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  Subjects -> CHEMISTRY (Total: 762 journals)
    - ANALYTICAL CHEMISTRY (45 journals)
    - CHEMISTRY (527 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (24 journals)
    - INORGANIC CHEMISTRY (40 journals)
    - ORGANIC CHEMISTRY (40 journals)
    - PHYSICAL CHEMISTRY (64 journals)

CHEMISTRY (527 journals)            First | 1 2 3 4 5 6 | Last

Journal of Inclusion Phenomena and Macrocyclic Chemistry     Hybrid Journal   (2 followers)
Journal of Inorganic Biochemistry     Hybrid Journal   (3 followers)
Journal of Labelled Compounds and Radiopharmaceuticals     Hybrid Journal  
Journal of Macromolecular Science, Part A: Pure and Applied Chemistry     Hybrid Journal   (4 followers)
Journal of Mass Spectrometry     Hybrid Journal   (19 followers)
Journal of Materials Chemistry A     Full-text available via subscription   (22 followers)
Journal of Materials Chemistry B     Full-text available via subscription   (5 followers)
Journal of Materials Chemistry C     Full-text available via subscription   (6 followers)
Journal of Materials Research     Full-text available via subscription   (8 followers)
Journal of Mathematical Chemistry     Hybrid Journal   (4 followers)
Journal of Medicinal Chemistry     Full-text available via subscription   (102 followers)
Journal of Membrane Science     Hybrid Journal   (8 followers)
Journal of Modern Chemistry & Chemical Technology     Full-text available via subscription   (1 follower)
Journal of Molecular Catalysis A: Chemical     Hybrid Journal   (2 followers)
Journal of Molecular Graphics and Modelling     Hybrid Journal   (3 followers)
Journal of Molecular Liquids     Hybrid Journal   (3 followers)
Journal of Molecular Modeling     Hybrid Journal   (3 followers)
Journal of Molecular Recognition     Hybrid Journal  
Journal of Molecular Spectroscopy     Hybrid Journal   (6 followers)
Journal of Molecular Structure     Hybrid Journal   (3 followers)
Journal of Nanostructure in Chemistry     Open Access   (5 followers)
Journal of Natural Gas Chemistry     Full-text available via subscription   (2 followers)
Journal of Nepal Chemical Society     Open Access  
Journal of Nucleic Acids Investigation     Open Access   (2 followers)
Journal of Ocean University of China (English Edition)     Hybrid Journal   (2 followers)
Journal of Organometallic Chemistry     Hybrid Journal   (12 followers)
Journal of Photochemistry and Photobiology A: Chemistry     Hybrid Journal   (3 followers)
Journal of Photochemistry and Photobiology C: Photochemistry Reviews     Full-text available via subscription   (4 followers)
Journal of Polymer Science Part A: Polymer Chemistry     Hybrid Journal   (122 followers)
Journal of Polymers     Open Access  
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (2 followers)
Journal of Pure and Applied Chemistry Research     Open Access  
Journal of Raman Spectroscopy     Hybrid Journal   (9 followers)
Journal of Saudi Chemical Society     Open Access  
Journal of Solid State Chemistry     Hybrid Journal   (12 followers)
Journal of Solution Chemistry     Hybrid Journal  
Journal of Structural Chemistry     Hybrid Journal  
Journal of Sulfur Chemistry     Hybrid Journal   (2 followers)
Journal of Superhard Materials     Hybrid Journal   (1 follower)
Journal of Surfactants and Detergents     Hybrid Journal   (5 followers)
Journal of Systems Chemistry     Open Access   (1 follower)
Journal of Taibah University for Science     Open Access  
Journal of the American Chemical Society     Full-text available via subscription   (183 followers)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (15 followers)
Journal of the American Society of Brewing Chemists     Full-text available via subscription   (1 follower)
Journal of the Bangladesh Chemical Society     Open Access  
Journal of the Chilean Chemical Society     Open Access   (2 followers)
Journal of the Iranian Chemical Society     Hybrid Journal   (1 follower)
Journal of the Korean Society for Applied Biological Chemistry     Hybrid Journal   (1 follower)
Journal of the Mexican Chemical Society     Open Access   (1 follower)
Journal of Theoretical and Computational Chemistry     Hybrid Journal   (6 followers)
Journal of Theoretical Chemistry     Open Access  
Journal of Wood Chemistry and Technology     Hybrid Journal   (7 followers)
JPC - Journal of Planar Chromatography - Modern TLC     Full-text available via subscription   (5 followers)
Jurnal Penelitian Sains (JPS)     Open Access  
Jurnal Teknologi Informasi     Open Access   (3 followers)
Kinetics and Catalysis     Hybrid Journal   (3 followers)
Korea-Australia Rheology Journal     Hybrid Journal  
Langmuir     Full-text available via subscription   (35 followers)
Latvian Journal of Chemistry     Open Access   (1 follower)
Lebensmittelchemie     Hybrid Journal   (1 follower)
Lipid Insights     Open Access   (1 follower)
Luminescence     Hybrid Journal   (1 follower)
Macromolecular Materials & Engineering     Hybrid Journal   (2 followers)
Macromolecular Rapid Communications     Hybrid Journal   (4 followers)
Macromolecular Research     Hybrid Journal  
Macromolecular Symposia     Hybrid Journal  
Macromolecular Theory and Simulations     Hybrid Journal  
Macromolecules     Full-text available via subscription   (31 followers)
Magnetic Resonance in Chemistry     Hybrid Journal   (4 followers)
Main Group Chemistry     Hybrid Journal  
Marine Chemistry     Hybrid Journal   (4 followers)
Marine Drugs     Open Access   (4 followers)
MATEC Web of Conferences     Open Access  
Materials Characterization     Hybrid Journal   (21 followers)
Materials Horizons     Full-text available via subscription  
Materials Research Bulletin     Hybrid Journal   (14 followers)
Materials Science Monographs     Full-text available via subscription   (1 follower)
Materials Science-Poland     Hybrid Journal  
Materials Sciences and Applications     Open Access   (4 followers)
MedChemComm     Full-text available via subscription   (3 followers)
Medicinal Chemistry Research     Hybrid Journal   (8 followers)
Metallography, Microstructure, and Analysis     Hybrid Journal   (1 follower)
Metallomics     Full-text available via subscription  
Micro and Nano Systems Letters     Open Access   (1 follower)
Microchimica Acta     Hybrid Journal   (1 follower)
Microporous and Mesoporous Materials     Hybrid Journal   (3 followers)
Modern Research in Catalysis     Open Access   (1 follower)
Molbank     Open Access  
Molecules     Open Access   (2 followers)
Molecules and Cells     Hybrid Journal   (1 follower)
Monatshefte für Chemie - Chemical Monthly     Hybrid Journal   (3 followers)
Moscow University Chemistry Bulletin     Hybrid Journal   (2 followers)
MRS Bulletin     Full-text available via subscription   (4 followers)
MRS Online Proceedings     Full-text available via subscription   (1 follower)
Nachrichten aus der Chemie     Full-text available via subscription   (1 follower)
Nano Reviews     Open Access   (15 followers)
Nanomaterials and the Environment     Open Access  
Nanoscale     Full-text available via subscription   (11 followers)
Nanoscale Research Letters     Open Access   (4 followers)

  First | 1 2 3 4 5 6 | Last

Photochemistry and Photobiology    [3 followers]  Follow    
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0031-8655 - ISSN (Online) 1751-1097
     Published by John Wiley and Sons Homepage  [1594 journals]   [SJR: 0.709]   [H-I: 86]
  • Analysis of Photoexcitation Energy Dependence in the Photo Luminescence of
           Firefly Luciferin
    • Authors: Miyabi Hiyama; Hidefumi Akiyama, Toshimitsu Mochizuki, Kenta Yamada, Nobuaki Koga
      Pages: n/a - n/a
      Abstract: The whole pathways for photo luminescence, which include absorption, relaxation and emission, of firefly luciferin in aqueous solutions of different pH values with different photoexcitation energies were theoretically investigated by considering protonation/ deprotonation. It is experimentally known that the colour of fluorescence changes from green to red with a decrease in the photoexcitation energy. We confirmed with the theoretical analysis that the peak energy shift in the fluorescence spectra with varying photoenergies is due to a change in photo luminescence pathway. When the photoexcitation energy is decreased, the red emission from a monoanion form of firefly luciferin with carboxylate and phenolate groups and N‐protonated thiazoline ring occurs irrespective of the pH values. However, because the species abundant in the solution and those excited by the photon depend on the solution pH, the pathway leading to the monoanion form changes with the solution pH. This article is protected by copyright. All rights reserved.
      PubDate: 2014-01-22T04:33:50.262378-05:
      DOI: 10.1111/php.12243
       
  • The Effect of Loading Palladium on Zinc Oxide on the Photocatalytic
           Degradation of Methyl tert‐Butyl Ether (MTBE) in Water
    • Authors: Zaki S. Seddigi; Saleh A. Ahmed, Shahid P. Ansari, Naeema H. Yarkandi, Ekram Danish, Abdullah Abu Alkibash, Mohammed D. Y. Oteef, Shakeel Ahmed
      Pages: n/a - n/a
      Abstract: A series of heterogeneous catalysts was prepared by doping zinc oxide with different palladium loadings in the range of 0.5% ‐ 1.5%. The prepared catalysts were characterized by SEM, TEM and XRD. These catalysts were applied to study the degradation of MTBE. An amount of 100 mg of each of these catalysts was added to an aqueous solution of 100 ppm of MTBE. The resulting mixtures were irradiated with UV light for a period of five hours. A 99.7% removal of MTBE was achieved in the case of the zinc oxide photocatalyst particles doped with 1% Pd. The photoreaction was found to be a first order one. This article is protected by copyright. All rights reserved.
      PubDate: 2014-01-21T10:56:18.244308-05:
      DOI: 10.1111/php.12242
       
  • Home Lighting Before Usual Bedtime Impacts Circadian Timing: A Field Study
    • Authors: Helen J. Burgess; Thomas A. Molina
      Pages: n/a - n/a
      Abstract: Laboratory studies suggest that evening light before bedtime can suppress melatonin. Here we measured the range of evening light intensity people can generate with their household lights, and for the first time determined if varying home light before usual bedtime can shift circadian phase. This was a 3‐week study with two counterbalanced conditions separated by a 5‐day break. In a dim week, 8 healthy subjects minimized their home light exposure from 4 hours before habitual bedtime until a self‐selected bedtime. In a bright week, the subjects maximized their home lighting for the same time. The dim light melatonin onset (DLMO) was assessed after each week. On average subjects maximized their lights to ~65 lux and minimized their lights to ~3 lux. Wrist actigraphy indicated that subjects went to bed slightly later when lights were maximized (average 14 minutes later, p=0.05), but wake time did not change. Every subject had a later DLMO after the week of maximum versus minimum light exposure (average 1:03 h later, p
      PubDate: 2014-01-19T04:05:39.689063-05:
      DOI: 10.1111/php.12241
       
  • Early diagnosis of colorectal cancer in rats with DMH induced
           carcinogenesis by means of urine autofluorescence analysis
    • Authors: Zuzana Šteffeková; Anna Birková, Alojz Bomba, Mária Mareková
      Pages: n/a - n/a
      Abstract: Cancer is one of the most highlighted topics of current research. Early detection of this disease allows more effective therapy, hence higher chance of cure. Application of fluorescence spectral techniques into oncological diagnostic is one of the potential alternatives. Chemically induced carcinogenesis in rats is widely used model for exploration of various aspects of colorectal cancer. This paper shows value of discriminate analysis of urine fluorescent fingerprint between healthy control group of rats and those with dimethylhydrazine induced early lesions of colorectal cancer. Using fluorescence spectroscopy significant difference (P
      PubDate: 2014-01-19T04:05:35.676699-05:
      DOI: 10.1111/php.12240
       
  • Effect of Light on Expression of Clock Genes in Xenopus laevis
           Melanophores
    • Authors: Maria Nathália de Carvalho Magalhães Moraes; Maristela Oliveira Poletini, Bruno Cesar Ribeiro Ramos, Leonardo Henrique Ribeiro Graciani Lima, Ana Maria Lauro Castrucci
      Pages: n/a - n/a
      Abstract: Light–dark cycles are considered important cues to entrain biological clocks. A feedback loop of clock gene transcription and translation is the molecular basis underlying the mechanism of both central and peripheral clocks. Xenopus laevis embryonic melanophores respond to light with melanin granule dispersion, response possibly mediated by the photopigment melanopsin. To test whether light modulates clock gene expression in Xenopus melanophores, we used qPCR to evaluate the relative mRNA levels of Per1, Per2, Clock and Bmal1 in cultured melanophores exposed to light–dark (LD) cycle or constant darkness (DD). LD cycles elicited temporal changes in the expression of Per1, Per2 and Bmal1. A 10‐min pulse of blue light was able to increases the expression of Per1 and Per2. Red light had no effect on the expression of these clock genes. These data suggest the participation of a blue‐wavelength sensitive pigment in the light–dark cycle‐mediated oscillation of the endogenous clock. Our results add an important contribution to the emerging field of peripheral clocks, which in nonmammalian vertebrates have been mostly studied in Drosophila and Danio rerio. Within this context, we show that X. laevis melanophores, which have already led to melanopsin discovery, represent an ideal model to understanding circadian rhythms. In light‐sensitive cells, environmental light may be transduced through melanopsins (pigment excited by short wavelength) which, in turn, regulates the machinery of endogenous molecular clock through an increase in Per1 expression. In a nonmammalian vertebrate cell line (X. laevis melanophore), we demonstrated that a blue‐light pulse increases Per1 and Per2 expression, and that Per1 gene expression oscillates in a circadian fashion under light–dark cycle. Thus, these cells are a promising model to investigate the biological mechanisms involved in photoentrainment in peripheral clocks.
      PubDate: 2014-01-18T00:03:00.309864-05:
      DOI: 10.1111/php.12230
       
