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Sample records for haematoporphyrin derivative photosensitized

  1. Uptake and distribution of haematoporphyrin derivative in the unicellular eukaryote Paramecium.

    Science.gov (United States)

    Croce, A C; Wyroba, E; Bottiroli, G

    1990-08-01

    Haematoporphyrin derivative (HpD) uptake, intracellular distribution and turnover were examined in a free-living protozoan cell, Paramecium aurelia, which had been demonstrated to internalize lipoproteins. A 10 min incubation in HpD completed with low-density lipoprotein (LDL) resulted in the appearance of distinct red-fluorescing vesicles, together with a diffuse fluorescence of the cytoplasm. Fluorescein labelling of LDL demonstrated the intracellular localization of HpD and LDL within the same vesicles. Pretreatment of Paramecium with the β-adrenergic antagonist l-propranolol, which blocked its phagocytotic activity, resulted in an absence of red-fluorescing vesicles; thus these were proved to be endosomes. Fluorescence emission recorded in the endosomes was characterized by a band at about 660-670 nm which was attributed to the partially unfolded oligomers; this emission was present during maintenance of the cells in drug-free culture medium for up to 120 min. Propranolol-pretreated cells exhibited only a diffuse cytoplasmic fluorescence characterized by an emission band at 630 nm, which was attributed to the monomers; this disappeared rapidly on washing. These results suggest the following: (i) HpD monomers enter Paramecium via transmembrane influx and/or fluid phase uptake; (ii) HpD oligomers are mainly internalized via receptor-mediated endocytosis; (iii) the extent of the endocytotic process is increased when HpD is completed with LDL; (iv) after internalization, aggregate species undergo a disaggregating process which accounts for the persistence of the intracellular fluorescence.

  2. Nile Blue derivatives as lysosomotropic photosensitizers

    Science.gov (United States)

    Lin, Chi-Wei; Shulok, Janine R.; Kirley, S. D.; Cincotta, Louis; Foley, James W.

    1991-06-01

    The benzophenoxazines, including several Nile blue analogues, are a unique group of dyes that localize selectively in animal tumors. Chemical modifications of Nile blue A can yield derivatives with high 1O2 quantum yields. These derivatives represent a group of potentially effective photosensitizers for selective phototherapy of malignant tumors. In vitro evaluation of these derivatives has indicated that those with high 1O2 yields are very effective in mediating the photocytotoxicity of tumor cells. This photodynamic effect is most likely mediated through the action of 1O2, since photoirradiation under D2O enhanced and under hypoxic conditions diminished the photocytotoxic action. The subcellular localization of these photosensitizers in bladder tumor cells in culture was examined by light and fluorescence microscopies as well as by histochemical and biochemical studies. The results indicate that these dyes are localized primarily in the lysosome. The cellular uptake and retention of these dyes is energy- and pH-dependent. Agents such as nigericin, which alter the transmembrane pH gradient, reduced uptake and enhanced efflux of the dyes, while agents such as valinomycin, which reduce cellular membrane potential, had no effect on the uptake. These findings are consistent with having ion-trapping as the mechanism for the uptake of these dyes. Photoirradiation of sensitizer-treated cells obliterated lysosomes in a light-dose and drug-dose dependent fashion. Release of the hydrolytic enzymes may be the main cause for subsequent cell death since the cytolytic effect was reduced by a specific inhibitor of lysosomal proteolytic enzyme. A lysosomotropic photosensitization mechanism is therefore proposed for the photocytotoxic action of the Nile blue derivatives. This mechanism may provide an approach to the development of new photosensitizers for the effective and selective destruction of malignant tumors.

  3. Smart photovoltaics based on dye-sensitized solar cells using photochromic spiropyran derivatives as photosensitizers

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Shengbo; Ting, Hungkit; Ma, Yingzhuang; Zheng, Lingling; Zhang, Miwei [State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Xiao, Lixin, E-mail: zjchen@pku.edu.cn, E-mail: lxxiao@pku.edu.cn; Chen, Zhijian, E-mail: zjchen@pku.edu.cn, E-mail: lxxiao@pku.edu.cn [State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Haixi Collaborative Innovation Center for New Display Devices and Systems Integration, Fuzhou University, Fuzhou 350002 (China)

    2015-05-15

    In this paper, smart photovoltaic (SPV) devices, integrating both functions of solar cells and smart windows, was fabricated based on dye-sensitized solar cells using photochromic spiropyran derivatives SIBT as photosensitizers. SPV devices have self-regulated power conversion efficiency (PCE) and light transmission responding to the incident spectra due to the photoisomerization of SIBT. SIBT isomerize from closed-ring form to open-ring form under UV illumination, accompanied with enhanced visible light absorption and electron delocalization. Therefore, increased PCE and absorption in SPV devices were observed under UV treatment and the devices can be restored gradually to the initial status when kept in dark. The SPV devices have self-regulation of PCE and sunlight transmission responding to the changing sun spectra in different times of a day, providing a proper energy usage and a better sun-shading.

  4. Phytoalexin Phenalenone Derivatives Inactivate Mosquito Larvae and Root-knot Nematode as Type-II Photosensitizer

    Science.gov (United States)

    Song, Runjiang; Feng, Yian; Wang, Donghui; Xu, Zhiping; Li, Zhong; Shao, Xusheng

    2017-02-01

    Phytoalexins phenalenones (PNs) are phytochemicals biosynthesized inside the plant in responsive to exterior threat. PNs are excellent type-II photosensitizers, which efficiently produce singlet oxygen upon light irradiation. Based on the core functional structure of PNs, novel PN derivatives were synthesized here and their singlet oxygen generating abilities and their phototoxicity were evaluated. At the presence of light, these PNs have photoinduced toxicity towards Aedes albopictus larvae and nematode Meloidogyne incognita, while the activity lost in the dark. The obvious tissue damage was observed on the treated mosquito larvae and nematode due to the generation of singlet oxygen. Our results revealed the potential of phenalenones as photoactivated agents for mosquito and root-knot nematode management together with light.

  5. Development of a topical hematoporphyrin derivative formulation: characterization of photosensitizing effects in vivo

    Energy Technology Data Exchange (ETDEWEB)

    McCullough, J.L.; Weinstein, G.D.; Lemus, L.L.; Rampone, W.; Jenkins, J.J.

    1983-12-01

    Photochemotherapy offers a unique approach for the selective therapy of skin diseases. Hematoporphyrin derivative (HPD) in combination with visible light exhibits cytocidal activity in vitro and systemically has demonstrated applicability to the treatment of experimental and human tumors. This study was undertaken to investigate the phototoxic effects in guinea pig skin of systemic HPD in comparison with locally (intradermal) and topically administered HPD. Maximum erythema was obtained by irradiation with red light or UVA 6 h postsystemic HPD (10 mg/kg). Erythema response was dependent upon the dose of irradiation. Systemic HPD produced complete inhibition of epidermal DNA, RNA, and protein synthesis 6-12 h postirradiation with red light, with a lesser degree of inhibition in the deeper hair roots. Local (intradermal) HPD (5-500 micrograms) in combination with red light or UVA produced a dose-dependent erythema and inhibition of epidermal DNA synthesis. Effective in vitro percutaneous penetration of HPD was demonstrated in vehicles containing Azone and N-methylpyrrolidone. Topical application of these HPD formulations in vivo in combination with red light or UVA produced significant erythema and inhibition of epidermal DNA synthesis. These results suggest that HPD can cause photosensitization of the skin. It may therefore be reasonable to explore topical applications as an alternative approach for the photochemotherapy of psoriasis and other cutaneous diseases.

  6. 131I-Zn-Chlorophyll derivative photosensitizer for tumor imaging and photodynamic therapy.

    Science.gov (United States)

    Ocakoglu, Kasim; Er, Ozge; Kiyak, Guven; Lambrecht, Fatma Yurt; Gunduz, Cumhur; Kayabasi, Cagla

    2015-09-30

    In recent years, the photodynamic therapy studies have gained considerable attention as an alternative method to surgery, chemotherapy and radiotherapy which is commonly used to fight cancer. In this study, biological potentials of a benzyloxy bearing zinc(II) pheophorbide-a (Zn-PH-A) were investigated via in vivo and in vitro experiments. Zn-PH-A was labeled with (131)I with high efficiency (95.3 ± 2.7%) and its biodistribution studies were investigated on female Albino Wistar rats. The radiolabeled photosensitizer had been intravenously injected into the tail vein, and then the animals were sacrificed at 30, 60 and 120 min post injection. The percent of radioactivity per gram of organs (%ID/g) was determined. The radiolabeled Zn-PH-A showed high uptake in ovary. In addition, photodynamic therapy studies of the photosensitizer were conducted in EMT6, murine mammary carcinoma and HeLa, human cervix carcinoma cell lines. For the photodynamic therapy studies, the cells with Zn-PH-A were exposed to red light (650 nm) at the doses of 10-30 J/cm(2). The results showed that Zn-PH-A has stronger PDT effect in EMT6 than HeLa cell. Our present work demonstrates (131)I-labeled photosensitizer as a bifunctional agent (PDT and nuclear imaging) which could be improved in future by using EMT6 growing tumor in nude mice.

  7. Photosensitization of Nanocrystalline TiO2 Electrode Modifiedwith C60 Carboxylic Acid Derivatives

    Institute of Scientific and Technical Information of China (English)

    张文; 史亚茹; 甘良兵; 黄春辉; 王艳琴; 虎民

    2001-01-01

    C60 carboxylic acid derivatives can be readily adsorbed on the surface of nanocrystalline TiO2 films act as charge-transfer sensitizer. The electron transport from TiO2 to the C60 derivatives results in the generation of the cathodic photocurrent. The short-circuit photocurrent of a C60 tetracarboxylic acid is 0.45 μA/cm2 under 464 um light illumination. The photoelectric behaviour of ITO electrodes modified by the same C60 carboxylic acids is different from that of the modified TiO2 electrodes, and shows anodic photocurrent.

  8. Artificial photosynthesis. 1. Photosensitization of TiO[sub 2] solar cells with chlorophyll derivatives and related natural porphyrins

    Energy Technology Data Exchange (ETDEWEB)

    Kay, A.; Graetzel, M. (Ecole Polytechnique Federale de Lausanne (Switzerland))

    1993-06-10

    Colloidal TiO[sub 2] electrodes were photosensitized with derivatives of chlorophyll and related natural porphyrins resulting in light harvesting and charge separation efficiencies comparable to those in natural photosynthesis. The photocurrent action spectra of the electrodes correlate well with the absorption spectra of the dyes in solution. Incident photon to current efficiencies up to 83% are reached in the Soret peak at 400 nm with a 12-[mu]m-thick TiO[sub 2] film sensitized by copper mesoporphyrin IX, which corresponds to nearly unity quantum efficiency of charge separation when light reflection losses are taken into account. Photocurrent/voltage curves of TiO[sub 2] solar cells sensitized with copper chlorophyllin show an energy conversion efficiency of 10% for the red peak at 630 nm. Under simulated sunlight illumination, an open circuit photovoltage of 0.52 V and a short circuit current density of 9.4 mA/cm[sup 2] are measured. The overall energy conversion efficiency of the cell is 2.6% under these conditions, in part limited by ohmic losses at such high current densities. The comparison of different chlorophyll derivatives indicates that free carboxyl groups are important for adsorption and sensitization on TiO[sub 2]. However, conjugation of the carboxyl groups with the [pi] electron system of the chromophore is not necessary for efficient electron transfer. Free bases, zinc, and even the nonfluorescent copper complexes of chlorophyllins and mesoporphyrin IX are efficient sensitizers for TiO[sub 2]. Cholanic acids as coadsorbates were found to be unique in improving both photocurrent and voltage of copper chlorophyllin sensitized cells. This effect is discussed by comparison with other coadsorbates. 23 refs., 3 figs., 1 tab.

  9. Molecular Tuning of Phenylene-Vinylene Derivatives for Two-Photon Photosensitized Singlet Oxygen Production

    DEFF Research Database (Denmark)

    Nielsen, Christian B.; Arnbjerg, Jacob; Johnsen, Mette

    2009-01-01

    that can deviate from the norm, a full investigation of the photophysical properties of the system is generally required. For example, it is acknowledged that the introduction of a ketone moiety to the sensitizer chromophore often results in more efficient production of singlet oxygen. However, we show...... here that the introduction of a carbonyl into a given phenylene-vinylene can, rather, have adverse effects on the yield of singlet oxygen produced. Using these molecules, we show that care must also be exercised when using qualitative symmetry-derived arguments to predict the relationship between one...

  10. Two new phloroglucinol derivatives and five photosensitizing pheophorbides from Syzygium polyanthum leaves (Salam).

    Science.gov (United States)

    Har, Lee Wei; Shaari, Khozirah; Boon, Lee Hong; Kamarulzaman, Fadzly A; Ismail, Intan S

    2012-08-01

    Two new phloroglucinol derivatives, identified as anthuminoate (1) and anthuminone (2), were isolated from the ichthyotoxic ethyl acetate fraction of Syzygium polyanthum leaves. In addition, bioassay-guided fractionation followed by dereplication of the photocytotoxic fraction of this plant part has resulted in the identification of five known pheophorbides as the bioactive constituents. The compounds were identified as pheophorbide-a, methyl pheophorbide-a, methyl hydroxypheophorbide-a, pheophorbide-b and hydroxypheophorbide-b. Inhibition of cell viability shown by the compounds ranged from 83.3 to 86.1% at a test concentration of 5 microg/mL. This shows that Syzygium polyanthum leaves are a potential new source in the studies of photocytotoxicity for photodynamic therapy.

  11. Organometallic Ru(II) Photosensitizers Derived from π-Expansive Cyclometalating Ligands: Surprising Theranostic PDT Effects.

    Science.gov (United States)

    Sainuddin, Tariq; McCain, Julia; Pinto, Mitch; Yin, Huimin; Gibson, Jordan; Hetu, Marc; McFarland, Sherri A

    2016-01-04

    The purpose of the present study was to investigate the influence of π-expansive cyclometalating ligands on the photophysical and photobiological properties of organometallic Ru(II) compounds. Four compounds with increasing π conjugation on the cyclometalating ligand were prepared, and their structures were confirmed by HPLC, 1D and 2D (1)H NMR, and mass spectrometry. The properties of these compounds differed substantially from their Ru(II) polypyridyl counterparts. Namely, they were characterized by red-shifted absorption, very weak to no room temperature phosphorescence, extremely short phosphorescence state lifetimes ( 300 μM) but was phototoxic to cells in the nanomolar regime. Exceptionally large phototherapeutic margins, exceeding 3 orders of magnitude in some cases, were accompanied by bright ligand-centered intracellular fluorescence in cancer cells. Thus, Ru(II) organometallic systems derived from π-expansive cyclometalating ligands, such 4,9,16-triazadibenzo[a,c]napthacene (pbpn), represent the first class of potent light-responsive Ru(II) cyclometalating agents with theranostic potential.

  12. Improved photosensitizers for photodynamic therapy

    Science.gov (United States)

    Pandey, Ravindra K.; Shiau, Fuu-Yau; Meunier, Isabelle; Ramaprasad, Subbaraya; Sumlin, Adam B.; Dougherty, Thomas J.; Smith, Kevin M.

    1992-06-01

    In order to evaluate the effect of substituents in photosensitizing activity, a series of long wavelength absorbing photosensitizers related to pyropheophorbides, bacteriopheophorbides, and benzoporphyrin derivatives were synthesized. Pheophorbide dimers, covalently joining two molecules of pyropheophorbide-a and bacteriopheophorbide-a with lysine as a cross-link were also prepared. The syntheses and spectroscopic properties of these compounds are discussed. Some of these compounds were tested for in vivo photosensitizing activity vis-a-vis Photofrin IITM, using the standard screening system of DBA/2 mice bearing transplanted SMT/F tumors. The preliminary in vivo results suggest that replacement of substituents at peripheral positions of the macrocycles causes a significant difference in photosensitizing efficacy.

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

    Science.gov (United States)

    Hirakawa, Kazutaka; Murata, Atsushi

    2017-07-31

    Water-soluble porphyrins, diethoxyphosphorus(V)tetraphenylporphyrin (EtP(V)TPP) and its fluorinated analogue (FEtP(V)TPP), decreased the typical absorption around 340nm of nicotinamide adenine dinucleotide (NADH) under visible light irradiation, indicating oxidative decomposition. A singlet oxygen quencher, sodium azide, and a triplet quencher, potassium iodide, slightly inhibited photosensitized NADH oxidation. However, these inhibitory effects were very small. Furthermore, the fluorescence lifetime of these P(V)porphyrins was decreased by NADH, suggesting the contribution of electron transfer to the singlet excited (S1) state of P(V)porphyrin. The redox potential measurement supports the electron transfer-mediated oxidation of NADH. The quantum yields of NADH photodecomposition by P(V)porphyrins could be estimated from the kinetic data and the effect of these quenchers on NADH oxidation. The obtained values suggest that the electron accepting by the S1 states of P(V)porphyrins triggers a chain reaction of NADH oxidation. This photosensitized reaction may play an important role in the photocytotoxicity of P(V)porphyrins. The axial ligand fluorination of P(V)porphyrins improved electron accepting ability. However, fluorination slightly suppressed static interaction with NADH, resulting in decreased oxidation quantum yield. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Tumour destruction and proliferation kinetics following periodic, low power light, haematoporphyrin oligomers mediated photodynamic therapy in the mouse tongue.

    Science.gov (United States)

    Pe, M B; Ikeda, H; Inokuchi, T

    1994-05-01

    Photodynamic therapy (PDT) is an experimental modality in the treatment of cancer. It involves photochemical reactions that require the interaction of a photosensitising drug, light and oxygen. The development of an efficient protocol based on assuring oxygen availability through modulation of the incident light power density and its mode of delivery was addressed in this study. An estimated energy dose of 180 J/cm2 of 630 nm light from pulsed Nd:YAG dye laser was delivered 24 h after injection of 10 mg/kg haematoporphyrin oligomers in C3H/HeNCrj mice bearing the transplantable squamous cell carcinoma NR-S1, by either of these light regimens: (1) 5 mJ/cm2/pulse for 30 min, 1 h dark interval, followed by another 30 min exposure to the same power (low power, periodic light regimen) or (2) 15 mJ/cm2/pulse for 20 min (high power, continuous light regimen). Results showed a higher mean percentage area of tumour destruction with the low power, periodic light regimen at 54.34% in contrast to 12.44% of the high power, continuous light regimen 2 days after PDT. Furthermore, the mean bromodeoxyuridine labelling indices of the remaining viable-appearing cancer cells were 27.90 and 42.41, respectively, indicating a smaller tumour growth fraction with the former regimen. These results suggest that use of low power, periodically delivered light increases the antitumour efficacy of PDT.

  15. Pentosan-derived water-soluble carbon nano dots with substantial fluorescence: Properties and application as a photosensitizer

    Science.gov (United States)

    Wu, Qiong; Li, Wei; Wu, Yanjiao; Huang, Zhanhua; Liu, Shouxin

    2014-10-01

    The hydrothermal carbonization of monosaccharides and polysaccharides is widely used in the production of carbonaceous material with a desired structure. However, the liquid products are regarded as waste and discarded. Here, we report a facile approach for the synthesis of water-soluble carbon nano dots (CNDs) with substantial fluorescence from the liquid by-products of the hydrothermal carbonization of pentosan, thus the by-products of pulp refining. The synthesized CNDs are monodispersed spheres with abundant oxygen-containing groups and they have an average size of 30 nm. Quantum yield measurements revealed CNDs with substantial green photoluminescence (PL) without passivation. Additionally, excitation was independent, pH-sensitive and stable. The use of CNDs as a photosensitizer in the CNDs/TiO2 system for methylene blue (MB) degradation under visible light irradiation is attractive. The spectral response range of the CNDs/TiO2 system can be widened from the UV region to a part of the visible light region (400-550 nm).

  16. Pentosan-derived water-soluble carbon nano dots with substantial fluorescence: Properties and application as a photosensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Li, Wei; Wu, Yanjiao; Huang, Zhanhua; Liu, Shouxin, E-mail: liushouxin@126.com

    2014-10-01

    Graphical abstract: Water-soluble carbon nano dots (CNDs) with high fluorescence are synthesized from liquid by-products of hydrothermal carbonization of pentosan, the by-products of pulp refining. CNDs can be effectively used as photo sensitizer in the CNDs/TiO{sub 2} system for methyl blue (MB) degradation under visible light irradiation, spectral response range of CNDs/TiO{sub 2} system can be widen from only UV region to part visible-light region (400–550 nm). - Highlights: • Water-soluble CNDs with abundant oxygen-containing groups can be obtained from the liquid by-products of hydrothermal carbonization of pentosan. • CNDs show excellent photoluminescence, pH sensitivity as well high stability. • CNDs/TiO{sub 2} system can be used as visible-light catalysts for the degradation of MB effectively. - Abstract: The hydrothermal carbonization of monosaccharides and polysaccharides is widely used in the production of carbonaceous material with a desired structure. However, the liquid products are regarded as waste and discarded. Here, we report a facile approach for the synthesis of water-soluble carbon nano dots (CNDs) with substantial fluorescence from the liquid by-products of the hydrothermal carbonization of pentosan, thus the by-products of pulp refining. The synthesized CNDs are monodispersed spheres with abundant oxygen-containing groups and they have an average size of 30 nm. Quantum yield measurements revealed CNDs with substantial green photoluminescence (PL) without passivation. Additionally, excitation was independent, pH-sensitive and stable. The use of CNDs as a photosensitizer in the CNDs/TiO{sub 2} system for methylene blue (MB) degradation under visible light irradiation is attractive. The spectral response range of the CNDs/TiO{sub 2} system can be widened from the UV region to a part of the visible light region (400–550 nm)

  17. Susceptibility of representative dental pathogens to inactivation by the PDT with water-soluble photosensitizers

    Science.gov (United States)

    Angelov, Ivan; Mantareva, Vanya; Kussovski, Veselin; Worle, Diter; Kisov, Hristo; Belcheva, Marieta; Georgieva, Tzvetelina; Dimitrov, Slavcho

    2011-02-01

    In the recent decade the applications of photodynamic therapy (PDT) rapidly increase in several topics and one of areas where the PDT in the future will be play significant role is dentistry. The different photosensitizing complexes with a good water solubility and with absorption with an intensive maximum in the red region (630-690 nm), which makes them suitable for photodynamic treatments, were investigated. The photochemical properties of complexes for singlet oxygen generation were investigated and were shown relations between uptake levels and light intensity to achieve increase in photodynamic efficacy. Photodynamic efficacy against fungi Candida albicans and bacteria's E. faecalis, MRSA and S. Mutans in planktonic media was evaluated. The high photodynamic efficacy was shown for SiPc at very low concentrations (0.9 μM) and light doses of 50 J cm-2 by intensity of light 60 mW cm-2. The photodynamic response for E. faecalis, MRSA and S. Mutans, after treatments with different photosensitizers show strong dependence on concentrations of photsensitzers and micro organisms. The level of inactivation of the pathogen bacteria's from 1-2 degree of initial concentration up to full inactivation was observed. The studied complexes were compared to the recently studied Methylene blue, Haematoporphyrine and tetra-methylpirydiloxy Zn(II)- phthalocyanines and experimental results show that some of them have a good potential for inactivation of representative pathogenic bacterial strains. Experimental results also indicate that photodynamic therapy appears an effective method for inactivation of oral pathogenic bacterias and fungi.

  18. A blocked diketo form of avobenzone: photostability, photosensitizing properties and triplet quenching by a triazine-derived UVB-filter.

    Science.gov (United States)

    Paris, Cecilia; Lhiaubet-Vallet, Virginie; Jiménez, Oscar; Trullas, Carles; Miranda, Miguel Angel

    2009-01-01

    Novel sunscreens are required providing active protection in the UVA and UVB regions. On the other hand, there is an increasing concern about the photosafety of UV filters, as some of them are not sufficiently photostable. Avobenzone is one of the most frequently employed sunscreen ingredients, but it has been reported to partially decompose after irradiation. In the present work, photophysical and photochemical studies on a methylated avobenzone-derivative have shown that the diketo form is responsible for photodegradation. A transient absorption was observed at 380 nm after laser flash photolysis excitation at 308 nm. It was assigned to the triplet excited state of the diketo form, as inferred from quenching by oxygen and beta-carotene. This transient also interacted with key building blocks of biomolecules by triplet-triplet energy transfer (in the case of thymidine) or electron transfer processes (for 2'-deoxyguanosine, tryptophan and tyrosine). Irradiation of the avobenzone derivative in the presence of a triazine UV-B filter (E-35852) diminished the undesirable effects of the compound by an efficient quenching of the triplet excited state. Thus, sunscreen formulations including triplet quenchers could provide effective protection from the potential phototoxic and photoallergic effects derived from poor photostability of avobenzone.

  19. Temporal characteristics of polarization holographic gratings formed in a photosensitive polymeric film containing N-benzylideneaniline derivative side groups

    Science.gov (United States)

    Sasaki, Tomoyuki; Shoho, Takashi; Noda, Kohei; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2014-04-01

    A polarization holographic grating was recorded in a transparent thin film formed from polymethacrylate with N-benzylideneaniline (NBA) derivative side groups. We measured the real time diffraction properties. The data were analyzed based on a theoretical model that accounted for the distribution of optical anisotropy caused by molecular reorientation as well as for surface relief (SR) deformation caused by molecular motion. Optical anisotropy rapidly increased and then slowly decreased, with increasing recording time. This phenomenon was described based on photoisomerization and photocleavage reactions of the NBA side groups. SR deformation was also induced in the film by polarization holographic recording, without any subsequent processes. The photoinduced optical anisotropy and SR deformation were retained after the recording was turned off.

  20. Photophysical and photosensitive properties of Elsinochrome A

    Institute of Scientific and Technical Information of China (English)

    LI Cong; HE Yanping; OU Lingcheng; TIAN Maojun; YAO Zhikun; GUO Mengbi

    2006-01-01

    In this paper, the photophysical and photosensitive properties of Elsinochrome A (EA),another member of perylenequinone photosensitizers derived via artificially biological synthesis, were studied by taking hypocrellin A (HA) and hypocrellin B (HB) as the references. It was found that the quantum yield of singlet oxygen produced via the photosensitization of EA was 0.98 with HB (0.84) as a reference.Furthermore, the semiquinone anion could be produced via photosensitization of EA in oxygen-free solution. Besides, taking advantage of nanosecond time-resolved spectral technique, the transient triplet absorption spectra and the lifetime of EA in cyclohexane were determined by the use of the groundstate depletion method.

  1. Organic photosensitive devices

    Science.gov (United States)

    Rand, Barry P; Forrest, Stephen R

    2013-11-26

    The present invention generally relates to organic photosensitive optoelectronic devices. More specifically, it is directed to organic photosensitive optoelectronic devices having a photoactive organic region containing encapsulated nanoparticles that exhibit plasmon resonances. An enhancement of the incident optical field is achieved via surface plasmon polariton resonances. This enhancement increases the absorption of incident light, leading to a more efficient device.

  2. Inverted organic photosensitive devices

    Energy Technology Data Exchange (ETDEWEB)

    Forrest, Stephen R.; Bailey-Salzman, Rhonda F.

    2016-12-06

    The present disclosure relates to organic photosensitive optoelectronic devices grown in an inverted manner. An inverted organic photosensitive optoelectronic device of the present disclosure comprises a reflective electrode, an organic donor-acceptor heterojunction over the reflective electrode, and a transparent electrode on top of the donor-acceptor heterojunction.

  3. Organic photosensitive devices

    Energy Technology Data Exchange (ETDEWEB)

    Rand, Barry P; Forrest, Stephen R

    2013-11-26

    The present invention generally relates to organic photosensitive optoelectronic devices. More specifically, it is directed to organic photosensitive optoelectronic devices having a photoactive organic region containing encapsulated nanoparticles that exhibit plasmon resonances. An enhancement of the incident optical field is achieved via surface plasmon polariton resonances. This enhancement increases the absorption of incident light, leading to a more efficient device.

  4. Photosensitization in biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Spikes, J.D.

    1976-01-01

    Our symposium examines the current status of our knowledge of the photosensitized reactions of nucleic acids and proteins. Significant advances have been made in this area of photobiology since the last international Congress. The first paper will explore the role of molecular oxygen in photosensitized reactions of proteins and nucleic acids. The last three papers are concerned primarily with photosensitized reactions of nucleic acids and their components in which the sensitizer is consumed by bonding covalently with the substrate on irradiation. The best understood reactions of this type are those sensitized by furocoumarins such as 5-methoxypsoralen. These sensitizers show promise in the photochemotherapeutic treatment of proliferative diseases of the skin, such as psoriasis.

  5. Photosensitive human syndromes.

    Science.gov (United States)

    Spivak, Graciela; Hanawalt, Philip C

    2015-06-01

    Photosensitivity in humans can result from defects in repair of light-induced DNA lesions, from photoactivation of chemicals (including certain medications) with sunlight to produce toxic mediators, and by immune reactions to sunlight exposures. Deficiencies in DNA repair and the processing of damaged DNA during replication and transcription may result in mutations and genomic instability. We will review current understanding of photosensitivity to short wavelength ultraviolet light (UV) due to genetic defects in particular DNA repair pathways; deficiencies in some are characterized by an extremely high incidence of cancer in sun-exposed tissues, while in others no cancers have been reported.

  6. Artificial photosynthesis. 2. Investigation on the mechanism of photosensitization of nanocrystalline TiO[sub 2] solar cells by chlrophyll derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Kay, A.; Humphry-Baker, R.; Graetzel, M. (Ecole Polytechnique Federale de Lausanne (Switzerland))

    1994-01-20

    The mechanism of photosensitization of colloidal TiO[sub 2] electrodes with chlorin e[sub 6] and copper chlorophyllin is deduced from static and time-resolved fluorescence quenching as well as laser flash photolysis and photocurrent/voltage transients in combination with cyclic voltammetry and spectroelectrochemistry. The fluorescence of chlorin e[sub 6] on TiO[sub 2] decays to 80% within 0.4 ns, indicating efficient electron injection from the singlet excited state with k[sub et] = 2.2 x 10[sup 9] s[sup [minus]1]. Copper chlorophyllin emits only from the triplet state, due to subpicosecond intersystem crossing in the presence of the paramagnetic Cu[sup 2+] center. Its phosphorescence is strongly enhanced by immobilization on a nonquenching ZrO[sub 2] reference adsorbent, but quenched on TiO[sub 2], indicating electron transfer from the triplet state with k[sub et] = 3 x 10[sup 8] s[sup [minus]1]. The energy levels of the excited photosensitizers and the acceptor state density of TiO[sub 2] are determined by cyclic voltammetry. A strong tail of shallow surface states on the colloidal TiO[sub 2] electrodes modifies the classical picture of a conduction band edge. Transient absorption spectra of the electrodes show three equivalent contributions due to dye bleaching, cation radical formation, and conduction band electrons, in accordance with electron injection from the neutral excited dye. 36 refs., 6 figs., 1 tab.

  7. The Tryptophan-Derived Endogenous Aryl Hydrocarbon Receptor Ligand 6-Formylindolo[3,2-b]Carbazole Is a Nanomolar UVA Photosensitizer in Epidermal Keratinocytes.

    Science.gov (United States)

    Park, Sophia L; Justiniano, Rebecca; Williams, Joshua D; Cabello, Christopher M; Qiao, Shuxi; Wondrak, Georg T

    2015-06-01

    Endogenous UVA chromophores may act as sensitizers of oxidative stress underlying cutaneous photoaging and photocarcinogenesis, but the molecular identity of non-DNA key chromophores displaying UVA-driven photodyamic activity in human skin remains largely undefined. Here we report that 6-formylindolo[3,2-b]carbazole (FICZ), a tryptophan photoproduct and endogenous high-affinity aryl hydrocarbon receptor (AhR) agonist, acts as a nanomolar photosensitizer potentiating UVA-induced oxidative stress irrespective of AhR ligand activity. In human HaCaT and primary epidermal keratinocytes, photodynamic induction of apoptosis was elicited by the combined action of solar-simulated UVA and FICZ, whereas exposure to the isolated action of UVA or FICZ did not impair viability. In a human epidermal tissue reconstruct, FICZ/UVA cotreatment caused pronounced phototoxicity inducing keratinocyte cell death, and FICZ photodynamic activity was also substantiated in a murine skin exposure model. Array analysis revealed pronounced potentiation of cellular heat shock, endoplasmic reticulum stress, and oxidative stress response gene expression observed only upon FICZ/UVA cotreatment. FICZ photosensitization caused intracellular oxidative stress, and comet analysis revealed introduction of formamidopyrimidine-DNA glycosylase (Fpg)-sensitive oxidative DNA lesions suppressible by antioxidant cotreatment. Taken together, our data demonstrate that the endogenous AhR ligand FICZ displays nanomolar photodynamic activity representing a molecular mechanism of UVA-induced photooxidative stress potentially operative in human skin.

  8. Photosensitivity to selsun shampoo

    Directory of Open Access Journals (Sweden)

    Mani M

    1994-01-01

    Full Text Available A case of photosensitive dermatitis, occurring after the second application of 2.5% selenium sulphide (Selsun shampoo, Abbot, is reported. The shampoo was diluted to half strength with water, before use. The patient had pityriasis versicolor, with extensive lesions on the covered as well as exposed areas.

  9. Photosensitizing medications and photocarcinogenesis.

    Science.gov (United States)

    O'Gorman, Susan M; Murphy, Gillian M

    2014-02-01

    Photosensitivity is an exaggerated or abnormal response to ultraviolet (UV) or visible light exposure. Many current medications are known photosensitizers; however, the effects of the sensitization can be subclinical and go unnoticed by the person affected. While some of these drugs are used for short and defined periods, others are used indefinitely for the treatment of chronic disease. The question of whether either of these practices translates into an increased risk of skin cancer is an important one. Numerous medications have real, distinct and well-elucidated mechanisms that potentiate the development of skin cancer, while with some medications the mechanism for the observed carcinogenesis remains unclear. In this article we will discuss the clinical, mechanistic and epidemiological evidence supporting photochemical genotoxicity and carcinogenesis.

  10. Search for new photosensitizers in photodynamic therapy

    Directory of Open Access Journals (Sweden)

    E. A. Lukiyanets

    2013-01-01

    Full Text Available The review of photosensityzers for photodynamic therapy and fluorescent diagnosis, which are being developed, investigated and applied in clinical practice in Russia and other countries, is represented. Principal properties of photosensitizers based on derivatives of hematoporfirin, chlorines, phtalocyanines, naphthalocyanines, benzoporphyrins, pheophorbides, porphycenes etc are described. Main drugs based on these agents are listed, the field of clinical application is indicated. Special consideration is given to phtalocyanines derivatives and its structural analogues. In particular Russian photosensitizers developed in Research Institute of Organic Intermediates and Dyes under the Program for development and health care practical assimilation of new methods and means of prevention, diagnosis and treatment of cancer, infection and other hazardous diseases are traversed in the article. Methods of synthesis are described, spectral, physical and biological characteristics of synthesized compounds are shown. 

  11. Visible light-operated saccharide-O{sub 2} biofuel cell based on the photosensitization of chlorophyll derivative on TiO{sub 2} film

    Energy Technology Data Exchange (ETDEWEB)

    Amao, Yutaka; Takeuchi, Yumi [Department of Applied Chemistry, Oita University, Dannoharu 700, Oita 870-1192 (Japan)

    2008-06-15

    The visible light-operated saccharide-O{sub 2} biofuel cell consisting of zinc chlorin-e{sub 6} (ZnChl-e{sub 6}) adsorbed on nanocrystalline TiO{sub 2} layer coated onto optical transparent conductive glass electrode (OTE) as an anode, platinum-coated OTE as a cathode, and the fuel solution containing sucrose as a saccharide, invertase, glucose dehydrogenase (GDH) and NAD{sup +} is studied as a new type biofuel cell. The short-circuit photocurrent (I{sub SC}) and the open-circuit photovoltage (V{sub OC}) of this cell are 9.0 {mu}A cm{sup -2} and 415 mV, respectively. The peaks in the photocurrent action spectrum of this cell are observed at 400 and 800 nm and the incident photon-to-current efficiency (IPCE) values at 400 and 800 nm are estimated to be ca. 17.3% and 10.6%. Thus, a new type of visible light-operated saccharide-O{sub 2} biofuel cell with the visible and near IR photosensitization of ZnChl-e{sub 6} molecules on nanocrystalline TiO{sub 2} film electrode is accomplished. (author)

  12. [Generalized or focal photosensitive epilepsies].

    Science.gov (United States)

    Parain, D

    1998-11-01

    Photosensitivity is defined by a pattern of occipital or more diffuse spikes and waves. Several techniques are needed for exploration: intermittent light stimulation (ILS), patterns, TV-screen, video games. Photosensitivity is a genetic characteristic. Only diffuse spikes and waves induced by ILS are correlated with epilepsy. Pure photogenic epilepsy is characterized by seizures induced by visual stimuli alone, usually by TV-screen. Video games may also have a triggering effect due to the slow-moving patterns or intense brightness. Several epileptic syndromes are associated with photosensitivity with or without visually-induced seizures. These syndromes are most often generalized and idiopathic.

  13. [Photosensitive epilepsy and television epilepsy].

    Science.gov (United States)

    Parain, D; Blondeau, C

    2000-01-01

    Photosensitivity is defined by the appearance of occipital or more diffuse electroencephalographic spikes and waves induced by intermittent light stimulation (ILS), particular patterns, TV-watching, and video games. Photosensitivity is a genetic characteristic. Only the diffuse spikes and waves induced by ILS are correlated with epilepsy. Pure photogenic epilepsy is characterized by seizures which are only visually induced, usually by watching TV. Video games sometimes add a trigger effect due to slowly moving patterns or intense brightness. Several epileptic syndromes are associated with a photosensitivity with or without visually-induced seizures, mainly generalized idiopathic epilepsy.

  14. Probing Photosensitization by Functionalized Carbon Nanotubes

    Science.gov (United States)

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

  15. Preclinical Evaluation Of Photosensitizing Agents

    Science.gov (United States)

    Kessel, David

    1989-06-01

    Methods for the pre-clinical evaluation of new photosensitizing dyes are described. The resulting information can provide useful leads concerning likely modes and sites of localization. But correlations between results obtained in cell culture and in animal tumor models are sufficiently weak to indicate the need for caution in extrapolation of any in vitro result.

  16. Radiation carcinogenesis: radioprotectors and photosensitizers

    Energy Technology Data Exchange (ETDEWEB)

    Fry, R.J.M.

    1982-01-01

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

  17. Photosensitizers for photodynamic immune modulation

    Science.gov (United States)

    North, John R.; Boch, Ronald; Hunt, David W. C.; Ratkay, Leslie G.; Simkin, Guillermo O.; Tao, Jing-Song; Richter, Anna M.; Levy, Julia G.

    2000-06-01

    PDT may be an effective treatment for certain immune-mediated disorders. The immunomodulatory action of PDT is likely a consequence of effects exerted at a number of levels including stimulation of specific cell signaling pathways, selective depletion of activated immune cells, alteration of receptor expression by immune and non-immune cells, and the modulation of cytokine availability. QLT0074, a potent photosensitizer that exhibits rapid clearance kinetics in vivo, is in development for the treatment of immune disorders. In comparison to the well-characterized and structurally related photosensitizer verteporfin, lower concentrations of QLT0074 were required to induce apoptosis in human blood T cells and keratinocytes using blue light for photoactivation. Both photosensitizers triggered the stress activated protein kinase (SAPK) and p38 (HOG1) pathways but not extracellularly regulated kinase (ERK) activity in mouse Pam212 keratinocytes. In cell signaling responses, QLT0074 was active at lower concentrations than verteporfin. For all in vitro test systems, the stronger photodynamic activity of QLT0074 was associated with a greater cell uptake of this photosensitize than verteporfin. In mouse immune models, sub-erythemogenic doses of QLT0074 in combination with whole body blue light irradiation inhibited the contact hypersensitivity response and limited the development of adjuvant-induced arthritis. QLT0074 exhibits activities that indicate it may be a favorable agent for the photodynamic treatment of human immune disease.

  18. Retrospective analysis of drug photosensitivity in Norway

    Science.gov (United States)

    Selvaag, Edgar

    1999-02-01

    Reports on adverse drug reactions, as they were recorded at the Norwegian Medicines Control Authority beginning in the year 1970 up to 1994 were analyzed especially with regard to cutaneous reactions and photosensitivity reactions. During the time period, almost 13.000 side effects were reported. Out of these 799 reports involved the skin and appendages, and 64 out of these reports (8%) were classified as photosensitivity reactions. Tetracyclines, diuretics, antihypertensive agents, and urologicals were the drugs which most often caused photosensitivity reactions. In addition, a number of uncommon photosensitizing drugs were reported. The risk for photosensitization is discussed on the background of experimental data and the prescription rates of these substances.

  19. Photosensitivity: a current biological overview.

    Science.gov (United States)

    Elkeeb, Dena; Elkeeb, Laila; Maibach, Howard

    2012-12-01

    The level of interest in photoirritation (phototoxicity) has increased because of the awareness among the scientific community of the increase in the UV portion of the solar spectrum reaching the earth. The need of new chemicals and drugs puts pressure on pre-test methods for side effects, especially interactive adverse effects with UV light. So pre-marketing clinical trials conducted before a new drug is licensed are essential, as such, at the early phases of the discovery process of the drug/chemical, developing an efficacious photosensitivity testing system is prudent to avoid such potential side effects. To review published literature and provide an overview on exogenous photosensitivity and assays used to evaluate the photosensitivity potential of drugs/chemicals. As well as testing considerations by the Regulatory bodies (namely, the Organization for Economic Cooperation and Development, the U.S Food and Drug Administration and the European Union regulatory agencies). We searched medical and scientific search engines as well as websites of the EU and US Regulatory agencies and used keywords such as cutaneous phototoxicity, phototoxicity in vitro assays, phototoxicity in vivo assays and other related terms.

  20. Drug-delivery and multifunction possibilities of hypocrellin photosensitizers

    Directory of Open Access Journals (Sweden)

    Hong Deng

    2015-01-01

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

  1. "Selfie-epilepsy": A novel photosensitivity.

    Science.gov (United States)

    Brna, P M; Gordon, K G

    2017-04-01

    Photosensitivity is a well-described phenomenon; affecting a relatively small proportion of individuals with epilepsy. Typically people with photosensitive epilepsies are at risk of seizures induced by shimmering natural light, strobe lights and with particular patterns or flicker frequencies on television and video games. We present a novel case of photosensitivity captured during video EEG monitoring showing reproducible photosensitivity with the ever-popular social phenomenon; the "selfie." The patient had previously demonstrated photosensitive myoclonus with intermittent photic stimulation on routine EEG. This case suggests that taking "selfies" may represent a new area of caution for those with photosensitive epilepsies. Copyright © 2017 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

  2. Photosensitized inactivation of infectious blood-borne human parasites

    Science.gov (United States)

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

    1995-05-01

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

  3. Riboflavin photosensitized oxidation of myoglobin.

    Science.gov (United States)

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

    2014-02-05

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

  4. New photosensitizers for photodynamic therapy

    Science.gov (United States)

    Abrahamse, Heidi; Hamblin, Michael R.

    2016-01-01

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

  5. Intrinsically photosensitive retinal ganglion cells

    Institute of Scientific and Technical Information of China (English)

    Gary; E.PICKARD; Patricia; J.SOLLARS

    2010-01-01

    A new mammalian photoreceptor was recently discovered to reside in the ganglion cell layer of the inner retina.These intrinsically photosensitive retinal ganglion cells(ipRGCs) express a photopigment,melanopsin,that confers upon them the ability to respond to light in the absence of all rod and cone photoreceptor input.Although relatively few in number,ipRGCs extend their dendrites across large expanses of the retina making them ideally suited to function as irradiance detectors to assess changes in ambient light levels.Phototransduction in ipRGCs appears to be mediated by transient receptor potential channels more closely resembling the phototransduction cascade of invertebrate rather than vertebrate photoreceptors.ipRGCs convey irradiance information centrally via the optic nerve to influence several functions.ipRGCs are the primary retinal input to the hypothalamic suprachiasmatic nucleus(SCN),a circadian oscillator and biological clock,and this input entrains the SCN to the day/night cycle.ipRGCs contribute irradiance signals that regulate pupil size and they also provide signals that interface with the autonomic nervous system to regulate rhythmic gene activity in major organs of the body.ipRGCs also provide excitatory drive to dopaminergic amacrine cells in the retina,providing a novel basis for the restructuring of retinal circuits by light.Here we review the ground-breaking discoveries,current progress and directions for future investigation.

  6. Bioconjugates of photosensitizers relevant for PDT

    Science.gov (United States)

    Golubeva, N. A.; Demcheva, Marina V.; Chernyaeva, Elena B.; Yakubovskaya, Raisa I.; Suhin, G. M.; Ponomarev, Gelii V.; Galpern, Maria G.; Lukyanets, Eugeny A.; Savitsky, Alexander P.

    1996-01-01

    The photodynamic therapy is highly promising for its dual specificity, namely, for the site of accumulation of the phototoxic substance and for the site of action of laser. A drawback of the PDT technique is a low selectivity of the photosensitizers accumulation in tumor tissue. Therapeutic doses of photosensitizers are fairly high, that leads to unfavorable effects (toxicoses, lesions of normal skin, prolonged rehabilitation). This drawback can be overcome is photoimmunotoxins are used, i.e. conjugates of photosensitizers with antibodies to specific tumor markers. We tried to introduce a simple model for estimation of singlet oxygen effect on cells for the case of free photosensitizers, presented in outside solution, and in case of conjugated dye, bound by cell surface receptors. To achieve the same effect the required concentration of conjugated photosensitizer can be significantly decreased (50 to 100 fold) as compared with free dye. Methods for porphyrins and different phthalocyanines and naphthalocyanines conjugation with protein were developed. The use of bacteriophage T4 as a model for studying the action of photoimmunotoxines on virus, unambiguously demonstrated the applicability of this approach for targeted destruction of viral particles.

  7. Water soluble {2-[3-(diethylamino)phenoxy]ethoxy} substituted zinc(II) phthalocyanine photosensitizers

    Energy Technology Data Exchange (ETDEWEB)

    Çakır, Dilek [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Göl, Cem [Gebze Institute of Technology, Department of Chemistry, PO Box 141, Gebze, 41400, Kocaeli (Turkey); Çakır, Volkan [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Durmuş, Mahmut [Gebze Institute of Technology, Department of Chemistry, PO Box 141, Gebze, 41400, Kocaeli (Turkey); Bıyıklıoğlu, Zekeriya, E-mail: zekeriya_61@yahoo.com [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Kantekin, Halit [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey)

    2015-03-15

    The new peripherally and non-peripherally tetra-{2-[3-(diethylamino)phenoxy] ethoxy} substituted zinc phthalocyanines (2a and 3a) were synthesized by cyclotetramerization of phthalonitrile derivatives (2 and 3). 2-[3-(diethylamino)phenoxy] ethoxy group was chosen as substituent because the quaternization of the diethylamino functionality on the structure of this group produced water soluble zinc phthalocyanines (2b and 3b). The water solubility is very important for many different applications such as photosensitizers in the photodynamic therapy of cancer because the water soluble photosensitizers can be injected directly to the body and they can transport to cancer cells through blood stream. The new compounds were characterized by using elemental analysis, UV–vis, IR, {sup 1}H NMR, {sup 13}C NMR and mass spectroscopies. The photophysical and photochemical properties of these novel photosensitizer compounds were examined in DMSO (both non-ionic and ionic complexes) and in PBS (for ionic complexes) solutions. The investigation of these properties is very important for the usage of the compounds as photosensitizers for PDT because determination of these properties is the first stage of potential of the compounds as photosensitizers. The bovine serum albumin (BSA) and DNA binding behaviour of the studied water soluble zinc (II) phthalocyanines were also investigated in PBS solutions for the determination of biological activity of these compounds. - Highlights: • Synthesis of water soluble zinc phthalocyanines. • Photophysical and photochemical properties for phthalocyanines. • Photodynamic therapy studies.

  8. Photosensitive Gaseous Detectors for Cryogenic Temperature Applications

    CERN Document Server

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

    2007-01-01

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

  9. Photophysical and photosensitizing properties of selected cyanines.

    Science.gov (United States)

    Kassab, Kawser

    2002-08-01

    The present work has been carried out to obtain detailed information about the photophysical and photobiological properties of selected cyanines, in view of their possible use as photosensitizing agents. All the cyanines studied by us except CY-IV (3,3'-diethyl-4,4'-oxacarbocyanine), expressed an accelerated photobleaching in aqueous medium, a poor generation of singlet oxygen, and a relative weak photosensitizing activity towards albumin. On the cellular level, all cyanines exhibited a significant phototoxicity towards Balb/c 3T3 cells, upon irradiation with a total fluence of 30 J/cm(2). CY-III (3,3'-diethylcarbothiocayanine iodide) and CY-II (1,1'-diethyl-4,4'-carbocyanine iodide) appear to be promising photosensitizers, in spite of previous reports on the inefficiency of the former cyanine, and the rapid photobleaching of the latter compound.

  10. Novel visible light activated type 1 photosensitizers

    Science.gov (United States)

    Rajagopalan, Raghavan; Karwa, Amolkumar; Poreddy, Amruta R.; Lusiak, Przemyslaw M.; Pandurangi, Raghoottama S.; Cantrell, Gary L.; Dorshow, Richard B.

    2010-02-01

    Photodynamic therapy of tumors involving Type 2 photosenstizers has been conspicuously successful, but the Type 1 process, in contrast, has not received much attention despite its considerable potential. Accordingly, several classes of molecules containing fragile bonds such as azido (-N=N=N), azo (-N=N-), and oxaza (-N-O-) functional groups that produce reactive intermediates such as radicals and nitrenes upon photoexcitation with visible light were prepared and tested for cell viability using U397 leukemia cell line. The cells were incubated with the photosensitizer at various concentrations, and were illuminated for 5, 10, and 20 minutes. The results show that all the photosensitizers caused cell death compared to the controls when exposed to both the photosensitizers and light.

  11. Persistent photosensitivity caused by musk ambrette.

    Science.gov (United States)

    Zugerman, C

    1981-07-01

    Persistent photosensitivity developed in a man after use of an after-shave lotion containing musk ambrette. His eruption, present over ligh-exposed areas of the face, the "V" area of the neck, and the dorsa of the hands, has persisted for more than three years despite therapy. The patient demonstrated a minimal erythema after an ultraviolet B dose of 5 s, and was strongly ultraviolet A photosensitive to a 2% musk ambrette solution in petrolatum and to the after-shave lotion that contained musk ambrette. A persistent light reactivity induced by musk ambrette has most likely developed in this patient.

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

    Science.gov (United States)

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

    2016-03-22

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

  13. Substrate affinity of photosensitizers derived from chlorophyll-a: the ABCG2 transporter affects the phototoxic response of side population stem cell-like cancer cells to photodynamic therapy.

    Science.gov (United States)

    Morgan, Janet; Jackson, Jennifer D; Zheng, Xiang; Pandey, Suresh K; Pandey, Ravindra K

    2010-10-04

    Photosensitizers (PS) synthesized with the aim of optimizing photodynamic therapy (PDT) of tumors do not always fulfill their potential when tested in vitro and in vivo in different tumor models. The ATP-dependent transporter ABCG2, a multidrug resistant pump expressed at variable levels in cancerous cells, can bind and efflux a wide range of structurally different classes of compounds including several PS used preclinically and clinically such as porphyrins and chlorins. ABCG2 may lower intracellular levels of substrate PS below the threshold for cell death in tumors treated by PDT, leaving resistant cells to repopulate the tumor. To determine some of the structural factors that affect substrate affinity of PS for ABCG2, we used an ABCG2-expressing cell line (HEK 293 482R) and its nonexpressing counterpart, and tyrosine kinase ABCG2 inhibitors in a simple flow cytometric assay to identify PS effluxed by the ABCG2 pump. We tested a series of conjugates of substrate PS with different groups attached at different positions on the tetrapyrrole macrocycle to examine whether a change in affinity for the pump occurred and whether such changes depended on the position or the structure/type of the attached group. PS without substitutions including pyropheophorbides and purpurinimides were generally substrates for ABCG2, but carbohydrate groups conjugated at positions 8, 12, 13, and 17 but not at position 3 abrogated ABCG2 affinity regardless of structure or linking moiety. At position 3, affinity was retained with the addition of iodobenzene, alkyl chains and monosaccharides, but not with disaccharides. This suggests that structural characteristics at position 3 may offer important contributions to requirements for binding to ABCG2. We examined several tumor cell lines for ABCG2 activity, and found that although some cell lines had negligible ABCG2 activity in bulk, they contained a small ABCG2-expressing side population (SP) thought to contain cells which are responsible

  14. The Factors Affecting Optical Anisotropy of the Film Derived from a Liquid Crystal Polymer with Photosensitive Groups%影响液晶高分子光学各向异性的因素

    Institute of Scientific and Technical Information of China (English)

    杨姣; 张伟民; 曹进; 蒲嘉陵

    2014-01-01

    以4-(6-丙烯酰氧基己氧基)苯甲酸-4-羟基-4-(甲氧基)酯和4-(6-丙烯酰氧基己氧基)苯甲酸-7-羟基香豆素酯为单体合成了一种共聚物,并研究了影响此液晶高分子光学各向异性的因素。通过动态紫外光谱考查了曝光量、曝光温度及热处理温度对液晶聚合物膜层光化学性能及取向性能的影响。结果表明:随着曝光量的增加,聚合物薄膜光化学反应程度逐渐增大,且在曝光量为3.7J/cm2时,光化学反应程度达到饱和。随着曝光温度的增加,分子发生了光重排反应,而光二聚反应程度降低。在曝光量为3.7J/cm2及曝光温度25℃时,聚合物薄膜随着热处理温度的升高,液晶分子的取向方向呈现一定的周期变化,但产生的最大各向异性值基本保持不变。%In this paper, a liquid crystal copolymer was prepared by 4-( 6-acryloyloxy-hexyloxy ) benzoic acid-4-hydroxyl-4-( methoxyl ) ester and 4-( 6-acryloyloxy-hexyloxy ) benzoic acid-7-hydroxyl, and it was used to study the factors which affected optical anisotropy of liquid crystal polymer with photosensitive groups. The photoreaction behaviors and orientation performance of the liquid crystal polymer film were investigated with linearly polarized ultraviolet light ( LPUV ) under different exposure dose, exposure temperature and annealing temperature. The results showed that the degree of photoreaction of the film was enhanced with increasing of exposure energy. When the exposure energy reached 3. 7J/cm2 , the maximum degree of photoreaction was achieved. Under higher exposure temperatures, the Photo-Fries rearrangement occurred, whereas the photo - induced dimerization reaction was reduced. At last, under the room temperature and exposure dose of 3. 7J/cm2 , the optical anisotropy of the liquid crystal film exhibited periodic variation as the annealing temperature was rising. However, the maximum anisotropy value remained nearly unchanged.

  15. Severe photosensitivity reaction induced by topical diclofenac

    OpenAIRE

    Akat, Pramod B.

    2013-01-01

    Albeit uncommon, photosensitivity reaction induced by diclofenac can be an unfortunate adverse reaction complicating its use as a topical analgesic. We here present a case of a patient who suffered such a reaction as a result of exposure to diclofenac, employed as a topical analgesic for low backache. The lesions healed with conservative management without extensive scarring or other complications.

  16. Severe photosensitivity reaction induced by topical diclofenac

    Directory of Open Access Journals (Sweden)

    Pramod B Akat

    2013-01-01

    Full Text Available Albeit uncommon, photosensitivity reaction induced by diclofenac can be an unfortunate adverse reaction complicating its use as a topical analgesic. We here present a case of a patient who suffered such a reaction as a result of exposure to diclofenac, employed as a topical analgesic for low backache. The lesions healed with conservative management without extensive scarring or other complications.

  17. Photosensitivity of layered semiconductor propolis heterocontact

    Science.gov (United States)

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

    2003-03-01

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

  18. Trichothiodystrophy: Photosensitive, TTD-P, TTD, Tay syndrome.

    Science.gov (United States)

    Lambert, W Clark; Gagna, Claude E; Lambert, Muriel W

    2010-01-01

    Although the term, "trichothiodystrophy" (TTD) refers to the hair anomalies in this group of patients, this is a heterogeneous, multisystem disease in which any or every organ in the body may be affected. Neuroectodermal derived tissues are particularly likely to be involved. This term was introduced by Price et alin 1980 to designate patients with sulfur-deficient brittle hair, which they recognized as a marker for this complex disease and designated it as a "neuroectodermal symptom complex". Patients with TTD have brittle hair and nails (associated with reduced content ofcysteine-rich matrix proteins), ichthyotic skin and physical and mental growth retardation. Ichthyosis is usually apparent at birth but much less so after the first few weeks of life. Other frequently associated features include ocular cataracts, infections and maternal complications related to pregnancy. Atrophy of subcutaneous fat may also be present. TTD occurs in a pattern of inheritance consistent with an autosomal recessive condition. The disease is extremely heterogeneous in severity and extent, with some patients showing no neurological deficiency. Others show severe, multisystem disease. Many patients die at a young age, most commonly due to infectious disease. TTD is part of a more broadly defined group of diseases identified as IBIDS (ichthyosis, brittle hair, impaired intelligence, decreased fertility and short stature). Photosensitive cases are also identified as PIBIDS (photosensitivity with IBIDS). Cases without manifest ichthyosis are also identified as PBIDS. These syndromes defy rigorous definition because of clinical variation between patients. The original two cases were described by Tay in oriental siblings, whose parents were first cousins; thus the disease is also known as Tay syndrome. The hairs in patients with TTD have a distinctive, diagnostically useful appearance on polarized light microscopy consisting of alternating light and dark bands known as the "tiger tail

  19. Photosensitizers from Spirulina for Solar Cell

    OpenAIRE

    Liqiu Wang; Liang Tian; Xinxin Deng; Mengyi Zhang; Shuping Sun; Wei Zhang; Lin Zhao

    2014-01-01

    Spirulina is a kind of blue-green algae with good photosynthetic efficiency and might be used for photovoltaic power generation. So this paper used living spirulina as novel photosensitizer to construct spirulina biosolar cell. The results showed that spirulina had the photoelectric conversion effect, and could let the spirulina biosolar cell have 70 μA photocurrent. Meanwhile, adding glucose sucrose or chitosan in the spirulina anode chamber, they could make the maxima current density of the...

  20. Photosensitive surfactants: micellization and interaction with DNA.

    Science.gov (United States)

    Zakrevskyy, Yuriy; Roxlau, Julian; Brezesinski, Gerald; Lomadze, Nino; Santer, Svetlana

    2014-01-28

    Recently, photosensitive surfactants have re-attracted considerable attention. It has been shown that their association with oppositely charged biologically important polyelectrolytes, such as DNA or microgels, can be efficiently manipulated simply by light exposure. In this article, we investigate the self-assembly of photosensitive surfactants as well as their interactions with DNA by calorimetric and spectroscopic methods. Critical micelle concentration (CMC), standard micellization enthalpy, entropy, and Gibbs energy were determined in different conditions (ionic strengths and temperatures) for a series of cationic surfactants with an azobenzene group in their tail. It is shown, that aggregation forces of photosensitive units play an important role in the micellization giving the major contribution to the micellization enthalpy. The onset of the aggregation can be traced from shift of the absorption peak position in the UV-visible spectrum. Titration UV-visible spectroscopy is used as an alternative, simple, and sensitive approach to estimate CMC. The titration UV-visible spectroscopy was also employed to investigate interactions (CAC: critical aggregation concentration, precipitation, and colloidal stabilization) in the DNA-surfactant complex.

  1. Photosensitive surfactants: Micellization and interaction with DNA

    Science.gov (United States)

    Zakrevskyy, Yuriy; Roxlau, Julian; Brezesinski, Gerald; Lomadze, Nino; Santer, Svetlana

    2014-01-01

    Recently, photosensitive surfactants have re-attracted considerable attention. It has been shown that their association with oppositely charged biologically important polyelectrolytes, such as DNA or microgels, can be efficiently manipulated simply by light exposure. In this article, we investigate the self-assembly of photosensitive surfactants as well as their interactions with DNA by calorimetric and spectroscopic methods. Critical micelle concentration (CMC), standard micellization enthalpy, entropy, and Gibbs energy were determined in different conditions (ionic strengths and temperatures) for a series of cationic surfactants with an azobenzene group in their tail. It is shown, that aggregation forces of photosensitive units play an important role in the micellization giving the major contribution to the micellization enthalpy. The onset of the aggregation can be traced from shift of the absorption peak position in the UV-visible spectrum. Titration UV-visible spectroscopy is used as an alternative, simple, and sensitive approach to estimate CMC. The titration UV-visible spectroscopy was also employed to investigate interactions (CAC: critical aggregation concentration, precipitation, and colloidal stabilization) in the DNA-surfactant complex.

  2. The depth of porphyrin in a membrane and the membrane's physical properties affect the photosensitizing efficiency.

    Science.gov (United States)

    Lavi, Adina; Weitman, Hana; Holmes, Robert T; Smith, Kevin M; Ehrenberg, Benjamin

    2002-01-01

    Photosensitized biological processes, as applied in photodynamic therapy, are based on light-triggered generation of molecular singlet oxygen by a membrane-residing sensitizer. Most of the sensitizers currently used are hydrophobic or amphiphilic porphyrins and their analogs. The possible activity of the short-lived singlet oxygen is limited to the time it is diffusing in the membrane, before it emerges into the aqueous environment. In this paper we demonstrate the enhancement of the photosensitization process that is obtained by newly synthesized protoporphyrin derivatives, which insert their tetrapyrrole chromophore deeper into the lipid bilayer of liposomes. The insertion was measured by fluorescence quenching by iodide and the photosensitization efficiency was measured with 9,10-dimethylanthracene, a fluorescent chemical target for singlet oxygen. We also show that when the bilayer undergoes a melting phase transition, or when it is fluidized by benzyl alcohol, the sensitization efficiency decreases because of the enhanced diffusion of singlet oxygen. The addition of cholesterol or of dimyristoyl phosphatydilcholine to the bilayer moves the porphyrin deeper into the bilayer; however, the ensuing effect on the sensitization efficiency is different in these two cases. These results could possibly define an additional criterion for the choice and design of hydrophobic, membrane-bound photosensitizers. PMID:11916866

  3. Photosensitivity in feedlot calves apparently related to cocoa shells.

    Science.gov (United States)

    Yeruham, I; Avidar, Y; Perl, S

    2003-10-01

    Primary photosensitization was observed in 11/78 cross-breed calves. The skin lesions were diffuse dermatitis with thickening and wrinkling with areas of alopecia. The severe photosensitivity dermatitis was associated with cocoa shell ingestion. The lesions resolved after removal of the cocoa shells from the feed ration and prevention of exposure to sunlight. Cocoa shells may contain photodynamic agents that cause photosensitization in calves.

  4. Headache, epilepsy and photosensitivity: how are they connected?

    National Research Council Canada - National Science Library

    Kasteleijn-Nolst Trenité, Dorothée G. A; Verrotti, Alberto; Di Fonzo, Alessia; Cantonetti, Laura; Bruschi, Raffaella; Chiarelli, Francesco; Villa, Maria Pia; Parisi, Pasquale

    2010-01-01

    Although headache and epilepsy have often been associated, the precise electroclinical and pathophysiological interaction between these disorders and in particular its relations with photosensitivity...

  5. A novel in vitro method for the detection and characterization of photosensitizers.

    Directory of Open Access Journals (Sweden)

    Nadine Karschuk

    Full Text Available Photoactivation and binding of photoactive chemicals to proteins is a known prerequisite for the formation of immunogenic photoantigens and the induction of photoallergy. The intensive use of products and the availability of new chemicals, along with an increasing exposure to sun light contribute to the risk of photosensitizing adverse reactions. Dendritic cells (DC play a pivotal role in the induction of allergic contact dermatitis. Human peripheral blood monocyte derived dendritic cells (PBMDC were thus perceived as an obvious choice for the development of a novel in vitro photosensitization assay using the modulation of cell surface protein expression in response to photosensitizing agents. In this new protocol, known chemicals with photosensitizing, allergenic or non-allergenic potential were pre-incubated with PBMDCs prior to UVA irradiation (1 J/cm(2. Following a 48 h incubation, the expression of the cell surface molecules CD86, HLA-DR and CD83 was measured by flow cytometry. All tested photosensitizers induced a significant and dose-dependent increase of CD86 expression after irradiation compared to non-irradiated controls. Moreover, the phototoxicity of the chemicals could also be determined. In contrast, (i CD86 expression was not affected by the chosen irradiation conditions, (ii increased CD86 expression induced by allergens was independent of irradiation and (iii no PBMDC activation was observed with the non-allergenic control. The assay proposed here for the evaluation of the photoallergenic potential of chemicals includes the assessment of their allergenic, phototoxic and toxic potential in a single and robust test system and is filling a gap in the in vitro photoallergenicity test battery.

  6. 78 FR 18999 - Prospective Grant of Start-Up Exclusive License: Photosensitizing Antibody-Fluorophore Conjugates...

    Science.gov (United States)

    2013-03-28

    ...: Photosensitizing Antibody-Fluorophore Conjugates for Photoimmunotherapy AGENCY: National Institutes of Health...-01), and entitled ``Photosensitizing Antibody- Fluorophore Conjugates,'' to Aspyrian Therapeutics.... The field of use may be limited to ``use of photosensitizing antibody-fluorophore conjugate by...

  7. New photosensitive systems for volume phase holography

    Science.gov (United States)

    Bianco, Andrea; Colella, Letizia; Galli, Paola; Zanutta, Alessio; Bertarelli, Chiara

    2017-05-01

    Volume phase holographic elements are becoming attractive thanks to the large efficiency and good optical quality. They are based on photosensitive materials where a modulation of the refractive index is induced. In this paper, we highlight the strategies to obtain a change in the refractive index in a dielectric material, namely a change in the material density and/or in the molecular polarizability. Moreover, we show the results achieved for materials that undergo the photo-Fries reaction as function of the molecular structure and the illumination conditions. We also report the results on a system based on the diazo Meldrum's acid where volatile molecules are produced upon light exposure.

  8. Semiconductor nanocrystals photosensitize C60 crystals.

    Science.gov (United States)

    Biebersdorf, Andreas; Dietmüller, Roland; Susha, Andrei S; Rogach, Andrey L; Poznyak, Sergey K; Talapin, Dmitri V; Weller, Horst; Klar, Thomas A; Feldmann, Jochen

    2006-07-01

    Semiconductor nanocrystals (SCNCs) made of CdSe, CdTe, and InP are used to photosensitize needlelike C(60) crystals. The photocurrent is increased by up to 3 orders of magnitude as compared with C(60) crystals without SCNCs. The photocurrent spectrum can be tuned precisely by the SCNC size and material, rendering the SCNC-functionalized C(60) crystals an excellent material for spectrally tuneable photodetectors. We explain the increased photocurrent as a result of photoexcited electrons transferring from the SCNCs to the C(60) crystals and causing photoconductivity, while the complementary holes remain trapped in the SCNCs.

  9. Phototherapeutic, photobiologic, and photosensitizing properties of khellin

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-05-01

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

  10. The correlation between photosensitizers' membrane localization, membrane-residing targets, and photosensitization efficiency

    Science.gov (United States)

    Ytzhak, Shany; Bernstein, Shoshana; Loew, Leslie M.; Ehrenberg, Benjamin

    2009-06-01

    Various tetrapyrroles act as photosensitizers by efficiently generating singlet oxygen. Hydrophobic or amphiphilic photosensitizers are taken up by cells and are usually located in various cellular lipid membranes. Passive uptake by a membrane depends on biophysical properties of the membrane, such as its composition, temperature, phase, fluidity, electric potential etc., as well as on the external solution's properties. Although the intrinsic lifetime of singlet oxygen in the membrane phase is 10-30 μs, depending on lipid composition, it escapes much faster out of the membrane into the external or internal aqueous medium, where its lifetime is <3 μs. Any damage that singlet oxygen might inflict to membrane constituents, i.e. proteins or lipids, must thus occur while it is diffusing in the membrane. As a result, photosensitization efficiency depends, among others, on the location of the sensitizer in the membrane. Singlet oxygen can cause oxidative damage to two classes of targets in the membrane: lipids and proteins. Depolarization of the Nernst electric potential on cells' membranes was observed, but it is not clear whether lipid oxidation is a relevant factor leading to abolishing the resting potential of cells' membranes and to their death. We present a study of the effect of membrane lipid composition and the dissipation of the electric potential that is generated across the membrane. We find a clear correlation between the structure and unsaturation of lipids and the leakage of the membrane, which can be caused by their photosensitized oxidization. We demonstrate here that when liposomes are composed of mixtures similar to natural membranes, and photosensitization is being carried out under usual PDT conditions, photodamage to the lipids is not likely to cause enhanced permeability of ions through the membrane, which could be a mechanism that leads to cell death.

  11. Nanobody-photosensitizer conjugates for targeted photodynamic therapy

    NARCIS (Netherlands)

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

    2014-01-01

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

  12. Investigation of the photosensitivity, temperature sustainability and fluorescence characteristics of several Er-doped photosensitive fibers

    CERN Document Server

    Shen, Y H; Mandal, J; Sun, T; Grattan, K T V; Wade, S A; Collins, Stephen F; Baxter, Gregory W; Dussardier, Bernard; Monnom, Gérard

    2011-01-01

    Three different types of Er doped photosensitive fibers, germanium/erbium (Ge/Er) fiber, tin/germanium/erbium fiber (Sn/Er) and antimony/germanium/erbium fiber (Sb/Er) have been manufactured and studied for use in optical sensor systems. Their characteristics of photosensitivity, the temperature sustainability of fiber Bragg gratings (FBGs) written into these fibers and the fluorescence emission from the Er dopant were investigated and compared. It has been shown in this work that these fibers all show a satisfactory degree of photosensitivity to enable the fabrication of FBGs and a significant level of fluorescence emission within the 1550 nm band for sensor use. The high temperature sustainability of the FBGs written into these fibers was investigated and seen to be quite significant at temperatures as high as 850 ^{\\circ}C, in particular for the Sn/Er and Sb/Er fibers. A fiber laser using the Sb/Er fiber as the gain medium was demonstrated, giving evidence of the strong fluorescence emission from the Er do...

