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Photochemistry and Photobiology

Raymond E Borg, Maryam Hatamimoslehabadi, Stephanie Bellinger, Jeffrey La, Farha Mithila, Chandra Yelleswarapu, Jonathan Rochford
The synthesis, photophysical and photoacoustic characterization for a series of nine π-extended quadrupolar curcumin dyes is presented. A systematic evaluation of the π-bridging unit including the p-phenyl, naphth-4-yl, thien-2-yl and hybrid 4-naphthathien-2-yl groups is presented. Furthermore, evaluation of the strongly donating donor-π-acceptor-π-donor quadrupolar dimethylamino terminated derivatives is also included. Select dyes exhibit excited state absorption at increased laser fluence which translates to production of a nonlinear enhanced photoacoustic response...
July 10, 2018: Photochemistry and Photobiology
José Rodríguez-Aguilar, Matías Vidal, Camila Pastenes, Carolina Aliaga, Marcos Caroli Rezende, Moisés Domínguez
Seven new 2,4,6-triarylpyrimidines were synthesized and their solvatofluorochromism investigated in 12 solvents and in an aqueous micellar solution of reduced Triton X-100. A multiparametric analysis of their emission band showed that the solvent dipolarity and basicity were mainly responsible for their solvatofluorochromism, which arose from an internal charge-transfer from a donor fragment to the pyrimidine acceptor, confirmed by theoretical calculations. In the micellar system, quenching of their fluorescence by addition of derivatives of 2,2,6,6-tetramethylpiperidinoxyl (TEMPO) radical was investigated, and the results were consistent with the spectral changes brought about by the micro-heterogeneous system...
July 8, 2018: Photochemistry and Photobiology
Yair E Litman, Hernán B Rodríguez, Silvia E Braslavsky, Enrique San Román
The photophysical behavior of two xanthene dyes, Eosin Y and Phloxine B, included in microcrystalline cellulose particles is studied in a wide concentration range, with emphasis on the effect of dye concentration on fluorescence and triplet quantum yields. Absolute fluorescence quantum yields in the solid-state were determined by means of diffuse reflectance and steady-state fluorescence measurements, whereas absolute triplet quantum yields were obtained by laser-induced optoacoustic spectroscopy and their dependence on dye concentration was confirmed by diffuse reflectance laser flash photolysis and time-resolved phosphorescence measurements...
July 7, 2018: Photochemistry and Photobiology
Marely E Tejeda-Ferrari, Chelsea L Brown, Gabriela C C C Coutinho, Ghabriel A Gomes de Sá, Julio L Palma, Manuel J Llansola-Portoles, Gerdenis Kodis, Vladimiro Mujica, Junming Ho, Devens Gust, Thomas A Moore, Ana L Moore
Three Pd(II) phthalocyanine-carotenoid dyads featuring chromophores linked by amide bonds were prepared in order to investigate the rate of triplet-triplet (T-T) energy transfer from the tetrapyrrole to the covalently attached carotenoid as a function of the number of conjugated double bonds in the carotenoid. Carotenoids having 9, 10 and 11 conjugated double bonds were studied. Transient absorption measurements show that intersystem crossing in the Pd(II) phthalocyanine takes place in 10 ps in each case and that T-T energy transfer occurs in 126 ps, 81 ps and 132 ps in the dyads bearing 9, 10 and 11 double bond carotenoids, respectively...
July 7, 2018: Photochemistry and Photobiology
Weichao Sun, Yi Liao, Qian Yi, Shiyong Wu, Liling Tang, Lingying Tong
Cold-inducible RNA binding protein (CIRP) is a stress-inducible protein, which could be activated by various cellular stresses, such as hypothermia, hypoxia and UV irradiation. Our previous study indicated that UVB (3 mJ/cm2 ) induces CIRP expression, which promotes keratinocytes growth, survival and eventually transformation via activation of STAT3-Bag-1/S signaling cascade. However, the mechanism(s) of CIRP in regulating p-STAT3 activation and Bag-1/S expression have not been fully elucidated. In this study, we demonstrate that repeated exposure of UVB (3 mJ/cm2 ) or overexpression of CIRP could lead to an elevation of the phosphorylation of Janus kinase (JAK) family proteins (JAK2 and JAK3) in HaCaT cells...
July 7, 2018: Photochemistry and Photobiology
Naitielle Pantano, Brady Hunt, Richard A Schwarz, Sonia Parra, Katelin Cherry, Júlio César Possati-Resende, Adhemar Longatto-Filho, José Humberto Tavares Guerreiro Fregnani, Philip E Castle, Kathleen Schmeler, Rebecca Richards-Kortum
Proflavine is an acridine dye used with high-resolution microendoscopy for in vivo diagnostic evaluation of cervical epithelial cells. However, there are concerns that even short-term exposure of cervical tissue to dilute proflavine may increase cervical cancer risk. We performed a retrospective analysis of women referred for colposcopy to Barretos Cancer Hospital comparing the risk of cervical disease progression in those whose cervical tissue was (n=232) or was not exposed (n=160) to proflavine. Patients in both groups underwent treatment and follow-up based on histopathologic results and per the local standards of care...