  • Photosensitive and biomimetic core‐shell nanofibrous scaffolds as
           wound dressing
    • Authors: Guorui Jin; Molamma P Prabhakaran, Seeram Ramakrishna
      Pages: n/a - n/a
      Abstract: Tissue engineered skin grafts that mimic the native extracellular matrix (ECM) of skin has gained huge popularity among clinicians since they increase the survival rate of the patients. Phototherapy shows promising results with respect to acute and chronic pain relief, treatment of inflammatory conditions, and promotion of wound healing. Here, we encapsulated a photosensitive polymer poly (3‐hexylthiophene) (P3HT) and epidermal growth factor (EGF) in the core‐shell structured Gelatin/poly(L‐lactic acid)‐co‐poly‐(ε‐caprolactone) nanofibers [Gel/PLLCL/P3GF(cs)] by coaxial spinning and studied the potential application of the Gel/PLLCL/P3GF(cs) nanofibrous scaffold as a novel skin graft. The proliferation of fibroblasts was significantly improved on Gel/PLLCL/P3GF(cs) under light stimulation compared to fibroblasts on the same scaffold under dark condition. Studies on the in vitro wound healing ability of Gel/PLLCL/P3GF(cs) showed complete closure of wound after 9 days under ‘light stimulation’ too. Further the potential of adipose derived stem cells (ASCs) to differentiate to epidermal cells on Gel/PLLCL/P3GF(cs) was evaluated. The differentiated ASCs with keratinocytes morphology were only found on the light stimulated Gel/PLLCL/P3GF(cs). Our results suggest that the photosensitive core‐shell Gel/PLLCL/P3GF(cs) nanofibers could be a novel substrate to aid in the re‐establishment of skin architecture. This article is protected by copyright. All rights reserved.
      PubDate: 2014-01-13T10:54:37.144183-05:
      DOI: 10.1111/php.12238
       
  • Shade Provision For Uv Minimisation: A Review
    • Authors: A.V. Parisi; D.J. Turnbull
      Pages: n/a - n/a
      Abstract: Minimising exposure to ultraviolet (UV) radiation is an essential component of skin cancer prevention. Providing and using natural and built shade is an effective protection measure against harmful UV. This article describes the factors that must be addressed to ensure quality, effective, well designed shade and recommends best practice approaches to improving the protection factor (PF) of shade structures. It identifies examples of interventions to increase shade availability and use, and examples of effective shade based on measured protection factors or measured reductions in UV exposures. Finally, this article considers examples of best practice for undertaking shade audits. The article is based on refereed papers and reviews, reports, conference papers, and shade practice and policies from reports and on web sites. Articles for the Australian setting are considered first, followed by those in an international setting. This article is protected by copyright. All rights reserved.
      PubDate: 2014-01-13T10:54:26.933784-05:
      DOI: 10.1111/php.12237
       
  • Synthesis and Characterization of Near Infrared Absorbing Water Soluble
           Squaraines and Study of their Photodynamic Effects in DLA Live Cells
    • Authors: Kulathinte M. Shafeekh; Mohanannair S. Soumya, Moochikkadavath A. Rahim, Annie Abraham, Suresh Das
      Pages: n/a - n/a
      Abstract: Here we report the synthesis, photophysical properties and photodynamic effects in DLA live cells of three water soluble squaraine dyes, viz. bisbenzothiazolium squaraine dyes SQMI and SQDI with iodine in one and both benzothiazolium units respectively and an unsymmetrical squaraine dye ASQI containing iodinated benzothiazolium and aniline substituents. The diiodinated SQDI showed an anomalous trend in both fluorescence and triplet quantum yields over the monoiodinated SQMI, with SQDI showing higher fluorescence and lower triplet quantum yields compared to SQMI. Nanosecond laser flash photolysis of SQDI and SQMI indicated the formation of triplet excited states with quantum yield of 0.19 and 0.26 respectively. On photoirradiation, both the SQDI and SQMI generate singlet oxygen and it was observed that both dyes undergoing oxidation reactions with the singlet oxygen generated. ASQI which exhibited a lower triplet quantum yield of 0.06 was however stable and did not react with the singlet oxygen generated. In vitro cytotoxicity studies of these dyes in DLA live cells were performed using Trypan blue dye exclusion method and it reflect an order of cytotoxicity of SQDI>SQMI>ASQI. Intracellular generation of the ROS was confirmed by dichlorofluorescein assay after the in vitro PDT. This article is protected by copyright. All rights reserved.
      PubDate: 2014-01-13T00:42:12.955227-05:
      DOI: 10.1111/php.12236
       
  • Photophysical properties of metal ion functionalized NaY zeolite
    • Authors: Tian‐Wei Duan; Bing Yan
      Pages: n/a - n/a
      Abstract: A series of luminescent ion exchanged zeolite are synthesized by introducing various ions into NaY zeolite. Monometal ion (Eu3+, Tb3+, Ce3+, Y3+, Zn2+, Cd2+, Cu2+) exchanged zeolite, rare earth ion (Eu3+, Tb3+, Ce3+) exchanged zeolite modified with Y3+ and rare earth ion (Eu3+, Tb3+, Ce3+) exchanged zeolite modified with Zn2+ are discussed here. The resulting materials are characterized by FTIR, XRD, SEM, PLE, PL and luminescence lifetime measurements. The photoluminescence spectrum of NaY indicates that emission band of host matrix exhibits a blue shift of about 70 nm after monometal ion exchange process. The results show that transition metal ion exchanged zeolites possess a similar emission band due to dominant host luminescence. A variety of luminescence phenomenon of rare earth ion broadens the application of zeolite as a luminescent host. The Eu3+ ion exchanged zeolite shows white light luminescence with a great application value and Ce3+ exchanged zeolite steadily exhibits it characteristic luminescence in ultraviolet region no matter in monometal ion exchanged zeolite or bimetal ions exchanged zeolite. This article is protected by copyright. All rights reserved.
      PubDate: 2014-01-06T12:47:06.286644-05:
      DOI: 10.1111/php.12235
       
  • Practical labeling methodology for choline‐derived lipids and
           applications in live cell fluorescence imaging
    • Authors: Caishun Li; Jessie A. Key, Feng Jia, Arpan Dandapat, Soo Hur, Christopher W. Cairo
      Pages: n/a - n/a
      Abstract: Lipids of the plasma membrane participate in a variety of biological processes, and methods to probe their function and cellular location are essential to understanding biochemical mechanisms. Previous reports have established that phosphocholine‐containing lipids can be labeled by alkyne groups through metabolic incorporation. Herein, we have tested alkyne, azide, and ketone‐containing derivatives of choline as metabolic labels of choline‐containing lipids in cells. We also show that 17‐octadecynoic acid can be used as a complementary metabolic label for lipid acyl chains. We provide methods for the synthesis of cyanine‐based dyes that are reactive with alkyne, azide, and ketone metabolic labels. Using an improved method for fluorophore conjugation to azide or alkyne‐modified lipids by Cu(I)‐catalyzed azide‐alkyne cycloaddition (CuAAC) we apply this methodology in live cells. Lipid‐labeled cell membranes were then interrogated using flow cytometry and fluorescence microscopy. Furthermore, we explored the utility of this labeling strategy for use in live cell experiments. We demonstrate measurements of lipid dynamics (lateral mobility) by fluorescence photobleaching recovery (FPR). Additionally, we show that adhesion of cells to specific surfaces can be accomplished by chemically linking membrane lipids to a functionalized surface. The strategies described provide robust methods for introducing bioorthogonal labels into native lipids. This article is protected by copyright. All rights reserved.
      PubDate: 2014-01-03T02:41:21.371044-05:
      DOI: 10.1111/php.12234
       
  • Photobiological Interactions of Blue Light and Photosynthetic Photon Flux:
           Effects of Monochromatic and Broad‐Spectrum Light Sources
    • Authors: Kevin R. Cope; M. Chase Snowden, Bruce Bugbee
      Pages: n/a - n/a
      Abstract: Photosynthesis (Pn) and photomorphogenesis (Pm) are affected by light quality, light intensity and photoperiod. Although blue light (BL) is necessary for normal development, it is less efficient in driving Pn than other wavelengths of photosynthetically active radiation. The effects of BL on Pm are highly species‐dependent. Here we report the interacting effects of BL and photosynthetic photon flux (PPF) on growth and development of lettuce, radish, and pepper. We used LED arrays to provide BL fractions from 11 to 28% under broad‐spectrum white LEDs, and from 0.3 to 92% under monochromatic LEDs. All treatments were replicated three times at each of two PPFs (200 and 500 μmol m‐2 s‐1). Other than light quality, environmental conditions were uniformly maintained across chambers. Regardless of PPF, BL was necessary to prevent shade‐avoidance responses in radish and lettuce. For lettuce and radish, increasing BL reduced stem length, and for both species, there were significant interactions of BL with PPF for leaf expansion. Increasing BL reduced petiole length in radish and flower number in pepper. BL minimally affected pepper growth and other developmental parameters. Pepper seedlings were more photobiologically sensitive than older plants. Surprisingly, there were surprisingly few interactions between monochromatic and broad‐spectrum light sources. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-26T08:13:34.79068-05:0
      DOI: 10.1111/php.12233
       
  • Novel photodynamic effect of a psoralen‐conjugated oligonucleotide
           for the discrimination of the methylation of cytosine in DNA
    • Authors: Asako Yamayoshi; Yohei Matsuyama, Mikihiko Kushida, Akio Kobori, Akira Murakami
      Pages: n/a - n/a
      Abstract: DNA methylation and demethylation significantly affects the deactivation and activation processes of gene expression significantly. In particular, the C‐5‐methylation of cytosine in the CpG islands is important for the epigenetic modification of genes, which plays a key role in regulating gene transcription. The determination of the location and frequency of DNA methylation is important for the elucidation of the mechanisms of cell differentiation and carcinogenesis. Here we designed a psoralen‐conjugated oligonucleotide (PS‐oligo) for the detection of 5‐methylcytosine (5‐mC) in DNA. The cross‐linking behavior of psoralen derivatives with pyrimidine bases, such as thymine, uracil and cytosine has been well discussed, but there are few reports have examined whether cross‐linking efficiency of psoralen with cytosine would be changed with or without C‐5 methylation. We found that the cross‐linking efficiency of PS‐oligo with target‐DNA containing 5‐mC was greatly increased compared to the case of target‐DNA without 5‐mC, approximately seven‐fold higher. Here we report a new aspect of the photo‐cross‐linking behavior of psoralen with 5‐mC that is applicable to a simple, sequence‐specific and quantitative analysis for the discrimination of 5‐mC in DNA, which can be applicable to study the epigenetic behavior of gene expressions. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-26T08:13:31.277722-05:
      DOI: 10.1111/php.12232
       
  • Novel Porphyrazine Derivatives show Promise for PDT despite Restrictions
           in Hydrophilicity
    • Authors: Tamarisk K Horne; Marianne J Cronjé
      Pages: n/a - n/a
      Abstract: Complexing of ligands to photosensitizers (Ps) has gained popularity by enhancing solubility, cell‐surface recognition and tissue specificity for applications in Photodynamic Therapy (PDT) and fluorescence‐based diagnostics. Here we report on nine carbohydrate‐functionalized porphyrazine (Pz‐galactopyranose / methyl‐ribose) derivatives bearing either H2, Zn(II) or Ni(II) cores for potential use in PDT. Derivatives proved soluble only in organic solvents; dichloromethane (DCM) and tetrahydrofuran (THF). Derivatives were subsequently solubilized using DCM‐based PEG‐DSPE5000‐PBS encapsulation for biological studies due to THF cytotoxicity. Absorption spectra analyses viewed no correlation between core ion, carbohydrate type and peripheral position though encapsulation efficiency (%EE) followed a general order of Zn(II) (60‐92%)>H2 (5‐34%)>Ni(II) (4‐21%). As such, phototoxicity of Zn(II)Pz derivatives were far superior to H2Pz and Ni(II)Pz counterparts following 631.4 nm excitation of MCF‐7 breast cancer cells. Variation was attributed to persistent aggregation and low%EE when regarding the absorption properties recorded. It is therefore believed that revision of the encapsulation method for H2Pz and Ni(II)Pz derivatives would render improved phototoxicity. Zn(II)Pz derivatives show promise as agents for PDT of cancer. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-26T08:13:22.353799-05:
      DOI: 10.1111/php.12231
       
  • Effect of Light on Expression of Clock Genes in Xenopus laevis
           Melanophores
    • Authors: Maria Nathália Moraes; Maristela Poletini, Bruno Cesar Ribeiro Ramos, Leonardo Henrique Ribeiro Graciani Lima, Ana Maria Castrucci
      Pages: n/a - n/a
      Abstract: Light‐dark cycles are considered important cues to entrain biological clocks. A feedback loop of clock gene transcription and translation is the molecular basis underlying the mechanism of both central and peripheral clocks. Xenopus laevis embryonic melanophores respond to light with melanin granule dispersion, response possibly mediated by the photopigment melanopsin. In order to test whether light modulates clock gene expression in Xenopus melanophores, we used qPCR to evaluate the relative mRNA levels of Per1, Per2, Clock and Bmal1 in cultured melanophores exposed to light‐dark (LD) cycle or constant darkness (DD). LD cycles elicited temporal changes in the expression of Per1, Per2 and Bmal1. A 10‐min pulse of blue light was able to increase the expression of Per1 and Per2. Red light had no effect on the expression of these clock genes. These data suggest the participation of a blue‐wavelength sensitive pigment in the light‐dark cycle‐mediated oscillation of the endogenous clock. Our results add an important contribution to the emerging field of peripheral clocks, which in non‐mammalian vertebrates have been mostly studied in Drosophila and Danio rerio. Within this context, we show that Xenopus laevis melanophores, which have already led to melanopsin discovery, represent an ideal model to understanding circadian rhythms. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-26T07:09:26.462616-05:
      DOI: 10.1111/j.1751-1097.2013.12230.x
       
  • Biochemical Composition and Antioxidant Properties of Lavandula
           angustifolia Miller Essential Oil are Shielded by Propolis against UV
           Radiations
    • Authors: Gismondi Angelo; Canuti Lorena, Grispo Marta, Canini Antonella
      Pages: n/a - n/a
      Abstract: UV radiations are principal causes of skin cancer and aging. Suntan creams were developed to protect epidermis and derma layers against photodegradation and photooxidation. The addition of antioxidant plant extracts (i.e. essential oil) to sunscreens is habitually performed, in order to increase their UV protective effects and to contrast pro‐radical and cytotoxic compounds present in these solutions. According to these observations, in the present work, the alteration of chemical composition and bioactive properties of Lavandula angustifolia Mill. essential oil, exposed to UV light, was investigated. UV induced a significant deterioration of Lavender oil biochemical profile. Moreover, the antioxidant activity of this solution, in in vitro tests and directly on B16‐F10 melanoma cells, greatly decreased after UV treatment. Our results also showed that essential oil was shielded from UV stress by propolis addition. Even after UV treatment, bee glue highly protected Lavender oil secondary metabolites from degradation and also preserved their antiradical properties, both in in vitro antioxidant assays and in cell oxidative damage evaluations. This research proposed propolis as highly efficient UV protective and antiradical additive for sunscreens, cosmetics and alimentary or pharmaceutical products containing plant extracts. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-23T06:15:33.088769-05:
      DOI: 10.1111/php.12229
       
