foodborne diseases in the world. The aim of this study was to evaluate the antibacterial efficiency of 5-aminolevulinic acid (ALA) based photosensitization against one of food pathogens Salmonella enterica. Salmonella enterica was incubated with ALA (7.5 mmol l(-1)) for 1-4 h and afterwards illuminated with visible light. The light source used for illumination of S. enterica emitted light lambda = 400 nm with energy density 20 mW cm(-2). The illumination time varied from 0 to 20 min and subsequently a total energy dose reached 0-24 J cm(-2). The data obtained indicate that S. enterica is able to produce endogenous photosensitizer PpIX when incubated with ALA. Remarkable inactivation of micro-organisms can be achieved (6 log) after photosensitization. It is obvious that photosensitization-based inactivation of S. enterica depends on illumination as well as incubation with ALA time. ALA-based photosensitization can be an effective tool against multi-drug resistant Gram-negative bacteria S. enterica serovar Typhimurium. Experimental data and mathematical evaluations support the idea that ALA-based photosensitization can be a useful tool for the development of nonthermal food preservation technology in future.

  12. Boron Doped Graphene 3-Dimensi untuk Superkapasitor Kapasitas Tinggi

    Directory of Open Access Journals (Sweden)

    Nurlia Pramita Sari

    2017-08-01

    Full Text Available Chemical doping is an effective approach to improve the property of carbon material. In this study boron doped graphene with 3D structure used as the electrode was investigated. Boron doped graphene was prepared through freeze-dried process followed by pyrolysis of graphene oxide (GO with three types of chemical substances; boron oxide, boric acid, and boron powder in an argon and hydrogen atmosphere at 1000 C for 3 hours. The difference of chemical composition generated a different percentage of boron bond with GO. The results shows that the highest electrochemical performance was found in graphene samples with the addition of boric acid (BA 86 F/g, followed by boron oxide (BO 59.2 F/g, and boron powder (BP 2 F/g. It can be caused by boron concentration bound with graphene. The higher concentration of boron could be increased the electrochemical performance due to better of ion movement.

  13. Breaking the icosahedra in boron carbide.

    Science.gov (United States)

    Xie, Kelvin Y; An, Qi; Sato, Takanori; Breen, Andrew J; Ringer, Simon P; Goddard, William A; Cairney, Julie M; Hemker, Kevin J

    2016-10-25

    Findings of laser-assisted atom probe tomography experiments on boron carbide elucidate an approach for characterizing the atomic structure and interatomic bonding of molecules associated with extraordinary structural stability. The discovery of crystallographic planes in these boron carbide datasets substantiates that crystallinity is maintained to the point of field evaporation, and characterization of individual ionization events gives unexpected evidence of the destruction of individual icosahedra. Statistical analyses of the ions created during the field evaporation process have been used to deduce relative atomic bond strengths and show that the icosahedra in boron carbide are not as stable as anticipated. Combined with quantum mechanics simulations, this result provides insight into the structural instability and amorphization of boron carbide. The temporal, spatial, and compositional information provided by atom probe tomography makes it a unique platform for elucidating the relative stability and interactions of primary building blocks in hierarchically crystalline materials.

  14. Boron adsorption on hematite and clinoptilolite

    International Nuclear Information System (INIS)

    Gainer, G.M.

    1993-01-01

    This thesis describes experiments performed to determine the suitability of boron as a potential reactive tracer for use in saturated-zone C-well reactive tracer studies for the Yucca Mountain Project (YMP). Experiments were performed to identify the prevalent sorption mechanism of boron and to determine adsorption of boron on hematite and clinoptilolite as a function of pH. These minerals are present in the Yucca Mountain tuff in which the C-well studies will be conducted. Evaluation of this sorption mechanism was done by determining the equilibration time of boron-mineral suspensions, by measuring changes in equilibrium to titrations, and by measuring electrophoretic mobility. Experiments were performed with the minerals suspended in NaCl electrolytes of concentrations ranging from 0.1 N NaCl to 0.001 N NaCl. Experimentalconditions included pH values between 3 and 12 and temperature of about 38 degrees C

  15. Determination of boron in amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Grazhulene, S.S.; Grossman, O.V.; Kuntscher, K.K.; Malygina, L.I.; Muller, E.N.; Telegin, G.F.