  13. In vitro lethal photosensitization of S. mutans using methylene blue and toluidine blue O as photosensitizers.

    Science.gov (United States)

    Araújo, Patrícia V; Teixeira, Karina I R; Lanza, Lincoln D; Cortes, Maria E; Poletto, Luiz T A

    2009-01-01

    The purpose of this in vitro study was to evaluate the antimicrobial effect of photodynamic therapy on Streptococcus mutans (A TCC 25175) suspensions, using a red laser for one minute in combination with toluidine blue O (TBO) or methylene blue (MB). Both photosensitizers were used in three concentrations (25, 10 and 5 mg/L). The activity ofphotosensitizers and laser irradiation were tested separately on the bacteria, as well as the irradiation of this light source in the presence of the TBO or MB. These groups were compared to a control group, in which the microorganism did not receive any treatment. The activity of both TBO and MB or laser irradiation, alone, were not able to reduce the number of S. mutans. In the groups of lethal photosensitization, a bacterial reduction of 70% for TBO and 73% for MB was observed when these photosensitizers were used at 25 mg/L and a reduction of 48% was observed for MB at 5mg/L. In other concentrations there were no significant differences in comparison to the control group. Both the TBO and the MB at 25 mg/L associated with a red laser had an excellent potential for use in PDT in lethal sensitization of S. mutans.

  14. Photosensitizers mediated photodynamic inactivation against virus particles.

    Science.gov (United States)

    Sobotta, Lukasz; Skupin-Mrugalska, Paulina; Mielcarek, Jadwiga; Goslinski, Tomasz; Balzarini, Jan

    2015-01-01

    Viruses cause many diseases in humans from the rather innocent common cold to more serious or chronic, life-threatening infections. The long-term side effects, sometimes low effectiveness of standard pharmacotherapy and the emergence of drug resistance require a search for new alternative or complementary antiviral therapeutic approaches. One new approach to inactivate microorganisms is photodynamic antimicrobial chemotherapy (PACT). PACT has evolved as a potential method to inactivate viruses. The great challenge for PACT is to develop a methodology enabling the effective inactivation of viruses while leaving the host cells as untouched as possible. This review aims to provide some main directions of antiviral PACT, taking into account different photosensitizers, which have been widely investigated as potential antiviral agents. In addition, several aspects concerning PACT as a tool to assure viral inactivation in human blood products will be addressed.

  15. Lethal photosensitization of biofilm-grown bacteria

    Science.gov (United States)

    Wilson, Michael

    1997-12-01

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

  16. Photosensitizer quantitation in vivo by flourescence microsampling

    Science.gov (United States)

    Pogue, Brian W.; Burke, Gregory C.; Lee, Claudia C.; Hoopes, P. Jack

    2000-06-01

    Photodynamic therapy can provide a reliable method of tumor destruction when the appropriate dosimetry is applied. Current dosimetry practice involves quantification of the drug and light doses applied to the tumor, but it would be desirable to monitor in vivo light and drug levels to provide the most accurate determination of dosimetry. In vivo measurements can be used to minimize variations in treatment response due to inter-animal variability, by providing animal-specific or patient-specific treatment planning. This study reports on the development of a micro-sampling method to measure fluorescence from tissue, which is not significantly affected by the tissue optical properties. The system measures fluorescence from the surface of a tissue, using a fiber bundle composed of individual 100 micron fibers which ar all spaced apart by 700 microns from one another at the tissue contact end. This design provides sampling of the fluorescence at multiple sites to increase the signal intensity, while maintaining a micro- sampling of the tissue volume just below the surface. The calibration studies here indicate that the 1/e sampling depth is near 60 microns when measured in optical phantoms, which are similar to typical tissue properties. The probe fluorescence signal is independent of blood concentration up to a maximum of 10% blood by volume, which is similar to most tumor tissue. Animal tests indicate that the sensitivity to drug concentration is essentially the same in when measured in murine liver and muscle tissues, both in vivo and ex vivo. These preliminary calibration results suggest that the probe can be used to measure photosensitizer uptake in vivo non- invasively and rapidly via conversion of fluorescence intensity to photosensitizer concentration.

  17. Sonodynamic therapy with photosensitizers and its combination with photodynamic therapy in treatment of malignant tumors

    Directory of Open Access Journals (Sweden)

    D. A. Zerkovskiy

    2014-01-01

    Full Text Available The article reviews mechanisms of sonodynamic therapy with photosensitizers (ultrasound + photosensitizer and combination of sonodynamic with photodynamic therapy (ultrasound + photosensitizer + light exposure for treatment of malignant tumors. Efficacy of these methods with photosensitizers of different chemical structure in experimental study in vitro and in vivo on different tumor models and in clinical trials was assessed. 

  18. Relationship among eye condition sensitivities,photosensitivity and epileptic syndromes

    Institute of Scientific and Technical Information of China (English)

    YANG Zhi-xian; CAI Xiang; LIU Xiao-yan; QIN Jiong

    2008-01-01

    Background Electroencephalogram(EEG)activity in normal subjects and epileptic patients is often closely related to the eye's status such as eye opened(EO),eye closure(ECL)and eyes closed(EC).ECL is the period immediately after closing of the eyes and only Iasts for Jess than 3 seconds if the eyes remain closed.EC is the pened as long as the eyes are closed.Epileptiform changes on EEG induced by ECL or EC are called the changes of ECL sensitivity(ECLS)or EC sensitivity (ECS).ECLS occurs mainly but not exclusively in photosensitive patients and ECS has been seen rarely in photosensitive patients.This study aimed to investigate the relationships among ECLS,ECS.photosensitivity and epilepsy syndromes in children.Methods EEG records from child patients in the EEG Department of Peking University First Hospital dudng the period of May 2005 to Mav 2007 were examined for the presence of ECLS or ECS.Open-close eye tests and intermittent photic stimulations were carried out during video-EEG monitoring for examining ECLS.ECS and photosensitivity.Results Based on ECLS and ECS on their EEGs,30 patients were divided into ECLS group (16 cases)and ECS group (14 cases).There were more boys than girls in the two groups.The mean age of initial detection of ECLS and ECS was 10 years.and the average onset age of seizures was 9 years.The epilepsy syndromes in the ECLS group included idiopathic photosensitive occipital lobe epilepsy,Panayiotopoulos syndrome,symptomatic occipital lobe epilepsy,juvenile myoclonic epilepsy,juvenile absence epilepsy,eyelid myoclonia with absences,epilepsy with grand mal on awakening and pure photosensitive epilepsy with mainly generalized tonic clonic seizures.Those in the ECS group were iuvenile myoclonic epilepsy,idiopathic photosensitive occipital Iobe epilepsy,Panayiotopoulos syndrome and Gastaut type-idiclpathic children occipital epilepsy.Photosensitivity was detected in 88%of Patients with ECLS and 29%of patients with ECS.Conclusions ECLS and ECS are

  19. Pesticide photolysis in prairie potholes: probing photosensitized processes.

    Science.gov (United States)

    Zeng, Teng; Arnold, William A

    2013-07-02

    Prairie pothole lakes (PPLs) are glacially derived, ecologically important water bodies found in central North America and represent a unique setting in which extensive agriculture occurs within wetland ecosystems. In the Prairie Pothole Region (PPR), elevated pesticide use and increasing hydrologic connectivity have raised concerns about the impact of nonpoint source agricultural pollution on the water quality of PPLs and downstream aquatic systems. Despite containing high dissolved organic matter (DOM) levels, the photoreactivity of the PPL water and the photochemical fate of pesticides entering PPLs are largely unknown. In this study, the photodegradation of sixteen pesticides was investigated in PPL waters sampled from North Dakota, under simulated and natural sunlight. Enhanced pesticide removal rates in the irradiated PPL water relative to the control buffer pointed to the importance of indirect photolysis pathways involving photochemically produced reactive intermediates (PPRIs). The steady-state concentrations of carbonate radical, hydroxyl radical, singlet oxygen, and triplet-excited state DOM were measured and second-order rate constants for reactions of pesticides with these PPRIs were calculated. Results from this study underscore the role of DOM as photosensitizer in limiting the persistence of pesticides in prairie wetlands through photochemical reactions.

  20. The molecular basis for the high photosensitivity of rhodopsin.

    Science.gov (United States)

    Liu, Robert S H; Colmenares, Leticia U

    2003-12-09

    Based on structural information derived from the F NMR data of labeled rhodopsins, rhodopsin crystal structure, and excited-state properties of model polyenes, we propose a molecular mechanism that accounts specifically for the causes of the well-known enhanced photoreactivity of rhodopsin (increased rates and quantum yield of isomerization). It involves the key features of close proximity of C-187 to H-12 and chromophore bond lengthening upon light absorption. The resultant "sudden punch" to H-12 triggers dual processes of decay of the Franck-Condon-excited rhodopsin, a productive directed photoisomerization and a nonproductive decay returning to the ground state as two separate molecular pathways [based on real-time fluorescence results of Chosrowjan, H., Mataga, N., Shibata, Y., Tachibanaki, S., Kandori, H., Shichida, Y., Okada, T. & Kouyama, T. (1998) J. Am. Chem. Soc. 120, 9706-9707]. The two processes are controlled by the local protein structure: an empty space provided by the intradiscal loop connecting transmembrane helices 4 and 5 and a protein wall composed of amino acid units in transmembrane 3. Suggestions, involving retinal analogs and rhodopsin mutants, to improve the unusually high photosensitivity of rhodopsin are proposed.

  1. A Photosensitive Copolymer for UV-curable Eleetrodeposition Coatings

    Institute of Scientific and Technical Information of China (English)

    LIU Ren; LI Xiaojie; AN Fenglci; ZHANG Shengwen; LIU Xiaoya

    2011-01-01

    A series of photosensitive random copolymers (UPDHES) were prepared by introducing acrylate groups onto the side chain of the copolymer backbone of N,N-domethyl amimethyl methacrylate (DMAEMA),2-hydroxypropyl acrylate (HEA),2-ethylhexyl acrylate (EHA),and styrene (St) (PDHES).The molecular structure of UPDHES was characterized by FTIR,1HNMR and GPC.The photopolymerization kinetics of UPDHES with different C=C content was investigated using real time FTIR in which it was found that the UPDHES system had notable photosensitivity.The effect of C=C content on the properties of cured films were studied by evaluating various film properties such as thermal stability,glass transition temperature and tensile properties.The thermal degradation of cured films was investigated via thermogravimetric analysis/infrared spectrometry (TGA-IR).Thus a series of UV-curable electrodeposition coatings with good photosensitivity and mechanical properties were prepared from a low-cost photosensitive random copolymer.

  2. Modified developer increases line resolution in photosensitive resist

    Science.gov (United States)

    1965-01-01

    Standard developer solution is mixed with dipropyl carbonate. This reduces swelling in the photosensitive resist and permits application of relatively thick films with minimal pinhole formation and increased line resolution.

  3. Photosensitizing medication use and risk of skin cancer

    DEFF Research Database (Denmark)

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

    2010-01-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

  5. Photosensitizing Nanoparticles and The Modulation of Reactive Oxygen Species generation

    Directory of Open Access Journals (Sweden)

    Dayane Batista Tada

    2015-05-01

    Full Text Available The association of PhotoSensitizer (PS molecules with nanoparticles (NPs forming photosensitizing NPs, has emerged as a therapeutic strategy to improve PS tumor targeting, to protect PS from deactivation reactions and to enhance both PS solubility and circulation time. Since association with NPs usually alters PS photophysical and photochemical properties, photosensitizing NPs are an important tool to modulate reactive oxygen species (ROS generation. Depending on the design of the photosensitizing NP, i.e., type of PS, the NP material and the method applied for the construction of the photosensitizing NP, the deactivation routes of the excited state can be controlled, allowing the generation of either singlet oxygen or other ROS. Controlling the type of generated ROS is desirable not only in biomedical applications, as in Photodynamic Therapy where the type of ROS affects therapeutic efficiency, but also in other technological relevant fields like energy conversion, where the electron and energy transfer processes are necessary to increase the efficiency of photoconversion cells. The current review highlights some of the recent developments in the design of Photosensitizing NPs aimed at modulating the primary photochemical events after light absorption.

  6. Photosensitizing Nanoparticles and The Modulation of Reactive Oxygen Species generation

    Science.gov (United States)

    Tada, Dayane; Baptista, Mauricio

    2015-05-01

    The association of PhotoSensitizer (PS) molecules with nanoparticles (NPs) forming photosensitizing NPs, has emerged as a therapeutic strategy to improve PS tumor targeting, to protect PS from deactivation reactions and to enhance both PS solubility and circulation time. Since association with NPs usually alters PS photophysical and photochemical properties, photosensitizing NPs are an important tool to modulate reactive oxygen species (ROS) generation. Depending on the design of the photosensitizing NP, i.e., type of PS, the NP material and the method applied for the construction of the photosensitizing NP, the deactivation routes of the excited state can be controlled, allowing the generation of either singlet oxygen or other ROS. Controlling the type of generated ROS is desirable not only in biomedical applications, as in Photodynamic Therapy where the type of ROS affects therapeutic efficiency, but also in other technological relevant fields like energy conversion, where the electron and energy transfer processes are necessary to increase the efficiency of photoconversion cells. The current review highlights some of the recent developments in the design of Photosensitizing NPs aimed at modulating the primary photochemical events after light absorption.

  7. Suppression of Cladding Mode Coupling by B/Ge Codoped Photosensitive Fiber With Photosensitive and Depressed Inner Cladding

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Excess loss on the short wavelength side of the Bragg resonant wavelength caused by cladding mode coupling limits wide use of grating in the fiber communication system, especially in densed wavelength division multiplexing (DWDM) system.A novel photosensitive fiber design that have depressed cladding and photosensitive inner cladding in the same fiber is proposed, which can suppress cladding mode coupling greatly.Using MCVD method B/Ge codoped fiber with depressed cladding was fabriceted out, which was also doped in boron and germanium and had the photosensitivity.Finally, the transmission spectrum of written grating in this fiber by phase mask method verified its larger photosensitivity and greatly suppression of cladding mode coupling.

  8. Homogeneous photosensitized degradation of pharmaceuticals by using red light LED as light source and methylene blue as photosensitizer

    NARCIS (Netherlands)

    Ye, Y.; Bruning, H.; Yntema, D.; Mayer, M.; Rijnaarts, H.

    2017-01-01

    Research on employing advanced oxidation processes (AOPs) for pharmaceuticals removal is gaining interests. However, detrimental effects of background water constituents in complex water matrices are limiting their implementation. In this study, we report red light induced methylene blue photosensit

  9. Influence of metronidazole and some electron acceptors on the chlorin e6 photosensitized killing of Ehrlich carcinoma cells

    Science.gov (United States)

    Chekulayev, V.; Shevchuk, Igor; Mihkelsoo, Virgo T.; Kallikorm, A. P.

    1992-06-01

    A decrease in the effectiveness of photosensitized killing of neoplasm cells was observed in the presence of chlorin-e6 at a reduced concentration of oxygen. But when metronidazole (MZ) was injected in vitro as well as in vivo, a significant increase in the photosensitized killing of Ehrlich carcinoma cells by chlorin-e6 was observed. Moreover, contrary to the hematoporphyrin derivative (HpD), MZ increases the effectiveness of photodynamic therapy (PDT) by using chlorin-e6 not only in the hypoxic but also in the aerobic conditions. The interaction between MZ and the excited photosensitizer may account for an increased phototoxicity of chlorin-e6. The formation of cytotoxic nitroimidazole radicals as a result of photochemical processes of type 1 is discussed. This property of the photosensitizer may be successfully used in working out a method of potentiating PDT in combination not only with nitroimidazoles, but also with other electron acceptor compounds (EACp), e.g., quinone antitumor antibiotics.

  10. Photosensitizers from Spirulina for Solar Cell

    Directory of Open Access Journals (Sweden)

    Liqiu Wang

    2014-01-01

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

  11. Seneciosis in cattle associated with photosensitization

    Directory of Open Access Journals (Sweden)

    Paula R. Giaretta

    2014-05-01

    Full Text Available Senecio spp. poisoning is the main cause of cattle mortality in the central region of Rio Grande do Sul. This paper reports an outbreak of seneciosis in cattle with high prevalence of photosensitization, where 83 out of 162 cows (51.3% presented this clinical sign. The outbreak occurred in September 2013, affecting adult cows that were held in a 205 hectare-pasture from April to October 2013 with abundant Senecio brasiliensis infestation. Main clinical signs were weight loss, excessive lacrimation or mucopurulent ocular discharge, nasal serous discharge, ventral diphteric glossitis, crusts in the nose, teats, dorsum of ears, and vulva. Liver biopsy was performed in all the cows under risk; the histopathological findings in the liver biopsies consisted of fibrosis, megalocytosis, and biliary ductal proliferation and were present in 73.4% of the biopsied animals. Six cows had increased serum activity of gamma glutamyl transferase. Three affected cows were necropsied. The main necropsy findings were a hard liver, distended gall bladder, edema of the mesentery and abomasum. Liver histological changes in the necropsied cows were similar to those of the biopsied livers. Spongiosis was detected in the brain of necropsied cows and is characteristic of hepatic encephalopathy.

  12. Chemically-enzymatic synthesis of photosensitive DNA.

    Science.gov (United States)

    Westphal, Kinga; Zdrowowicz, Magdalena; Zylicz-Stachula, Agnieszka; Rak, Janusz

    2017-02-01

    The sensitizing propensity of radio-/photosensitizing nucleoside depends on DNA sequence surrounding a sensitizer. Therefore, in order to compare sensitizers with regard to their ability to induce a DNA damage one has to study the sequence dependence of damage yield. However, chemical synthesis of oligonucleotides labeled with sensitizing nucleosides is hindered due to the fact that a limited number of such nucleoside phosphoramidites are accessible. Here, we report on a chemically-enzymatic method, employing a DNA polymerase and ligase, that enables a modified nucleoside, in the form of its 5'-triphosphate, to be incorporated into DNA fragment in a pre-determined site. Using such a protocol two double-stranded DNA fragments - a long one, 75 base pairs (bp), and a short one, 30bp in length - were pin-point labeled with 5-bromodeoxyuridine. Four DNA polymerases together with DHPLC for the inspection of reaction progress were used to optimize the process under consideration. As an ultimate test showing that the product possessing an assumed nucleotide sequence was actually obtained, we irradiated the synthesized oligonucleotide with UVB photons and analyzed its photoreactivity with the LC-MS method. Our results prove that a general approach enabling precise labeling of DNA with any nucleoside modification processed by DNA polymerase and ligase has been worked out.

  13. Autofluorescent Proteins as Photosensitizer in Eukaryontes

    Directory of Open Access Journals (Sweden)

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

    2009-01-01

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

  14. Primary mechanisms of photosensitization by furocoumarins

    Energy Technology Data Exchange (ETDEWEB)

    Grossweiner, L I

    1981-01-01

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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    Photosensitivity is a heritable abnormal cortical response to flickering light, manifesting as particular electroencephalographic changes, with or without seizures. Photosensitivity is prominent in a very rare epileptic encephalopathy due to de novo CHD2 mutations, but is also seen in epileptic...... encephalopathies due to other gene mutations. We determined whether CHD2 variation underlies photosensitivity in common epilepsies, specific photosensitive epilepsies and individuals with photosensitivity without seizures. We studied 580 individuals with epilepsy and either photosensitive seizures or abnormal...... without seizures. Zebrafish larvae with chd2 knockdown were tested for photosensitivity. Chd2 knockdown markedly enhanced mild innate zebrafish larval photosensitivity. CHD2 mutation is the first identified cause of the archetypal generalized photosensitive epilepsy syndrome, eyelid myoclonia...

  16. Flexible and fragmentable tandem photosensitive nanocrystal skins

    Science.gov (United States)

    Akhavan, S.; Uran, C.; Bozok, B.; Gungor, K.; Kelestemur, Y.; Lesnyak, V.; Gaponik, N.; Eychmüller, A.; Demir, H. V.

    2016-02-01

    We proposed and demonstrated the first account of large-area, semi-transparent, tandem photosensitive nanocrystal skins (PNSs) constructed on flexible substrates operating on the principle of photogenerated potential buildup, which avoid the need for applying an external bias and circumvent the current-matching limitation between junctions. We successfully fabricated and operated the tandem PNSs composed of single monolayers of colloidal water-soluble CdTe and CdHgTe nanocrystals (NCs) in adjacent junctions on a Kapton polymer tape. Owing to the usage of a single NC layer in each junction, noise generation was significantly reduced while keeping the resulting PNS films considerably transparent. In each junction, photogenerated excitons are dissociated at the interface of the semi-transparent Al electrode and the NC layer, with holes migrating to the contact electrode and electrons trapped in the NCs. As a result, the tandem PNSs lead to an open-circuit photovoltage buildup equal to the sum of those of the two single junctions, exhibiting a total voltage buildup of 128.4 mV at an excitation intensity of 75.8 μW cm-2 at 350 nm. Furthermore, we showed that these flexible PNSs could be bent over 3.5 mm radius of curvature and cut out in arbitrary shapes without damaging the operation of individual parts and without introducing any significant loss in the total sensitivity. These findings indicate that the NC skins are promising as building blocks to make low-cost, flexible, large-area UV/visible sensing platforms with highly efficient full-spectrum conversion.We proposed and demonstrated the first account of large-area, semi-transparent, tandem photosensitive nanocrystal skins (PNSs) constructed on flexible substrates operating on the principle of photogenerated potential buildup, which avoid the need for applying an external bias and circumvent the current-matching limitation between junctions. We successfully fabricated and operated the tandem PNSs composed of

  17. Efficient cyanoaromatic photosensitizers for singlet oxygen production: synthesis and characterization of the transient reactive species.

    Science.gov (United States)

    Ronzani, Filippo; Arzoumanian, Emmanuel; Blanc, Sylvie; Bordat, Patrice; Pigot, Thierry; Cugnet, Cyril; Oliveros, Esther; Sarakha, Mohamed; Richard, Claire; Lacombe, Sylvie

    2013-10-28

    In order to graft cyanoaromatic molecules onto various inert supports, we designed two new cyanoanthracene derivatives of benzo[b]triphenylene-9,14-dicarbonitrile (DBTP, 1), which already demonstrated good photosensitizing properties. We synthesized 3-(N-hydroxypropyl)carboxamido-9,14-dicyanobenzo[b]triphenylene, 3 and 3-(N-N0-Boc-aminohexyl)carboxamido-9,14-dicyanobenzo[b]triphenylene, 4 and compared their photophysical properties in acetonitrile relative to those of the parent compound 1 and its carboxylic derivative 9,14-dicyanobenzo[b]triphenylene-3-carboxylic acid, 2. The transient species were analysed and the quantum yields of singlet oxygen production (ΦΔ) determined in acetonitrile. The effect of chemical functionalization can be considered negligible, since absorption spectra, fluorescence emission spectra and fluorescence lifetimes do not significantly change with the substituent. The triplet-triplet absorption spectra and the triplet excited state lifetimes are similar for the whole series. For compounds 1-4 high values of ΦΔ, close to that of the standard sensitizer 1H-phenalen-1-one (PN, ΦΔ ≈ 1), and higher than that of the well-known photosensitizer 9,10-dicyanoanthracene (DCA), are due to very efficient intersystem crossing from the singlet to the triplet excited state and subsequent energy transfer to ground state oxygen ((3)O2). They belong to a class of very efficient photosensitizers, absorbing visible light and stable under irradiation, they may be functionalized without significant changes to their photophysical behaviour, and grafted onto various supports.

  18. Liposomal photosensitizers: potential platforms for anticancer photodynamic therapy

    Directory of Open Access Journals (Sweden)

    L.A. Muehlmann

    2011-08-01

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

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

    Science.gov (United States)

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

    2014-06-18

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

  20. Optical filters inhibiting television-induced photosensitive seizures.

    Science.gov (United States)

    Takahashi, Y; Sato, T; Goto, K; Fujino, M; Fujiwara, T; Yamaga, M; Ito, T; Isono, H; Kondo, N

    2001-11-27

    Televised images are the most common stimulus for provoking photosensitive seizures in photosensitive persons. To inhibit photosensitive seizures in photosensitive persons who do or do not have epilepsy, the authors sought nonpharmacologic methods for reducing the levels of photic stimulation of televised images. The authors found two types of pathophysiologic mechanisms (wavelength-dependent and quantity of light-dependent mechanisms) for photoparoxysmal responses (PPR). The authors tested two different types of optical filters, one reflecting long-wavelength red light selectively, which stimulates a wavelength-dependent mechanism, and the other absorbing light in the visible spectrum evenly (neutral density filters). Inhibiting effects of optical filters were studied by conventional intermittent photic stimulation (IPS) using strobe light and novel photic stimulation using flashing cathode ray tubes (CRT). Both filters individually inhibited PPR insufficiently (less than 50%). Compound optical filters, composed of both types of filters, can inhibit the PPR, approximately 90% for IPS and 95% for photic stimulation with CRT. These compound optical filters do not destroy chromaticity of emissions from the television's CRT. These compound filters may be useful to prevent seizures induced by television in photosensitive persons.

  1. Investigation of defects in highly photosensitive germanosilicate thin films

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-02-01

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

  2. Multifunctional Photosensitizer-Based Contrast Agents for Photoacoustic Imaging

    Science.gov (United States)

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

    2014-06-01

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

  3. Pharmaceutical development, composition and quantitative analysis of phthalocyanine as the photosensitizer for cancer photodynamic therapy.

    Science.gov (United States)

    Jiang, Zhou; Shao, Jingwei; Yang, Tingting; Wang, Jian; Jia, Lee

    2014-01-01

    Phthalocyanine (Pc) and its related derivatives are a class of functional materials that are easily activated by the light at a special wavelength. As such photosensitizer, Pc has been applied to photodynamic therapy (PDT), in addition to its broad applications in many fields, for both malignant and benign diseases. One of our long-term research focuses is to develop Pc for cancer therapy. Herein we briefly review mechanisms of action of Pc used for photodynamic therapy, its pharmaceutical development and molecular modification to enhance its drugability and improve its intracellular localization. We also describe the current status of the Pc derivatives under clinical investigation, and analyze the methods used for quantitative analysis of those Pc derivatives. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Drug discovery of antimicrobial photosensitizers using animal models.

    Science.gov (United States)

    Sharma, Sulbha K; Dai, Tianhong; Kharkwal, Gitika B; Huang, Ying-Ying; Huang, Liyi; De Arce, Vida J Bil; Tegos, George P; Hamblin, Michael R

    2011-01-01

    Antimicrobial photodynamic therapy (aPDT) is an emerging alternative to antibiotics motivated by growing problems with multi-drug resistant pathogens. aPDT uses non-toxic dyes or photosensitizers (PS) in combination with harmless visible of the correct wavelength to be absorbed by the PS. The excited state PS can form a long-lived triplet state that can interact with molecular oxygen to produce reactive oxygen species such as singlet oxygen and hydroxyl radical that kill the microbial cells. To obtain effective PS for treatment of infections it is necessary to use cationic PS with positive charges that are able to bind to and penetrate different classes of microbial cells. Other drug design criteria require PS with high absorption coefficients in the red/near infra-red regions of the spectrum where light penetration into tissue is maximum, high photostability to minimize photobleaching, and devising compounds that will selectively bind to microbial cells rather than host mammalian cells. Several molecular classes fulfill many of these requirements including phenothiazinium dyes, cationic tetrapyrroles such as porphyrins, phthalocyanines and bacteriochlorins, cationic fullerenes and cationic derivatives of other known PS. Larger structures such as conjugates between PS and cationic polymers, cationic nanoparticles and cationic liposomes that contain PS are also effective. In order to demonstrate in vivo efficacy it is necessary to use animal models of localized infections in which both PS and light can be effectively delivered into the infected area. This review will cover a range of mouse models we have developed using bioluminescent pathogens and a sensitive low light imaging system to non-invasively monitor the progress of the infection in real time. Effective aPDT has been demonstrated in acute lethal infections and chronic biofilm infections; in infections caused by Gram-positive, Gram-negative bacteria and fungi; in infections in wounds, third degree burns

  5. Redox-controlled photosensitization of nanocrystalline titanium dioxide.

    Science.gov (United States)

    Szaciłowski, Konrad; Macyk, Wojciech; Hebda, Maciej; Stochel, Grazyna

    2006-11-13

    Photosensitization of nanocrystalline titanium dioxide materials has been achieved by chemisorption of the pentacyanothiamineferrate(II) complex, which offers a relatively high redox potential that determines the photoelectrochemical properties of the photosensitized TiO(2). The adsorbed pentacyanoferrate complex binds to TiO(2) through the cyanide bridge and forms a new surface complex characterized by a metal-to-metal charge-transfer transition (MMCT) (Fe(II)-->Ti(IV)). The photosensitization can be observed only at low potentials at which Fe(II) moieties are present. Photocurrent switching between anodic and cathodic can be induced by varying either the photoelectrode potential or the wavelength of the incident light. Simple molecular modeling-together with spectroscopic and electrochemical measurements-allows the elucidation of the mechanism of the observed photoelectrochemical behavior.

  6. Characteristics of photosensitization of Pheophorbide a in liposomal media

    Institute of Scientific and Technical Information of China (English)

    杨红英; 李美芬; 张文庚; 赵红霞; 张志义

    1999-01-01

    Pheophorbide a (PPa), a decomposition product of chlorophyll a, is a photosensitizer. The photosensitization mechanisms (Type Ⅰ and Type Ⅱ) of PPa in simple buffer solutions and in buffer solutions containing double-layered DPPC liposomes have been studied using techniques of ESR, spin-trapping, spin-counteraction and laser flash photolysis. The results showed that adding DPPC liposomes to the buffer solution caused an increase of efficiency of generating 1O2 and PPa- by photoactivating PPa. The increase could be ascribed to the disaggregation of hydrophobic PPa caused by the addition of liposomes and the protective effect of liposomal media on the triplet state of PPa. It is concluded that the photosensitization of PPa in liposomal systems is different from that in simple aqueous solutions, and shows higher efficacy. The results will be useful to elucidating the mechanisms of photodynamic therapy of cancer.

  7. Dye-mediated photosensitization of murine neuroblastoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Sieber, F.; Sieber-Blum, M.

    1986-04-01

    The purpose of this study was to determine if photosensitization mediated by the fluorescent dye, merocyanine 540, could be used to preferentially kill murine neuroblastoma cells in simulated autologous remission marrow grafts. Simultaneous exposure of Neuro 2a or NB41A3 neuroblastoma cells to merocyanine 540 and white light reduced the concentration of in vitro-clonogenic tumor cells 50,000-fold. By contrast, the same treatment had little effect on the graft's ability to rescue lethally irradiated syngeneic hosts. Lethally irradiated C57BL/6J X A/J F1 mice transplanted with photosensitized mixtures of neuroblastoma cells and normal marrow cells (1:100 or 1:10) survived without developing neuroblastomas. It is conceivable that merocyanine 540-mediated photosensitization will prove useful for the extracorporeal purging of residual neuroblastoma cells from human autologous remission marrow grafts.

  8. Photosensitization in cattle and sheep caused by feeding Ammi majus (greater Ammi; Bishop's-Weed).

    Science.gov (United States)

    Dollahite, J W; Younger, R L; Hoffman, G O

    1978-01-01

    Feeding Ammi majus to cattle and sheep caused photosensitization in both species. It also caused photosensitization in human beings who had dermal contact with the plant and subsequent exposure to sunlight.

  9. Radical production from photosensitization of imidazoles

    Science.gov (United States)

    Corral Arroyo, P.; Gonzalez, L.; Steimer, S.; Aellig, R.; Volkamer, R. M.; George, C.; Bartels-Rausch, T.; Ammann, M.

    2015-12-01

    Reactions promoted by light are key in atmospheric chemistry. Some of them occur in the condensed phase of aerosols containing light absorbing organic compounds (George et al., 2015). This work explores the radical reactions initiated by near-UV light in mixtures of citric acid (CA) and imidazole-2-carboxaldehyde (IC) using NO as a probe molecule for HO2, by means of coated wall flow tube experiments. Citric acid may act as H atom or electron donor in condensed phase radical cycles. IC may act as a photosensitizer. The loss of NO was measured by a chemiluminescence detector. The dependence of the NO loss on the NO concentration, the IC/CA ratio in the film, relative humidity, light intensity, oxygen molar fraction were investigated as well as the HONO and NO2 yields. We also added halide salts to investigate the effect of a competing electron donor in the system and the output of halogens to the gas phase. We found a correlation between the loss of NO above the film and the molar ratio of IC/CA and the light intensity. The variation of the NO loss with oxygen corroborates a mechanism, in which the triplet excited state of IC is reduced by citric acid, to a reduced ketyl radical that transfers an electron to molecular oxygen, which in turn leads to production of HO2 radicals. Therefore, the NO loss in the gas phase is related to the production of HO2 radicals. Relative humidity had a strong impact on the HO2 output, which shows a maximum production rate at around 30%. The addition of halide ions (X- = Cl-, Br-, I-) increases the HO2 output at low concentration and decrease it at higher concentration when X2- radical ions likely scavenge HO2. We could preliminarily quantify for the first time the contribution of these processes to the oxidative capacity in the atmosphere and conclude that their role is significant for aerosol aging and potentially a significant source of halogen compounds to the gas phase.

  10. Photodynamic Inactivation of Candida albicans with Imidazoacridinones: Influence of Irradiance, Photosensitizer Uptake and Reactive Oxygen Species Generation.

    Directory of Open Access Journals (Sweden)

    Aleksandra Taraszkiewicz

    Full Text Available The increasing applicability of antifungal treatments, the limited range of available drug classes and the emergence of drug resistance in Candida spp. suggest the need for new treatment options. To explore the applicability of C. albicans photoinactivation, we examined nine structurally different imidazoacridinone derivatives as photosensitizing agents. The most effective derivatives showed a >10(4-fold reduction of viable cell numbers. The fungicidal action of the three most active compounds was compared at different radiant powers (3.5 to 63 mW/cm2, and this analysis indicated that 7 mW/cm2 was the most efficient. The intracellular accumulation of these compounds in fungal cells correlated with the fungicidal activity of all 9 derivatives. The lack of effect of verapamil, an inhibitor targeting Candida ABC efflux pumps, suggests that these imidazoacridinones are not substrates for ABC transporters. Thus, unlike azoles, a major class of antifungals used against Candida, ABC transporter-mediated resistance is unlikely. Electron paramagnetic resonance (EPR-spin trapping data suggested that the fungicidal light-induced action of these derivatives might depend on the production of superoxide anion. The highest generation rate of superoxide anion was observed for 1330H, 1610H, and 1611. Singlet oxygen production was also detected upon the irradiation of imidazoacridinone derivatives with UV laser light, with a low to moderate yield, depending on the type of compound. Thus, imidazoacridinone derivatives examined in the present study might act via mixed type I/type II photodynamic mechanism. The presented data indicate lack of direct correlation between the structures of studied imidazoacridinones, cell killing ability, and ROS production. However, we showed for the first time that for imidazoacridinones not only intracellular accumulation is necessary prerequisite of lethal photosensitization of C. albicans, but also localization within particular

  11. Photodynamic Inactivation of Candida albicans with Imidazoacridinones: Influence of Irradiance, Photosensitizer Uptake and Reactive Oxygen Species Generation.

    Science.gov (United States)

    Taraszkiewicz, Aleksandra; Szewczyk, Grzegorz; Sarna, Tadeusz; Bielawski, Krzysztof P; Nakonieczna, Joanna

    2015-01-01

    The increasing applicability of antifungal treatments, the limited range of available drug classes and the emergence of drug resistance in Candida spp. suggest the need for new treatment options. To explore the applicability of C. albicans photoinactivation, we examined nine structurally different imidazoacridinone derivatives as photosensitizing agents. The most effective derivatives showed a >10(4)-fold reduction of viable cell numbers. The fungicidal action of the three most active compounds was compared at different radiant powers (3.5 to 63 mW/cm2), and this analysis indicated that 7 mW/cm2 was the most efficient. The intracellular accumulation of these compounds in fungal cells correlated with the fungicidal activity of all 9 derivatives. The lack of effect of verapamil, an inhibitor targeting Candida ABC efflux pumps, suggests that these imidazoacridinones are not substrates for ABC transporters. Thus, unlike azoles, a major class of antifungals used against Candida, ABC transporter-mediated resistance is unlikely. Electron paramagnetic resonance (EPR)-spin trapping data suggested that the fungicidal light-induced action of these derivatives might depend on the production of superoxide anion. The highest generation rate of superoxide anion was observed for 1330H, 1610H, and 1611. Singlet oxygen production was also detected upon the irradiation of imidazoacridinone derivatives with UV laser light, with a low to moderate yield, depending on the type of compound. Thus, imidazoacridinone derivatives examined in the present study might act via mixed type I/type II photodynamic mechanism. The presented data indicate lack of direct correlation between the structures of studied imidazoacridinones, cell killing ability, and ROS production. However, we showed for the first time that for imidazoacridinones not only intracellular accumulation is necessary prerequisite of lethal photosensitization of C. albicans, but also localization within particular cellular

  12. Separation of porphyrin-based photosensitizer isomers by laser-induced fluorescence capillary electrophoresis.

    Science.gov (United States)

    Peng, Xuejun; Sternberg, Ethan; Dolphin, David

    2005-10-01

    Methods for the separation of photosensitizer isomers, such as benzoporphyrin derivative monoacid, benzoporphyrin ethyl monoacid, 2-[1-hexyloxyethyl]-2-devinylpyropheophorbide-a, diethyleneglycol diester benzoporphyrin derivative, tin ethyl etiopurpurin, and phthalocyanine tetrasulfonate, have been systematically developed by CE. Detection was accomplished by UV absorption at 214 nm or by LIF with excitation at 442/488 nm and emission at 690 nm. The effects of three major experimental parameters of buffer types, organic solvents, and surfactant additives are described. The optimized separation conditions were determined so as to provide satisfactory separation efficiency and analysis time. The methods are shown to be suitable for the separation and determination of porphyrin and phthalocyanines regioisomers, diastereoisomers, and enantiomers.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    A 75-year-old man suffering from rheumatoid arthritis, myxoedema and type II diabetes mellitus, presented with occasional double vision and photosensitivity. The patient underwent an MRI of the brain showing a tumour located in the right of the sphenoid bone. A subsequent diagnostic CT scan of th...

  14. Photosensitizers for tumor fluorescence and phothodynamic therapy of cancer

    NARCIS (Netherlands)

    H.L.L.M. van Leengoed (Eric)

    1993-01-01

    textabstractPhotosensitive dyes have great interest because of the attractive combination of fluorescence imaging and photochemical destruction of tumors. When detected early, tumors are more easy to treat, usually respond better to treatment and there is a reduced risk of spreading of the disease.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    Fe(II) complexes have long been assumed unsuitable as photosensitizers because of their low-lying nonemissive metal centered (MC) states, which inhibit electron transfer. Herein, we describe the excited-state relaxation of a novel Fe(II) complex that incorporates N-heterocyclic carbene ligands de...

  16. Development of proportional counters using photosensitive gases and liquids

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, D.F.

    1984-10-01

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

  17. Betacyanins pigments as photosensitizing agents for holographic recording medium

    Science.gov (United States)

    Toxqui-López, S.; Hernández-Hernández, E.; Santacruz-Vázquez, C.; Olivares-Pérez, A.; Santacruz-Vazquez, V.

    2014-02-01

    One of the natural most employed within the food industry are pigments of betalains by their solubility in water to give desired colorations in processed foods such as beverages, dairy, meat. However, this research shows that this type of pigments can be used as photosensitizing agents in the field of holographic recording materials.

  18. Solid state photosensitive devices which employ isolated photosynthetic complexes

    Science.gov (United States)

    Peumans, Peter; Forrest, Stephen R.

    2009-09-22

    Solid state photosensitive devices including photovoltaic devices are provided which comprise a first electrode and a second electrode in superposed relation; and at least one isolated Light Harvesting Complex (LHC) between the electrodes. Preferred photosensitive devices comprise an electron transport layer formed of a first photoconductive organic semiconductor material, adjacent to the LHC, disposed between the first electrode and the LHC; and a hole transport layer formed of a second photoconductive organic semiconductor material, adjacent to the LHC, disposed between the second electrode and the LHC. Solid state photosensitive devices of the present invention may comprise at least one additional layer of photoconductive organic semiconductor material disposed between the first electrode and the electron transport layer; and at least one additional layer of photoconductive organic semiconductor material, disposed between the second electrode and the hole transport layer. Methods of generating photocurrent are provided which comprise exposing a photovoltaic device of the present invention to light. Electronic devices are provided which comprise a solid state photosensitive device of the present invention.

  19. Synthesis and Characterization of Photosensitive Polyimides for Optical Applications

    Science.gov (United States)

    Kim, Kye-Hyun

    1995-11-01

    The objective of this research was to prepare photosensitive polyimides for optical applications. The work was begun with the synthesis of a series of poly(amic esters) containing cinnamyl groups. However, these systems required high imidization temperatures where they darkened considerably. Two new photosensitive end-capping agents, i.e., 6-(4-aminophenoxy)hexyl methacrylate, and di(2-(methacryloyloxy)ethyl) 5-aminoisophthalate, for polyimides were also prepared. These agents were used along with 2,2^' -bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2^'-bis(trifluoromethyl) -4,4^' -diaminobiphenyl (PFMB) to prepare a series of methacrylate end-capped imide oligomers. However, the oligomers required long exposures to UV-radiation to affect cure. To improve their photosensitivity, multifunctional additives and photoinitiators were used. A difunctional end-capped oligomer that contained trimethylolpropane triacrylate (TMPTA) and trimethylbenzoyldiphenyl phosphine oxide (TMDPO) was highly photosensitive and displayed good photo-patterning properties. The third approach involved the synthesis of a diamine monomer in which methacrylate moieties were attached to the 2- and 2^ '-positions of biphenyl structures. The monomer, i.e., 2,2^'-dimethacryloyloxy -4,4^'-diaminobiphenyl (DMB), was polymerized with commercially available dianhydrides such as 6FDA and 4,4^' -oxydiphthalic anhydride (ODPA). The polyimides obtained were optically transparent and soluble in common organic solvents such as acetone and chloroform. The polymers were highly photosensitive and displayed good photo-patterning properties. The polymers, which afforded high-resolution patterns, did not develop color or shrink during UV-exposure and thermal curing.

  20. Review of selective accumudation of photosensitizers with different chemical structure in tumor tissue

    Directory of Open Access Journals (Sweden)

    E. A. Machinskaya

    2013-01-01

    Full Text Available The review of available theories explaining mechanisms of photosensitizer selective accumulation in tumor tissue is represented in the article. Variants associated with both targeted delivery of compounds with different chemical structure to tumor and low elimination rate of photosensitizers in the tumor are described. Details of tumor cell up-take of photosensitizer bounded with lipoproteins due to increased expression of low solidity lipoproteins receptors comparing with normal cells; mechanisms of photosensitizer accumulation in tumor tissue due to phagocytosis by macrophages localized in this area; mechanisms of binding of porphyrin-based photosensitizer by collagen fibers, production of which is increased in tumor cells, and other mechanisms are reviewed. Perspectives of practical application of knowledge about mechanisms of selective accumulation for induced increase in selectiveness of photosensitizer accumulation in tumor through targeted delivery of agent to pathological tissues are shown. Analysis of world trends in the search of transport systems for photosensitizers is performed. 

  1. Extensive burns caused by the abusive use of photosensitizing agents.

    Science.gov (United States)

    Braye, F; Latarjet, J; Foyatier, J L; Comparin, J P; Tranchand, P; Boucaud, C

    1997-01-01

    Psoralens are photosensitizing agents used in dermatology as reinforcements in psoralen ultraviolet A-range therapy. We report observations of 14 young women hospitalized for severe burns caused by abusive use of psoralens. The burns were of superficial and deep second-degree depth and covered more than 76% of the body surface on average. All patients needed fluid resuscitation. Hospital stay was 11 days on average. Healing was obtained without skin grafting in all cases. Among the six patients who responded to the mailed questionnaire, negative effects are now present in all patients as inflammatory peaks. Two patients have esthetic sequelae such as dyschromia and scars. The misuse of photosensitizing agents poses many problems. These accidents are very expensive. The largeness of the burned surface can involve a fatal prognosis. And finally, one can suspect that a much larger portion of the population regularly uses these products without any serious accident. In this case carcinogenesis can be expected.

  2. Photosensitive cadmium telluride thin-film field-effect transistors.

    Science.gov (United States)

    Yang, Gwangseok; Kim, Donghwan; Kim, Jihyun

    2016-02-22

    We report on the graphene-seeded growth and fabrication of photosensitive Cadmium telluride (CdTe)/graphene hybrid field-effect transistors (FETs) subjected to a post-growth activation process. CdTe thin films were selectively grown on pre-defined graphene, and their morphological, electrical and optoelectronic properties were systemically analyzed before and after the CdCl2 activation process. CdCl2-activated CdTe FETs showed p-type behavior with improved electrical features, including higher electrical conductivity (reduced sheet resistance from 1.09 × 10(9) to 5.55 × 10(7) Ω/sq.), higher mobility (from 0.025 to 0.20 cm2/(V·s)), and faster rise time (from 1.23 to 0.43 s). A post-growth activation process is essential to fabricate high-performance photosensitive CdTe/graphene hybrid devices.

  3. Surface Free Energy Determination of APEX Photosensitive Glass

    Directory of Open Access Journals (Sweden)

    William R. Gaillard

    2016-02-01

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

  4. Surface Free Energy Determination of APEX Photosensitive Glass

    OpenAIRE

    William R. Gaillard; Emanuel Waddell; Williams, John D.

    2016-01-01

    Surface free energy (SFE) plays an important role in microfluidic device operation. Photosensitive glasses such as APEX offer numerous advantages over traditional glasses for microfluidics, yet the SFE for APEX has not been previously reported. We calculate SFE with the Owens/Wendt geometric method by using contact angles measured with the Sessile drop technique. While the total SFE for APEX is found to be similar to traditional microstructurable glasses, the polar component is lower, which i...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  6. Photosensitized damage to telomere overhang and telomerase RNA by riboflavin

    Institute of Scientific and Technical Information of China (English)

    Yuxia Liu; Fuqiang Du; Weizhen Lin; Tiecheng Tu; Wenxin Li; Nianyun Lin

    2008-01-01

    By ESR spin elimination and photodeavage assay, the mechanisms of one-electron oxidation damage of oligonucleotides by excited triplet state of riboflavin (Rb) have been elucidated. The results demonstrate that Rb, an endogenous photosensitizer, is capable of cleaving single-stranded telomeric overhang and the template region of telomerase RNA under UVA irradiation, resulting in blocking of reverse transcription of telomeric DNA which leads to the apoptosis of cancer cells ultimately.

  7. Development of Polymeric Cargo for Delivery of Photosensitizer in Photodynamic Therapy

    Directory of Open Access Journals (Sweden)

    Byoung-chan Bae

    2012-01-01

    Full Text Available Photodynamic therapy (PDT, which employs photosensitizers (PSs, a light source with appropriate wavelength, and oxygen molecules, has potential for the treatment of various tumors and nononcological diseases due to its high efficiency in directly producing cellular death, vascular shutdown, and immune activation. After the clinical success of Photofrin (porphyrin derivative, many PSs were developed with improved optical and chemical properties. However, some weak points such as low solubility and nonspecific phototoxicity induced by hydrophobic PSs still remain. In order to overcome these problems, various polymeric carriers for PS delivery have been intensively developed. Here, we report recent approaches to the development of polymeric carriers for PS delivery and discuss the physiological advantages of using polymeric carriers in PDT. Therefore, this paper provides helpful information for the design of new PSs without the weaknesses of conventional ones.

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

    Directory of Open Access Journals (Sweden)

    Reena Rai

    2016-01-01

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

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

    Science.gov (United States)

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

    2017-09-01

    Moderate consumption of red wine provides beneficial effects to health. This is attributed to polyphenol compounds present in wine such as resveratrol, quercetin, gallic acid, rutin, and vanillic acid. The amount of these antioxidants is variable; nevertheless, the main beneficial effects of red wine are attributed to resveratrol. However, it has been found that resveratrol and quercetin are able to photosensitize singlet oxygen generation and conversely, gallic acid acts as quencher. Therefore, and since resveratrol and quercetin are some of the most important antioxidants reported in red wines, the aim of this research was to evaluate the photosensitizing ability of 12 red wine extracts through photo-oxidation of ergosterol. The presence of (1) O2 was detected by ergosterol conversion into peroxide of ergosterol through (1) H NMR analysis. Our results showed that 10 wine extracts were able to act as photosensitizers in the generation of singlet oxygen. The presence of (1) O2 can damage other compounds of red wine and cause possible organoleptic alterations. Finally, although the reaction conditions employed in this research do not resemble the inherent conditions in wine making processing or storing, or even during its consumption, this knowledge could be useful to prevent possible pro-oxidant effects and avoid detrimental effects in red wines. © 2017 Institute of Food Technologists®.

  10. Cell death mechanisms vary with photodynamic therapy dose and photosensitizer

    Science.gov (United States)

    He, Jin; Oleinick, Nancy L.

    1995-03-01

    Mouse lymphoma L5178Y-R cells respond to photodynamic therapy (PDT) by undergoing rapid apoptosis, which is induced by PDT-activated signal transduction initiating in the damaged cellular membranes. To relate the level of PDT damage and photosensitizer to the mechanism of cell death, apoptosis has been detected by agarose gel electrophoresis of fragmented DNA and quantified by flow cytometry of cells after staining with Hoechst33342 and propidium iodide, a technique which can distinguish between live, apoptotic, and necrotic cells. When the silicon phthalocyanine Pc 4 or Pc 12 served as photosensitizer, lethal doses (as defined by clonogenic assay) of PDT induced apoptosis in essentially all cells, whereas supralethal doses prevented the characteristic degradation of DNA into oligonucleosomal fragments. In contrast with aluminum phthalocyanine (AlPc) cells died by apoptosis after all doses studied. It appears that high PDT doses with Pc 4 or Pc 12 damage enzymes needed to carry out the program of apoptosis; the absence of this effect with AlPc suggests either a different intracellular location or different photocytotoxic mechanism for the two photosensitizers.

  11. Fourier transform infrared spectroscopy (FTIR) characterization of the interaction of anti-cancer photosensitizers with dendrimers.

    Science.gov (United States)

    Dabrzalska, Monika; Benseny-Cases, Nuria; Barnadas-Rodríguez, Ramon; Mignani, Serge; Zablocka, Maria; Majoral, Jean-Pierre; Bryszewska, Maria; Klajnert-Maculewicz, Barbara; Cladera, Josep

    2016-01-01

    The systemic or local administration of a photosensitizer for photodynamic therapy is highly limited by poor selectivity, rapid deactivation and long-lasting skin toxicity due to unfavorable biodistribution. Drug delivery systems based on nanocarriers may help specific and effective delivery of photosensitizers. In the present paper, the interaction of two photosensitizers, methylene blue and rose bengal, with phosphorous cationic and anionic dendrimers as potential nanocarriers, has been characterized. A novel method is presented based on the analysis of the infrared spectra of mixtures of photosensitizer and dendrimer. The capacity of dendrimers to bind the photosensitizers has been evaluated by obtaining the corresponding binding curves. It is shown that methylene blue interacts with both cationic and anionic dendrimers, whereas rose bengal only binds to the cationic ones. Dendrimers are shown to be potential nanocarriers for a specific delivery of both photosensitizers.

  12. Comparison between 5,10,15,20-tetraaryl- and 5,15-diarylporphyrins as photosensitizers: synthesis, photodynamic activity, and quantitative structure-activity relationship modeling.

    Science.gov (United States)

    Banfi, Stefano; Caruso, Enrico; Buccafurni, Loredana; Murano, Roberto; Monti, Elena; Gariboldi, Marzia; Papa, Ester; Gramatica, Paola

    2006-06-01

    The synthesis of a panel of seven nonsymmetric 5,10,15,20-tetraarylporphyrins, 13 symmetric and nonsymmetric 5,15-diarylporphyrins, and one 5,15-diarylchlorin is described. In vitro photodynamic activities on HCT116 human colon adenocarcinoma cells were evaluated by standard cytotoxicity assays. A predictive quantitative structure-activity relationship (QSAR) regression model, based on theoretical holistic molecular descriptors, of a series of 34 tetrapyrrolic photosensitizers (PSs), including the 24 compounds synthesized in this work, was developed to describe the relationship between structural features and photodynamic activity. The present study demonstrates that structural features significantly influence the photodynamic activity of tetrapyrrolic derivatives: diaryl compounds were more active with respect to the tetraarylporphyrins, and among the diaryl derivatives, hydroxy-substituted compounds were more effective than the corresponding methoxy-substituted ones. Furthermore, three monoarylporphyrins, isolated as byproducts during diarylporphyrin synthesis, were considered for both photodynamic and QSAR studies; surprisingly they were found to be particularly active photosensitizers.

  13. Self-assembling properties of porphyrinic photosensitizers and their effect on membrane interactions probed by NMR spectroscopy.

    Science.gov (United States)

    Vermathen, Martina; Marzorati, Mattia; Bigler, Peter

    2013-06-13

    Aggregation and membrane penetration of porphyrinic photosensitizers play crucial roles for their efficacy in photodynamic therapy. The current study was aimed at comparing the aggregation behavior of selected photosensitizers and correlating it with membrane affinity. Self-assembling properties of 15 amphiphilic free-base chlorin and porphyrin derivatives bearing carboxylate substituents were studied in phosphate buffered saline (PBS) by (1)H NMR spectroscopy, making use of ring current induced aggregation shifts. All compounds exhibited aggregation in PBS to a different degree with dimers or oligomers showing slow aggregate growth over time. Aggregate structures were proposed on the basis of temperature dependent chemical shift changes. All chlorin compounds revealed similar aggregation maps with their hydrophobic sides overlapping and their carboxylate groups protruding toward the exterior. In contrast, for the porphyrin compounds, the carboxylate groups were located in overlapping regions. Membrane interactions were probed using 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayer vesicles and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) micelles as models. The chlorin derivatives had higher membrane affinity and were all monomerized by DHPC micelles as opposed to the porphyrin compounds. The observed differences were attributed to the different aggregate structures proposed for the chlorin and porphyrin derivatives. Free accessibility of the carboxylate groups seemed to promote initial surface interaction with phospholipid bilayers and micelles.

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

    Science.gov (United States)

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

    2013-02-01

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

  15. Nanoparticles improve biological functions of phthalocyanine photosensitizers used for photodynamic therapy.

    Science.gov (United States)

    Jia, Xiao; Jia, Lee

    2012-10-01

    Photodynamic therapy (PDT) is a new technology using photodynamic effect for disease diagnosis and treatment. It is a two-step technique involving the uptake of a photosensitizer by cancer tissue followed by light irradiation that excites the photosensitizer to produce highly reactive oxygen species, the latter execute apoptosis of cancerous cells. As a second-generation of photosensitizers, phthalocyanine demonstrates higher absorption in the 650-800 nm range and short tissue accumulation compared to their first generation. However, many potent phthalocyanine photosensitizers are hydrophobic and poorly water-soluble, which limit their therapeutic applications. As a result, advanced delivery systems and different strategies are called for to improve the effectiveness of PDT. Facts have proved that using nanoparticles as carries of photosensitizers is a very promising route. Nanoparticles have the potentials to increase photosensitizers' aqueous solubility, bioavailability and stability, and deliver photosensitizers to the target tissues. This article reviewed the commonly-used nanoparticles, including colloid gold, quantum dots, paramagnetic nanoparticles, silica-based materials, polymer-based nanoparticles, as potential delivery systems for phthalocyanine photosensitizers, and summarized the improved biological functions of phthalocyanine photosensitizers in PDT.

  16. Efficient H{sub 2}-producing photo-catalytic systems based on cyclo-metallated iridium- and tricarbonyl-rhenium-diimine photosensitizers and cobaloxime catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Fihri, A.; Artero, V.; Fontecave, M. [Univ Grenoble 1, Lab Chim et Biol Metaux, Grenoble (France); Fihri, A.; Artero, V.; Fontecave, M. [CNRS, UMR 5249, F-75700 Paris (France); Fihri, A.; Artero, V.; Fontecave, M. [CEA, DSV, iRTSV, F-38054 Grenoble 9 (France); Pereira, A. [CEA, DRT, Liten, DTNM, LTS, Grenoble (France)

    2008-07-01

    Quantum yield values up to 16% under visible irradiation associated with high turnover frequencies ({approx} 50 h{sup -1}) and stability (up to 273 turnovers), characterize the new photo-catalytic systems for hydrogen production, based on diimine derivatives of ruthenium, cyclo-metallated iridium or tricarbonyl-rhenium as photosensitizers and cobaloxime H{sub 2}-evolving catalytic centers, which are among the most efficient molecular systems reported so far and compete with some platinum-based systems. (authors)

  17. Photodynamic and Nail Penetration Enhancing Effects of Novel Multifunctional Photosensitizers Designed for The Treatment of Onychomycosis.

    Science.gov (United States)

    Smijs, Threes; Dame, Zoë; de Haas, Ellen; Aans, Jan-Bonne; Pavel, Stan; Sterenborg, Henricus

    2014-01-01

    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.

  18. Polyester-based thin films with high photosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    POTTER,KELLY SIMMONS; POTTER JR.,BARRETT G.; WHEELER,DAVID R.; JAMISON,GREGORY M.

    2000-02-29

    A great deal of research has been done to understand the photosensitive optical response of inorganic glasses, which exhibit a permanent, photo-induced refractive index change due to the presence of optically active point defects in the glass structure. In the present work, the authors have performed a preliminary study of the intrinsic photosensitivity of a polyester containing a cinnamylindene malonate group (CPE, a photo- and thermal-crosslinkable group) for use in photonic waveguide devices. Thin films of CPE (approximately 0.5 microns thick) were spun onto fused silica substrates. Optical absorption in the thin films was evaluated both before and after exposure to UV radiation sources. It was found that the polyester exhibits two dominant UV absorption bands centered about 240 nm and 330 nm. Under exposure to 337 nm radiation (nitrogen laser) a marked bleaching of the 330 nm band was observed. This band bleaching is a direct result of the photo-induced crosslinking in the cinnamylindene malonate group. Exposure to 248 nm radiation (excimer laser), conversely, resulted in similar bleaching of the 330 nm band but was accompanied by nearly complete bleaching of the higher energy 240 nm band. Based on a Kramers-Kronig analysis of the absorption changes, refractive index changes on the order of {minus}10{sup {minus}2} are estimated. Confirmation of this calculation has been provided via ellipsometry which estimates a refractive index change at 632 nm of {minus}0.061 {+-} 0.002. Thus, the results of this investigation confirm the photosensitive potential of this type of material.

  19. Photosensitivity to piroxicam: absence of cross-reaction with tenoxicam

    OpenAIRE

    Gonçalo, Margarida; Figueiredo, A; Tavares, P.; Fontes-Ribeiro, CA; Teixeira, F.; Poiares-Baptista, A

    1992-01-01

    We studied 2 groups of patients. One group of 10 patients had a photosensitive eruption to piroxicam. Another group of 24 patients had positive patch test reactions to thimerosal and thiosalicylic acid and had never taken piroxicam or tenoxicam. Patients were patch tested with thimerosal 0.1% pet., thiosalicylic acid 0.1% pet., salicylic acid 2.0% pet., piroxicam 1 and 5% pet. and tenoxicam 1 and 5% pet. Photopatch tests were also performed with piroxicam and tenoxicam. All 10 patients with p...

  20. Analysis of Photosensitivity of Copolymer Optical Fibre Preform

    Institute of Scientific and Technical Information of China (English)

    MA Hui; LI Zeng-Chang; MING Hai; ZHANG Qi-Jin; TAM Hwa-Yaw; ZHANG Yong-Sheng; ZHANG Tao; WANG Pei; XIE Jian-Ping

    2004-01-01

    @@ The photosensitivity of copolymer optical fibre preform is analysed in comparison with the doped one. The effects of write conditions such as pump power and pump time have been studied. Then, the preform is drawn into single mode polymer optical fibre with core refractive index of 1.499, and core-cladding refractive-index difference of 0.008. Long-period birefringence gratings with period of 120um are fabricated in the fibre. The duty cycle is 50%, and the refractive index change in the exposed area is about 1 × 10-3.

  1. Dosimetry of photosensitization by ultraviolet in patients treated with Haloperidol and Piportil

    Energy Technology Data Exchange (ETDEWEB)

    Barros, M. de (Paraiba Univ., Joao Pessoa (Brazil). Dept. de Fisiologia e Patologia); Albuquerque, M.S. (Hospital Colonia Juliano Moreira, Paraiba (Brazil)); Araujo, C.C. (Paraiba Univ., Joao Pessoa (Brazil). Dept. de Psicologia)

    It has been postulated that visible light on UV may induce photosensitization in chronic psycotics, under phenotiazine or butyrofenone therapy. The possible sensitization with UV, in patients with Haloperidol (Johnson and Johnson) or Piportil (Rhodia) treatments is described. Under experimental conditions, a surpassable photosensitizations in reaction groups aren't found, when paired with the control ones.

  2. Single Molecule Atomic Force Microscopy Studies of Photosensitized Singlet Oxygen Behavior on a DNA Origami Template

    DEFF Research Database (Denmark)

    Helmig, Sarah Wendelboe; Rotaru, Alexandru; Arian, Dumitru

    2010-01-01

    photosensitizer molecule conjugated to a selected DNA origami staple strand on an origami structure. We demonstrate a distance-dependent oxidation of organic moieties incorporated in specific positions on DNA origami by singlet oxygen produced from a single photosensitizer located at the center of each origami....

  3. PREPARATION AND APPLICATION OF PHOTOSENSITIVE COPOLYMERS FOR PDP BARRIER RIBS FORMED BY PHOTOLITHOGRAPHY

    Institute of Scientific and Technical Information of China (English)

    Tao Zhang; Qian-wen Dong; Wei Zhang; Jie Wei

    2013-01-01

    In this work,the photosensitive paste was prepared.It was comprised of inorganic particles and a photosensitive organic component.The inorganic particles included glass,ceramics,and metals.The organic component should contain at least the following photosensitive materials:photosensitive monomers,photoreactive copolymer and photopolymerization initiators.The photoreactive copolymer played a role of an adhesive in the photosensitive paste.Meanwhile in the development stage,the carboxyl groups of the copolymer reacted with the alkalescent developer.Following this,the unexposed part must be removed and an excellent pattern can be formed.A series of three-component acrylic copolymers (MAA/St/MMA) were designed,and then synthesized via free radical polymerization.Subsequently glycidyl methacrylate (GMA) was employed to modify the prepared copolymers through ring-opening reactions between the carboxyl groups and the epoxide groups.Eventually the photosensitive copolymers were obtained and used to form the barrier ribs of PDPs.The chemical structure,glass transition temperature,acid value and molecular weight of photosensitive copolymers had different effects on the structure and pattern of PDP barrier ribs.Through analyzing effects of different polymer performance parameters on the patterns of barrier ribs,the optimal photosensitive copolymer was acquired.

  4. Investigation of the oxidation mechanisms of limonene photosensitized by imidazole-2-carboxaldehyde

    Science.gov (United States)

    Rossignol, Stéphanie; Tinel, Liselotte; Aregahegn, Kifle; George, Christian

    2013-04-01

    Recent studies have revealed the significant formation of light absorbing materials, including imidazole and imidazole derivatives, in aqueous aerosol mimics in the presence of both ammonium sulphate and glyoxal (Galloway et al. 2009; Yu et al. 2011; Kampf et al. 2012). Besides the potential impact on radiative properties of secondary organic aerosols, our team has shown that imidazole-2-carboxaldehyde (IC) acts as a photosensitizer, initiating aerosols growth in the presence of gaseous limonene and UV/visible light (Aregahegn et al., abstract submitted). This work focuses on the characterisation of the chemical mechanisms leading to this aerosols growth, and on the major products identification. The molecular composition of organic/aqueous solutions exposed to UV/visible light and containing IC and limonene is followed in time by HR-ESI-MS/MS in positive and negative modes. Limonene consumption is followed by HPLC-UV. HR-ESI-MS/MS analyses are performed in parallel on IC/ammonium sulphate aerosols exposed to gaseous limonene and UV/visible light, in particular to assess the relevance of in solution experiments. Besides, the lifetime of the triplet state of IC in aqueous/organic solutions in the presence of different terpenes is monitored by laser photolysis experiments and compared in order to explain the first steps of the photosensitized reaction. First HR-ESI-MS/MS results show the formation of the major "traditional" limonene oxidation products (e.g., coming from gas phase limonene ozonolysis) during the irradiation of organic solutions containing IC and limonene: limononaldehyde, keto-limononaldehyde, limonic acid, limononic acid ... Hundreds of other oxygenated species are however detected, typically with a number of carbon atoms ranging from 4 to 20 and with O/C ratios ranging from 0.2 to 0.7. Monomers and dimers of limonene oxidation products are observed but species with lower carbon numbers than monomeric compounds are predominant. Moreover, and

  5. Histidine oxidation photosensitized by pterin: pH dependent mechanism.

    Science.gov (United States)

    Castaño, Carolina; Oliveros, Esther; Thomas, Andrés H; Lorente, Carolina

    2015-12-01

    Aromatic pterins accumulate in the skin of patients suffering from vitiligo, a chronic depigmentation disorder, due to the oxidation of tetrahydrobiopterin, the biologically active form of pterins. In this work, we have investigated the ability of pterin, the parent compound of aromatic pterins, to photosensitize the oxidation of histidine in aqueous solutions under UV-A irradiation. Histidine is an α-amino acid with an imidazole functional group, and is frequently present at the active sites of enzymes. The results highlight the role of the pH in controlling the competition between energy and electron transfer mechanisms. It has been previously demonstrated that pterins participate as sensitizers in photosensitized oxidations, both by type I (electron-transfer) and type II mechanisms (singlet oxygen ((1)O2)). By combining different analytical techniques, we could establish that a type I photooxidation was the prevailing mechanism at acidic pH, although a type II mechanism is also present, but it is more important in alkaline solutions.

  6. The circadian response of intrinsically photosensitive retinal ganglion cells.

    Directory of Open Access Journals (Sweden)

    Andrew J Zele

    Full Text Available Intrinsically photosensitive retinal ganglion cells (ipRGC signal environmental light level to the central circadian clock and contribute to the pupil light reflex. It is unknown if ipRGC activity is subject to extrinsic (central or intrinsic (retinal network-mediated circadian modulation during light entrainment and phase shifting. Eleven younger persons (18-30 years with no ophthalmological, medical or sleep disorders participated. The activity of the inner (ipRGC and outer retina (cone photoreceptors was assessed hourly using the pupil light reflex during a 24 h period of constant environmental illumination (10 lux. Exogenous circadian cues of activity, sleep, posture, caffeine, ambient temperature, caloric intake and ambient illumination were controlled. Dim-light melatonin onset (DLMO was determined from salivary melatonin assay at hourly intervals, and participant melatonin onset values were set to 14 h to adjust clock time to circadian time. Here we demonstrate in humans that the ipRGC controlled post-illumination pupil response has a circadian rhythm independent of external light cues. This circadian variation precedes melatonin onset and the minimum ipRGC driven pupil response occurs post melatonin onset. Outer retinal photoreceptor contributions to the inner retinal ipRGC driven post-illumination pupil response also show circadian variation whereas direct outer retinal cone inputs to the pupil light reflex do not, indicating that intrinsically photosensitive (melanopsin retinal ganglion cells mediate this circadian variation.

  7. Design and fabrication of erbium doped photosensitive fibers

    Institute of Scientific and Technical Information of China (English)

    LI Jian; LIU Peng; LU ShaoHua; WANG Jing; MAO XiangQiao; WEI Huai; FU YongJun; ZHENG Kai; NING TiGang; LI TangJun; JIAN ShuiSheng

    2009-01-01

    A kind of erbium doped photosensitive fiber (EDPF) was proposed and fabricated, whose core was made of double layers named photosensitive layer and erbium doped layer. The double-layer core de-sign can overcome difficulties in fabrication of EDPF with single core design, i.e. the conflict between the high consistency rare earth doping and high consistency germanium doping. A sample was fabri-cated through the modified chemical vapor deposition method combined with solution doping tech-nique. The peak absorption coefficient was 48.80 dB/m at 1.53 μm, the background loss was lower than 0.1 dB/m, and the reflectivity of the fiber Brag gratings (FBG) written directly on the sample fiber was up to 97.3% by UV-writing technology. Moreover, a C band tunable fiber laser was fabricated using the sample fiber, in which a uniform FBG was written directly on EDPFs as a reflector. A single wavelength lasing with a maximum wavelength tuning range of 1555.2--1558.0 nm was achieved experimentally.Within this tuning range, the full-width at half maximum (FWHM) of the laser output was smaller than 0.015 nm and the side mode suppression ratio (SMSR) was better than 50 dB.

  8. Design and fabrication of erbium doped photosensitive fibers

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A kind of erbium doped photosensitive fiber(EDPF) was proposed and fabricated,whose core was made of double layers named photosensitive layer and erbium doped layer.The double-layer core de-sign can overcome difficulties in fabrication of EDPF with single core design,i.e.the conflict between the high consistency rare earth doping and high consistency germanium doping.A sample was fabri-cated through the modified chemical vapor deposition method combined with solution doping tech-nique.The peak absorption coefficient was 48.80 dB/m at 1.53 μm,the background loss was lower than 0.1 dB/m,and the reflectivity of the fiber Brag gratings(FBG) written directly on the sample fiber was up to 97.3% by UV-writing technology.Moreover,a C band tunable fiber laser was fabricated using the sample fiber,in which a uniform FBG was written directly on EDPFs as a reflector.A single wavelength lasing with a maximum wavelength tuning range of 1555.2―1558.0 nm was achieved experimentally.Within this tuning range,the full-width at half maximum(FWHM) of the laser output was smaller than 0.015 nm and the side mode suppression ratio(SMSR) was better than 50 dB.