  • Photodamage in a Mitochondrial Membrane Model Modulated by the Topology of
           Cationic and Anionic Meso‐Tetrakis Porphyrin Free Bases
    • Authors: Cintia Kawai; Juliana C. Araújo‐Chaves, Taciana Magrini, Camila O. C. C. Sanches, Sandra M. S. Pinto, Herculano Martinho, Nasser Daghastanli, , Iseli L. Nantes
      Pages: n/a - n/a
      Abstract: The photodynamic effects of the cationic TMPyP (meso‐tetrakis [N‐methyl‐4‐pyridyl]porphyrin) and the anionic TPPS4 (meso‐tetrakis[4‐sulfonatophenyl]porphyrin) against PC/CL phosphatidylcholine/cardiolipin (85/15%) membranes were probed to address the influence of phorphyrin binding on lipid damage. Electronic absorption spectroscopy and zeta potential demonstrated that only TMPyP binds to PC/CL large unilamellar vesicles (LUVs). The photodamage after irradiation with visible light was analyzed by dosages of lipid peroxides (LOOH) and thiobarbituric reactive substance and by a contrast phase image of the giant unillamelar vesicles (GUVs). Both TMPyP and TPPS4 promoted differentiated quantitative and qualitative damages on LUVs and GUVs. The damages were more extensive and faster by using the cationic porphyrin. The increase of LOOH was higher in the presence of D2O, and was impaired by sodium azide and sorbic acid. The effect of D2O was higher for TPPS4 as the photosensitizer. The use of DCFH demonstrated that liposomes prevent the photo‐bleaching of TMPyP. The results are consistent with a more stable TMPyP that generates long‐lived singlet oxygen preferentially partitioned in the bilayer. Conversely, TPPS4 generates singlet oxygen in the bulk whose lifetime is increased in D2O. Therefore, the affinity of the porphyrin to the membrane modulates the rate, type and degree of lipid damage. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-18T10:11:08.90148-05:0
      DOI: 10.1111/php.12228
       
  • N‐Alkoxyheterocycles As Irreversible Photooxidants
    • Authors: Zofia M. Wosinska; Faye L. Stump, Rajeev Ranjan, Edward D. Lorance, GeNita N. Finley, Priya P. Patel, Muzamil A. Khawaja, Katie L. Odom, Wolfgang H. Kramer, Ian R. Gould
      Pages: n/a - n/a
      Abstract: Irreversible photooxidation based on N‐O bond fragmentation is demonstrated for N‐methoxyheterocycles in both the singlet and triplet excited state manifolds. The energetic requirements for bond fragmentation are studied in detail. Bond fragmentation in the excited singlet manifold is possible for ππ* singlet states with energies significantly larger than the N‐O bond dissociation energy of ca. 55 kcal/mol. For the nπ* triplet states, N‐O bond fragmentation does not occur in the excited state for orbital overlap and energetic reasons. Irreversible photooxidation occurs in the singlet states by bond fragmentation followed by electron transfer. Irreversible photooxidation occurs in the triplet states via bimolecular electron transfer to the donor followed by bond fragmentation. Using these two sensitization schemes, donors can be irreversibly oxidized with oxidation potentials ranging from ca. 1.6‐2.2 V vs. SCE. The corresponding N‐ethylheterocycles are characterized as conventional reversible photooxidants in their triplet states. The utility of these sensitizers is demonstrated by irreversibly generating the guanosine radical cation in buffered aqueous solution. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-17T09:45:19.267061-05:
      DOI: 10.1111/php.12227
       
  • Chemosensitization of Cancer Cells via Gold Nanoparticle‐Induced
           Cell Cycle Regulation
    • Authors: Megan A. Mackey; Mostafa A. El‐Sayed
      Pages: n/a - n/a
      Abstract: We have previously shown that plasmonic nanoparticles conjugated with nuclear‐targeting and cytoplasm‐targeting peptides (NLS and RGD, respectively) are capable of altering the cell cycle of human oral squamous carcinoma cells (HSC‐3). In the present work, we show that this regulation of the cell cycle can be exploited to enhance the efficacy of a common chemotherapeutic agent, 5‐Fluorouracil, by pre‐treating cells with gold nanoparticles. Utilizing flow cytometry cell cycle analysis, we were able to quantify the 5‐Fluorouracil efficacy as an accumulation of cells in the S phase with a depletion of cells in the G2/M phase. Two gold nanoparticle sizes were tested in this work; 30 nm with a surface plasmon resonance at 530 nm and 15 nm with a surface plasmon resonance at 520 nm. The 30 nm nuclear‐targeted gold nanoparticles (NLS‐AuNPs) showed the greatest 5‐Fluorouracil efficacy enhancement when 5‐Fluorouracil treatment (500 μM, 48 h) is preceded by a 24 h treatment with nanoparticles. In conclusion, we show that nuclear‐targeted 30 nm gold nanoparticles enhance 5‐Fluorouracil drug efficacy in HSC‐3 cells via regulation of the cell cycle, a chemosensitization technique that could potentially be expanded to different cell lines and different chemotherapies. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-16T01:39:07.160068-05:
      DOI: 10.1111/php.12226
       
  • Photochemical Generation of 9H‐Fluorenyl Radicals;
    • Authors: Tatiana Dyblenko; Andrei Chtchemelinine, Ryan Reiter, Ruhul Q. Chowdhury, Alexander Enaya, Hanan Afifi, Rene Fournier, Gabriela Mladenova, Alfred Barry P. Lever, Edward Lee‐Ruff
      Pages: n/a - n/a
      Abstract: A series of 9‐substituted fluorenols and 9,9’‐disubstituted‐9,9’‐bifluorenyls were irradiated to give products derived from fluorenyl radicals. Product distribution was solvent dependent. A TEMPO adduct was isolated from the photoexcitation of 9‐fluorenol. An unusual unsymmetrical 3,9’‐bifluorenyl was observed from the photolysis of 9‐trifluoromethylfluorenol and 9,9’‐di(trifluoromethyl)‐9,9’‐bifluorenyl in more polar or hydrogen‐bonding solvents. The electronic nature of 9‐substituted fluorenyl radicals was probed using theoretical calculations showing the dipolar character of species with electron‐deficient groups. These constitute the first examples of “doubly destabilized” radicals. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-16T01:39:01.928575-05:
      DOI: 10.1111/php.12225
       
  • Photoacclimation responses of the brown macroalga Sargassum cymosum to the
           combined influence of UV radiation and salinity: cytochemical and
           ultrastructural organization and photosynthetic performance
    • Authors: Luz K. Polo; Marthiellen R. L. Felix, Marianne Kreusch, Debora T. Pereira, Giulia B. Costa, Carmen Simioni, Luciane C. Ouriques, Fungyi Chow, Fernanda Ramlov, Marcelo Maraschin, Zenilda L. Bouzon, Éder C. Schmidt
      Pages: n/a - n/a
      Abstract: The photoacclimation responses of the brown macroalga Sargassum cymosum were studied to determine its cytochemical and ultrastructural organization, as well as photosynthetic pigments and performance. S. cymosum was cultivated in three salinities (30, 35 and 40 psu) under four irradiation treatments: PAR‐only, PAR+UVA, PAR+UVB and PAR+UVA+UVB. Plants were exposed to PAR at 70 μmol photons m‐2 s‐1, PAR+UVB at 0.35 Wm‐2 and PAR+UVA at 0.70 W m‐2 for 3 h per day during 7 days in vitro. Growth rate was not significantly affected by any type of radiation or salinity. The amount of pigments in S. cymosum was significantly influenced by the interaction of salinity and radiation treatments. Compared to PAR‐only, UVR treatments modified the kinetics patterns of the photosynthesis/irradiance curve. After exposure to UVR, S. cymosum increased cell wall thickness and the presence of phenolic compounds. The number of mitochondria increased, while the number of chloroplasts showed few changes. Although S. cymosum showed insensitivity to changes in salinity, it can be concluded that samples treated under four irradiation regimes showed structural changes, which were more evident, but not severe, under PAR+UVB treatment. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-14T01:19:17.111816-05:
      DOI: 10.1111/php.12224
       
  • Inactivation of Bacteriophage Infecting Bacteroides Strain GB124 Using
           UV‐B Radiation
    • Authors: David Diston; James E. Ebdon, Huw D. Taylor
      Pages: n/a - n/a
      Abstract: UV‐B radiation (280‐320 nm) has long been associated with the inactivation of micro‐organisms in the natural environment. Determination of the environmental inactivation kinetics of specific indicator organisms [used as tools in the field of microbial source tracking (MST)] is fundamental to their successful deployment, particularly in geographical regions subject to high levels of solar radiation. Phage infecting Bacteroides fragilis host strain GB124 (B124 phage) have been demonstrated to be highly specific indicators of human faecal contamination, but to date, little is known about their susceptibility to UV‐B radiation. Therefore, B124 phage (n = 7) isolated from municipal wastewater effluent, were irradiated in a controlled laboratory environment using UV‐B collimated beam experiments. All B124 phage suspensions possessed highly similar first order log‐linear inactivation profiles and the mean fluence required to inactivate phage by 4‐log10 was 320 mJ/cm2. These findings suggest that phage infecting GB124 are likely to be inactivated when exposed to the levels of UV‐B solar radiation experienced in a variety of environmental settings. As such, this may limit the utility of such methods for determining more remote inputs of faecal contamination in areas subject to high levels of solar radiation. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-12T13:01:13.749575-05:
      DOI: 10.1111/php.12223
       
  • Triplet–Triplet Energy Transfer from a UV‐A Absorber
           Butylmethoxydibenzoylmethane to UV‐B Absorbers
    • Authors: Azusa Kikuchi; Nozomi Oguchi‐Fujiyama, Kazuyuki Miyazawa, Mikio Yagi
      Pages: n/a - n/a
      Abstract: The phosphorescence decay of a UV‐A absorber, 4‐tert‐butyl‐4’‐methoxydibenzolymethane (BMDBM) has been observed following a 355 nm laser excitation in the absence and presence of UV‐B absorbers, 2‐ethylhexyl 4‐methoxycinnamate (octyl methoxycinnamate, OMC) and octocrylene (OCR) in ethanol at 77 K. The lifetime of the lowest excited triplet (T1) state of BMDBM is significantly reduced in the presence of OMC and OCR. The observed quenching of BMDBM triplet by OMC and OCR suggests that the intermolecular triplet–triplet energy transfer occurs from BMDBM to OMC and OCR. The T1 state of OCR is nonphosphorescent or very weakly phosphorescent. However, we have shown that the energy level of the T1 state of OCR is lower than that of the enol form of BMDBM. Our methodology of energy‐donor phosphorescence decay measurements can be applied to the study of the triplet–triplet energy transfer between UV absorbers even if the energy acceptor is nonphosphorescent. In addition, the delayed fluorescence of BMDBM due to triplet–triplet annihilation was observed in the BMDBM–OMC and BMDBM–OCR mixtures in ethanol at 77 K. Delayed fluorescence is one of the deactivation processes of the excited states of BMDBM under our experimental conditions. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-11T08:49:28.503787-05:
      DOI: 10.1111/php.12222
       
  • Characterization of the triplet state of Tanshinone IIA and its reactivity
           by laser flash photolysis
    • Authors: Kun Li; Qin Zhang, Mei Wang, Rongrong Zhu, Xiaoyu Sun, Xianzheng Wu, Shi‐Long Wang
      Pages: n/a - n/a
      Abstract: Tanshinone IIA (Tan IIA) has the properties of cardiovascular protection, anti‐inflammation, anti‐oxidation, and anti‐cancer. Its light‐induced instability has drawn our interests in its photochemistry. Therefore, laser flash photolysis herein was used to investigate the transient photochemistry of Tan IIA. Our results show that direct photo‐excitation by 355 nm laser pulses or photosensitization by energy transfer can lead to the formation of the triplet state of Tan IIA (3Tan IIA*). The triplet absorption spectrum and molar absorption coefficient, and ISC quantum yield were determined. Self‐quenching of 3Tan IIA* by its ground state was identified as an auto‐oxidation reaction. 3Tan IIA* was proved to react quickly with N, N‐dimethylaniline, tert‐butylhydroquinone and propyl gallate via electron transfer with the diffusion‐controlled rate constants. One of the products with maximum absorption around 390 nm was assigned to the radical anion of Tan IIA. Our results indicate that 3Tan IIA* is a reactive transient species and can be generated by photosensitization or direct photoexcitation. According to our results, the possible role of Tan IIA as a photosensitizer to induce potential phototoxicity via Type II pathway in the presence of O2 can be predicted. This article is protected by copyright. All rights reserved.
      PubDate: 2013-12-10T10:07:37.596649-05:
      DOI: 10.1111/php.12220
       