July 7, 2018: Photochemistry and Photobiology
Ali İmran Vaizoğullar
Visible light driven novel and highly efficient AgBr/ZnO photocatalysts were synthesized by a facile precipitation and dehydration methods. The synthesized samples were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence (PL) techniques. Within various combinations of AgBr and ZnO components in the composites, 1AgBr/ZnO showed higher photocatalytic activity against 3-chlorophenol (3-CP)...
July 6, 2018: Photochemistry and Photobiology
Gustavo Thalmer M Silva, Suma S Thomas, Cassio Pacheco Silva, Jan C Schlothauer, Mauricio S Baptista, Adilson A Freitas, Cornelia Bohne, Frank H Quina
During the maturation of red wines, the anthocyanins of grapes are transformed into pyranoanthocyanins, which possess a pyranoflavylium cation as their basic chromophore. Photophysical properties of the singlet and triplet excited states of a series of synthetic pyranoflavylium cations were determined at room temperature in acetonitrile solution acidified with 0.10 mol dm-3 trifluoroacetic acid (TFA, to inhibit competitive excited state proton transfer) and at 77 K in a rigid TFA-acidified isopropanol glass...
July 6, 2018: Photochemistry and Photobiology
María Belén Rivas Aiello, Daniel Castrogiovanni, Julieta Parisi, Julio C Azcárate, Fernando S García Einschlag, Thomas Gensch, Gabriela N Bosio, Daniel O Mártire
Riboflavin (Rf) is an endogenous photosensitizer, which can participate in Type I and Type II processes. We have recently shown that the yield of the triplet excited states of Rf is enhanced in the presence of pectin-coated silver nanoparticles (Pec@AgNP) due to formation of a complex between Rf and Pec@AgNP (Rf-Pec@AgNP). Consequently, under aerobic conditions the amounts of singlet molecular oxygen and superoxide radical anion generated are also larger in the presence of the nanoparticles. This result made us suspect that the nanoparticles could have a beneficial effect in Rf-based PDT...
July 6, 2018: Photochemistry and Photobiology
Brennan Ashwood, Marvin Pollum, Carlos E Crespo-Hernández
Sulfur-substituted nucleobases (a.k.a., thiobases) are among the world's leading prescriptions for chemotherapy and immunosuppression. Long-term treatment with azathioprine, 6-mercaptopurine, and 6-thioguanine has been correlated with the photoinduced formation of carcinomas. Establishing an in-depth understanding of the photochemical properties of these prodrugs may provide a route to overcoming these carcinogenic side effects, or, alternatively, a basis for developing effective compounds for targeted phototherapy...
July 6, 2018: Photochemistry and Photobiology
Mikkel Bregnhøj, Lea Dichmann, Ciaran K McLoughlin, Michael Westberg, Peter R Ogilby
Uric acid and/or its mono anion have long been used as chemical trapping agents to demonstrate the presence of singlet oxygen, O2 (a1 Δg ), in aqueous systems. "Oxidative bleaching" of uric acid, generally monitored through changes in the uric acid absorption spectrum, is often used in giort of claims for the intermediacy of O2 (a1 Δg ). The bleaching of uric acid has also been used to quantify photosensitized O2 (a1 Δg ) yields in selected systems. Unfortunately, experiments performed to these ends often neglect processes and phenomena that can influence the results obtained...
July 3, 2018: Photochemistry and Photobiology
Makoto Kunisada, Nozomi Yamano, Chieko Hosaka, Chihiro Takemori, Chikako Nishigori
Voriconazole is an anti-fungal agent and used as a prophylactic measure, especially in immunocompromised patients. However, there have been several reports of its adverse reactions, namely photosensitivity with intense inflammatory rashes and subsequent skin cancer development. To assess the effects of photosensitizing drugs voriconazole and hydrochlorothiazide (HCTZ) on the enhancement of UV-induced inflammatory responses and UV-induced tumorigenesis, we utilized Xpa-knockout mice, which is DNA repair-deficient and more susceptible to UV-induced inflammation and tumor development than wild-type mice...
July 3, 2018: Photochemistry and Photobiology
Renzo P Zanocco, Silvana Valdebenito, Yasser Gidi, Gerald Zapata-Torres, Else Lemp, Santi Nonell, Antonio L Zanocco
Naphthoxazole derivatives are small heterocyclic compounds endowed with outstanding fluorescence properties. In this work we report a detailed study of the intense white-light fluorescence observed in naphthoxazole-quinoline dyads in solvent mixtures including at least a strong hydrogen-bonding solvent. The same phenomenon was also studied in inclusion complexes naphthoxazole derivatives - sulfonated-βCD either in aqueous solution as well as in solid phase. A novel mechanism of white molecular fluorescence generation based on solvent-to-fluorophore proton transfer facilitated by ground-state hydrogen-bonding was characterized...