  9. Intermolecular Structural Change for Thermo-Switchable Polymeric photosensitizer

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-31

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

  10. Photosensitization in sheep fed Ammi majus (Bishop's weed) seed.

    Science.gov (United States)

    Witzel, D A; Dollahite, J W; Jones, L P

    1978-02-01

    Ammi majus (bishop's weed) grows on the coastal region of southern United States and in other parts of the world. This plant causes severe photosensitization in livestock and probably contributes to the severe photosensitization outbreaks seen in Texas. Sheep were fed finely ground seed of A majus via stomach tube at dose rates of 1, 2, 4, and 8 g/kg of body weight and exposed to sunlight. The single dose of 8 g/kg produced severe clinical signs (in 24 to 48 hours): cloudy cornea, conjunctivokeratitis, photophobia, and edema of the muzzle, ears, and vulva. Daily dosing at 2 and 4 g/kg produced (in 72 to 96 hours) similar signs, whereas the smallest dose (1 g/kg) produced mild irritation of the muzzle. Pathologic changes included (1) corneal edema and marked neutrophilic infiltration of the cornea and corneal/ciliary process, (2) subacute ulcerative and exudative dermatitis of the skin of ears, muzzle, and vulva, and (3) mild focal tubular degeneration (vacuolar type) of the kidney.

  11. Long-wavelength photosensitivity in coral planula larvae.

    Science.gov (United States)

    Mason, Benjamin M; Cohen, Jonathan H

    2012-04-01

    Light influences the swimming behavior and settlement of the planktonic planula larvae of coral, but little is known regarding the photosensory biology of coral at this or any life-history stage. Here we used changes in the electrical activity of coral planula tissue upon light flashes to investigate the photosensitivity of the larvae. Recordings were made from five species: two whose larvae are brooded and contain algal symbionts (Porites astreoides and Agaricia agaricites), and three whose larvae are spawned and lack algal symbionts (Acropora cervicornis, Acropora palmata,and Montastrea faveolata). Photosensitivity originated from the coral larva rather than from, or in addition to, its algal symbionts as species with and without symbionts displayed similar tissue-level electrical responses to light. All species exhibited as much (or more) sensitivity to red stimuli as to blue/green stimuli, which is consistent with a role for long-wavelength visible light in the preference for substrata observed during settlement and in facilitating vertical positioning of larvae in the water column.

  12. Prostaglandin E₂ is critical for the development of niacin-deficiency-induced photosensitivity via ROS production.

    Science.gov (United States)

    Sugita, Kazunari; Ikenouchi-Sugita, Atsuko; Nakayama, Yasuko; Yoshioka, Haruna; Nomura, Takashi; Sakabe, Jun-Ichi; Nakahigashi, Kyoko; Kuroda, Etsushi; Uematsu, Satoshi; Nakamura, Jun; Akira, Shizuo; Nakamura, Motonobu; Narumiya, Shuh; Miyachi, Yoshiki; Tokura, Yoshiki; Kabashima, Kenji

    2013-10-17

    Pellagra is a photosensitivity syndrome characterized by three "D's": diarrhea, dermatitis, and dementia as a result of niacin deficiency. However, the molecular mechanisms of photosensitivity dermatitis, the hallmark abnormality of this syndrome, remain unclear. We prepared niacin deficient mice in order to develop a murine model of pellagra. Niacin deficiency induced photosensitivity and severe diarrhea with weight loss. In addition, niacin deficient mice exhibited elevated expressions of COX-2 and PGE syntheses (Ptges) mRNA. Consistently, photosensitivity was alleviated by a COX inhibitor, deficiency of Ptges, or blockade of EP4 receptor signaling. Moreover, enhanced PGE2 production in niacin deficiency was mediated via ROS production in keratinocytes. In line with the above murine findings, human skin lesions of pellagra patients confirmed the enhanced expression of Ptges. Niacin deficiency-induced photosensitivity was mediated through EP4 signaling in response to increased PGE2 production via induction of ROS formation.

  13. Two-photon spectroscopic behaviors and photodynamic effect on the BEL-7402 cancer cells of the new chlorophyll photosensitizer

    Institute of Scientific and Technical Information of China (English)

    ZHAO PeiDe; ZHANG GuiLan; CHEN WenJu; CHEN Ping; TANG GuoQing; LIU JinWei; LIN Lie; GUO Peng; YU Qing; YAO JianZhong; MA DongMing

    2008-01-01

    The spectroscopic properties of a new chlorophyll derivate photosensitizer (CDP) are studied under the excitation wavelengths at 800 and 400 nm using femtosecond pulses from a Ti: sapphire laser. The damaging effect of CDP on the BEL-7402 cancer cells is also investigated upon two-photon illumination at 800 nm. The normalized fluorescence spectra of CDP in tetrahydrofuran (THF) show that two-photon and one-photon spectra have the same distributions and the same emission bands (675 nm). The life-times of two- and one-photon induced fluorescence of this molecule are of the order of 5.0 ns. By comparing the data it is shown that there is some difference between the two lifetimes, but the differ-ence is less than one nanosecond. The two-photon absorption cross section of the molecule is also measured at 800 nm and estimated as about σ'2≈31.5×10-50 cm4·s·photon-1. The results of two-photon photodynamic therapy (TPPDT) tests show that CDP can kill all of the tested cancer cells according to the usual Eosine assessment. Our results indicate that the two-photon-induced photophysical, photochemical and photosensitizing processes of CDP may be basically similar to those of one-photon excitation. These behaviors of the sample suggest that one may find other possible methods to estimate some photosensitizers' effects in details such as their distribution in cells and the reactive targets of the sub-cellular parts of some tumor cells via two-photon excitation techniques.

  14. SU-C-303-05: Photosensitizer Determination for PDT Using Interstitial and Surface Measurements of Fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Kim, M; Finlay, J; Zhu, T [University of Pennsylvania, Philadelphia, PA (United States)

    2015-06-15

    Purpose: Photosensitizer concentration during photodynamic therapy (PDT) is an important parameter for accurate dosimetry. Fluorescence signal can be used as a measure of photosensitizer concentration. Two methods of data acquisition were compared to an ex vivo study both for in vivo and phantom models. Methods: Fluorescence signal of commonly used photosensitizer benzoporphyrin derivative monoacid ring A (BPD) was obtained in phantoms and mouse tumors using an excitation light of 405 nm. Interstitial fluorescence signal was obtained using a side-cut fiber inserted into the tumor tissue of interest. Using a previously developed multi-fiber probe, tumor surface fluorescence measurements were also collected. Signals were calibrated according to optical phantoms with known sensitizer fluorescence. Optical properties for each sample were determined and the influence of different absorption and scattering properties on the fluorescence signals was investigated. Using single value decomposition of the spectra, the sensitizer concentration was determined using the two different measurement geometries. An ex vivo analysis was also performed for tumor samples to determine the sensitizer concentration. Results: The two fluorescence signals obtained from the surface multi-fiber probe and the interstitial measurements were compared and were corresponding for both phantoms and mouse models. The values obtained were comparable to the ex vivo measurements as well. Despite the difference in geometry, the surface probe measurements can still be used as a metric for determining the presence of sensitizer in small volume tumors. Conclusion: The multi-fiber contact probe can be used as a tool to measure fluorescence at the surface of the treatment area for PDT and predict sensitizer concentration throughout the tumor. This is advantageous in that the measurement does not damage any tissue. Future work will include investigating the dependence of these results on intratumor sensitizer

  15. Laser fabrication of three-dimensional CAD scaffolds from photosensitive gelatin for applications in tissue engineering.

    Science.gov (United States)

    Ovsianikov, Aleksandr; Deiwick, Andrea; Van Vlierberghe, Sandra; Dubruel, Peter; Möller, Lena; Dräger, Gerald; Chichkov, Boris

    2011-04-11

    In the present work, 3D CAD scaffolds for tissue engineering applications were developed starting from methacrylamide-modified gelatin (GelMOD) using two-photon polymerization (2PP). The scaffolds were cross-linked employing the biocompatible photoinitiator Irgacure 2959. Because gelatin is derived from collagen (i.e., the main constituent of the ECM), the developed materials mimic the cellular microenvironment from a chemical point of view. In addition, by applying the 2PP technique, structural properties of the cellular microenvironment can also be mimicked. Furthermore, in vitro degradation assays indicated that the enzymatic degradation capability of gelatin is preserved for the methacrylamide-modified derivative. An in depth morphological analysis of the 2PP-fabricated scaffolds demonstrated that the parameters of the CAD model are reproduced with great precision, including the ridge-like surface topography on the order of 1.5 μm. The developed scaffolds showed an excellent stability in culture medium. In a final part of the present work, the suitability of the developed scaffolds for tissue engineering applications was verified. The results indicated that the applied materials are suitable to support porcine mesenchymal stem cell adhesion and subsequent proliferation. Upon applying osteogenic stimulation, the seeded cells differentiated into the anticipated lineage. Energy dispersive X-ray (EDX) analysis showed the induced calcification of the scaffolds. The results clearly indicate that 2PP is capable of manufacturing precisely constructed 3D tissue engineering scaffolds using photosensitive polymers as starting material.

  16. Comparison of two photosensitizers in photodynamic therapy using light pulses in femtosecond regime: an animal study

    Science.gov (United States)

    Grecco, Clóvis; Pratavieira, Sebastião.; Bagnato, Vanderlei; Kurachi, Cristina

    2016-03-01

    Photodynamic therapy is a therapeutic modality for cancer treatment based on the interaction of light with a sensitizer agent and molecular oxygen present into the target cells. The aim of this study is the evaluation of photodynamic therapy using pulsed light source in the femtosecond regime through necrosis induced in healthy rat liver. The induced necrosis profile with CW laser and pulsed laser were evaluated in animal model, which received Photodithazine (chlorine e6 derivative). The light sources used in these studies were a 660 nm CW diode laser and a Ti:Sapphire Regenerative Amplifier laser (1 kHz repetition rate and 100 fs pulse width) associated with an optical parametric amplifier (OPA) to convert to 660 nm. The results were compared with a previous study when was used a hematoporphyrin derivative (Photogem) as a sensitizer. The induced necrosis with Photogen was greater with pulsed laser (2.0 +/- 0.2 mm) in comparison with CW laser (1.0 ± 0.2 mm), while in Photodithazine the induced necrosis with was greater with CW laser (2.9 +/- 0.2 mm) comparing the pulsed laser (2.0 +/- 0.2 mm). These results indicate dependence of PDT mechanisms with photosensitizer and the light regime applied.

  17. Phthalocyanine photodynamic therapy: disparate effects of pharmacologic inhibitors on cutaneous photosensitivity and on tumor regression.

    Science.gov (United States)

    Anderson, C; Hrabovsky, S; McKinley, Y; Tubesing, K; Tang, H P; Dunbar, R; Mukhtar, H; Elmets, C A

    1997-05-01

    The phthalocyanines are promising second-generation photosensitizers that are being evaluated for the photodynamic therapy (PDT) of malignant tumors. In vivo studies with the silicon phthalocyanine Pc 4 have shown that it is highly effective at causing regression of RIF-1 tumors in C3H/HeN mice in PDT protocols. Because cutaneous photosensitivity is the major complication of photosensitizers used for PDT, experiments were performed to evaluate the effect of inhibitors of the inflammatory response (cyproheptadine, dexamethasone, pentoxifylline, and tumor necrosis factor alpha [TNF-alpha] antibodies) on Pc 4-induced cutaneous photosensitivity and tumor regression. The C3H/HeN mice were injected with either Pc 4 or Photofrin and were exposed to 86 J/cm2 of filtered radiation emitted from a solar simulator. Animals were irradiated at 1, 3, 7, 10, 14 and 28 days postinjection. Cutaneous photosensitivity was assessed using the murine ear-swelling response. Cyproheptadine, dexamethasone, pentoxifylline and TNF-alpha antibodies were administered prior to illumination to assess their ability to block Pc 4-induced cutaneous photosensitivity and to evaluate whether such treatment adversely influenced Pc 4 PDT-induced tumor regression. Compared to Photofrin, Pc 4 produced cutaneous photosensitivity that was transient, resolving within 24 h, and that could be elicited for only 10 days after administration. In contrast, Photofrin caused photosensitivity that required 4 days to resolve and could be elicited for at least 1 month after it was administered. The Pc 4-induced cutaneous photosensitivity could be blocked by corticosteroids and an inhibitor of vasoactive amines (cyproheptadine). The TNF-alpha gene transcription was found to increase in keratinocytes following treatment with Pc 4 and light. The anti-TNF-alpha antibodies and pentoxifylline, an inhibitor of cytokine transcription, also prevented cutaneous photosensitivity, implicating TNF-alpha in the pathogenesis of Pc 4

  18. Fundamental study on photodynamic therapy for atrial fibrillation: effect of photosensitization reaction parameters on myocardial necrosis in vitro

    Science.gov (United States)

    Ogawa, Emiyu; Ito, Arisa; Arai, Tsunenori

    2012-03-01

    We studied necrotic cell death effect on myocardial cells with photosensitizer existed outside the cells varying photosensitization reaction parameters widely in vitro. We have developed non-thermal ablator with the application of photosensitization reaction for atrial fibrillation. Since laser irradiation is applied shortly after photosensitizer injection, the photosensitization reaction is induced outside the cells. The interaction for the myocardial cells by the photosensitization reaction is not well understood yet on various photosensitization reaction parameters. Rat myocardial cells were cultured in 96 well plates for 7 days. The photosensitization reaction was applied with talaporfin sodium (NPe6) and the semiconductor laser of 663nm wavelength. The average drug light interval was set 8 mins. The photosensitizer concentration and radiant exposure were varied from 5 to 40 μg/ml and 1.2 to 60 J/cm2, respectively. The well bottom was irradiated by the red laser with irradiance of 293 mW/cm2. The photosensitizer fluorescence was monitored during the photosensitization reaction. Alive cell rate was measured by WST assay after 2 hours from the irradiation. In the case of the photosensitizer concentration of 10 μg/ml, the myocardial cells were almost alive even thought 60 J/cm2 in the radiant exposure was applied. In the 15 μg/ml case, the alive cell rate was almost linear relation to the photosensitizer concentration and radiant exposure. We obtained that the threshold for myocardial cell necrosis on the photosensitizer concentration was around 15 μg/ml with 20 J/cm2 in the radiant exposure. This threshold on the photosensitizer concentration was similar to the reported threshold for cancer therapy.

  19. Microbial control of food-related surfaces: Na-Chlorophyllin-based photosensitization.

    Science.gov (United States)

    Luksiene, Zivile; Paskeviciute, Egle

    2011-10-05

    The aim of this study was to evaluate efficiency of photosensitization as surface sanitation alternative using model systems when food pathogens, their spores and biofilms were attached to the food-related surface (polyolefine). In addition it was important to compare antibacterial efficiency of Na-Chlorophyllin (Na-Chl)-based photosensitization with conventional sanitizers. Obtained results indicate that Bacilluscereus ATCC 12826 and Listeriamonocytogenes ATCC 7644 as well as their thermoresistant strains B.cereus SV90 and L.monocytogenes 56LY were effectively inactivated (7 log) by Na-Chl-based photosensitization in vitro. Inactivation rate of thermoresistant strains was slower. The number of attached to the surface B.cereus ATCC 12826 and L.monocytogenes ATCC 7644 was reduced from 4-4.5 log to 0 log after photosensitization treatment. To achieve adequate inactivation of thermoresistant strains the higher Na-Chl concentration and longer illumination times had to be used. Comparison of different surface decontamination treatments reveal that photosensitization is much more effective against all surface-attached B.cereus and L.monocytogenes strains than washing with water or 200 ppm Na-hypochlorite. It is important to note, that surface-attached B.cereus spores and L.monocytogenes biofilms can be eliminated from it by photosensitization as well. Our data support the idea that Na-Chlorophyllin-based photosensitization has high antibacterial potential which may serve in the future for the development of human and environment friendly, non-thermal surface decontamination technique.

  20. Induction of photosensitivity in sheep with Erodium moschatum (L. L'Hérit

    Directory of Open Access Journals (Sweden)

    J.C. Stroebel

    2002-07-01

    Full Text Available Erodium moschatum is an exotic weed in the southern and southwestern coastal areas of the Western Cape Province (WCP, South Africa. It has been suspected as the cause of photosensitivity in sheep. However, attempts to induce photosensitivity by dosing it to sheep have thus far been unsuccessful. During August 1999, 2 sheep suffering from severe photosensitivity were presented for clinical examination to the Western Cape Provincial Veterinary Laboratory (WCPVL. One sheep was sacrificed for autopsy. Except for skin lesions associated with photosensitivity, no icterus or other lesions were present. Histopathological examination of affected skin revealed epidermal necrosis while the liver had no microscopic lesions. It was therefore concluded that the sheep might have been suffering from primary photosensitivity. The farmfrom which the sheep came, situated in the Malmesbury district, WCP, was visited to determine the source of the photodynamic agent. The flock from which the sheep originated had been grazing in a camp where E. moschatum was growing abundantly and had been heavily grazed. Some remaining Erodium in the camp was collected, pulped and dosed over a period of 7 days to an adult sheep. Another sheep was dosed simultaneously with Erodium growing on the premises of the WCPVL. Both sheep developed mild photosensitivity, which was confirmed by histopathological examination of skin biopsies. It was concluded that E. moschatum can induce photosensitivity (probably the primary type in sheep if ingested in large quantities.

  1. Antibacterial photodynamic therapy for dental caries: evaluation of the photosensitizers used and light source properties.

    Science.gov (United States)

    Nagata, Juliana Yuri; Hioka, Noboru; Kimura, Elza; Batistela, Vagner Roberto; Terada, Raquel Sano Suga; Graciano, Ariane Ximenes; Baesso, Mauro Luciano; Hayacibara, Mitsue Fujimaki

    2012-06-01

    Photodynamic therapy studies have shown promising results for inactivation of microorganisms related to dental caries. A large number of studies have used a variety of protocols, but few studies have analyzed photosensitizers and light source properties to obtain the best PDT dose response for dental caries. This study aims to discuss the photosensitizers and light source properties employed in PDT studies of dental caries. Three questions were formulated to discuss these aspects. The first involves the photosensitizer properties and their performance against Gram positive and Gram negative bacteria. The second discusses the use of light sources in accordance with the dye maximum absorbance to obtain optimal results. The third looks at the relevance of photosensitizer concentration, the possible formation of self-aggregates, and light source effectiveness. This review demonstrated that some groups of photosensitizers may be more effective against either Gram positive or negative bacteria, that the light source must be appropriate for dye maximum absorbance, and that some photosensitizers may have their absorbance modified with their concentration. For the best results of PDT against the main cariogenic bacteria (Streptococcus mutans), a variety of aspects should be taken into account, and among the analyzed photosensitizer, erythrosin seems to be the most appropriate since it acts against this Gram positive bacteria, has a hydrophilic tendency and even at low concentrations may have photodynamic effects. Considering erythrosin, the most appropriate light source should have a maximum emission intensity at a wavelength close to 530 nm, which may be achieved with low cost LEDs.

  2. Investigation of photodynamic therapy optimization for port wine stain using modulation of photosensitizer administration methods.

    Science.gov (United States)

    Wang, Ying; Zuo, Zhaohui; Liao, Xiaohua; Gu, Ying; Qiu, Haixia; Zeng, Jing

    2013-12-01

    To raise photosensitizer concentration level during the photodynamic therapy process, two new methods of photosensitizer administration were investigated. The first method involves the slow intravenous injection of photosensitizer throughout the first 15 min of irradiation, and the second method involves 30 min fomentation before photosensitizer injection and irradiation. The fluorescence spectra of port wine stain skin were monitored and the therapeutic effect correlated index was calculated with a previously published spectral algorithm. Thirty cases were divided into group A (slow injection of photosensitizer during the first 15 min), group B (fomentation), and group C (control group, traditional injection method), with 10 cases in each group. To analyze the effect of these two new methods, the change of therapeutic effect correlated index values of two photodynamic therapy sessions for each patient were calculated, and the photodynamic therapy outcome was compared. The results showed that the change of therapeutic effect correlated index in group A was slightly more remarkable than that in the control group. The change of therapeutic effect correlated index in group B was similar to that in the control group. Slow injection of photosensitizer during photodynamic therapy has a potential to increase photosensitizer concentration level during photodynamic therapy. However, fomentation before photodynamic therapy has no such potential. There is a need for new methods to be attempted.

  3. Natural Dyes as Photosensitizers for Dye-sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Hatem S. El-Ghamri

    2015-10-01

    Full Text Available Dye-sensitized solar cells (DSSCs were assembled using Zinc oxide (ZnO nanoparticles as a photoelectrode and natural dyes extracted from eight natural plants as photosensitizers. The structural properties of the synthesized ZnO nanoparticles were studied using XRD, SEM and TEM characterizations. Photovoltaic parameters such as short circuit current density Jsc, open circuit voltage Voc, fill factor FF, and overall conversion efficiency η for the fabricated cells were determined under 100 mW/cm2 illumination. It was found that the DSSC fabricated with the extracted safflower dye as a sensitizer showed the best performance. Also, its performance increased with increasing the sintering temperature of the semiconductor electrode with highest performance at 400 °C. Moreover, it was found that a semiconductor electrode of 7.5 μm thickness yielded the highest response.

  4. Cell diversity and network dynamics in photosensitive human brain organoids.

    Science.gov (United States)

    Quadrato, Giorgia; Nguyen, Tuan; Macosko, Evan Z; Sherwood, John L; Min Yang, Sung; Berger, Daniel R; Maria, Natalie; Scholvin, Jorg; Goldman, Melissa; Kinney, Justin P; Boyden, Edward S; Lichtman, Jeff W; Williams, Ziv M; McCarroll, Steven A; Arlotta, Paola

    2017-05-04

    In vitro models of the developing brain such as three-dimensional brain organoids offer an unprecedented opportunity to study aspects of human brain development and disease. However, the cells generated within organoids and the extent to which they recapitulate the regional complexity, cellular diversity and circuit functionality of the brain remain undefined. Here we analyse gene expression in over 80,000 individual cells isolated from 31 human brain organoids. We find that organoids can generate a broad diversity of cells, which are related to endogenous classes, including cells from the cerebral cortex and the retina. Organoids could be developed over extended periods (more than 9 months), allowing for the establishment of relatively mature features, including the formation of dendritic spines and spontaneously active neuronal networks. Finally, neuronal activity within organoids could be controlled using light stimulation of photosensitive cells, which may offer a way to probe the functionality of human neuronal circuits using physiological sensory stimuli.

  5. Optical patterning of photosensitive thin film silica mesophases

    Energy Technology Data Exchange (ETDEWEB)

    DOSHI,DHAVAL A.; HUESING,NICOLA K.; LU,MENGCHENG; FAN,HONGYOU; HURD,ALAN J.; BRINKER,C. JEFFREY

    2000-02-09

    Photosensitive films incorporating molecular photoacid generators compartmentalized within a silica-surfactant mesophase were prepared by an evaporation-induced self-assembly process. UV-exposure promoted localized acid-catalyzed siloxane condensation, enabling selective etching of unexposed regions, thereby serving as a resistless technique to prepare patterned mesoporous silica. The authors also demonstrated an optically-defined mesophase transformation (hexagonal {r_arrow} tetragonal) and patterning of refractive index and wetting behavior. Spatial control of structure and function on the macro- and mesoscales is of interest for sensor arrays, nano-reactors, photonic and fluidic devices, and low dielectric constant films. More importantly, it extends the capabilities of conventional lithography from spatially defining the presence or absence of film to spatial control of film structure and function.

  6. Stabilization and encapsulation of photosensitive resveratrol within yeast cell.

    Science.gov (United States)

    Shi, Guorong; Rao, Liqun; Yu, Huazhong; Xiang, Hua; Yang, Hua; Ji, Runa

    2008-02-12

    The photosensitive resveratrol was successfully encapsulated in yeast cells for the first time, as characterized by FT-IR spectra, fluorescence and confocal micrographs of the yeast cells, resveratrol and microcapsules. The release characteristic of the obtained yeast-encapsulated resveratrol in simulated gastric fluid was evaluated, and its storage stability as a powder was investigated at 25 degrees C/75% relative humidity (RH), 25 degrees C/90% RH and 60 degrees C under the laboratory fluorescent lighting conditions (ca. 300 lx) or in the dark. Also, the scavenging capacity of yeast-encapsulated resveratrol on DPPH radical was compared with that of non-encapsulated resveratrol. It could be demonstrated clearly that no chemical changes occurred during the encapsulation. Besides, the DPPH radical-scavenging activity increased after the encapsulation. In addition, the yeast-encapsulated resveratrol exhibited good stability, and its bioavailability was enhanced as a result of increased solubility of resveratrol and sustained releasing.

  7. Degradation of BPB in photocatalysis enhanced by photosensitizer

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The treatment of wastewater containing bromphenol blue (BPB) by WO3/α-Fe2O3 was studied. Reaction mechanism of photocatalysis enhanced by photosensitizer was probed. The relationships between the composition of heterogeneous photocatalyst, the starting concentration of BPB, amount of photocatalyst, pH, amount of H2O2, illumination time and the decoloring rate of BPB were discussed. The results show that the decoloring rate of BPB can reach 99.1% by using WO3/α-Fe2O3 as heterogeneous photocatalyst, with the composition of m(WO3):m(α-Fe2O3 )=3:1, the initial concentration ofBPB = 15mg/L, the amount of catalyst = 0.300 g, pH= 6.3, the amount of H2O2 =0.2 mL, and the illumination time = 6 h.

  8. Analysis of energy saving lamps for use by photosensitive individuals.

    Science.gov (United States)

    Fenton, L; Ferguson, J; Moseley, H

    2012-08-01

    Due to European legislation, the British government has begun the phase out of incandescent bulbs, to be replaced by energy-saving alternatives. The alternatives that are available on the market are Compact Fluorescent Lamps (CFL), Energy-Efficient Halogens (EEH) and Light Emitting Diodes (LED). Whilst previous research has shown that CFLs emit UVC, UVB and UVA, there is conflicting data available on whether double enveloped CFLs are a safer alternative to single enveloped CFLs for individuals suffering from photosensitivity. The emission spectra of 106 single enveloped CFLs and 65 double enveloped CFLs were measured. There were 17 different models of single enveloped CFLs, including lamps from 6 different manufacturers (ranging from 8-20 W) and 9 models of double enveloped CFLs from 6 different manufacturers (7-15 W). In addition, the emission spectra of 53 LEDs and 56 EEHs were also analysed. The LEDs consisted of 8 different models, from 3 manufacturers, spanning between 2.5 and 12 W. There were 11 models of EEH from 6 different manufacturers with wattages ranging from 28-70 W. In order to reduce sample bias, some bulbs were provided by the lighting industry federation and others were purchased randomly from local retailers. The results validate previous research in that considerable variation exists in the UV emitted from CFLs. This variation in UV levels is true, not only within different makes and models but also, surprisingly, within a box of 8 seemingly identical bulbs supplied by a single manufacturer. It was concluded that double enveloped CFLs do reduce the levels of UVC and UVB and therefore are a safer alternative for photosensitive individuals. However, as some double enveloped CFLs and EEHs do emit UVA at levels that provoke a reaction in the skin of UVA sensitive individuals, newly emerging LEDs that have minimal UV levels may provide a safer alternative.

  9. Photochemistry of hypocrellin derivatives under aerobic conditions

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Hypocrellins are a novel type of photosensitizers. A series of new hypocrellin B (HB) derivatives have been synthesized to overcome their limitations, I.e. To improve their red absorption and amphiphilicity. The generation of reactive oxygen species (including superoxide anion radical, hydroxyl radical and singlet oxygen) is investigated in the presence of oxygen. The chemical structures of HB derivatives affect not only the generation efficiencies of superoxide and hydroxyl radicals, but also quantum yields of singlet oxygen.

  10. Distinctive role of activated tumor-associated macrophages in photosensitizer accumulation

    Science.gov (United States)

    Korbelik, Mladen; Krosl, Gorazd

    1995-05-01

    Cells dissociated from tumors (carcinomas and sarcomas) growing subcutaneously in mice that have been administered Photofrin or other photosensitizers were analyzed by flow cytometry. Monoclonal antibodies were used for identification of major cellular populations contained in these tumors. The results demonstrate that a subpopulation of tumor-associated macrophages (TAMs) is unique among tumor cell populations in that it excels in the accumulation of very high levels of photosensitizers. These macrophages showed an increased expression of interleukin 2 receptor, which is indicative of their activated state. since macrophages were reported to concentrate in the periphery of human neoplasms, it is suggested that activates TAMs are the determinants of tumor-localized photosensitizer fluorescence.

  11. Photosensitized cleavage of some olefins as potential linkers to be used in drug delivery

    Science.gov (United States)

    Dinache, Andra; Smarandache, Adriana; Simon, Agota; Nastasa, Viorel; Tozar, Tatiana; Pascu, Alexandru; Enescu, Mironel; Khatyr, Abderrahim; Sima, Felix; Pascu, Mihail-Lucian; Staicu, Angela

    2017-09-01

    A study of photosensitized cleavage of different olefins as potential linkers for drug carrier complexes is reported. The role of singlet oxygen and the kinetic rates for light induced reactions were estimated by time-resolved measurements of singlet oxygen phosphorescence (at 1270 nm) obtained via 532 nm pulse laser excitation of a photosensitizer. The mixture of each studied olefin with verteporfin (used as photosensitizer) were exposed to low energy visible radiation. The rate constants for singlet oxygen quenching by studied olefins were determined. The irradiated solutions were investigated by FTIR spectroscopy and potential photoproducts were suggested. The experimental results were compared with simulations made by DFT method.

  12. Study on the photosensitizing effects and tumor-photobiological activity of chlorin e6 amide derivatives%二氢卟吩e6酰胺衍生物的光敏效应及肿瘤光生物活性

    Institute of Scientific and Technical Information of China (English)

    章玲; 姚建忠; 刘建飞; 王小燕; 张万年; 周有骏; 朱驹; 吕加国

    2002-01-01

    目的寻找新型的光动力治疗肿瘤新药.方法以蚕沙叶绿素粗提物为原料合成4种二氢卟吩e6酰胺衍生物(Ⅰ1~Ⅰ4),并测定其光敏效应和肿瘤光生物活性.结果Ⅰ1~Ⅰ4表现出较强的光敏效应,且强于参比药物血卟啉衍生物(hematoporphyrin derivative, HPD);Ⅰ1~Ⅰ4对小鼠S180肉瘤有较好的光动力损伤作用,其中Ⅰ3的光动力损伤作用要好于HPD.结论提示二氢卟吩e6酰胺衍生物是一类具有发展前途的光动力抗肿瘤新药.

  13. Photodegradation of environmental mutagens by visible irradiation in the presence of xanthene dyes as photosensitizers.

    Science.gov (United States)

    Odo, Junichi; Torimoto, Sei-ichi; Nakanishi, Suguru; Niitani, Tomoya; Aoki, Hiroyuki; Inoguchi, Masahiko; Yamasaki, Yu

    2012-01-01

    The photodegradation of environmental mutagens, such as 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC), and 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), was investigated by visible irradiation in the presence of xanthene dyes as photosensitizers. Although the environmental mutagens themselves were very stable during visible irradiation under the conditions in this study, they were effectively photodegraded in the presence of the xanthene dyes (erythrosine, rose bengal, and phloxine). Moreover, photodegradation of the mutagens was further enhanced for xanthene dyes loaded onto a water-soluble diethylaminoethyl (DEAE)-dextran anion-exchanger via ionic interactions (xanthene-dyeDEX). Photodegradation was inhibited by O2 removal from the reaction solution. In ESR spin-trapping experiments using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a trapping reagent, signals characteristic of DMPO-•OH (hydroxyl radical) were observed in the presence of xanthene-dyeDEX. These results suggest that reactive oxygen species derived from O2, such as singlet molecular oxygen (•1O2) and/or •OH, were active participants in photodegradation of the mutagens in the presence of xanthene dyes or xanthene-dyeDEX.

  14. Prospective study of luminous radiation associated technology photosensitive compounds for treatment of diseases

    Science.gov (United States)

    Pires-Santos, Gustavo M.; de Oliveira, Susana C. P. S.; Monteiro, Juliana S. C.; Sampaio, Fernando José P.; Brugnera, Aldo; Zanin, Fátima Antônia A.; Almeida, Paulo; Pinheiro, Antônio L. B.

    2015-03-01

    Prospective studies are based on the analysis of patent documents and aims to assess the both technological history and development providing innovation opportunities. This study was a technological prospection mapping aiming to identify breakthrough in PDT and the new possibilities of the technology. Therefore, research in the bank patent 'Spacenet Patent Search' was performed using determinants descriptors associated with the theme: 'A61K41', 'A61N5 / 06'. Were analyzed in this study 326 documents. In evaluating these patents, it was possible to observe an increase in the number of deposits over time, with peak between 1990 and 2000. The highest number of inventors of this area are part of the private sector and the US appear as main producer of technology. It was also observed that blue light, porphyrins and their derivatives are the main topics. It may be concluded that PDT still offers a large opportunity for growth as several wavelengths, and photosensitizers that may be used in the technique.

  15. Photosensitized oxidation and inactivation of pyocyanin, a virulence factor of Pseudomonas aeruginosa.

    Science.gov (United States)

    Reszka, Krzysztof J; Denning, Gerene M; Britigan, Bradley E

    2006-01-01

    Pyocyanin (PyO-) (1-hydroxy-5-methylphenazine) is a cytotoxic compound secreted by Pseudomonas aeruginosa, an omnipresent bacterium and a human pathogen. We report that visible light illumination in the presence of rose bengal, or riboflavin, in aerated solutions (pH 7.0-7.2) induces irreversible loss of the pigment's characteristic absorption band at 690 nm, indicating its oxidation. This photobleaching was paralleled by generation of a multiline Electron Paramagnetic Resonance (EPR) spectrum attributed to a PyO(-)-derived radical. The reaction was dependent on the presence of air, sensitizers and light, was inhibited by sodium azide and was unaffected by ethanol. This suggests that PyO- was oxidized largely via singlet oxygen and that hydroxyl radicals were not involved. The photochemically modified pigment was less efficient in oxidizing NAD(P)H and generated less superoxide (by approximately 50%) than the intact PyO-, indicating its partial inactivation. 1-Methoxy-5-methylphenazine, a PyO- analog in which the -O- moiety was replaced by the methoxy group (-OMe), was resistant to oxidation, suggesting that oxidation of PyO- involves its phenolate moiety. These results also suggest that photosensitization could be a potentially useful method for inactivation of PyO- and, possibly, detoxification of superficial wounds (skin, eye) infected with P. aeruginosa.

  16. 3-D photo-patterning of refractive index structures in photosensitive thin film materials

    Science.gov (United States)

    Potter, Jr., Barrett George; Potter, Kelly Simmons

    2002-01-01

    A method of making a three-dimensional refractive index structure in a photosensitive material using photo-patterning. The wavelengths at which a photosensitive material exhibits a change in refractive index upon exposure to optical radiation is first determined and then a portion of the surface of the photosensitive material is optically irradiated at a wavelength at which the photosensitive material exhibits a change in refractive index using a designed illumination system to produce a three-dimensional refractive index structure. The illumination system can be a micro-lenslet array, a macroscopic refractive lens array, or a binary optic phase mask. The method is a single-step, direct-write procedure to produce a designed refractive index structure.

  17. Getting it right: 3D cell cultures for the assessment of photosensitizers for photodynamic therapy

    OpenAIRE

    SENGE, MATHIAS

    2015-01-01

    PUBLISHED Core quote “Cancer drug screening is rapidly moving towards the use of 3D cell models. The added complexity of PDT action makes this a conditio sine qua non for the screening of new photosensitizers.”

  18. Phthalocyanine-Biomolecule Conjugated Photosensitizers for Targeted Photodynamic Therapy and Imaging.

    Science.gov (United States)

    Iqbal, Zafar; Chen, Jincan; Chen, Zhuo; Huang, Mingdong

    2015-01-01

    Photodynamic therapy (PDT) is now in clinical practice in many European and American countries as a minimally invasive therapeutic technique to treat oncologic malignancies and other nononcologic conditions. Phthalocyanines (Pcs) are gathering importance as effective photosensitizers in targeted PDT and imaging of tumors. The possibility of modification around the Pc macrocycle led the researchers to the synthesis of a diversity of photosensitizers with varied cell specificity, cellular internalization and localization, photodynamic cytotoxicity and excretion. Cellular targeting is the primary aspect of an ideal photosensitizer for targeting PDT. Therefore, Pcs have been structurally modified with a variety of biomolecules capable of recognizing the specific lesions. This review emphasizes the photocytotoxicity and the cellular uptakes of phthalocyanine photosensitizers conjugated with biomolecules including carbohydrates, nucleotides and protein constituents such as amino acids and peptides. In addition, the role of the Pc-biomolecule conjugates in imaging and antimicrobial chemotherapy has been discussed.

  19. White matter microstructural changes of thalamocortical networks in photosensitivity and idiopathic generalized epilepsy

    DEFF Research Database (Denmark)

    Groppa, Sergiu; Moeller, Friederike; Siebner, Hartwig

    2012-01-01

    Photosensitivity or photoparoxysmal response (PPR) is an electroencephalography trait that is highly associated with idiopathic generalized epilepsies (IGEs) and characterized by changes in cortical excitability in response to photic stimulation. Studying functional and structural changes of PPR ...

  20. Plasmonic Nanoparticle-based Hybrid Photosensitizers with Broadened Excitation Profile for Photodynamic Therapy of Cancer Cells

    Science.gov (United States)

    Wang, Peng; Tang, Hong; Zhang, Peng

    2016-10-01

    Photodynamic therapy combining nanotechnology has shown great potential with improved therapeutic efficacy and fewer side effects. Ideal photosensitizers for cancer treatment should both have good singlet oxygen production capability and be excitable by light illuminations with deep tissue penetration. Here we report a type of hybrid photosensitizers consisting of plasmonic silver nanoparticles and photosensitizing molecules, where strong resonance coupling between the two leads to a broadened excitation profile and exceptionally high singlet oxygen production under both visible light and infrared light excitations. Our results indicate that the hybrid photosensitizers display low cytotoxicity without light illumination yet highly enhanced photodynamic inhibition efficacy against Hela cells under a broad spectrum of light illuminations including the near-infrared light, which has great implication in photodynamic therapy of deep-tissue cancers.

  1. Direct oligonucleotide-photosensitizer conjugates for photochemical delivery of antisense oligonucleotides.

    Science.gov (United States)

    Yuan, Ahu; Laing, Brian; Hu, Yiqiao; Ming, Xin

    2015-04-18

    Activation of photosensitizers in endosomes enables release of therapeutic macromolecules into the cytosol of the target cells for pharmacological actions. In this study, we demonstrate that direct conjugation of photosensitizers to oligonucleotides (ONs) allows spatial and temporal co-localization of the two modalities in the target cells, and thus leads to superior functional delivery of ONs. Further, light-activated delivery of an anticancer ON caused cancer cell killing via modulation of an oncogene and photodynamic therapy.

  2. Modifying excitation light dose of novel photosensitizer PVP-Hypericin for photodynamic diagnosis and therapy

    OpenAIRE

    Penjweini, Rozhin; Loew, Hans G.; Eisenbauer, Maria; Kratky, Karl W.

    2013-01-01

    Conventional photodynamic diagnosis (PDD) and therapy (PDT) makes use of photosensitizers that are excited by continuous light irradiation of specific wavelengths. In the case of PDT, the overdose of continuous excitation may lead to an expansion of necrosis in cancer cells or morbidity in healthy surroundings. The present study involves 5-h fluorescence imaging of living human lung epithelial carcinoma cells (A549) in the presence of a novel photosensitizer, PVP-Hypericin (PVP: polyvinylpyrr...

  3. Astaxanthin protecting membrane integrity against photosensitized oxidation through synergism with other carotenoids

    DEFF Research Database (Denmark)

    Du, Hui-Hui; Liang, Ran; Han, Rui-Min

    2015-01-01

    Incorporation of astaxanthin or zeaxanthin in giant unilamellar vesicles (GUVs) of phosphatidylcholine resulted in a longer lag phase than incorporation of β-carotene or lycopene for the onset of budding induced by chlorophyll a photosensitization and quantified by a dimensionless entropy paramet...... a in the membrane interior in parallel with scavenging of superoxide radicals by astaxanthin anchored in the surface may explain the synergism between carotenoids involving both type I and type II photosensitization by chlorophyll a....

  4. Theoretical Study on the Photosensitizer Mechanism of Phenalenone in Aqueous and Lipid Media.

    Science.gov (United States)

    Espinoza, César; Trigos, Ángel; Medina, Manuel E

    2016-08-11

    The photosensitizer ability of phenalenone was studied in aqueous and lipid media through the single electron transfer reactions, employing the density functional theory. Although phenalenone is a well-known photosensitizer and is widely used as an (1)O2 reference sensitizer, little is known about the reaction mechanism involved. In this study we carried out a single electron transfer reaction between the basal, excited, oxidized and reduced state of phenalenone with oxygen molecules such as (3)O2 and O2(•-). In aqueous media the photosensitizer capacity of phenalenone was measured through both type I and type II mechanisms. In lipid media the photosensitizer ability of phenalenone was attributed to the type II mechanism. The results indicated that the photosensitizer ability of phenalenone shows a heavy reliance on the media where the reaction occurs whether this is an aqueous or lipid media. Finally, this study supports the idea about that electron transfer reactions can be used to study the photosensitizer ability of molecules.

  5. Recombinant modular transporters on the basis of epidermal growth factor for targeted intracellular delivery of photosensitizers

    Science.gov (United States)

    Gilyazova, Dinara G.; Rosenkranz, Andrey A.; Gulak, Pavel V.; Lunin, Vladimir G.; Sergienko, Olga V.; Grin, Mikhail A.; Mironov, Andrey F.; Rubin, Andrey B.; Sobolev, Alexander S.

    2005-08-01

    The search for new pharmaceuticals has raised interest in locally-acting drugs which act over short distances within the cell, and for which different cell compartments have different sensitivities. Thus, photosensitizers used in anti-cancer therapy should be transported to the most sensitive subcellular compartments where their action is most pronounced. Earlier, we described the effects of bacterially expressed modular recombinant transporters for photosensitizers comprising a-melanocyte-stimulating hormone as an internalizable, cell-specific ligand, an optimized nuclear localization sequence, an Escherichia coli hemoglobin-like protein as a carrier, and an endosomolytic amphipathic polypeptide. These transporters delivered photosensitizers into the murine melanoma cells nuclei to result in cytotoxic effects 2 orders of magnitude greater than those of nonmodified photosensitizers. Here we describe new transporters possessing the same modules except for a ligand that is replaced with epidermal growth factor specific for other cancer cell types. The new transporter modules retained their functional activities within the chimera, this transporter delivered photosensitizers into the human carcinoma cells nuclei to result in photocytotoxic effects almost 3 orders of magnitude greater than those of nonmodified photosensitizers. The obtained results show that ligand modules of such transporters are interchangeable, meaning that they can be tailored for particular applications.

  6. A novel automated instrument designed to determine photosensitivity thresholds (Conference Presentation)

    Science.gov (United States)

    Aguilar, Mariela C.; Gonzalez, Alex; Rowaan, Cornelis; De Freitas, Carolina; Rosa, Potyra R.; Alawa, Karam; Lam, Byron L.; Parel, Jean-Marie A.

    2016-03-01

    As there is no clinically available instrument to systematically and reliably determine the photosensitivity thresholds of patients with dry eyes, blepharospasms, migraines, traumatic brain injuries, and genetic disorders such as Achromatopsia, retinitis pigmentosa and other retinal dysfunctions, a computer-controlled optoelectronics system was designed. The BPEI Photosensitivity System provides a light stimuli emitted from a bi-cupola concave, 210 white LED array with varying intensity ranging from 1 to 32,000 lux. The system can either utilize a normal or an enhanced testing mode for subjects with low light tolerance. The automated instrument adjusts the intensity of each light stimulus. The subject is instructed to indicate discomfort by pressing a hand-held button. Reliability of the responses is tracked during the test. The photosensitivity threshold is then calculated after 10 response reversals. In a preliminary study, we demonstrated that subjects suffering from Achromatopsia experienced lower photosensitivity thresholds than normal subjects. Hence, the system can safely and reliably determine the photosensitivity thresholds of healthy and light sensitive subjects by detecting and quantifying the individual differences. Future studies will be performed with this system to determine the photosensitivity threshold differences between normal subjects and subjects suffering from other conditions that affect light sensitivity.

  7. Engineering of ruthenium(II) oxy- and carboxyamido-quinolate non-innocent ligand photosensitizers for dye sensitized solar cells.

    Science.gov (United States)

    Ngo, Ken Tue; Lee, Nicholas A; Pinnace, Sashari; Rochford, Jonathan

    2017-02-11

    An alternative approach towards the replacement of the isothiocyantate ligands of the N3 photosensitizer with light-harvesting bidentate ligands is investigated for application in dye-sensitized solar cells. An in depth theoretical analysis has been applied to inform on the optical and redox properties of four non-innocent ligand platforms which is corroborated with experiment. Taking advantage of the 5- and 7-positions of 8-oxyquinolate, or the carboxyaryl ring system of the N-arylcarboxy-8-amidoquinolate ligand, fluorinated aryl substituents are demonstrated as an effective means to tune complex redox potentials and light harvesting properties. The non-innocent character derived from covalent mixing of both the central metal d(pi) and ligand-(pi) manifolds generates hybrid metal-ligand frontier orbitals that play a major role in contributing to the redox properties and visible electronic transitions, and promote an improved power conversion efficiency in a Ru non-innocent ligand sensitized DSSC device.

  8. Singlet oxygen generation using a porous monolithic polymer supported photosensitizer: potential application to the photodynamic destruction of melanoma cells.

    Science.gov (United States)

    Burguete, M Isabel; Galindo, Francisco; Gavara, Raquel; Luis, Santiago V; Moreno, Miguel; Thomas, Paul; Russell, David A

    2009-01-01

    Photogeneration of singlet oxygen (1O2) by rose bengal is improved through the use of a porous monolithic polymer (PMP) as a support, as compared to a classic gel-type resin matrix. This type of monolithic polymeric matrix can be made at a multigram scale in quantitative yields enabling the preparation of large amounts of supported photosensitizer at low cost. The singlet oxygen induced oxidation of 9,10-diphenylanthracene has been used as a benchmark reaction, and a comparative study using rose bengal in solution, entrapped within gel-type derived polymer and entrapped within a porous monolithic polymer (PMP) has been performed. The enhanced photoreactivity of the PMP-rose bengal conjugates has been utilised for the successful photodynamic therapy (PDT) of melanoma cells.

  9. A biosolar cell incorporating a TiO{sub 2} nanocrystalline thin-film electrode with chlorophyllin as the photosensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, T.T.C; Ho, K.C. [National Taiwan Univ., Taipei, Taiwan (China). Dept. of Chemical Engineering

    2006-07-01

    The exploration for new, sustainable energy technologies, such as solar energy, has been driven by the depletion of fossil fuels and the prevention of pollution. A new type of photovoltaic cell known as the dye-sensitized solar cell (DSSC) was discovered in 1990. Studies have shown that the DSSC adsorbs dye on the nanocrystalline TiO{sub 2} surface area to absorb visible light with a cell efficiency of 11 per cent. Ruthenium complexes are commonly used as the photosensitizers to achieve high cell efficiencies. However, due to the environmental concerns regarding the use of heavy metal, derivatives of chlorophyll have been suggested as alternatives. In this study, the phytyl ester and the cyclopentanone of chlorophyll have been saponified and opened, respectively. Chlorophyllin, a derivative of chlorophyll, was absorbed on a TiO{sub 2} film electrode to act as the photosensitizer in a dye-sensitized biosolar cell. Chlorophyllin was generated with the formation of two additional carboxyl groups which are needed for anchoring the dye onto the surface of a TiO{sub 2} electrode to ensure good cell performance. The cell yielded an open-circuit voltage of 0.44 V and a short-circuit current density of 420 {mu}A/cm{sup 2}, with a calculated fill factor of 0.61. The overall energy conversion efficiency of the cell was approximately 0.11 to 0.13 per cent. Although chlorophyllin had good absorption properties in the visible range, the cell efficiency of a DSSC containing chlorophyllin was low. The efficiency of the biosolar cell first decreased, but achieved a stable value within a short period of time. 5 refs., 3 figs.

  10. Polymeric micelles encapsulating photosensitizer: structure/photodynamic therapy efficiency relation.

    Science.gov (United States)

    Gibot, Laure; Lemelle, Arnaud; Till, Ugo; Moukarzel, Béatrice; Mingotaud, Anne-Françoise; Pimienta, Véronique; Saint-Aguet, Pascale; Rols, Marie-Pierre; Gaucher, Mireille; Violleau, Frédéric; Chassenieux, Christophe; Vicendo, Patricia

    2014-04-14

    Various polymeric micelles were formed from amphiphilic block copolymers, namely, poly(ethyleneoxide-b-ε-caprolactone), poly(ethyleneoxide-b-d,l-lactide), and poly(ethyleneoxide-b-styrene). The micelles were characterized by static and dynamic light scattering, electron microscopy, and asymmetrical flow field-flow fractionation. They all displayed a similar size close to 20 nm. The influence of the chemical structure of the block copolymers on the stability upon dilution of the polymeric micelles was investigated to assess their relevance as carriers for nanomedicine. In the same manner, the stability upon aging was assessed by FRET experiments under various experimental conditions (alone or in the presence of blood proteins). In all cases, a good stability over 48 h for all systems was encountered, with PDLLA copolymer-based systems being the first to release their load slowly. The cytotoxicity and photocytotoxicity of the carriers were examined with or without their load. Lastly, the photodynamic activity was assessed in the presence of pheophorbide a as photosensitizer on 2D and 3D tumor cell culture models, which revealed activity differences between the 2D and 3D systems.

  11. Femtosecond laser collagen cross-linking without traditional photosensitizers

    Science.gov (United States)

    Guo, Yizang; Wang, Chao; Celi, Nicola; Vukelic, Sinisa

    2015-03-01

    Collagen cross-linking in cornea has the capability of enhancing its mechanical properties and thereby providing an alternative treatment for eye diseases such as keratoconus. Currently, riboflavin assisted UVA light irradiation is a method of choice for cross-link induction in eyes. However, ultrafast pulsed laser interactions may be a powerful alternative enabling in-depth treatment while simultaneously diminishing harmful side effects such as, keratocyte apoptosis. In this study, femtosecond laser is utilized for treatment of bovine cornea slices. It is hypothesized that nonlinear absorption of femtosecond laser pulses plays a major role in the maturation of immature cross-links and the promotion of their growth. Targeted irradiation with tightly focused laser pulses allows for the absence of a photosensitizing agent. Inflation test was conducted on half treated porcine cornea to identify the changes of mechanical properties due to laser treatment. Raman spectroscopy was utilized to study subtle changes in the chemical composition of treated cornea. The effects of treatment are analyzed by observing shifts in Amide I and Amide III bands, which suggest deformation of the collagen structure in cornea due to presence of newly formed cross-links.

  12. Natural dyes as photosensitizers for dye-sensitized solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Sancun; Wu, Jihuai; Huang, Yunfang; Lin, Jianming [Institute of Materials Physical Chemistry, Huaqiao University, Quanzhou, Fujian 362021 (China)

    2006-02-15

    The dye-sensitized solar cells (DSC) were assembled by using natural dyes extracted from black rice, capsicum, erythrina variegata flower, rosa xanthina, and kelp as sensitizers. The I{sub SC} from 1.142mA to 0.225mA, the V{sub OC} from 0.551V to 0.412V, the fill factor from 0.52 to 0.63, and P{sub max} from 58{mu}W to 327{mu}W were obtained from the DSC sensitized with natural dye extracts. In the extracts of natural fruit, leaves and flower chosen, the black rice extract performed the best photosensitized effect, which was due to the better interaction between the carbonyl and hydroxyl groups of anthocyanin molecule on black rice extract and the surface of TiO{sub 2} porous film. The blue-shift of absorption wavelength of the black rice extract in ethanol solution on TiO{sub 2} film and the blue-shift phenomenon from absorption spectrum to photoaction spectrum of DSC sensitized with black rice extract are discussed in the paper. Because of the simple preparation technique, widely available and low cheap cost natural dye as an alternative sensitizer for dye-sensitized solar cell is promising. (author)

  13. Molecular mechanics study on conformation of perylene-quinonoid photosensitizers

    Institute of Scientific and Technical Information of China (English)

    张红雨; 张志义

    1997-01-01

    Using molecular mechanics method,values of the heat of formation (HF) of different conformations,of perylenequinonoid photosensitizes hypocrellin A (HA) and hypocrellin B (HB) were calculated and the variance of HF after phenolic protons’ dissociation were calculated as well The following was found:(i) The HF values of lour conformational isomers of HA and HB are similar to each other,so the four isomcrs can transform to each other room temperature,(ii) There exists the difference between the ability of dissociation of phenolic protons of HA and that of HB,the former is higher than the latter (iii) There exist two intramolecular hydrogen bonds in HA and HB The bond energy is approximately 8 kJ/mol and the energy of conformation Ⅰ is lower than that of conformationⅡ The bond energy of HA is lower than that of HB.(iv) There exists a low energy snot when phenolic hydroxyl bond twists 180° from the position where hydrogen bond is formed,which suggests that this kind of conformation probably exists,(v) Th

  14. Interaction of photosensitive surfactant with DNA and poly acrylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Zakrevskyy, Yuriy, E-mail: yuriy.zakrevskyy@fh-koeln.de; Paasche, Jens; Lomadze, Nino; Santer, Svetlana, E-mail: santer@uni-potsdam.de [Experimental Physics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam (Germany); Cywinski, Piotr; Cywinska, Magdalena; Reich, Oliver; Löhmannsröben, Hans-Gerd [Physical Chemistry, Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam (Germany)

    2014-01-28

    In this paper, we investigate interactions and phase transitions in polyelectrolyte-surfactant complexes formed between a cationic azobenzene-containing surfactant and two types of polyelectrolytes: natural (DNA) or synthetic (PAA: poly acrylic acid). The construction of a phase diagram allowed distancing between four major phases: extended coil conformation, colloidally stable compacted globules, colloidal instability range, and surfactant-stabilized compact state. Investigation on the complexes’ properties in different phases and under irradiation with UV light provides information about the role of the surfactant's hydrophobic trans isomers both in the formation and destruction of DNA and PAA globules as well as in their colloidal stabilization. The trans isomer shows much stronger affinity to the polyelectrolytes than the hydrophilic cis counterpart. There is no need for complete compensation of the polyelectrolyte charges to reach the complete compaction. On contrary to the findings previously reported in the literature, we demonstrate – for the first time – complete polyelectrolyte compaction which occurs already at 20% of DNA (and at 50% of PAA) charge compensation. The trans isomer plays the main role in the compaction. The aggregation between azobenzene units in the photosensitive surfactant is a driving force of this process. The decompaction can be realized during UV light irradiation and is strongly influenced by the interplay between surfactant-surfactant and surfactant-DNA interactions in the compacted globules.

  15. Interaction of photosensitive surfactant with DNA and poly acrylic acid

    Science.gov (United States)

    Zakrevskyy, Yuriy; Cywinski, Piotr; Cywinska, Magdalena; Paasche, Jens; Lomadze, Nino; Reich, Oliver; Löhmannsröben, Hans-Gerd; Santer, Svetlana

    2014-01-01

    In this paper, we investigate interactions and phase transitions in polyelectrolyte-surfactant complexes formed between a cationic azobenzene-containing surfactant and two types of polyelectrolytes: natural (DNA) or synthetic (PAA: poly acrylic acid). The construction of a phase diagram allowed distancing between four major phases: extended coil conformation, colloidally stable compacted globules, colloidal instability range, and surfactant-stabilized compact state. Investigation on the complexes' properties in different phases and under irradiation with UV light provides information about the role of the surfactant's hydrophobic trans isomers both in the formation and destruction of DNA and PAA globules as well as in their colloidal stabilization. The trans isomer shows much stronger affinity to the polyelectrolytes than the hydrophilic cis counterpart. There is no need for complete compensation of the polyelectrolyte charges to reach the complete compaction. On contrary to the findings previously reported in the literature, we demonstrate - for the first time - complete polyelectrolyte compaction which occurs already at 20% of DNA (and at 50% of PAA) charge compensation. The trans isomer plays the main role in the compaction. The aggregation between azobenzene units in the photosensitive surfactant is a driving force of this process. The decompaction can be realized during UV light irradiation and is strongly influenced by the interplay between surfactant-surfactant and surfactant-DNA interactions in the compacted globules.

  16. Monitoring photosensitizer uptake using two photon fluorescence lifetime imaging microscopy.

    Science.gov (United States)

    Yeh, Shu-Chi Allison; Diamond, Kevin R; Patterson, Michael S; Nie, Zhaojun; Hayward, Joseph E; Fang, Qiyin

    2012-01-01

    Photodynamic Therapy (PDT) provides an opportunity for treatment of various invasive tumors by the use of a cancer targeting photosensitizing agent and light of specific wavelengths. However, real-time monitoring of drug localization is desirable because the induction of the phototoxic effect relies on interplay between the dosage of localized drug and light. Fluorescence emission in PDT may be used to monitor the uptake process but fluorescence intensity is subject to variability due to scattering and absorption; the addition of fluorescence lifetime may be beneficial to probe site-specific drug-molecular interactions and cell damage. We investigated the fluorescence lifetime changes of Photofrin(®) at various intracellular components in the Mat-LyLu (MLL) cell line. The fluorescence decays were analyzed using a bi-exponential model, followed by segmentation analysis of lifetime parameters. When Photofrin(®) was localized at the cell membrane, the slow lifetime component was found to be significantly shorter (4.3 ± 0.5 ns) compared to those at other locations (cytoplasm: 7.3 ± 0.3 ns; mitochondria: 7.0 ± 0.2 ns, p < 0.05).

  17. Monitoring Photosensitizer Uptake Using Two Photon Fluorescence Lifetime Imaging Microscopy

    Directory of Open Access Journals (Sweden)

    Shu-Chi Allison Yeh, Kevin R. Diamond, Michael S. Patterson, Zhaojun Nie, Joseph E. Hayward, Qiyin Fang

    2012-01-01

    Full Text Available Photodynamic Therapy (PDT provides an opportunity for treatment of various invasive tumors by the use of a cancer targeting photosensitizing agent and light of specific wavelengths. However, real-time monitoring of drug localization is desirable because the induction of the phototoxic effect relies on interplay between the dosage of localized drug and light. Fluorescence emission in PDT may be used to monitor the uptake process but fluorescence intensity is subject to variability due to scattering and absorption; the addition of fluorescence lifetime may be beneficial to probe site-specific drug-molecular interactions and cell damage. We investigated the fluorescence lifetime changes of Photofrin® at various intracellular components in the Mat-LyLu (MLL cell line. The fluorescence decays were analyzed using a bi-exponential model, followed by segmentation analysis of lifetime parameters. When Photofrin® was localized at the cell membrane, the slow lifetime component was found to be significantly shorter (4.3 ± 0.5 ns compared to those at other locations (cytoplasm: 7.3 ± 0.3 ns; mitochondria: 7.0 ± 0.2 ns, p < 0.05.

  18. Photophysical and photochemical properties of Bauhinia megalandra (Caesalpinaceae) extracts as new PDT photosensitizer

    Science.gov (United States)

    Vargas Tovar, Franklin R.; Rivas, C.; Estrada, O.; Marcano O., Aristides A.; Echevarria, Lorenzo; Diaz, Yrene; Alexander, I.; Rodriguez, L.; Padron, L.; Rivera, I. R.

    2004-10-01

    Recently new photosensitizers, chlorophyll "a and b" derivatives, for photodynamic therapy (PDT) have been presented. It already passed complete pre-clinical investigations. This prompted us to carry out an extensive study of photophysical properties of chlorine derivatives, important both for optimization of their clinic applications and for study of mechanisms of chlorine PDT&. The fresh leaves of Bauhinia megalandra (Caesalpinaceae) were extracted with methanol by percolation, and re-extract with a mixture of methanol-water (1:1), the insoluble fraction was then separated by column chromatography [RP18/hexane-ethylacetate (9:1)] to obtain four fractions named 1 to 4. These compounds were identified by NMR data. We found that 3 and 4 efficiently generates singlet oxygen when irradiated with visible light. Detection of the singlet oxygen was fulfilled by its reaction with histidine and detected by bleaching p-nitrosodimethylaniline under 440 nm irradiation. The quantum yields of singlet oxygen determined by us were 0.088 (1), 0.151 (2), 0.219 (3) and 0.301 (4). We measured absorption and fluorescence spectra of compounds 1 to 4 (Mg-chlorophyll-a, Pheophytin, Mg-chlorophyll-b and chlorophyll-b respectively) in different media and in aqueous solutions of human serum albumin. The association constant of the compounds 1, 2, 3 and 4 in the presence of HSA were estimated. The binding and quenching studies suggest that only 1 and 3 may serve as a useful fluorescence probe for structure/function studies of different chlorophyll binding proteins. No photoinduced binding was observed after irradiation by all the studied compounds in presence of human serum albumin.

  19. Laser microscope-spectrum analyzer for studying intracellular accumulation of near infrared emitting photosensitizers in vitro

    Directory of Open Access Journals (Sweden)

    Yu. S. Maklygina

    2015-01-01

    Full Text Available Measuring system based on the binocular microscope for analysis of intracellular accumulation of infrared IR photosenstizers allowing to obtain graphic data about state of analyzed objects, location of fluorescence foci and to obtain details of spectral profile of fluorescence emission centers in IR spectral region was developed. According to image of fluorescence signal distribution the location of photosensitizer accumulation in the cell may be detected accurately and the spectrum of fluorescence signal of near IR-range in the targeted point may be obtained. The developed system is quite comprehensive because there is an opportunity to choose technical parameters, operating modes, measuring methods and analysis. The advantage of the developed microscope-spectrum analyzer is an opportunity to focus emission and create high power intensity on the irradiated area by means of laser source with small-angle beam spreading, all this allow to perform ultra-precise operations with cells. Particularly, tunable size of the diaphragm opening in the far field allows to register fluorescence signal on certain cell organoids. By means of developed system the studies of accumulation of the new bacteriochlorine photosensitizers on HeLa cell line were performed. The system allowed to register accumulation of cancer cells with definite sites of selectively accumulated photosensitizer. The sites of fluorescence were the centers of accumulation of bacteriochlorine photosensitizer, this suggests that studied photosensitizer has a tendency for local accumulation in cellular organoids. The authors suggested that the developed system allowed to perform the effective and rapid screening of new photosensitizers, particularly IR bacteriochlorine photosensitizers

  20. Site-specific conjugation of single domain antibodies to liposomes enhances photosensitizer uptake and photodynamic therapy efficacy

    Science.gov (United States)

    Broekgaarden, M.; van Vught, R.; Oliveira, S.; Roovers, R. C.; van Bergen En Henegouwen, P. M. P.; Pieters, R. J.; van Gulik, T. M.; Breukink, E.; Heger, M.

    2016-03-01

    Photodynamic therapy for therapy-resistant cancers will greatly benefit from targeted delivery of tumor photosensitizing agents. In this study, a strategy for the site-specific conjugation of single domain antibodies onto liposomes containing the photosensitizer zinc phthalocyanine was developed and tested.Photodynamic therapy for therapy-resistant cancers will greatly benefit from targeted delivery of tumor photosensitizing agents. In this study, a strategy for the site-specific conjugation of single domain antibodies onto liposomes containing the photosensitizer zinc phthalocyanine was developed and tested. Electronic supplementary information (ESI) available: Materials and methods. See DOI: 10.1039/c6nr00014b

  1. Vibrational spectroscopy of photosensitizer dyes for organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Perez Leon, C.

    2005-11-18

    Ruthenium(II) complexes containing polypyridyl ligands are intensely investigated as potential photosensitizers in organic solar cells. Of particular interest is their use in dye-sensitized solar cells based on nanocrystalline films of TiO{sub 2}. Functional groups of the dye allow for efficient anchoring on the semiconductor surface and promote the electronic communication between the donor orbital of the dye and the conduction band of the semiconductor. In the present work a new dye, [Ru(dcbpyH{sub 2}){sub 2}(bpy-TPA{sub 2})](PF6{sub )2}, and the well known (Bu{sub 4}N){sub 2}[Ru(dcbpyH){sub 2}(NCS){sub 2}] complex were spectroscopically characterized. The electronic transitions of both dyes showed solvatochromic shifts due to specific interactions of the ligands with the solvent molecules. The surface-enhanced Raman (SER) spectra of the dyes dissolved in water, ethanol, and acetonitrile were measured in silver and gold colloidal solutions. The results demonstrate that the dyes were adsorbed on the metallic nanoparticles in different ways for different solvents. It was also found that in the gold colloid, the aqueous solutions of both dyes did not produce any SERS signal, whereas in ethanolic solution the SERS effect was very weak. Deprotonation, H-bonding, and donor-acceptor interactions seem to determine these different behaviors. Our results indicate the important role of the charge transfer mechanism in SERS. The adsorption of the dye on two different TiO{sub 2} substrates, anatase paste films and anatase nanopowder, was also studied to clarify the role of the carboxylate groups in the anchoring process of the dyes on the semiconductor surface. The recorded spectra indicate a strong dependence of the anchoring configuration on the morphology of the semiconductor. (orig.)

  2. Assessing impact of manufacturing and package configurations to photosensitive compounds.

    Science.gov (United States)

    Carvalho, Thiago C; Escotet, Megerle L; Lin, Judy; Sprockel, Omar L

    2016-01-01

    Determining liability of photosensitive compounds during manufacturing, packaging, and storage remains a challenge for formulation scientists prior to the confirmatory photostability studies as per International Conference on Harmonisation (ICH) Q1B guideline. The purpose of this study was to determine the effect of light exposure to bulk process intermediates and drug product in the manufacturing environment as well as to evaluate package configurations for tablets containing Compound A. Samples were analyzed for both photodegradant levels and tablet appearance. Final blend, uncoated tablets, and coated tablets were exposed to fluorescent light relevant to the manufacturing environment. Final blend presented linear photodegradant growth from 6 to 72 h of equivalent light exposure in the manufacturing environment. Change in color of uncoated tablets occurred before quantifiable levels of photodegradant were reached. The film-coated tablets did not show photodegradation above quantifiable levels or a color shift for up to 48 h. Tablets in open conditions and packaged in HPDE bottles and PVC/Aclar (clear and opaque) were exposed to light at 1 × and 3 × the cumulative light exposure as defined in the ICH Q1B using Option 2 as the light source. The results showed that photodegradation is not a concern for all package configurations investigated and that extreme light exposure may cause a slight color shift for tablets in packages made of transparent materials. Most importantly, the study design presented herein provided a framework for an end-to-end evaluation of risks of manufacturing and packaging of tablets containing photolabile compounds prior to performing confirmatory photostability studies.

  3. Tin Tungstate Nanoparticles: A Photosensitizer for Photodynamic Tumor Therapy.

    Science.gov (United States)

    Seidl, Carmen; Ungelenk, Jan; Zittel, Eva; Bergfeldt, Thomas; Sleeman, Jonathan P; Schepers, Ute; Feldmann, Claus

    2016-03-22

    The nanoparticulate inorganic photosensitizer β-SnWO4 is suggested for photodynamic therapy (PDT) of near-surface tumors via reiterated 5 min blue-light LED illumination. β-SnWO4 nanoparticles are obtained via water-based synthesis and comprise excellent colloidal stability under physiological conditions and high biocompatibility at low material complexity. Antitumor and antimetastatic effects were investigated with a spontaneously metastasizing (4T1 cells) orthotopic breast cancer BALB/c mouse model. Besides protamine-functionalized β-SnWO4 (23 mg/kg of body weight, in PBS buffer), chemotherapeutic doxorubicin was used as positive control (2.5 mg/kg of body weight, in PBS buffer) and physiological saline (DPBS) as a negative control. After 21 days, treatment with β-SnWO4 resulted in a clearly inhibited growth of the primary tumor (all tumor volumes below 3 cm(3)) as compared to the doxorubicin and DPBS control groups (volumes up to 6 cm(3)). Histological evaluations of lymph nodes and lungs as well as the volume of ipsilateral lymph nodes show a remarkable antimetastatic effect being similar to chemotherapeutic doxorubicin but-according to blood counts-at significantly reduced side effects. On the basis of low material complexity, high cytotoxicity under blue-light LED illumination at low dark and long-term toxicity, β-SnWO4 can be an interesting addition to PDT and the treatment of near-surface tumors, including skin cancer, esophageal/gastric/colon tumors as well as certain types of breast cancer.

  4. Topical delivery of a preformed photosensitizer for photodynamic therapy of cutaneous lesions

    Science.gov (United States)

    Oleinick, Nancy L.; Kenney, Malcolm E.; Lam, Minh; McCormick, Thomas; Cooper, Kevin D.; Baron, Elma D.

    2012-02-01

    Photosensitizers for photodynamic therapy (PDT) are most commonly delivered to patients or experimental animals via intravenous injection. After initial distribution throughout the body, there can be some preferential accumulation within tumors or other abnormal tissue in comparison to the surrounding normal tissue. In contrast, the photosensitizer precursor, 5-aminolevulinic acid (ALA) or one of its esters, is routinely administered topically, and more specifically, to target skin lesions. Following metabolic conversion to protoporphyrin IX, the target area is photoilluminated, limiting peripheral damage and targeting the effective agent to the desired region. However, not all skin lesions are responsive to ALA-PDT. Topical administration of fully formed photosensitizers is less common but is receiving increased attention, and some notable advances with selected approved and experimental photosensitizers have been published. Our team has examined topical administration of the phthalocyanine photosensitizer Pc 4 to mammalian (human, mouse, pig) skin. Pc 4 in a desired formulation and concentration was applied to the skin surface at a rate of 5-10 μL/cm2 and kept under occlusion. After various times, skin biopsies were examined by confocal microscopy, and fluorescence within regions of interest was quantified. Early after application, images show the majority of the Pc 4 fluorescence within the stratum corneum and upper epidermis. As a function of time and concentration, penetration of Pc 4 across the stratum corneum and into the epidermis and dermis was observed. The data indicate that Pc 4 can be delivered to skin for photodynamic activation and treatment of skin pathologies.