  • Analgesic Effect of Light‐Emitting Diode (LED) Therapy at
           Wavelengths of 635 and 945 nm on Bothrops moojeni Venom‐Induced
           Hyperalgesia
    • Authors: Nikele Nadur‐Andrade; Stella R. Zamuner, Elaine F. Toniolo, Carlos J. Lima, José C. Cogo, Camila S. Dale
      Pages: n/a - n/a
      Abstract: Envenoming induced by Bothrops snakes is characterized by drastic local tissue damage involving hemorrhage, myonecrosis and proeminent inflammatory and hyperalgesic response. The most effective treatment is antivenom therapy, which is ineffective in neutralizing the local response. Herein, it was evaluated the effectiveness of light‐emitting diode (LED) at wavelengths of 635 and 945 nm in reducing inflammatory hyperalgesia induced by Bothrops moojeni venom (BmV) in mice, produced by an subplantar injection of BmV (1 μg). Mechanical hyperalgesia and allodynia were assessed by von Frey filaments at 1, 3, 6 and 24 h after venom injection. The site of BmV injection (1.2 cm2) was irradiated by LEDs at 30 min and 3 h after venom inoculation. Both 635 nm (110 mW, fluence of 3.76 J/cm2 and 41 s of irradiation time) and 945 nm (120 mW, fluence of 3.8 J/cm2 and 38 s of irradiation time) LED inhibited mechanical allodynia and hyperalgesia of mice alone or in combination with antivenom treatment, even when the symptoms were already present. The effect of phototherapy in reducing local pain induced by BmV should be considered as a novel therapeutic tool for the treatment of local symptoms induced after bothropic snake bites. The effectiveness of LED at wavelengths of 635 and 945 nm, in reducing mechanical inflammatory hyperalgesia and allodynia induced by Bothrops moojeni venom (BmV) in mice, produced by a subplantar injection of BmV (1 μg) was evaluated at 1, 3, 6 and 24 h after BmV injection. The site of BmV injection (1.2 cm2) was irradiated by LEDs at 30 min and 3 h after BmV inoculation. Both 635 and 945 nm LED inhibited mechanical allodynia and hyperalgesia of mice alone or in combination with antivenom treatment, even when the symptoms were already present.
      PubDate: 2013-11-28T05:30:27.966336-05:
      DOI: 10.1111/php.12189
       
  • Role of Ozone in UV‐C Disinfection, Demonstrated by Comparison
           between Wild‐Type and Mutant Conidia of Aspergillus niger
    • Authors: Jing Liu; Lin Zhou, Ji‐Hong Chen, Wang Mao, Wen‐Jian Li, Wei Hu, Shu‐Yang Wang, Chun‐Ming Wang
      Pages: n/a - n/a
      Abstract: This study aimed to investigate the tolerance of a melanized wild‐type strain of Aspergillus niger (CON1) and its light‐colored mutant (MUT1) to UV‐C light and the concomitantly generated ozone. Treatments were segregated into four groups based on whether UV irradiation was used and the presence or absence of ozone: (‐UV, ‐O3), (‐UV, +O3), (+UV, ‐O3) and (+UV, +O3). The survival of CON1 and MUT1 conidia under +UV decreased as the exposure time increased, with CON1 showing greater resistance to UV irradiation than MUT1. Ozone induced CON1 conidium inactivation only under conditions of UV radiation exposure. While, the inactivation effect of ozone on MUT1 was always detectable regardless of the presence of UV irradiation. Furthermore, the CON1 conidial suspension showed lower UV light transmission than MUT1 when examined at the same concentration. Compared with the pigment in MUT1, the melanin in CON1 exhibited more potent radical‐scavenging activity and stronger UV absorbance. These results suggested that melanin protected A. niger against UV disinfection via UV screening and free radical scavenging. The process by which UV‐C disinfection induces a continual decrease in conidial survival suggests that UV irradiation and ozone exert a synergistic fungicidal effect on A. niger prior to reaching a plateau. This article is protected by copyright. All rights reserved.
      PubDate: 2013-11-27T11:30:55.30919-05:0
      DOI: 10.1111/php.12217
       
  • Photosensitized Damage Inflicted On Plasma Membranes Of Live Cells By An
           Extracellular Generator Of Singlet Oxygen ‐ A Linear Dependence Of A
           Lethal Dose On Light Intensity
    • Authors: Mirosław Zarębski; Magdalena Kordon, Jurek W. Dobrucki
      Pages: n/a - n/a
      Abstract: We describe a study of the influence of a dose rate, i.e. light intensity or photon flux, on the efficiency of induction of a loss of integrity on plasma membranes of live cells in culture. The influence of a photon flux on the size of the light dose, which was capable of causing lethal effects, was measured in an experimental system where singlet oxygen was generated exclusively outside of live cells by ruthenium(II) phenantroline complex. Instantaneous, sensitive detection of a loss of integrity of a plasma membrane was achieved by fluorescence confocal imaging of the entry of this complex into a cell interior. We demonstrate that the size of the lethal dose of light is directly proportional to the intensity of the exciting light. Thus, the probability of a photon of the exciting light inflicting photosensitised damage on plasma membranes diminishes with increasing density of the incident photons. This article is protected by copyright. All rights reserved.
      PubDate: 2013-11-26T11:25:30.678563-05:
      DOI: 10.1111/php.12216
       
  • Why is Rose Bengal more phototoxic to fibroblasts in vitro than in
           vivo?
    • Authors: Min Yao; Chuan Gu, Francis J. Doyle, Robert W. Redmond, Irene E. Kochevar
      Pages: n/a - n/a
      Abstract: Photosensitized protein crosslinking has been recently developed to seal wounds and strengthen tissue. Although the photosensitizing dye, Rose Bengal (RB), is phototoxic to cultured cells, cytotoxicity does not accompany RB‐photosensitized tissue repair in vivo. We investigated whether the environment surrounding cells in tissue or the high irradiances used for photo‐crosslinking inhibited RB phototoxicity. Fibroblasts (FB) grown within collagen gels to mimic a tissue environment and monolayer cultured FB were treated with RB (0.01‐1 mM) and the high 532 nm laser irradiances used in vivo for tissue repair (0.10‐0.50 W/cm2). Monolayer FB were substantially more sensitive to RB photosensitization: the LD50 was >200‐fold lower than that in collagen gels. Collagen gel protection was associated with increased Akt phosphorylation, a pro‐survival pathway. RB phototoxicity in collagen gels was 25‐fold greater at low (0.030 W/cm2) that at high (0.50 W/cm2) irradiances. Oxygen depletion at high irradiance only partially accounted for the irradiance dependence of phototoxicity since replacing air with nitrogen only increased the LD50 by 4‐fold in monolayers. These results indicate that the lack of RB phototoxicity during in vivo tissue repair results from up‐regulation of pro‐survival pathways in tissue cells, oxygen depletion and irradiance‐dependent RB photochemistry. This article is protected by copyright. All rights reserved.
      PubDate: 2013-11-25T00:12:51.137829-05:
      DOI: 10.1111/php.12215
       
  • 1H NMR Study of Hydrogen Abstraction in Model Compound Mimics of Polymers;
    • Authors: Jeffrey R. Lancaster; Rachael Smilowitz, Nicholas J. Turro, Jeffrey T. Koberstein
      Pages: n/a - n/a
      Abstract: Small molecules representing common synthetic polymers were subjected to photochemically‐induced hydrogen abstraction by benzophenone. Reactions were monitored using 1H NMR to query the factors that influence preferential abstraction of protons in unique chemical environments. Differences in bond dissociation energies do not fully explain the observed hydrogen abstraction preferences. To that end, we identify contributions to abstraction from pre‐reactive complexation, radical stability, steric effects, and charge transfer effects. Using representative small molecule model compounds in lieu of polymeric materials is a novel approach to understanding photochemical reaction in polymers, however it cannot probe the contributions of macromolecular effects – e.g. polymer rigidity or sidechain and backbone mobility – to preferential hydrogen abstraction. This article is protected by copyright. All rights reserved.
      PubDate: 2013-11-21T02:30:20.585922-05:
      DOI: 10.1111/php.12214
       
  • Reflectance and Cyclic Electron Flow as an indicator of drought stress in
           Cotton (Gossypium hirsutum)
    • Authors: Ruchi Singh; Jishnu Naskar, Uday V. Pathre, Pramod A. Shirke
      Pages: n/a - n/a
      Abstract: The response and the functioning of the photosynthetic machinery of cotton, Gossypium hirsutum during water stress was studied by, leaf optical properties, linear (ETRII) and cyclic electron flow and chlorophyll a fluorescence. We observed that in G. hirsutum, during water limitation, Chlorophyll b showed the best correlation with reflectance at 731nm and is a better indicator of drought. Fv/Fm was observed to be very insensitive to mild water stress. However, during severe water stress the leaves exhibit considerable inhibition in Fv/Fm and an increase in anthocyanin levels by about 20 fold. Cyclic electron flow was very responsive to mild water stress. The mild drought stress caused large decrease in the ability of the leaves to utilize the light energy. PSI and PSII is protected from photo‐inhibition by high cyclic electron flow and NPQ under mild water stress. While during severe drought stress, linear electron flow showed a sharp decrease in comparison to cyclic electron flow. Cyclic electron flow play a major role in G. hirsutum leaves during mild as well as under severe water stress condition and is thus a good indicator of water stress. This article is protected by copyright. All rights reserved.
      PubDate: 2013-11-19T00:26:15.145026-05:
      DOI: 10.1111/php.12213
       
  • Singlet Oxygen Generation by Cyclometalated Complexes and Applications
    • Authors: David Ashen‐Garry; Matthias Selke
      Pages: n/a - n/a
      Abstract: While cyclometalated complexes have been extensively studied for optoelectronic applications, these compounds also represent a relatively new class of photosensitizers for the production of singlet oxygen. Thus far, singlet oxygen generation from cyclometalated Ir and Pt complexes has been studied in detail. In this review, photophysical data for singlet oxygen generation from these complexes is presented, and the mechanism of 1O2 generation is discussed, including evidence for singlet oxygen generation via an electron transfer mechanism for some of cyclometalated Ir complexes. The period from the first report of singlet oxygen generation by a cyclometalated Ir complex in 2002 through August 2013 is covered in this review. This new class of singlet oxygen photosensitizers may prove to be rather versatile due to the ease of substitution of ancillary ligands without loss of activity. Several cyclometalated complexes have been tethered to zeolites, polystyrene, or quantum dots. Applications for photooxygenation of organic molecules, including “traditional” singlet oxygen reactions (ene reaction, [4+2] and [2+2] cycloadditions) as well as oxidative coupling of amines are presented. Potential biomedical applications are also reviewed. This article is protected by copyright. All rights reserved.
      PubDate: 2013-11-08T03:16:22.891193-05:
      DOI: 10.1111/php.12211
       
  • Inactivation of Bacillus subtilis Spores Using Various Combinations of
           Ultraviolet Treatment with Addition of Hydrogen Peroxide
    • Authors: Yiqing Zhang; Yongji Zhang, Lingling Zhou, Chaoqun Tan
      Pages: n/a - n/a
      Abstract: This study aims at comparing the inactivation of Bacillus subtilis spores by various combinations of ultraviolet (UV) treatment and hydrogen peroxide (H2O2) addition. The combinations included sequential (UV‐H2O2, H2O2‐UV) and simultaneous (UV/H2O2) processes. Results showed that B. subtilis spores achieved a certain inactivation effect through UV treatment. However, hardly any inactivation effect by H2O2 alone was observed. H2O2 had a significant synergetic effect when combined with UV treatment, while high irradiance and H2O2 concentration both favored the reaction. When treated with 0.60 mM H2O2 and 113.0 μW/cm2 UV irradiance for 6 min, the simultaneous UV/H2O2 treatment showed significantly improved disinfection effect (4.13 log) compared to that of UV‐H2O2 (3.03 log) and H2O2‐UV (2.88 log). The relationship between the inactivation effect and the exposure time followed a typical pseudo‐first‐order kinetics model. The pseudo‐first‐order rate constants were 0.478, 0.447 and 0.634 min−1, for the UV‐H2O2, H2O2‐UV and UV/H2O2 processes, respectively, further confirming the optimal disinfection effect of the UV/H2O2 process. The disinfection could be ascribed to the OH radicals, as verified by the level of para‐chlorobenzoic acid (pCBA). This article is protected by copyright. All rights reserved.
      PubDate: 2013-11-08T03:16:15.847461-05:
      DOI: 10.1111/php.12210
       
  • Antimicrobial Photodynamic Efficiency of Novel Cationic Porphyrins towards
           Periodontal Gram‐positive and Gram‐negative Pathogenic
           Bacteria
    • Authors: Chandra Sekhar Prasanth; Suneesh C. Karunakaran, Albish K. Paul, Vesselin Kussovski, Vanya Mantareva, Danaboyina Ramaiah, Leslie Selvaraj, Ivan Angelov, Latchezar Avramov, Krishnankutty Nandakumar, Narayanan Subhash
      Pages: n/a - n/a
      Abstract: The Gram‐negative Actinobacillus actinomycetemcomitans and Fusobacterium nucleatum are major causative agents of aggressive periodontal disease. Due to increase in the number of antibiotic‐resistant bacteria, antimicrobial Photodynamic therapy (aPDT) seems to be a plausible alternative. In the present work, photosensitization was performed on Gram‐positive and Gram‐negative bacteria in pure culture using new‐age cationic porphyrins, namely meso‐imidazolium substituted porphyrin derivative (ImP) and pyridinium substituted porphyrin derivative (PyP). The photophysical properties of both the sensitizers including absorption, fluorescence emission, quantum yields of the triplet excited states and singlet oxygen generation efficiencies were evaluated in the context of aPDT application. The studied porphyrins exhibited high ability to accumulate into bacterial cells with complete penetration into early stage biofilms. As compared to ImP, PyP was found to be more effective for photoinactivation of bacterial strains associated with periodontitis, without any signs of dark toxicity, owing to its high photocytotoxicity. This article is protected by copyright. All rights reserved.
      PubDate: 2013-10-27T07:21:05.555272-05:
      DOI: 10.1111/php.12198
       
  • Formation and Repair of UV‐induced Dimeric DNA Pyrimidine Lesions
    • Authors: Andrea Christa Kneuttinger; Gengo Kashiwazaki, Stefan Prill, Korbinian Heil, Markus Müller, Thomas Carell
      Pages: n/a - n/a
      Abstract: Direct repair of UV‐induced DNA lesions represents an elegant method for many organisms to deal with these highly mutagenic and cytotoxic compounds. Although the participating proteins are structurally well investigated, the exact repair mechanism of the photolyase enzymes remains a vivid subject of current research. In this review, we summarize and highlight the recent contributions to this exciting field. This article is protected by copyright. All rights reserved.
      PubDate: 2013-10-25T11:35:42.6898-05:00
      DOI: 10.1111/php.12197
       