July 2, 2018: Photochemistry and Photobiology
Mojtaba Bagherzadeh, Reyhaneh Kaveh
New magnetically separable CaFe2 O4 /Ag3 PO4 , MgFe2 O4 /Ag3 PO4 , rGO/CaFe2 O4 /Ag3 PO4 and rGO/MgFe2 O4 /Ag3 PO4 photocatalysts synthesized by the hydrothermal and ion-exchange deposition method. These four types of photocatalyst were used for degradation of Methylene blue (MB), Methyl orange (MO) and 4-chlorophenol (4-CP) in aqueous solution under visible-light illumination. The optimized photocatalyst, i.e. rGO/CaFe2 O4 /Ag3 PO4 with a mass ratio of (1:3:9) composite not only shows the highest photocatalytic performance for the degradation of MB, MO and 4-CP under visible light irradiation among the other synthesized photocatalysts but also exhibits high reusability and stability for at least 5 cycles...
July 1, 2018: Photochemistry and Photobiology
Albert W Girotti, Witold Korytowski
Like other unsaturated lipids in cell membranes and lipoproteins, cholesterol (Ch) is susceptible to oxidative modification, including photodynamic oxidation. There is a sustained interest in the pathogenic properties of Ch oxides such as those generated by photooxidation. Singlet oxygen (1 O2 )-mediated Ch photooxidation (Type II mechanism) gives rise to three hydroperoxide (ChOOH) isomers: 5α-OOH, 6α-OOH, and 6β-OOH, the 5α-OOH yield far exceeding that of the others. 5α-OOH detection is relatively straightforward and serves as a definitive indicator of 1 O2 involvement in a reaction, photochemical or otherwise...
July 1, 2018: Photochemistry and Photobiology
Raymond E Borg, Jonathan Rochford
Photoacoustic imaging (PAI) is a rapidly growing field which offers high spatial resolution and high contrast for deep-tissue imaging in vivo. PAI is non-ionizing, non-invasive and combines the optical resolution of fluorescence imaging with the spatial resolution of ultrasound imaging. In particular, the development of exogenous PA contrast agents has gained significant momentum of late with a vastly expanding complexity of dye materials under investigation ranging from small molecules, to macromolecular proteins, polymeric and inorganic nanoparticles...
June 28, 2018: Photochemistry and Photobiology
Pâmela O Ornellas, Leonardo S Antunes, Paula C Motta, Caroline Mendonça, Helvécio Póvoa, Karla Fontes, Natalia Iorio, Lívia A A Antunes
This study aimed to evaluate the use of antimicrobial photodynamic therapy (aPDT) as an adjunct for minimally invasive treatment (partial removal of carious tissue - PRCT) of deciduous carious tissue evaluating its efficacy in reducing microorganisms. For that, a clinical study was design including children with deciduous molars with active deep caries lesions (DCL). PRCT was performed and remaining dentin was treated with 100 μg/mL methylene blue solution (5 min) and than irradiated with a low power laser emitting red light (InGaAIP - indium gallium aluminum phosphide; λ = 660nm; 100mW; 300 J/cm²; 90s; 9J)...
June 20, 2018: Photochemistry and Photobiology
Liang Guo, Jiechao Ge, Pengfei Wang
Conjugated polymer dots (Pdots, also named polymer nanoparticles, PNPs), which consist of π-conjugated organic polymers, are novel organic nanomaterials with size in the range of 1-100 nm. Compared with traditional organic small molecules, semiconductor quantum dots, and inorganic nanomaterials, the Pdots exhibit significant potential applications in biological imaging, sensing and detection, drug delivery, and theranostics, due to their advantages of special optical properties, diverse structure, easy surface modification, and good biocompatibility...
June 13, 2018: Photochemistry and Photobiology
Shuhui Ma, Zixu Wang, Jing Cao, Yulan Dong, Yaoxing Chen
The avian circadian system is a complex of mutually coupled pacemakers residing in pineal gland, retina and suprachiasmatic nucleus. In this study, the self-regulation mechanism of pineal circadian rhythm was investigated by culturing chick primary pinealocytes exposed to red light (RL), green light (GL), blue light (BL), white light (WL) and constant darkness (DD), respectively. All illuminations were set up with a photoperiod of 12 light: 12 dark. The 24-h expression profiles of seven core clock genes (cBmal1/2, cClock, cCry1/2, and cPer2/3), cAanat and melatonin showed significant circadian oscillation in all groups, except for the loss of cCry1 rhythm in BL...
June 13, 2018: Photochemistry and Photobiology
Mark P Little, Zaria Tatalovich, Martha S Linet, Michelle Fang, Gerald M Kendall, Michael G Kimlin
Solar ultraviolet radiation is the primary risk factor for skin cancers and sun-related eye disorders. Estimates of individual ambient ultraviolet irradiance derived from ground-based solar measurements and from satellite measurements have rarely been compared. Using self-reported residential history from 67,189 persons in a nationwide occupational US radiologic technologists cohort, we estimated ambient solar irradiance using data from ground-based meters and noontime satellite measurements. The mean distance-moved from city of longest residence in childhood increased from 137...
June 13, 2018: Photochemistry and Photobiology
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