  5. In Vitro Antimicrobial Photodynamic Therapy Against Trichophyton mentagrophytes Using New Methylene Blue as the Photosensitizer.

    Science.gov (United States)

    López-Chicón, P; Gulías, Ò; Nonell, S; Agut, M

    2016-11-01

    Antimicrobial photodynamic therapy combines the use of a photosensitizing drug with light and oxygen to eradicate pathogens. Trichophyton mentagrophytes is a dermatophytic fungus able to invade the skin and keratinized tissues. We have investigated the use of new methylene blue as the photosensitizing agent for antimicrobial photodynamic therapy to produce the in vitro inactivation of T mentagrophytes. A full factorial design was employed to optimize the parameters for photoinactivation of the dermatophyte. The parameters studied were new methylene blue concentration, contact time between the photosensitizing agent and the fungus prior to light treatment, and the fluence of red light (wavelength, 620-645nm) applied. The minimum concentration of new methylene blue necessary to induce the death of all T. mentagrophytes cells in the initial suspension (approximate concentration, 10(6) colony forming units per milliliter) was 50μM for a fluence of 81J/cm(2) after a contact time of 10minutes with the photosensitizing-agent. Increasing the concentration to 100μM allowed the fluence to be decreased to 9J/cm(2). Comparison of our data with other published data shows that the susceptibility of T. mentagrophytes to antimicrobial photodynamic therapy with new methylene blue is strain-dependent. New methylene blue is a photosensitizing agent that should be considered for the treatment of fungal skin infections caused by this dermatophyte. Copyright © 2016 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.

  6. Mechanism of colon cancer cell apoptosis mediated by pyropheophorbide-a methylester photosensitization.

    Science.gov (United States)

    Matroule, J Y; Carthy, C M; Granville, D J; Jolois, O; Hunt, D W; Piette, J

    2001-07-05

    Pyropheophorbide-a methylester (PPME) is a second generation of photosensitizers used in photodynamic therapy (PDT). We demonstrated that PPME photosensitization triggered apoptosis of colon cancer cells as measured by using several classical parameters such as DNA laddering, PARP cleavage, caspase activation and mitochondrial release of cytochrome c. Preincubation of cells with N-acetyl cysteine (NAC) or pyrolidine dithiocarbamate (PDTC) protected against apoptosis mediated by PPME photosensitization showing that reactive oxygen species (ROS) are involved as second messengers. On the other hand, photosensitization carried out in the presence of deuterium oxide (D2O) which enhances singlet oxygen (1O2) lifetime only increases necrosis without affecting apoptosis. Since PPME was localized in the endoplasmic reticulum (ER)/Golgi system and lysosomes, other messengers than ROS were tested such as calcium, Bid, Bap31, phosphorylated Bcl-2 and caspase-12 but none was clearly identified as being involved in triggering cytochrome c release from mitochondria. On the other hand, we demonstrated that the transduction pathways leading to NF-kappaB activation and apoptosis were clearly independent although NF-kappaB was shown to counteract apoptosis mediated by PPME photosensitization.

  7. The effect of lipid composition on the permeability of fluorescent markers from photosensitized membranes.

    Science.gov (United States)

    Ytzhak, Shany; Weitman, Hana; Ehrenberg, Benjamin

    2013-01-01

    There is evidence indicating that the cellular locus of PDT action by amphiphilic sensitizers are the cellular membranes. The photosensitization process causes oxidative damage to membrane components that can result in the cell's death. However, it was not yet established whether lipid oxidation can cause free passage of molecules through the membrane and, as a result, be the primary cause of the cell's death. In this work, we studied the effect of liposomes' lipid composition on the kinetics of the leakage of three fluorescent dyes, calcein, carboxyfluorescein and DTAF, which were trapped in the intraliposomal aqueous phase, after photosensitization with the photosensitizer deuteroporphyrin. We found that as the degree of fatty acid unsaturation increased, the photosensitized passage of these molecules through the lipid bilayer increased. We also found that the rate of leakage of these molecules was affected by their size and bulkiness as well as by their net electric charge. In liposomes that are composed of a lipid mixture similar to that of natural membranes, the observed passage of molecules through the membrane is slow. Thus, the photodynamic damage to lipids does not appear to be severe enough to be an immediate, primary cause of cell death in biological photosensitization.

  8. Photobleaching-induced changes in photosensitizing properties of dissolved organic matter

    KAUST Repository

    Niu, Xi-Zhi

    2014-12-01

    Photosensitizing properties of different dissolved organic matter (DOM) were investigated according to their performance in singlet oxygen (1O2), triplet state of DOM (3DOM*), and hydroxyl radical (·OH) productions. The photobleaching of DOM solutions after irradiation was characterized by fluorescence excitation-emission matrix and UV-Vis spectroscopy. The photosensitizing properties of pre-irradiated DOM solutions were changed in a sunlight simulator. The performance of DOMs in photosensitized degradation of several contaminants was investigated. For a 20h exposure, the observed degradation rate constant (kobs) of some contaminants decreased as a function of exposure time, and highly depended on the properties of both DOM and contaminant. Degradation of contaminants with lower kobs was more susceptible to DOM photobleaching-induced decrease in kobs. Under the current experimental conditions, the photobleaching-induced decrease of DOM photo-reactivity in contaminant degradation was mainly attributed to indirect phototransformation of DOM caused by the interactions between photo-inductive DOM moieties and photochemically-produced reactive species. Reactive contaminants can inhibit DOM indirect photobleaching by scavenging reactive species, photosensitized degradation of these contaminants exhibited a stable kobs as a result. This is the first study to report DOM photobleaching-induced changes in the simultaneous DOM photosensitized degradation of contaminants and the inhibitory effect of reactive contaminants on DOM photobleaching.

  9. Two-photon spectroscopic behaviors and photodynamic effect on the BEL-7402 cancer cells of the new chlorophyll photosensitizer

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The spectroscopic properties of a new chlorophyll derivate photosensitizer(CDP) are studied under the excitation wavelengths at 800 and 400 nm using femtosecond pulses from a Ti:sapphire laser.The damaging effect of CDP on the BEL-7402 cancer cells is also investigated upon two-photon illumination at 800 nm.The normalized fluorescence spectra of CDP in tetrahydrofuran(THF) show that two-photon and one-photon spectra have the same distributions and the same emission bands(675 nm).The life-times of two-and one-photon induced fluorescence of this molecule are of the order of 5.0 ns.By comparing the data it is shown that there is some difference between the two lifetimes,but the differ-ence is less than one nanosecond.The two-photon absorption cross section of the molecule is also measured at 800 nm and estimated as about σ′2 ≈ 31.5×10-50 cm4·s·photon-1.The results of two-photon photodynamic therapy(TPPDT) tests show that CDP can kill all of the tested cancer cells according to the usual Eosine assessment.Our results indicate that the two-photon-induced photophysical,photo-chemical and photosensitizing processes of CDP may be basically similar to those of one-photon ex-citation.These behaviors of the sample suggest that one may find other possible methods to estimate some photosensitizers’ effects in details such as their distribution in cells and the reactive targets of the sub-cellular parts of some tumor cells via two-photon excitation techniques.

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

    Directory of Open Access Journals (Sweden)

    Mikhail M Moisenovich

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

  11. An effective zinc phthalocyanine derivative for photodynamic antimicrobial chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhuo, E-mail: zchen@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry and Danish-Chinese Centre for Proteases and Cancer, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Zhou, Shanyong; Chen, Jincan [State Key Laboratory of Structural Chemistry and Danish-Chinese Centre for Proteases and Cancer, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Li, Linsen [Department of Biochemistry, Shenyang Medical College, Shenyang, Liaoning 110034 (China); Hu, Ping; Chen, Song [State Key Laboratory of Structural Chemistry and Danish-Chinese Centre for Proteases and Cancer, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Huang, Mingdong, E-mail: mhuang@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry and Danish-Chinese Centre for Proteases and Cancer, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    2014-08-01

    Bacterial infection is a common clinical problem. The emergence of antibiotic resistant bacteria posts a severe challenge to medical practice worldwide. Photodynamic antimicrobial chemotherapy (PACT) uses laser light at specific wavelength to activate oxygen molecule in the human tissue into reactive oxygen species as antimicrobial agent. This activation of oxygen by laser light is mediated through a photosensitizer. Two key properties for potent photosensitizer are its absorbance of light in the infrared region (630–700 nm), which promotes tissue penetration depth, and the selective accumulation on bacteria instead of human tissue. We herein report a zinc phthalocyanine derivative, pentalysine β-carbonylphthalocyanine zinc (ZnPc-(Lys){sub 5}) and its antimicrobial effects in vitro and in an animal infection model. This photosensitizer has strong capability to kill bacteria at 670 nm. Chemically, it is a water-soluble and cationic photosensitizer carrying positive charge under physiological pH, and can specifically target to bacteria which usually bears negative charges on its surface. Compared with anionic ZnPc counterparts, ZnPc-(Lys){sub 5} shows a higher phototoxicity toward bacteria. PACT studies of ZnPc-(Lys){sub 5} in experimental infection animal model showed a significant bacteria inhibition compared to controls, and high selectivity of ZnPc-(Lys){sub 5} toward bacteria. These findings suggest ZnPc-(Lys){sub 5} is a promising antimicrobial photosensitizer for the treatment of infectious diseases. - Highlights: • Photodynamic antimicrobial chemotherapy (PACT) with water-soluble zinc phthalocyanine derivative offers a promising measure to deal with antibiotic resistance of bacteria. • The use of portable LED light sources that are battery-powered and with low cost may make possible the deployment of systems that can be used for wound decontamination. • ZnPc-(Lys){sub 5} is a potent photosensitizer for treatment of infectious diseases.

  12. DFT-D Investigation of the Interaction Between Ir(III) Based Photosensitizers and Small Silver Clusters Ag$_n$ ($n$=2-20, 92)

    CERN Document Server

    Bokareva, Olga S

    2013-01-01

    A dispersion-corrected density functional theory study of the photosensitizer [Ir(ppy)$_2$(bpy)]$^+$ and its derivatives bound to silver clusters Ag$_n$ ($n$=2-20, 92) is performed. The goal is to provide a new system-specific set of $C_{\\rm 6}^{}$ interaction parameters for Ag and Ir atoms. To this end a QM:QM scheme is employed using the PBE functional and RPA as well as MP2 calculation as a reference. The obtained $C_{\\rm 6}^{}$ coefficients were applied to calculate dissociation curves of selected IrPS-Ag$_n$ complexes and binding energies of derivatives containing oxygen and sulphur as heteroatoms in the ligands. Comparing different $C_{\\rm 6}^{}$ parameters it is concluded that RPA-based dispersion correction produces binding energies close to standard D2 and D3 models, whereas MP2-derived parameters overestimate these energies.

  13. Detection of light images by simple tissues as visualized by photosensitized magnetic resonance imaging.

    Directory of Open Access Journals (Sweden)

    Catherine Tempel-Brami

    Full Text Available In this study, we show how light can be absorbed by the body of a living rat due to an injected pigment circulating in the blood stream. This process is then physiologically translated in the tissue into a chemical signature that can be perceived as an image by magnetic resonance imaging (MRI. We previously reported that illumination of an injected photosynthetic bacteriochlorophyll-derived pigment leads to a generation of reactive oxygen species, upon oxygen consumption in the blood stream. Consequently, paramagnetic deoxyhemoglobin accumulating in the illuminated area induces changes in image contrast, detectable by a Blood Oxygen Level Dependent (BOLD-MRI protocol, termed photosensitized (psMRI. Here, we show that laser beam pulses synchronously trigger BOLD-contrast transients in the tissue, allowing representation of the luminous spatiotemporal profile, as a contrast map, on the MR monitor. Regions with enhanced BOLD-contrast (7-61 fold were deduced as illuminated, and were found to overlap with the anatomical location of the incident light. Thus, we conclude that luminous information can be captured and translated by typical oxygen exchange processes in the blood of ordinary tissues, and made visible by psMRI (Fig. 1. This process represents a new channel for communicating environmental light into the body in certain analogy to light absorption by visual pigments in the retina where image perception takes place in the central nervous system. Potential applications of this finding may include: non-invasive intra-operative light guidance and follow-up of photodynamic interventions, determination of light diffusion in opaque tissues for optical imaging and possible assistance to the blind.

  14. DNA intercalating Ru(II) polypyridyl complexes as effective photosensitizers in photodynamic therapy.

    Science.gov (United States)

    Mari, Cristina; Pierroz, Vanessa; Rubbiani, Riccardo; Patra, Malay; Hess, Jeannine; Spingler, Bernhard; Oehninger, Luciano; Schur, Julia; Ott, Ingo; Salassa, Luca; Ferrari, Stefano; Gasser, Gilles

    2014-10-27

    Six substitutionally inert [Ru(II) (bipy)2 dppz](2+) derivatives (bipy=2,2'-bipyridine, dppz=dipyrido[3,2-a:2',3'-c]phenazine) bearing different functional groups on the dppz ligand [NH2 (1), OMe (2), OAc (3), OH (4), CH2 OH (5), CH2 Cl (6)] were synthesized and studied as potential photosensitizers (PSs) in photodynamic therapy (PDT). As also confirmed by DFT calculations, all complexes showed promising (1) O2 production quantum yields, well comparable with PSs available on the market. They can also efficiently intercalate into the DNA double helix, which is of high interest in view of DNA targeting. The cellular localization and uptake quantification of 1-6 were assessed by confocal microscopy and high-resolution continuum source atomic absorption spectrometry. Compound 1, and especially 2, showed very good uptake in cervical cancer cells (HeLa) with preferential nuclear accumulation. None of the compounds studied was found to be cytotoxic in the dark on both HeLa cells and, interestingly, on noncancerous MRC-5 cells (IC50 >100 μM). However, 1 and 2 showed very promising behavior with an increment of about 150 and 42 times, respectively, in their cytotoxicities upon light illumination at 420 nm in addition to a very good human plasma stability. As anticipated, the preferential nuclear accumulation of 1 and 2 and their very high DNA binding affinity resulted in very efficient DNA photocleavage, suggesting a DNA-based mode of phototoxic action. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Photosensitivity to Triflusal: Formation of a Photoadduct with Ubiquitin Demonstrated by Photophysical and Proteomic Techniques

    Directory of Open Access Journals (Sweden)

    E Nuin

    2016-08-01

    Full Text Available Triflusal is a platelet aggregation inhibitor chemically related to acetylsalicylic acid, which is used for the prevention and/or treatment of vascular thromboembolisms, which acts as a prodrug. Actually, after oral administration it is absorbed primarily in the small intestine, binds to plasma proteins (99% and is rapidly biotransformed in the liver into its deacetylated active metabolite 2-hydroxy-4-trifluoromethylbenzoic acid (HTB. In healthy humans, the half-life of triflusal is ca. 0.5 h, whereas for HTB it is ca. 35 h. From a pharmacological point of view, it is interesting to note that HTB is itself highly active as a platelet anti-aggregant agent. Indeed, studies on the clinical profile of both drug and metabolite have shown no significant differences between them.It has been evidenced that HTB displays ability to induce photoallergy in humans. This phenomenon involves a cell-mediated immune response, which is initiated by covalent binding of a light-activated photosensitizer (or a species derived therefrom to a protein. In this context, small proteins like ubiquitin could be appropriate models for investigating covalent binding by means of MS/MS and peptide fingerprint analysis. In previous work, it was shown that HTB forms covalent photoadducts with isolated lysine. Interestingly, ubiquitin contains seven lysine residues that could be modified by a similar reaction. With this background, the aim of the present work is to explore adduct formation between the triflusal metabolite and ubiquitin as model protein upon sunlight irradiation, combining proteomic and photophysical (fluorescence and laser flash photolysis techniques.Photophysical and proteomic analysis demonstrate monoadduct formation as the major outcome of the reaction. Interestingly, addition can take place at any of the -amino groups of the lysine residues of the protein and involves replacement of the trifluoromethyl moiety with a new amide function. This process can in

  16. Light-induced antibacterial activity of electrospun chitosan-based material containing photosensitizer.

    Science.gov (United States)

    Severyukhina, A N; Petrova, N V; Yashchenok, A M; Bratashov, D N; Smuda, K; Mamonova, I A; Yurasov, N A; Puchinyan, D M; Georgieva, R; Bäumler, H; Lapanje, A; Gorin, D A

    2017-01-01

    Increasing antimicrobial resistance requires the development of novel materials and approaches for treatment of various infections. Utilization of photodynamic therapy represents an advanced alternative to antibiotics and metal-based agents. Here, we report the fabrication of electrospun material that possesses benefits of both topical antimicrobial and photodynamic therapies. This material combines chitosan, as a biocompatible polymer, and a second generation photosensitizer. The incorporation of photosensitizer doesn't affect the material morphology and its nearly uniform distribution in fibers structure was observed by confocal Raman microscopy. Owing to photosensitizer the prepared material exhibits the light-induced and spatially limited antimicrobial activity that was demonstrated against Staphylococcus aureus, an important etiological infectious agent. Such material can be potentially used in antibacterial therapy of chronic wounds, infections of diabetic ulcers, and burns, as well as rapidly spreading and intractable soft-tissue infections caused by resistant bacteria. Copyright © 2016. Published by Elsevier B.V.

  17. Raman microspectroscopy of Hematoporphyrins. Imaging of the noncancerous and the cancerous human breast tissues with photosensitizers

    Science.gov (United States)

    Brozek-Pluska, B.; Kopec, M.

    2016-12-01

    Raman microspectroscopy combined with fluorescence were used to study the distribution of Hematoporphyrin (Hp) in noncancerous and cancerous breast tissues. The results demonstrate the ability of Raman spectroscopy to distinguish between noncancerous and cancerous human breast tissue and to identify differences in the distribution and photodegradation of Hematoporphyrin, which is a photosensitizer in photodynamic therapy (PDT), photodynamic diagnosis (PDD) and photoimmunotherapy (PIT) of cancer. Presented results show that Hematoporphyrin level in the noncancerous breast tissue is lower compared to the cancerous one. We have proved also that the Raman intensity of lipids and proteins doesn't change dramatically after laser light irradiation, which indicates that the PDT treatment destroys preferably cancer cells, in which the photosensitizer is accumulated. The specific subcellular localization of photosensitizer for breast tissues samples soaked with Hematoporphyrin was not observed.

  18. Evaluation of Different Light Conditions in the Working Environment for Handling Photosensitive and Thermolabile Compounds.

    Science.gov (United States)

    Hernandez Duran, Tania; Ravela, Neel; Sanchez Rivero, Sandra; De Jesus Castro Sandoval, Teresita; Hoogmartens, Jos; Pendela, Murali

    2015-01-01

    Lighting in the working environment plays a significant role on the degree of degradation of photosensitive, thermolabile compounds and on working efficiency. Light emitting diodes (LEDs) are semiconductor light emitting devices that are promising artificial light sources with easy modulation of light wave signals and are also known for low heat generation. Therefore, the effect of polychromatic LED light was tested in the working environment using the drug compounds montelukast, nifedipine, and clavulanic acid, which are known to be photosensitive or thermolabile. As a control, other lighting sources like a sodium lamp, a classic (incandescent, tungsten) lamp, and indirect sunlight were also used in this study. All the experiments were carried out with methanolic solutions at room temperature. An Acquity UPLC/MS/MS system was used for quantification of the main analytes and degradation products. Under the tested conditions, LED lighting proved to be more suitable for handling photosensitive and thermolabile compounds.

  19. Inhibiting the photosensitized oxidation of anthracene and tryptophan by means of natural antioxidants

    Science.gov (United States)

    Aksenova, N. A.; Vyzhlova, E. N.; Malinovskaya, V. V.; Parfenov, V. V.; Solov'eva, A. B.; Timashev, P. S.

    2013-08-01

    It is shown that model reactions of photosensitized oxidation of anthracene and tryptophan can be used for evaluation and comparison of antioxidant activity of various classes of compounds. Inhibition of the oxidation of substrates in the presence of the familiar antioxidants tocopherol (vitamin E), ascorbic acid (vitamin C), and mixtures of these vitamins with methionine, and in the presence of reputed antioxidants dihydroquercetin and taurine, are considered. It is concluded that all of the above compounds except for taurine have antioxidant properties; i.e., they reduce the rate constants of the photosensitized oxidation of anthracene and tryptophan. It is found that the inhibition of oxidation is associated with the interaction between antioxidants and singlet oxygen. Analysis of the kinetic dependences of the photosensitized oxidation of substrates in the presence of antioxidants reveals that a mixture of vitamins inhibits the process most efficiently, and inhibition occurs at the initial stages due to more active interaction between singlet oxygen and vitamin C

  20. Immediate pigment darkening: its evolutionary roles may include protection against folate photosensitization.

    Science.gov (United States)

    Moan, Johan; Nielsen, Kristian Pagh; Juzeniene, Asta

    2012-03-01

    The evolution of dark human skin colors in tropical areas is possibly related to photoprotection of folates. However, natural folates absorb mainly UVB radiation, and too little UVB can penetrate down to folates in dermal vessels to cause serious damage. However, endogenous photosensitizers, like riboflavin and uroporphyrin, absorbing UVA and visible light, can cause photosensitization of folates. Immediate pigment darkening (IPD), generated by UVA, has an absorption spectrum covering those of the endogenous photosensitizers. IPD is most prominent for darker skin types, which were typical for populations living under tropical solar fluences. We here propose that the biological role of IPD is protection of folates against photodegradation, which would be of large evolutionary importance for early hominids.

  1. Enhanced photodynamic antitumor effect on gastric cancer by a novel photosensitive stealth liposome.

    Science.gov (United States)

    Namiki, Yoshihisa; Namiki, Tamami; Date, Masataka; Yanagihara, Kazuyoshi; Yashiro, Masakazu; Takahashi, Hiroshi

    2004-07-01

    Lipophilic photosensitizers hold potential for cancer photodynamic therapy. We sought to develop a novel photosensitive stealth liposome (PSSL) which incorporating a lipophilic photosensitizer into its lipid bilayer and to examine its photoactivity. We prepared PSSL composed of lipophilic chlorin e6 (Ce6) ester, dilauroylphosphatidylcholine, dioleoylphosphatidylethanolamine and distearoyl-phosphoethanolamine-N-[poly (ethylene glycol) 2000] and evaluated its photodynamic effect against gastric cancer cell lines and tumor-bearing nude mice models. In gastric cancer cell lines, LC(80) of PSSL was a maximum of 53 times as low as that of Ce6 sodium salt (Ce6-Na). PSSL completely destroyed all tumors in animal models and tumor recurrence levels were minimal (1.5 +/- 0.9%). PSSL achieved greater photodynamic effects in gastric cancer cell lines and in murine models than Ce6-Na. PSSL holds promise for photodynamic therapy for gastric cancer.

  2. Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure, Activity and Regulation

    Directory of Open Access Journals (Sweden)

    Jane C. Quinn

    2014-01-01

    Full Text Available Photosensitivity in animals is defined as a severe dermatitis that results from a heightened reactivity of skin cells and associated dermal tissues upon their exposure to sunlight, following ingestion or contact with UV reactive secondary plant products. Photosensitivity occurs in animal cells as a reaction that is mediated by a light absorbing molecule, specifically in this case a plant-produced metabolite that is heterocyclic or polyphenolic. In sensitive animals, this reaction is most severe in non-pigmented skin which has the least protection from UV or visible light exposure. Photosensitization in a biological system such as the epidermis is an oxidative or other chemical change in a molecule in response to light-induced excitation of endogenous or exogenously-delivered molecules within the tissue. Photo-oxidation can also occur in the plant itself, resulting in the generation of reactive oxygen species, free radical damage and eventual DNA degradation. Similar cellular changes occur in affected herbivores and are associated with an accumulation of photodynamic molecules in the affected dermal tissues or circulatory system of the herbivore. Recent advances in our ability to identify and detect secondary products at trace levels in the plant and surrounding environment, or in organisms that ingest plants, have provided additional evidence for the role of secondary metabolites in photosensitization of grazing herbivores. This review outlines the role of unique secondary products produced by higher plants in the animal photosensitization process, describes their chemistry and localization in the plant as well as impacts of the environment upon their production, discusses their direct and indirect effects on associated animal systems and presents several examples of well-characterized plant photosensitization in animal systems.

  3. Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure, Activity and Regulation

    Science.gov (United States)

    Quinn, Jane C.; Kessell, Allan; Weston, Leslie A.

    2014-01-01

    Photosensitivity in animals is defined as a severe dermatitis that results from a heightened reactivity of skin cells and associated dermal tissues upon their exposure to sunlight, following ingestion or contact with UV reactive secondary plant products. Photosensitivity occurs in animal cells as a reaction that is mediated by a light absorbing molecule, specifically in this case a plant-produced metabolite that is heterocyclic or polyphenolic. In sensitive animals, this reaction is most severe in non-pigmented skin which has the least protection from UV or visible light exposure. Photosensitization in a biological system such as the epidermis is an oxidative or other chemical change in a molecule in response to light-induced excitation of endogenous or exogenously-delivered molecules within the tissue. Photo-oxidation can also occur in the plant itself, resulting in the generation of reactive oxygen species, free radical damage and eventual DNA degradation. Similar cellular changes occur in affected herbivores and are associated with an accumulation of photodynamic molecules in the affected dermal tissues or circulatory system of the herbivore. Recent advances in our ability to identify and detect secondary products at trace levels in the plant and surrounding environment, or in organisms that ingest plants, have provided additional evidence for the role of secondary metabolites in photosensitization of grazing herbivores. This review outlines the role of unique secondary products produced by higher plants in the animal photosensitization process, describes their chemistry and localization in the plant as well as impacts of the environment upon their production, discusses their direct and indirect effects on associated animal systems and presents several examples of well-characterized plant photosensitization in animal systems. PMID:24451131

  4. Case series: indoor-photosensitivity caused by fluorescent lamps in patients treated with vemurafenib for metastatic melanoma

    NARCIS (Netherlands)

    Boudewijns, S.; Gerritsen, W.R.; Koornstra, R.H.

    2014-01-01

    BACKGROUND: Vemurafenib, a selective inhibitor of genetically activated BRAF, is registered for unresectable stage III and stage IV melanomas harboring a BRAF mutation. Photosensitivity related to exposure to sunlight is a common side-effect. We here present three cases of indoor-photosensitivity

  5. Inactivation of several strains of Listeria monocytogenes attached to the surface of packaging material by Na-Chlorophyllin-based photosensitization.

    Science.gov (United States)

    Luksiene, Zivile; Buchovec, Irina; Paskeviciute, Egle

    2010-12-02

    This study was focused on the possibility to inactivate thermosensitive Listeria monocytogenes ATC(L3)C 7644 and thermoresistant 56 Ly strain by Na-Chlorophyllin (Na-Chl)-based photosensitization in vitro and on the surface of packaging. Comparative analysis of antimicrobial efficiency of photosensitization with conventional surface cleaning was performed. Data indicate that both Listeria strains, after incubation with Na-Chl and following illumination (λ=400nm, 20mWcm(-2)), were inactivated by 7 log in vitro. This treatment cleaned both Listeria strains from packaging surfaces. Comparative analysis indicates that washing with water diminishes pathogens by less than 1 log, 200ppm Na-hypochlorite by 1.7 log, Na-Chl-based photosensitization by 4.5 log. Listeria biofilms were totally removed from the surface by photosensitization at higher photosensitizer concentrations and longer incubation times. In conclusion, both strains of L. monocytogenes can be effectively inactivated by photosensitization in vitro and on the surface of packaging. Listeria biofilms are susceptible to this treatment as well. Comparison of different surface decontamination treatments reveals that photosensitization is much more effective against both Listeria strains than washing with water or 200ppm Na-hypochlorite. Our data support the idea that Na-Chl-based photosensitization is an effective antimicrobial tool which may serve in the future for the development of human and environmentally friendly surface decontamination techniques.

  6. Case series: indoor-photosensitivity caused by fluorescent lamps in patients treated with vemurafenib for metastatic melanoma

    NARCIS (Netherlands)

    Boudewijns, S.; Gerritsen, W.R.; Koornstra, R.H.

    2014-01-01

    BACKGROUND: Vemurafenib, a selective inhibitor of genetically activated BRAF, is registered for unresectable stage III and stage IV melanomas harboring a BRAF mutation. Photosensitivity related to exposure to sunlight is a common side-effect. We here present three cases of indoor-photosensitivity du

  7. Case series: indoor-photosensitivity caused by fluorescent lamps in patients treated with vemurafenib for metastatic melanoma

    NARCIS (Netherlands)

    Boudewijns, S.; Gerritsen, W.R.; Koornstra, R.H.

    2014-01-01

    BACKGROUND: Vemurafenib, a selective inhibitor of genetically activated BRAF, is registered for unresectable stage III and stage IV melanomas harboring a BRAF mutation. Photosensitivity related to exposure to sunlight is a common side-effect. We here present three cases of indoor-photosensitivity du

  8. Preparation and Photodynamic Anti-tumor Activity of Magnetic Polylactic Acid Nanoparticles Loaded with Photosensitizer

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-xia; HUANG Hui; CHEN Zhi-long; HUANG Peng; SUN Yun; ZHOU Xing-ping

    2010-01-01

    A novel magnetic nanocarrier was strategically designed and successfully prepared. Photosensitizer 2, 7,12, 18-tetramethyl-3, 8-di-(1-propoxyethyl)-13, 17-bis-( 3-hydroxypropyl ) porphyrin ( PHPP ) wasencapsulated into polylactic acid (PLA)-coated Fe3O4nanoparticles. The diameter of nanocarrier is 30-50 nm by transmission electron micrograph ( TEM ). The encapsulation efficiency of photosensitizer is 27.98% calculated from UV-vis absorption spectra. The nanocarrier shows obvious photocytotoxic activity to Hela299 tumor cells in vitro.

  9. Histology of the iris in geese and ducks photosensitized by ingestion of Ammi majus seeds.

    Science.gov (United States)

    Barishak, Y R; Beemer, A M; Egyed, M N; Shlosberg, A; Eilat, A

    1975-09-01

    Geese and ducks were photosensitized by the ingestion of Ammi majus seeds, and exposure to sunlight. Mydriasis was a characteristic clinical feature of this syndrome in both species. Histologically the iris of the affected birds showed vacuolisation and varying degrees of atrophy of the muscle of the sphincter pupillae. The effect of pilocarpine and physostigmine on the normal and mydriatic eyes was studied. The possible mode of action of photosensitization and the significance of these findings in the light of the use of psoralens in human medicine is discussed.

  10. The susceptibility of young chickens, ducks, and turkeys to the photosensitizing effect of Ammi visnaga seeds.

    Science.gov (United States)

    Egyed, M N; Shlosberg, A; Eilat, A

    1975-01-01

    Young chickens, ducks, and turkeys were exposed to sunlight and fed various amounts of Ammi visnaga seeds for 14 days in an attempt to induce photosensitization. In chickens, seeds at 1.25% in the diet had no effect whereas 3% induced mild signs of photosensitization within 6 to 8 days. No visible effects resulted in ducklings from 1.5, 3 and 6% in the diet, or in turkey poults from 3%. These differences appear to be due to differences between these avian species in the metabolism of the photodynamic agent.

  11. Photosensitivity of heterojunctions formed by deposition of gum on a layered III VI semiconductor

    Science.gov (United States)

    Drapak, S. I.; Kovalyuk, Z. D.

    2007-09-01

    The list of materials showing promise for the production of photosensitive structures is extended to include an organic material of biological origin known as gum. The current-voltage characteristics of hetero-junctions formed by a gum layer and a layered semiconductor (InSe, GaSe) are studied. An attempt is made to relate some spectral features of the relative quantum efficiency of the structures (for example, nonzero photosensitivity beyond the fundamental absorption edge of the semiconductor material) to the deformation interaction between the condensed gum layer and the layered III VI semiconductor surface.

  12. Fluorescence Characteristics and Lifetime Images of Photosensitizers of Talaporfin Sodium and Sodium Pheophorbide a in Normal and Cancer Cells

    Directory of Open Access Journals (Sweden)

    Kamlesh Awasthi

    2015-05-01

    Full Text Available Fluorescence spectra and fluorescence lifetime images of talaporfin sodium and sodium-pheophorbide a, which can be regarded as photosensitizers for photodynamic therapy, were measured in normal and cancer cells. The reduction of the fluorescence intensity by photoirradiation was observed for both photosensitizers in both cells, but the quenching rate was much faster in cancer cells than in normal cells. These results are explained in terms of the excessive generation of reactive oxygen species via photoexcitation of these photosensitizers in cancer cells. The fluorescence lifetimes of both photosensitizers in cancer cells are different from those in normal cells, which originates from the different intracellular environments around the photosensitizers between normal and cancer cells.

  13. Prostaglandin E2 is critical for the development of niacin-deficiency-induced photosensitivity via ROS production

    Science.gov (United States)

    Sugita, Kazunari; Ikenouchi-Sugita, Atsuko; Nakayama, Yasuko; Yoshioka, Haruna; Nomura, Takashi; Sakabe, Jun-Ichi; Nakahigashi, Kyoko; Kuroda, Etsushi; Uematsu, Satoshi; Nakamura, Jun; Akira, Shizuo; Nakamura, Motonobu; Narumiya, Shuh; Miyachi, Yoshiki; Tokura, Yoshiki; Kabashima, Kenji

    2013-10-01

    Pellagra is a photosensitivity syndrome characterized by three ``D's'': diarrhea, dermatitis, and dementia as a result of niacin deficiency. However, the molecular mechanisms of photosensitivity dermatitis, the hallmark abnormality of this syndrome, remain unclear. We prepared niacin deficient mice in order to develop a murine model of pellagra. Niacin deficiency induced photosensitivity and severe diarrhea with weight loss. In addition, niacin deficient mice exhibited elevated expressions of COX-2 and PGE syntheses (Ptges) mRNA. Consistently, photosensitivity was alleviated by a COX inhibitor, deficiency of Ptges, or blockade of EP4 receptor signaling. Moreover, enhanced PGE2 production in niacin deficiency was mediated via ROS production in keratinocytes. In line with the above murine findings, human skin lesions of pellagra patients confirmed the enhanced expression of Ptges. Niacin deficiency-induced photosensitivity was mediated through EP4 signaling in response to increased PGE2 production via induction of ROS formation.

  14. Application of L-cystein derivative to DNA microarray.

    Science.gov (United States)

    Nakauchi, Gen; Inaki, Yoshiaki; Kitaoka, Shiho; Yokoyama, Chieko; Tanabe, Tadashi

    2002-01-01

    S-carboxymethyl-L-cystein derivatives of nucleic acid bases were prepared as DNA chip probe. These compounds in vitro have been found to form stable complex with oligo-DNA and RNA. This paper deals with preparing new DNA chip using L-cystein derivative synthetic nucleotides as probe and immobilized it to quartz plate by photosensitive PVA. Then the chip exposed with FITC labeled target DNA was observed by confocal fluorescence microscope.

  15. Syntheses and absorption-structure relationships of some new photosensitizer cyanine dyes

    Indian Academy of Sciences (India)

    H A Shindy; A I M Koraiem

    2002-04-01

    New biheterocyclic compound was synthesized as starting material to prepare new photosensitizers mono-, tri-, substituted tri-, azadimethine and mixed cyanine dyes. Absorption-structure relationship of the synthesized cyanine dyes were determined by studying their electronic spectral behaviour in ethanol. The structure of the compounds were identified by elemental analysis, IR and 1H NMR spectral data.

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

    Science.gov (United States)

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

    2012-01-01

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

  17. Photochemical events during photosensitization of colloidal ZnO nanoparticles by riboflavin

    Indian Academy of Sciences (India)

    E Vaishnavi; R Renganathan

    2012-12-01

    The photosensitization of colloidal ZnO nanoparticles with riboflavin (RF) was investigated using absorption, fluorescence spectroscopic measurements and time resolved fluorescence measurements. Riboflavin adsorbed strongly on the surface of ZnO nanoparticles. Apparent association constant was obtained from the fluorescence quenching measurements. The free energy change, et, for electron transfer process has been calculated by applying Rehm Weller equation.

  18. Study of doping non-PMMA polymer fibre canes with UV photosensitive compounds

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Fasano, Andrea; Janting, Jakob;

    2016-01-01

    We propose a solution doping method for polycarbonate (PC) and TOPAS polymer optical fibre (POF) canes using different UV photosensitive dopants aiming to reduce the fibre Bragg grating inscription time at the typical Bragg grating inscription wavelength (325nm). Three-ring solid-core PC mPOF canes...

  19. Pigments from UV-resistant Antarctic bacteria as photosensitizers in Dye Sensitized Solar Cells.

    Science.gov (United States)

    Órdenes-Aenishanslins, N; Anziani-Ostuni, G; Vargas-Reyes, M; Alarcón, J; Tello, A; Pérez-Donoso, J M

    2016-09-01

    Here we report the use of pigments produced by UV-resistant Antarctic bacteria as photosensitizers in Dye Sensitized Solar Cells (DSSCs). Pigments were obtained from red and yellow colored psychrotolerant bacteria isolated from soils of King George Island, Antarctica. Based on metabolic characteristics and 16s DNA sequence, pigmented bacteria were identified as Hymenobacter sp. (red) and Chryseobacterium sp. (yellow). Pigments produced by these microorganisms were extracted and classified as carotenoids based on their spectroscopic and structural characteristics, determined by UV-Vis spectrophotometry and infrared spectroscopy (FTIR), respectively. With the purpose of develop green solar cells based on bacterial pigments, the photostability and capacity of these molecules as light harvesters in DSSCs were determined. Absorbance decay assays determined that bacterial carotenoids present high photostability. In addition, solar cells based on these photosensitizers exhibit an open circuit voltage (VOC) of 435.0 [mV] and a short circuit current density (ISC) of 0.2 [mA·cm(-2)] for the red pigment, and a VOC of 548.8 [mV] and a ISC of 0.13 [mA·cm(-2)] for the yellow pigment. This work constitutes the first approximation of the use of pigments produced by non-photosynthetic bacteria as photosensitizers in DSSCs. Determined photochemical characteristics of bacterial pigments, summed to their easy obtention and low costs, validates its application as photosensitizers in next-generation biological solar cells.

  20. Lupus-like histopathology in bloom syndrome: reexamining the clinical and histologic implications of photosensitivity.

    Science.gov (United States)

    McGowan, Joseph; Maize, John; Cook, Joel

    2009-12-01

    Bloom syndrome is a rare genodermatosis of autosomal recessive inheritance. Although lupus-like skin lesions characterize this disorder, mechanisms of photosensitivity are poorly understood. In this case presentation, the authors report a patient with Bloom syndrome whose lupus-like facial rash revealed striking histopathologic similarities to cutaneous lupus erythematosus.

  1. (Pheo)melanin photosensitizes UVA-induced DNA damage in cultured human melanocytes

    NARCIS (Netherlands)

    Wenczl, E.; Schans, G.P. van der; Roza, L.; Kolb, R.M.; Timmerman, A.J.; Smit, N.P.M.; Pavel, S.; Schothorst, A.A.

    1998-01-01

    The question of whether melanins are photoprotecting and/or photosensitizing in human skin cells continues to be debated. To evaluate the role of melanin upon UVA irradiation, DNA single-strand breaks (ssb) were measured in human melanocytes differing only in the amount of pigment produced by

  2. Uptake of photosensitizers by bacteria is influenced by the presence of cations

    Science.gov (United States)

    Kishen, A.; George, S.

    2007-05-01

    This investigation studies the influence of cations on photosensitizer uptake by Enterococcus faecalis (gram positive) and Actinobacillus actinomycetemcomitans (gram negative). Methods- The uptake of Methylene blue (MB) and Indocyanine Green (ICG), by bacteria were studied under the influence of divalent cations (CaCl II & MgCl II) and EDTA. Further, E. faecalis cells subjected to trypsinisation and calcium channel blocker (verapamil) were also analysed for MB and ICG uptake inorder to understand the mechanism of photosensitizer uptake. Results- Uptake of ICG was enhanced in the presence of divalent cations in E. faecalis and A. actinomycetemcomitans. Treating cells with EDTA had no significant effect on the photosensitizer uptake, although the highest concentration tested showed an enhancement of uptake. In contrast to ICG, MB showed a decreased uptake by bacterial cells on subjecting them to divalent cations and EDTA. Calcium channel blocker had no significant inhibitory effect on photosensitizers uptake. However, trypsin treatment resulted in significant reduction of ICG uptake. The result suggested that ICG uptake by bacteria is mediated through specific transporter protein while MB is associated with the outer surface structures of bacterial cells.

  3. Encapsulation of palladium porphyrin photosensitizer in layered metal oxide nanoparticles for photodynamic therapy against skin melanoma

    Science.gov (United States)

    Chen, Zih-An; Kuthati, Yaswanth; Kankala, Ranjith Kumar; Chang, Yu-Chuan; Liu, Chen-Lun; Weng, Ching-Feng; Mou, Chung-Yuan; Lee, Chia-Hung

    2015-10-01

    We designed a biodegradable nanocarrier of layered double hydroxide (LDH) for photodynamic therapy (PDT) based on the intercalation of a palladium porphyrin photosensitizer (PdTCPP) in the gallery of LDH for melanoma theragnosis. Physical and chemical characterizations have demonstrated the photosensitizer was stable in the layered structures. In addition, the synthesized nanocomposites rendered extremely efficacious therapy in the B16F10 melanoma cell line by improving the solubility of the hydrophobic PdTCPP photosensitizer. The detection of singlet oxygen generation under irradiation at the excitation wavelength of a 532 nm laser was indeed impressive. Furthermore, the in vivo results using a tumour xenograft model in mice indicated the apparent absence of body weight loss and relative organ weight variation to the liver and kidney demonstrated that the nanocomposites were biosafe with a significant reduction in tumour volume for the anti-cancer efficacy of PDT. This drug delivery system using the nanoparticle-photosensitizer hybrid has great potential in melanoma theragnosis.

  4. Highly photosensitive graphene field-effect transistor with optical memory function

    Science.gov (United States)

    Ishida, Shohei; Anno, Yuki; Takeuchi, Masato; Matsuoka, Masaya; Takei, Kuniharu; Arie, Takayuki; Akita, Seiji

    2015-10-01

    Graphene is a promising material for use in photodetectors for the ultrawide wavelength region: from ultraviolet to terahertz. Nevertheless, only the 2.3% light absorption of monolayer graphene and fast recombination time of photo-excited charge restrict its sensitivity. To enhance the photosensitivity, hybridization of photosensitive material and graphene has been widely studied, where the accumulated photo-excited charge adjacent to the graphene channel modifies the Fermi level of graphene. However, the charge accumulation process slows the response to around a few tens of seconds to minutes. In contrast, a charge accumulation at the contact would induce the efficient light-induced modification of the contact resistance, which would enhance its photosensitivity. Herein, we demonstrate a highly photosensitive graphene field-effect transistor with noise-equivalent power of ~3 × 10-15 W/Hz1/2 and with response time within milliseconds at room temperature, where the Au oxide on Au electrodes modulates the contact resistance because of the light-assisted relaxation of the trapped charge at the contact. Additionally, this light-induced relaxation imparts an optical memory function with retention time of ~5 s. These findings are expected to open avenues to realization of graphene photodetectors with high sensitivity toward single photon detection with optical memory function.

  5. (Pheo)melanin photosensitizes UVA-induced DNA damage in cultured human melanocytes

    NARCIS (Netherlands)

    Wenczl, E.; Schans, G.P. van der; Roza, L.; Kolb, R.M.; Timmerman, A.J.; Smit, N.P.M.; Pavel, S.; Schothorst, A.A.

    1998-01-01

    The question of whether melanins are photoprotecting and/or photosensitizing in human skin cells continues to be debated. To evaluate the role of melanin upon UVA irradiation, DNA single-strand breaks (ssb) were measured in human melanocytes differing only in the amount of pigment produced by cultur

  6. Atmospheric effects on the photosensitive response of poly(methylphenylsilane) thin films.

    Energy Technology Data Exchange (ETDEWEB)

    Potter, Barrett George, Jr. (University of Arizona, Tucson, AZ); Chandra, Haripin (University of Arizona, Tucson, AZ); Simmons-Potter, Kelly (University of Arizona, Tucson, AZ); Thomes, William Joseph, Jr.; Jamison, Gregory Marks

    2004-06-01

    Agile ready-when-needed patterning of refractive index structures in photosensitive materials requires an understanding of the impact of local application environment on mechanisms contributing to the desired photoinduced index change. The present work examines the impact of atmosphere on the photosensitive response of poly(methylphenylsilane) (PMPS) thin films whose high photoinduced index change under low incident optical fluence make them attractive candidates for such applications. Changes in optical absorption and refractive index are investigated after exposure to ultraviolet (UV) light resonant with the lowest energy transition exhibited by the Si-Si backbone structure in the material. A comparison between photoinduced absorption changes for thin films exposed in an air atmosphere versus those observed for samples subjected to a nitrogen environment during photoexposure is made for the first time. The study reveals that the anaerobic conditions of the nitrogen atmosphere significantly reduce the photosensitive response of the material to light. These results are discussed in terms of photooxidation processes within the polysilane structure and in the context of the need for predictable photosensitive refractive index change in varied photoimprinting environments.

  7. Time-lapse microscopy studies of bystander effects induced by photosensitization

    Science.gov (United States)

    Chen, Yin-Chu; Redmond, Robert W.

    2006-02-01

    Reactive oxygen species (ROS) are involved in the pathogenesis of many critical diseases and are also utilized as cytotoxic agents in a variety of treatments for eradication of diseased tissue, including cancer. Oxidative stress ensues when the level of ROS in a system exceeds the antioxidant capacity. Oxidative stress can have local (direct) and long-range (bystander) effects in cells and tissue and this research was carried out to determine the spatial and temporal nature of the photosensitized bystander effect using time-lapse fluorescence microscopy. By initiating photosensitization in only a portion of the microscopic imaging field it was possible to differentiate direct from bystander effects in EMT-6 murine breast cancer cells in 6-well plates. Elevated ROS levels are seen immediately following photodynamic treatment in direct cells with a delayed increase in oxidative stress observed in bystander cells. Cytotoxicity is also seen at earlier times in direct cells and occurs in bystander cells in a delayed fashion. These studies confirm the existence of a bystander effect following photosensitization and implicate mediators capable of diffusing in an intercellular manner from directly photosensitized cells to bystander cells and also implicate increased oxidative stress as a mechanistic factor in generating damage in bystander cells.

  8. New Approach to Inactivation of Harmful and Pathogenic Microorganisms by Photosensitization

    Directory of Open Access Journals (Sweden)

    Živile Lukšiene

    2005-01-01

    Full Text Available Photosensitization is a treatment involving the administration of a photoactive compound that selectively accumulates in the target cells or microorganisms and is followed by irradiation with visible light. The combination of the two absolutely nontoxic elements, drug and light, in the presence of oxygen results in the selective destruction of target microorganism. It is important to note that truly major advances have been made in photosensitized antimicrobial chemotherapy, in particular disinfection of the blood and blood products, or treating local infections. By no means, prevention of any disease by microbial control of environment, including food manufacturing, is of greatest importance. Thus, development of new antimicrobial methods is necessary. In this context, photosensitization has been shown to be really effective: different microorganisms such as drug-resistant bacteria, yeasts, viruses and parasites can be inactivated by this method. So far, a photosensitization phenomenon can open new and interesting avenues for the development of novel, effective and ecologically friendly antimicrobial treatment, which might be applied to increase food safety.

  9. Preclinical studies of vascular acting photosensitizer bacteriopheophorbide for the treatment of prostate cancer

    Science.gov (United States)

    Hetzel, Fred W.; Chen, Qun; Luck, David; Beckers, Jill; Huang, Zheng

    2004-06-01

    Photodynamic therapy (PDT) mediated with vascular acting photosensitizer pd-bacteriopheophorbide (Tookad), is investigated as an alternative modality for the total ablation of prostate cancer. In vivo normal canine prostate is used as the animal model. Interstitial PDT was performed by irradiating the surgically exposed prostates with a diode laser (763 nm, 150 mW/cm) to activate the IV infused photosensitizer drug. The prostate and its adjacent tissues were harvested and subjected to histopathological examination. At one-week post PDT, the animals recovered well with little or no urethral complications. Prostatic urethra and prostate adjacent tissues (bladder and underlying colon) were well preserved. PDT induced prostate lesions were characterized by marked hemorrhagic necrosis. Prostate lesions could be detected by MRI scan as early as 48 h post PDT. Maximum lesion size of 1.5 cm3 and 2.9 cm3 could be achieved at 50 J/cm and 100 J/cm, respectively, with interstitial treatment using a single 1-cm diffuser fiber, suggesting the Tookad-PDT is very effective in ablating prostatic tissue. Pharmacokinetic studies show that the photosensitizer is cleared rapidly from the circulation. In conclusion, the novel photosensitizer Tookad mediated PDT may provide an effective alternative to treat localized prostate cancer.

  10. Studies of vascular acting photosensitizer Tookad for the photodynamic therapy of prostate cancer

    Science.gov (United States)

    Huang, Zheng; Chen, Qun; Blanc, Dominique; Hetzel, Fred W.

    2005-01-01

    In this pre-clinical study, photodynamic therapy (PDT) mediated with a vascular acting photosensitizer Tookad (palladium-bacteriopheophorbide) is investigated as an alternative treatment modality for the ablation of prostate cancer. Canine prostate was used as the animal model. PDT was performed by interstitially irradiating the surgically exposed prostates with a diode laser (763 nm) to activate the IV infused photosensitizer. The effects of drug dose, drug-light interval, and light fluence rate on PDT efficacy were evaluated. The prostates and adjacent tissues were harvested at one-week post PDT and subjected to histopathological examination. The dogs recovered well with little or no urethral complications. Urinalysis showed trace blood. Histological examination showed minimal damage to the prostatic urethra. These indicated that the urethra was well preserved. PDT induced prostate lesions were characterized by marked hemorrhagic necrosis with a clear demarcation. Maximum lesion volume of ~3 cm3 could be achieved with a single 1-cm diffuser fiber at a dose level of 1 mg/kg and 200 J/cm, suggesting the therapy is very effective in ablating prostatic tissue. PDT induced lesion could reach the capsule layers but adjacent tissues were well preserved. The novel photosensitizer is a vascular drug and cleared rapidly from the circulation. Light irradiation can be performed during drug infusion thereby eliminating waiting time. The novel vascular acting photosensitizer Tookad-mediated PDT could provide an effective alternative to treat prostate cancer.

  11. Photosensitized enzyme deactivation and protein oxidation by axial-substituted phosphorus(V) tetraphenylporphyrins.

    Science.gov (United States)

    Ouyang, Dongyan; Hirakawa, Kazutaka

    2017-08-26

    The activity for photodynamic therapy of water-soluble cationic porphyrins, tetraphenylporphyrin P(V) complexes, was investigated. Bis(cyclohexylmethoxy)P(V)tetraphenylporphyrin (DCHMP(V)TPP), dichloroP(V)tetraphenylporphyrin (Cl2P(V)TPP), and dimethoxyP(V)tetraphenylporphyrin (DMP(V)TPP) could cause the photosensitized deactivation of tyrosinase. The tryptophan residue of human serum albumin (HSA) and several kinds of amino acids could be damaged by these P(V)porphyrins under visible light irradiation. The photosensitized damage of these biomolecules was inhibited by sodium azide, a singlet oxygen ((1)O2) quencher, and enhanced in deuterium oxide, suggesting the contribution of (1)O2. However, an excess amount of sodium azide did not completely inhibit the photosensitized damage. In addition, the redox potential measurements demonstrated the possibility of electron transfer from tryptophan and tyrosine to photoexcited P(V)porphyrins. These results suggest that electron transfer-mediated oxidation of amino acids contributes to the photosensitized protein and amino acid damage by these P(V)porphyrins. Specifically, Cl2P(V)TPP showed the highest photodamaging activity in the P(V)porphyrins used in this study. Oxidized products of amino acids by photoexcited P(V)porphyrins were analyzed with a liquid chromatography-mass spectrometer. Because of the hypoxic condition of a tumor, photodynamic therapy through a (1)O2-mediated mechanism should be restricted, and the electron transfer-mediated mechanism may improve the photodynamic effect. In the cases of these P(V)porphyrins, redox potential is the most important factor for photosensitized protein and amino acid oxidation through photoinduced electron transfer. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Epileptic spasms and early-onset photosensitive epilepsy in Patau syndrome: An EEG study.

    Science.gov (United States)

    Spagnoli, Carlotta; Kugathasan, Umaiyal; Brittain, Helen; Boyd, Stewart G

    2015-08-01

    Patau syndrome, trisomy 13, is the third commonest autosomal trisomy. It is associated with a 25-50% prevalence of epilepsy, but detailed electroclinical descriptions are rare. The occurrence of early-onset photosensitivity has recently been reported in single patients. We collected electroclinical data on 8 infants (age range from 2 months to 3 years and 9 months, median: 17 months) with Patau syndrome referred for an EEG in our Clinical Neurophysiology Department between 1991 and 2011. All EEGs, case-notes, cytogenetic diagnosis and neuroimaging when available were reviewed; data on the occurrence of seizures, epileptiform discharges, photoparoxysmal response and their characteristics in terms of positive frequencies, latencies, grade and duration were noted and analysed. Two patients had been previously diagnosed with epilepsy (one with tonic spasms and one with multiple seizure types). We found 3 patients with photosensitive myoclonic epilepsy (37.5%), and one with non-photosensitive myoclonic epilepsy. We also recorded non-epileptic myoclonic jerks in one patient known to suffer from epileptic spasms. Among photosensitive patients we found self-limited, Waltz's grade 2-4, spike-wave/polyspike-wave discharges in low, medium and high frequency ranges in two patients and in the high frequency range in the third patient, with latencies and duration from less than 1s to a maximum of 9s. In our cohort of Patau syndrome patients, we found a high prevalence of spasms and photic-induced myoclonic jerks. Photosensitivity shows an unusual early age of onset. Copyright © 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  13. Photosensitization and the photocurrent switching effect in nanocrystalline titanium dioxide functionalized with iron(II) complexes: a comparative study.

    Science.gov (United States)

    Macyk, Wojciech; Stochel, Grazyna; Szaciłowski, Konrad

    2007-01-01

    Selected iron(II) complexes (ferrocene, ferrocenylboronic acid, hexacyanoferrate(II)) have been used as photosensitizers of titanium dioxide. Various types of electronic interactions between the surface complex and the semiconducting support are reflected in different yields of photocurrent generated upon visible-light irradiation and different efficiencies of the photosensitization effect. The studied systems, showing the photocurrent switching upon changes of electrode potential and energy of photons (the PEPS effect), are good models of simple photoelectrochemical logic devices. The mechanism of photosensitization and photocurrent switching is discussed with respect to the type of surface-complex-support interaction. Quantum-mechanical calculations support the proposed mechanisms.

  14. Newly Synthesized Water Soluble Cholinium-Purpurin Photosensitizers and Their Stabilized Gold Nanoparticles as Promising Anticancer Agents

    Directory of Open Access Journals (Sweden)

    Young Key Shim

    2008-05-01

    Full Text Available For possible future use in Photodynamic Therapy (PDT and/or Photothermal Therapy (PTT of cancer and screening of cancer cells a new type of ionic liquid photosensitizer –Cholinium-Purpurin-18 (Chol-Pu-18 – was synthesized and small gold (Au nanoparticles, stabilized by this photosensitizer were prepared without adding any particular reducing agents and CTAB. UV-Vis spectroscopy and Transmission Electron Microscopy (TEM were used for characterization of the nanoparticles and FAB-MS and NMR of the ionic liquid choline hydroxide, purpurin carboxylate and their ionic liquid type of photosensitizer were obtained.

  15. Use of chloro-aluminum sulfonated phthalocyanine as a photosensitizer in the treatment of malignant tumors in dogs and cats

    Science.gov (United States)

    Peavy, George M.; Klein, Mary K.; Newman, H. C.; Roberts, Walter G.; Berns, Michael W.

    1991-05-01

    Chloro-aluminum sulfonated phthalocyanine (CASPc) has been proposed as a photosensitizing agent for photodynamic therapy (PDT) of neoplasia. This paper reviews the results of PDT treatment using CASPc as a photosensitizing agent in the treatment of 15 cats representing 23 sites of facial, solar induced squamous cell carcinoma, 4 dogs with hemangiopericytomas, 3 dogs with fibrosarcomas, and 1 dog with multiple cutaneous mast cell tumors. The results of this study to date suggest that CASPc is a good photosensitizing agent for the treatment of some forms of spontaneously occurring malignant neoplasia and should be more thoroughly evaluated for this purpose.

  16. The clinically used photosensitizer Verteporfin (VP) inhibits YAP-TEAD and human retinoblastoma cell growth in vitro without light activation

    Science.gov (United States)

    Brodowska, Katarzyna; Moujahed, Ahmad; Marmalidou, Anna; zu Horste, Melissa Meyer; Cichy, Joanna; Miller, Joan W.; Gragoudas, Evangelos; Vavvas, Demetrios G.

    2014-01-01

    Verteporfin (VP), a benzoporphyrin derivative, is clinically used in photodynamic therapy for neovascular macular degeneration. Recent studies indicate that VP may inhibit growth of hepatoma cells without photoactivation hrough inhibition of YAP-TEAD complex. In this study, we examined the effects of VP without light activation on human retinoblastoma cell lines. Verteporfin but not vehicle control inhibited the growth, proliferation and viability of human retinoblastoma cell lines (Y79 and WERI) in a dose-dependent manner and was associated with downregulation of YAP-TEAD associated downstream proto-oncogenes such as c-myc, axl, and surviving. In addition VP affected signals involved in cell migration and angiogenesis such as CTGF, cyr61, and VEGF-A but was not associated with significant effect on the mTOR/autophagy pathway. Of interest the pluripotency marker Oct4 were downregulated by Verteporfin treatment. Our results indicate that the clinically used photosensitizer VP is a potent inhibitor of cell growth in retinoblastoma cells, disrupting YAPTEAD signaling and pluripotential marker OCT4. This study highlights for the first time the role of the YAP-TEAD pathway in Retinoblastoma and suggests that VP may be a useful adjuvant therapeutic tool in treating Rb patients. PMID:24837142

  17. Comparison of photosensitivity in germanium doped silica fibers using 244 nm and 266 nm continuous wave lasers

    DEFF Research Database (Denmark)

    Jensen, Jesper Bo; Varming, Poul; Liu, B.;

    2001-01-01

    Diode pumped continuous-wave UV lasers offer an interesting alternative to frequency doubled argon-ion lasers. We report the first photosensitivity comparison using these lasers on deuterium loaded standard telecommunication fibers and unloaded experimental fibers....

  18. Detection of Hydrogen Peroxide Photogenerating from a Hypocrellin B Derivative

    Institute of Scientific and Technical Information of China (English)

    刘光艳; 马江华

    2003-01-01

    In order to further improve the photosensitizing activity of hypocrellin B (HB), the complex of 5,8-diBr-HB with Al3 + was designed and synthesized in high yield. The complex of aluminium ion with 5,8-di-Br-HB is a new water-soluble perylenequinonoid derivative with enhanced absorption over HB in the phototherapeutic window (600-900 nm). Electron paramagnetic resonance (EPR) measurement and 9,10-diphenyl-anthracene bleaching methods were used to investigate the photosensitizing activity of [ Al2 ( 5,8-di-Br-HB ) Cl4 ]n in the presence of oxygen. Singlet oxygen, superoxide anion radical, hydroxyl radical can be generated by [ Al2 (5,8-di-Br-HB) Cl4 ]n photosensitization. The results showed that the production of hydroxyl radical (*OH) by [ Al2 (5,8-di-Br-HB) Cl4 ] n photosensitization comes from the Fenton Haber-Weiss reaction and the decomposition of DMPO-1O2 adduct. Formation of H2 O2 as one of main intermediates in the photogeneration of hydroxyl radical was detected by using the catalyzed oxidation of the DPD reagent by the POD enzyme method. Moreover, the experiments of EPR spin trap and catalase enzyme excluded the effect of organoperoxide on DPD oxidization. These results further support the proposed mechanism of *OH formation.

  19. Selective Patterning of Organic Light-Emitting Diodes by Physical Vapor Deposition of Photosensitive Materials

    Science.gov (United States)

    Muroyama, Masakazu; Saito, Ichiro; Yokokura, Seiji; Tanaka, Kuniaki; Usui, Hiroaki

    2009-04-01

    A novel method of patterning polymeric thin films by the vapor deposition of a photosensitive layer followed by photopolymerization and development was proposed. This method was applied to the patterning of the emissive layer (EML) of an organic light-emitting diode (OLED). For the hole transport layer (HTL), N,N,N'-triphenyl-N'-(4-vinylphenyl)-biphenyl-4,4'-diamine (vTPD) and a zinc acrylate (ZnAc) crosslinker were coevaporated. The film was polymerized by postdeposition annealing to yield a polymeric HTL with a high resistance to organic solvents. On this HTL, the photosensitive EML was prepared by coevaporating a 9H-carbazole-9-ethylmethacrylate (CEMA) host material and 4-(dimethylamino)benzophenone (DABP) photoinitiator. UV irradiation on the EML through a photomask initiated radical polymerization, leaving a negative pattern of the irradiated region after immersion in tetrahydrofuran (THF). The photopatterning process was found to cause no damage to the film morphology or the device characteristics.

  20. PREPARATION AND PHOTOSENSITIVITY OF WATER SOLUBLE PHENOLIC RESINS CONTAINING ACRYLOYL AND QUATERNARY AMMONIUM CHLORIDE GROUPS

    Institute of Scientific and Technical Information of China (English)

    Xiao-ming Tan; Hong-quan Xie; Nai-yu Huang

    2002-01-01

    New water soluble and photocrosslinkable prepolymers containing acrylate and quaternary ammonium salt groups were synthesized from epoxy phenolic resin via ring-opening reaction with acrylic acid and with aqueous solution of triethylamine hydrochloride successively. The second reaction needs no phase transfer catalyst to accelerate, since the product formed can act as a phase transfer catalyst. The prepolymer obtained contains both photocrosslinkable acrylate groups and hydrophilic quaternary ammonium salt groups. Optimum conditions for these reactions were studied. The photosensitivity of the prepolymer was also investigated. The effects of different photoinitiators, different crosslinkable diluent monomers and amine accelerator on the photosensitivity of the prepolymer were compared. The photoinitiator of hydrogen abstraction type is still effective without using amine or alcohol as accelerator, because the prepolymer contains α H beside the OH groups formed in the ring-opening reactions.

  1. Photosensitivity of ion-exchanged Er-doped phosphate glass using 248nm excimer laser radiation.

    Science.gov (United States)

    Pissadakis, Stavros; Ikiades, Aris; Hua, Ping; Sheridan, Anna; Wilkinson, James

    2004-07-12

    The photosensitivity to 248nm excimer laser radiation of Er-doped Schott IOG-1 phosphate glass is presented. The photosensitive mechanism is investigated by employing a grating recording process. Index changes of up to ~2.0x10(-3) were measured in silver ion-exchanged samples using diffraction efficiency measurements; whereas changes of only ~10(-5) were measured for non-ion-exchanged samples. Absorption measurements allowed the identification of specific color center bands, which were attributed to the glass matrix and to the silver ions. Investigation of the exposed ion-exchanged glass using scanning electron microscopy and energy dispersive x-ray microanalysis revealed that in addition to the color centers formed, silver ion migration and ionization contribute significantly to the UV-induced index changes.

  2. In vivo studies of nanostructure-based photosensitizers for photodynamic cancer therapy.

    Science.gov (United States)

    Voon, Siew Hui; Kiew, Lik Voon; Lee, Hong Boon; Lim, Siang Hui; Noordin, Mohamed Ibrahim; Kamkaew, Anyanee; Burgess, Kevin; Chung, Lip Yong

    2014-12-29

    Animal models, particularly rodents, are major translational models for evaluating novel anticancer therapeutics. In this review, different types of nanostructure-based photosensitizers that have advanced into the in vivo evaluation stage for the photodynamic therapy (PDT) of cancer are described. This article focuses on the in vivo efficacies of the nanostructures as delivery agents and as energy transducers for photosensitizers in animal models. These materials are useful in overcoming solubility issues, lack of tumor specificity, and access to tumors deep in healthy tissue. At the end of this article, the opportunities made possible by these multiplexed nanostructure-based systems are summarized, as well as the considerable challenges associated with obtaining regulatory approval for such materials. The following questions are also addressed: (1) Is there a pressing demand for more nanoparticle materials? (2) What is the prognosis for regulatory approval of nanoparticles to be used in the clinic?

  3. Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Guo Yanyan; Zhang Peng [Department of Chemistry, New Mexico Tech, Socorro, NM 87801 (United States); Rogelj, Snezna, E-mail: pzhang@nmt.edu [Department of Biology, New Mexico Tech, Socorro, NM 87801 (United States)

    2010-02-10

    A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO{sub 2}-NH{sub 2}-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in the presence of anthracene-9,10-dipropionic acid. The capability of SiO{sub 2}-NH{sub 2}-RB nanoparticles to inactivate bacteria was tested in vitro on both gram-positive and gram-negative bacteria. The results showed that RB-decorated silica nanoparticles can inactivate MRSA and Staphylococcus epidermidis (both gram-positive) very effectively (up to eight-orders-of-magnitude reduction). Photosensitizers of such design should have good potential as antibacterial agents through a photodynamic mechanism.

  4. New 1,3,4-Oxadiazole Based Photosensitizers for Dye Sensitized Solar Cells (DSSCs

    Directory of Open Access Journals (Sweden)

    Umer Mehmood

    2015-01-01

    Full Text Available 1,3,4-Oxadiazole based photosensitizers with biphenyl, naphthalene, anthracene, and triphenylamine as the electron-donating moiety were synthesized for solar cell applications. In these photosensitizers, cyano groups were introduced as the electron acceptor and the anchor group because of their high electron-withdrawing ability and strong bonding to the semiconductor. Oxadiazole isomers were used as the π-conjugation system, which bridges the donor-acceptor systems. The electrochemical and optical properties of the sensitizers were investigated both in their native form and upon incorporation into dye sensitized solar cells. The results of UV-visible absorption spectroscopy, electrochemical impedance spectroscopic measurements, and photocurrent voltage characteristics indicate that 1,3,4-oxadiazole pi-spacer with the anthracene moiety has the highest efficiency of 2.58%. Density functional theory was employed to optimize the structures of the sensitizers and the TiO2 cluster.

  5. Transient Worsening of Photosensitivity due to Cholelithiasis in a Variegate Porphyria Patient.

    Science.gov (United States)

    Susa, Shinji; Sato-Monma, Fumiko; Ishii, Kouta; Hada, Yurika; Takase, Kaoru; Tada, Kyoko; Wada, Kiriko; Kameda, Wataru; Watanabe, Kentaro; Oizumi, Toshihide; Suzuki, Tamio; Daimon, Makoto; Kato, Takeo

    Variegate porphyria (VP) is an autosomal dominant disease caused by mutations of the protoporphyrinogen oxidase (PPOX) gene. This porphyria has unique characteristics which can induce acute neurovisceral attacks and cutaneous lesions that may occur separately or together. We herin report a 58-years-old VP patient complicated with cholelithiasis. A sequencing analysis indicated a novel c.40G>C mutation (p.G14R) in the PPOX gene. His cutaneous photosensitivity had been worsening for 3 years before the emergence of cholecystitis and it then gradually improved after cholecystectomy and ursodeoxycholic acid treatment with a slight decline in the porphyrin levels in his blood, urine and stool. In VP patients, a worsening of photosensitivity can thus be induced due to complications associated with some other disease, thereby affecting their porphyrin-heme biosynthesis.

  6. Predictive model for photodynamic therapy with gold nanoparticles as vehicle for the photosensitizer delivery

    Science.gov (United States)

    Salas-García, I.; Fanjul-Vélez, F.; Ortega-Quijano, N.; Arce-Diego, J. L.

    2013-06-01

    Photodynamic Therapy offers multiple advantages to treat nonmelanoma skin cancer compared to conventional treatment techniques such as surgery, radiotherapy or chemotherapy. Among these advantages are particularly relevant its noninvasive nature, the use of non ionizing radiation and its high selectivity. However the therapeutic efficiency of the current clinical protocol is not complete in all the patients and depends on the type of pathology. Emerging strategies to overcome its current shortcomings include the use of nanostructures that can act as carriers for conventional photosensitizers and improve the treatment selectivity and provide a controlled release of the photoactive agent. In this work, a model for photodynamic therapy combined with gold nanocarriers for a photosensitizer commonly used in dermatology is presented and applied to a basal cell carcinoma in order to predict the cytotoxic agent spatial and temporal evolution.

  7. EPR study on the photosensitized generation of reactive oxygen species by actinomycin D

    Institute of Scientific and Technical Information of China (English)

    PAN; Jingxi; (潘景喜); ZHANG; Suping; (张素萍); TU; Tiecheng; (屠铁成); HAN; Zhenhui; (韩镇辉); CAI; Xichen; (蔡喜臣); YAO; Side; (姚思德); LIN; Nianyun; (林念芸)

    2002-01-01

    Actinomycin D (AMD) is an Received anticancer antibiotic that can bind selectively to both double-stranded and single-stranded DNA, and this binding greatly enhances DNA photosensitization. Using electron paramagnetic resonance (EPR) in combination with spin trapping techniques, a systematic study was carried out on the reactive oxygen species generated in the photosensitization process of AMD. It was found that 1O2 and are important reactive intermediates either in solution or in DNA complexes, and the generation of these species is in competition. This finding suggests that the photodynamic action of AMD proceeds via two pathways: energy transfer (type I mechanism) and electron transfer (type II mechanism). 1O2 is the main product formed via energy transfer reaction in solution while electron transfer between the excited states of AMD and DNA becomes the predominant pathway in DNA complexes.