  • Implication of ultraviolet light in the etiology of uveal melanoma: A
           review
    • Authors: Justin D. Mallet; Sébastien P. Gendron, Marie‐Catherine Drigeard Desgarnier, Patrick J. Rochette
      Pages: 15 - 21
      Abstract: Uveal melanoma is the most frequent intraocular cancer and the second most common form of melanoma. It metastasizes in half of the patients and the prognostic is poor. Although ultraviolet (UV) radiation is a proven risk factor for skin melanoma, the role of UV light in the etiology of uveal melanoma is still contradictory. We have compared epidemiological and genetic evidences of the potential role of UV radiation in uveal melanoma with data on cutaneous melanoma. Even though frequently mutated genes in skin melanoma (e.g. BRAF) differ from those found in uveal melanoma (i.e. GNAQ, GNA11), their mutation pattern bears strong similarities. Furthermore, we provide new results showing that RAC1, a gene recently found harboring UV‐hallmark mutation in skin melanoma, is also mutated in uveal melanoma. This article aims to review the work done in the last decades to understand the etiology of uveal melanoma and discuss new avenues, which shed some light on the potential role of UV exposure in uveal melanoma. Uveal melanoma is the most frequent intraocular cancer and the second most common form of melanoma after cutaneous. The evidences are contradictory about the role of ultraviolet (UV) light in the etiology of in uveal melanoma. We have compared epidemiological and genetic evidences of the potential role of UV radiation in uveal melanoma with data on cutaneous melanoma. We have reviewed the work done in the last decades in order to understand the etiology of uveal melanoma and discuss new avenues, which shed some light on the potential role of UV exposure in uveal melanoma.
      PubDate: 2013-09-30T09:26:23.444157-05:
      DOI: 10.1111/php.12161
       
  • Photophysical Properties of Lanthanide (Eu3+, Tb3+) Hybrid Soft Gels of
           Double Functional Linker of Ionic Liquid–Modified Silane
    • Authors: Qiu‐Ping Li; Bing Yan
      Pages: 22 - 28
      Abstract: Four kinds of luminescent hybrid soft gels have been assembled by introducing the lanthanide (Eu3+, Tb3+) tetrakis β‐diketonate into the covalently bonded imidazolium‐based silica through electrostatic interactions. Here, the imidazolium‐based silica matrices are prepared from imidazolium‐derived organotriethoxysilanes by the sol–gel process, in which the imidazolium cations are strongly anchored within the silica matrices while anions can still be exchanged following application for functionalization of lanthanide complexes. The photoluminescence measurements indicated that these hybrid soft gels exhibit characteristic red and green luminescence originating from the corresponding ternary lanthanide ions (Eu3+, Tb3+). Further investigation of photophysical properties reveals that these soft gels have inherited the outstanding luminescent properties from the lanthanide tetrakis β‐diketonate complexes such as strong luminescence intensities, long lifetimes and high luminescence quantum efficiencies. Ternary lanthanide luminescent hybrid soft gels Gel‐Im+[LaL4]− were prepared by linking the europium/terbium tetrakis β‐diketonate complexes into the silicon framework, which provides a representative method to assemble lanthanide‐functionalized porous materials with chemical bonds.
      PubDate: 2013-09-03T07:23:07.043139-05:
      DOI: 10.1111/php.12149
       
  • Investigation on Photophysical Properties of
           D–π–A–π–D‐Type
           Fluorenone‐Based Linear Conjugated Oligomers by Using Femtosecond
           Transient Absorption Spectroscopy
    • Authors: Tian‐hao Huang; Ying‐hui Wang, Zhi‐hui Kang, Jin‐bo Yao, Ran Lu, Han‐zhuang Zhang
      Pages: 29 - 34
      Abstract: The effects of π‐spacer and electron donor groups on the photophysical behaviors of fluorenone‐based linear conjugated oligomers have been systemically investigated. Solvent‐dependent steady‐state measurements exhibit that the fluorene vinylene (FV) spacer and the electron‐donating ability of donor group are able to modulate the spectral features of oligomers and the fluorescence quantum yield could decrease with the increasing of the solvent polarity. Meanwhile, quantum chemical calculation simulates their absorption spectra, and analyzes their electron transition components simultaneously. The transient absorption measurements focus on the photoexcitation dynamics of these oligomers in the toluene solution, which show that an intramolecular charge transfer state exists in the relaxation process of excited states, and its generation process could accelerate with the introduction of FV spacer and the enhancement of donor strength. Dynamic mechanism of fluorenone‐based linear conjugated oligomers.
      PubDate: 2013-09-16T02:00:28.924925-05:
      DOI: 10.1111/php.12154
       
  • Theoretical Study of Fluorescence Spectra Utilizing the pKa Values of
           Acids in Their Excited States
    • Authors: Miyabi Hiyama; Hidefumi Akiyama, Kenta Yamada, Nobuaki Koga
      Pages: 35 - 44
      Abstract: Assignment of the fluorescence spectrum of firefly luciferin in aqueous solutions was achieved by utilizing not only emission energies but also theoretical absorption spectra and relative concentrations as estimated by pKa values. Calculated Gibbs free energies were utilized to estimate pKa values. These pKa values were then corrected by employing the experimental results. It was previously thought that the main peak near 550 nm observed in the experimental fluorescence spectra at all pH values corresponds to emission from the first excited state of the luciferin dianion [Ando et al. (2010) Jpn. J. Appl. Phys. 49, 117002–117008]. However, we found that the peak near 550 nm at low pH corresponds to emission from the first excited state of the phenolate monoanion of luciferin. Furthermore, we found that the causes of the red fluorescence at pH 1–2 are not only the emission from phenol monoanion but also the emission from the protonated species at nitrogen atom in the thiazoline ring of dianion. With the help of theoretical pKa values in the first excited states the experimental fluorescence spectra of firefly luciferin and its conjugate acids and bases in solution with various pH values were successfully assigned.
      PubDate: 2013-09-16T02:00:26.091271-05:
      DOI: 10.1111/php.12156
       
  • Investigation on “Excimer” Formation Mechanism of Linear
           Oligofluorenes‐Functionalized Anthracenes by Using Transient
           Absorption Spectroscopy
    • Authors: Ying‐Hui Wang; Lu Zou, Zhi‐Hui Kang, Cheng Qian, Fuyin Wang, Yu‐Guang Ma, Ran Lu, Hong Ji, Han‐Zhuang Zhang
      Pages: 45 - 50
      Abstract: We study the photophysical characters of two oligofluorenes‐functionalized anthracenes molecules with different fluorine‐vinylene (FV) units, which exhibits that “excimer” state appears in the solution after photoexcitation. The dynamic data shows that two mechanisms are responsible for the generation of “excimer”. The fast one is controlled by the arene‐arene interaction between molecules and the slow one is influenced by the diffusion motion of molecules. Increasing the number of FV units may suppress the DM‐dependent “excimer” and enhance the yield of intrinsic fluorescence, which finally improves the fluorescence property of molecules in solution. The “excimer” generation mechanisms of oligofluorenes‐functionalized anthracenes molecules with fluorine‐vinylene (FV) units in solution were studied. The diffusion of molecule (DM) and arene‐arene interaction (A‐A I) could be responsible for the formation processes of “excimer”. As the number of FV units increases, the DM‐dependent “excimer” generation process could be restrained, but the A‐A I dependent formation path may be enhanced. Fortunately, the total optical property of the linear oligofluorenes‐functionalized anthracenes molecules could be improved due to the enhancement of intrinsic fluorescence quantum yield as the FV units increase.
      PubDate: 2013-11-14T23:52:03.963591-05:
      DOI: 10.1111/php.12159
       
  • Synthesis, Characterization and Photocatalytic Activity of
           Mg‐Impregnated ZnO–SnO2 Coupled Nanoparticles
    • Authors: Mohammad A. Behnajady; Yasamin Tohidi
      Pages: 51 - 56
      Abstract: ZnO–SnO2 nanoparticles were prepared by coprecipitation method; then Mg, with different molar ratios and calcination temperatures, was loaded on the coupled nanoparticles by impregnation method. The synthesized nanoparticles were characterized by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X‐ray spectroscopy (EDX), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and Brunauer–Emmett–Teller (BET) techniques. Based on XRD results, the ZnO–SnO2 and Mg/ZnO–SnO2 nanoparticles were made of ZnO and SnO2 nanocrystallites. According to DRS spectra, the band gap energy value of 3.13 and 3.18 eV were obtained for ZnO–SnO2 and Mg/ZnO–SnO2 nanoparticles, respectively. BET analysis revealed a Type III isotherm with a microporous structure and surface area of 32.051 and 49.065 m2 g−1 for ZnO–SnO2 and Mg/ZnO–SnO2, respectively. Also, the spherical shape of nanocrystallites was deduced from TEM and FESEM images. The photocatalytic performance of pure ZnO–SnO2 and Mg/ZnO–SnO2 was analyzed in the photocatalytic removal of methyl orange (MO). The results indicated that Mg/ZnO–SnO2 exhibited superior photocatalytic activity to bare ZnO–SnO2 photocatalyst due to high surface area, increased MO adsorption and larger band gap energy. Maximum photocatalytic activity of Mg/ZnO–SnO2 nanoparticles was obtained with 0.8 mol% Mg and calcination temperature of 350°C. The coupled and Mg impregnated ZnO–SnO2 nanoparticles were prepared by co‐precipitation method with various Mg molar ratios and calcination temperatures. With Mg impregnation, the band gap energy of ZnO–SnO2 nanoparticles increases by 0.05 eV, exhibiting a blue shift. Mg/ZnO–SnO2 nanoparticles indicated a better performance than pure ZnO–SnO2 nanoparticles.
      PubDate: 2013-09-30T09:33:56.41931-05:0
      DOI: 10.1111/php.12164
       
  • One‐Pot Fabrication of RGO–Ag3VO4 Nanocomposites by in situ
           Photoreduction using Different Sacrificial Agents: High Selectivity Toward
           Catechol Synthesis and Photodegradation Ability
    • Authors: Dipti P. Das; Alaka Samal, Jasobanta Das, Ajit Dash, Hariom Gupta
      Pages: 57 - 65
      Abstract: Weak photon absorption and fast carrier kinetics in graphene restrict its applications in photosensitive reactions. Such restrictions/limitations can be overcome by covalent coupling of another photosensitive nanostructure to graphene, forming graphene‐semiconductor nanocomposites. Herein, we report one‐pot synthesis of RGO–Ag3VO4 nanocomposites using various sacrificial agents like ethanol, methanol, propanol and ethylene glycol (EG) under visible light illumination. The Raman spectral analysis and 13C MAS NMR suggest ethanol to be the best sacrificial agent among those studied. Thermal analysis studies, further, confirm the stability of the synthesized nanocomposite with ethanol as sacrificial agent. In view of this, the activity toward dye degradation was focused over the composites prepared via ethanol as sacrificial agent. It was observed and proved that cationic dyes could be degraded quantitatively and swiftly compared to anionic dyes (37.79%) in 1.5 h. This suggests that the surface of the nanocomposites is anionic as partial reduction takes place during synthesis process. In case of mixed dye degradation process, it was noticed that the presence of cationic dye doubles the degradation of anionic dye. The activity of these synthesized nanocomposites is more than five‐fold toward the phototransformation of phenol and photodegradation of textile dyes under visible light illumination. One‐pot synthesis of RGO–Ag3VO4 nanocomposites using various sacrificial agents like ethanol, methanol, propanol and ethylene glycol (EG) under visible light illumination. The activity of these synthesized nanocomposites is more than five‐fold toward the photohydroxylation of phenol and photodegradation of textile dyes under visible light (VISL) illumination.
      PubDate: 2013-10-18T04:08:49.707415-05:
      DOI: 10.1111/php.12172
       
  • The Role of the Relative Dye/Photocatalyst Concentration in TiO2 Assisted
           Photodegradation Process
    • Authors: Vagner R. Mendonça; Henrique A. J. L. Mourão, Andréa R. Malagutti, C. Ribeiro
      Pages: 66 - 72
      Abstract: Despite photocatalytic degradation is studied generally focusing the catalyst, its interaction with the contaminant molecule plays a fundamental role in the efficiency of that process. Then, we proposed a comparative study about the photodegradation of two well‐known dyes, with different acidity/basicity – Methylene Blue (MB) and Rhodamine B (RhB), catalyzed by TiO2 nanoparticles, varying both dye and photocatalyst concentrations. The results showed that the amphoteric character of MB molecules, even in a range of concentration of 5.0–10.0 mg L−1, did not imply in pH variation in solution. Therefore, it did not affect the colloidal behavior of TiO2 nanoparticles, independent of the relative dye/catalyst concentration. The acid–base character of RhB influenced the resultant pH of the solution, implicating in different colloidal behavior of the nanoparticles and consequently, in different degradation conditions according to dye concentration. As the isoelectric point of TiO2 is between the pH range of the RhB solutions used in this study, from 1.0 to 7.5 mg L−1, the resultant pH was the key factor for degradation conditions, from a well dispersed to an agglomerated suspension. Plot presenting the relation between photoinduced RhB photodegradation rate constant (k* = k'/[TiO2]) as a function of TiO2 photocatalyst and Rhodamine B initial concentration.
      PubDate: 2013-10-21T00:50:26.828846-05:
      DOI: 10.1111/php.12175
       
  • Substituent Effect on the Photolability of
           4‐Aryl‐1,4‐Dihydropyridines
    • Authors: Cristóbal García; Karina Cabezas, Santi Nonell, Luis J. Núñez‐Vergara, Javier Morales, Germán Günther, Nancy Pizarro
      Pages: 73 - 78
      Abstract: The electronic nature of substituents attached to the 4‐aryl moiety of 1,4‐dihydropyridines strongly affects the photophysical and photochemical behavior of these family of compounds. The presence of an electron donor substituent on the 4‐aryl moiety (or the absence of electron‐withdrawing ones) modifies the luminescence lifetimes (τ 
      PubDate: 2013-10-30T06:11:17.306759-05:
      DOI: 10.1111/php.12178
       