    1985-10-01

    In the determination of boron in amorphous alloys containingFe, Co, B, Si, Ni, and P having unusal magnetic and electrical properties, precise analysis and rapid analysis are necessary. To improve the metrological properties of the existing procedure, to find a rapid determination of boron in amorphous alloys, and to verify the accuracy of the results, in the present work the optimization of the photometric determination after extraction of the BF/sup -//sub 4/ ion pair with methylene blue has been studied, and a boron determination by flame photometry using selective methylation has been developed. The determination of boron by the flame photometric and spectrophotometric methods is shown. When a highly precise determination is needed, the spectrophotometric procedure can be used. This procedure is distinguished by its labor intensity and duration. When the need for reproducibility is less severe, the rapid flame photometric procedure is best.

  16. Boron precipitates in ion implanted silicon

    International Nuclear Information System (INIS)

    Wu, W.K.; Washburn, J.

    1975-03-01

    Long rod-like defects are observed in ion implanted silicon when boron is present either as a prior dopant addition or as the implanted species. Results of recent work indicates that these defects have the characteristics of narrow extrinsic dipoles or elongated dislocation loops and that there are two different types along each of the six (110) directions. An annealing kinetics method has been used to identify the nature of these defects formed during post-implantation annealing in boron ion (100 keV) implanted silicon irradiated at room temperature to a dose of 2 x 10 14 /cm 2 . It is concluded that at least two different kinds of rod-like defects exist in boron ion implanted silicon. From the activation energy for shrinkage, it is also concluded that one type (anti A) is composed largely of boron atoms. (U.S.)

  17. Spectromicroscopy in Boron Neutron Capture Therapy Research

    Science.gov (United States)

    Gilbert, Benjamin; Redondo, Jose; Andres, Roger; Suda, Takashi; Neumann, Michael; Steen, Steffi; Gabel, Detlef; Mercanti, Delio; Ciotti, Teresa; Perfetti, Paolo; Margaritondo, Giorgio; de Stasio, Gelsomina

    1998-03-01

    The MEPHISTO synchrotron imaging spectromicroscope can analyse ashed cells or tissue sections to reveal the microdistribution of trace elements. MEPHISTO performs core level x-ray absorption spectroscopy with synchrotron radiation, and uses an electron optics system to provide magnified photoelectron images. An application of the MEPHISTO spectromicroscope is in boron neutron capture therapy (BNCT). BNCT is a binary cancer therapy that will selectively destroy cancer cells provided that compounds containing a boron isotope are selectively accumulated in tumor tissue. Important factors for the success of BNCT include the ability to target every cancer cell, and the distribution of boron inside the cell. To investigate the boron distribution in tissue, sections of human glioblastoma containing a BNCT compound, and stained with nickel against a protein found in the nuclei of proliferating (cancer) cells, were studied with MEPHISTO.

  18. Behaviour of boron in Mandovi estuary (Goa)

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Anand, S.P.

    and alkalinity gave positive correlations with a linear variation. Though the overall behavioural pattern of boron indicated non-conservative nature, it showed a quasi-conservative character during premonsoon and a non-conservative during rest of the seasons...

  19. Boron

    Science.gov (United States)

    ... feeding women over 19 years of age. For adolescents 14 to 18 years of age and pregnant or breast-feeding women 14 to 18 years of age, the ... be expected, is 17 mg per day for adolescents 14 to 18 years of age and pregnant or breast-feeding women 14 to 18 years of age. For ...

  20. Abrasive slurry composition for machining boron carbide

    Science.gov (United States)

    Duran, Edward L.

    1985-01-01

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.