  8. Photosensitization of nanoporous TiO{sub 2} films with natural dye

    Energy Technology Data Exchange (ETDEWEB)

    Jin, En Mei; Park, Kyung-Hee; Gu, Hal-Bon [Department of Electrical Engineering, Chonnam National University, 300 Yongbon-dong, Buk-gu, Gwangju 500-757 (Korea, Republic of); Jin, Bo [Key Laboratory of Automobile Materials, Ministry of Education and School of Materials Science and Engineering, Jilin University, Changchun 130025 (China); Yun, Je-Jung, E-mail: hbgu@chonnam.ac.k [Jeonnam Nano Bio Center, 1063-50 Yeongcheon-ri, Jangseong-gun, Jeollanam-do 515-806 (Korea, Republic of)

    2010-05-01

    Dye-sensitized solar cells were assembled by using natural dyes extracted from wormwood, bamboo leaves and red maple leaves as photosensitizers. The V{sub oc} values of natural dyes from wormwood, bamboo leaves and maple leaves were 0.67, 0.66 and 0.59, respectively. The I{sub SC} values were varied from 2.56 to 5.95 mA cm{sup -2} and the fill factors from 56 to 66%. Based on investigations into the structure and properties of dye molecules, wormwood revealed the best photosensitized effects among several kinds of natural dyes, which is due to the interaction between the carbonyl and hydroxyl groups of anthocyanin and the surface of TiO{sub 2}; these wormwood extracts act as efficient sensitizers.

  9. Optical Properties of BDK-Doped Highly Photosensitive Sol-Gel Hybrid Film

    Institute of Scientific and Technical Information of China (English)

    XU Ming; SHEN Wei-Dong; ZHANG Yue-Guang; ZHEN Hong-Yu; LIU Xu

    2011-01-01

    @@ A new organic-inorganic by brid material doped with BDK that exhibits a large photo-induced change in optical properties is prepared by the sol-gel method.The photosensitivity of the film under ultraviolet irradiation is investigated with various exposure times.An increase in refractive index from 1.558 to 1.592 at A=550nm is observed together with a 57.3% expansion in physical thickness.The film's optical thickness exhibits an exponential change with the irradiation time.The photo-decomposition of BDK organic groups confirmed by the infrared absorption spectrum contributes to the photosensitive mechanism.A first example of photo-patterning is finally presented by direct light writing.

  10. Mapping a plasmonic hologram with photosensitive polymer films: standing versus propagating waves.

    Science.gov (United States)

    Papke, Thomas; Yadavalli, Nataraja Sekhar; Henkel, Carsten; Santer, Svetlana

    2014-08-27

    We use a photosensitive layer containing azobenzene moieties to map near-field intensity patterns in the vicinity of nanogrids fabricated within a thin silver layer. It is known that azobenzene containing films deform permanently during irradiation, following the pattern of the field intensity. The photosensitive material reacts only to stationary waves whose intensity patterns do not change in time. In this study, we have found a periodic deformation above the silver film outside the nanostructure, even if the latter consists of just one groove. This is in contradiction to the widely accepted viewpoint that propagating surface plasmon modes dominate outside nanogrids. We explain our observation based on an electromagnetic hologram formed by the constructive interference between a propagating surface plasmon wave and the incident light. This hologram contains a stationary intensity and polarization grating that even appears in the absence of the polymer layer.

  11. Dopamine-quantum dot conjugate: a new kind of photosensitizers for photodynamic therapy of cancers

    Energy Technology Data Exchange (ETDEWEB)

    Chou Kailiang; Meng He; Cen Yan; Li Lei; Chen Jiyao, E-mail: jychen@fudan.edu.cn [Fudan University, State Key Laboratory of Surface Physics and Department of Physics, and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) (China)

    2013-01-15

    The thiol-capped CdTe quantum dots (QDs) with the average size of 3.5 nm were linked to dopamines (DAs) forming DA-QD conjugates, with the characteristics of red-shifted photoluminescence (PL) peak and remarkably reduced PL lifetime. The QDs in the conjugates readily accept the electron from DAs when excited by the visible light, resulting in the oxidation of DAs and the production of singlet oxygen ({sup 1}O{sub 2}) with the yield comparable to that of sulfonated aluminum phthalocyanine (AlPcS), a popularly used photosensitizer. The DA-QD conjugate can quickly penetrate into human nasopharyngeal carcinoma (KB) cells and seriously destroy cells under the irradiation of visible lights, showing the potential to become a new kind of photosensitizers.

  12. Identification of singlet oxygen photosensitizes in lambs drinking water in an alveld risk area in West Norway.

    Science.gov (United States)

    Tønnesen, Hanne Hjorth; Mysterud, Ivar; Karlsen, Jan; Skulberg, Olav M; Laane, Carl M M; Schumacher, Trond

    2013-02-05

    Alveld is a hepatogenous photosensitivity disorder in lambs. Although alveld has been known in Norway for more than 100years, there are still questions related to the cause of the disease. Phytoporphyrin has long been incriminated as the photosensitizer in hepatogenous photosensitivity diseases but previous findings suggest that the photosensitizing mechanism in alveld is more complex, possibly involving other co-factors. The current work investigates the presence of non-hepatogenous photosensitizers originating in lamb's drinking water from various sources. In addition samples of two of the predominent cyanobacteria found in a representative biofilm (i.e. aggregates of microbes) were identified and isolated in axenic (i.e. pure) cultures. Information from the absorption-, fluorescence emission-, and -excitation spectra and the action spectrum for the formation of singlet oxygen was combined in order to identify the chromophores responsible for the formation of singlet oxygen, e.g. phycocyanins from the cyanobacteria. The highest level of singlet oxygen formation was detected in lotic (i.e. flowing) water in the period consistent with the outbreak of the alveld disease in the area. Meteorological data indicate a warm and wet May with a high radiation exposure leading up to a colder and wet June with an even higher solar irradiance. The seasonal variation in the amount of photosensitizers in lamb's drinking water combined meteorological data can be important to predict the outbreak of alveld. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Effective Single Photodynamic Treatment of ex Vivo Onychomycosis Using a Multifunctional Porphyrin Photosensitizer and Green Light

    OpenAIRE

    Hollander, Chelsea; Visser, Jasper; Haas, Ellen; Incrocci, Luca; Smijs, Threes

    2015-01-01

    Onychomycosis is predominantly caused by the dermatophytes Trichophyton rubrum, Trichophyton mentagrophytes and Trichophyton tonsurans. The main treatment obstacle concerns low nail-plate drug permeability. In vitro antifungal photodynamic treatment (PDT) and nail penetration enhancing effectiveness have been proven for multifunctional photosensitizer 5,10,15-tris(4-N-methylpyridinium)-20-(4-(butyramido-methylcysteinyl)-hydroxyphenyl)-[21H,23H]-porphine trichloride (PORTHE). This study invest...

  14. Production of reactive oxygen species from photosensitizers activated with visible light sources available in dental offices.

    Science.gov (United States)

    Bouillaguet, Serge; Wataha, John C; Zapata, Oscar; Campo, Marino; Lange, Norbert; Schrenzel, Jacques

    2010-08-01

    The aim of this study was to assess the ability of commonly available red- or blue-light dental sources to generate reactive oxygen species (ROS) from photosensitive chemicals that might be useful for photodynamic antimicrobial chemotherapy (PACT). Although the use of red diode lasers is well documented, there is limited information on how useful blue-light sources might be for PACT in dental contexts. A diode laser (Periowave; see Table 1 for material and equipment sources) emitting red light (660-675 nm) was used to activate toluidine blue; riboflavin and pheophorbide-a polylysine (pheophorbide-a-PLL) were photoactivated using an Optilux 501 curing unit emitting blue light (380-500 nm). Ozone gas (generated by OzoTop, Tip Top Tips, Rolle, Switzerland), sodium hypochlorite, and hydrogen peroxide were used for comparison. ROS production was estimated using an iodine-triiodide colorimetric assay, and ROS levels were plotted versus concentration of chemicals to determine each chemical's efficiency in ROS production. One-way ANOVA with Tukey post hoc analysis (alpha = 0.05) was used to compare the efficiencies of ROS production for the various chemicals. Sodium hypochlorite, hydrogen peroxide, and ozone gas produced ROS spontaneously, whereas pheophorbide-a-PLL, riboflavin, and toluidine blue required light exposure. The efficiency of ROS production was higher for pheophorbide-a-PLL and toluidine blue than for ozone gas or riboflavin (p < 0.05). Hydrogen peroxide was the least efficient ROS producer. The results of the current study support the use of blue- or red-light-absorbing photosensitizers as candidates to produce ROS for clinical applications. Blue-light photosensitizers were as efficient as red-light photosensitizers in producing ROS and more efficient than the oxidant chemicals currently used for dental disinfection.

  15. Improved stability of hydrogenated amorphous-silicon photosensitivity by ultraviolet illumination

    Science.gov (United States)

    Branz, Howard M.; Xu, Yueqin; Heck, Stephan; Gao, Wei

    2002-10-01

    Postdeposition ultraviolet (UV) illumination, followed by etching, improves the stability of hydrogenated amorphous-silicon thin films against subsequent light-induced degradation of photosensitivity. The etch removes a heavily damaged layer extending about 100 nm below the surface, but beneath the damage, the UV has improved the stability of 200 to 300 nm of bulk film. The open-circuit voltage of Schottky solar cells is also stabilized by UV-etch treatment. Possible mechanisms are discussed.

  16. Invention of a novel photodynamic therapy for tumors using a photosensitizing PI3K inhibitor.

    Science.gov (United States)

    Hayashida, Yushi; Ikeda, Yuka; Sawada, Koichi; Kawai, Katsuhisa; Kato, Takuma; Kakehi, Yoshiyuki; Araki, Nobukazu

    2016-08-01

    XL147 (SAR245408, pilaralisib), an ATP-competitive pan-class I phosphoinositide 3-kinase (PI3K) inhibitor, is a promising new anticancer drug. We examined the effect of the PI3K inhibitor on PC3 prostate cancer cells under a fluorescence microscope and found that XL147-treated cancer cells are rapidly injured by blue wavelength (430 nm) light irradiation. During the irradiation, the cancer cells treated with 0.2-2 μM XL147 showed cell surface blebbing and cytoplasmic vacuolation and died within 15 min. The extent of cell injury/death was dependent on the dose of XL147 and the light power of the irradiation. These findings suggest that XL147 might act as a photosensitizing reagent in photodynamic therapy (PDT) for cancer. Moreover, the cytotoxic effect of photosensitized XL147 was reduced by pretreatment with other ATP-competitive PI3K inhibitors such as LY294002, suggesting that the cytotoxic effect of photosensitized XL147 is facilitated by binding to PI3K in cells. In a single-cell illumination analysis using a fluorescent probe to identify reactive oxygen species (ROS), significantly increased ROS production was observed in the XL147-treated cells when the cell was illuminated with blue light. Taken together, it is conceivable that XL147, which is preferentially accumulated in cancer cells, could be photosensitized by blue light to produce ROS to kill cancer cells. This study will open up new possibilities for PDT using anticancer drugs. © 2016 UICC.

  17. A Laser Fabrication of Magnetic Micromachines by Using Optimized Photosensitive Ferrofluids

    Directory of Open Access Journals (Sweden)

    Ye Tian

    2016-01-01

    Full Text Available We report here a laser fabrication of magnetic micromachines by using optimized photosensitive ferrofluids. Fe3O4 nanoparticles were prepared by thermal decomposition and subsequent ligand exchange. And then, they were dispersed into photoresist. As a representative illustration, a magnetic microturbine with high surface flatness was fabricated, and its rotation speed could reach as high as 400 rpm under revolving magnetic field.

  18. Effective Single Photodynamic Treatment of ex Vivo Onychomycosis Using a Multifunctional Porphyrin Photosensitizer and Green Light

    OpenAIRE

    Hollander, Chelsea; Visser, Jasper; Haas, Ellen; Incrocci, Luca; Smijs, Threes

    2015-01-01

    Onychomycosis is predominantly caused by the dermatophytes Trichophyton rubrum, Trichophyton mentagrophytes and Trichophyton tonsurans. The main treatment obstacle concerns low nail-plate drug permeability. In vitro antifungal photodynamic treatment (PDT) and nail penetration enhancing effectiveness have been proven for multifunctional photosensitizer 5,10,15-tris(4-N-methylpyridinium)-20-(4-(butyramido-methylcysteinyl)-hydroxyphenyl)-[21H,23H]-porphine trichloride (PORTHE). This study invest...

  19. Caffeine metabolites not caffeine protect against riboflavin photosensitized oxidative damage related to skin and eye health

    DEFF Research Database (Denmark)

    Scurachio, R. S.; Mattiucci, F.; Santos, W. G.

    2016-01-01

    Caffeine metabolites were found to bind riboflavin with dissociation constant in the millimolar region by an exothermic process with positive entropy of reaction, which was found by 1H NMR and fluorescence spectroscopy to occur predominantly by hydrogen bonding with water being released from ribo...... singlet excited riboflavin through exothermic formation of ground-state precursor complexes indicating importance of hydrogen bounding through keto-enol tautomer's for protection of oxidizable substrates and sensitive structures against riboflavin photosensitization....

  20. Highly re-entrant profiles in a thick photosensitive material for nanotechnology applications

    Science.gov (United States)

    Flack, Warren W.; Nguyen, Ha-Ai; Shaw, Mark; do Canto, Manny

    2006-03-01

    The requirements for highly specialized photosensitive materials for nanotechnology and Micro-Electro-Mechanical Systems (MEMS) applications are being driven by the rapid growth of consumer products incorporating these devices. These high volume consumer devices including accelerometers for air-bag sensors, biomedical sensors, optical switches and ink jet print heads. These applications all require ultra-thick photosensitive materials with highly controllable lithographic properties. For ink-jet print head applications, the lithography requirements include the formation of high aspect ratio structures with a negative (re-entrant) profile for nozzle formation. In order to form the required nozzle geometry for high resolution ink-jet printers, photosensitive materials need to be capable of providing up to 10 degree negative profiles at a film thickness of up to 25 microns. For consistent print dot size it is necessary to maintain excellent control and repeatability of the sidewall angle of the nozzle. Since this material remains on the substrate as a permanent part of the ink-jet print head, the mechanical and adhesive properties of the material are as important as the lithographic properties. This paper investigates modifications to an existing MicroChem epoxy-based SU8-4000 thick photoresist to generate highly re-entrant sidewall angles for next-generation high resolution ink-jet nozzle formation. Multiple versions of SU8-4000 with different levels of dye tuned for the exposure wavelength are exposed using a 1X lithography system optimized for thick photoresist processing. This stepper uses a combination of low numerical aperture, broadband exposure and large focus offsets for optimal processing of thick photosensitive materials. Basic photoresist characterization techniques in conjunction with cross sectional SEM analysis are used to establish lithographic capabilities for nozzle formation.

  1. Stereo- and regio-selectivity in the photosensitized dimerization of 1, 3-dimethylthymine in solution

    Institute of Scientific and Technical Information of China (English)

    HEI Xiaoming; SONG Qinhua; TANG Wenjian; WANG Hongbo; GUO Qingxiang; YU Shuqin

    2005-01-01

    The effects of reaction pathway and temperature on stereo- and regio-selectivity of photocycloaddition of 1, 3-dimethylthymine (DMT) which gives four cyclobutane type dimers in solution using acetone as the photosensitizer, are investigated by measuring the product distribution. It is demonstrated that the ground-state aggregation between DMT molecules mainly leads to (h-t)dimers, and the diffusion-controlled triplet dimerization is favorable to the formation of (h-h) dimers.

  2. Photosensitivity control of an isotropic medium through polarization of light pulses with tilted intensity front.

    Science.gov (United States)

    Kazansky, Peter G; Shimotsuma, Yasuhiko; Sakakura, Masaaki; Beresna, Martynas; Gecevičius, Mindaugas; Svirko, Yuri; Akturk, Selcuk; Qiu, Jianrong; Miura, Kiyotaka; Hirao, Kazuyuki

    2011-10-10

    We present the first experimental evidence of anisotropic photosensitivity of an isotropic homogeneous medium under uniform illumination. Our experiments reveal fundamentally new type of light induced anisotropy originated from the hidden asymmetry of pulsed light beam with a finite tilt of intensity front. We anticipate that the observed phenomenon, which enables employing mutual orientation of a light polarization plane and pulse front tilt to control interaction of matter with ultrashort light pulses, will open new opportunities in material processing.

  3. Photosensitive seizures provoked while viewing "pocket monsters," a made-for-television animation program in Japan.

    Science.gov (United States)

    Ishida, S; Yamashita, Y; Matsuishi, T; Ohshima, M; Ohshima, H; Kato, H; Maeda, H

    1998-12-01

    To describe the recent epidemic of photosensitive seizure that occurred in relation to an episode of the television animation program "Pocket Monsters," we report four patients who experienced seizures while watching the episode in question. We also report some technical aspects of the program episode. We investigated the clinical symptoms of the four patients and performed routine EEGs with intermittent photic stimulation (IPS). If IPS provoked no photoparoxysmal response (PPR) during the routine EEG examination, a second EEG was performed with the photic stimulator placed 10 cm from the patient's eyes. In addition, we reviewed the "Pocket Monsters" episode, focusing our attention on the visual techniques used with reference to the Independent Television Commission (ITC) guidelines. One patient who had myoclonic jerks before the convulsion in question was diagnosed as having juvenile myoclonic epilepsy, and the diagnosis of another patient was pure photosensitive epilepsy. The remaining two patients had their first seizures, which could be occasional seizures, and we therefore could not reach a diagnosis of epilepsy. In our four patients, only one showed PPR on the routine EEG. Two patients revealed PPR on the second EEG, and the remaining patient showed no PPR. Rapid changes in color are believed to be responsible for the photosensitive seizures because all four patients had seizures at around 18:50, when seconds of deep red and bright blue flashes, alternating at a frequency of 12 Hz, were shown. Regulations for technical aspects of children's programming, including the use of colors, are urgently needed in Japan to prevent a repeated incident. In addition, the IPS procedure needs to be standardized, especially for patients who are suspected to have photosensitivity.

  4. Photosensitized cis/trans isomerization of 1-(1-propenyl)cycloalkenes

    Energy Technology Data Exchange (ETDEWEB)

    Inman, W.D.; Sanchez, K.A.J.; Chaidez, M.A.; Paulson, D.R. (California State Univ., Los Angeles (USA))

    1989-09-29

    The photosensitized cis/trans isomerization of a series of 1-(1-propenyl)cycloalkenes is reported. A plot of the photostationary state trans/cis ratio vs the sensitizer triplet energy for 1-(1-propenyl)cyclopentene shows a constant trans/cis ratio of {approx} 1.0 with high-energy sensitizers (E{sub T} > 61 kcal/mol). The plot shows one maxima at E{sub T} {approx} 55 kcal/mol with low-energy sensitizers (E{sub T} < 61 kcal/mol). This type of plot is very similar to those obtained with acyclic dienes such as piperylene. The 1-(1-propenyl)cyclohexene system shows a similar plot with high-energy sensitizers, but with low-energy sensitizers this system shows two maxima occurring at 56 and 47 kcal/mol, respectively. This double-maxima plot is rationalized by an unusually low trans/cis decay ratio for the s-cis relaxed triplet state of the 1-(1-propenyl)cyclohexene system. This double maxima is not observed in other diene systems due to a high trans/cis decay ratio for their s-cis relaxed triplet states. The photosensitized cis/trans isomerization of 2-ethylidene-10-methyl-1(9)-octalin was also studied as a model for a conformationally locked s-trans system. The 1-(1-propenyl)cycloheptene system undergoes photosensitized cis/trans isomerization, but photostationary cis/trans isomerization data could not be obtained due to a very efficient photosensitized dimerization of this diene system.

  5. PEG-Phospholipids Coated Quantum Rods as Amplifiers of the Photosensitization Process by FRET.

    Science.gov (United States)

    Timor, Reut; Weitman, Hana; Waiskopf, Nir; Banin, Uri; Ehrenberg, Benjamin

    2015-09-30

    Singlet oxygen ((1)O2) generated upon photostimulation of photosensitizer molecules is a highly reactive specie which is utilized in photodynamic therapy. Recent studies have shown that semiconductor nanoparticles can be used as donors in fluorescence resonance energy transfer (FRET) process to excite attached photosensitizer molecules. In these studies, their unique properties, such as low nanoscale size, long-term photostability, wide broad absorbance band, large absorption cross section, and narrow and tunable emission bands were used to provide advantages over the traditional methods to produce singlet oxygen. Previous studies that achieved this goal, however, showed some limitations, such as low FRET efficiency, poor colloidal stability, nonspecific interactions, and/or complex preparation procedure. In this work, we developed and characterized a novel system of semiconductor quantum rods (QRs) and the photosensitizer meso-tetra(hydroxyphenyl) chlorin (mTHPC), as a model system that produces singlet oxygen without these limitations. A simple two-step preparation method is shown; Hydrophobic CdSe/CdS QRs are solubilized in aqueous solutions by encapsulation with lecithin and PEGylated phospholipid (PEG-PL) of two lipid lengths: PEG350 or PEG2000. Then, the hydrophobic photosensitizer mTHPC, was intercalated into the new amphiphilic PEG-PL coating of the QR, providing a strong attachment to the nanoparticle without covalent linkage. These PEGylated QR (eQR)-mTHPC nanocomposites show efficient FRET processes upon light stimulation of the QR component which results in efficient production of singlet oxygen. The results demonstrate the potential for future use of this concept in photodynamic therapy schemes.

  6. Lipid composition affects the rate of photosensitized dissipation of cross-membrane diffusion potential on liposomes

    Science.gov (United States)

    Ytzhak, Shany; Wuskell, Joseph P.; Loew, Leslie M.; Ehrenberg, Benjamin

    2010-01-01

    Hydrophobic or amphiphilic tetrapyrrole sensitizers are taken up by cells and are usually located in cellular lipid membranes. Singlet oxygen is photogenerated by the sensitizer and it diffuses in the membrane and causes oxidative damage to membrane components. This damage can occur to membrane lipids and to membrane-localized proteins. Depolarization of the Nernst electric potential on cells’ membranes has been observed in cellular photosensitization, but it was not established whether lipid oxidation is a relevant factor leading to abolishing the resting potential of cells’ membranes and to their death. In this work we studied the effect of liposomes’ lipid composition on the kinetics of hematoporphyrin-photosensitized dissipation of K+-diffusion electric potential that was generated across the membranes. We employed an electrochromic voltage-sensitive spectroscopic probe that possesses a high fluorescence signal response to the potential. We found a correlation between the structure and unsaturation of lipids and the leakage of the membrane, following photosensitization. As the extent of non-conjugated unsaturation of the lipids is increased from 1 to 6 double bonds, the kinetics of depolarization become faster. We also found that the kinetics of depolarization is affected by the percentage of the unsaturated lipids in the liposome: as the fraction of the unsaturated lipids increases the leakage trough the membrane is enhanced. When liposomes are composed of a lipid mixture similar to that of natural membranes and photosensitization is being carried out under usual photodynamic therapy (PDT) conditions, photodamage to the lipids is not likely to cause enhanced permeability of ions through the membrane, which would have been a mechanism that leads to cell death. PMID:20536150

  7. Influence of Photosensitive Group Concentration on Birefringence Induced in Benzaldehyde Polymers

    Science.gov (United States)

    Mahilny, U. V.; Stankevich, A. I.; Trofimova, A. V.

    2014-01-01

    Induction of optical anisotropy in benzaldehyde polymer layers by linearly polarized UV radiation was investigated experimentally. Negative dichroism in absorption spectra and strong negative birefringence (-2 · 10-3) were related to the presence of an oriented ensemble of residual benzaldehyde groups. The thermal stability of photoinduced birefringence at high photosensitive group concentration was associated with a high density of photocross-links formed between macromolecules.

  8. Temperature dynamic models of heat exchanger for photosensitive material coating and drying processes; Kanko zairyo tofu kanso process ni okeru kucho system no ondo doteki model

    Energy Technology Data Exchange (ETDEWEB)

    Kido, K.; Sato, N.; Shimoji, M. [Konica Co. Ltd., Tokyo (Japan); Nakanishi, E. [Kobe University, Kobe (Japan). Faculty of Engineering

    1996-01-20

    Nonlinear and linear temperature dynamic models of a heat exchanger were investigated for air conditioning control of coating and drying processes for photosensitive materials. The nonlinear model was derived from heat balance based on the assumption of lumped parameter system that the heat exchanger is divided into small parts in the direction of flow (divided cell model). In each part, the temperature of the heating fluid, heated fluid and heat transfer tube with fin are assumed to be uniform. Parameters involved in this model were estimated from experimental data of the step response characteristics of temperature. The linear model is obtained by linearizing this nonlinear model. It was confirmed that the dynamic behavior of temperature can be successfully expressed by both nonlinear and linear models. Both models are considered to be utilizable for process analysis and control system design of the air conditioning system under consideration. 1 ref., 13 figs., 2 tabs.

  9. Intracellular reactive oxygen species in monocytes generated by photosensitive chromophores activated with blue light.

    Science.gov (United States)

    Bouillaguet, Serge; Owen, Brandi; Wataha, John C; Campo, Marino A; Lange, Norbert; Schrenzel, Jacques

    2008-08-01

    Disinfection of the tooth pulp-canal system is imperative to successful endodontic therapy. Yet, studies suggest that 30-50% of current endodontic treatments fail from residual bacterial infection. Photodynamic therapy using red-light chromophores (630 nm) to induce antimicrobial death mediated by generated reactive oxygen species (ROS) has been reported, but red-light also may thermally damage resident tissues. In the current study, we tested the hypothesis that several blue light chromophores (380-500 nm) generate intracellular reactive oxygen species but are not cytotoxic to mammalian cells. THP1 monocytes were exposed to 10 microM of four chromophores (chlorin e6, pheophorbide-a, pheophorbide-a-PLL, and riboflavin) for 30 min before activation with blue light (27J/cm(2), 60s). After activation, intracellular ROS were measured using a dihydrofluorescein diacetate technique, and cytotoxicity was determined by measuring mitochondrial activity with the MTT method. All photosensitizers produced intracellular ROS levels that were dependent on both the presence of the photosensitizer and blue light exposure. Riboflavin and pheophorbide-a-PLL produced the highest levels of ROS. Photosensitizers except riboflavin exhibited cytotoxicity above 10 microM, and all except pheophorbide-a-PLL were more cytotoxic after blue light irradiation. The current study demonstrated the possible utility of blue light chromophores as producers of ROS that would be useful for endodontic disinfection.

  10. Phototreatment of Water by Organic Photosensitizers and Comparison with Inorganic Semiconductors

    Directory of Open Access Journals (Sweden)

    Merlyn Thandu

    2015-01-01

    Full Text Available Phototreatment of water is drawing the attention of many as a promising alternative to replace methods like chlorination, ozonization, and other oxidation processes, used in current disinfection methods limiting harmful side-products and by-products that can cause damage to the fauna and flora. Porphyrins, phthalocyanines, and other related organic dyes are well known for their use in photodynamic therapy (PDT. These photosensitizers cause cell death by generating reactive oxygen species (ROS especially singlet oxygen in the presence of light. Such molecules are also being explored for photodynamically treating microbial infections, killing of unwanted pathogens in the environment, and oxidation of chemical pollutants. The process of photosensitisation (phototreatment can be applied for obtaining clean, microbe-free water, thus exploiting the versatile properties of photosensitizers. This review collects the various attempts carried out for phototreatment of water using organic photosensitizers. For comparison, some reports of semiconductors (especially TiO2 used in photocatalytic treatment of water are also mentioned.

  11. Enhancement in the photorefractive performance of organic composites photosensitized with functionalized CdSe quantum dots

    Science.gov (United States)

    Liang, Yichen; Wang, Wei; Moon, Jong-Sik; Winiarz, Jeffrey G.

    2016-08-01

    Enhancement in the photorefractive (PR) performance of organic composites photosensitized by CdSe quantum dots (QCdSe) passivated with the charge-transport ligands, sulfonated triphenyldiamine (STPD), is reported. This enhancement is primarily attributed to the ability of the passivating ligand, STPD, to facilitate the charge-transfer process between the QCdSe and the triphenyldiamine (TPD) charge-transport matrix. The PR composites exhibited a maximum photocharge-generation efficiency of 0.9% and two-beam coupling gain coefficient of 110 cm-1. These figures of merit represent a significant improvement over similar composites photosensitized with more conventional trioctylphosphine oxide-passivated QCdSe (TQCdSe). Moreover, composites photosensitized with SQCdSe had a faster response time of τ = 128 ms at an electric field of 60 V/μm compared with τ = 982 ms for those containing TQCdSe. Because of the molecular similarity between the STPD passivating groups and the TPD-based charge-transport matrix, concentrations of up to 1.4 wt% of SQCdSe are achieved in PR composites without any detectable phase separation, a considerable improvement over the 0.7 wt% for TQCdSe.

  12. Plasmonic photosensitization of a wide band gap semiconductor: converting plasmons to charge carriers.

    Science.gov (United States)

    Mubeen, Syed; Hernandez-Sosa, Gerardo; Moses, Daniel; Lee, Joun; Moskovits, Martin

    2011-12-14

    A fruitful paradigm in the development of low-cost and efficient photovoltaics is to dope or otherwise photosensitize wide band gap semiconductors in order to improve their light harvesting ability for light with sub-band-gap photon energies.(1-8) Here, we report significant photosensitization of TiO2 due to the direct injection by quantum tunneling of hot electrons produced in the decay of localized surface-plasmon polaritons excited in gold nanoparticles (AuNPs) embedded in the semiconductor (TiO2). Surface plasmon decay produces electron-hole pairs in the gold.(9-15) We propose that a significant fraction of these electrons tunnel into the semiconductor's conduction band resulting in a significant electron current in the TiO2 even when the device is illuminated with light with photon energies well below the semiconductor's band gap. Devices fabricated with (nonpercolating) multilayers of AuNPs in a TiO2 film produced over 1000-fold increase in photoconductance when illuminated at 600 nm over what TiO2 films devoid of AuNPs produced. The overall current resulting from illumination with visible light is ∼50% of the device current measured with UV (ℏω>Eg band gap) illumination. The above observations suggest that plasmonic nanostructures (which can be fabricated with absorption properties that cover the full solar spectrum) can function as a viable alternative to organic photosensitizers for photovoltaic and photodetection applications.

  13. Biodistribution, pharmacokinetic, and in-vivo fluorescence spectroscopic studies of photosensitizers

    Science.gov (United States)

    Moan, Johan; Peng, Qian; Iani, Vladimir; Ma, Li Wei; Horobin, Richard W.; Berg, Kristian; Kongshaug, Magne; Nesland, Jahn M.

    1996-01-01

    Some key data concerning the pharmacokinetics of PCT photosensitizers are reviewed. The following topics are discussed: The binding of photosensitizers to serum proteins, and the significance of LDL binding for tumor localization, the distribution of sensitizers among different tissue compartments and the significance of extracellular proteins and other stromal elements, such as macrophages, low tumor pH, leaky vasculature and poor lymphatic drainage for tumor selectivity of drugs, the retention and excretion of sensitizers, and intracellular pharmacokinetics. Furthermore, the usefulness of fluorescence measurements in the study of sensitizer pharmacokinetics is briefly discussed. A key observation is that 1O2 has a short radius of action. Since practically all PCT sensitizers act via the 1O2 pathway, only targets with significant sensitizer concentrations can be damaged. A given number of 1O2 entities generated in different organelles (mitochondria, lysosomes, plasma membrane, etc.) may lead to widely different effects with respect to cell inactivation. Similarly, sensitizers localizing in different compartments of tissues may have different photosensitizing efficiencies even under conditions of a similar 1O2 yield.

  14. Enhanced UV photosensitivity from rapid thermal annealed vertically aligned ZnO nanowires

    Directory of Open Access Journals (Sweden)

    Dhara Soumen

    2011-01-01

    Full Text Available Abstract We report on the major improvement in UV photosensitivity and faster photoresponse from vertically aligned ZnO nanowires (NWs by means of rapid thermal annealing (RTA. The ZnO NWs were grown by vapor-liquid-solid method and subsequently RTA treated at 700°C and 800°C for 120 s. The UV photosensitivity (photo-to-dark current ratio is 4.5 × 103 for the as-grown NWs and after RTA treatment it is enhanced by a factor of five. The photocurrent (PC spectra of the as-grown and RTA-treated NWs show a strong peak in the UV region and two other relatively weak peaks in the visible region. The photoresponse measurement shows a bi-exponential growth and bi-exponential decay of the PC from as-grown as well as RTA-treated ZnO NWs. The growth and decay time constants are reduced after the RTA treatment indicating a faster photoresponse. The dark current-voltage characteristics clearly show the presence of surface defects-related trap centers on the as-grown ZnO NWs and after RTA treatment it is significantly reduced. The RTA processing diminishes the surface defect-related trap centers and modifies the surface of the ZnO NWs, resulting in enhanced PC and faster photoresponse. These results demonstrated the effectiveness of RTA processing for achieving improved photosensitivity of ZnO NWs.

  15. Stability of isoflavone daidzein and genistein in riboflavin, chlorophyll b, or methylene blue photosensitization.

    Science.gov (United States)

    Yang, Seungok; Lee, Seungwook; Chung, Hyun; Lee, Jaehwan

    2008-03-01

    Effects of photosensitizers including riboflavin, chlorophyll b, or methylene blue on the stability of daidzein and genistein were studied in model systems by high-performance liquid chromatography (HPLC). Concentration of daidzein and genistein in 80% methanol with riboflavin under light for 7 h was significantly decreased with the apparent 1st-order rate constants of 0.234 and 0.193/h, respectively, (P 0.05). The stability of isoflavone aglycones in the dark did not change significantly irrespective of the presence of riboflavin (P > 0.05). The concentrations of daidzein and genistein in chlorophyll b or methylene blue model systems under light were not significantly different from those in the dark for 7 h (P > 0.05). Addition of sodium azide increased the stability of daidzein and genistein in riboflavin photosensitization with concentration dependent manner. However, the protective effects of beta-carotene addition on the photodegradation of isoflavones were not high. The stability difference of daidzein and genistein in riboflavin photosensitization may be due to the high reactivity of riboflavin through type I pathway, although singlet oxygen may be involved in part.

  16. Antimicrobial photodynamic therapy with two photosensitizers on two oral streptococci: an in vitro study

    Science.gov (United States)

    Vahabi, S.; Fekrazad, R.; Ayremlou, S.; Taheri, S.; Lizarelli, R. F. Z.; Kalhori, K. A. M.

    2011-12-01

    Periodontal diseases are caused by infection of tissues supporting the teeth due to complex aggregate of bacteria known as biofilm and firstly colonized by streptococci. The aim of this in vitro study was to evaluate the effect of Radachlorin® and Toluidine Blue O (TBO)-mediated photodynamic therapy (PDT) on the viability of two oral streptococci. Bacterial suspensions of Streptococcus mutans and Streptococcus sanguis were subjected to either TBO or Radachlorin®, Then exposed to two different diode laser light at energy densities of 3, 6 J/cm2 at 633 nm and 6, 12 J/cm2 at 662 nm, respectively. The control groups were subjected to laser light alone, photosensitizer alone or received neither photosensitizer nor light exposure. The suspensions were then spread over specific agar mediums and viable microorganisms were counted after overnight incubation aerobically at 37°C, 5% CO2 and then reported as colony forming unit. The results indicated that photosensitization by the energy density of 6 J/cm2 with Radachlorin® and both 3 and 6 J/cm2 with TBO caused significant reduction in bacterial colony formation ( p oral streptococci in vitro.

  17. PEGylated Dendrimers as Drug Delivery Vehicles for the Photosensitizer Silicon Phthalocyanine Pc 4 for Candidal Infections.

    Science.gov (United States)

    Hutnick, Melanie A; Ahsanuddin, Sayeeda; Guan, Linna; Lam, Minh; Baron, Elma D; Pokorski, Jonathan K

    2017-02-13

    Fungi account for billions of infections worldwide. The second most prominent causative agent for fungal infections is Candida albicans (C. albicans). As strains of fungi become resistant to antifungal medications, new treatment modalities must be investigated to combat these infections. One approach is to employ photodynamic therapy (PDT). PDT utilizes a photosensitizer, light, and cellular O2 to produce reactive oxygen species (ROS), which then induce oxidative stress resulting in apoptosis. Silicon phthalocyanine Pc 4 is a photosensitizer that has exhibited success in clinical trials for a myriad of skin diseases. The hydrophobic nature of Pc 4, however, poses significant formulation and delivery challenges in the use of this therapy. To mitigate these concerns, a drug delivery vehicle was synthesized to better formulate Pc 4 into a viable PDT agent for treating fungal infections. Utilizing poly(amidoamine) dendrimers as the framework for the vehicle, ∼13% of the amine chain ends were PEGylated to promote water solubility and deter nonspecific adsorption. In vitro studies with C. albicans demonstrate that the potency of Pc 4 was not hindered by the dendrimer vehicle. Encapsulated Pc 4 was able to effectively generate ROS and obliterate fungal pathogens upon photoactivation. The results presented within describe a nanoparticulate delivery vehicle for Pc 4 that readily kills drug-resistant C. albicans and eliminates solvent toxicity, thus, improving formulation characteristics for the hydrophobic photosensitizer.

  18. Study of Photosensitive Dry Films Absorption for Printed Circuit Boards by Photoacoustic Technique

    Science.gov (United States)

    Hernández, R.; Zaragoza, J. A. Barrientos; Jiménez-Pérez, J. L.; Orea, A. Cruz; Correa-Pacheco, Z. N.

    2017-08-01

    In this work, the study of photosensitive dry-type films by photoacoustic technique is proposed. The dry film photoresist is resistant to chemical etching for printed circuit boards such as ferric chloride, sodium persulfate or ammonium, hydrochloric acid. It is capable of faithfully reproducing circuit pattern exposed to ultraviolet light (UV) through a negative. Once recorded, the uncured portion is removed with alkaline solution. It is possible to obtain good results in surface mount circuits with tracks of 5 mm. Furthermore, the solid resin films are formed by three layers, two protective layers and a UV-sensitive optical absorption layer in the range of 325 nm to 405 nm. By means of optical absorption of UV-visible rays emitted by a low-power Xe lamp, the films transform this energy into thermal waves generated by the absorption of optical radiation and subsequently no-radiative de-excitation occurs. The photoacoustic spectroscopy is a useful technique to measure the transmittance and absorption directly. In this study, the optical absorption spectra of the three layers of photosensitive dry-type films were obtained as a function of the wavelength, in order to have a knowledge of the absorber layer and the protective layers. These analyses will give us the physical properties of the photosensitive film, which are very important in curing the dry film for applications in printed circuit boards.

  19. Polymeric photosensitizer-embedded self-expanding metal stent for repeatable endoscopic photodynamic therapy of cholangiocarcinoma.

    Science.gov (United States)

    Bae, Byoung-chan; Yang, Su-Geun; Jeong, Seok; Lee, Don Haeng; Na, Kun; Kim, Joon Mee; Costamagna, Guido; Kozarek, Richard A; Isayama, Hiroyuki; Deviere, Jacques; Seo, Dong Wan; Nageshwar Reddy, D

    2014-10-01

    Photodynamic therapy (PDT) is a new therapeutic approach for the palliative treatment of malignant bile duct obstruction. In this study, we designed photosensitizer-embedded self-expanding nonvascular metal stent (PDT-stent) which allows repeatable photodynamic treatment of cholangiocarcinoma without systemic injection of photosensitizer. Polymeric photosensitizer (pullulan acetate-conjugated pheophorbide A; PPA) was incorporated in self-expanding nonvascular metal stent. Residence of PPA in the stent was estimated in buffer solution and subcutaneous implantation on mouse. Photodynamic activity of PDT-stent was evaluated through laserexposure on stent-layered tumor cell lines, HCT-116 tumor-xenograft mouse models and endoscopic intervention of PDT-stent on bile duct of mini pigs. Photo-fluorescence imaging of the PDT-stent demonstrated homogeneous embedding of polymeric Pheo-A (PPA) on stent membrane. PDT-stent sustained its photodynamic activities at least for 2 month. And which implies repeatable endoscopic PDT is possible after stent emplacement. The PDT-stent after light exposure successfully generated cytotoxic singlet oxygen in the surrounding tissues, inducing apoptotic degradation of tumor cells and regression of xenograft tumors on mouse models. Endoscopic biliary in-stent photodynamic treatments on minipigs also suggested the potential efficacy of PDT-stent on cholangiocarcinoma. In vivo and in vitro studies revealed our PDT-stent, allows repeatable endoscopic biliary PDT, has the potential for the combination therapy (stent plus PDT) of cholangiocarcinoma. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Gold Nanocage-Photosensitizer Conjugates for Dual-Modal Image-Guided Enhanced Photodynamic Therapy

    Science.gov (United States)

    Srivatsan, Avinash; Jenkins, Samir V.; Jeon, Mansik; Wu, Zhijin; Kim, Chulhong; Chen, Jingyi; Pandey, Ravindra K.

    2014-01-01

    We have demonstrated that gold nanocage-photosensitizer conjugates can enable dual image-guided delivery of photosensitizer and significantly improve the efficacy of photodynamic therapy in a murine model. The photosensitizer, 3-devinyl-3-(1'-hexyloxyethyl)pyropheophorbide (HPPH), was noncovalently entrapped in the poly(ethylene glycol) monolayer coated on the surface of gold nanocages. The conjugate is stable in saline solutions, while incubation in protein rich solutions leads to gradual unloading of the HPPH, which can be monitored optically by fluorescence and photoacoustic imaging. The slow nature of the release in turn results in an increase in accumulation of the drug within implanted tumors due to the passive delivery of gold nanocages. Furthermore, the conjugate is found to generate more therapeutic singlet oxygen and have a lower IC50 value than the free drug alone. Thus the conjugate shows significant suppression of tumor growth as compared to the free drug in vivo. Short-term study showed neither toxicity nor phenotypical changes in mice at therapeutic dose of the conjugates or even at 100-fold higher than therapeutic dose of gold nanocages. PMID:24465274

  1. Studies of a novel photosensitizer palladium-bacteriopheophorbide (Tookad) for the treatment of prostate cancer

    Science.gov (United States)

    Huang, Zheng; Chen, Qun; Brun, Pierre-Herve; Wilson, Brian C.; Scherz, Avigdor; Salomon, Yoram; Luck, David L.; Beckers, Jill; Hetzel, Fred W.

    2003-06-01

    In this study, photodynamic therapy (PDT) mediated with a novel, second generation photosensitizer Tookad (palladium-bacteriopheophorbide, WST09, STEBA Biotech, France), is investigated as an alternative modality in the treatment of prostate cancer. In vivo normal canine prostate and spontaneous advanced prostate cancer are used as the animal model. PDT was performed by irradiating the surgically exposed prostates with a diode laser (763 nm, 150 mW/cm) to activate the i.v. infused photosensitizer. The effects of drug concentration, drug-light interval, and light fluence rate on the PDT efficacy were studied. The prostates and adjacent tissues (bladder and underlying colon) were harvested and subjected to histopathological examination. During the one-week to 3-month period post PDT treatment, the dogs recovered well with little or no urethral complications. Prostatic urethra and prostate adjacent tissues (bladder and underlying colon) were well preserved. Light irradiation delivered during drug infusion or within 15 min post drug infusion induced the similar extend of damages. PDT induced prostate lesions in both normal and cancerous prostate were characterized by marked hemorrhagic necrosis and atrophy. Maximum lesion size of over 3 cm in dimension could be achieved with a single 1-cm interstitial treatment, suggesting the therapy is very effective in ablating cancerous prostatic tissue. In conclusion, the second generation photosensitizer Tookad mediated PDT may provide an effective alternative to treat prostate cancer.

  2. W-reactivation and W-mutagenesis in bacteriophages lambda and T7: comparison of action of ultraviolet irradiation (254nm) and furocouma photosensitization

    Energy Technology Data Exchange (ETDEWEB)

    Zavil' gel' skij, G.B.; Belogurov, A.A.; Kryuger, D.N. (AN SSSR, Moscow. Inst. Molekulyarnoj Biologii; Humboldt-Universitaet, Berlin (German Democratic Republic))

    1982-01-01

    When treating bacteriophage lambda with 8-methoxypsoralen (8-MOP) and light (lambda>320 nm), two types of photoproducts are formed in DNA: monoadducts and diadducts or interstrand linkings. If a wild-type strain of Escherichia coli is used as host, W-reactivation and W-mutagenesis (clear-mutation), approximately equal in magnitude to those of UV-irradiated phage lambda, are observed in the bacteriophage lambda treated with 8-MOP plus light. If mutant strains E coli uvrA/sup -/, recA/sup -/ and lexA/sup -/ are used as host W-reactivation and W-mutagenesis practically do not occur in phage lambda. Using the method of ''reirradiation'', it is shown that clear-mutations in 8-MOP plus light treated phage lambda are induced in the process of W-mutagenesis mainly due to the formation of diadducts (interstrand linking) in DNA. In the phage monoadducts of derived furocoumarins also have a mutageneous character but their mutagenesis effectiveness (mutation probability calculating on one photo product) is significantly inferior to that of diadducts (approximately 15-20 times). It has been demonstrated in the experiments on the determination of W-mutagenesis of phage lambda photosensitized with angelisine - an angular derivative of furocoumarins - that mainly form monoadducts in DNA. It is also shown that W-reactivation and W-mutagenesis effects are observed when sowing UV-irradiated (254 nm) phage lambda on E coli uvrA/sup -/ and wild-type strains treated with 8-MOP plus light. As to bacteriophage T7 treated with 8-MOP plus light, W-reactivation is not observed even on a wild strain E coli. Preliminary infection of cells with phage T7 that has been strongly inactivated using photosensitizer 8-MOP decreases repair's effectiveness of interstrand linkings in DNA of phage lambda.

  3. The in vitro photosensitivity of systemic lupus erythematosus skin fibroblasts.

    Science.gov (United States)

    Zamansky, G B; Minka, D F; Deal, C L; Hendricks, K

    1985-03-01

    To investigate the role of DNA damage in the pathogenesis of systemic lupus erythematosus (SLE), we studied the ability of skin fibroblasts derived from SLE patients to recover from ultraviolet (UV) light radiation of varying wavelengths. Four of five SLE cell strains were more sensitive to UV-C (254 nm), sun lamp, and UV-A (320 to 400 nm) light than were normal cells. SLE cellular recovery was most sensitive to broad spectrum, long wavelength light. This hypersensitivity did not appear to result from the UV light activation of a clastogenic factor. Experiments which examined the DNA repair capacity of irradiated cells indicated that SLE fibroblasts may be able to excise certain DNA lesions as well as normal cells. The mechanisms responsible for the hypersensitivity of SLE cells remain under investigation.

  4. Using Photosensitive Dye To Improve Multi Walled Carbon Nanotubes Dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Costanzo, Guadalupe; Goyanes, Silvia [Laboratorio de PolImeros y Materiales Compuestos, Dpto. de Fisica, FCEyN, Universidad de Buenos Aires (Argentina) (Argentina); Ledesma, Silvia, E-mail: ledesma@df.uba.ar [Laboratorio de Procesado de Imagenes, Dpto. de Fisica, FCEyN, Universidad de Buenos Aires (Argentina) (Argentina)

    2011-01-01

    As already well-known, the outstanding mechanical and electrical properties of carbon nanotubes (CNT) are partially lost when CNT aggregate. The fact that CNT tend to aggregate makes difficult to put them into a host matrix, for example. Until now, achieving stable dispersions of CNT is still a challenge. In the present work, we show that the addition of an azobenzene derivative, Disperse Orange 3 (DO3) to dispersions of multi walled carbon nanotubes (MWCNT) in the organic solvent tetrahydrofuran (THF) efficiently helps debundling MWCNT and makes dispersions stable for days. We report UV-Vis optical absorption experiments that suggest an interaction between MWCNT and DO3 molecules following the behavior qualitatively observed. Dispersions with MWCNT and DO3 in THF were observed qualitatively over time. Successful suspensions (for the higher DO3 concentrations studied) were stable for several days. Also, we prepared polymeric films doped with MWCNT non-covalent functionalized with DO3 in one of the proper DO3/MWCNT weight relation where stable supensions were obtained. In this study we show preliminary results where the optical response of these samples was also measured.

  5. Intratumor photosensitizer injection for photodynamic therapy: Pre-clinical experience with methylene blue, Pc 4, and Photofrin

    Science.gov (United States)

    Baran, Timothy M.; Foster, Thomas H.

    2016-03-01

    Intravenous administration of some photosensitizers, including the FDA-approved Photofrin, results in significant systemic photosensitivity and a 2-3-day drug-light interval. Direct intratumor injection of photosensitizer could potentially eliminate these negative aspects of photodynamic therapy (PDT), while requiring a lower photosensitizer dose to achieve comparable drug concentration in the target tissue. We performed PDT using intratumor injection of 3 photosensitizers, methylene blue (MB), Pc 4, and Photofrin, in mouse tumor models. After a 0-15 minute drug-light interval, illumination was delivered by appropriate diode lasers. For animals receiving MB or Pc 4, surface illumination was delivered using a microlens-terminated fiber. For animals receiving Photofrin, interstitial illumination was delivered by a 1 cm diffuser. In animals receiving MB or Pc 4, tumor dimensions were measured daily post-PDT, with a cure being defined as no palpable tumor 90 days post-treatment. For Photofrin, animals were sacrificed 24 hours post-PDT and tumors were excised, with samples HE stained to assess PDT-induced necrosis. 55% of tumors were cured with MB-PDT, and significant tumor growth delay (p=0.002) was observed for Pc 4. For Photofrin PDT, the mean necrosis radius was 3.4+/-0.8 mm, compared to 2.9+/-1.3 mm for systemic administration, which was not a significant difference (p=0.58). Intratumoral injection of the photosensitizers methylene blue, Pc 4, and Photofrin is feasible, and results in appreciable tumor response. Further investigation is necessary to optimize treatment protocols and assess the systemic photosensitivity induced by intratumor injection.

  6. Ultrasonic activation and chemical modification of photosensitizers enhances the effects of photodynamic therapy against Enterococcus faecalis root-canal isolates.

    Science.gov (United States)

    Tennert, C; Drews, A M; Walther, V; Altenburger, M J; Karygianni, L; Wrbas, K T; Hellwig, E; Al-Ahmad, A

    2015-06-01

    The aim of this study was to evaluate the effect of photodynamic therapy (PDT) on Enterococcus faecalis biofilms in artificially infected root canals using modified photosensitizers and passive ultrasonic activation. Two hundred and seventy extracted human teeth with one root canal were instrumented utilizing ProTaper files, autoclaved, infected with E. faecalis T9 for 72 h and divided into different groups: irrigation with 3% sodium hypochlorite (NaOCl), 20% ethylenediaminetetraacetic acid (EDTA), or 20% citric acid, PDT without irrigation, PDT accompanied by irrigation with NaOCl, EDTA, or citric acid, PDT using an EDTA-based photosensitizer or a citric-acid-based photosensitizer and PDT with ultrasonic activation of the photosensitizer. A 15 mg/ml toluidine blue served as the photosensitizer, activated by a 100 mW LED light source. Sterile paper points were used for sampling the root canals and dentin chips were collected to assess the remaining contamination after treatment. Samples were cultured on blood agar plates and colony forming units were quantified. PDT alone achieved a reduction in E. faecalis counts by 92.7%, NaOCl irrigation alone and combined with PDT by 99.9%. The antibacterial effects increased by the combination of irrigation using EDTA or citric acid and PDT compared to irrigation alone. More than 99% of E. faecalis were killed using PDT with the modified photosensitizers and ultrasonic activation. NaOCl based disinfection achieved the highest antimicrobial effect. Using PDT with an EDTA-based or citric-acid-based phozosensitizer or activating the photosensitizer with ultrasound resulted in a significantly higher reduction in E. faecalis counts compared to conventional PDT. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Chlorophyll derivatives for pest and disease control: Are they safe?

    Energy Technology Data Exchange (ETDEWEB)

    Azizullah, Azizullah, E-mail: azizswabi@gmail.com; Murad, Waheed

    2015-01-15

    Chlorophyll derivatives are getting widespread acceptance among the researchers as natural photosensitizers for photodynamic control of pests and disease vectors; however, rare attention has been given to evaluation of their toxicity to non-target organisms in the environment. This perspective article highlights that chlorophyll derivatives may not be as safe as believed and can possibly pose risk to non-target organisms in the environment. We invite the attention of environmental biologists, particularly ecotoxicologists, to contribute their role in making the application of chlorophyll derivatives more environmentally friendly and publicly acceptable.

  8. Spectral- and time-resolved phosphorescence of photosensitizers and singlet oxygen: From in vitro towards in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Vyklický, Vojtěch [Charles University in Prague, Faculty of Mathematics and Physics, Department of Chemical Physics and Optics, Ke Karlovu 3, 121 16 Praha 2 (Czech Republic); Dědic, Roman, E-mail: Roman.Dedic@mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, Department of Chemical Physics and Optics, Ke Karlovu 3, 121 16 Praha 2 (Czech Republic); Curkaniuk, Natalija [Charles University in Prague, Faculty of Mathematics and Physics, Department of Chemical Physics and Optics, Ke Karlovu 3, 121 16 Praha 2 (Czech Republic); Vilnius University, Faculty of Physics, Universiteto st. 3, LT-01513 Vilnius (Lithuania); Hála, Jan [Charles University in Prague, Faculty of Mathematics and Physics, Department of Chemical Physics and Optics, Ke Karlovu 3, 121 16 Praha 2 (Czech Republic)

    2013-11-15

    Spectral- and time-resolved infrared phosphorescence set-up was adapted for detection from surfaces of solid samples by utilizing fiber optics. Its abilities are demonstrated on the detection of singlet oxygen photosensitization by intrinsic (protoporphyrin IX synthesized from ALA) and extrinsic (TPPS{sub 4} and TMPyP) photosensitizers in in vitro layers of cultured 3T3 murine fibroblasts and HeLa cells mimicking in vivo tissues. Complex decays of phosphorescence of the photosensitizers were detected. The data were approximated by multi-exponential decays, however, no straightforward explanation of the individual components was found. Singlet oxygen phosphorescence kinetics were obtained with rise-times corresponding to singlet oxygen lifetimes ranging from 0.7μs to 1.0μs and single-exponential decay times between 5.3μs and 6.5μs for different photosensitizers and cell lines. -- Highlights: ► Spectral- and time-resolved IR phosphorescence excited and collected by lightguides. ► Detection of singlet oxygen photosensitization in in vitro layers of cultured cells. ► Complex decays of PS phosphorescence approximated by multi-exponential decays. ► Singlet oxygen life-times ranging from 0.7μs to 1.0μs. ► Singlet oxygen exponential decay times 5.3–6.5μs for different PS and cell lines.

  9. Photoluminescence of cerium fluoride and cerium-doped lanthanum fluoride nanoparticles and investigation of energy transfer to photosensitizer molecules.

    Science.gov (United States)

    Cooper, Daniel R; Kudinov, Konstantin; Tyagi, Pooja; Hill, Colin K; Bradforth, Stephen E; Nadeau, Jay L

    2014-06-28

    CexLa1-xF3 nanoparticles have been proposed for use in nanoscintillator-photosensitizer systems, where excitation of nanoparticles by ionizing radiation would result in energy transfer to photosensitizer molecules, effectively combining the effects of radiotherapy and photodynamic therapy. Thus far, there have been few experimental investigations of such systems. This study reports novel synthesis methods for water-dispersible Ce0.1La0.9F3/LaF3 and CeF3/LaF3 core/shell nanoparticles and an investigation of energy transfer to photosensitizers. Unbound deuteroporphyrin IX 2,4-disulfonic acid was found to substantially quench the luminescence of large (>10 nm diameter) aminocaproic acid-stabilized nanoparticles at reasonable concentrations and loading amounts: up to 80% quenching at 6% w/w photosensitizer loading. Energy transfer was found to occur primarily through a cascade, with excitation of "regular" site Ce(3+) at 252 nm relayed to photosensitizer molecules at the nanoparticle surface through intermediate "perturbed" Ce(3+) sites. Smaller (<5 nm) citrate-stabilized nanoparticles were coated with the bisphosphonate alendronate, allowing covalent conjugation to chlorin e6 and resulting in static quenching of the nanoparticle luminescence: ∼50% at ∼0.44% w/w. These results provide insight into energy transfer mechanisms that may prove valuable for optimizing similar systems.

  10. Thermostable Eu(III)-nanorod luminophores with effective photosensitized energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Onodera, Hiromitsu [Laser Systems Inc, 1-4-1-10 Nijyuyonken, Nishi-ku, Sapporo, Hokkaido 063-0801 (Japan); Faculty School of Engineering, Hokkaido University, North-13 West-8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan); Nakajima, Ayako; Nakanishi, Takayuki; Fushimi, Koji [Faculty School of Engineering, Hokkaido University, North-13 West-8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan); Hasegawa, Yasuchika, E-mail: hasegaway@eng.hokudai.ac.jp [Faculty School of Engineering, Hokkaido University, North-13 West-8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan)

    2015-11-05

    The thermostable Eu(III)-doped nanorod aggregates composed of luminescent Eu(III) complexes and diphenylphosphinic acids (DPP) are reported. Prepared Eu(III)-nanorod aggregates [Eu(hfa){sub x}(TPPO){sub y}(DPP){sub z}]{sub n} (hfa: hexafluoroacetylacetionate, TPPO: triphenylphosphine oxide), Eu(III)-nanoparticle aggregates [Eu(hfa){sub x}(DPP){sub y}]{sub n}, and standard Eu(III)-nanoparticles [Eu(DPP){sub x}]{sub n} were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The decomposition temperatures of [Eu(hfa){sub x}(DPP){sub y}]{sub n} and [Eu(hfa){sub x}(TPPO){sub y}(DPP){sub z}]{sub n} for thermogravimetric analysis (TGA) were found to be over > 500 °C. Photosensitized luminescence was successfully observed for Eu(III)-nanorod and Eu(III)-nanoparticle aggregates excited at the specific π–π* transition band for organic hfa ligands (λ = 340 nm), which is similar to the inter-ligand charge transfer (ILCT) band in the solid-state, were successfully observed. The photosensitized energy transfer efficiency of Eu(III)-nanorod aggregates of [Eu(hfa){sub x}(TPPO){sub y}(DPP){sub z}]{sub n} was estimated to be 91%. In this study, thermostable Eu(III)-nanorod aggregate luminophore composed of Eu(III) complexes and DPP joint compounds are demonstrated. - Graphical abstract: The thermostable Eu(III)-doped nanorod aggregates composed of luminescent Eu(III) complexes and diphenylphosphinic acids (DPP) are reported. Prepared Eu(III)-nanorod aggregates [Eu(hfa){sub x}(TPPO){sub y}(DPP){sub z}]{sub n} (hfa: hexafluoroacetylacetionate, TPPO: triphenylphosphine oxide), Eu(III)-nanoparticle aggregates [Eu(hfa){sub x}(DPP){sub y}]{sub n}, and standard Eu(III)-nanoparticles [Eu(DPP){sub x}]{sub n} were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The decomposition temperatures of [Eu(hfa){sub x}(DPP){sub y}]{sub n} and [Eu(hfa){sub x}(TPPO){sub y}(DPP){sub z}]{sub n} for

  11. Fabrication and characterization of photosensitive n-ZnO/p-InSe heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Kudrynskyi, Z., E-mail: kudrynskyi@gmail.com [Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Chernivtsi Branch, Str. I. Vilde 5, 58001 Chernivtsi (Ukraine); Khomyak, V. [Yuriy Fedkovich Chernivtsi National University, Str. Kotsubinsky 2, 58012 Chernivtsi (Ukraine); Katerynchuk, V.; Kovalyuk, M.; Netyaga, V.; Kushnir, B. [Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Chernivtsi Branch, Str. I. Vilde 5, 58001 Chernivtsi (Ukraine)

    2015-05-01

    Indium monochalcogenide (InSe) with a band gap of 1.25 eV is a promising material for photovoltaic applications. In this work, photosensitive anisotype n-ZnO/p-InSe heterojunctions were fabricated by means of radio-frequency magnetron sputtering of the zinc oxide onto freshly cleaved (0001) van der Waals surface of p-InSe single-crystal. Structural properties of the obtained heterostructures were investigated by means of X-ray diffraction. Surface morphology of the grown ZnO thin films was studied by means of atomic force microscopy. The electrical and photoelectrical properties of the heterojunctions were investigated using the current-voltage characteristics measured at different temperatures, capacitance-voltage characteristics and photoresponse spectra. The dominating current transport mechanisms through the heterojunctions under investigation were determined at forward and reverse biases. It was found that the developed heterojunctions n-ZnO/p-InSe show photosensitivity in the photon energy range (1.25-3.20 eV) at room temperature. In addition, we analyzed the influence of vacuum annealing of the heterojunctions at different temperatures on their photoelectric properties. - Highlights: • Thin ZnO films were grown onto van der Waals surface of InSe substrate. • n-ZnO/p-InSe heterojunctions were fabricated. • The heterojunctions are photosensitive in photon energy range from 1.12 to 3.75 eV. • Despite the lattice mismatch of 19% the heterojunctions exhibit diode-like behavior. • Vacuum annealing improves electrical properties of the heterojunctions.

  12. Evaluation of ALA-induced PpIX as a photosensitizer for PDT in cats

    Science.gov (United States)

    Lucroy, Michael D.; Edwards, Benjamin F.; Peavy, George M.; Krasieva, Tatiana B.; Griffey, Stephen M.; Madewell, Bruce R.

    1998-07-01

    Given exogenously, ALA defeats intrinsic regulatory feedback mechanisms allowing intracellular accumulation of protoporphyrin IX (PpIX), a highly efficient photosensitizer. In vivo, PpIX synthesis in neoplastic mammary tissues averages 20-fold higher than in normal mammary tissues. PpIX is retained intracellularly, unlike perivascular localization of other photosensitizers, and it is then cleared quickly from the body. In vitro, ALA induced PpIX production in our laboratory in 6 cell lines tested, including an established feline kidney cell line and dermal fibroblasts from primary skin biopsy explant, resulting in photosensitization. Fluorescent microscopy confirmed PpIX production in skin adnexae following ALA administration in a normal cat. To evaluate toxicity, three cats were treated with a single i.v. dose of ALA (either 100, 200, of 400 mg/kg) and followed for 7 days. Cats receiving 100 or 200 mg/kg ALA i.v. had elevated liver enzymes and bilirubin within 24 hours. Histopathology revealed hydropic changes in the liver and renal fibrosis. The cat receiving 400 mg/kg ALA intravenously had cutaneous flush, bradycardia and apnea associated with ALA administration; within 24 hours the cat was lethargic, anorectic and icteric. ALT, AST and bilirubin concentrations had increased significantly. At necropsy the liver had a prominent lobular pattern; histopathology revealed severe periportal hepatitis and splenic necrosis. Systemically administered ALA induces PpIX production, but toxicity may preclude its clinical application in the cat. PpIX levels seem to be more time dependent than those dependent at these three ALA doses and they are well beyond the saturation point for adequate PpIX conversion. The literature is scant regarding toxicity associated with parenteral administration of ALA.

  13. Photosensitive Shape Memory Polymer%光敏形状记忆聚合物

    Institute of Scientific and Technical Information of China (English)

    秦瑞丰; 朱光明; 杜宗罡; 周海峰

    2004-01-01

      The advances in photosensitive polymer and its shape memory effects are reviewed. The photoisomerization reaction of the photosensitive polymer and some factors that influence the shape memory effects, such as: the type of the Chromophore Group(CG),the chain structure of the polymer, the content of the CG, the position of the CG and the phase state of the polymer, are introduced. A novel photosensitive shape memory polymer, Liquid-Crystalline Elastomer is also introduced.%  综述了光敏形状记忆聚合物的研究进展。主要关注了结构和形状记忆效应之间的关系。光敏形状记忆聚合物的形状记忆效应主要与聚合物的链结构、生色团的种类、生色团的含量、生色团的位置及聚合物体系所处的相态等因素有关。分别介绍了生色团位于聚合物侧链的光敏形状记忆聚合物、生色团位于主链的光敏形状记忆聚合物以及含生色团的有机小分子和聚合物经共混制得的光敏形状记忆聚合物体系。另外还介绍了一种新的光敏形状记忆聚合物体系,液晶弹性体。

  14. On the factors influencing the performance of solar reactors for water disinfection with photosensitized singlet oxygen.

    Science.gov (United States)

    Manjón, Francisco; Villén, Laura; García-Fresnadillo, David; Orellana, Guillermo

    2008-01-01

    Two solar reactors based on compound parabolic collectors (CPCs) were optimized for water disinfection by photosensitized singlet oxygen (1O2) production in the heterogeneous phase. Sensitizing materials containing Ru(II) complexes immobilized on porous silicone were produced, photochemically characterized, and successfully tested for the inactivation of up to 10(4) CFU mL(-1) of waterborne Escherichia coli (gram-negative) or Enterococcus faecalis (gram-positive) bacteria. The main factors determining the performance of the solar reactors are the type of photosensitizing material, the sensitizer loading, the CPC collector geometry (fin- vs coaxial-type), the fluid rheology, and the balance between concurrent photothermal--photolytic and 1O2 effects on the microorganisms' inactivation. In this way, at the 40 degrees N latitude of Spain, water can be disinfected on a sunny day (0.6-0.8 MJ m(-2) L(-1) accumulated solar radiation dose in the 360-700 nm range, typically 5-6 h of sunlight) with a fin-type reactor containing 0.6 m2 of photosensitizing material saturated with tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (ca. 2.0 g m(-2)). The optimum rheological conditions require laminar-to-transitional water flow in both prototypes. The fin-type system showed better inactivation efficiency than the coaxial reactor due to a more important photolytic contribution. The durability of the sensitizing materials was tested and the operational lifetime of the photocatalyst is at least three months without any reduction in the bacteria inactivation efficiency. Solar water disinfection with 1O2-generating films is demonstrated to be an effective technique for use in isolated regions of developing countries with high yearly average sunshine.

  15. Effects of some heavy metals on the action potentials of an identified Helix pomatia photosensitive neuron.

    Science.gov (United States)

    Kartelija, Gordana; Radenović, Lidija; Todorović, Natasa; Nedeljković, Miodrag

    2005-06-01

    In the photosensitive MB neuron in the left parietal ganglion of Helix pomatia, the onset of light prolongs significantly (by about 40%) the duration of the action potential. The broadening of the action potential after the onset of light was found to be due to its calcium component and could not be induced after blocking Ca(2+) channels by Cd(2+) and Pb(2+) and in absence of Ca(2+) in medium. The blocking effect of both compounds was reversible. It was found that CdCl(2) exhibited a more intense blocking effect than PbCl(2).

  16. Increase of the photosensitivity of undoped poly(methylmethacrylate) under UV radiation at 325 nm

    DEFF Research Database (Denmark)

    Sáez-Rodríguez, D.; Nielsen, Kristian; Bang, Ole;

    2014-01-01

    In this paper we report, for the first time to our knowledge, an increase of the photosensitivity of a microstructured polymer optical fibre (mPOF) made of undoped PMMA due to applied strain during the fabrication of the gratings. In the work, fibre Bragg gratings (FBGs) have been fabricated...... in undoped PMMA mPOFs with a hexagonal structure of three rings in the inner cladding. Two sets of FBGs were inscribed at two different resonant wavelengths (827 nm and 1562 nm) at different strains using an UV He-Cd laser at 325 nm focused by a lens and scanned over the fibre. We observed an increase...

  17. Protein profiles of Escherichia coli and Staphylococcus warneri are altered by photosensitization with cationic porphyrins.

    Science.gov (United States)

    Alves, Eliana; Esteves, Ana Cristina; Correia, António; Cunha, Ângela; Faustino, Maria A F; Neves, Maria G P M S; Almeida, Adelaide

    2015-06-01

    Oxidative stress induced by photodynamic treatment of microbial cells causes irreversible damages to vital cellular components such as proteins. Photodynamic inactivation (PDI) of bacteria, a promising therapeutic approach for the treatment of superficial and localized skin and oral infections, can be achieved by exciting a photosensitizing agent with visible light in an oxygenated environment. Although some studies have addressed the oxidative alterations of PDI in bacterial proteins, the present study is the first to compare the electrophoretic profiles of proteins of Gram-positive and Gram-negative bacteria, having two structurally different porphyrins, with different kinetics of photoinactivation. The cationic porphyrins 5,10,15-tris(1-methylpyridinium-4-yl)-20-(pentafluorophenyl)porphyrin tri-iodide (Tri-Py(+)-Me-PF) and 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin tetra-iodide (Tetra-Py(+)-Me) were used to photosensitize Escherichia coli and Staphylococcus warneri upon white light irradiation at an irradiance of 4.0 mW cm(-2). After different photosensitization periods, proteins were extracted from bacteria and analyzed using one-dimensional SDS-PAGE. Apparent molecular weights and band intensities were determined after an irradiation period corresponding to a reduction of 4 log10 in cell viability. After photodynamic treatment, there was a general loss of bacterial proteins, assigned to large-scale protein degradation. Protein loss was more pronounced after PDI with Tri-Py(+)-Me-PF in both bacteria. There was also an increase in the concentration of some proteins as well as an increase in the molecular weight of other proteins. We show that proteins of E. coli and S. warneri are important targets of PDI. Although there is an attempt of cellular response to the PDI-induced damage by overexpression of a limited number of proteins, the damage is lethal. Our results show that changes occurring in the protein pattern during photodynamic treatment are

  18. Nanodiamonds + bacteriochlorin as an infrared photosensitizer for deep-lying tumor diagnostics and therapy

    Science.gov (United States)

    Sharova, A. S.; Maklygina, YU S.; Lisichkin, G. V.; Mingalev, P. G.; Loschenov, V. B.

    2016-08-01

    The spectroscopic properties of potentially perspective nanostructure: diamond nanoparticles with a surface layer of IR-photosensitizer, bacteriochlorin, were experimentally investigated in this study. Such specific structure of the object encourages enhancement of the drug tropism to the tumor, as well as increasing of photodynamic penetration depth. The size distribution spectra of diamond nanoparticles; diamond nanoparticles, artificially covered with bacteriochlorin molecules layer, in aqueous solution, were obtained during the study. Based on the absorption and fluorescence spectra analysis, the benefits of functional nanostructure as a drug for deep-lying tumor diagnostics and therapy were reviewed.