  • Photochemical Behavior and Photolysis of Protonated Forms of Levofloxacin
    • Authors: Anna Polishchuk; Tatyna Emelina, Emilya Karaseva, Oana Cramariuc, Vladimir Chukharev, Vladimir Karasev
      Pages: 79 - 84
      Abstract: The effect of intermolecular proton transfer on the spectral properties of levofloxacin in the ground and excited electronic states was studied. The preferred direction of possible protolytic reactions induced by UV irradiation in this compound was studied. It was found that the proton transfer processes have a considerable effect on the capability of the compound to emit light and occur on the nanosecond timescale. The photochemical reactions of the tree forms of levofloxacin (pH: 4.0, 7.0, 10.0) were studied by laser flash photolysis and product studies. Irradiation at pH 4 yielded a pulse and transient (λmax = 395, 515, 575 nm) assigned to the protonated triplet. Irradiation at pH 7 yielded a transient species (λmax = 525, 610 nm) assigned to the neutral form. Protonation of the anionic singlet excited state was also observed (λmax = 440, 570, 680 nm). The preferred direction of possible protolytic reactions induced by UV irradiation in fluoroquinolones at different pH of solutions was studied. It was found that the proton transfer processes have a considerable effect on the capability of the compound to emit light and occur on the nanosecond timescale. The photochemical reactions of the three protolytic forms of levofloxacin were studied by laser flash photolysis.
      PubDate: 2013-09-13T23:47:21.138513-05:
      DOI: 10.1111/php.12152
       
  • Amplified Production of Singlet Oxygen in Aqueous Solution Using Metal
           Enhancement Effects
    • Authors: Sara M. Mooi; Belinda Heyne
      Pages: 85 - 91
      Abstract: Studies involving metal enhancement effects have gained popularity, and enhancement of fluorescence due to the close proximity of a dye molecule to a metal nanoparticle is well documented. Although enhancement of singlet oxygen production by metal has been reported, studies are relatively scarce and so far only stationary silver island films have been proven to be adequate to do so. Herein, we describe the synthesis and characterization of core–shell nanoparticles on which a photosensitizer acting as source of singlet oxygen has been covalently attached to the nanoparticle surface. As a proof of concept, silver nanoparticles with a diameter around 68 nm were chosen as the metallic core, and were coated by a silica shell of about 22 nm in thickness. The silica shell plays a dual role as a spacer and a medium onto which the photosensitizer, rose bengal (RB), has been covalently attached. These novel core–shell nanoparticles allow for the amplification of singlet oxygen production by 3.8 times, which is similar to the amplification found for RB in proximity of silver island films. Silver‐silica core‐shell nanoparticles, on to which rose bengal has been covalently attached to the shell, have been synthesized and conventionally characterized. These novel core‐shell nanoparticles allow for an amplification of singlet oxygen production by 3.8 times in aqueous solution.
      PubDate: 2013-10-21T00:57:30.105118-05:
      DOI: 10.1111/php.12176
       
  • Photoreaction of Ketoprofen with Tryptophan and Tyrosine in Phosphate
           Buffer Solution
    • Authors: Mio Shinoda; Tasuku Isozaki, Tadashi Suzuki
      Pages: 92 - 98
      Abstract: Reaction of excited ketoprofen (KP) with tryptophan (Trp) and tyrosine (Tyr) in a phosphate buffer solution was studied by the transient absorption spectroscopy. Both amino acids, which would interact with KP in bovine serum albumin [Monti, S. [2009] Phys. Chem. Chem. Phys., 11, 9104–9113], accelerated the proton transfer reaction to yield 3‐ethylbenzophenone ketyl biradical (EBPH) from KP carbanion, which was produced by photoexcitation of KP− through decarboxylation. By means of the actinometry method with benzophenone, the reaction quantum yield was successfully estimated to be fairly large, and Trp, Tyr, DOPA and 4‐methylphenol were found to be a good proton donor for the carbanion. The formation rate constants of EBPH by the amino acids (kr) were also determined to be (2.7 ± 0.1) × 109 M−1s−1 for Trp and (7.8 ± 0.4) × 108 M−1s−1 for Tyr, which were larger than those by basic amino acids and dipeptides reported. The reason for the highly efficient proton transfer reaction with Trp and Tyr would be explained by difference of the activation energy for the reaction. These results suggest that the proton transfer should be a key process for an initial photoreaction of KP with a protein, causing photosensitization in vivo. Reaction of excited ketoprofen (KP) with tryptophan (Trp) and tyrosine (Tyr) in a phosphate buffer solution was studied by the transient absorption spectroscopy. Both amino acids accelerated the proton transfer reaction to yield 3‐ethylbenzophenone ketyl biradical from KP carbanion. The reaction quantum yield was successfully estimated, and Trp and Tyr were found to be a good proton donor. The highly efficient proton transfer reaction can be explained by difference of the activation energy for the reaction. The proton transfer should be a key reaction of KP in a protein, causing photosensitization in vivo.
      PubDate: 2013-09-30T09:26:26.694615-05:
      DOI: 10.1111/php.12168
       
  • On the Formation of Thymine Photodimers in Thymine Single Strands and Calf
           Thymus DNA
    • Authors: Lisbeth Munksgaard Baggesen; Søren Vrønning Hoffmann, Steen Brøndsted Nielsen
      Pages: 99 - 106
      Abstract: Solar light leads to thymine dimers that are mutagenic and primary cause of skin cancer. Here, we report absorption and synchrotron radiation circular dichroism (CD) spectra of Tn single strands with different number n of bases (n = 2–7, 10, 11) recorded after various 254 nm irradiation times. From a principal component analysis of the CD spectra, we extract fingerprint spectra of both the cyclobutane pyrimidine dimer (CPD) and the pyrimidine (6‐4) pyrimidone photoadduct (64PP). Extending the CD measurements to the vacuum ultraviolet region in combination with systematic examinations of size effects is a new approach to gain insight on the dimeric photoproducts. We find a simple linear correlation between n and average number of dimers formed after 1 h of irradiation. The probability for a thymine to engage in a dimer increases from 32% for n = 2 to 41% for n = 11, which implies limited effects of terminal thymines, i.e., the reaction does not occur preferentially at the extremities of the single strands as previously stated. It is even possible to form two dimers with only two bridging thymines. Finally, experiments conducted on calf thymus DNA provided a similar signature of the photodimer, but differences are also evident. Solar light causes mutagenic photodimers. Here we provide synchrotron radiation circular dichroism spectra of the photodimers, and we find that the yield of photodimers in thymine single strands increases linearly with the length. On average two are formed for strands with ten thymine bases.
      PubDate: 2013-11-28T05:30:15.095166-05:
      DOI: 10.1111/php.12183
       
  • Atrazine and Methyl Viologen Effects on Chlorophyll‐a Fluorescence
           Revisited—Implications in Photosystems Emission and Ecotoxicity
           Assessment
    • Authors: Analia Iriel; Johanna M. Novo, Gabriela B. Cordon, María G. Lagorio
      Pages: 107 - 112
      Abstract: In this work, we use the effect of herbicides that affect the photosynthetic chain at defined sites in the photosynthetic reaction steps to derive information about the fluorescence emission of photosystems. The interpretation of spectral data from treated and control plants, after correction for light reabsorption processes, allowed us to elucidate current controversies in the subject. Results were compatible with the fact that a nonnegligible Photosystem I contribution to chlorophyll fluorescence in plants at room temperature does exist. In another aspect, variable and nonvariable chlorophyll fluorescence were comparatively tested as bioindicators for detection of both herbicides in aquatic environment. Both methodologies were appropriate tools for this purpose. However, they showed better sensitivity for pollutants disconnecting Photosystem II–Photosystem I by blocking the electron transport between them as Atrazine. Specifically, changes in the (experimental and corrected by light reabsorption) red to far red fluorescence ratio, in the maximum photochemical quantum yield and in the quantum efficiency of Photosytem II for increasing concentrations of herbicides have been measured and compared. The most sensitive bioindicator for both herbicides was the quantum efficiency of Photosystem II. In this work we use the effect of herbicides at defined sites in the photosynthetic chain to derive information about the fluorescence emission of photosystems. Additionally, chlorophyll fluorescence was tested as a bioindicator for detection of both herbicides in aquatic environment.
      PubDate: 2013-08-20T05:24:10.345223-05:
      DOI: 10.1111/php.12142
       
  • Effect of Light Environment on Growth and Phenylpropanoids of Yarrow
           (Achillea collina cv. SPAK) Grown in the Alps
    • Authors: Annamaria Giorgi; Alessandra Manzo, Ilda Vagge, Sara Panseri
      Pages: 113 - 120
      Abstract: A 2‐year field study on the effect of different light environments, obtained by using cladding materials (polyethylene films and shade net) able to cut off specific regions of the photosynthetically active radiation and ultraviolet wavebands, on the growth and phenylpropanoids content of Achillea collina grown in the Alps was conducted. Overall the plant growth was strongly enhanced in the second growing season irrespective of radiation treatment. The light environment did not affect total biomass accumulation, but only carbon allocation to leaves or inflorescences. Indeed the phenylpropanoid levels in inflorescences appeared to be more sensitive to the light environment than leaves as the latter showed high constitutive amounts of these compounds. However, the use of polyethylene films improved to some extent the content of caffeic acid derivatives in leaves. Our results showed that yarrow production, in the alpine situation considered, is influenced by the growing season and the light environment, providing a basis to optimize its quality, depending on the concentration of bioactive compounds, by means of proper agronomic practices. A 2‐year field study on the effect of different light environments, obtained by using cladding materials able to cut off specific regions of the photosynthetically active radiation and ultraviolet wavebands, on the growth and phenylpropanoids content of Achillea collina grown in the Alps was conducted. Plant growth was strongly enhanced in the second growing season irrespective of radiation treatment. Phenylpropanoid levels in inflorescences appeared to be more sensitive to the light environment than leaves as the latter showed high constitutive amounts of these compounds. The use of polyethylene films improved to some extent the content of caffeic acid derivatives in leaves.
      PubDate: 2013-09-16T01:53:08.353999-05:
      DOI: 10.1111/php.12150
       
  • Synthesis of Zinc Chlorophyll Homo/Hetero‐Dyads and their Folded
           Conformers with Porphyrin, Chlorin, and Bacteriochlorin
           π‐Systems
    • Authors: Hitoshi Tamiaki; Kazuhiro Fukai, Hideki Shimazu, Sunao Shoji
      Pages: 121 - 128
      Abstract: Zinc complex of pyropheophorbide‐b, a derivative of chlorophyll‐b, was covalently dimerized through ethylene glycol diester. The synthetic homo‐dyad was axially ligated with two methanol molecules from the β‐face and both the diastereomerically coordinating methanol species were hydrogen bonded with the keto‐carbonyl groups of the neighboring chlorin in a complex. The resulting folded conformer in a solution was confirmed by visible, 1H NMR and IR spectra. All the synthetic zinc chlorin homo‐ and hetero‐dyads consisting of pyropheophorbides‐a, b and/or d took the above methanol‐locked and π–π stacked supramolecules in 1% (v/v) methanol and benzene to give redmost (Qy) electronic absorption band(s) at longer wavelengths than those of the corresponding monomeric chlorin composites. The other zinc chlorin and bacteriochlorin homo‐dyads completely formed similar folded conformers in the same solution, while zinc inverse chlorin and porphyrin homo‐dyads partially took such supramolecules. The J‐type aggregation to folded conformers and the redshift values of composite Qy bands were dependent on the electronic and steric factors of porphyrinoid moieties in dyads. Synthetic zinc chlorophyll dyads were intramolecularly folded with two methanol molecules to form their supramolecules by doubly coordinating and hydrogen‐bonding. The resulting π−π stacked J‐aggregates gave red‐shifted Qy bands in a solution.
      PubDate: 2013-10-21T00:52:22.951135-05:
      DOI: 10.1111/php.12173
       
  • Assessing the Applicability of Singlet Oxygen Photosensitizers in Leaf
           Studies
    • Authors: László Kovács; Ferhan Ayaydin, Tamás Kálai, Júlia Tandori, Péter B. Kós, Éva Hideg
      Pages: 129 - 136
      Abstract: Singlet oxygen (1O2) is of special interest in plant stress physiology. Studies focused on internal, chlorophyll‐mediated production are often complemented with the use of artificial 1O2 photosensitizers. Here, we report a comparative study on the effects of Rose Bengal (RB), Methylene Violet (MVI), Neutral Red (NR) and Indigo Carmine (IC). These were infiltrated into tobacco leaves at concentrations generating the same fluxes of 1O2 in solution. Following green light‐induced 1O2 production from these dyes, leaf photosynthesis was characterized by Photosystem (PS) II and PSI electron transport and oxidative damage was monitored as degradation of D1, a PSII core protein. Cellular localizations were identified on the basis of the dyes’ fluorescence using confocal laser scanning microscopy. We found that RB and NR were both localized in chloroplasts but the latter had very little effect, probably due to its pH‐dependent photosensitizing. Both RB and intracellular, nonplastid MVI decreased PSII electron transport, but the effect of RB was stronger than that of MVI and only RB was capable of damaging the D1 protein. Intercellularly localized IC had no significant effect. Our results also suggest caution when using RB as photosensitizer because it affects PSII electron transport. Confocal microscopy imaging of tobacco leaf cells loaded with the photosensitizer Rose Bengal. Composite image shows Rose Bengal fluorescence as green and chlorophyll fluorescence as red.
      PubDate: 2013-09-04T08:34:04.433299-05:
      DOI: 10.1111/php.12148
       
  • A Novel Catalytic Function of Synthetic IgG‐Binding Domain (Z
           
    • Authors: Satoshi Inouye; Yuiko Sahara‐Miura
      Pages: 137 - 144
      Abstract: The synthetic IgG‐binding domain (Z domain) of staphylococcal protein A catalyzes the oxidation of coelenterazine to emit light like a coelenterazine‐utilizing luciferase. The Z domain derivatives (ZZ‐gCys, Z‐gCys and Z‐domain) were purified and the luminescence properties were characterized by comparing with coelenterazine‐utilizing luciferases, including Renilla luciferase, Gaussia luciferase and the catalytic 19 kDa protein of Oplophorus luciferase. Three Z domain derivatives showed luminescence activity with coelenterazine and the order of the initial maximum intensity of luminescence was ZZ‐gCys (100%) > Z‐gCys (36.8%) > Z‐domain (1.1%) > bovine serum albumin (BSA; 0.9%) > staphylococcal protein A (0.1%) and the background value of coelenterazine (0.1%) in our conditions. The luminescence properties of ZZ‐gCys showed the similarity to that of Gaussia luciferase, including the luminescence pattern, the emission spectrum, the stimulation by halogen ions and nonionic detergents and the substrate specificity for coelenterazine analogues. In contrast, the luminescence properties of Z‐gCys were close to the catalytic 19 kDa protein of Oplophorus luciferase. The catalytic region of the Z domain for the luminescence reaction might be different from the IgG‐binding region of the Z domain. The synthetic IgG‐binding domain (Z domain) of staphylococcal protein A catalyzes the oxidation of coelenterazine to emit light like a coelenterazine‐utilizing luciferase. The catalytic properties of the Z domain and the dimmer of Z domain are close to the Oplophorus luciferase and Gaussia luciferase, respectively.
      PubDate: 2013-11-27T05:45:23.763476-05:
      DOI: 10.1111/php.12192
       