  19. Organic photosensitive cells having a reciprocal-carrier exciton blocking layer

    Science.gov (United States)

    Rand, Barry P.; Forrest, Stephen R.; Thompson, Mark E.

    2007-06-12

    A photosensitive cell includes an anode and a cathode; a donor-type organic material and an acceptor-type organic material forming a donor-acceptor junction connected between the anode and the cathode; and an exciton blocking layer connected between the acceptor-type organic material of the donor-acceptor junction and the cathode, the blocking layer consisting essentially of a material that has a hole mobility of at least 10.sup.-7 cm.sup.2/V-sec or higher, where a HOMO of the blocking layer is higher than or equal to a HOMO of the acceptor-type material.

  20. Generalized myoclonic epilepsy with photosensitivity in juvenile dogs caused by a defective DIRAS family GTPase 1

    Science.gov (United States)

    Wielaender, Franziska; Sarviaho, Riika; James, Fiona; Hytönen, Marjo K.; Cortez, Miguel A.; Kluger, Gerhard; Koskinen, Lotta L. E.; Arumilli, Meharji; Kornberg, Marion; Bathen-Noethen, Andrea; Tipold, Andrea; Rentmeister, Kai; Bhatti, Sofie F. M.; Hülsmeyer, Velia; Boettcher, Irene C.; Tästensen, Carina; Flegel, Thomas; Leeb, Tosso; Matiasek, Kaspar; Fischer, Andrea; Lohi, Hannes

    2017-01-01

    The clinical and electroencephalographic features of a canine generalized myoclonic epilepsy with photosensitivity and onset in young Rhodesian Ridgeback dogs (6 wk to 18 mo) are described. A fully penetrant recessive 4-bp deletion was identified in the DIRAS family GTPase 1 (DIRAS1) gene with an altered expression pattern of DIRAS1 protein in the affected brain. This neuronal DIRAS1 gene with a proposed role in cholinergic transmission provides not only a candidate for human myoclonic epilepsy but also insights into the disease etiology, while establishing a spontaneous model for future intervention studies and functional characterization. PMID:28223533

  1. Strong Memory in Time Series of Human Magnetoencephalograms Can Identify Photosensitive Epilepsy

    CERN Document Server

    Yulmetyev, R M; Hänggi, P; Khusaenova, E V; Shimojo, S; Yulmetyeva, D G

    2006-01-01

    o discuss the salient role of the statistical memory effects in the human brain functioning we have analyzed a set of stochastic memory quantifiers that reflects the dynamical characteristics of neuromagnetic brain responses to a flickering stimulus of different color combinations from a group of control subjects which is contrasted with those from a patient with photosensitive epilepsy (PSE). We have discovered the emergence of strong memory and the accompanying transition to a regular and robust regime of chaotic behavior of the signals in the separate areas for a patient with PSE. This finding most likely identifies the regions of the location the protective mechanism in a human organism against occurrence of PSE.

  2. Gratings, photosensitivity, and poling in silica optical waveguides with 157-nm fluorine laser radiation

    Science.gov (United States)

    Chen, Peng (Kevin)

    2002-08-01

    The energetic 7.9-eV photons of the F2 laser directly access bandgap states in germanosilicate glasses to drive one-photon processes for inducing strong refractive index changes in silica optical waveguides. In this thesis, the author carried out the first comprehensive F2-laser photosensitivity studies with an aim to assess prospects for shaping useful photonic structures directly inside the germanosilicate waveguides. Both planar waveguides and standard telecommunication fibers were examined. Large effective index change (>10-3) was induced in both fibers and planar waveguides without any enhancement technique. With the use of hydrogen loading enhancement, asymmetric refractive index profiles were noted by atomic force microscopy and microreflection microscopy, having a peak index change of larger than 0.01 in the fiber core. The 157-nm laser radiation is effective in rapidly forming long-period gratings in standard fibers. Grating formation is over 250 times faster than that with the 248-nm KrF laser constituting the fastest photosensitivity response ever reported. For planar lightwave circuits (PLCs), the 157-nm laser exposure generate narrow profiles of large index changes (Deltan ˜ 10 -2) that is useful in trimming phase errors and controlling birefringence in frequency domain modulators (FDMs) and interleavers. The large vacuum-ultraviolet-induced birefringence was used to completely compensate the intrinsic birefringence of Deltan ˜ 10-4 in typical PLCs. With hydrogen soaking, modest 157-nm pre-irradiation (accumulated fluence >3 J/cm2) was found to 'lock-in' a permanent photosensitivity enhancement in the germanosilica, permitting the formation of strong (40 dB) and stable fiber Bragg gratings with 248-nm-KrF laser light. The F2-laser photosensitivity locking was 300-time more effective than with KrF-laser pretreatment. The practical trimming applications in PLCs were demonstrated in PLC interleavers and FDMs. The 157-nm laser pre-radiation was found to

  3. Synthesis-characterization and photosensitivity of tetrakis-α-(2-methyl-8-quinolinoxy) metallophthalocyanines

    Institute of Scientific and Technical Information of China (English)

    Jinping XUE; Hong LIU; Changan FAN; Huming HONG; Naisheng CHEN; Jinling HUANG

    2008-01-01

    Four amphipathic cobalt(Ⅱ),nickel(Ⅱ),copper (Ⅱ),and zinc(Ⅱ) coordination compounds of tetrakis,α,(2,methyl,8,quinolinoxy)phthalocyanine are synthesized using "DBU catalytic method". The titled complexes are characterized by elemental analysis,mass spectra,UV,Vis,and IR spectra. In addition,the rates of photogenerated singlet oxygen and the rate constants of photodynamic oxidation of amino,acid substrate by the complexes are measured under the optical excitation at 670 nm,and the relations between their structures and their photosensitivities are discussed.

  4. Fabrication of microlens arrays in photosensitive glass by femtosecond laser direct writing

    Energy Technology Data Exchange (ETDEWEB)

    Lin, C.H. [National Cheng Kung University, Department of Engineering Science, Tainan (China); Missouri University of Science and Technology, Department of Mechanical and Aerospace Engineering, Rolla, MO (United States); Jiang, L. [Beijing Institute of Technology, Department of Mechanical and Automation Engineering, Beijing (China); Chai, Y.H. [Technology and Science Institute of Northern Taiwan, Department of Electrical Engineering, Taipei (China); Xiao, H. [Missouri University of Science and Technology, Department of Electrical and Computer Engineering, Rolla, MO (United States); Chen, S.J. [National Cheng Kung University, Department of Engineering Science, Tainan (China); Tsai, H.L. [Missouri University of Science and Technology, Department of Mechanical and Aerospace Engineering, Rolla, MO (United States)

    2009-12-15

    This article reports the fabrication of high-fill-factor plano-convex cylindrical and spherical microlens arrays horizontally and vertically embedded in a photosensitive Foturan glass chip by femtosecond (fs) laser micromachining. The microlens arrays were fabricated by modifying the microstructure of Foturan glass using fs laser direct writing followed by thermal treatment, wet etching, and additional annealing. The focusing ability and image quality of the microlens arrays were examined, showing that the lens arrays not only can focus light well but also provide an imaging capability that holds great potential for lab-on-a-chip applications. (orig.)

  5. Design and syntheses of MMP inhibitors and photosensitive lipid nanoparticle formulations for drug delivery

    Science.gov (United States)

    Subramaniam, Rajesh

    Drug administration without any compromise to the quality of life and lifespan is the ideal goal for disease management. The molecular mechanisms of several pathologies have shown that site-specific delivery of target-specific drugs seems to be a promising avenue to achieve this goal. This thesis describes the initial steps that we have taken toward that goal. Matrix metalloproteinases (MMPs) are a family of about 23 isozymes in humans that were actively targeted for treating a multitude of pathologies. Clinical studies carried out on cancer patients have revealed the complexity of the working of this enzyme family and necessitated the development of isozyme-specific MMP inhibitors. Our studies toward the development of isozyme-specific inhibitors have resulted in the development of several inhibitors that seem to be selective toward some MMP isozymes. Our understanding on the molecular mechanism that confers this selectivity is documented in this thesis. Another aspect of discussion in the thesis is the development of photosensitive liposomes for drug delivery that could be triggered to release the drug by irradiation with light of appropriate wavelength. Development of such delivery vehicles, in principle, would confer external spatiotemporal control on drug delivery. This could potentially lead to better disease management by minimizing side effects and enhancing patient compatibility. The thesis discusses our attempts toward the development of photosensitive liposomes. These liposomes incorporated a photosensitive lipid (PSL) that would be cleaved upon irradiation with UV light, causing liposomal destabilization and release of the enclosed drug. The discussion includes: (i) the syntheses of the PSLs, (ii) formulation of the photosensitive liposomes that contained a model drug, (iii) light-mediated release of the drug and (iv) the mechanism of photocleavage of the PSL that leads to content release from liposomes. The thesis concludes with suggestions toward the

  6. CdTe Quantum Dot/Dye Hybrid System as Photosensitizer for Photodynamic Therapy

    Directory of Open Access Journals (Sweden)

    Savateeva Diana

    2010-01-01

    Full Text Available Abstract We have studied the photodynamic properties of novel CdTe quantum dots—methylene blue hybrid photosensitizer. Absorption spectroscopy, photoluminescence spectroscopy, and fluorescence lifetime imaging of this system reveal efficient charge transfer between nanocrystals and the methylene blue dye. Near-infrared photoluminescence measurements provide evidence for an increased efficiency of singlet oxygen production by the methylene blue dye. In vitro studies on the growth of HepG2 and HeLa cancerous cells were also performed, they point toward an improvement in the cell kill efficiency for the methylene blue-semiconductor nanocrystals hybrid system.

  7. In vitro photostability and photosensitizing properties of bergamot oil. Effects of a cinnamate sunscreen.

    Science.gov (United States)

    Morlière, P; Hüppe, G; Averbeck, D; Young, A R; Santus, R; Dubertret, L

    1990-11-01

    Bergamottin, which accounts for about two-thirds of the absorption of UVA and UVB light by bergamot oil, is shown to be fairly unstable on UV irradiation of solutions of bergamot oil (in ethanol-water, 80:20 (w/w)). Bergamottin photodegradation is partly inhibited by molecular oxygen and also by a cinnamate sunscreen acting as a triplet excited state quencher. On UV irradiation of bergamot oil, type II photodynamic properties, i.e. singlet oxygen production, are observed, which can be mainly attributed to the excitation of bergamottin by light. Therefore bergamottin can be considered as a potential photosensitizer in the photobiological activity of bergamot oil.

  8. Riboflavin and chlorophyll as photosensitizers in electroformed giant unilamellar vesicles as food models

    DEFF Research Database (Denmark)

    Wang, Hui Jing; Liang, Ran; du, Hui Hui

    2017-01-01

    for hydrophilic riboflavin, while lipophilic chlorophyll a initiated GUV budding and subsequent disintegration under light irradiation, indicating that lipophilic photosensitizers are the more important in such structured lipids. Lipophilic β-carotene provided protection against oxidative damage induced...... by chlorophyll a as shown by an increased lag phase for budding; however, it had no effect on subsequent budding rate. Hydrophilic puerarin alone exhibited little protection in terms of lag phase, but decreased together with β-carotene budding rate after the lag phase by a factor of more than 2, showing a clear...

  9. Formation of cyclobutane thymine dimers from UVA photosensitization of pyridopsoralen monoadducted DNA

    Energy Technology Data Exchange (ETDEWEB)

    Guillo, L.A. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica; Beylot, B.; Spassky, A. [Paris-5 Univ., 75 (France); Vigny, P. [Centre de Biophysique Moleculaire, Orleans (France)

    1996-08-01

    The present report provides evidence that thymine dimerization can be UVA photosensitized at a tetranucleotide, 5`-TATT-3`, by a 7-methyl-pyrido(3,4-c)psoralen monoadduct in DNA. The efficiency of the photoprocess depends on the tetranucleotide flanking sequences. These results demonstrate that one DNA lesion can originate the contigious formation of a second type of lesion and emphasize the sequence-specific response to interaction of drugs with DNA. Results are related to the sensitivity of DNA to 1,10-phenanthroline-cuprous ion complex nucleolytic activity and discussed in terms of the major role of local deformability of DNA in interaction with ligands. (author).

  10. Spatially controlled synthesis of silver nanoparticles and nanowires by photosensitized reduction

    Energy Technology Data Exchange (ETDEWEB)

    Jradi, S; Zeng, X H; Plain, J; Royer, P; Bachelot, R; Akil, S [Laboratoire de Nanotechnologie et d' Instrumentation Optique, ICD CNRS FRE 2848, Universite de Technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes (France); Balan, L; Lougnot, D J; Soppera, O; Vidal, L, E-mail: lavinia.balan@uha.fr [Institut de Science des Materiaux de Mulhouse CNRS LRC 7228, 15 rue Jean Starcky, 68057 Mulhouse (France)

    2010-03-05

    The present paper reports on the spatially controlled synthesis of silver nanoparticles (NPs) and silver nanowires by photosensitized reduction. In a first approach, direct photogeneration of silver NPs at the end of an optical fiber was carried out. Control of both size and density of silver NPs was possible by changing the photonic conditions. In a further development, a photochemically assisted procedure allowing silver to be deposited at the surface of a polymer microtip was implemented. Finally, polymer tips terminated by silver nanowires were fabricated by simultaneous photopolymerization and silver photoreduction. The silver NPs were characterized by UV-visible spectroscopy and scanning electron microscopy.

  11. Fluorenyl porphyrins for combined two-photon excited fluorescence and photosensitization

    Science.gov (United States)

    Mongin, Olivier; Hugues, Vincent; Blanchard-Desce, Mireille; Merhi, Areej; Drouet, Samuel; Yao, Dandan; Paul-Roth, Christine

    2015-04-01

    The two-photon absorption (2PA), the luminescence and the photosensitization properties of porphyrin-cored fluorenyl dendrimers and meso-substituted fluorenylporphyrin monomer, dimer and trimer are described. In comparison with model tetraphenylporphyrin, these compounds combine enhanced (non-resonant) 2PA cross-sections in the near infrared and enhanced fluorescence quantum yields, together with maintained singlet oxygen generation quantum yields. 'Semi-disconnection' between fluorenyl groups and porphyrins (i.e. direct meso substitution) proved to be more efficient than non-conjugated systems (based on efficient FRET between fluorenyl antennae and porphyrins). These results are of interest for combined two-photon imaging and photodynamic therapy.

  12. CdTe Quantum Dot/Dye Hybrid System as Photosensitizer for Photodynamic Therapy

    Science.gov (United States)

    Rakovich, Aliaksandra; Savateeva, Diana; Rakovich, Tatsiana; Donegan, John F.; Rakovich, Yury P.; Kelly, Vincent; Lesnyak, Vladimir; Eychmüller, Alexander

    2010-04-01

    We have studied the photodynamic properties of novel CdTe quantum dots—methylene blue hybrid photosensitizer. Absorption spectroscopy, photoluminescence spectroscopy, and fluorescence lifetime imaging of this system reveal efficient charge transfer between nanocrystals and the methylene blue dye. Near-infrared photoluminescence measurements provide evidence for an increased efficiency of singlet oxygen production by the methylene blue dye. In vitro studies on the growth of HepG2 and HeLa cancerous cells were also performed, they point toward an improvement in the cell kill efficiency for the methylene blue-semiconductor nanocrystals hybrid system.

  13. Organic Aerosol Formation Photoenhanced by the Formation of Secondary Photo-sensitizers in ageing Aerosols

    Science.gov (United States)

    Aregahegn, Kifle; Nozière, Barbara; George, Christian

    2013-04-01

    Humankind is facing a changing environment possibly due to anthropogenic stress on the atmosphere. In this context, aerosols play a key role by affecting the radiative climate forcing, hydrological cycle, and by their adverse effect on health. The role of organic compounds in these processes is however still poorly understood because of their massive chemical complexity and numerous transformations. This is particularly true for Secondary Organic Aerosol (SOA), which are produced in the atmosphere by organic gases. Traditionally, the driving forces for SOA growth is believed to be the partitioning onto aerosol seeds of condensable gases, either emitted primarily or resulting from the gas phase oxidation of organic gases. However, even the most up-to-date models based on such mechanisms can not account for the SOA mass observed in the atmosphere, suggesting the existence of other, yet unknown formation processes. The present study shows experimental evidence that particulate phase chemistry produces photo-sensitizers that lead to photo-induced formation and growth of secondary organic aerosol in the near UV and the presence of volatile organic compounds (VOC) such as terpenes. By means of an aerosol flow tube reactor equipped with Scanning Mobility Particle Sizer (SMPS) having Kr-85 source aerosol neutralizer, Differential Mobility Analyser (DMA) and Condensation Particle Sizer (CPC), we identified that traces of the aerosol phase product of glyoxal chemistry as is explained in Gallway et al., and Yu et al., namely imidazole-2-carboxaldehyde (IC) is a strong photo-sensitizer when irradiated by near-UV in the presence of volatile organic compounds such as terpenes. Furthermore, the influence of pH, type and concentration of VOCs, composition of seed particles, relative humidity and irradiation intensity on particle growth were studied. This novel photo-sensitizer contributed to more than 30% of SOA growth in 19min irradiation time in the presence of terpenes in the

  14. THE PHOTOPOLYMERIZATION KINETICS OF PHOTOSENSITIZED ACRYLAMIDE SYSTEM INDUCED BY He-Ne LASER

    Institute of Scientific and Technical Information of China (English)

    FENG Minhui; LIANG Zhaoxi; CHEN Yonglie

    1991-01-01

    The kinetics of the photopolymerization of sensitized acrylamide (AM) system induced by He-Ne laser has been investigated. Using methylene blue (MB)-triethanolamine (TEOA) as the photosensitive system, the photopolymerization followed a nonsteady-state kinetic scheme in the initial period of polymerization (the monomer conversion C%<2%) and then followed a steady-state kinetic scheme (5%>C%>2%). According to the steady-state hypothesis, the mechanism of photopolymerization was proposed. The deduced kinetic equation of the photopolymerization of AM is in good coincidence with the experimental results.

  15. DFT-D investigation of the interaction between Ir (III) based photosensitizers and small silver clusters Ag{sub n} (n = 2–20, 92)

    Energy Technology Data Exchange (ETDEWEB)

    Bokareva, Olga S., E-mail: obokareva@gmail.com; Kühn, Oliver

    2014-05-19

    Highlights: • Dispersion effects in weakly bonded systems containing silver clusters are investigated. • Different dispersion models and their parametrizations are discussed. • Reparametrization of C{sub 6} coefficients for Ag and Ir is performed using MP2 and RPA as a reference. - Abstract: A dispersion-corrected density functional theory study of the photosensitizer [Ir(ppy){sub 2}(bpy)]{sup +} and its derivatives bound to silver clusters Ag{sub n} (n = 2–20, 92) is performed. The goal is to provide a new system-specific set of C{sub 6} interaction parameters for Ag and Ir atoms. To this end a QM:QM scheme is employed using the PBE functional and RPA as well as MP2 calculations as reference. The obtained C{sub 6} coefficients were applied to determine dissociation curves of selected IrPS–Ag{sub n} complexes and binding energies of derivatives containing oxygen and sulphur as heteroatoms in the ligands. Comparing different C{sub 6} parameters it is concluded that RPA-based dispersion correction produces binding energies close to standard D2 and D3 models, whereas MP2-derived parameters overestimate these energies.

  16. Comparative study of the phototoxicity of long-wavelength photosensitizers targeted by the MornigaG lectin.

    Science.gov (United States)

    Evangelio, Emi; Poiroux, Guillaume; Culerrier, Raphaël; Pratviel, Geneviève; Van Damme, Els J M; Peumans, Willy J; Barre, Annick; Rougé, Pierre; Benoist, Hervé; Pitié, Marguerite

    2011-07-20

    Morniga G is a plant lectin selective for high density of tumor-associated carbohydrate T and Tn antigens on the surface of cells. The interaction of the protein with Tn induces its cell penetration. This property was used for targeting photosensitizers (consisting of the porphyrins TrMPyP and TPPS, the Al(III)-phthalocyanin AlPcS(4), and the chlorin e6) against leukemic Jurkat T cells after covalent coupling to the protein. The control of MornigaG/photosensitizer loading allowed the comparison of the toxicity of the different photosensitizer conjugates. Conjugate including a single AlPcS(4) per protein appeared promising, since it is poorly toxic when irradiated under white light, while it shows a strong phototoxicity (LD(50) = 4 nM) when irradiated in the therapeutic window, it preferentially kills cancerous lymphocytes, and the sugar binding specificity of the lectin part of the molecule remains unaltered.

  17. Effect of variation in indium concentration on the photosensitivity of chlorine doped In2S3 thin films

    Science.gov (United States)

    Cherian, Angel Susan; Kartha, C. Sudha; Vijayakumar, K. P.

    2014-01-01

    Consequence of variation in Indium concentration in chlorine doped In2S3 thin films deposited by spray pyrolysis technique was studied. Chlorine was incorporated in the spray solution, using HCl and Indium concentration was varied by adjusting In/S ratio Interestingly, the photo response of all chlorine doped samples augmented compared to pristine samples; but the highest photosensitivity value of ˜2300 was obtained only when 36ml 0.5M HCl was added to the solution of In2S3 having In/S=2/8. It was also observed that samples with high photosensitivity possess higher band gap and variation in sub band gap absoption levels were observed with increase in Indium concentration. The present study proved that concentration of Indium plays an important role in controlling the crystallinity and photosensitivity of chlorine doped samples.

  18. Nano-formulation of a photosensitizer using a DNA tetrahedron and its potential for in vivo photodynamic therapy.

    Science.gov (United States)

    Kim, Kyoung-Ran; Bang, Duhee; Ahn, Dae-Ro

    2016-04-01

    Photodynamic therapy (PDT) is a cytotoxic treatment using singlet oxygen produced by photosensitizers. Approved porphyrinoid PDT still suffers from a lack of robust production methods and low water solubility. Methylene blue (MB) is a good candidate for the PDT drug, because the dye is an effective photosensitizer, can be easily synthesized, and is already being used in other clinical fields. However, its poor cell/tissue penetration and low stability against the reducible biological conditions should be addressed by using a proper delivery vehicle. Here, we employed a DNA tetrahedron, a self-assembled nanostructure as the carrier for intracellular delivery of MB by taking advantage of the DNA binding property of the photosensitizer and demonstrated photo-induced cytotoxicity by the MB delivered by the DNA nanocarrier. We also evaluated the PDT potency of the MB-loaded DNA nanoconstruct in vivo tumor model to suppress tumor growth.

  19. Urban biowaste-derived sensitizing materials for caffeine photodegradation.

    Science.gov (United States)

    Bianco Prevot, A; Baino, F; Fabbri, D; Franzoso, F; Magnacca, G; Nisticò, R; Arques, A

    2017-05-01

    Caffeine-photosensitized degradation has been studied in the presence of bio-based materials derived from urban biowaste after aerobic aging. A peculiar fraction (namely bio-based substances (BBSs)), soluble in all the pH range, has been used as photosensitizing agent. Several caffeine photodegradation tests have been performed, and positive results have been obtained in the presence of BBSs and H2O2, without and with additional Fe(II) (photo-Fenton-like process). Moreover, hybrid magnetite-BBS nanoparticles have been synthesized and characterized, in order to improve the sensitizer recovery and reuse after the caffeine degradation. In the presence of such nanoparticles and H2O2 and Fe(II), the complete caffeine degradation has been attained in very short time. Both homogeneous and heterogeneous processes were run at pH = 5, milder condition compared to the classic photo-Fenton process.

  20. Synergic phototoxic effect of visible light or Gallium-Arsenide laser in the presence of different photo-sensitizers on Porphyromonas gingivalis and Fusobacterium nucleatum

    Directory of Open Access Journals (Sweden)

    Habibollah Ghanbari

    2015-01-01

    Conclusion: Within the limitations of this study, the synergic phototoxic effect of visible light in combination with each of the photosensitizers on P. gingivalis and F. nucleatum. However, the synergic phototoxic effect of laser exposure and hydrogen peroxide and curcumin as photosensitizers on F. nucleatum was not shown.

  1. Polycrystalline BiFeO3 thin film synthesized via sol-gel assisted spin coating technique for photosensitive application

    Science.gov (United States)

    Bogle, K. A.; Narwade, R. D.; Phatangare, A. B.; Dahiwale, S. S.; Mahabole, M. P.; Khairnar, R. S.

    2016-05-01

    We are reporting photosensitivity property of BiFeO3 thin film under optical illumination. The thin film used for photosensitivity work was fabricated via sol-gel assisted spin coating technique. I-V measurements on the Cu/BiFeO3/Al structure under dark condition show a good rectifying property and show dramatic blue shit in threshold voltage under optical illumination. The microstructure, morphology and elemental analysis of the films were characterized by using XRD, UV-Vis, FTIR, SEM and EDS.

  2. Study of Photosensitivity as a Function of Polarization for UV-Light in Optical Fibre using Blue Luminescence

    DEFF Research Database (Denmark)

    Sørensen, Henrik Rokkjær; Canning, John; Gregersen, Niels

    2005-01-01

    The difference in photosensitivity between S and P polarized light is investigated. Polarisation dependent scattering at the fibre-air surface and UV-induced alignment are shown to be of no importance, but indications of radially parasitic defects sites are found.......The difference in photosensitivity between S and P polarized light is investigated. Polarisation dependent scattering at the fibre-air surface and UV-induced alignment are shown to be of no importance, but indications of radially parasitic defects sites are found....

  3. Preparation and characterization of highly photosensitive ZnO thin films

    Science.gov (United States)

    Jiménez González, Antonio E.; Nair, P. K.

    1996-07-01

    Highly photosensitive ZnO films were prepared by the chemical technique Successive Ion Layer Adsorption and Reaction (SILAR). The films posses high optical transmittance (>90%) in the VIS and IR ranges. The cristallinity, orientation of the crystallites and surface morphology undergo changes with annealing. The optical transmittance and reflectance measurements indicated changes in the position of the optical absorption edge: shifting from 353 nm to 366 nm when annealed at 450 °C for 2 hours. The films are highly photosensitive, offering photocurrent to dark current ratio of 105, in as prepared films under 900 Wm-2 illumination from a solar simulator. Annealing in oxygen, hydrogen and vacuum improved the dark conductivity and the photoconductivity of the films. This effect is related to the modification of the defect statistics of the films and involves cation interstitials and anion vacancies. The studies indicate that the ZnO films prepared by the SILAR process may be used, with appropriated postdeposition treatments, for specific applications.

  4. Antimicrobial activity and cytotoxicity of 3 photosensitizers activated with blue light.

    Science.gov (United States)

    Bulit, Florence; Grad, Iwona; Manoil, Daniel; Simon, Stéphane; Wataha, John C; Filieri, Anna; Feki, Anis; Schrenzel, Jacques; Lange, Norbert; Bouillaguet, Serge

    2014-03-01

    Pulp repair is less likely to occur when dentin or pulpal tissue remains infected after caries excavation. Yet there are currently few options to kill residual bacteria without damaging resident cells. The current study has evaluated the effect of 3 blue light-activated chemicals on the viability of lactobacilli, odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD21), and human embryonic stem cells (hESC H1). Bacteria were incubated for 15 minutes with curcumin, eosin Y, or rose bengal and then irradiated with blue light (240 seconds). Bacteria were labeled with LIVE/DEAD BacLight Bacterial Viability kit, and viability was assessed by fluorescence-activated cell sorting. Cytotoxicity assays were performed on MDPC-23 cells, OD21, and hESC H1 cells grown in 24-well plates and exposed to the same photosensitizer-light combination. After 24 hours, cellular response was measured by using the methyl-thiazol-diphenyl-tetrazolium assay. Results were statistically analyzed by using one-way analysis of variance and Tukey multiple comparison intervals (α = 0.05). Bacterial viability was significantly reduced after exposure to different combinations of light and photosensitizers; mitochondrial activity of cultured cells remained unaffected when exposed to the same conditions, suggesting a good therapeutic index in vitro. Blue light-mediated disinfection is promising for the development of new treatment strategies designed to promote pulp repair after carious exposure. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  5. Chlorophyllin e4 is a novel photosensitizer against human bladder cancer cells.

    Science.gov (United States)

    Li, Bin; Wu, Zhiming; Li, Wenzhi; Jia, Guojin; Lu, Jiancheng; Fang, Jie; Chen, Gang

    2012-05-01

    The aim of the study was to investigate the photodynamic effect of the novel photosensitizer chlorophyllin e4 against human bladder cancer cells. T24 and 5637 bladder cancer cell lines were incubated with chlorophyllin e4 and irradiated with a 650-nm laser light. The controls included cells treated with chlorophyllin e4 but without light as well as cells exposed to laser light without chlorophyllin e4. Photocytotoxicity was monitored with MTT assay and apoptosis was measured by flow cytometry. In addition, confocal laser scanning microscopy was used to assess the subcellular localization of chlorophyllin e4. Chlorophyllin e4 exhibited significant photocytotoxicity in both T24 and 5637 cells, which resulted in a maximum of 82.43 and 85.06% cell death, respectively. Treatment with chlorophyllin e4 or laser light alone did not induce cytotoxicity. In addition, chlorophyllin e4-mediated PDT induced a significantly higher percentage of apoptosis in T24 and 5637 cells compared to the control groups (pchlorophyllin e4 co-localized with mitochondria in both cell lines. In conclusion, the remarkable photocytotoxicity, natural abundance and inexpensive composition of chlorophyllin e4 suggest that this compound may be a novel, effective photosensitizer for the treatment of human superficial bladder cancer.

  6. Photosensitization reaction induced hemolysis in a cuvette observed with hemoglobin absorption spectrum of various species

    Science.gov (United States)

    Hamada, Risa; Ogawa, Emiyu; Arai, Tsunenori

    2017-02-01

    To reveal hemolysis phenomena induced by a photosensitization reaction with its environment, we measured absorption spectrum of a blood sample to analyze hemoglobin oxidation and resolved oxygen desorption dynamics. The quartz glass cell with 1 mm optical path length was used as a cuvette. Red blood cell suspension medium of 0.625 hematocrit with 30 μg/ml talaporfin sodium was used as a sample. A red diode laser of 664 nm wavelength was emitted to the cuvette with 120 mW/cm2 in irradiance for 40 J/cm2. Absorption spectra of the sample were obtained before and after the photosensitization reaction by a spectrophotometer. Multiple regression analysis was employed to obtain concentrations of various hemoglobin species from measured absorption spectrum. Comparing to 0 and 40 J/cm2, methemoglobin and deoxygenated hemoglobin concentrations increased 0.19 g/dL and 0.02 g/dL, respectively. Oxygenated hemoglobin concentration decreased 0.17 g/dL. Oxygen environment could also be presented by oxygen pressure calculated from the concentrations of oxygenated hemoglobin and deoxygenated hemoglobin. These obtained hemoglobin concentration changes might indicate hemolysis progress and oxygen environment. We think this simple optical measurement could reveal both the hemolysis and oxygen environment.

  7. SuperNova, a monomeric photosensitizing fluorescent protein for chromophore-assisted light inactivation.

    Science.gov (United States)

    Takemoto, Kiwamu; Matsuda, Tomoki; Sakai, Naoki; Fu, Donald; Noda, Masanori; Uchiyama, Susumu; Kotera, Ippei; Arai, Yoshiyuki; Horiuchi, Masataka; Fukui, Kiichi; Ayabe, Tokiyoshi; Inagaki, Fuyuhiko; Suzuki, Hiroshi; Nagai, Takeharu

    2013-01-01

    Chromophore-assisted light inactivation (CALI) is a powerful technique for acute perturbation of biomolecules in a spatio-temporally defined manner in living specimen with reactive oxygen species (ROS). Whereas a chemical photosensitizer including fluorescein must be added to specimens exogenously and cannot be restricted to particular cells or sub-cellular compartments, a genetically-encoded photosensitizer, KillerRed, can be controlled in its expression by tissue specific promoters or subcellular localization tags. Despite of this superiority, KillerRed hasn't yet become a versatile tool because its dimerization tendency prevents fusion with proteins of interest. Here, we report the development of monomeric variant of KillerRed (SuperNova) by direct evolution using random mutagenesis. In contrast to KillerRed, SuperNova in fusion with target proteins shows proper localization. Furthermore, unlike KillerRed, SuperNova expression alone doesn't perturb mitotic cell division. Supernova retains the ability to generate ROS, and hence promote CALI-based functional analysis of target proteins overcoming the major drawbacks of KillerRed.

  8. Fluorescence Diagnosis of Damage to Tumor Tissues During Photodynamic Therapy with the Photosensitizer Photolon®

    Science.gov (United States)

    Samtsov, M. P.; Tarasau, D. S.; Kaplevsky, K. N.; Voropay, E. S.; Petrov, P. T.; Istomin, Yu. P.

    2016-03-01

    We have studied the feasibility of using an indotricarbocyanine dye as a marker for the efficacy of photodynamic therapy (PDT) of cancers with the photosensitizer Photolon®. We have established that on exposure to laser emission at λ = 667 nm with an exposure dose of 100 J/cm2, we observe that the Photolon® concentration drops by about a factor of two in the exposed part of the tumor, while the concentration of the indotricarbocyanine dye does not change in any region of the tumor node. We have observed a correlation between the change in the shape of the fluorescence spectra of the indotricarbocyanine dye in vivo in the 780-880 nm resulting from a PDT session with the photosensitizer Photolon® and the extent of damage to the tumor tissues. Changes in the shape of the fluorescence spectrum of the dye are interpreted in terms of a model involving the appearance of absorption by different forms of hemoglobin, and changes in their ratio in the exposed part of the tumor due to consumption of molecular oxygen.

  9. Photosensitivity and photoluminescence of Sn/Yb codoped silica optical fiber preform

    Institute of Scientific and Technical Information of China (English)

    Guanghui Chen; Yigang Li; Yaoji He; Liying Liu; Lei Xu; Wencheng Wang

    2009-01-01

    Sn/Yb codoped silica optical fiber preform is prepared by the modified chemical vapor deposition (MCVD) followed by the solution-doping method. Ultraviolet (UV) optical absorption, photoluminescence (PL) spectra under 978-nm laser diode (LD) pumping, and refractive index change after exposure to 266-nm laser pulses are obtained. There is only a little change in the PL spectra while a positive refractive index change up to 2×10-4 is observed after 30-min exposure to 266-nm laser pulses. The results show that both of the peculiar photosensitivity of Sn-doped silica and the gain property of Yb-doped silica fiber are preserved in the Sn/Yb codoped silica optical fiber preform. The experimental data suggest that the photosensitivity of the fiber preform under high energy density laser irradiation should be mainly due to the bond-breaking of oxygen deficient defects, while under relatively low energy density laser irradiation, the refractive index change probably originates from the photoconversion of optically active defects.

  10. Photosensitizer-Conjugated Human Serum Albumin Nanoparticles for Effective Photodynamic Therapy

    Directory of Open Access Journals (Sweden)

    Hayoung Jeong, MyungSook Huh, So Jin Lee, Heebeom Koo, Ick Chan Kwon, Seo Young Jeong, Kwangmeyung Kim

    2011-01-01

    Full Text Available Photodynamic therapy (PDT is an emerging theranostic modality for various cancers and diseases. The focus of this study was the development of tumor-targeting albumin nanoparticles containing photosensitizers for efficient PDT. To produce tumor-targeting albumin nanoparticles, the hydrophobic photosensitizer, chlorin e6 (Ce6, was chemically conjugated to human serum albumin (HSA. The conjugates formed self-assembled nanoparticle structures with an average diameter of 88 nm under aqueous conditions. As expected, the Ce6-conjugated HSA nanoparticles (Ce6-HSA-NPs were nontoxic in their native state, but upon illumination with the appropriate wavelength of light, they produced singlet oxygen and damaged target tumor cells in a cell culture system. Importantly, when the nanoparticles were injected through the tail vein into tumor-bearing HT-29 mice, Ce6-HSA-NPs compared with free Ce6 revealed enhanced tumor-specific biodistribution and successful therapeutic results following laser irradiation. These results suggest that highly tumor-specific albumin nanoparticles have the potential to serve not only as efficient therapeutic agents, but also as photodynamic imaging (PDI reagents in cancer treatment.

  11. Photosensitive diazotized poly(ethylene glycol) covalent capillary coatings for analysis of proteins by capillary electrophoresis.

    Science.gov (United States)

    Yu, Bing; Chen, Xin; Cong, Hailin; Shu, Xi; Peng, Qiaohong

    2016-09-01

    A new method for the fabrication of covalently cross-linked capillary coatings of poly(ethylene glycol) (PEG) is described using diazotized PEG (diazo-PEG) as a new photosensitive coating agent. The film of diazo-PEG depends on ionic bonding and was first prepared on the inner surface of capillary by self-assembly, and ionic bonding was converted into covalent bonding after reaction of ultraviolet light with diazo groups through unique photochemical reaction. The covalently bonded coating impedance adsorption of protein on the central surface of capillary and hence the four proteins ribonuclease A, cytochrome c, bovine serum albumin, and lysosome can be baseline separated by using capillary electrophoresis (CE). The covalently cross-linked diazo-PEG capillary column coatings not only improved the CE separation performance for proteins compared to non-covalently cross-linked coatings or bare capillary but also showed a remarkable chemical solidity and repeatability. Because photosensitive diazo-PEG took the place of the highly noxious and silane moisture-sensitive coating reagents in the fabrication of covalent coating, this technique shows the advantage of being environment-friendly and having a high efficiency for CE to make the covalently bonded capillaries.

  12. Targeted two-photon PDT photo-sensitizers for the treatment of subcutaneous tumors

    Science.gov (United States)

    Spangler, C. W.; Rebane, A.; Starkey, J.; Drobizhev, M.

    2009-06-01

    New porphyrin-based photo-sensitizers have been designed, synthesized and characterized that exhibit greatly enhanced intrinsic two-photon absorption. These new photo-sensitizers have been incorporated into triad formulations that also incorporate Near-infrared (NIR) imaging agents, and small-molecule targeting agents that direct the triads to cancerous tumors' over-expressed receptor sites. PDT can be initiated deep into the tissue transparency window at 780-800 nm utilizing a regeneratively amplified Ti:sapphire laser using 100-150 fs pulses of 600-800 mW. Human tumor xenografts of human breast cancer (MDA-MB-231) and both small SCLC (NCI-H69) and NSCLC (A-459) have been successfully treated using octreotate targeting of over-expressed SST2 receptors. In particular, the lung cancer xenografts can be successfully treated by irradiating from the side of the mouse opposite the implanted tumor, thereby passing through ca. 2 cm of mouse skin, tissue and organs with no discernible damage to healthy tissue while causing regression in the tumors. These results suggest a new PDT paradigm for the noninvasive treatment of subcutaneous tumors, including the possibility that the targeting moiety could be matched to individual patient genetic profiles (patient-specific therapeutics).

  13. Comparison of a new photosensitizer with erythrosine B in an AA/PVA-based photopolymer material.

    Science.gov (United States)

    Qi, Yue; Li, Haoyu; Fouassier, Jean Pierre; Lalevée, Jacques; Sheridan, John T

    2014-02-20

    Dyes often act as the photoinitiator PI/photosensitizer PS in photopolymer materials and are therefore of significant interest. The properties of the PI/PS used strongly influences grating formation when the material layer is exposed holographically. In this paper, the ability of a recently synthesized dye, D_1, to sensitize an acrylamide/polyvinyl alcohol (AA/PVA) based photopolymer is examined, and the material performance is characterized using an extended nonlocal photopolymerization-driven diffusion model. Electron spin resonance spin-trapping (ESR-ST) experiments are also carried out to characterize the generation of the initiator/primary radical, R(•), during exposure. The results obtained are then compared with those for the corresponding situation when using a xanthene dye, i.e., erythrosine B, under the same experiment conditions. The results indicate that the nonlocal effect is greater when this new photosensitizer is used in the material. Analysis indicates that this is the case because of the dye's (D_1) weak absorptivity and the resulting slow rate of primary radical production.

  14. Rheological characterization and turbidity of riboflavin-photosensitized changes in alginate/GDL systems.

    Science.gov (United States)

    Baldursdóttir, Stefanía G; Kjøniksen, Anna-Lena

    2005-04-01

    Riboflavin (RF) in combination with light, in the wavelength range of 310-800 nm, is used to induce degradation of alginic acid gels. Light irradiation of alginate solutions in the presence of RF under aerobic conditions causes scission of the polymer chains. In the development process of a new drug delivery system, RF photosensitized degradation of alginic acid gels is studied by monitoring changes in the turbidity and rheological parameters of alginate/glucono-delta-lactone (GDL) systems with different concentrations of GDL. Addition of GDL induces gel formation of the samples by gradually lowering the pH-value of the system. The turbidity is measured and the cloud point determined. The turbidity starts to increase after shorter times with enhanced concentration of GDL. Enhanced viscoelasticity is detected with increasing GDL concentration in the post-gel regime, but small differences are detected at the gel point. The incipient gel is 'soft' and has an open structure independent on the GDL concentration. In the post-gel regime solid-like behavior is observed, this is more distinct for the systems with high GDL concentrations. The effect of photosensitized RF on alginate/GDL systems decreases with increasing amount of GDL in the system. The same trend is detected whether the systems are irradiated in the pre-gel or in the post-gel regime.

  15. Voxel-based morphometry evaluation of patients with photosensitive juvenile myoclonic epilepsy.

    Science.gov (United States)

    Lin, Katia; Jackowski, Andrea Parolin; Carrete, Henrique; de Araújo Filho, Gerardo Maria; Silva, Henrique Hattori; Guaranha, Mirian Salvadori Bittar; Guilhoto, Laura Maria Figueiredo Ferreira; Bressan, Rodrigo Affonseca; Yacubian, Elza Márcia Targas

    2009-10-01

    We aim to investigate structural brain abnormalities in juvenile myoclonic epilepsy (JME) patients with photosensitivity (PS). Sixty JME patients, 19 (32%) of whom were photosensitive, were submitted to 1.5T magnetic resonance voxel-based morphometry (VBM). The control group (CTL) consisted of 30 sex-matched healthy volunteers. JME patients with (JME-PS) and without (JME-NPS) PS did not differ in their duration of disease, treatment or seizure control. VBM revealed significantly reduced bilateral gray matter volume (GMV) in thalami, insula cortices and cerebellar hemispheres; while significantly increased GMV was observed in the right superior frontal, orbitofrontal and medial frontal gyri of the JME group compared to CTL. JME-PS had reduced bilateral GMV of visual cortices when compared with CTL; while it was not seen among JME-NPS patients. Reduced left hippocampus and left inferior frontal gyrus volume was observed among JME-PS compared with JME-NPS. This study demonstrates structural abnormalities beyond the limits of the frontal lobes and provides evidence for the role of the occipital cortex in human PS, reinforcing the existence of functional-anatomic ictogenic networks in JME and the concept of 'system epilepsies'.

  16. Delivery of the photosensitizer Pc 4 in PEG-PCL micelles for in vitro PDT studies.

    Science.gov (United States)

    Master, Alyssa M; Rodriguez, Myriam E; Kenney, Malcolm E; Oleinick, Nancy L; Gupta, Anirban Sen

    2010-05-01

    The silicon phthalocyanine Pc 4 is a second-generation photosensitizer that has several properties superior to other photosensitizers currently approved by the FDA, and it has shown significant promise for photodynamic therapy (PDT) in several cancer cells in vitro and model tumor systems in vivo. However, because of the high hydrophobicity of Pc 4, its formulation for in vivo delivery and favorable biodistribution become challenging. To this end, we are studying encapsulation and delivery of Pc 4 in block copolymer micelles. Here, we report the development of biocompatible PEG-PCL micelle nanoparticles, encapsulation of Pc 4 within the micelle core by hydrophobic association with the PCL block, and in vitro PDT studies of the micelle-formulated Pc 4 in MCF-7c3 human breast cancer cells. Our studies demonstrate efficient encapsulation of Pc 4 in the micelles, intracellular uptake of the micelle-formulated Pc 4 in cells, and significant cytotoxic effect of the formulation upon photoirradiation. Quantitative estimation of the extent of Pc 4 loading in the micelles and the photocytotoxicity of the micelle-incorporated Pc 4 demonstrate the promise of our approach to develop a biocompatible nanomedicine platform for tumor-targeted delivery of Pc 4 for site-selective PDT.

  17. FADD null mouse embryonic fibroblasts undergo apoptosis after photosensitization with the silicon phthalocyanine Pc 4.

    Science.gov (United States)

    Nagy, B; Yeh, W C; Mak, T W; Chiu, S M; Separovic, D

    2001-01-01

    Oxidative stress, such as photodynamic therapy with the silicon phthalocyanine Pc 4 (Pc 4-PDT), can induce apoptosis and tumor necrosis factor alpha (TNF) production. TNF receptors, as well as other death receptors, have been implicated in stress-induced apoptosis. To assess directly the role of FADD, a death receptor-associated protein, in induction of apoptosis post-Pc 4-PDT, embryonic fibroblasts from FADD knock out (k/o) and wild-type (wt) mice were used. Pc 4-PDT induced casp-3 activation and apoptosis in both cell types. In the presence of zVAD, a pancaspase inhibitor, Pc 4-PDT-induced apoptosis was abrogated in both cell lines. Fumonisin B1 (FB), an inhibitor of ceramide synthase, had no effect on apoptosis after Pc 4-PDT in either cell line. Similar to Pc 4-PDT, exogenous C6-ceramide bypassed FADD deficiency and induced zVAD-sensitive apoptosis. In contrast to Pc 4 photosensitization, TNF did not induce either apoptosis or ceramide accumulation in FADD k/o cells. In the absence of FADD deficiency, TNF-induced apoptosis was zVAD-sensitive and FB-insensitive. Induced ceramide levels remained elevated after cotreatment with TNF and zVAD in FADD wt cells. Taken together, these data provide genetic evidence for a lack of FADD requirement in Pc 4-PDT- or C6-ceramide-induced apoptosis. FB-sensitive ceramide production accompanies, but does not suffice, for apoptosis after Pc 4 photosensitization or TNF.

  18. Modifying excitation light dose of novel photosensitizer PVP-Hypericin for photodynamic diagnosis and therapy.

    Science.gov (United States)

    Penjweini, Rozhin; Loew, Hans G; Eisenbauer, Maria; Kratky, Karl W

    2013-03-05

    Conventional photodynamic diagnosis (PDD) and therapy (PDT) makes use of photosensitizers that are excited by continuous light irradiation of specific wavelengths. In the case of PDT, the overdose of continuous excitation may lead to an expansion of necrosis in cancer cells or morbidity in healthy surroundings. The present study involves 5-h fluorescence imaging of living human lung epithelial carcinoma cells (A549) in the presence of a novel photosensitizer, PVP-Hypericin (PVP: polyvinylpyrrolidone) to optimize the excitation light doses for PDD and PDT. A number of time-lapse imaging experiments were performed using a low-power blue LED operating in either continuous or pulsed mode. The irradiances I(*) were 1.59, 6.34 and 14.27mW/cm(2), the pulse lengths L being 0.127, 1.29, 13, 54.5, 131 and 60,000ms. Then, the relation between irradiance, various exposure times, photobleaching and phototoxicity of PVP-Hyperycin was investigated. Results showed a nonlinear relationship between the amounts of excitation dose, cell viability and toxicity. For all experimental I(*), minimal phototoxicity and photobleaching was detected when cells were exposed to brief pulses of light (L⩽13ms). On the other hand, pulsed excitation with I(*)=14.27mW/cm(2) and L=131ms induced high percentages of apoptosis comparable to the long exposures of L=60,000ms and the continuous excitation. Thus, replacement of continuous excitation by a pulsed method seems applicable for PDT.

  19. Investigating Photosensitized Properties of Natural Organic Matter and Effluent Organic Matter

    KAUST Repository

    Niu, Xi-Zhi

    2013-05-01

    The photosensitized processes significantly enhance photolysis of various chemicals in the aqueous system with dissolved organic matter (DOM) as sensitizer. The excitation of chromophores on the DOM molecule further generates reactive species as triplet states DOM, singlet oxygen, hydroxyl radical, carbonate radical etc. We investigated the photosensitization properties of Beaufort Fulvic Acid, Suwannee River Fulvic Acid, South Platte River Fulvic Acid, and Jeddah wastewater treatment plant effluent organic matter with a sunlight simulator. DOM photochemical properties were characterized by observing their performances in 3DOM*, singlet oxygen, hydroxyl radical production with indirect probing protocols. Sensitized degradation of 0.1 μM and 0.02 μM 2, 4, 6- Trimethylphenol exhibited higher pseudo-first-order rate constant than that of 10 μM. Pre-irradiated DOMs were found to be depressed in photochemical properties. Photolysis of 5 different contaminants: ibuprofen, bisphenol A, acetaminophen, cimetidine, and caffeine were found to be enhanced in the presence of sensitizers. The possible reaction pathways were revealed. Long time irradiance induced change in contaminants degradation kinetics in some DOM solutions, which was proposed to be due to the irradiation initiated indirect transformation of DOMs. Key Words: Photolysis Dissolved Organic Matter, Triplet State DOM, Singlet Oxygen, Hydroxyl Radical, Contaminants Degradation.

  20. Water-Insoluble Photosensitizer Nanocolloids Stabilized by Supramolecular Interfacial Assembly towards Photodynamic Therapy

    Science.gov (United States)

    Liu, Yamei; Ma, Kai; Jiao, Tifeng; Xing, Ruirui; Shen, Guizhi; Yan, Xuehai

    2017-02-01

    Nanoengineering of hydrophobic photosensitizers (PSs) is a promising approach for improved tumor delivery and enhanced photodynamic therapy (PDT) efficiency. A variety of delivery carriers have been developed for tumor delivery of PSs through the enhanced permeation and retention (EPR) effect. However, a high-performance PS delivery system with minimum use of carrier materials with excellent biocompatibility is highly appreciated. In this work, we utilized the spatiotemporal interfacial adhesion and assembly of supramolecular coordination to achieve the nanoengineering of water-insoluble photosensitizer Chlorin e6 (Ce6). The hydrophobic Ce6 nanoparticles are well stabilized in a aqueous medium by the interfacially-assembled film due to the coordination polymerization of tannic acid (TA) and ferric iron (Fe(III)). The resulting Ce6@TA-Fe(III) complex nanoparticles (referenced as Ce6@TA-Fe(III) NPs) significantly improves the drug loading content (~65%) and have an average size of 60 nm. The Ce6@TA-Fe(III) NPs are almost non-emissive as the aggregated states, but they can light up after intracellular internalization, which thus realizes low dark toxicity and excellent phototoxicity under laser irradiation. The Ce6@TA-Fe(III) NPs prolong blood circulation, promote tumor-selective accumulation of PSs, and enhanced antitumor efficacy in comparison to the free-carrier Ce6 in vivo evaluation.

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

    Directory of Open Access Journals (Sweden)

    Gisela M F Vaz

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

  2. Phase diagrams of DNA-photosensitive surfactant complexes: effect of ionic strength and surfactant structure.

    Science.gov (United States)

    Zakrevskyy, Yuriy; Titov, Evgenii; Lomadze, Nino; Santer, Svetlana

    2014-10-28

    Realization of all-optically controlled and efficient DNA compaction is the major motivation in the study of interactions between DNA and photosensitive surfactants. In this article, using recently published approach of phase diagram construction [Y. Zakrevskyy, P. Cywinski, M. Cywinska, J. Paasche, N. Lomadze, O. Reich, H.-G. Löhmannsroben, and S. Santer, J. Chem. Phys. 140, 044907 (2014)], a strategy for substantial reduction of compaction agent concentration and simultaneous maintaining the light-induced decompaction efficiency is proposed. The role of ionic strength (NaCl concentration), as a very important environmental parameter, and surfactant structure (spacer length) on the changes of positions of phase transitions is investigated. Increase of ionic strength leads to increase of the surfactant concentration needed to compact DNA molecule. However, elongation of the spacer results to substantial reduction of this concentration. DNA compaction by surfactants with longer tails starts to take place in diluted solutions at charge ratios Z phase diagrams for different DNA-photosensitive surfactant systems allowed explanation and proposal of a strategy to overcome previously reported limitations of the light-induced decompaction for complexes with increasing surfactant hydrophobicity.

  3. Area-selective atomic layer deposition of platinum using photosensitive polyimide

    Science.gov (United States)

    Vervuurt, René H. J.; Sharma, Akhil; Jiao, Yuqing; Kessels, Wilhelmus (Erwin M. M.; Bol, Ageeth A.

    2016-10-01

    Area-selective atomic layer deposition (AS-ALD) of platinum (Pt) was studied using photosensitive polyimide as a masking layer. The polyimide films were prepared by spin-coating and patterned using photolithography. AS-ALD of Pt using poly(methyl-methacrylate) (PMMA) masking layers was used as a reference. The results show that polyimide has excellent selectivity towards the Pt deposition, after 1000 ALD cycles less than a monolayer of Pt is deposited on the polyimide surface. The polyimide film could easily be removed after ALD using a hydrogen plasma, due to a combination of weakening of the polyimide resist during Pt ALD and the catalytic activity of Pt traces on the polyimide surface. Compared to PMMA for AS-ALD of Pt, polyimide has better temperature stability. This resulted in an improved uniformity of the Pt deposits and superior definition of the Pt patterns. In addition, due to the absence of reflow contamination using polyimide the nucleation phase during Pt ALD is drastically shortened. Pt patterns down to 3.5 μm were created with polyimide, a factor of ten smaller than what is possible using PMMA, at the typical Pt ALD processing temperature of 300 °C. Initial experiments indicate that after further optimization of the polyimide process Pt features down to 100 nm should be possible, which makes AS-ALD of Pt using photosensitive polyimide a promising candidate for patterning at the nanoscale.

  4. Effective inactivation of food pathogens Listeria monocytogenes and Salmonella enterica by combined treatment of hypericin-based photosensitization and high power pulsed light.

    Science.gov (United States)

    Kairyte, K; Lapinskas, S; Gudelis, V; Luksiene, Z

    2012-06-01

    The aim of this study was to evaluate the inactivation efficiency of Listeria monocytogenes ATC(L3) C 7644 and Salmonella enterica serovar Typhimurium strain DS88 by combined treatment of hypericin (Hyp)-based photosensitization and high power pulsed light (HPPL). Cells were incubated with Hyp (1 × 10(-5) or 1 × 10(-7) mol l(-1)) in PBS and illuminated with a light λ = 585 nm. For the combined treatment, bacteria were, after photosensitization, exposed to 350 pulses of HPPL (UV light dose = 0·023 J cm(-2)). Fluorescence measurements were performed to evaluate optimal time for cell-Hyp interaction. Results indicate that Hyp tends to bind both Listeria and Salmonella. After photosensitization treatment, Listeria population was reduced 7 log, whereas Salmonella was inactivated just 1 log. Electron photomicrograps of Salmonella and Listeria confirmed that photosensitization induced total collapse of the Listeria cell wall, but not that of Salmonella. After combined photosensitization-HPPL treatment, the population of Listeria was diminished by 7 log and Salmonella by 6·7 log. Listeria can be effectively inactivated by Hyp-based photosensitization (7 log), whereas Salmonella is more resistant to photosensitization and can be inactivated just by 1 log in vitro. Combined treatment of photosensitization and pulsed light inactivates effectively (6·7-7 log) both the Gram-positive and the more resistant to photosensitization Gram-negative bacteria. A new approach to combat Gram-positive and Gram-negative bacteria is proposed, combining photosensitization with high power pulsed light. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

  5. Switchable PDT for reducing skin photosensitization by a NIR dye inducing self-assembled and photo-disassembled nanoparticles.

    Science.gov (United States)

    Zhang, Yifan; He, Lingyi; Wu, Jie; Wang, Kaikai; Wang, Juan; Dai, Weimin; Yuan, Ahu; Wu, Jinhui; Hu, Yiqiao

    2016-11-01

    Photodynamic therapy (PDT) is the combination of light and photosensitizer (PS) to kill tumor cells, which has the potential to meet many currently unmet medical needs. However, the whole body distribution and activatability by sunlight of photosensitizers to induce skin photosensitivity have limited the extensive clinic application of PDT. Herein, a novel strategy is presented to overcome these limitations by using a hydrophobic Near-infared (NIR) dye IR-780 iodide (IR780) to induce the self-assembly of albumin-PS conjugates, as a switchable PDT (Switch-PDT) agent. The PDT effect of PS is effectively inhibited by IR780 and recovered by NIR light irradiation in vitro. This quench/recovery strategy dose not sacrifice the anti-tumor ability in vivo, and the combined PDT and PTT (photothermal) effect contributes a very effective tumor inhibition rate of 100%. More importantly, the PDT effect is significantly suppressed after intravenous administration in mice or subcutaneous administration in rabbits as exhibited by the negligible skin response, while traditional PDT agent arouses severe skin erythema and edema. To the best of our knowledge, the switchable PDT is the first time to be used to eradicate the skin photosensitization of PS in vivo.

  6. Photosensitivity mechanism of undoped poly(methyl methacrylate) under UV radiation at 325 nm and its spatial resolution limit

    DEFF Research Database (Denmark)

    Sáez-Rodríguez, D.; Nielsen, Kristian; Bang, Ole;

    2014-01-01

    In this Letter, we provide evidence suggesting that the main photosensitive mechanism of an undoped poly(methyl methacrylate)-based microstructured optical fiber under UV radiation at 325 nm is a competitive process of both photodegradation and polymerization. We found experimentally that increas...

  7. Photosensitizing agents and the risk of non-melanoma skin cancer: a population-based case-control study.

    Science.gov (United States)

    Robinson, Sarah N; Zens, Michael S; Perry, Ann E; Spencer, Steven K; Duell, Eric J; Karagas, Margaret R

    2013-08-01

    It is well-known that UV light exposure and a sun-sensitive phenotype are risk factors for the development of non-melanoma skin cancer (NMSC), including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). In this New Hampshire population-based case-control study, we collected data from 5,072 individuals, including histologically confirmed cases of BCC and SCC, and controls via a personal interview to investigate possible associations between photosensitizing medication use and NMSC. After adjustment for potentially confounding factors (e.g., lifetime number of painful sunburns), we found a modest increase in risk of SCC (odds ratio (OR)=1.2, 95% confidence interval (CI)=1.0-1.4) and BCC (OR=1.2, 95% CI=0.9-1.5), in particular early-onset BCC, (≤ 50 years of age) (OR=1.5, 95% CI=1.1-2.1) associated with photosensitizing medication use. For SCC the association was strongest among those with tendency to sunburn rather than tan. We also specifically found associations with BCC, and especially early-onset BCC, and photosensitizing antimicrobials. In conclusion, certain commonly prescribed photosensitizing medications may enhance the risk of developing SCC, especially in individuals with a sun-sensitive phenotype, and may increase the risk of developing BCC and incidence of BCC at a younger age.

  8. Release of inflammatory mediators (PGE2, IL-6) by fenofibric acid-photosensitized human keratinocytes and fibroblasts.

    Science.gov (United States)

    Terencio, M C; Guillén, I; Gómez-Lechón, M J; Miranda, M A; Castell, J V

    1998-09-01

    Ultraviolet-A radiation has weak effects on the release of inflammatory mediators by skin cells due to the poor overlap between UVA wavelengths and the absorption spectra of the relevant chromophores of key biomolecules. However, this situation could be very different in the presence of a photosensitizing drug. To investigate this issue, we have irradiated human skin cells (keratinocytes and fibroblasts) in the presence of fenofibric acid (the active phototoxic metabolite of fenofibrate). The results of this research show a dual effect on the production/release of inflammatory mediators: the synthesis of the proinflammatory cytokine interleukin-6 becomes strongly inhibited at photosensitizer concentrations that clearly stimulate the production of prostaglandins (PGE2) by skin cells. We have found evidences showing that the de novo synthesis of cytokines is inhibited in photosensitized cells due to the fact that cellular mRNA is degraded. Interestingly, when the medium taken from irradiated cultures is added to nonexposed cells, a significant stimulation of cytokine synthesis is observed that can be inhibited by anti-PGE2 antibodies. These observations may be relevant in vivo, where prostaglandins released by photosensitized skin cells could stimulate cytokine synthesis by underlying, nonirradiated cells.

  9. Photosensitive gas detectors for the ring-imaging Cherenkov (RICH) technique and the DELPHI barrel RICH prototype

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, R.; Berst, J.D.; Christophel, E.; Guyonnet, J.L.; Baillon, P.; Bosteels, M.; Passardi, G.; Besch, H.J.; Seguinot, J.; Tocqueville, J.

    1986-12-01

    After a short introduction to the ring-imaging technique, the principal types of photosensitive gas detectors are discussed. In the second part, status and results of the DELPHI barrel RICH prototype are presented. A short description of a possible very fast RICH for future hadron colliders is given.

  10. Novel type 1 photosensitizers: viability of leukemia cells exposed to reactive intermediates generated in situ by in vitro photofragmentation

    Science.gov (United States)

    Rajagopalan, Raghavan; Karwa, Amol; Lusiak, Przemyslaw M.; Srivastava, Kripa; Poreddy, Amruta R.; Pandurangi, Raghootama S.; Galen, Karen P.; Neumann, William L.; Cantrell, Gary E.; Dorshow, Richard B.

    2009-06-01

    Photodynamic therapy of tumors involving Type 2 photosenstizers has been conspicuously successful, but the Type 1 process, in contrast, has not received much attention despite its considerable potential. Accordingly, several classes of molecules containing fragile bonds such as azido (-N=N=N), azo (-N=N-), sulfenato (-S-O-) and oxaza (-N-O-) functional groups that produce reactive intermediates such as radicals and nitrenes upon photoexcitation were prepared and tested for cell viability using U397 leukemia cell line. The azido photosensitizer was conjugated to leukemia cell binding peptide, SFFWRLS, for targeted cell viability study. The cells were incubated with the photosensitizer at various concentrations, and were illuminated for 5, 10, and 20 minutes. The results show that all the photosensitizers caused cell death compared to the controls when exposed to both the photosensitizers and light. Most importantly, selective cell death was observed with the azido peptide conjugate 6, which clearly demonstrates that these Type 1 sensitizers are useful for phototherapeutic applications.

  11. Photosensitive structures based on CuIn{sub 5}Te{sub 8} single crystals: Development and properties

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, I. V. [Belarussian State University of Information Science and Radioelectronics (Belarus); Rud, V. Yu. [St. Petersburg State Polytechnical University (Russian Federation); Rud, Yu. V., E-mail: Yuryrud@mail.ioffe.ru; Terukov, E. I. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Kovalchuk, A. M. [Belarussian State University of Information Science and Radioelectronics (Belarus)

    2011-05-15

    A new ternary compound is synthesized for the first time, and bulk CuIn{sub 5}Te{sub 8} single crystals are grown by directed crystallization of near-stoichiometric melt. It is established from X-ray diffraction patterns of grown crystals that they exhibit the structure of imperfect chalcopyrite with parameters of the unit cell of CuIn{sub 5}Te{sub 8}, which were close to those known for the CuInTe{sub 2} ternary compound with the composition index n = 0. First, photosensitive structures are fabricated based on CuIn{sub 5}Te{sub 8} crystals, and photosensitivity spectra are obtained for them; it is shown that it is possible to achieve broadband photosensitivity under illumination of the barrier side of these crystals. From the analysis of photosensitivity spectra, the character of band-to-band transitions and corresponding energies of these transitions in CuIn{sub 5}Te{sub 8} are determined. This opens up prospects to use this new semiconductor in photoconverters of solar radiation.

  12. Photo-induced oxidative damage to dissolved free amino acids by the photosensitizer polycyclic musk tonalide: Transformation kinetics and mechanisms.

    Science.gov (United States)

    Fang, Hansun; Gao, Yanpeng; Wang, Honghong; Yin, Hongliang; Li, Guiying; An, Taicheng

    2017-05-15

    Residue from the polycyclic musks (PCMs) in household and personal care products may harm human beings through skin exposure. To understand the health effects of PCMs when exposed to sunlight at molecular level, both experimental and computational methods were employed to investigate the photosensitized oxidation performance of 19 natural amino acids, the most basic unit of life. Results showed that a typical PCM, tonalide, acts as a photosensitizer to significantly increase photo-induced oxidative damage to amino acids. Both common and exceptional transformation pathways occurred during the photosensitization damage of amino acids. Experimental tests further identified the different mechanisms involved. The common transformation pathway occurred through the electron transfer from α amino-group of amino acids, accompanying with the formation of O2(•-). This pathway was controlled by the electronic density of N atom in α amino-group. The exceptional transformation pathway was identified only for five amino acids, mainly due to the reactions with reactive oxygen species, e.g. (1)O2 and excited triplet state molecules. Additionally, tonalide photo-induced transformation products could further accelerate the photosensitization of all amino acids with the common pathway. This study may support the protection of human health, and suggests the possible need to further restrict polycyclic musks use.

  13. Studies of a novel photosensitizer Pd-bacteriopheophorbide (Tookad) for the prostate cancer PDT in canine model

    Science.gov (United States)

    Huang, Zheng; Chen, Qun; Brun, Pierre-Herve; Wilson, Brian C.; Scherz, Avigdor; Salomon, Yoram; Luck, David L.; Beckers, Jill; Hetzel, Fred W.

    2003-12-01

    Photodynamic therapy (PDT) mediated with vascular acting photosensitizer pd-bacteriopheophorbide (Tookad), is investigated as an alternative modality for the total ablation of prostate cancer. In vivo normal canine prostate is used as the animal model. Interstitial PDT was performed by irradiating the surgically exposed prostates with a diode laser (763 nm, 150 mW/cm) to activate the i.v. infused photosensitizer drug. The effects of two-session PDT were evaluated. The prostate and its adjacent tissues were harvested and subjected to histopathological examination. At one-week, post second-session PDT, the animals recovered well with little or no urethral complications. Prostatic urethra and prostate adjacent tissues (bladder and underlying colon) were well preserved. Two-session PDT or one single session PDT induced a similar extent of damage. PDT induced prostate lesions were characterized by marked hemorrhagic necrosis. Maximum lesion size of over 3 cm in dimension could be achieved with a single 1-cm interstitial treatment, suggesting the therapy is very effective in ablating prostatic tissue. Pharmacokinetic studies show that the photosensitizer is cleared rapidly from the circulation. In conclusion, the novel photosensitizer Tookad mediated PDT may provide an effective alternative to treat prostate cancer.

  14. Tumor mitochondria-targeted photodynamic therapy with a translocator protein (TSPO)-specific photosensitizer.

    Science.gov (United States)

    Zhang, Shaojuan; Yang, Ling; Ling, Xiaoxi; Shao, Pin; Wang, Xiaolei; Edwards, W Barry; Bai, Mingfeng

    2015-12-01

    Photodynamic therapy (PDT) has been proven to be a minimally invasive and effective therapeutic strategy for cancer treatment. It can be used alone or as a complement to conventional cancer treatments, such as surgical debulking and chemotherapy. The mitochondrion is an attractive target for developing novel PDT agents, as it produces energy for cells and regulates apoptosis. Current strategy of mitochondria targeting is mainly focused on utilizing cationic photosensitizers that bind to the negatively charged mitochondria membrane. However, such an approach is lack of selectivity of tumor cells. To minimize the damage on healthy tissues and improve therapeutic efficacy, an alternative targeting strategy with high tumor specificity is in critical need. Herein, we report a tumor mitochondria-specific PDT agent, IR700DX-6T, which targets the 18kDa mitochondrial translocator protein (TSPO). IR700DX-6T induced apoptotic cell death in TSPO-positive breast cancer cells (MDA-MB-231) but not TSPO-negative breast cancer cells (MCF-7). In vivo PDT study suggested that IR700DX-6T-mediated PDT significantly inhibited the growth of MDA-MB-231 tumors in a target-specific manner. These combined data suggest that this new TSPO-targeted photosensitizer has great potential in cancer treatment. Photodynamic therapy (PDT) is an effective and minimally invasive therapeutic technique for treating cancers. Mitochondrion is an attractive target for developing novel PDT agents, as it produces energy to cells and regulates apoptosis. Current mitochondria targeted photosensitizers (PSs) are based on cationic molecules, which interact with the negatively charged mitochondria membrane. However, such PSs are not specific for cancerous cells, which may result in unwanted side effects. In this study, we developed a tumor mitochondria-targeted PS, IR700DX-6T, which binds to translocator protein (TSPO). This agent effectively induced apoptosis in TSPO-positive cancer cells and significantly

  15. Effects of photosensitizer (hematoporphyrin derivative-HPD) and light dose on vascular targets in the albino mouse ear

    Energy Technology Data Exchange (ETDEWEB)

    Davis, R.K.; Davis, K.; Straight, R.C.; Waner, M.

    1988-01-01

    Photodynamic damage to normal tissues, including skin, appears to occur by photooxidative damage to the normal microvasculature as the primary target sensitized by HPD bound to the vascular wall or endothelial cell. Initial damage to the microvasculature was measured by the increase in vascular permeability (VP) as measured by Evans Blue dye (EB) extravasation as a function of HPD and laser light (632 nm) dose. Albino, Swiss-Webster mice (female 122-25 g, 5 mice per group) were injected intraperitoneally (IP) with incremental doses of HPD (1, 10, 20, 30, 40 and 50 mg/kg). After 48 hours the left ear of each mouse was masked as a control and the right ear was irradiated at 632 nm using the Aurora-Lexel Argon-dye laser with an intensity of 50 mW/cm2 and light doses of 0, 25, 50, 75, and 100 J/cm2 directed to a 3-mm spot on the mouse ear. No EB leakage occurred in the absence of HPD at any light dose or in the absence of light at any HPC dose. Vascular permeability increased as a function of HPD dose up to 30 mg/kg. AT 50 mg/kg HPD, there was a decrease in VP. At each HPD dose above 10 mg/kg, the VP increased as a function of light dose up to 75 J/cm2. Further increase in light dose was without effect. The amount of HPD porphyrin recovered from irradiated ears decreased as a function of light dose. There appeared to be an irreversible photo destruction of the porphyrin exposed to light.