  • Cyclobutane Pyrimidine Dimer Density as a Predictive Biomarker of the
           Biological Effects of Ultraviolet Radiation in Normal Human Fibroblast
    • Authors: Christopher D. Sproul; David L. Mitchell, Shangbang Rao, Joseph G. Ibrahim, William K. Kaufmann, Marila Cordeiro‐Stone
      Pages: 145 - 154
      Abstract: This study compared biological responses of normal human fibroblasts (NHF1) to three sources of ultraviolet radiation (UVR), emitting UVC wavelengths, UVB wavelengths, or a combination of UVA and UVB (solar simulator; emission spectrum, 94.3% UVA and 5.7% UVB). The endpoints measured were cytotoxicity, intra‐S checkpoint activation, inhibition of DNA replication and mutagenicity. Results show that the magnitude of each response to the indicated radiation sources was best predicted by the density of DNA cyclobutane pyrimidine dimers (CPD). The density of 6‐4 pyrimidine–pyrimidone photoproducts was highest in DNA from UVC‐irradiated cells (14% of CPD) as compared to those exposed to UVB (11%) or UVA–UVB (7%). The solar simulator source, under the experimental conditions described here, did not induce the formation of 8‐oxo‐7,8‐dihydroguanine in NHF1 above background levels. Taken together, these results suggest that CPD play a dominant role in DNA damage responses and highlight the importance of using endogenous biomarkers to compare and report biological effects induced by different sources of UVR. Exposure to UV, including the more energetic wavelengths present in sunlight (UVB), leads to the formation of DNA photoproducts. Among these, the cyclobutane pyrimidine dimers (CPD) are the most abundant. CPD density in DNA of diploid human fibroblasts irradiated with three different UV irradiation sources correlated best with the measured biological outcomes.
      PubDate: 2013-11-28T05:30:19.703502-05:
      DOI: 10.1111/php.12194
       
  • Regulation of MSK1‐Mediated NF‐κB Activation Upon UVB
           Irradiation
    • Authors: Oliver L. Carpenter; Shiyong Wu
      Pages: 155 - 161
      Abstract: Nuclear Factor Kappa‐B (NF‐κB) is a transcription factor that controls expression of genes involved in the immune and inflammatory responses as well as being a key component in the onset of cancers. In this study, we provided evidence that mitogen‐ and stress‐activated protein kinase (MSK1) is responsible for a noncanonical late‐phase activation of NF‐κB upon UVB irradiation. Our data demonstrated that following UVB irradiation, MSK1 is activated via phosphorylation at the 24 h time point coinciding with translocation of NF‐κB into the nucleus. Investigations into the signaling pathways upstream of MSK1 through the use of specific inhibitors for mitogen‐activated protein kinase and p38 revealed that both kinases are required for full phosphorylation during the late phase (24 h), while p38 is paramount for phosphorylation during the early phase (6 h). Electromobility shift assays (EMSA) showed that inhibition of MSK1 resulted in a marked reduction in NF‐κB binding affinity without altering the nuclear translocation of NF‐κB. Supershift EMSA implicate that the p65, but not p50, isoform of NF‐κB is involved in late‐phase activation in response to UVB irradiation. Together, the results of these studies shed light onto a novel pathway of MSK1‐mediated late‐phase activation of NF‐κB in response to UVB irradiation. Proposed model of MSK‐1mediated NF‐κB activation following UVB irradiation: UVB irradiation stimulates the activation of MSK1 via phosphorylation from ERK and p38. During the early‐phase response, activation of MSK1 is heavily dependent on the function of p38, as opposed to the late‐phase in which p38 and ERK work in a concerted effort to phosphorylate MSK1. Although MSK1 is highly phosphorylated during the early‐phase, it is not until UVB has stimulated the translocation of NF‐κB into the nucleus of the cell during the late‐phase that MSK1 is able to transactivate NF‐κB into a fully active form.
      PubDate: 2013-09-30T09:26:25.025991-05:
      DOI: 10.1111/php.12163
       
  • Photohemolysis Sensitized by the Furocoumarin Derivative Alloimperatorin
           and its Hydroperoxide Photooxidation Product
    • Authors: Alla Kyagova; Alexander Potapenko, Marianne Möller, Helga Stopper, Waldemar Adam
      Pages: 162 - 170
      Abstract: The dark and photosensitized effects of alloimperatorin methyl ether 1 (hereafter simply alloimperatorin) and its photooxygenation product alloimperatorin hydroperoxide 2 were investigated on human erythrocytes. The results reveal that the furocoumarin 1 photosensitizes efficiently the hemolysis of erythrocytes. The rate of photohemolysis increases on raising the temperature of the postirradiated incubation from 4°C to 37°C. Thermal activation of the photohemolysis and inhibition by 2,6‐di‐tert‐butyl‐p‐cresol (BHT) suggest that the furocoumarin 1 photosensitizes lipid peroxidation, increasing permeability in the erythrocyte membrane. The hydroperoxide 2 induces dark and photosensitized hemolysis more efficiently than the furocoumarin 1. The rate of hemolysis induced by 2 increases with the incubation temperature and decreases in the presence of tert‐butanol and BHT. The hydroperoxide 2 photosensitizes the formation of lipid peroxidation products as shown by the reaction with thiobarbituric acid. This process is diminished by BHT. Our data imply that the photohemolysis sensitized by the furocoumarin 1 is caused by the in situ‐formed photooxygenation product 2. Such hydroperoxides are potent hemolytic agents in the dark and especially on photosensitization. The alloimperatorin 1 photosensitizes efficiently the hemolysis of erythrocytes (panel A). The rate of photohemolysis increases on raising the temperature of the post‐irradiated incubation from 4°C to 37°C. Alloimperatorin 1 is autophotooxidized forming its hydroperoxide 2. The hydroperoxide 2 induces dark and photosensitized hemolysis more efficiently (panel B) than 1, and photosensitizes the formation of lipid‐peroxidation products in erythrocytes. These processes are inhibited by tert‐butanol and 2,6‐di‐tert‐butyl‐p‐cresol. Our data imply that the photohemolysis sensitized by the alloimperatorin 1 is caused by the in‐situ‐formed hydroperoxide 2.
      PubDate: 2013-11-25T05:22:38.349579-05:
      DOI: 10.1111/php.12184
       
  • Complexes of Chlorin e6 with Pluronics and Polyvinylpyrrolidone: Structure
           and Photodynamic Activity in Cell Culture
    • Authors: Timur M. Zhiyentayev; Umed T. Boltaev, Anna B. Solov'eva, Nadezhda A. Aksenova, Nickolay N. Glagolev, Alexander V. Chernjak, Nickolay S. Melik‐Nubarov
      Pages: 171 - 182
      Abstract: Polymeric carriers are extensively used in photodynamic therapy (PDT) for increase of efficacy of photosensitizers. Here, we report the influence of nine Pluronic copolymers on phototoxicity of chlorin e6 (Ce6), in particular 5‐ to 7‐fold rise in the phototoxicity caused by hydrophilic Pluronics F127, F108, F68 and F87 and practically no influence on Ce6 of more hydrophobic polymers. The revealed value of 0.2 mg mL−1 of Pluronic F127 concentration sufficient for half‐of‐maximal increase of Ce6 photodynamic activity proved to be close to 0.16 mg mL−1 inherent in well‐documented carrier poly(N‐vinylpyrrolidone) (PVP). The dissociation constants of Ce6 complexes with Pluronic F127 and PVP that were estimated from UV spectra were 0.252 and 0.036 mg mL−1, respectively, indicating higher stability of Ce6 complex with PVP. According to the results of 1H‐NMR studies of Ce6 complexes, the porphyrin interacts not only with hydrophobic regions but also with hydrophilic sides of both polymers. Non‐covalent binding of Chlorin e6 to hydrophilic polymers results in 5–7‐fold enhancement of its phototoxicity in vitro.
      PubDate: 2013-11-28T05:30:11.693953-05:
      DOI: 10.1111/php.12181
       
  • A Comparative Study of the Photosensitizer Penetration into Artificial
           Caries Lesions in Dentin Measured by the Confocal Raman Microscopy
    • Authors: Mary Anne S. Melo; Juliana P.M.L. Rolim, Iriana C.J. Zanin, José J.A. Silva, Alexandre R. Paschoal, Alejandro P. Ayala, Lidiany K.A. Rodrigues
      Pages: 183 - 188
      Abstract: This study utilized the confocal Raman microspectroscopy (CRM) technique for the first time to investigate the degree of the penetration of toluidine blue‐orto (TBO) in artificial caries lesions produced by two distinct caries‐inducing models. The dentin specimens (n = 10) were divided into three groups: control, in vitro and in situ. Thereafter, the lesion depth and the demineralization level were evaluated by cross‐sectional microhardness (CSMH). CRM mapping across the dentin surface was assessed after the dye application. The CSMH and CRM data were analyzed by t‐test and ANOVA, respectively (P 
      PubDate: 2013-11-25T05:22:32.29055-05:0
      DOI: 10.1111/php.12186
       
  • Photodynamic and Nail Penetration Enhancing Effects of Novel
           Multifunctional Photosensitizers Designed for The Treatment of
           Onychomycosis
    • Authors: Threes Smijs; Zoë Dame, Ellen Haas, Jan‐Bonne Aans, Stan Pavel, Henricus Sterenborg
      Pages: 189 - 200
      Abstract: Novel multifunctional photosensitizers (MFPSs), 5,10,15‐tris(4‐N‐methylpyridinium)‐20‐(4‐phenylthio)‐[21H,23H]‐porphine trichloride (PORTH) and 5,10,15‐tris(4‐N‐methylpyridinium)‐20‐(4‐(butyramido‐methylcysteinyl)‐hydroxyphenyl)‐[21H,23H]‐porphine trichloride (PORTHE), derived from 5,10,15‐Tris(4‐methylpyridinium)‐20‐phenyl‐[21H,23H]‐porphine trichloride (Sylsens B) and designed for treatment of onychomycosis were characterized and their functionality evaluated. MFPSs should function as nail penetration enhancer and as photosensitizer for photodynamic treatment (PDT) of onychomycosis. Spectrophotometry was used to characterize MFPSs with and without 532 nm continuous‐wave 5 mW cm−2 laser light (± argon/mannitol/NaN3). Nail penetration enhancement was screened (pH 5, pH 8) using water uptake in nails and fluorescence microscopy. PDT efficacy was tested (pH 5, ± argon/mannitol/NaN3) in vitro with Trichophyton mentagrophytus microconida (532 nm, 5 mW cm−2). A light‐dependent absorbance decrease and fluorescence increase were found, PORTH being less photostable. Argon and mannitol increased PORTH and PORTHE photostability; NaN3 had no effect. PDT (0.6 J cm−2, 2 μm) showed 4.6 log kill for PORTH, 4.4 for Sylsens B and 3.2 for PORTHE (4.1 for 10 μm). Argon increased PORTHE, but decreased PORTH PDT efficacy; NaN3 increased PDT effect of both MFPSs whereas mannitol increased PDT effect of PORTHE only. Similar penetration enhancement effects were observed for PORTH (pH 5 and 8) and PORTHE (pH 8). PORTHE is more photostable, effective under low oxygen conditions and thus realistic candidate for onychomycosis PDT. Double functionality of a multifunctional photosensitizer when applied the dermatophyte Trichophyton mentagrophytus in the presence of nail material: a nail penetration enhancement function and a function as photosensitizer for green light photodynamic treatment of onychomycosis. The possibility of these compounds to weaken the nail plate is based on their keratolytic capacity, viz. the possibility of SH‐containing compounds to chemically reduce the covalent disulphide bonds as present in keratin protein fibers in human nail plates. The cationic part of the novel molecules should be responsible for the desired selective (pH 5) PDT effect when binding (•) to fungal hyphae.
      PubDate: 2013-11-25T02:30:18.529973-05:
      DOI: 10.1111/php.12196
       
  • Effects of Laser Irradiation on Pulp Cells Exposed to Bleaching Agents
    • Authors: Adriano F. Lima; Fernanda G. Basso, Ana P. D. Ribeiro, Vanderlei S. Bagnato, Josimeri Hebling, Giselle M. Marchi, Carlos A. Souza Costa
      Pages: 201 - 206
      Abstract: The aim of this study was to evaluate the effect of low‐level laser therapy (LLLT) on odontoblast‐like cells exposed to a bleaching agent. Mouse dental papilla cell‐23 cells were seeded in wells of 24‐well plates. Eight groups were established according to the exposure to the bleaching agent and LLLT (0, 4, 10 and 15 J cm−2). Enamel–dentin disks were adapted to artificial pulp chambers, which were individually placed in wells containing Dulbecco's modified Eagle's medium (DMEM). A bleaching agent (35% hydrogen peroxide [BA35%HP]) was applied on enamel (15 min) to obtain the extracts (DMEM + BA35%HP components diffused through enamel/dentin disks). The extracts were applied (1 h) to the cells, and then subjected to LLLT. Cell viability (Methyl tetrazolium assay), alkaline phosphatase (ALP) activity, as well as gene expression of ALP, fibronectin (FN) and type I collagen, were evaluated. The bleaching procedures reduced the cell viability, ALP activity and gene expression of dentin proteins. Laser irradiation did not modulate the cell response; except for FN, as LLLT decreased the gene expression of this protein by the cells exposed to the BA35%HP. It can be concluded that BA35%HP decreased the activities of odontoblasts that were not recovered by the irradiation of the damaged cells with low‐level laser parameters tested. The aim of the present study was to evaluate the effect of low‐level laser therapy (LLLT) on odontoblast‐like cells exposed to a bleaching agent. Eight groups were established according to the exposure to the bleaching agent (35% hydrogen peroxide) and LLLT (0, 4, 10, and 15 J cm−2). The bleaching procedures reduced the cell viability, ALP activity, and gene expression of dentin proteins. Laser irradiation did not modulate the cell response; except for FN, since LLLT decreased the gene expression of this protein by the cells exposed to the 35% hydrogen peroxide.
      PubDate: 2013-09-13T23:52:47.763028-05:
      DOI: 10.1111/php.12155
       