  16. ZnO UV photodetector with controllable quality factor and photosensitivity

    Directory of Open Access Journals (Sweden)

    L. C. Campos

    2013-02-01

    Full Text Available ZnO nanowires have an enormous potential for applications as ultra-violet (UV photodetectors. Their mechanism of photocurrent generation is intimately related with the presence of surface states where considerable efforts, such as surface chemical modifications, have been pursued to improve their photodetection capabilities. In this work, we report a step further in this direction demonstrating that the relative photosensitivity and quality factor (Q factor of the photodetector are entirely tunable by an applied gate voltage. This mechanism enables UV photodetection selectivity ranging from wavelengths from tens of nanometers (full width at half maximum - FWHM down to a narrow detection of 3 nm. Such control paves the way for novel applications, especially related to the detection of elements that have very sharp luminescence.

  17. Synthesis of A Novel Photosensitive Prepolymer with Trimethylolpropane Triglycidylether and Acrylic Acid as Starting Materials

    Institute of Scientific and Technical Information of China (English)

    HUANG Biwu; HUANG Shuhuai; SHI Yusheng; MO Jianhua

    2005-01-01

    A novel photosensitive prepolymer of trimethylolpropane triglycidylether triacrylate was synthesized by utilizing trimethylolpropane triglycidylether and acrylic acid as two starting materials, triphenyl phosphine as catalyst and p-hydroxyanisole as inhibitor. The optimum synthesis conditions were that the concentration of triphenyl phosphine was 0.85wt% of reactants, the concentration of p-hydroxyanisole was 0.3wt% of reactants, and the reaction temperature was at 90-110 ℃. Benzil dimethyl ketal of a UV-cured initiator was added to the synthesized trimethylolpropane triglycidylether triacrylate to prepare a kind of UV-cured coating. The mechanical properties of the UV-cured films were determined, giving 28.43 MPa of tensile strength, 965.59MPa of Young's modulus and 4.10% of elongation at tear.

  18. Effect of Molecular Weight on Liquid Crystal Photoalignment by Photosensitive Polyester Containing Thrifluoromethyl Moieties

    Institute of Scientific and Technical Information of China (English)

    FEI Chun-Hong; PENG Zeng-Hui; LV Feng-Zhen; ZHANG Ling-Li; YAO Li-Shuang; XUAN Li

    2006-01-01

    @@ We investigate the liquid-crystal (LC) alignment direction on photoalignment films formed from photosensitive polyester containing thrifluoromethyl moieties (PPDA ) with various molecular weights by crossed polarized optical microscopy. It is found that LC alignment behaviour changes with molecular weight of PPDA. The LC alignment on PPDA irradiated films with the highest molecular weight is homogeneous, while those with low and intermediate molecular weights are homeotropic. However, surface morphologies show weak dependence on molecular weight. The surfaces are smooth and there is no clear morphological anisotropy on these aligned films observed by an atomic force microscope. The surface energies of the irradiated films are also measured by using an indirect contact-angle method where both surface energy and its polar componentincrease with increasing molecular weight. Different polar surface energies can be considered as a main reason for different alignment characteristics.

  19. Elliptical concave microlens arrays built in the photosensitive TiO2/ormosils hybrid films

    Science.gov (United States)

    Zhang, Xuehua; Que, Wenxiu; Javed, Hafiz M. Asif; Wei, Wei

    2014-11-01

    Photosensitive TiO2/organically modified silane hybrid thin films were prepared by a low-temperature sol-gel spin-coating technique. Optical and structural properties of the hybrid films with different titanium contents were characterized by prism coupling technique, UV-visible spectroscopy, Fourier transform infrared spectroscopy, and thermal gravimetric analysis. Advantages for fabrication of elliptical concave micro-lens arrays (MLAs) based on the as-prepared hybrid films were demonstrated by combining polydimethylsiloxane soft mold with a UV-cured imprint technique. Results indicate that the as-prepared hybrid films have great applicability for the fabrication of photonic components, and the fabrication technique provides a simple and cost-effective way for the fabrication of the sol-gel elliptical concave MLAs.

  20. Phototherapies: photosensitized inactivation of viral and protozoan infectious agents and potential application in blood banking

    Science.gov (United States)

    Judy, Millard M.; Matthews, James Lester; Sogandares-Bernal, Franklin M.; Newman, Joseph T.; Chanh, Tran C.; Marengo-Rowe, Alain J.

    1992-06-01

    More than 10 million units of human blood components are processed annually in the United States. Although donor screening and testing have greatly lowered the risk of transmission of viral and protozoan infectious agents, additional sterilization procedures which also preserve blood component function would be of significant value. Use of UV-A and visible-light-range photosensitizers for sterilization of blood platelets and red blood cells, respectively, is currently being aggressively investigated in laboratory-scale optical-mechanical systems. With successful demonstration of the efficacy and safety of these sterilization techniques, implementation in the blood bank setting will require scale-up to optical-mechanical systems capable of handling approximately 25,000 units daily in 500 - 1,000 blood banks in the United States.

  1. Photosensitized Oxidation of 9,10-Dimethylanthracene on Dye-Doped Silica Composites

    Directory of Open Access Journals (Sweden)

    Elim Albiter

    2012-01-01

    Full Text Available A series of cationic dyes, methylene blue (MB, safranin O (SF, toluidine blue (TB, and neutral red (NR, were successfully incorporated into a silica matrix by using ultrasound irradiation during the Stöber process. Several analyses were performed, including scanning dynamic light scattering (DLS, electron microscopy (SEM, nitrogen physisorption, FTIR spectroscopy, UV-vis, and diffuse reflectance spectroscopy. The entrapped dyes on silica were evaluated in singlet oxygen (1O2 generation under visible light irradiation, by means of the photosensitized oxidation of 9,10-dimethylanthracene (DMA. According to the results, the photocatalytic performance of the silica composites was improved, and the leakage of the dye from the particles was suppressed. Among these four different types of dye-doped silica composites, the SiO2-SF composite showed the most efficient delivery of 1O2.

  2. Analysis of Biomedical Signals by Flicker-Noise Spectroscopy: Identification of Photosensitive Epilepsy using Magnetoencephalograms

    CERN Document Server

    Timashev, S F; Yulmetyev, R M; Demin, S A; Panischev, O Yu; Shimojo, S; Bhattacharya, J

    2008-01-01

    The flicker-noise spectroscopy (FNS) approach is used to determine the dynamic characteristics of neuromagnetic responses by analyzing the magnetoencephalographic (MEG) signals recorded as the response of a group of control human subjects and a patient with photosensitive epilepsy (PSE) to equiluminant flickering stimuli of different color combinations. Parameters characterizing the analyzed stochastic biomedical signals for different frequency bands are identified. It is shown that the classification of the parameters of analyzed MEG responses with respect to different frequency bands makes it possible to separate the contribution of the chaotic component from the overall complex dynamics of the signals. It is demonstrated that the chaotic component can be adequately described by the anomalous diffusion approximation in the case of control subjects. On the other hand, the chaotic component for the patient is characterized by a large number of high-frequency resonances. This implies that healthy organisms can...

  3. Photocatalytic and Photoelectrochemical Water Splitting on TiO2 via Photosensitization

    Directory of Open Access Journals (Sweden)

    Saji Thomas Kochuveedu

    2016-01-01

    Full Text Available The search for an alternative to replace conventional fuel has been going on for years due to the limited storage of fossil fuel and excess CO2 emission from the fuel. Using H2 as fuel has gained wide attention recently, as well as consequently splitting of water into hydrogen and oxygen. Seminal semiconductors such as TiO2 and ZnO have their position of CB and VB in alignment with water reduction and oxidation potential, respectively, but their wide bandgap allows them to absorb only UV light of the solar spectrum. Combining narrow bandgap semiconductors or other visible light active sensitizers with TiO2/ZnO is a facile route to exploit the visible light region of the solar spectrum. In this review, I make an attempt to summarize the various photosensitizers used in combination with TiO2 for water splitting with recent reports as examples.

  4. Novel fully-BODIPY functionalized cyclotetraphosphazene photosensitizers having high singlet oxygen quantum yields

    Science.gov (United States)

    Şenkuytu, Elif; Eçik, Esra Tanrıverdi

    2017-07-01

    Novel fully-BODIPY functionalized dendrimeric cyclotetraphosphazenes (FBCP 1 and 2) have been synthesized and characterized by 1H, 13C and 31P NMR spectroscopies. The photophysical and photochemical properties of FBCP 1 and 2 are investigated in dichloromethane solution. The effectiveness of singlet oxygen generation was measured for FBCP 1 and 2 by UV-Vis spectra monitoring of the solution of 1,3-diphenylisobenzofuran (DPBF), which is a well-known trapping molecule used in detection of singlet oxygen. FBCP 1 and 2 show high molar extinction coefficients in the NIR region, good singlet oxygen quantum yields and appropriate photo degradation. The data presented in the work indicate that the dendrimeric cyclotetraphosphazenes are effective singlet oxygen photosensitizers that might be used for various areas of applications such as photodynamic therapy and photocatalysis.

  5. Stereocontrol of Methyl Methacrylate during Photoinduced Nitroxide-Mediated Polymerization in the Presence of Photosensitive Alkoxyamine

    Directory of Open Access Journals (Sweden)

    Juahui Su

    2016-01-01

    Full Text Available Photosensitive alkoxyamine 2,2,6,6-tetramethyl-1-(1-phenylethoxypiperidin-4-yl quinoline-2-carboxylate (PE-TEMPO-Q was synthesized. Photochemical properties of PE-TEMPO-Q were studied to develop photoinduced nitroxide-mediated polymerization of methyl methacrylate (MMA. Rapid and facile polymerization at ambient temperature with PE-TEMPO-Q as an initiator was confirmed to proceed in a controlled mechanism based on the linear growth in molecular weight combined with relative narrow polydispersity index (1.4–1.8 of the resulting polymers. The stereochemistry of obtained polymers was also investigated, and the syndiotacticity slightly increased compared with the typical photopolymerization. Dual-controlled photopolymerization of MMA was achieved in the presence of synthesized alkoxyamine.

  6. Protoporphyrin IX in the skin measured noninvasively predicts photosensitivity in patients with erythropoietic protoporphyria

    DEFF Research Database (Denmark)

    Heerfordt, I M; Wulf, H C

    2016-01-01

    BACKGROUND: Erythropoietic protoporphyria (EPP) is a rare genetic disease that causes severe sensitivity to visible light as a result of protoporphyrin IX (PpIX) accumulation in the skin. OBJECTIVES: To establish a noninvasive method to measure PpIX in the skin of patients with EPP...... and to investigate how skin PpIX relates to erythrocyte PpIX and photosensitivity. METHODS: Skin PpIX was measured in 25 patients with EPP by calculating the difference in PpIX fluorescence before and after complete photobleaching of PpIX using controlled illumination. The patients reported symptoms during...... the illumination and skin erythema was measured before and after illumination. Confirmation of the presence of PpIX was obtained in seven patients by measuring the in vivo fluorescence emission spectrum. This method was used to examine skin PpIX during the hours after an illumination in seven patients. RESULTS: We...

  7. Design and Fabrication of an Er-Doped Silica Optical Fiber with Six Photosensitive Subcores

    Institute of Scientific and Technical Information of China (English)

    LI Jian; WANG Jing; LIU Peng; LU Shao-Hua; MAO Xiang-Qiao; JIANG Wei-Wei; NING Ti-Gang; JIAN Shui-Sheng

    2009-01-01

    A type of multi-core Er-doped photosensitive silica optical fiber (MC-EDPF) is proposed and fabricated, in which a high consistency Er-doped core is surrounded by six high consistency Ge-doped cores. The multi-core design can overcome the difficulties encountered in the design and fabrication of single-core EDPFs through a modified chemical vapor deposition method combined with solution doping technology, and there is a conflict between high consistency Er doping and high consistency Ge doping. The absorption of MC-EDPFs achieved 15.876dB/m at 1550nm and 10dB/m at 980hm. The reflectivity of the fiber Bragg gratings (FBGs) written directly on the MC-EDPFs is as much as 96.84%.

  8. Phthalocyanine photosensitizers as contrast agents for in vivo photoacoustic tumor imaging.

    Science.gov (United States)

    Attia, Amalina Bte Ebrahim; Balasundaram, Ghayathri; Driessen, Wouter; Ntziachristos, Vasilis; Olivo, Malini

    2015-02-01

    There is a need for contrast agents for non-invasive diagnostic imaging of tumors. Herein, Multispectral Optoacoustic Tomography (MSOT) was employed to evaluate phthalocyanines commonly used in photodynamic therapy as photoacoustic contrast agents. We studied the photoacoustic activity of three water-soluble phthalocyanine photosensitizers: phthalocyanine tetrasulfonic acid (PcS4), Zn(II) phthalocyanine tetrasulfonic acid (ZnPcS4) and Al(III) phthalocyanine chloride tetrasulfonic acid (AlPcS4) in phantom and in tumor-bearing mice to investigate the biodistribution and fate of the phthalocyanines in the biological tissues. PcS4 was observed to grant good contrast between the different reticuloendothelial organs and accumulate in the tumor within an hour of post-administration. ZnPcS4 and AlPcS4 offered little contrast in photoacoustic signals between the organs. PcS4 is a promising photoacoustic contrast agent and can be exploited as a photodiagnostic agent.

  9. Transferrin receptor-targeted theranostic gold nanoparticles for photosensitizer delivery in brain tumors

    Science.gov (United States)

    Dixit, Suraj; Novak, Thomas; Miller, Kayla; Zhu, Yun; Kenney, Malcolm E.; Broome, Ann-Marie

    2015-01-01

    Therapeutic drug delivery across the blood-brain barrier (BBB) is not only inefficient, but also nonspecific to brain stroma. These are major limitations in the effective treatment of brain cancer. Transferrin peptide (Tfpep) targeted gold nanoparticles (Tfpep-Au NPs) loaded with the photodynamic pro-drug, Pc 4, have been designed and compared with untargeted Au NPs for delivery of the photosensitizer to brain cancer cell lines. In vitro studies of human glioma cancer lines (LN229 and U87) overexpressing the transferrin receptor (TfR) show a significant increase in cellular uptake for targeted conjugates as compared to untargeted particles. Pc 4 delivered from Tfpep-Au NPs clusters within vesicles after targeting with the Tfpep. Pc 4 continues to accumulate over a 4 hour period. Our work suggests that TfR-targeted Au NPs may have important therapeutic implications for delivering brain tumor therapies and/or providing a platform for noninvasive imaging.

  10. Fabrication and investigation of photosensitive MoOx/n-CdTe heterojunctions

    Science.gov (United States)

    Solovan, M. M.; Gavaleshko, N. M.; Brus, V. V.; Mostovyi, A. I.; Maryanchuk, P. D.; Tresso, E.

    2016-10-01

    MoOx/n-CdTe photosensitive heterostructures were prepared by the deposition of molybdenum oxide thin films onto n-type single-crystal CdTe substrates by DC reactive magnetron sputtering. The obtained heterojunctions possessed sharply defined rectifying properties with the rectification ration RR ˜ 106. The temperature dependences of the height of the potential barrier and series resistance of the MoOx/CdTe heterojunctions were investigated. The dominating current transport mechanisms through the heterojunctions were determined at forward and reverse biases. The analysis of capacitance-voltage (C-V) characteristics, measured at different frequencies of the small amplitude AC signal and corrected by the effect of the series resistance, provided evidence of the presence of electrically charged interface states, which significantly affect the measured capacitance.

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    to localize the sensitized production of singlet oxygen. Cells in close proximity to the domain of singlet oxygen production showed morphological changes commonly associated with necrotic cell death. The elapsed post-irradiation “waiting period” before necrosis became apparent depended on (a) the distance...... between the cell membrane and the domain irradiated, (b) the incident laser fluence and, as such, the initial concentration of singlet oxygen produced, and (c) the lifetime of singlet oxygen. The data imply that singlet oxygen plays a key role in this process of light-induced cell death. The approach...... of using extracellularly-generated singlet oxygen to induce cell death can provide a solution to a problem that often limits mechanistic studies of intracellularly photosensitized cell death: it can be difficult to quantify the effective light dose, and hence singlet oxygen concentration, when using...

  12. Characterization of transient species in laser photolysis of aromatic amino acids using acetone as photosensitizer

    Institute of Scientific and Technical Information of China (English)

    宋钦华; 徐业平; 俞书勤; 陈从香; 马兴孝; 王文锋; 姚思德; 林念芸

    1999-01-01

    The photochemical processes of aromatic amino acids were investigated in aqueous solution using acetone as photosensitizer by KrF (248 nm) laser flash photolysis. Laser-induced transient species were characterized according to kinetic analysis and quenching experiments. The intermediates recorded were assigned to the excited triplet state of tryptophan, the radicals of tryptophan and tyrosine. The excited triplet state of tryptophan produced via a triplet-triplet excitation transfer and the radicals arising from electron transfer reaction has been identified. Neither electron transfer nor energy transfer between triplet acetone and phenylalanine can occur in photolysis of phenylalanine aqueous solution which contains acetone. Furthermore, triplet acetone-induced radical transformation: Trp/N-Tyr→Trp-Tyr/O was observed directly in photolysis of dipeptide (Trp-Tyr) aqueous solution containing acetone, and the transformation resulting from intramolecular electron transfer was suggested.

  13. Inactivation of bacteria via photosensitization of vitamin K3 by UV-A light.

    Science.gov (United States)

    Xu, Fei; Vostal, Jaroslav G

    2014-09-01

    This study investigated inactivation of bacteria with ultraviolet light A irradiation in combination with vitamin K3 as a photosensitizer. Six bacteria including Bacillus cereus, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumoniae, and Escherichia coli suspended in vitamin K3 aqueous solution were exposed to ultraviolet light A. Five of six bacteria, with the exception of Pseudomonas aeruginosa, were reduced by eight logs with 1600 μM of vitamin K3 and 5.8 J cm(-2) UV-A irradiation. Pseudomonas aeruginosa was reduced by four logs under these conditions. Reactive oxygen species including singlet oxygen, hydroxyl radical and superoxide anion radical were generated in vitamin K3 aqueous solution under UV-A irradiation. These results suggest that vitamin K3 and UV-A irradiation may be effective for bacterial inactivation in environmental and medical applications. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  14. Conformational and phase transitions in DNA--photosensitive surfactant solutions: Experiment and modeling.

    Science.gov (United States)

    Kasyanenko, N; Lysyakova, L; Ramazanov, R; Nesterenko, A; Yaroshevich, I; Titov, E; Alexeev, G; Lezov, A; Unksov, I

    2015-02-01

    DNA binding to trans- and cis-isomers of azobenzene containing cationic surfactant in 5 mM NaCl solution was investigated by the methods of dynamic light scattering (DLS), low-gradient viscometry (LGV), atomic force microscopy (AFM), circular dichroism (CD), gel electrophoresis (GE), flow birefringence (FB), UV-Vis spectrophotometry. Light-responsive conformational transitions of DNA in complex with photosensitive surfactant, changes in DNA optical anisotropy and persistent length, phase transition of DNA into nanoparticles induced by high surfactant concentration, as well as transformation of surfactant conformation under its binding to macromolecule were studied. Computer simulations of micelles formation for cis- and trans-isomers of azobenzene containing surfactant, as well as DNA-surfactant interaction, were carried out. Phase diagram for DNA-surfactant solutions was designed. The possibility to reverse the DNA packaging induced by surfactant binding with the dilution and light irradiation was shown.

  15. In-vivo remission spectroscopy on tattoos and topically applied photosensitizers in man

    Science.gov (United States)

    Koenig, Karsten; Beck, Gerd C.; Boehncke, Wolf-Henning; Kaufmann, Roland; Hibst, Raimund

    1994-02-01

    In-vivo remission spectra of the human skin in the spectral region of 400 nm to 800 nm were recorded using a xenon lamp as an excitation source, a fiberoptical sensor combined with a polychromator, and a multichannel analyzer. The remission of amateur tattoos before and after laser treatment (Q-switched Nd:YAG) was measured and the degree of blanching determined. It was found that the process of blanching proceeds partly reversible. In another study, the time-dependent remission of human skin after topical administration of the photosensitizer Methylene Blue was studied. The additional application of the ceratolytic agent urea promotes the penetration of the thiazine dye. The experimental data were analyzed by the Kubelka Munk theory.

  16. Photosensitive spongiotic/lichenoid eruption of micropapules and plaques: A morphologically distinct entity

    Directory of Open Access Journals (Sweden)

    Nidhi Shah

    2013-01-01

    Full Text Available Background: A distinct morphological pattern of photodermatosis has been observed with shiny skin colored to hypopigmented tiny papules, discrete or coalescing to form plaques. Aims: To study the clinico-pathological features of patients presenting with these lesions. Methods: A total of 72 patients were recruited. Clinical examination and skin biopsy was carried out to evaluate the morphological patterns and the histopathological features. Results: In all patients, tiny discrete to coalescent papules were observed on sun-exposed sites but usually sparing the face. The condition occurred more commonly in women. Three specific histopathological patterns were observed : 0 spongiotic (43.7%, lichenoid (22.5%, psoriasiform (18.7% and also perivascular pattern in 5%. Conclusion: Photosensitive lichenoid eruption is a morphologically distinct photodermatoses that is commonly seen in Indian patients with pathological features showing mostly spongiotic changes and in some cases lichenoid changes.

  17. Photosensitizer-conjugated magnetic nanoparticles for in vivo simultaneous magnetofluorescent imaging and targeting therapy.

    Science.gov (United States)

    Huang, Peng; Li, Zhiming; Lin, Jing; Yang, Dapeng; Gao, Guo; Xu, Cheng; Bao, Le; Zhang, Chunlei; Wang, Kan; Song, Hua; Hu, Hengyao; Cui, Daxiang

    2011-05-01

    A major challenge in nanotechnology and nanomedicine is to integrate tumor targeting, imaging, and selective therapy functions into a small single nanoparticle (gastric cancer imaging and therapy. The second generation photosensitizer chlorin e6 (Ce6) was covalently anchored on the surface of magnetic nanoparticles with silane coupling agent. We found that the covalently incorporated Ce6 molecules retained their spectroscopic and functional properties for near-infrared (NIR) fluorescence imaging and photodynamic therapy (PDT), and the core magnetic nanoparticles offered the functions of magnetically guided drug delivery and magnetic resonance imaging (MRI). The as-prepared single particle platform is suitable for simultaneous targeting PDT and in vivo dual-mode NIR fluorescence imaging and MRI of nude mice loaded with gastric cancer or other tumors.

  18. Photosensitized rose Bengal-induced phototoxicity on human melanoma cell line under natural sunlight exposure.

    Science.gov (United States)

    Srivastav, Ajeet K; Mujtaba, Syed Faiz; Dwivedi, Ashish; Amar, Saroj K; Goyal, Shruti; Verma, Ankit; Kushwaha, Hari N; Chaturvedi, Rajnish K; Ray, Ratan Singh

    2016-03-01

    Rose Bengal (RB) is an anionic water-soluble xanthene dye, which used for many years to assess eye cornea and conjunctiva damage. RB showed strong absorption maxima (λmax) under visible light followed by UV-B and UV-A. RB under sunlight exposure showed a time-dependent photodegradation. Our results show that photosensitized RB generates (1)O2 via Type-II photodynamic pathway and induced DNA damage under sunlight/UV-R exposure. 2'dGuO degradation, micronuclei formation, and single- and double-strand breakage were the outcome of photogenotoxicity caused by RB. Quenching studies with NaN3 advocate the involvement of (1)O2 in RB photogenotoxicity. RB induced linoleic acid photoperoxidation, which was parallel to (1)O2-mediated DNA damage. Oxidative stress in A375 cell line (human melanoma cell line) was detected through DCF-DA assay. Photosensitized RB decreased maximum cellular viability under sunlight followed by UV-B and UV-A exposures. Apoptosis was detected as a pattern of cell death through the increased of caspase-3 activity, decreased mitochondrial membrane potential, and PS translocation through inner to outer plasma membrane. Increased cytosolic levels of Bax also advocate the apoptotic cell death. We propose a p53-mediated apoptosis via increased expression of Bax gene and protein. Thus, the exact mechanism behind RB phototoxicity was the involvement of (1)O2, which induced oxidative stress-mediated DNA and membrane damage, finally apoptotic cell death under natural sunlight exposure. The study suggests that after the use of RB, sunlight exposure may avoid to prevent from its harmful effects. Copyright © 2015. Published by Elsevier B.V.

  19. Free-standing coating patterns fabricated by ultraviolet contact lithography using photosensitive sol-gel coatings

    Science.gov (United States)

    Xiang, Youlai; Du, Ai; Li, Xiaoguang; Sun, Wei; Wu, Shuai; Li, Tiemin; Liu, Mingfang; Zhou, Bin

    2017-07-01

    Photosensitive ZrO2-SiO2 hybrid sol-gel coatings containing large contents of chelating rings were prepared by using the zirconium n-butoxide (TBOZ) and methyltriethoxysilane (MTES) as hybrid precursors, and benzoylacetone (BZAC) as chelating agent. The change of ultraviolet (UV) absorption spectra, chemical composition, and optical properties of ZrO2-SiO2 hybrid sol-gel coatings were analyzed before and after UV exposure and calcination. The refractive index of the ZrO2-SiO2 hybrid gel coatings decreased from 1.673 to 1.561 with the increase of the molar content of MTES in precursors. The sol-gel coating patterns with the periods of 20.24 μm, 10.11 μm and 3.99 μm on the PAMS substrates were firstly obtained by using the photosensitive ZrO2-SiO2 hybrid sol-gel films as fundamental materials through a process of UV contact lithography with photo masks and etching with ethanol. Finally, the free-standing gel coating patterns supported by copper grids, with the period of 12.70 μm and line width of 4.93 μm, and the period of 14.20 μm and line width of 3.82 μm, were obtained by removing the PAMS thermal degradation sacrifice layer after being calcined at 330 °C. Micrometer-periodic free-standing gel coating patterns with different structure have potential applications in the laser physical experiments.

  20. Development of Japonica Male Sterile Lines Integrating Cytoplasmic Male Sterility and Photosensitive Genic Male Sterility

    Institute of Scientific and Technical Information of China (English)

    WANG Shou-hai; DU Shi-yun; WANG De-zheng; LI Cheng-quan

    2005-01-01

    It has been previously established that the BT type of cytoplasmic male sterility (CMS) is induced by high temperatures,while photosensitive genic male sterility (PGMS) seed sets by low temperatures induce. In the current study, we have bred photosensitive cytoplasmic male sterility (PCMS) lines (2308SA and 2310SA) by crossing the CMS line with the PGMS japonica line with maintainer genes. The sterility of PCMS japonica was consequently controlled by two groups of male sterile genes resulting from the integration of PGMS and CMS genes. The results on plant fertility, at different sowing times, were as follows: (a) Under conditions of natural long-day photoperiod and at temperatures above 35℃, the PGMS gene regulated PCMS japonica sterility - the higher the temperature, the lower the pollen fertility. However, bagged seed sets of PCMS japonica, not exposed to high temperatures, induced the CMS seed set. (b) Exposure to long-day photoperiod and temperature conditions between 35℃ and the critical sterility inducing temperature of PGMS resulted in both PGMS and CMS gene controlled sterility of PCMS japonica, which exhibited stable characteristics. (c) When exposed to critical sterility inducing temperatures or short-day photoperiod and daily high temperatures below 32℃, the BT type of the CMS gene regulated PCMS sterility. Under these conditions, the PGMS gene rendered male sterility insusceptible to occasional cool summer days when this PCMS line, adopted for hybrid seed production, develops into panicle differentiation stage.The present study also investigated the fertility restoration, seed production and combining ability of PCMS japonica so as to optimize its use.

  1. Construction and Evaluation of a Targeted Hyaluronic Acid Nanoparticle/Photosensitizer Complex for Cancer Photodynamic Therapy.

    Science.gov (United States)

    Gao, Shi; Wang, Jingjing; Tian, Rui; Wang, Guohao; Zhang, Liwen; Li, Yesen; Li, Lu; Ma, Qingjie; Zhu, Lei

    2017-09-12

    Photodynamic therapy (PDT) is a novel treatment modality that is under intensive preclinical investigations for a variety of diseases, including cancer. Despite extensive studies in this area, selective and effective photodynamic agents that can specifically accumulate in tumors to reach a therapeutic concentration are limited. Although recent attempts have produced photosensitizers (PSs) complexed with various nanomaterials, the tedious preparation steps and poor tumor efficiency of therapy hamper their utilization. Here, we developed a CD44-targeted nanophotodynamic agent by physically encapsulating a photosensitizer, Ce6, into a hyaluronic acid nanoparticle (HANP), which was hereby denoted HANP/Ce6. Its physical features and capability for photodynamic therapy were characterized in vitro and in vivo. Systemic delivery of HANP/Ce6 resulted in its accumulation in a human colon cancer xenograft model. The tumor/muscle ratio reached 3.47 ± 0.46 at 4 h post injection, as confirmed by fluorescence imaging. Tumor growth after HANP/Ce6 treatment with laser irradiation (0.15 W/cm(2), 630 nm) was significantly inhibited by 9.61 ± 1.09-fold compared to that in tumor control groups, which showed no change in tumor growth. No apparent systemic and local toxic effects on the mice were observed. HANP/Ce6-mediated tumor growth inhibition was accessed and observed for the first time by (18)F-fluoro-2-deoxy-d-glucose positron emission tomography as early as 1 day after treatment and persisted for 14 days within our treatment time window. In sum, our results highlight the imaging properties and therapeutic effects of the novel HANP/Ce6 theranostic nanoparticle for CD44-targeted PDT cancer therapy that may be potentially utilized in the clinic. This HANP system may also be applied for the delivery of other hydrophobic PSs, particularly those that could not be chemically modified.

  2. Two-cationic 2-methylbenzothiazole derivatives as green light absorbed sensitizers in initiation of free radical polymerization

    OpenAIRE

    2015-01-01

    N-Methylpyridinium esters derivatives of 2-methylbenzothiazole hemicyanine dyes photoinitiators/photosensitizers derived from N-propyl-3-[N-2-methylbenzothiazolo]-4-pyridyno phenylacetic acid ester diiodide and N-propyl-3-[N-2-me]thylbenzothiazolo]-4-pyridino diphenylacetic acid ester diiodide were synthesized and proposed as new photoinitiators of polymerization of 2-ethyl-(2-hydroxymethyl)-1,3-propanediol triacrylate under argon laser exposure at 514 nm. These compounds exhibit a strong abs...

  3. Photodynamic treatment with phenothiazinium photosensitizers kills both ungerminated and germinated microconidia of the pathogenic fungi Fusarium oxysporum, Fusarium moniliforme and Fusarium solani.

    Science.gov (United States)

    de Menezes, Henrique Dantas; Tonani, Ludmilla; Bachmann, Luciano; Wainwright, Mark; Braga, Gilberto Úbida Leite; von Zeska Kress, Marcia Regina

    2016-11-01

    The search for alternatives to control microorganisms is necessary both in clinical and agricultural areas. Antimicrobial photodynamic treatment (APDT) is a promising light-based approach that can be used to control both human and plant pathogenic fungi. In the present study, we evaluated the effects of photodynamic treatment with red light and four phenothiazinium photosensitizers (PS): methylene blue (MB), toluidine blue O (TBO), new methylene blue N (NMBN) and the phenothiazinium derivative S137 on ungerminated and germinated microconidia of Fusarium oxysporum, F. moniliforme, and F. solani. APDT with each PS killed efficiently both the quiescent ungerminated microconidia and metabolically active germinated microconidia of the three Fusarium species. Washing away the unbound PS from the microconidia (both ungerminated and germinated) before red light exposure reduced but did not prevent the effect of APDT. Subcelullar localization of PS in ungerminated and germinated microconidia and the effects of photodynamic treatment on cell membranes were also evaluated in the three Fusarium species. APDT with MB, TBO, NMBN or S137 increased the membrane permeability in microconidia and APDT with NMBN or S137 increased the lipids peroxidation in microconidia of the three Fusarium species. These findings expand the understanding of photodynamic inactivation of filamentous fungi with phenothiazinium PS. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. The clinically used photosensitizer Verteporfin (VP) inhibits YAP-TEAD and human retinoblastoma cell growth in vitro without light activation.

    Science.gov (United States)

    Brodowska, Katarzyna; Al-Moujahed, Ahmad; Marmalidou, Anna; Meyer Zu Horste, Melissa; Cichy, Joanna; Miller, Joan W; Gragoudas, Evangelos; Vavvas, Demetrios G

    2014-07-01

    Verteporfin (VP), a benzoporphyrin derivative, is clinically used in photodynamic therapy for neovascular macular degeneration. Recent studies indicate that VP may inhibit growth of hepatoma cells without photoactivation through inhibition of YAP-TEAD complex. In this study, we examined the effects of VP without light activation on human retinoblastoma cell lines. Verteporfin but not vehicle control inhibited the growth, proliferation and viability of human retinoblastoma cell lines (Y79 and WERI) in a dose-dependent manner and was associated with downregulation of YAP-TEAD associated downstream proto-oncogenes such as c-myc, Axl, and surviving. In addition VP affected signals involved in cell migration and angiogenesis such as CTGF, cyr61, and VEGF-A but was not associated with significant effect on the mTOR/autophagy pathway. Of interest the pluripotency marker Oct4 were downregulated by Verteporfin treatment. Our results indicate that the clinically used photosensitizer VP is a potent inhibitor of cell growth in retinoblastoma cells, disrupting YAP-TEAD signaling and pluripotential marker OCT4. This study highlights for the first time the role of the YAP-TEAD pathway in Retinoblastoma and suggests that VP may be a useful adjuvant therapeutic tool in treating Rb patients. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Investigation of the Relationship Between Clinical and EEG Findings of Photosensitive Epilepsy and GABA Receptor Alpha 1 Subunit (GABRA1) Gene Mutations

    NARCIS (Netherlands)

    Yavuz, E.N.; Demirkan, A.; Moen, S.; Ozdemir, O.; Catal, S.; Bebek, N.; Ozbek, U.; Baykan, B.

    2011-01-01

    Objective: Although photosensitive epilepsy (PE) is commonly observed, its pathophysiology has not been clarified yet. However, relevant literature indicates that genetic factors play an important role. Our aim was to investigate whether there is a relationship between the clinical and

  6. Fast and effective photodynamic inactivation of multiresistant bacteria by cationic riboflavin derivatives.

    Directory of Open Access Journals (Sweden)

    Tim Maisch

    Full Text Available Photodynamic inactivation of bacteria (PIB proves to be an additional method to kill pathogenic bacteria. PIB requires photosensitizer molecules that effectively generate reactive oxygen species like singlet oxygen when exposed to visible light. To allow a broad application in medicine, photosensitizers should be safe when applied in humans. Substances like vitamin B2, which are most likely safe, are known to produce singlet oxygen upon irradiation. In the present study, we added positive charges to flavin derivatives to enable attachment of these molecules to the negatively charged surface of bacteria. Two of the synthesized flavin derivatives showed a high quantum yield of singlet oxygen of approximately 75%. Multidrug resistant bacteria like MRSA (Methicillin resistant Staphylococcus aureus, EHEC (enterohemorrhagic Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii were incubated with these flavin derivatives in vitro and were subsequently irradiated with visible light for seconds only. Singlet oxygen production in bacteria was proved by detecting its luminescence at 1270 nm. After irradiation, the number of viable bacteria decreased up to 6 log10 steps depending on the concentration of the flavin derivatives and the light dosimetry. The bactericidal effect of PIB was independent of the bacterial type and the corresponding antibiotic resistance pattern. In contrast, the photosensitizer concentration and light parameters used for bacteria killing did not affect cell viability of human keratinocytes (therapeutic window. Multiresistant bacteria can be safely and effectively killed by a combination of modified vitamin B2 molecules, oxygen and visible light, whereas normal skin cells survive. Further work will include these new photosensitizers for topical application to decolonize bacteria from skin and mucosa.

  7. Autophagy inhibition sensitizes bladder cancer cells to the photodynamic effects of the novel photosensitizer chlorophyllin e4.

    Science.gov (United States)

    Du, Lihuan; Jiang, Ning; Wang, Guozeng; Chu, Yiwei; Lin, Wei; Qian, Jing; Zhang, Yuanfang; Zheng, Jingcun; Chen, Gang

    2014-04-05

    We previously developed a novel photosensitizer, chlorophyllin e4, and found that chlorophyllin e4 mediated-PDT could kill 5637 and T24 cells by inducing apoptotic cell death. Here, we further investigated the new mechanism of autophagy and determined its relevance to apoptosis in e4-PDT. We demonstrated that chlorophyllin e4 was located in both lysosome and mitochondria, and autophagy also occurred in bladder cancer cells upon e4-PDT. More importantly, autophagy played a pro-survival role, and its inhibition enhanced e4-PDT-associated apoptotic cell death because cells pretreated with the typical autophagy inhibitor either 3-methyladenine or Bafilomycin A1 exhibited much lower cell viability and higher apoptotic cell death. Thus, these data imply that the combination of PDT, when mediated by our new photosensitizer chlorophyllin e4, and an autophagy inhibitor might be a promising approach to the eliminationof non-muscle invasive bladder cancer.

  8. Density Functional Theory Study on the Electronic Structures of Oxadiazole Based Dyes as Photosensitizer for Dye Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Umer Mehmood

    2015-01-01

    Full Text Available The molecular structures and UV-visible absorption spectra of complex photosensitizers comprising oxadiazole isomers as the π-bridges were analyzed by density functional theory (DFT and time-dependent DFT. The ground state and excited state oxidation potentials, HOMOs and LUMOs energy levels, and electron injection from the dyes to semiconductor TiO2 have been computed in vacuum here. The results show that all of the dyes may potentially be good photosensitizers in DSSC. To justify the simulation basis, N3 dye was also simulated under the similar conditions. Simulated absorption spectrum, HOMO, LUMO, and band gap values of N3 were compared with the experimental values. We also computed the electronic structure properties and absorption spectra of dye/(TiO28 systems to elucidate the electron injection efficiency at the interface. This work is expected to give proper orientation for experimental synthesis.

  9. Fungicidal response of a novel natural photosensitizer (Beta vulgaris) on Candida albicans with low-power laser radiation

    Science.gov (United States)

    Mittal, Subhangi; Roy, Sukhdev; Srivastava, J. N.

    2013-05-01

    We report the efficacy of an aqueous extract of Beta vulgaris as a novel, natural photosensitizer for use in photodynamic therapy against Candidiasis disease. This study evaluates the effect of different laser wavelengths (He-Ne: 633 nm, Nd-YAG: 532 nm), power (17, 27 mW) and duration of exposure (5, 10, 15 min) in combination with the Beta vulgaris natural photosensitizer on the viability of Candida albicans causing Candidiasis disease. Although inhibition was observed in all cases, a maximum of 51.91% inhibition takes place with the combination of Beta vulgaris exposed to 532 nm at 27 mW for 15 min by the Agar well diffusion method. The study is important in optimizing different parameters and designing a low-power, compact, non-invasive and portable device for treatment.

  10. Natural evolution from idiopathic photosensitive occipital lobe epilepsy to idiopathic generalized epilepsy in an untreated young patient.

    Science.gov (United States)

    Bonini, Francesca; Egeo, Gabriella; Fattouch, Jinan; Fanella, Martina; Morano, Alessandra; Giallonardo, Anna Teresa; di Bonaventura, Carlo

    2014-04-01

    Idiopathic photosensitive occipital lobe epilepsy (IPOE) is an idiopathic localization-related epilepsy characterized by age-related onset, specific mode of precipitation, occipital photic-induced seizures--frequently consisting of visual symptoms--and good prognosis. This uncommon epilepsy, which usually starts in childhood or adolescence, has rarely been observed in families in which idiopathic generalized epilepsy also affects other members. We describe a nuclear family in which the proband showed electro-clinical features of idiopathic photosensitive occipital lobe epilepsy in childhood, which subsequently evolved into absences and a single generalized tonico-clonic seizure in early adolescence. His mother had features suggestive of juvenile myoclonic epilepsy. This case illustrates a continuum between focal and generalized entities in the spectrum of the so-called idiopathic (genetically determined) epileptic syndromes. Copyright © 2013 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  11. Photosensitivity and line-edge roughness of novel polymer-bound PAG photoresists

    Science.gov (United States)

    Lee, Cheng-Tsung; Wang, Mingxing; Jarnagin, Nathan D.; Gonsalves, Kenneth E.; Roberts, Jeanette M.; Yueh, Wang; Henderson, Clifford L.

    2007-03-01

    Substantially improved photoresist material designs, which can provide higher photosensitivity and precise critical dimension and edge roughness control, will be required to enable the application of next generation lithography technology to the production of future sub-65 nm node IC device generations. The development and characterization of novel material platforms that solve the aforementioned basic problems with chemically amplified resists (CARs) is essential and is already one of the major subjects of modern lithography research. In that regard, we have pursued development of a variety of 193 nm and EUV CARs that contain photoacid generator (PAG) units covalently bonded directly to the resin polymer backbone. However, the detailed structure-property relationships that result from this direct attachment of the PAG functional group to the polymer have previously not yet been rigorously characterized. In this work, the lithographic properties of a polymer-bound PAG CAR (GBLMA-co-EAMA-co-F4-MBS.TPS) and its blended-PAG analog resist (GBLMA-co-EAMA blend F4-IBBS.TPS) were studied and compared. The direct incorporation of PAG functionality into the resist polymer, where the resulting photoacid remains bound to the polymer, showed improved photosensitivity, resolution, and lower LER as compared with the analogous blended-PAG resist. The improved resolution and LER were expected due to the restricted photoacid diffusion and uniform PAG distribution provided by direct incorporation of the PAG into the polymer backbone to make a single-component resist material. The ability to load higher levels of PAG into the resist provided by this PAG incorporation into the polymer, as compared to the low PAG concentrations attainable by traditional blending approaches, overcomes the sensitivity loss that should result from reduction in photoacid diffusivity and concomitant smaller acid-catalytic chain lengths. In fact, the polymer-bound PAG resist achieves a faster photospeed than

  12. Retinal Waves Modulate an Intraretinal Circuit of Intrinsically Photosensitive Retinal Ganglion Cells.

    Science.gov (United States)

    Arroyo, David A; Kirkby, Lowry A; Feller, Marla B

    2016-06-29

    Before the maturation of rod and cone photoreceptors, the developing retina relies on light detection by intrinsically photosensitive retinal ganglion cells (ipRGCs) to drive early light-dependent behaviors. ipRGCs are output neurons of the retina; however, they also form functional microcircuits within the retina itself. Whether ipRGC microcircuits exist during development and whether they influence early light detection remain unknown. Here, we investigate the neural circuit that underlies the ipRGC-driven light response in developing mice. We use a combination of calcium imaging, tracer coupling, and electrophysiology experiments to show that ipRGCs form extensive gap junction networks that strongly contribute to the overall light response of the developing retina. Interestingly, we found that gap junction coupling was modulated by spontaneous retinal waves, such that acute blockade of waves dramatically increased the extent of coupling and hence increased the number of light-responsive neurons. Moreover, using an optical sensor, we found that this wave-dependent modulation of coupling is driven by dopamine that is phasically released by retinal waves. Our results demonstrate that ipRGCs form gap junction microcircuits during development that are modulated by retinal waves; these circuits determine the extent of the light response and thus potentially impact the processing of early visual information and light-dependent developmental functions. Light-dependent functions in early development are mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs). Here we show that ipRGCs form an extensive gap junction network with other retinal neurons, including other ipRGCs, which shapes the retina's overall light response. Blocking cholinergic retinal waves, which are the primary source of neural activity before maturation of photoreceptors, increased the extent of ipRGC gap junction networks, thus increasing the number of light-responsive cells. We

  13. Polymer-lipid-PEG hybrid nanoparticles as photosensitizer carrier for photodynamic therapy.

    Science.gov (United States)

    Pramual, Sasivimon; Lirdprapamongkol, Kriengsak; Svasti, Jisnuson; Bergkvist, Magnus; Jouan-Hureaux, Valérie; Arnoux, Philippe; Frochot, Céline; Barberi-Heyob, Muriel; Niamsiri, Nuttawee

    2017-08-01

    Polymer-lipid-PEG hybrid nanoparticles were investigated as carriers for the photosensitizer (PS), 5,10,15,20-Tetrakis(4-hydroxy-phenyl)-21H,23H-porphine (pTHPP) for use in photodynamic therapy (PDT). A self-assembled nanoprecipitation technique was used for preparing two types of core polymers poly(d,l-lactide-co-glycolide) (PLGA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) with lipid-PEG as stabilizer. The resulting nanoparticles had an average particle size of 88.5±3.4nm for PLGA and 215.0±6.3nm for PHBV. Both nanoparticles exhibited a core-shell structure under TEM with high zeta potential and loading efficiency. X-ray powder diffraction analysis showed that the encapsulated pTHPP molecules in polymeric nanoparticles no longer had peaks of free pTHPP in the crystalline state. The pTHPP molecules encapsulated inside the polymeric core demonstrated improved photophysical properties in terms of singlet oxygen generation and cellular uptake rate in a FTC-133 human thyroid carcinoma cell line, compared to non-encapsulated pTHPP. The pTHPP-loaded polymer-lipid-PEG nanoparticles showed better in vitro phototoxicity compared to free pTHPP, in both time- and concentration-dependent manners. Overall, this study provides detailed analysis of the photophysical properties of pTHPP molecules when entrapped within either PLGA or PHBV nanoparticle cores, and demonstrates the effectiveness of these systems for delivery of photosensitizers. The two polymeric systems may have different potential benefits, when used with cancer cells. For instance, the pTHPP-loaded PLGA system requires only a short time to show a PDT effect and may be suitable for topical PDT, while the delayed photo-induced cytotoxic effect of the pTHPP-loaded PHBV system may be more suitable for cancer solid tumors. Hence, both pTHPP-encapsulated polymer-lipid-PEG nanoparticles can be considered promising delivery systems for PDT cancer treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. All-Optical Micro Motors Based on Moving Gratings in Photosensitive Media

    Science.gov (United States)

    Curley, M.; Sarkisov, S. S.; Fields, A.; Smith, C.; Kukhtarev, N.; Kulishov, M. B.; Adamovsky, Grigory

    2001-01-01

    An all-optical micromotor with a rotor driven by a traveling wave of surface deformation of a stator being in contact with the rotor is being studied. Instead of an ultrasonic wave produced by an electrically driven piezoelectric actuator as in ultrasonic motors, the wave is a result of a photo-induced surface deformation of a photosensitive material produced by an incident radiation. A thin piezoelectric polymer will deform more easily LiNbO3 or metal when irradiated with light. The type of photosensitive material studied are piezoelectric polymers with and without coatings for connecting electrodes. In order to be considered as a possible candidate for micromotors, the material should exhibit surface deformation produced by a laser beam of the order of 10 microns. This is compared to the deformations produced by static holographic gratings studied in photorefractive crystals of LiNbO3 using high vertical resolution surface profilometer Dektak 3 and surface interferometer WYKO. An experimental setup showing the oscillations has been developed. The setup uses a chopped beam from an Argon ion laser to produce the deformation while a probe beam is reflected by the thin film into a fiber which is then detected on an oscilloscope. A ramp voltage signal generator will drive the piezoelectric film in another experiment to determine the resonance of the film. A current is generated when light is incident upon the film and this current can be measured. The reverse process has already been demonstrated in other piezoelectric actuators. Changing voltage, polarity, and frequency of the signal can easily generate vibrations similar to those when light is incident on the film. This can be compared to the effects of laser interaction with light absorbing fluids such as solutions of 2,9,16,23-Tetrakis(phenylthio)-29H, 31 H-phthalocyanine in chlorobenzene in capillary tubes, The possibility of using a liquid with the piezoelectric film would be a novel idea for a micromotor since

  15. Lethal photosensitization of wound-associated microbes using indocyanine green and near-infrared light

    Directory of Open Access Journals (Sweden)

    Wilson Michael

    2008-07-01

    Full Text Available Abstract Background The increase in resistance to antibiotics among disease-causing bacteria necessitates the development of alternative antimicrobial approaches such as the use of light-activated antimicrobial agents (LAAAs. Light of an appropriate wavelength activates the LAAA to produce cytotoxic species which can then cause bacterial cell death via loss of membrane integrity, lipid peroxidation, the inactivation of essential enzymes, and/or exertion of mutagenic effects due to DNA modification. In this study, the effect of the LAAA indocyanine green excited with high or low intensity light (808 nm from a near-infrared laser (NIR on the viability of Staphylococcus aureus, Streptococcus pyogenes and Pseudomonas aeruginosa was investigated. Results All species were susceptible to killing by the LAAA, the bactericidal effect being dependent on both the concentration of indocyanine green and the light dose. Indocyanine green photosensitization using both high (1.37 W cm-2 and low (0.048 W cm-2 intensity NIR laser light was able to achieve reductions of 5.6 log10 (>99.99% and 6.8 log10 (>99.99% in the viable counts of Staph. aureus and Strep. pyogenes (using starting concentrations of 106–107 CFU ml-1. Kills of 99.99% were obtained for P. aeruginosa (initial concentration 108–109 CFU ml-1 photosensitized by the high intensity light (1.37 W cm-2; while a kill of 80% was achieved using low intensity irradiation (0.07 W cm-2. The effects of L-tryptophan (a singlet oxygen scavenger and deuterium oxide (as an enhancer of the life span of singlet oxygen on the survival of Staph. aureus was also studied. L-tryptophan reduced the proportion of Staph. aureus killed; whereas deuterium oxide increased the proportion killed suggesting that singlet oxygen was involved in the killing of the bacteria. Conclusion These findings imply that indocyanine green in combination with light from a near-infrared laser may be an effective means of eradicating bacteria

  16. Treatment of pesticide rinsate towards reuse by photosensitized Fenton-like process.

    Science.gov (United States)

    Kuo, W S; Ho, Y Y

    2010-01-01

    A Fenton-like process with combination of dye has been used to enhance the treatment of carbofuran (2,3-dihydro-2,2-dimethylbenzofuran -7-yl methylcarbamate) pesticide rinsate. Results showed that as compared to Fenton-like process, this photosensitization Fenton-like process improved the degradation efficiency of carbofuran rinsate significantly. Among the conditions studied, the optimum dosage for the complete destruction of carbofuran molecular structure was found under a [H2O2]0/[Fe3+]0 ratio of 30-35 and a [Dye]0/[Fe3+]0 ratio of 2%, respectively, after an irradiance of 500 W/m2 for 20 min. As a result, the COD degradation efficiency of rinsate could be promoted from 37.1 to 61.2% and 66.0% by an addition of methylene blue (MB) and alizarin red S (ARS), respectively. Nevertheless, ARS showed a much more effective acceleration effect on the mineralization and microtoxicity reduction of carbofuran than MB. A mineralization efficiency of 57.2% and a microtoxicity reduction of 90% could be achieved with the addition of ARS. Because of its quinone structure unit, the dye ARS could play a role like hydroquinone to recycle Fe2+ from Fe3+, resulting in one more catalytic effect on the reduction of Fe3+ and thus the mineralization and microtoxicity reduction of carbofuran was greatly promoted in the presence of ARS. In addition, it was found that carbofuran molecules could be decomposed quickly to lower-molecular-weight intermediates and even mineralized by attacking of hydroxyl radicals. Carbofuran was found to be decomposed to carbofuran phenol, 3-oxo carbofuran phenol, and 3-hydroxyl carbofuran phenol initially, and then further be degraded to smaller molecules, such as NO3-, CH3COOH, (COOH)2 and CO2. Accordingly, it was believed that the Fenton-like process along with the aid of a photosensitizer, such as ARS, under an appropriate ratio could be a feasible and potential technology for the treatment of pesticide rinsate.

  17. Metal-based phthalocyanines as a potential photosensitizing agent in photodynamic therapy for the treatment of melanoma skin cancer

    Science.gov (United States)

    Maduray, Kaminee; Odhav, B.

    2014-03-01

    Photodynamic therapy (PDT) is an emerging medical treatment that uses photosensitizers (drug) which are activated by laser light for the generation of cytotoxic free radicals and singlet oxygen molecules that cause tumor cell death. In the recent years, there has been a focus on using and improving an industrial colorant termed phthalocyanines as a prospective photosensitizer because of its unique properties. This in vitro study investigated the photodynamic effect of indium (InPcCl) and iron (FePcCl) phthalocyanine chlorides on human skin cancer cells (melanoma). Experimentally, 2 x 104 cells/ml were seeded in 24-well tissue culture plates and allowed to attach overnight, after which cells were treated with different concentrations (2 μg/ml - 100 μg/ml) of InPcCl and FePcCl. After 2 h, cells were irradiated with constant light doses of 2.5 J/cm2, 4.5 J/cm2 and 8.5 J/cm2 delivered from a diode laser. Post-irradiated cells were incubated for 24 h before cell viability was measured using the MTT Assay. At 24 h after PDT, irradiation with a light dose of 2.5 J/cm2 for each photosensitizing concentration of InPcCl and FePcCl produced a significant decrease in cell viability, but when the treatment light dose was further increased to 4.5 J/cm2 and 8.5 J/cm2 the cell survival was less than 55% for photosensitizing concentrations of InPcCl and FePcCl from 4 μg/ml to 100 μg/ml. This PDT study concludes that low concentrations on InPcCl and FePcCl activated with low level light doses can be used for the effective in vitro killing of melanoma cancer cells.

  18. Photosensitive Pt(IV)-azide prodrug-loaded nanoparticles exhibit controlled drug release and enhanced efficacy in vivo.

    Science.gov (United States)

    Xiao, Haihua; Noble, Gavin T; Stefanick, Jared F; Qi, Ruogu; Kiziltepe, Tanyel; Jing, Xiabin; Bilgicer, Basar

    2014-01-10

    Cisplatin has long been the first line of treatment for a variety of solid tumors. However, poor pharmacokinetics and high incidences of resistance in the clinic have motivated the production of numerous alternative Pt-based anticancer species. Recently, photosensitive Pt(IV) complexes have garnered much interest because they offer a method of selective induction of active Pt(II) at the tumor site by UVA irradiation. Here, we report the first synthesis, in vitro and in vivo characterization of a novel series of photosensitive Pt(IV)–azide prodrugs and micellar nanoparticle formulations thereof. Upon mild UVA irradiation, both free Pt(IV) complexes and micellar nanoparticles rapidly released biologically active Pt(II), capable of binding to 5′-GMP,while remaining extremely stable in the dark. In vitro, uptake of photosensitive Pt(IV) prodrugs by ovarian cancer SKOV-3 cells was greatly enhanced with the micellar nanoparticles compared to their free prodrug analogs, as well as cisplatin and oxaliplatin. Increased cytotoxicity was observed upon UVA treatment, with up to a 13-fold enhancement over oxaliplatin for the micellar nanoparticles. In vivo bioavailability of micellar nanoparticles was enhanced ~10 fold over free Pt(IV) prodrugs. Importantly, micellar nanoparticles demonstrated significantly improved efficacy against H22 murine hepatocarcinoma, showing decreased systemic toxicity and increased tumor growth inhibition relative to small molecule drugs. These findings establish that photosensitive Pt(IV) complexes, specifically when formulated into micellar nanoparticles, have the potential to offer a robust platform for the controlled delivery and selective activation of Pt-based anticancer therapeutics.

  19. Activatable albumin-photosensitizer nanoassemblies for triple-modal imaging and thermal-modulated photodynamic therapy of cancer.

    Science.gov (United States)

    Hu, Dehong; Sheng, Zonghai; Gao, Guanhui; Siu, Fungming; Liu, Chengbo; Wan, Qian; Gong, Ping; Zheng, Hairong; Ma, Yifan; Cai, Lintao

    2016-07-01

    Photodynamic therapy (PDT) is a noninvasive and effective approach for cancer treatment. The main bottlenecks of clinical PDT are poor selectivity of photosensitizer and inadequate oxygen supply resulting in serious side effects and low therapeutic efficiency. Herein, a thermal-modulated reactive oxygen species (ROS) strategy using activatable human serum albumin-chlorin e6 nanoassemblies (HSA-Ce6 NAs) for promoting PDT against cancer is developed. Through intermolecular disulfide bond crosslinking and hydrophobic interaction, Ce6 photosensitizer is effectively loaded into the HSA NAs, and the obtained HSA-Ce6 NAs exhibit excellent reduction response, as well as enhanced tumor accumulation and retention. By the precision control of the overall body temperature instead of local tumor temperature increasing from 37 °C to 43 °C, the photosensitization reaction rate of HSA-Ce6 NAs increases 20%, and the oxygen saturation of tumor tissue raise 52%, significantly enhancing the generation of ROS for promoting PDT. Meanwhile, the intrinsic fluorescence and photoacoustic properties, and the chelating characteristic of porphyrin ring can endow the HSA-Ce6 NAs with fluorescence, photoacoustic and magnetic resonance triple-modal imaging functions. Upon irradiation of low-energy near-infrared laser, the tumors are completely suppressed without tumor recurrence and therapy-induced side effects. The robust thermal-modulated ROS strategy combined with albumin-based activatable nanophotosensitizer is highly potential for multi-modal imaging-guided PDT and clinical translation.

  20. Extracellular talaporfin sodium-induced photosensitization reaction with various albumin animal species on myocardial cells in vitro

    Science.gov (United States)

    Ogawa, Emiyu; Arai, Tsunenori

    2017-02-01

    It is reported that the albumin has different structure among animal species. We have proposed a new methodology of cardiac ablation using talaporfin sodium-induced photosensitization reaction with short drug-light interval to realize immediate and permanent therapeutic effect by singlet oxygen production mainly in the interstitial space. The photosensitization reaction efficacy with different animal species should be investing to consider the optimal animal therapeutic model to evaluate the therapeutic effect of new cardiac ablation methodology. We studied the cell-killing efficacy of extracellular talaporfin sodium-induced photosensitization reaction using talaporfin sodium on myocardial cells in vitro with different albumin animal species: human, canine, bovine, and porcine serum albumin. We obtained that the albumin concentration tendency on the binding ratio and cell lethality was different among the animal species but there was no correlation between binding ratio and cell lethality. We found that the cell lethality dependence on albumin concentration showed 2 different groups, human-canine and bovine-porcine. We think that the canine might be useful as a therapeutic animal model since the cytotoxicity tendency on albumin concentration was similar with that of human albumin. These cell lethality tendency difference would be suggested to explain by the existence of the diazepam site that talaporfin sodium binds mainly.

  1. Effect of soybean lecithin on iron-catalyzed or chlorophyll-photosensitized oxidation of canola oil emulsion.

    Science.gov (United States)

    Choe, Jeesu; Oh, Boyoung; Choe, Eunok

    2014-11-01

    The effect of soybean lecithin addition on the iron-catalyzed or chlorophyll-photosensitized oxidation of emulsions consisting of purified canola oil and water (1:1, w/w) was studied based on headspace oxygen consumption using gas chromatography and hydroperoxide production using the ferric thiocyanate method. Addition levels of iron sulfate, chlorophyll, and soybean lecithin were 5, 4, and 350 mg/kg, respectively. Phospholipids (PLs) during oxidation of the emulsions were monitored by high performance liquid chromatography. Addition of soybean lecithin to the emulsions significantly reduced and decelerated iron-catalyzed oil oxidation by lowering headspace oxygen consumption and hydroperoxide production. However, soybean lecithin had no significant antioxidant effect on chlorophyll-photosensitized oxidation of the emulsions. PLs in soybean lecithin added to the emulsions were degraded during both oxidation processes, although there was little change in PL composition. Among PLs in soybean lecithin, phosphatidylethanolamine and phosphatidylinositol were degraded the fastest in the iron-catalyzed and the chlorophyll-photosensitized oxidation, respectively. The results suggest that addition of soybean lecithin as an emulsifier can also improve the oxidative stability of oil in an emulsion. © 2014 Institute of Food Technologists®

  2. ProTEK PSB as Biotechnology Photosensitive Protection Mask on 3C-SiC-on-Si in MEMS Sensor

    Science.gov (United States)

    Marsi, N.; Majlis, B. Y.; Mohd-Yasin, F.; Hamzah, A. A.; Mohd Rus, A. Z.

    2016-11-01

    This project presents the fabrication of MEMS employing a cubic silicon carbide (3C- SiC) on silicon wafer using newly developed ProTEK PSB as biotechnology photosensitive protection mask. This new biotechnology can reduce the number of processes and simplify the process flow with minimal impact on overall undercut performance. The 680 pm thick wafer is back-etched, leaving the 3C-SiC thin film with a thickness of 1.0 μm as the flexible diaphragm to detect pressure. The effect of the new coating of ProTEK PSB on different KOH solvents were investigated depending on various factors such as development time, final cure temperature and the thickness of the ProTEK PSB deposited layer. It is found that 6.174 μm thickness of ProTEK PSB offers some possibility of reducing the processing time compared to silicon nitride etch masks in KOH (55%wt, 80°C). The new ProTEK PSB biotechnology photosensitive protection mask indicates good stability and sustains its performance in different treatments under KOH and IPA for 8 hours. This work also revealed that the fabrication of MEMS sensors using the new biotechnology photosensitive protection mask provides a simple assembly approach and reduces manufacturing costs. The MEMS sensor can operate up to 500 °C as indicated under the sensitivity of 0.826 pF/MPa with nonlinearity and hysteresis of 0.61% and 3.13%, respectively.

  3. Studies on the preparation and the photoelectrochemical properties of the nanoporous titania films attached with and without photosensitizer TCPP

    Indian Academy of Sciences (India)

    Yun-Lan Gong; Fei-Hui Li; Fei Lu; Chang Dai

    2015-08-01

    Fabrication of TiO2 nanoporous films was carried out by anodic oxidation using two-step voltage mode while the subsequent attaching of the photosensitizer 5,10,15,20-tetra(4-carboxyphenyl) porphyrin (TCPP) on the prepared TiO2 nanoporous films was carried out by the electrochemical method. Photoelectrochemical properties of TiO2 nanoporous films attached with and without photosensitizer TCPP were analysed by fluorescence spectroscopy and electrochemical test. Effects of process parameters on the photoelectrochemical properties of TiO2 nanoporous films were also investigated. The optimized process parameters for the preparation of TiO2 nanoporous films with the best photoelectrochemical property can be concluded as follows: oxidation potentials is 70–140 V, oxidation temperature is 25°C, H2SO4 electrolyte concentration is 0.5 mol l−1 and oxidation time is 60 min. The results also show that attaching of the photosensitizer TCPP on the TiO2 nanoporous films can indeed improve the properties of TiO2 nanoporous films, and the optimized attaching temperature and attaching voltage are 25°C and 60 V, respectively.

  4. Comparison of Riboflavin and Toluidine Blue O as Photosensitizers for Photoactivated Disinfection on Endodontic and Periodontal Pathogens In Vitro.

    Science.gov (United States)

    Nielsen, Henrik Krarup; Garcia, Javier; Væth, Michael; Schlafer, Sebastian

    2015-01-01

    Photoactivated disinfection has a strong local antimicrobial effect. In the field of dentistry it is an emerging adjunct to mechanical debridement during endodontic and periodontal treatment. In the present study, we investigate the effect of photoactivated disinfection using riboflavin as a photosensitizer and blue LED light for activation, and compare it to photoactivated disinfection with the widely used combination of toluidine blue O and red light. Riboflavin is highly biocompatible and can be activated with LED lamps at hand in the dental office. To date, no reports are available on the antimicrobial effect of photoactivated disinfection using riboflavin/blue light on oral microorganisms. Planktonic cultures of eight organisms frequently isolated from periodontal and/or endodontic lesions (Aggregatibacter actinomycetemcomitans, Candida albicans, Enterococcus faecalis, Escherischia coli, Lactobacillus paracasei, Porphyromonas gingivalis, Prevotella intermedia and Propionibacterium acnes) were subjected to photoactivated disinfection with riboflavin/blue light and toluidine blue O/red light, and survival rates were determined by CFU counts. Within the limited irradiation time of one minute, photoactivated disinfection with riboflavin/blue light only resulted in minor reductions in CFU counts, whereas full kills were achieved for all organisms when using toluidine blue O/red light. The black pigmented anaerobes P. gingivalis and P. intermedia were eradicated completely by riboflavin/blue light, but also by blue light treatment alone, suggesting that endogenous chromophores acted as photosensitizers in these bacteria. On the basis of our results, riboflavin cannot be recommended as a photosensitizer used for photoactivated disinfection of periodontal or endodontic infections.

  5. Photosensitized methyl paraben induces apoptosis via caspase dependent pathway under ambient UVB exposure in human skin cells.

    Science.gov (United States)

    Dubey, Divya; Chopra, Deepti; Singh, Jyoti; Srivastav, Ajeet K; Kumari, Smita; Verma, Ankit; Ray, Ratan Singh

    2017-10-01

    Methyl paraben (MP), is a widely used preservative in pharmaceutical, food and cosmetic products. Its molecular mechanism under ambient ultraviolet radiation is not well understood. We investigated photosensitizing mechanism of MP under ambient UVB (0.6 mW/cm(2)) intensity. MP showed dose dependent decrease in cell viability of human keratinocyte cell line (HaCaT) by MTT and NRU assays. Study showed 40% reduction in antimicrobial activity of UVB irradiated MP through E. coli culture. Photosensitized MP (25 μg/ml) significantly enhanced lipid peroxidation, intracellular ROS generation and disrupted mitochondrial membrane integrity. MP induced loss of lysosomal membrane integrity and endoplasmic reticulum (ER) mediated stress evident from Ca(+2) release. Phototoxicity of MP showed nuclear fragmentation, phosphatidylserine translocation, 30% tail DNA and micronuclei formation. Study showed mitochondria mediated apoptosis via upregulation of Bax, Apaf-1, Cytochrome C and Caspase-3. Upregulation of Caspase-12 (2 folds) specifically showed role of ER in apoptosis. Specific caspase inhibitor, Z-VAD-FMK showed involvement of caspase cascade pathway in apoptosis. Results indicate that photosensitive MP leads to oxidative stress mediated DNA damage and apoptosis through mitochondria and ER. MP causes deleterious effects and its long term exposure to human skin may promote skin diseases. Therefore, MP should be replaced by other photosafe preservatives for humans. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Fumonisin B1 does not prevent apoptosis in A431 human epidermoid carcinoma cells after photosensitization with a silicon phthalocyanine.

    Science.gov (United States)

    Nagy, B; Chiu, S M; Separovic, D

    2000-09-01

    Photodynamic therapy with the phthalocyanine photosensitizer Pc 4 (Pc 4-PDT), an apoptosis inducer, is associated with accumulation of ceramide in various cell lines. The role of ceramide in Pc 4-PDT-induced apoptosis was investigated in A431 cells. Caspase-3 (casp-3) was activated and TUNEL positive cells began to appear 30 and 60 min post-Pc 4-PDT, respectively. A rapid increase (10 min) in cellular ceramide levels was observed after Pc 4-PDT. Induced ceramide accumulation was maintained over 60 min, Acid sphingomyelinase, a ceramide-generating enzyme, was inhibited after photosensitization with Pc 4, suggesting that the enzyme was not required for stimulated ceramide accumulation. Co-treatment of A431 cells with fumonisin B1, a ceramide synthase inhibitor, and Pc 4-PDT led to a decrease in ceramide levels without any effect on induced casp-3 activity or apoptosis. In the presence of zVAD, a pan-caspase inhibitor, apoptosis was abolished, while ceramide levels remained elevated after Pc 4-PDT. Exposure of A431 cells to exogenous C6-ceramide for 22 h, led to induction of apoptosis, and the process was abrogated by zVAD. In conclusion, C6-ceramide-, like Pc 4-PDT-induced apoptosis, is zVAD-sensitive. Furthermore, Pc 4 photosensitization can lead to apoptosis without FB-sensitive elevation in ceramide levels upstream of caspases.

  7. Enhanced photosensitized degradation of rhodamine B on CdS/TiO{sub 2} nanocomposites under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wenjuan [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Sciences and Engineering, Nanjing University of Information Sciences and Engineering, Nanjing 210044 (China); Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Shandong Province Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu 273165 (China); Cui, Xiaoli [Shandong Province Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu 273165 (China); Wang, Peixian; Shao, Yu [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Li, Danzhen, E-mail: dzli@fzu.edu.cn [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Teng, Fei [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Sciences and Engineering, Nanjing University of Information Sciences and Engineering, Nanjing 210044 (China)

    2013-09-01

    Graphical abstract: The photosensitized degradation of RhB was largely enhanced by the synergistic effect of the RhB and CdS/TiO{sub 2} nanocomposite. The composite of the two inorganic semiconductors with appropriate oxidation reduction energy levels enhanced the charge separation and extended the absorption response to visible region. - Highlights: • CdS/TiO{sub 2} nanocomposites were synthesized by a simple hydrothermal method. • Samples prepared at 200 °C, 12 h, CdS/TiO{sub 2} = 12% possessed the best activity. • The photosensitized degradation of RhB was largely enhanced by the composite. • The better activity was due to the synergistic effect of the RhB and CdS/TiO{sub 2}. - Abstract: Visible-light-driven photocatalysts, CdS/TiO{sub 2} nanocomposites were synthesized by a simple hydrothermal method. Their formation and structures were characterized by X-ray diffractometer, transmission electron microscopy, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. Taking rhodamine B (RhB) as a model, their photocatalytic activities in aqueous phase under visible light irradiation (420 < λ < 800 nm) were tested. The results showed that the composite of CdS and TiO{sub 2} with appropriate oxidation reduction energy levels enhanced the charge separation and extended the absorption response into visible light region. Thus, the photosensitized degradation of RhB was largely enhanced. The degradation mechanism was explored concretely.

  8. Hemoglobin derivatives

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003371.htm Hemoglobin derivatives To use the sharing features on this page, please enable JavaScript. Hemoglobin derivatives are altered forms of hemoglobin . Hemoglobin is ...