  • Protection from UVB Toxicity in Human Keratinocytes by Thailand Native
           Herbs Extracts
    • Authors: Visa Thongrakard; Nijsiri Ruangrungsi, Maneerat Ekkapongpisit, Ciro Isidoro, Tewin Tencomnao
      Pages: 214 - 224
      Abstract: Thai traditional medicine employs a wide range of indigenous herbs in the forms of tincture or tea for the cure of skin and systemic inflammatory diseases. The protection by Thai plants extracts against UVB DNA damage and cytotoxicity was investigated in human keratinocytes. Petroleum ether, dichloromethane and ethanol extracts were prepared from 15 Thai herb species, and the total phenolic and flavonoid contents, the antioxidant and UV‐absorbing properties were assessed by standard procedures. Cytoprotective effects were evaluated on the basis of cell survival, caspase‐3 activity and pyrimidine dimers determination. High total phenolic and flavonoid contents were found in the ethanol and dichloromethane fractions. Dichloromethane extract of turmeric was shown to possess the highest antioxidant activity. The maximum UV absorptions were found in the ethanol extract of turmeric and in the dichloromethane extract of ginger. These extracts stimulated the synthesis of Thioredoxin 1, an antioxidant protein, and could protect human HaCaT keratinocytes from UV‐induced DNA damage and cytotoxicity. The present data support the utilization of turmeric and ginger extracts in anti‐UV cosmetic pharmaceuticals. The protection by Thai plants extracts against UVB DNA damage and cytotoxicity was investigated in human keratinocytes. Ethanol extract of turmeric and dichloromethane extract of ginger were shown to possess the maximum UV absorptions (a). These extracts stimulated the synthesis of Thioredoxin 1, an antioxidant protein (b), and could protect human HaCaT keratinocytes exposed to UVB from DNA damage (d) and caspase‐3‐mediated apoptosis (c). The present data support the utilization of turmeric and ginger extracts in anti‐UV cosmetic pharmaceuticals.
      PubDate: 2013-09-03T00:16:19.628044-05:
      DOI: 10.1111/php.12153
       
  • Spectral and Spatial UV Sky Radiance Measurements at a Seaside Resort
           Under Clear Sky and Slightly Overcast Conditions
    • Authors: Henner Sandmann; Carsten Stick
      Pages: 225 - 232
      Abstract: Spatial measurements of the diffusely scattered sky radiance at a seaside resort under clear sky and slightly overcast conditions have been used to calculate the sky radiance distribution across the upper hemisphere. The measurements were done in the summer season when solar UV radiation is highest. The selected wavelengths were 307, 350 and 550 nm representing the UVB, UVA and VIS band. Absolute values of radiance differ considerably between the wavelengths. Normalizing the measured values by use of direct solar radiance made the spatial distributions of unequal sky radiance comparable. The results convey a spatial impression of the different distributions of the radiance at the three wavelengths. Relative scattered radiance intensity is one order of magnitude greater in UVB than in VIS, whereas in UVA lies roughly in between. Under slightly overcast conditions scattered radiance is increased at all three wavelengths by about one order of magnitude. These measurements taken at the seaside underline the importance of diffuse scattered radiance. The effect of shading parts of the sky can be estimated from the distribution of sky radiance. This knowledge might be useful for sun seekers and in the treatment of people staying at the seaside for therapeutic purposes. Spatial measurements of the diffusely scattered sky radiance at a seaside resort under clear sky and slightly overcast conditions have been used to calculate the sky radiance distribution across the hemisphere. The measurements were done shortly after the solstice at 307 nm, 350 nm and 550 nm representing UVB, UVA and VIS. Normalizing the measured values by use of direct solar radiation made the spatial distributions of sky radiance comparable. The results convey a spatial impression of the distribution of the radiance. The effect of shading parts of the sky can be estimated from the radiance distribution.
      PubDate: 2013-11-01T06:57:28.410833-05:
      DOI: 10.1111/php.12180
       
  • Smartphone‐Based Android app for Determining UVA Aerosol Optical
           Depth and Direct Solar Irradiances
    • Authors: Damien P. Igoe; Alfio Parisi, Brad Carter
      Pages: 233 - 237
      Abstract: This research describes the development and evaluation of the accuracy and precision of an Android app specifically designed, written and installed on a smartphone for detecting and quantifying incident solar UVA radiation and subsequently, aerosol optical depth at 340 and 380 nm. Earlier studies demonstrated that a smartphone image sensor can detect UVA radiation and the responsivity can be calibrated to measured direct solar irradiance. This current research provides the data collection, calibration, processing, calculations and display all on a smartphone. A very strong coefficient of determination of 0.98 was achieved when the digital response was recalibrated and compared to the Microtops sun photometer direct UVA irradiance observations. The mean percentage discrepancy for derived direct solar irradiance was only 4% and 6% for observations at 380 and 340 nm, respectively, lessening with decreasing solar zenith angle. An 8% mean percent difference discrepancy was observed when comparing aerosol optical depth, also decreasing as solar zenith angle decreases. The results indicate that a specifically designed Android app linking and using a smartphone image sensor, calendar and clock, with additional external narrow bandpass and neutral density filters can be used as a field sensor to evaluate both direct solar UVA irradiance and low aerosol optical depths for areas with low aerosol loads. The comparison of aerosol optical depth (AOD) at 380 nm derived from an Android app specifically written and calibrated, installed on a LG Optimus L3 smartphone compared to the subsequent readings from a Microtops sun photometer. This close relationship was achieved by calibrating, testing and validating an Android app on clear days at two locations in south east Queensland, Australia.
      PubDate: 2013-11-25T05:22:34.80424-05:0
      DOI: 10.1111/php.12185
       
  • Novel Collimated Beam Setup to Study the Kinetics of VUV‐Induced
           Reactions
    • Authors: Clara Duca; Gustavo Imoberdorf, Madjid Mohseni
      Pages: 238 - 240
      Abstract: Vacuum UV (VUV) process is an incipient advanced oxidation process, which can be used for water treatment. This process relies on the formation of hydroxyl radicals through the VUV‐induced photolysis of water. In particular, the use of ozone‐generating mercury vapor lamps, which emit 10% of the radiation at 185 nm and 90% at 254 nm, is showing very promising results for the degradation of micropollutants. The kinetics of VUV process has been studied in batch‐ and flow‐through reactors, but the effect of 254 and 185 nm photons cannot be isolated, mass transfer resistances can take place and the interpretation of the results is complex. In this technical note, a new VUV collimated beam to conduct kinetic tests is presented, which offers several advantages: (1) it allows the irradiation of samples with 185, 254 nm photons, or both, (2) the concentration of reagents is uniform in the reaction volume and (3) it allows to change the fluence rate by changing the distance between the lamp and the photoreactor. Details of the geometry are presented, as well as an analysis of the collimation and uniformity of the radiation of the new VUV‐collimated beam setup. Vacuum UV (VUV) process is an incipient advanced oxidation process (AOP), which can be used for water treatment. HO radicals are formed through the VUV‐induced (185 nm) photolysis of water. Ozone generating mercury vapor lamps, which emit 10% of the radiation at 185 nm and 90% at 254 nm, are usually used for the degradation of micropollutants. Conventional UV‐collimated beam setups cannot be used to study VUV processes as oxygen in air absorbs 185 nm photons. In this technical note, a new VUV‐collimated beam, which allows the irradiation of samples with 185, 254 nm radiation, or both, is presented.
      PubDate: 2013-09-20T00:48:15.366721-05:
      DOI: 10.1111/php.12157
       
  • UVA and UVB‐Induced 8‐Methoxypsoralen Photoadducts and a Novel
           Method for their Detection by Surface‐Enhanced Laser Desorption
           Ionization Time‐of‐Flight Mass Spectrometry (SELDI‐TOF
           MS)
    • Authors: Alexandru D. Buhimschi; Francis P. Gasparro
      Pages: 241 - 246
      Abstract: UVA‐activated psoralens are used to treat hyperproliferative skin conditions due to their ability to form DNA photoadducts, which impair cellular processes and may lead to cell death. Although UVA (320–400 nm) is more commonly used clinically, studies have shown that UVB (280–320 nm) activation of psoralen can also be effective. However, there has been no characterization of UVB‐induced adduct formation in DNA alone. As psoralen derivatives have a greater extinction coefficient in the UVB region (11 800 cm−1 M−1 at 300 nm) compared with the UVA region (2016 cm−1 M−1 at 365 nm), a greater extent of adduct formation is expected. SELDI‐TOF, a proteomic technique that combines chromatography with mass spectrometry, was used to detect photoadduct formation in an alternating A–T oligonucleotide. 8‐Methoxypsoralen (8‐MOP) and DNA solutions were irradiated with either UVA or UVB. An adduct peak was obtained with SELDI‐TOF. For UVB‐activated 8‐MOP, the extent of adducts was three times greater than for UVA. HPLC ESI‐MS analysis showed that UVB irradiation yielded high levels of 3,4‐monoadducts (78% of total adducts). UVA was more effective than UVB at conversion of 4′,5′‐monoadducts to crosslinks (17% vs 4%, respectively). This report presents a method for comparing DNA binding efficiencies of interstrand crosslink inducing agents. Upon irradiation with ultraviolet light, a DNA intercalated 8‐Methoxypsoralen (8‐MOP) molecule will bind to an adjacent thymine, leading to monoadduct formation. Also shown is a SELDI‐TOF MS tracing of an 8‐MOP and DNA solution irradiated with 17.7 J cm−2 of UVB. Using an alternating 10 bp adenine and thymine oligonucleotide (3025 m/z), we observed the dose dependent formation of a peak at 3241 m/z, which corresponds to the combined mass of our oligonucleotide and an 8‐MOP molecule. This novel protocol provided a rapid modality for assessing the overall binding efficiencies and stoichiometries of psoralen derivatives upon irradiation in the presence of DNA.
      PubDate: 2013-10-17T02:37:45.499455-05:
      DOI: 10.1111/php.12171
       
  • Chemical Analysis of the Luminous Slime Secreted by the Marine Worm
           Chaetopterus (Annelida, Polychaeta)
    • Authors: Bruce R. Branchini; Curran E. Behney, Tara L. Southworth, Renu Rawat, Dimitri D. Deheyn
      Pages: 247 - 251
      Abstract: The marine annelid Chaetopterus variopedatus produces bioluminescence by an unknown and potentially novel mechanism. We have advanced the study of this fascinating phenomenon, which has not been investigated for nearly 60 years after initial studies were first reported for this species. Here, we show that the luminous slime produced by the worm exhibits blue fluorescence that matches the bioluminescence emission. This result suggests that the oxyluciferin emitter is present. However, while the blue fluorescence decays over time green fluorescence is increasingly revealed that is likely associated with products of the luminescence reaction. LC/MS and fluorescence analysis of harvested luminescent material revealed riboflavin as the major green fluorescent component. Riboflavin is usually associated with the mechanism of light production in bacteria, yet luminous bacteria were not found in the worm mucus, and accordingly were not reported to be directly responsible for the light emission, which is under nervous control in the worm. We therefore propose a hypothesis in which riboflavin or a structurally related derivative serves as the emitter in the worm's light producing reaction. The marine worm Chaetopterus variopedatus produces bioluminescence by an unknown mechanism. We show that the luminous slime produced by the worm exhibits blue fluorescence that matches the bioluminescence emission suggesting that the oxyluciferin emitter is present. As the blue fluorescence decays over time green fluorescence is increasingly revealed. We determined that riboflavin is the major green fluorescent component. It is likely that riboflavin accounts for the green fluorescence observed throughout the worm and we speculate that riboflavin or a structurally related derivative serves as the emitter in the worm's light producing reaction.
      PubDate: 2013-10-17T07:12:26.271028-05:
      DOI: 10.1111/php.12169
       
  • Scrambled Self‐Assembly of Bacteriochlorophylls c and e in Aqueous
           Triton X‐100 Micelles
    • Abstract: Bacteriochlorophyll (BChl) e was co‐assembled with BChl c in Triton X‐100 micelles in aqueous solutions. The Qy absorption bands of the co‐aggregates were positioned between those of aggregates consisting solely of BChl c or e. The electronic absorption spectra of the co‐aggregates could not be reproduced by linear combinations of the spectra of the aggregates consisting solely of each pigment, but they were in line with the simulated spectra for the self‐aggregates in which both BChls were randomly distributed. These suggest that BChls c and e are not spatially separated; they are homogenously distributed over the self‐aggregates to give electronic spectra that are different from those of the aggregate consisting solely of each pigment. Deaggregation of the scrambled self‐aggregates by excess Triton X‐100 did not produce any spectral components assigned to an aggregate consisting solely of either BChl c or e. Acid‐induced decomposition of the scrambled aggregates showed different kinetics from those of the aggregates consisting solely of each pigment. These also support the homogeneous distribution of BChls c and e in the scrambled self‐aggregates. These results will be useful to investigate the major light‐harvesting antenna systems of green photosynthetic bacteria that contain two kinds of chlorosomal BChls. This article is protected by copyright. All rights reserved.
       
  • One Component Thioxanthone Acetic Acid Derivative Photoinitiator for Free
           Radical Polymerization
    • Abstract: Acetic acid based thioxanthone (TXCH2COOH) was synthesized and characterized and used as a photoinitiator for free radical photopolymerization of methyl methacrylate (MMA) in the absence and presence of a tertiary amine (MDEA) in different solvents. Different absorption properties were observed depending on the solvent. Fluorescence and phosphorescence experiments were also carried out successfully. The fluorescence quantum yield was found to be 0.09 and the phosphorescence lifetime was calculated as 138 ms at 77K. The photoinitiator undergoes efficient intersystem crossing into the triplet state and the lowest triplet state posseses π‐π* configuration. Laser flash photolysis experiments show that transient absorption of TXCH2COOH is similar to the parent thioxanthone and the triplet lifetime was calculated as 2.3 μs at 630 nm. This article is protected by copyright. All rights reserved.
       
 
 
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