  9. Assessment of DNA Damage after Photodynamic Therapy Using a Metallophthalocyanine Photosensitizer

    Directory of Open Access Journals (Sweden)

    A. El-Hussein

    2012-01-01

    Full Text Available Photodynamic therapy (PDT is a chemotherapeutic approach that utilizes a bifunctional reagent, a photosensitizer (PS that localizes to the target tissue relative to the surrounding tissue and is toxic when exposed to laser light. PDT rapidly induces cell death, inflammatory and immune reactions, and damage of the microvasculature. DNA damage results from a variety of factors including UV-light, X-rays, ionizing radiation, toxins, chemicals, or reactive oxygen species. The aim of this study was to determine the effect of PDT as well as the influence of presensitization leading to the adaptive response (AR on the integrity of DNA. Lung (A549, breast (MCF-7, and esophageal (SNO cancer cells and Zn sulfophthalocyanine as PS with irradiation conditions of 10 J/cm2 at 636 nm were used. Subcellular localization of PS, cell morphology, and viability after PDT and DNA damage were determined. A significant decrease in viability and marked DNA damage was observed in all 3 cancer cell types in response to PDT while the adaptive response was demonstrated to significantly decrease the effectiveness of the PDT.

  10. Two different approaches in skin cancer therapy: using a photosensitizer/a natural product

    Science.gov (United States)

    Abraham, Annie; Gayathri, Devi D.; Cibin, T. R.; Ramaiah, D.

    2010-02-01

    This paper deals with two potential modes for the treatment of skin cancer-one a novel approach using a squaraine dye and the other using a natural product- the flavonoid fraction of Saraca asoka. Squaraine dye is a photosensitizing agent, which is preferentially taken up and retained by the tumor cells and when irradiated with high power visible light results in the selective destruction of the tumor cells by photodynamic therapy. The uniqueness of this mode of treatment lies in the selective destruction of tumor cells without affecting the neighbouring normal cells, which is much advantageous over radiation therapy now frequently used. The chemopreventive and therapeutic effects of the plant component are explored as well. The experimental models were Swiss albino mice in which skin tumor was induced by DMBA. Marked reduction in tumor volume and burden in the treated groups were observed. The reversal of biochemical enzyme markers like rhodanese, myeloperoxidase, β-D glucuronidase, lactate dehydrogenase, hexokinase and sialic acid to near normal levels were observed in the PDT and flavonoid fraction treated groups. The live photographs of the experimental animals and histopathological data further support the obtained results. The study assumes importance as it combines a traditional treatment mode and a novel aspect in cancer therapy using the same experimental models. Also this is the first report on PDT using a squaraine dye for skin cancer therapy in vivo.

  11. Microscopic Photosensitization: A New Tool to Investigate the Role of Mitochondria in Cell Death

    Directory of Open Access Journals (Sweden)

    May-Ghee Lum

    2002-01-01

    Full Text Available Active involvement of mitochondria in cell death has been well-documented, but local apoptotic signaling between subsets of mitochondria has been poorly explored to date. Using mitochondrially localized CMXRos as a photosensitizer coupled to laser irradiation by confocal laser scanning microscopy, we demonstrate that partial irradiation of about half the mitochondria in human 143B TK– cells induces rapid loss of mitochondrial membrane potential (ΔΨm in nonirradiated mitochondria. Cells so partially irradiated show apoptotic indications, including mobilization of cytochrome c and binding of annexin V within 2 h following irradiation. The loss of ΔΨm in nonirradiated mitochondria did not occur in cells photoirradiated in the absence of CMXRos. Increasing the proportion of irradiated mitochondria in each cell (up to about 50% generated a correspondingly greater percentage of cells in which nonirradiated mitochondria lost ΔΨm and which also showed apoptotic indications. Only at the highest level of irradiation (global for all mitochondria in one cell were signs of necrosis evident (judged by uptake of propidium iodide. Because laser irradiation is specific to the subpopulation of mitochondria targeted, the data imply that a signal emanating from irradiated mitochondria is processed by their nonirradiated counterparts. We conclude that intermitochondrial signaling occurs in the subcellular response to induction of apoptosis.

  12. Photosensitizer Adhered to Cell Culture Microplates Induces Phototoxicity in Carcinoma Cells

    Directory of Open Access Journals (Sweden)

    Verena Ziegler

    2013-01-01

    Full Text Available In vitro experiments in plastic receptacles are the basis of characterization of new photosensitizers (PSs for the photodynamic therapy. We recently reported that lipophilic PSs adhere to cell culture microplates in a kinetic-like manner (Engelhardt et al., 2011. In the current study, we examined the interaction and phototoxic effects of the microplate-adhered PS in cancer cells. Therefore, we preloaded microplates with hypericin, Foscan, PVP-hypericin, or aluminum (III phthalocyanine tetrasulfonate chloride (AlPCS4 for 24 hours and measured the PS distribution after addition of A431 human carcinoma cells: following another 24 hours up to 68% of hypericin were detected in the cell fraction. The hydrophilic PVP-hypericin and AlPCS4 also diffused into the cells, but the quantities of PS adherence were considerably lower. Microplate-adhered Foscan appeared not to be redistributed. In contrast to the hydrophilic PSs, the cellular phototoxicity of microplate-adhered lipophilic PS was high, independent of whether the PS (i was pre-loaded onto microplates or (ii added simultaneously with the cells or (iii one day after cell seeding. Based on these results, we suggest testing lipophilic PS dyes for their adherence to microplates. Furthermore, the ability of plastic materials to (reversibly store PSs might represent a new approach for the PS delivery or the development of antimicrobial coatings.

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

    Science.gov (United States)

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

    2017-02-01

    Gold nanostructures of two different shapes (spheres and rods) were synthesized to form a colloidal hybrid system with 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin tosylate salt (H2TM4PyP(OTs)4) (POR) for applications in photodynamic therapy (PDT) using light in the visible spectral range. Electron paramagnetic resonance (EPR) experiments in combination with spin trapping were used for the detection of reactive oxygen species (ROS) and evaluation of the efficiency of these novel hybrid systems as photosensitizers. It is shown that the hybrid system consisting of gold nanorods (AuNR) and porphyrin (POR) is by far more efficient than its isolated components. This enhanced efficiency is explained by a synergetic effect between the AuNR and the porphyrin, wherein a rapid energy transfer from the former to the latter produces a large amount of singlet oxygen followed by its conversion into hydroxyl radicals. The mechanism was investigated using different spin traps and different ROS inhibitors. On the other hand, spherical gold nanoparticles (AuNP) do not show this synergetic effect. The synergetic effect for gold nanorods/POR hybrid is attributed to a larger field enhancement close to the gold nanorod surface in addition to the electrostatic attraction between the components of the hybrid system. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Glycophthalocyanines as photosensitizers for triggering mitotic catastrophe and apoptosis in cancer cells.

    Science.gov (United States)

    Soares, Ana R M; Neves, Maria G P M S; Tomé, Augusto C; Iglesias-de la Cruz, M Carmen; Zamarrón, Alicia; Carrasco, Elisa; González, Salvador; Cavaleiro, José A S; Torres, Tomás; Guldi, Dirk M; Juarranz, Angeles

    2012-04-16

    Photodynamic therapy (PDT) is a treatment modality for different forms of cancer based on the combination of light, molecular oxygen, and a photosensitizer (PS) compound. When activated by light, the PS generates reactive oxygen species leading to tumor destruction. Phthalocyanines are compounds that have already shown to be efficient PSs for PDT. Several examples of carbohydrate substituted phthalocyanines have been reported, assuming that the presence of carbohydrate moieties could improve their tumor selectivity. This work describes the photoeffects of symmetric and asymmetric phthalocyanines with D-galactose (so-called GPh1, GPh2, and GPh3) on HeLa carcinoma cells and their involvement in cell death. Photophysical properties and in vitro photodynamic activities for the compounds considered revealed that the asymmetric glycophthalocyanine GPh3 is very efficient and selective, producing higher photocytotoxicity on cancer cells than in nonmalignat HaCaT. The cell toxiticy after PDT treatment was dependent upon light exposure level and GPh3 concentration. GPh3 causes cell cycle arrest at the metaphase stage leading to multiple spindle poles, mitotic catastrophe, followed by apoptosis in cancer cells. These effects were partially negated by the pancaspase inhibitor Z-VAD-FMK. Together, these results indicate that GPh3 is an excellent candidate drug for PDT, able to induce selective tumor cell death.

  15. Atmospheric organic-phase photo-sensitized epoxidation of alkenes by α-dicarbonyls

    Directory of Open Access Journals (Sweden)

    G. Yu

    2012-06-01

    Full Text Available We report a new pathway of epoxide formation in organic phases via catalytic oxidation of alkenes by air with α-dicarbonyls as photo-sensitizers. Epoxide yields as high as 100% in 30 min of exposure to a solar simulator operating at the equivalent of 48.5° zenith angle are observed. The rate constants are proportional to light intensity and inversely proportional to temperature. The reaction rate is 0th order with respect to alkenes, implying that alkenes with small concentrations may rapidly be converted to epoxides in the organic phase. Based on a statistical estimate of α-dicarbonyl concentrations in secondary organic aerosol, we propose that this reaction could be highly effective under ambient conditions: the 0th-order lifetimes of organic-phase alkenes are estimated to be as low as 10 min, significantly shorter than their gas-phase 1st-order lifetimes, which are typically hours to days. The formation of epoxides in organic particles is expected to increase their hygroscopicity and ability to act as cloud condensation nuclei. Epoxides in deliquesced particles can subsequently form polyalcohols, oligomers, organosulphates and organonitrates, increasing the organic mass in the atmospheric waters.

  16. Caffeine metabolites not caffeine protect against riboflavin photosensitized oxidative damage related to skin and eye health.

    Science.gov (United States)

    Scurachio, R S; Mattiucci, F; Santos, W G; Skibsted, L H; Cardoso, D R

    2016-10-01

    Caffeine metabolites were found to bind riboflavin with dissociation constant in the millimolar region by an exothermic process with positive entropy of reaction, which was found by (1)H NMR and fluorescence spectroscopy to occur predominantly by hydrogen bonding with water being released from riboflavin solvation shell upon caffeine metabolite binding to riboflavin. The caffeine metabolites 1-methyl uric acid and 1,7-dimethyl uric acid were shown by transient absorption laser flash photolysis to be efficient as quenchers of triplet riboflavin with second-order rate constant of 1.4 10(8)Lmol(-1)s(-1) and 1.0 10(8)Lmol(-1)s(-1), respectively, in aqueous solution of pH6.4 at 25°C and more efficient than the other caffeine metabolite 1,7-dimethyl xanthine with second-order rate constant of 4.2 10(7)Lmol(-1)s(-1). Caffeine was in contrast found to be non-reactive towards triplet riboflavin. Caffeine metabolites rather than caffeine seem accordingly important for the observed protective effect against cutaneous melanoma identified for drinkers of regular but not of decaffeinated coffee. The caffeine metabolites, but not caffeine, were by time resolved single photon counting found to quench singlet excited riboflavin through exothermic formation of ground-state precursor complexes indicating importance of hydrogen bounding through keto-enol tautomer's for protection of oxidizable substrates and sensitive structures against riboflavin photosensitization.

  17. Effects of light energy and reducing agents on C60-mediated photosensitizing reactions.

    Science.gov (United States)

    Quinones, Michael; Zhang, Yazhou; Riascos, Penelope; Hwang, Huey-Min; Aker, Winfred G; He, Xiaojia; Gao, Ruomei

    2014-01-01

    Many biomolecules contain photoactive reducing agents, such as reduced nicotinamide adenine dinucleotide (NADH) and 6-thioguanine (6-TG) incorporated into DNA through drug metabolism. These reducing agents may produce reactive oxygen species under UVA irradiation or act as electron donors in various media. The interactions of C60 fullerenes with biological reductants and light energy, especially via the Type-I electron-transfer mechanism, are not fully understood although these factors are often involved in toxicity assessments. The two reductants employed in this work were NADH for aqueous solutions and 6-TG for organic solvents. Using steady-state photolysis and electrochemical techniques, we showed that under visible light irradiation, the presence of reducing agents enhanced C60 -mediated Type-I reactions that generate superoxide anion (O2(.-)) at the expense of singlet oxygen ((1)O2) production. The quantum yield of O2(.-) production upon visible light irradiation of C60 is estimated below 0.2 in dipolar aprotic media, indicating that the majority of triplet C60 deactivate via Type-II pathway. Upon UVA irradiation, however, both C60 and NADH undergo photochemical reactions to produce O2(.-), which could lead to a possible synergistic toxicity effects. C60 photosensitization via Type-I pathway is not observed in the absence of reducing agents. © 2013 The American Society of Photobiology.

  18. ZnO nanoparticles as a luminescent down-shifting layer for photosensitive devices

    Institute of Scientific and Technical Information of China (English)

    Zhu Yao; A.Apostoluk; Liu Shibin; S.Daniele; B.Masenelli

    2013-01-01

    The optical properties of ZnO nanoparticles (NPs) fabricated by three different methods were studied by the UV-excited continuous wave photoluminescence in order to estimate their down-shifting (DS) efficiency Such a luminescent layer modifies the incident solar radiation via emitting wavelengths better matching the spectral response of the underlying photosensitive device (photodiode),thereby increasing its efficiency.Some of the studied ZnO NPs were subsequently deposited on the front side of commercial silicon photodiodes and the external quantum efficiency (EQE) characteristics of the final devices were measured.Through comparison of the photodiode's EQE characteristics before and after the deposition of the ZnO NPs layer,it was concluded that for the photodiode with a low UV sensitivity (about 8%),the ZnO luminescent layer produces a down-shifting effect and the EQE in the UV and blue range improves by 16.6%,while for the photodiodes with a higher initial UV sensitivity (about 50%),the EQE in this range decreases with the ZnO layer thickness,due to the effects competing with DS,like the diminution of the ZnO layer transmittance and an increasing diffusion.

  19. A comparative study of the photosensitizing characteristics of some cyanine dyes.

    Science.gov (United States)

    Delaey, E; van Laar, F; De Vos, D; Kamuhabwa, A; Jacobs, P; de Witte, P

    2000-03-01

    The present work has been carried out to explore the potential application of cyanines in photodynamic therapy. After photosensitization, the in vitro cytotoxic and antiproliferative activity on HeLa cells of a total of 35 cyanines belonging to several chemical subgroups is explored. Most of these cyanines have never been used before in similar experimental work. From a first set of experiments, it is found that none of the krypto-, oxa- and imidacyanines is photobiologically active on HeLa cells. Conversely, five thiacyanines (Thiacl-5), one rhodacyanine (Rhodac) and four indocyanines (Indoc2, Indoc4, Indoc5, Indoc7) show photodependent cytotoxicity or antiproliferative effects. A more detailed study shows that out of the ten selected compounds, eight cyanines feature significant photodependent cytotoxic and antiproliferative effects. All possess maximum absorption ranges between 545 and 824 nm. In particular, Rhodac, a tetramethinemeromonomethine rhodacyanine dye with an absorption maximum of 655 nm (ethanol) and a molar absorption coefficient epsilon = 108000 shows very promising photo-dependent biological activity. In general, the measured singlet oxygen quantum yield of the selected cyanines is low (cyanines with a partition coefficient close to 1.5 accumulate to the highest extent in HeLa cells, while the more hydrophobic compounds (e.g., indocyanines) concentrate less intracellularly.

  20. Highly sensitive surface plasmon resonance sensor utilizing a long period grating with photosensitive cladding.

    Science.gov (United States)

    Li, Zhihong; Chen, Tao; Zhang, Zhaogang; Zhou, Yanming; Li, Dan; Xie, Zhong

    2016-02-20

    In this study, we propose and investigate a novel grating-assisted surface plasmon resonance (SPR) platform based on a silver coated long period fiber grating having a photosensitive cladding (C-LPFG). We show that the SPR mode is transited from the higher EH mode with an effective refractive index (ERI) close to that of the surrounding refractive index (SRI) and is highly sensitive to a change in the SRI. Compared with a conventional SPR sensor, a much higher sensitivity is obtained for the novel C-LPFG-based SPR sensor. The sensitivity can be further improved by reducing the fiber diameter. The numerical results show that the highest local sensitivity, which can be as high as ∼4900  nm/RIU, and the corresponding resolution of ∼2.04×10(-6)  RIU are achieved for the reduced silver coated C-LPFG sensor. Moreover, the Q-factor and the figure of merit exhibit better characteristics than those of the conventional LPFG-based SPR sensor. Our findings provide insight into the C-LPFG-based SPR platform being a potentially important area to explore for biochemical sensing.

  1. Hologram multiplexing in a highly photosensitive photopolymerizable material in a sol-gel matrix

    Science.gov (United States)

    Murciano, A.; Blaya, S.; Carretero, L.; Ulibarrena, M.; Fimia, A.

    2005-07-01

    In this paper, we present a photopolymerizable material in a sol-gel matrix suitable for recording a large number of multiplexed diffraction gratings with low total exposure energy. The matrix of this material is an inorganic porous silica glass, a material that does not shrink when radical photopolymerization is initiated. The photosensitive component is based on acrylamide, N,N‧-methylenebisacrylamide, triethanolamine and yellow eosine as a photoinitiator. In the reported study, 50 holograms were angularly multiplexed with diffraction efficiencies between 0.1 and 1.9% resulting in a dynamic range of M/# = 3.9. The total exposure was 4.5 mJ/cm2 and the energy used in recording each hologram was 95 μJ/cm2. This indicates a very high sensitivity for this material in the range of 3.3 to 15.5 cm/mJ. Due to this good holographic performance, the material is suitable for holographic data storage applications.

  2. The photoreduction and photosensitized reduction of dyes bound to a surfactant micellar surface

    Energy Technology Data Exchange (ETDEWEB)

    Usui, Y.; Saga, K.

    1982-10-01

    The photochemical reduction of thionine(Th) and Methylene Blue(MB) bound to anionic sodium dodecyl sulfate(SDS) micelles in an aqueous solution was inhibited at the lower concentration range of a reductant anion, EDTA, because of the electrostatic repulsion between the micelles and the reductant. The concentration dependence of EDTA on the quantum yield of photoreduction has shown to be, anomalously a sigmoidal type: this is explained by mechanistic interpretation based on the cooperative effects of the ionic strength and the essential concentration of EDTA. The enhancement effect for the quantum yield of the photoreduction of eosine bound to a cationic micelle by the EDTA anion was conversely observed, because of the electrostatic attraction. When 10-dodecyl) (Acridine Orange) was incorporated into SDS micelles in water containing EDTA and ascorbic acid, and the mixture was excited, the photosensitized reduction reduction of MB bound to the micelles occurred. It was found that the quantum yield of the sensitized reduction depended on the concentration of MB and was larger than the yield on the direct excitation of MB.

  3. Photosensitive-polyimide based method for fabricating various neural electrode architectures

    Directory of Open Access Journals (Sweden)

    Yasuhiro X Kato

    2012-06-01

    Full Text Available An extensive photosensitive polyimide (PSPI-based method for designing and fabricating various neural electrode architectures was developed. The method aims to broaden the design flexibility and expand the fabrication capability for neural electrodes to improve the quality of recorded signals and integrate other functions. After characterizing PSPI’s properties for micromachining processes, we successfully designed and fabricated various neural electrodes even on a non-flat substrate using only one PSPI as an insulation material and without the time-consuming dry etching processes. The fabricated neural electrodes were an electrocorticogram electrode, a mesh intracortical electrode with a unique lattice-like mesh structure to fixate neural tissue, and a guide cannula electrode with recording microelectrodes placed on the curved surface of a guide cannula as a microdialysis probe. In vivo neural recordings using anesthetized rats demonstrated that these electrodes can be used to record neural activities repeatedly without any breakage and mechanical failures, which potentially promises stable recordings for long periods of time. These successes make us believe that this PSPI-based fabrication is a powerful method, permitting flexible design and easy optimization of electrode architectures for a variety of electrophysiological experimental research with improved neural recording performance.

  4. Three-dimensional autonomous pacemaker in the photosensitive Belousov-Zhabotinsky medium

    Science.gov (United States)

    Azhand, A.; Totz, J. F.; Engel, H.

    2014-10-01

    In experiments with the photosensitive Belousov-Zhabotinsky reaction (PBZR) we found a stable three-dimensional organizing center that periodically emits trigger waves of chemical concentration. The experiments are performed in a parameter regime with negative line tension using an open gel reactor to maintain stationary non-equilibrium conditions. The observed periodic wave source is formed by a scroll ring stabilized due to its interaction with a no-flux boundary. Sufficiently far from the boundary, the scroll ring expands and undergoes the negative line tension instability before it finally develops into scroll wave turbulence. Our experimental results are reproduced by numerical integration of the modified Oregonator model for the PBZR. Stationary and breathing self-organized pacemakers have been found in these numerical simulations. In the latter case, both the radius of the scroll ring and the distance of its filament plane to the no-flux boundary after some transient undergo undamped stable limit cycle oscillations. So far, contrary to their stationary counterpart, the numerically predicted breathing autonomous pacemaker has not been observed in the chemical experiment.

  5. The influence of chromatic background on the photosensitivity of tilapia erythrophores

    Directory of Open Access Journals (Sweden)

    Shyh-Chi Chen

    2014-01-01

    Non-mammalian vertebrates and invertebrates use extraretinal photoreceptors to detect light and perform diverse non-image-forming functions. Compared to well-studied visual systems, the effect of ambient light conditions on photosensory systems of extraretinal photoreceptors is poorly understood. Chromatophores are photosensitive dermal pigment cells that play an important role in the formation of body color patterns to fit the surrounding environment. Here, we used tilapia erythrophores to investigate the relationship between environmental light and chromatophore photoresponses. All erythrophores from three spectral conditions aggregated their pigment granules in UV/short wavelengths and dispersed in middle/long wavelengths. Unlike retinal visual systems, environmental light did not change the usage of the primary opsins responsible for aggregation and dispersion. In addition, short wavelength-rich and red-shifted background conditions led to an inhibitory effect on erythrophore photoresponses. We suggest that, as extraretinal photoreceptors for non-image-forming functions, chromatophores directly adjust their photoresponse sensitivity via changes in opsin expression levels rather than opsin types when environmental light changes.

  6. The influence of chromatic background on the photosensitivity of tilapia erythrophores.

    Science.gov (United States)

    Chen, Shyh-Chi; Hornsby, Mark A W; Robertson, R Meldrum; Hawryshyn, Craig W

    2014-02-15

    Non-mammalian vertebrates and invertebrates use extraretinal photoreceptors to detect light and perform diverse non-image-forming functions. Compared to well-studied visual systems, the effect of ambient light conditions on photosensory systems of extraretinal photoreceptors is poorly understood. Chromatophores are photosensitive dermal pigment cells that play an important role in the formation of body color patterns to fit the surrounding environment. Here, we used tilapia erythrophores to investigate the relationship between environmental light and chromatophore photoresponses. All erythrophores from three spectral conditions aggregated their pigment granules in UV/short wavelengths and dispersed in middle/long wavelengths. Unlike retinal visual systems, environmental light did not change the usage of the primary opsins responsible for aggregation and dispersion. In addition, short wavelength-rich and red-shifted background conditions led to an inhibitory effect on erythrophore photoresponses. We suggest that, as extraretinal photoreceptors for non-image-forming functions, chromatophores directly adjust their photoresponse sensitivity via changes in opsin expression levels rather than opsin types when environmental light changes.

  7. Photosensitizer-Conjugated Hyaluronic Acid-Shielded Polydopamine Nanoparticles for Targeted Photomediated Tumor Therapy.

    Science.gov (United States)

    Han, Jieun; Park, Wooram; Park, Sin-Jung; Na, Kun

    2016-03-01

    Photodynamic therapy (PDT) is a widely used clinical option for tumor therapy. However, the clinical utilization of conventional small-molecule photosensitizers (PSs) for PDT has been limited by their low selectivity for disease sites, and undesirable photoactivation. To overcome these limitations, we demonstrated a tumor-specific and photoactivity-controllable nanoparticle photomedicine based on a combination of PS-biomacromolecule conjugates and polydopamine nanoparticles (PD-NP) for an effective tumor therapy. This novel photomedicine consisted of a PD-NP core and a PS-conjugated hyaluronic acid (PS-HA) shell. The PD-NP and the PS-HA play roles as a quencher for PSs and a cancer targeting moiety, respectively. The synthesized PS-HA-shielded PD-NPs (PHPD-NPs) had a relatively narrow size distribution (approximately 130 nm) with uniform spherical shapes. In response to cancer-specific intracellular enzymes (e.g., hyaluronidase), the PHPD-NPs exhibited an excellent singlet oxygen generation capacity for PDT. Furthermore, an efficient photothermal conversion ability for photothermal therapy (PTT) was also shown in the PHPD-NPs system. These properties provide superior therapeutic efficacy against cancer cells. In mice tumor model, the photoactive restorative effects of the PHPD-NPs were much higher in cancer microenvironments compared to that in the normal tissue. As a result, the PHPD-NPs showed a significant antitumor activity in in vivo mice tumor model. The nanoparticle photomedicine design is a novel strategy for effective tumor therapy.

  8. In vitro biological effects of novel type I photosensitizers and their mechanism of action

    Science.gov (United States)

    Karwa, Amolkumar; Rajagopalan, Raghavan; Poreddy, Amruta R.; Sympson, Carolyn; Cantrell, Gary L.; Dorshow, Richard B.

    2010-02-01

    Photodynamic therapy involving Type 2 photosenstizers has been conspicuously successful in the treatment of various lesions. Type 1 process, in contrast has not received much attention despite its considerable potential. We have prepared several classes of molecules containing fragile bonds that will produce reactive intermediates such as radicals and nitrenes upon photoexcitation with UV-A and visible light. In a primary screen, many of these compounds had a significant concentration and light dose dependent effect on the cell viability on U937. The chemistry of these compounds differentiated their ability to induced cytotoxic effects. To further establish these findings, we tested one compound representing each class of chemistry in three different tumor cell lines. Cells were incubated with three different concentrations (100μM, 25μM and 6.25μM) and exposed to UV light dose of 4J/cm2 and 8J/cm2. The compounds showed varying effects on viability in different cell lines. Finally we also investigated the ability to induce apoptosis as the mechanism of cell death in HCT116 cell lines using the experimental conditions mentioned. The type 1 photosensitizers induced apoptosis as early as 4 hours after exposure in HCT116 cells and the rate of apoptosis increased with time with majority of cells in late apoptotic or necrotic stage.

  9. Hydrophobicity, topography in membranes and photosensitization of silicon phthalocyanines with axial ligands of varying lengths.

    Science.gov (United States)

    Sholto, Alan; Ehrenberg, Benjamin

    2008-03-01

    Six amphiphilic silicon phthalocyanines (SiPc's) axially linked to a dimethylated amino alkyl group of varying length have been examined for their potential suitability as photosensitizers for photodynamic therapy (PDT). This group of molecules was chosen because the length of the axial ligand might place the chromophoric part of the molecule at different vertical depths in the membrane and possibly affect the extent of membrane localized damage caused by singlet oxygen. We tested the relative penetration depth of the SiPc groups in the membrane by the extent to which their fluorescence was quenched by external iodide ions. We also measured singlet oxygen quantum yields of the SiPc's in a liposome membrane, using the fluorescent target for singlet oxygen, 9,10-dimethylanthracene. The hydrophobicity parameters, LogP, were calculated and were also measured. Some correlation was found between them and Kb's, the binding constants for liposomes. The effect of the axial ligand's length is less striking than in similar cases with hematoporphyrins and protoporphyrins. We link this smaller effect with a bending of the linker chain that enables, sterically, a better positioning of the sensitizer molecules within the ordered lipid layer structure.

  10. The bulk photovoltaic effect as a platform for ultrafast, nanoscale photosensitive devices

    Science.gov (United States)

    Young, Steve

    2017-05-01

    The bulk photovoltaic effect refers to the generation of photocurrents and photovoltages in bulk single-phase materials. It requires only that the material possess broken inversion symmetry, and occurs due a unique mechanism known as "shift current." Discovered over a half-century ago, it received little attention decades due to extremely poor observed efficiency. However, in recent years, it has been both theoretically and experimentally investigated in a variety of new systems and materials, and significant improvements in performance have been achieved. In this talk, I will provide a brief overview of the physics of the bulk photovoltaic effect and survey the experimental and theoretical advances that have been made in its understanding and optimization. I will cover in detail the unique properties of the bulk photovoltaic effect that distinguish it from conventional photovoltaic effects, including photovoltages substantially exceeding the material's band gap, response amplitudes and directions that can depend on both photon energy and polarization, and response that occurs on ultrafast timescales. Finally, I will explore the potential for these features to enable novel and improved photosensitive devices, especially in combination with other functional materials.

  11. Cationic porphyrin derivatives for application in photodynamic therapy of cancer

    Science.gov (United States)

    Prack McCormick, Bárbara P.; Florencia Pansa, M.; Milla Sanabria, Laura N.; Carvalho, Carla M. B.; Faustino, M. Amparo F.; Neves, Maria Graça P. M. S.; Cavaleiro, José A. S.; Rumie Vittar, Natalia B.; Rivarola, Viviana A.

    2014-04-01

    Current studies in photodynamic therapy (PDT) against cancer are focused on the development of new photosensitizers (PSs), with higher phototoxic action. The aim of this study was to compare the therapeutic efficiency of tri-cationic meso-substituted porphyrin derivatives (Tri-Py+-Me-PF, Tri-Py+-Me-Ph, Tri-Py+-Me-CO2Me and Tri-Py+-Me-CO2H) with the well-known tetra-cationic T4PM. The phototoxic action of these derivatives was assessed in human colon adenocarcinoma cells by cell viability, intracellular localization and nuclear morphology analysis. In the experimental conditions used we determined that after light activation -PF, -Ph and -CO2Me cause a more significant decline of cell viability compared to -CO2H and T4PM. These results suggest that the nature of the peripheral substituent influences the extent of cell photodamage. Moreover, we have demonstrated that PS concentration, physicochemical properties and further light activation determine the PDT response. All porphyrins were clearly localized as a punctuated pattern in the cytoplasm of the cells, and the PDT scheme resulted in apoptotic cell death after 3 h post-PDT. The tri-cationic porphyrin derivatives Tri-Py+-Me-PF, Tri-Py+-Me-Ph and Tri-Py+-Me-CO2Me showed a promising ability, making them good photosensitizer candidates for oncological PDT.

  12. The synthesis, photophysical and photobiological properties and in vitro structure-activity relationships of a set of silicon phthalocyanine PDT photosensitizers.

    Science.gov (United States)

    He, J; Larkin, H E; Li, Y S; Rihter, D; Zaidi, S I; Rodgers, M A; Mukhtar, H; Kenney, M E; Oleinick, N L

    1997-03-01

    Four silicon phthalocyanine photosensitizers have been prepared and studied in an effort to learn more about the structural features that a silicon phthalocyanine must have in order to be a good photodynamic therapy (PDT) photosensitizer. The compounds that have been studied are the known phthalocyanines HOSiPcOSi(CH3)2-(CH2)3N(CH3)2, Pc 4; and SiPc[OSi(CH3)2(CH2)3N(CH3)2]2, Pc 12; and the new photosensitizers HOSiPcOSi(CH3)2- (CH2)3N(CH2CH3)(CH2)2N(CH3)2, Pc 10; and SiPc[OSi (CH3)2(CH2)3N(CH2CH3)(CH2)2N(CH3)2]2, Pc 18. The triplet lifetimes of the four photosensitizers, their singlet oxygen quantum yields, their ability to photoenhance the generation of lipid peroxidation products in human erythrocyte ghosts, their ability to partition into V79 cells and their ability to photokill V79 and L5178Y-R cells have been determined. It is concluded that the presence of a small axial ligand (e.g. an OH ligand) is not necessary for efficient photosensitization, the presence of two aminosiloxy ligands generally provides at least as good photosensitization as one such ligand, and the presence of an elongated diaminosiloxy axial ligand rather than a short aminosiloxy ligand is less desirable. Further, it is concluded that the presence of structural features leading to improvement in the association between the photosensitizers and important cellular targets are more useful than those leading to improvements in their already acceptable photophysical and photochemical properties.

  13. Could nitrile derivatives of turnip (Brassica rapa) glucosinolates be hepato- or cholangiotoxic in cattle?

    Science.gov (United States)

    Collett, Mark G; Stegelmeier, Bryan L; Tapper, Brian A

    2014-07-30

    Turnip (Brassica rapa ssp. rapa) and rape (Brassica napus ssp. biennis) and other brassica forage crops are regarded as "safe" feed for cattle during late summer and fall in the North Island of New Zealand when high Pithomyces chartarum spore counts in pastures frequently lead to sporidesmin toxicity (facial eczema). Sporadic acute severe cases of turnip photosensitization in dairy cows characteristically exhibit high γ-glutamyl transferase and glutamate dehydrogenase serum enzyme activities that mimic those seen in facial eczema. The two diseases can, however, be distinguished by histopathology of the liver, where lesions, in particular those affecting small bile ducts, differ. To date, the hepato-/cholangiotoxic phytochemical causing liver damage in turnip photosensitization in cattle is unknown. Of the hydrolysis products of the various glucosinolate secondary compounds found in high concentrations in turnip and rape, work has shown that nitriles and epithionitriles can be hepatotoxic (and nephro- or pancreatotoxic) in rats. These derivatives include β-hydroxy-thiiranepropanenitrile and 3-hydroxy-4-pentenenitrile from progoitrin; thiiranepropanenitrile and 4-pentenenitrile from gluconapin; thiiranebutanenitrile and 5-hexenenitrile from glucobrassicanapin; phenyl-3-propanenitrile from gluconasturtiin; and indole-3-acetonitrile from glucobrassicin. This perspective explores the possibility of the preferential formation of such derivatives, especially the epithionitriles, in acidic conditions in the bovine rumen, followed by absorption, hepatotoxicity, and secondary photosensitization.

  14. Financial Derivatives

    DEFF Research Database (Denmark)

    Wigan, Duncan

    2013-01-01

    Contemporary derivatives mark the development of capital and constitute a novel form of ownership. By reconfiguring the temporal, spatial and legal character of ownership derivatives present a substantive challenge to the tax collecting state. While fiscal systems are nationally bounded and inheren...... and inherently static, capital itself is unprecedentedly mobile, fluid and fungible. As such derivatives raise the specter of ‘financial weapons of mass destruction’....

  15. Mice deficient of glutamatergic signaling from intrinsically photosensitive retinal ganglion cells exhibit abnormal circadian photoentrainment.

    Science.gov (United States)

    Purrier, Nicole; Engeland, William C; Kofuji, Paulo

    2014-01-01

    Several aspects of behavior and physiology, such as sleep and wakefulness, blood pressure, body temperature, and hormone secretion exhibit daily oscillations known as circadian rhythms. These circadian rhythms are orchestrated by an intrinsic biological clock in the suprachiasmatic nuclei (SCN) of the hypothalamus which is adjusted to the daily environmental cycles of day and night by the process of photoentrainment. In mammals, the neuronal signal for photoentrainment arises from a small subset of intrinsically photosensitive retinal ganglion cells (ipRGCs) that send a direct projection to the SCN. ipRGCs also mediate other non-image-forming (NIF) visual responses such as negative masking of locomotor activity by light, and the pupillary light reflex (PLR) via co-release of neurotransmitters glutamate and pituitary adenylate cyclase-activating peptide (PACAP) from their synaptic terminals. The relative contribution of each neurotransmitter system for the circadian photoentrainment and other NIF visual responses is still unresolved. We investigated the role of glutamatergic neurotransmission for circadian photoentrainment and NIF behaviors by selective ablation of ipRGC glutamatergic synaptic transmission in mice. Mutant mice displayed delayed re-entrainment to a 6 h phase shift (advance or delay) in the light cycle and incomplete photoentrainment in a symmetrical skeleton photoperiod regimen (1 h light pulses between 11 h dark periods). Circadian rhythmicity in constant darkness also was reduced in some mutant mice. Other NIF responses such as the PLR and negative masking responses to light were also partially attenuated. Overall, these results suggest that glutamate from ipRGCs drives circadian photoentrainment and negative masking responses to light.

  16. Central projections of intrinsically photosensitive retinal ganglion cells in the macaque monkey

    Science.gov (United States)

    Hannibal, J.; Kankipati, L.; Strang, C.E.; Peterson, B.B.; Dacey, D.; Gamlin, P.D.

    2014-01-01

    Circadian rhythms generated by the suprachiasmatic nucleus (SCN) are entrained to the environmental light/dark cycle via intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin and the neuropeptide PACAP. The ipRGCs regulate other non-image-forming visual functions such as the pupillary light reflex, masking behaviour and light induced melatonin suppression. To evaluate whether PACAP immunoreactive retinal projections are useful as a marker for central projection of ipRGCs in the monkey brain, we characterized the occurrence of PACAP in melanopsin expressing ipRGCs and in the retinal target areas in the brain visualized by the anterograde tracer Cholera Toxin subunit B (CtB) in combination with PACAP staining. In the retina, PACAP and melanopsin were found to be co-stored in 99% of melanopsin expressing cells characterized as inner and outer stratifying melanopsin RGCs. Two macaque monkeys were anesthetized and received a unilateral intravitreal injection of CtB. Bilateral retinal projections containing co-localized CtB and PACAP immunostaining were identified in the SCN, the lateral geniculate complex (LGN) including the pregeniculate nucleus (PrGC), the pretectal olivary nucleus (PON), the nucleus of the optic tract (NOT), the brachium of the superior colliculus (BSC), and the superior colliculus (SC). In conclusion, PACAP immunoreactive projections with co-localized CtB represent retinal projections of ipRGCs in the macaque monkey, and support previous retrograde tracer studies demonstrating that melanopsin containing retinal projections reach areas in the primate brain involved in both image and non-image-forming visual processing. PMID:24752373

  17. Photosensitizer and peptide-conjugated PAMAM dendrimer for targeted in vivo photodynamic therapy

    Directory of Open Access Journals (Sweden)

    Narsireddy A

    2015-11-01

    Full Text Available Amreddy Narsireddy,1 Kurra Vijayashree,2 Mahesh G Adimoolam,1 Sunkara V Manorama,1 Nalam M Rao21CSIR – Indian Institute of Chemical Technology, 2CSIR – Centre for Cellular and Molecular Biology, Hyderabad, IndiaAbstract: Challenges in photodynamic therapy (PDT include development of efficient near infrared-sensitive photosensitizers (5,10,15,20-tetrakis(4-hydroxyphenyl-21H,23H-porphine [PS] and targeted delivery of PS to the tumor tissue. In this study, a dual functional dendrimer was synthesized for targeted PDT. For targeting, a poly(amidoamine dendrimer (G4 was conjugated with a PS and a nitrilotriacetic acid (NTA group. A peptide specific to human epidermal growth factor 2 was expressed in Escherichia coli with a His-tag and was specifically bound to the NTA group on the dendrimer. Reaction conditions were optimized to result in dendrimers with PS and the NTA at a fractional occupancy of 50% and 15%, respectively. The dendrimers were characterized by nuclear magnetic resonance, matrix-assisted laser desorption/ionization, absorbance, and fluorescence spectroscopy. Using PS fluorescence, cell uptake of these particles was confirmed by confocal microscopy and fluorescence-activated cell sorting. PS-dendrimers are more efficient than free PS in PDT-mediated cell death assays in HER2 positive cells, SK-OV-3. Similar effects were absent in HER2 negative cell line, MCF-7. Compared to free PS, the PS-dendrimers have shown significant tumor suppression in a xenograft animal tumor model. Conjugation of a PS with dendrimers and with a targeting agent has enhanced photodynamic therapeutic effects of the PS.Keywords: photodynamic therapy, dendrimers, nanoparticle, targeted delivery, Affibody, xenograft animal model

  18. Effects of Medicinal Plant Extracts and Photosensitization on Aflatoxin Producing Aspergillus flavus (Raper and Fennell

    Directory of Open Access Journals (Sweden)

    Loise M. Njoki

    2017-01-01

    Full Text Available This study was undertaken with an aim of exploring the effectiveness of medicinal plant extracts in the control of aflatoxin production. Antifungal properties, photosensitization, and phytochemical composition of aqueous and organic extracts of fruits from Solanum aculeastrum, bark from Syzygium cordatum, and leaves from Prunus africana, Ocimum lamiifolium, Lippia kituiensis, and Spinacia oleracea were tested. Spores from four-day-old cultures of previously identified toxigenic fungi, UONV017 and UONV003, were used. Disc diffusion and broth dilution methods were used to test the antifungal activity. The spores were suspended in 2 ml of each extract separately and treated with visible light (420 nm for varying periods. Organic extracts displayed species and concentration dependent antifungal activity. Solanum aculeastrum had the highest zones of inhibition diameters in both strains: UONV017 (mean = 18.50±0.71 mm and UONV003 (mean = 11.92±0.94 mm at 600 mg/ml. Aqueous extracts had no antifungal activity because all diameters were below 8 mm. Solanum aculeastrum had the lowest minimum inhibitory concentration at 25 mg/ml against A. flavus UONV017. All the plant extracts in combination with light reduced the viability of fungal conidia compared with the controls without light, without extracts, and without both extracts and light. Six bioactive compounds were analyzed in the plant extracts. Medicinal plant extracts in this study can control conidia viability and hence with further development can control toxigenic fungal spread.

  19. Susceptibility of Candida albicans and Candida dubliniensis to Photodynamic Therapy Using Four Dyes as the Photosensitizer

    Science.gov (United States)

    Hosseini, Nasim; Yazdanpanah, Samira; Saki, Maryam; Rezazadeh, Fahimeh; Ghapanchi, Janan; Zomorodian, Kamiar

    2016-01-01

    Statement of the Problem: Oral candidiasis is the most common opportunistic infection affecting the human oral cavity. Photodynamic therapy, as one of its proposed treatment modalities, needs a distinct dye for achieving the best effect. Purpose: The purpose of this study was to evaluate photosensitization effects of four distinct dyes on standard suspension of Candida albicans (C. albicans) and Candida dubliniensis (C. dubliniensis) and biofilm of C. albicans considering the obtained optimum dye concentration and duration of laser irradiation. Materials and Method: In this in vitro study, colony forming units (CFU) of two sets of four groups of Laser plus Dye (L+D+), Dye (L-D+), Laser (L+D-) and No Laser, No Dye (L-D-) were assessed individually with different methylene blue concentrations and laser irradiation period. The photodynamic therapy effect on standard suspension of Candida species (using methylene blue, aniline blue, malachite green and crystal violet) were studied based on the obtained results. Similar investigation was performed on biofilm of C. albicans using the spectral absorbance. Data were imported to SPSS and assessed by statistical tests of analysis of variance (ANOVA) and Tukey test (α= 0.05). Results: CFU among the different dye concentration and irradiation time decrease in dose- and time-dependent manner (p> 0.05), all of which were significantly lower than the control groups (p 0.05) though all of them were significantly decrease CFU compared with the control groups (p< 0.05). In L+D- and L+D+ groups, biofilm was significantly destroyed more than that of L-D- (p< 0.05). Conclusion: Photodynamic therapy might be used as an effective procedure to treat Candida associated mucocutaneous diseases and killing biofilm in the infected surfaces such as dentures. PMID:27942552

  20. A five-primary photostimulator suitable for studying intrinsically photosensitive retinal ganglion cell functions in humans.

    Science.gov (United States)

    Cao, Dingcai; Nicandro, Nathaniel; Barrionuevo, Pablo A

    2015-01-26

    Intrinsically photosensitive retinal ganglion cells (ipRGCs) can respond to light directly through self-contained photopigment, melanopsin. IpRGCs also receive synaptic inputs from rods and cones. Thus, studying ipRGC functions requires a novel photostimulating method that can account for all of the photoreceptor inputs. Here, we introduced an inexpensive LED-based five-primary photostimulator that can control the excitations of rods, S-, M-, L-cones, and melanopsin-containing ipRGCs in humans at constant background photoreceptor excitation levels, a critical requirement for studying the adaptation behavior of ipRGCs with rod, cone, or melanopsin input. We described the theory and technical aspects (including optics, electronics, software, and calibration) of the five-primary photostimulator. Then we presented two preliminary studies using the photostimulator we have implemented to measure melanopsin-mediated pupil responses and temporal contrast sensitivity function (TCSF). The results showed that the S-cone input to pupil responses was antagonistic to the L-, M- or melanopsin inputs, consistent with an S-OFF and (L + M)-ON response property of primate ipRGCs (Dacey et al., 2005). In addition, the melanopsin-mediated TCSF had a distinctive pattern compared with L + M or S-cone mediated TCSF. Other than controlling individual photoreceptor excitation independently, the five-primary photostimulator has the flexibility in presenting stimuli modulating any combination of photoreceptor excitations, which allows researchers to study the mechanisms by which ipRGCs combine various photoreceptor inputs. © 2015 ARVO.

  1. The role of intrinsically photosensitive retinal ganglion cells in nonimage-forming responses to light

    Directory of Open Access Journals (Sweden)

    Warthen DM

    2012-09-01

    Full Text Available Daniel M Warthen,1,2 Ignacio Provencio11Department of Biology, University of Virginia, Charlottesville, VA, USA; 2Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USAAbstract: Light exerts many effects on behavior and physiology. These effects can be characterized as either image-forming or nonimage-forming (NIF visual processes. Image-forming vision refers to the process of detecting objects and organisms in the environment and distinguishing their physical characteristics, such as size, shape, and direction of motion. NIF vision, in contrast, refers to effects of light that are independent of fine spatiotemporal vision. NIF effects are many and varied, ranging from modulation of basal physiology, such as heart rate and body temperature, to changes in higher functions, such as mood and cognitive performance. In mammals, many NIF effects of light are dependent upon the inner retinal photopigment melanopsin and the cells in which melanopsin is expressed, the intrinsically photosensitive retinal ganglion cells (ipRGCs. The ipRGCs project broadly throughout the brain. Many of these projections terminate in areas known to mediate NIF effects, while others terminate in regions whose link to photoreception remains to be established. Additionally, the presence of ipRGC projections to areas of the brain with no known link to photoreception suggests the existence of additional ipRGC-mediated NIF effects. This review summarizes the known NIF effects of light and the role of melanopsin and ipRGCs in driving these effects, with an eye toward stimulating further investigation of the many and varied effects of light on physiology and behavior.Keywords: amygdala, bed nucleus of the stria terminalis, melanopsin, opsin, optic nerve, retina

  2. Mice deficient of glutamatergic signaling from intrinsically photosensitive retinal ganglion cells exhibit abnormal circadian photoentrainment.

    Directory of Open Access Journals (Sweden)

    Nicole Purrier

    Full Text Available Several aspects of behavior and physiology, such as sleep and wakefulness, blood pressure, body temperature, and hormone secretion exhibit daily oscillations known as circadian rhythms. These circadian rhythms are orchestrated by an intrinsic biological clock in the suprachiasmatic nuclei (SCN of the hypothalamus which is adjusted to the daily environmental cycles of day and night by the process of photoentrainment. In mammals, the neuronal signal for photoentrainment arises from a small subset of intrinsically photosensitive retinal ganglion cells (ipRGCs that send a direct projection to the SCN. ipRGCs also mediate other non-image-forming (NIF visual responses such as negative masking of locomotor activity by light, and the pupillary light reflex (PLR via co-release of neurotransmitters glutamate and pituitary adenylate cyclase-activating peptide (PACAP from their synaptic terminals. The relative contribution of each neurotransmitter system for the circadian photoentrainment and other NIF visual responses is still unresolved. We investigated the role of glutamatergic neurotransmission for circadian photoentrainment and NIF behaviors by selective ablation of ipRGC glutamatergic synaptic transmission in mice. Mutant mice displayed delayed re-entrainment to a 6 h phase shift (advance or delay in the light cycle and incomplete photoentrainment in a symmetrical skeleton photoperiod regimen (1 h light pulses between 11 h dark periods. Circadian rhythmicity in constant darkness also was reduced in some mutant mice. Other NIF responses such as the PLR and negative masking responses to light were also partially attenuated. Overall, these results suggest that glutamate from ipRGCs drives circadian photoentrainment and negative masking responses to light.

  3. Central projections of intrinsically photosensitive retinal ganglion cells in the macaque monkey.

    Science.gov (United States)

    Hannibal, J; Kankipati, L; Strang, C E; Peterson, B B; Dacey, D; Gamlin, P D

    2014-07-01

    Circadian rhythms generated by the suprachiasmatic nucleus (SCN) are entrained to the environmental light/dark cycle via intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin and the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP). The ipRGCs regulate other nonimage-forming visual functions such as the pupillary light reflex, masking behavior, and light-induced melatonin suppression. To evaluate whether PACAP-immunoreactive retinal projections are useful as a marker for central projection of ipRGCs in the monkey brain, we characterized the occurrence of PACAP in melanopsin-expressing ipRGCs and in the retinal target areas in the brain visualized by the anterograde tracer cholera toxin subunit B (CtB) in combination with PACAP staining. In the retina, PACAP and melanopsin were found to be costored in 99% of melanopsin-expressing cells characterized as inner and outer stratifying melanopsin RGCs. Two macaque monkeys were anesthetized and received a unilateral intravitreal injection of CtB. Bilateral retinal projections containing colocalized CtB and PACAP immunostaining were identified in the SCN, the lateral geniculate complex including the pregeniculate nucleus, the pretectal olivary nucleus, the nucleus of the optic tract, the brachium of the superior colliculus, and the superior colliculus. In conclusion, PACAP-immunoreactive projections with colocalized CtB represent retinal projections of ipRGCs in the macaque monkey, supporting previous retrograde tracer studies demonstrating that melanopsin-containing retinal projections reach areas in the primate brain involved in both image- and nonimage-forming visual processing.

  4. Early photosensitizer uptake kinetics predict optimum drug-light interval for photodynamic therapy

    Science.gov (United States)

    Sinha, Lagnojita; Elliott, Jonathan T.; Hasan, Tayyaba; Pogue, Brian W.; Samkoe, Kimberley S.; Tichauer, Kenneth M.

    2015-03-01

    Photodynamic therapy (PDT) has shown promising results in targeted treatment of cancerous cells by developing localized toxicity with the help of light induced generation of reactive molecular species. The efficiency of this therapy depends on the product of the intensity of light dose and the concentration of photosensitizer (PS) in the region of interest (ROI). On account of this, the dynamic and variable nature of PS delivery and retention depends on many physiological factors that are known to be heterogeneous within and amongst tumors (e.g., blood flow, blood volume, vascular permeability, and lymph drainage rate). This presents a major challenge with respect to how the optimal time and interval of light delivery is chosen, which ideally would be when the concentration of PS molecule is at its maximum in the ROI. In this paper, a predictive algorithm is developed that takes into consideration the variability and dynamic nature of PS distribution in the body on a region-by-region basis and provides an estimate of the optimum time when the PS concentration will be maximum in the ROI. The advantage of the algorithm lies in the fact that it predicts the time in advance as it takes only a sample of initial data points (~12 min) as input. The optimum time calculated using the algorithm estimated a maximum dose that was only 0.58 +/- 1.92% under the true maximum dose compared to a mean dose error of 39.85 +/- 6.45% if a 1 h optimal light deliver time was assumed for patients with different efflux rate constants of the PS, assuming they have the same plasma function. Therefore, if the uptake values of PS for the blood and the ROI is known for only first 12 minutes, the entire curve along with the optimum time of light radiation can be predicted with the help of this algorithm.

  5. Photo-sensitive Ge nanocrystal based films controlled by substrate deposition temperature

    KAUST Repository

    Stavarache, Ionel

    2017-07-21

    Lowering the temperature of crystallization by deposition of thin films on a heated substrate represents the easiest way to find new means to develop and improve new working devices based on nanocrystals embedded in thin films. The improvements are strongly related with the increasing of operation speed, substantially decreasing the energy consumption and reducing unit fabrication costs of the respective semiconductor devices. This approach avoids major problems, such as those related to diffusion or difficulties in controlling of nanocrystallites size, which appear during thermal treatments at high temperatures after deposition. It is reported here the significant progress introduced by synthesis procedure to the in-situ structuring of Ge nanocrystallites in SiO2 thin films by heating the substrate at low temperature, 400 °C during co-deposition of Ge and SiO2 by magnetron sputtering. As a proof-of-concept, a Si/Ge-NCs:SiO2 photo-sensitive structure was fabricated thereof and characterized. The structure shows superior performance on broad operation bandwidth from visible to near-infrared, as strong rectification properties in dark, significant current rise in the inversion mode when illuminated, high responsivity, high photo-detectivity of 1014 Jones, quick response and significant conversion efficiency of 850 %. This simple preparation approach brings an important contribution to the efort of structuring Ge nanocrystallites in SiO2 thin films at a lower temperature for the purpose of using these materials for devices in optoelectronics, solar cells and electronics on flexible substrates.

  6. Sunlight exposure behaviour and vitamin D status in photosensitive patients: longitudinal comparative study with healthy individuals at U.K. latitude.

    Science.gov (United States)

    Rhodes, L E; Webb, A R; Berry, J L; Felton, S J; Marjanovic, E J; Wilkinson, J D; Vail, A; Kift, R

    2014-12-01

    Low vitamin D status is prevalent in wintertime in populations at northerly latitudes. Photosensitive patients are advised to practise sun avoidance, but their sunlight exposure levels, photoprotective measures and resulting vitamin D status are unknown. To examine seasonal vitamin D status in photosensitive patients relative to healthy individuals and to assess quantitatively behavioural and demographic contributors. This was a longitudinal prospective cohort study (53·5°N) examining year-round 25-hydroxyvitamin D [25(OH)D] levels, sun-exposure behaviour and oral vitamin D intake in photosensitive patients diagnosed at a photoinvestigation unit (n = 53), compared with concurrently assessed healthy adults (n = 109). Photosensitive patients achieved seasonal 25(OH)D variation, but insufficient (exposure (P = 0·004) and greater sunscreen use (P exposure predicted summer peak and winter trough 25(OH)D levels. A 1 μg per day increment in supplementary vitamin D raised summer and winter 25(OH)D by 5% (95% CI 3-7) and 9% (95% CI 5-12), respectively (both P < 0·001). Photosensitive patients are, through their photoprotective measures, at high risk of year-round low vitamin D status. Guidance on oral measures should target this patient group and their physicians. © 2014 British Association of Dermatologists.

  7. UV-emitting upconversion-based TiO2 photosensitizing nanoplatform: near-infrared light mediated in vivo photodynamic therapy via mitochondria-involved apoptosis pathway.

    Science.gov (United States)

    Hou, Zhiyao; Zhang, Yuanxin; Deng, Kerong; Chen, Yinyin; Li, Xuejiao; Deng, Xiaoran; Cheng, Ziyong; Lian, Hongzhou; Li, Chunxia; Lin, Jun

    2015-03-24

    Photodynamic therapy (PDT) is a promising antitumor treatment that is based on the photosensitizers that inhibit cancer cells by yielding reactive oxygen species (ROS) after irradiation of light with specific wavelengths. As a potential photosensitizer, titanium dioxide (TiO2) exhibits minimal dark cytotoxicity and excellent ultraviolet (UV) light triggered cytotoxicity, but is challenged by the limited tissue penetration of UV light. Herein, a novel near-infrared (NIR) light activated photosensitizer for PDT based on TiO2-coated upconversion nanoparticle (UCNP) core/shell nanocomposites (UCNPs@TiO2 NCs) is designed. NaYF4:Yb(3+),Tm(3+)@NaGdF4:Yb(3+) core/shell UCNPs can efficiently convert NIR light to UV emission that matches well with the absorption of TiO2 shells. The UCNPs@TiO2 NCs endocytosed by cancer cells are able to generate intracellular ROS under NIR irradiation, decreasing the mitochondrial membrane potential to release cytochrome c into the cytosol and then activating caspase 3 to induce cancer cell apoptosis. NIR light triggered PDT of tumor-bearing mice with UCNPs@TiO2 as photosensitizers can suppress tumor growth efficiently due to the better tissue penetration than UV irradiation. On the basis of the evidence of in vitro and in vivo results, UCNPs@TiO2 NCs could serve as an effective photosensitizer for NIR light mediated PDT in antitumor therapy.

  8. Financial Derivatives

    DEFF Research Database (Denmark)

    Wigan, Duncan

    2013-01-01

    Contemporary derivatives mark the development of capital and constitute a novel form of ownership. By reconfiguring the temporal, spatial and legal character of ownership derivatives present a substantive challenge to the tax collecting state. While fiscal systems are nationally bounded...

  9. Comparison of Riboflavin and Toluidine Blue O as Photosensitizers for Photoactivated Disinfection on Endodontic and Periodontal Pathogens In Vitro.

    Directory of Open Access Journals (Sweden)

    Henrik Krarup Nielsen

    Full Text Available Photoactivated disinfection has a strong local antimicrobial effect. In the field of dentistry it is an emerging adjunct to mechanical debridement during endodontic and periodontal treatment. In the present study, we investigate the effect of photoactivated disinfection using riboflavin as a photosensitizer and blue LED light for activation, and compare it to photoactivated disinfection with the widely used combination of toluidine blue O and red light. Riboflavin is highly biocompatible and can be activated with LED lamps at hand in the dental office. To date, no reports are available on the antimicrobial effect of photoactivated disinfection using riboflavin/blue light on oral microorganisms. Planktonic cultures of eight organisms frequently isolated from periodontal and/or endodontic lesions (Aggregatibacter actinomycetemcomitans, Candida albicans, Enterococcus faecalis, Escherischia coli, Lactobacillus paracasei, Porphyromonas gingivalis, Prevotella intermedia and Propionibacterium acnes were subjected to photoactivated disinfection with riboflavin/blue light and toluidine blue O/red light, and survival rates were determined by CFU counts. Within the limited irradiation time of one minute, photoactivated disinfection with riboflavin/blue light only resulted in minor reductions in CFU counts, whereas full kills were achieved for all organisms when using toluidine blue O/red light. The black pigmented anaerobes P. gingivalis and P. intermedia were eradicated completely by riboflavin/blue light, but also by blue light treatment alone, suggesting that endogenous chromophores acted as photosensitizers in these bacteria. On the basis of our results, riboflavin cannot be recommended as a photosensitizer used for photoactivated disinfection of periodontal or endodontic infections.

  10. Photodynamic effects on T-cells and skin lesions of a patient with mycosis fungoides using porphyrin photosensitizers

    Science.gov (United States)

    Koenig, Karsten; Boehncke, Wolf-Henning; Rueck, Angelika C.; Kaufmann, Roland; Steiner, Rudolf W.; Sterry, Wolfram

    1994-02-01

    PUVA is a well established phototreatment modality for various dermatoses, like T cell lymphomas, using long-wavelength UV radiation. In contrast, PDT bases on the combination of photosensitizers, especially porphyrins, and radiation mainly in the red spectral region. We analyzed the photochemical effects of both treatments on cell lines MyLa and HuT78, established from patients with cutaneous T cell lymphomas. Our observations document the capability of PDT to inhibit proliferation of transformed T cells similar to PUVA thus pointing out its potential in the treatment of cutaneous T cell lymphomas.

  11. Three-dimensionally embedded indium tin oxide (ITO) films in photosensitive glass: a transparent and conductive platform for microdevices

    Energy Technology Data Exchange (ETDEWEB)

    Beke, S.; Sugioka, K.; Midorikawa, K. [RIKEN - Advanced Science Institute, Laser Technology Laboratory, Saitama (Japan); Koroesi, L.; Dekany, I. [University of Szeged, Supramolecular and Nanostructured Materials Research Group of the Hungarian Academy of Sciences, Szeged (Hungary)

    2011-02-15

    A new method for embedding transparent and conductive two- and three-dimensional microstructures in glass is presented. We show that the internal surface of hollow structures fabricated by femtosecond-laser direct writing inside the photosensitive glass can be coated by indium tin oxide (Sn-doped In{sub 2}O{sub 3}, ITO) using a sol-gel process. The idea of combining two transparent materials with different electrical properties, i.e., insulating and conductive, is very promising and hence it opens new prospects in manufacturing cutting edge microdevices, such as lab-on-a-chips (LOCs) and microelectromechanical systems (MEMS). (orig.)

  12. New photosensitizer with phenylenebisthiophene central unit and cyanovinylene 4-nitrophenyl terminal units for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Mikroyannidis, J.A., E-mail: mikroyan@chemistry.upatras.gr [Chemical Technology Laboratory, Department of Chemistry, University of Patras, GR-26500 Patras (Greece); Suresh, P. [Physics Department, Molecular Electronic and Optoelectronic Device Laboratory, JNV University, Jodhpur (Raj.) 342005 (India); Roy, M.S. [Defence Laboratory, Jodhpur (Raj.) 342011 (India); Sharma, G.D., E-mail: sharmagd_in@yahoo.com [Physics Department, Molecular Electronic and Optoelectronic Device Laboratory, JNV University, Jodhpur (Raj.) 342005 (India); R and D Centre for Engineering and Science, Jaipur Engineering College, Kukas, Jaipur (Raj.) (India)

    2011-06-30

    Graphical abstract: A novel dye D was synthesized and used as photosensitizer for quasi solid state dye-sensitized solar cells. A power conversion efficiency of 4.4% was obtained which was improved to 5.52% when diphenylphosphinic acid (DPPA) was added as coadsorbent. Display Omitted Highlights: > A new low band gap photosensitizer with cyanovinylene 4-nitrophenyl terminal units was synthesized. > A power conversion efficiency of 4.4% was obtained for the dye-sensitized solar cell based on this photosensitizer. > The power conversion efficiency of the dye-sensitized solar cell was further improved to 5.52% when diphenylphosphinic acid was added as coadsorbent. - Abstract: A new low band gap photosensitizer, D, which contains 2,2'-(1,4-phenylene) bisthiophene central unit and cyanovinylene 4-nitrophenyl terminal units at both sides was synthesized. The two carboxyls attached to the 2,5-positions of the phenylene ring act as anchoring groups. Dye D was soluble in common organic solvents, showed long-wavelength absorption maximum at 620-636 nm and optical band gap of 1.72 eV. The electrochemical parameters, i.e. the highest occupied molecular orbital (HOMO) (-5.1 eV) and the lowest unoccupied molecular orbital (LUMO) (-3.3 eV) energy levels of D show that this dye is suitable as molecular sensitizer. The quasi solid state dye-sensitized solar cell (DSSC) based on D shows a short circuit current (J{sub sc}) of 9.95 mA/cm{sup 2}, an open circuit voltage (V{sub oc}) of 0.70 V, and a fill factor (FF) of 0.64 corresponding to an overall power conversion efficiency (PCE) of 4.40% under 100 mW/cm{sup 2} irradiation. The overall PCE has been further improved to 5.52% when diphenylphosphinic acid (DPPA) coadsorbent is incorporated into the D solution. This increased PCE has been attributed to the enhancement in the electron lifetime and reduced recombination of injected electrons with the iodide ions present in the electrolyte with the use of DPPA as coadsorbant. The

  13. The photosensitive effect of Ce on the precipitation of Ag nanoparticles induced by femtosecond laser in silicate glass

    Institute of Scientific and Technical Information of China (English)

    Dai Ye; Qiu Jian-Rong

    2009-01-01

    This paper studies the photosensitive effect of cerium oxide on the precipitation of Ag nanoparticles after femtosecond laser irradiating into silicate glass and successive annealing. Spectroscopy analysis and diffraction efficiency measurements show that the introduction of cerium oxide may increase the concentration of Ag atoms in the femtosecond laser-irradiated regions resulting from the photoreduction reaction Ce3+ + Ag+→ Ce4+ + Ag0 via multiphoton excitation. These results promote the aggregation of Ag nanoparticles during the annealing process. It is also found that different concentrations of cerium oxide may influence the Ag nanoparticle precipitation in the corresponding glass.

  14. Photosensitizer-doped conjugated polymer nanoparticles with high cross-sections for one- and two-photon excitation.

    Science.gov (United States)

    Grimland, Jennifer L; Wu, Changfeng; Ramoutar, Ria R; Brumaghim, Julia L; McNeill, Jason

    2011-04-01

    We report a novel nanoparticle that is promising for photodynamic therapy applications, which consists of a π-conjugated polymer doped with a singlet oxygen photosensitizer. The nanoparticles exhibit highly efficient collection of excitation light due to the large excitation cross-section of the polymer. A quantum efficiency of singlet oxygen production of 0.5 was determined. Extraordinarily large two-photon excitation cross-sections were determined, indicating promise for near infrared multiphoton photodynamic therapy. Gel electrophoresis of DNA after near-UV irradiation in the presence of nanoparticles indicated both purine base and backbone DNA damage.

  15. Thin films and assemblies of photosensitive membrane proteins and colloidal nanocrystals for engineering of hybrid materials with advanced properties.

    Science.gov (United States)

    Zaitsev, Sergei Yu; Solovyeva, Daria O; Nabiev, Igor

    2012-11-15

    The development and study of nano-bio hybrid materials engineered from membrane proteins (the key functional elements of various biomembranes) and nanoheterostructures (inorganic colloidal nanoparticles, transparent electrodes, and films) is a rapidly growing field at the interface of materials and life sciences. The mainspring of the development of bioinspired materials and devices is the fact that biological evolution has solved many problems similar to those that humans are attempting to solve in the field of light-harvesting and energy-transferring inorganic compounds. Along this way, bioelectronics and biophotonics have shown considerable promise. A number of proteins have been explored in terms of bioelectronic device applications, but bacteriorhodopsin (bR, a photosensitive membrane protein from purple membranes of the bacterium Halobacterium salinarum) and bacterial photosynthetic reaction centres have received the most attention. The energy harvesting in plants has a maximum efficiency of 5%, whereas bR, in the absence of a specific light-harvesting system, allows bacteria to utilize only 0.1-0.5% of the solar light. Recent nano-bioengineering approaches employing colloidal semiconductor and metal nanoparticles conjugated with biosystems permit the enhancement of the light-harvesting capacity of photosensitive proteins, thus providing a strong impetus to protein-based device optimisation. Fabrication of ultrathin and highly oriented films from biological membranes and photosensitive proteins is the key task for prospective bioelectronic and biophotonic applications. In this review, the main advances in techniques of preparation of such films are analyzed. Comparison of the techniques for obtaining thin films leads to the conclusion that the homogeneity and orientation of biomembrane fragments or proteins in these films depend on the method of their fabrication and increase in the following order: electrophoretic sedimentation advances in the techniques of

  16. Photosensitized oxidation of 9,10-dimethylanthracene with singlet oxygen by using a safranin O/silica composite under visible light.

    Science.gov (United States)

    Albiter, Elim; Alfaro, Salvador; Valenzuela, Miguel A

    2015-03-01

    The photosensitized oxidation of 9,10-dimethylanthracene with singlet oxygen in acetonitrile was investigated using a safranin O/silica composite as an heterogeneous delivery system of the photosensitizer. The only detected product was the corresponding endoperoxide (9,10-endoperoxianthracene) and its formation rate depended on the initial concentration of DMA, the light intensity and the amount of the composite. The kinetics of this reaction was compared with that of the reported kinetic model of photosensitized oxidations of organic compounds in homogeneous reactions. It was found that both reactions followed the same model, suggesting that the actual reaction between photoproduced singlet oxygen and 9,10-dimethylanthracene was performed in homogeneous media and the surface of the composite was not involved in the reaction.

  17. Immediate response of Ca2+ concentration in myocardial cells against oxidation stress by extracellular photosensitization reaction using Talaporfin sodium for the arrhythmia treatment application

    Science.gov (United States)

    Ogawa, Emiyu; Takahashi, Mei; Ito, Arisa; Arai, Tsunenori

    2014-02-01

    We studied the immediate response of myocardial cells by continuous observation using confocal microscope against oxidation stress by extracellular photosensitization reaction using Talaporfin sodium for tachyarrhythmia treatment application. Immediate response in order from several seconds to several minutes is required for the arrhythmia treatment since operators should judge the therapeutic effect during the tachyarrhythmia ablation procedure. To understand the immediate response of myocardial cells, we measured the intracellular Ca2+ concentration using fluo-4 AM during and after the extracellular photosensitization reaction. Talaporfin sodium concentration was varied 10-30 μg/ml. A red diode laser of 663 nm in wavelength was irradiated under the microscope with the radiant exposure of 40 J/cm2 and irradiance of 0.29 W/cm2. We observed the fluorescence image of fluo-4 AM each 400 ms during until 10 min after the photosensitization reaction. The myocardial cell beatings were stopped about 2 s after the beginning of the laser irradiation. The blebs were formed with the Ca2+ inflow. The intracellular Ca2+ was re-decreased after the bleb formation and then the cell necrosis was induced. The cell lethality 10 min after the laser irradiation was less than bleb formation ratio. The time response of the cell necrosis was shortened with the photosensitizer concentration increasing and the minimum average value was 209 s in the case of the 30 μg/ml in photosensitizer concentration and 40 J/cm2 in the radiant exposure. We think this extracellular photosensitization reaction may be applicable to tachyarrhythmia treatment in terms of its immediate response.

  18. Derivative Chameleons

    CERN Document Server

    Noller, Johannes

    2012-01-01

    We consider generalized chameleon models where the conformal coupling between matter and gravitational geometries is not only a function of the chameleon field \\phi, but also of its derivatives via higher order co-ordinate invariants. Specifically we consider the first such non-trivial conformal factor A(\\phi,X), where X is the canonical kinetic term for \\phi. The associated phenomenology is investigated and we show that such theories have a new generic mass-altering mechanism, potentially assisting the generation of a sufficiently large chameleon mass in dense environments. The most general effective potential is derived for such derivative chameleon setups and explicit examples are given. Interestingly this points us to the existence of a purely derivative chameleon protected by a shift symmetry for \\phi. We also discuss potential ghost-like instabilities associated with mass-lifting mechanisms and find another, mass-lowering and instability-free, branch of solutions. This suggests that, barring fine-tuning...

  19. Influence of singlet oxygen (1O2) generated by a lipophilic photosensitizer (Pyropheophorbide-a, PPa) on membrane and firing properties of cultured hippocampus neurons

    DEFF Research Database (Denmark)

    Breitenbach, Thomas; Ogilby, Peter Remsen; Lambert, John D. C.

    2008-01-01

    During Photodynamic Therapy (PDT) of cancer, cells are killed by 1O2, which is generated in a photosensitized process. A photosensitizer (PS) is applied to the tissue and irradiated with light to form an exited molecule. This generates 1O2 from ground state oxygen, which then induce processes...... that result in cell death (e. g. apoptosis or necrosis). We have used patch-clamp recordings from cultured neurons to provide insight into the earliest events following the light induced perturbation. Hippocampal neurons from rat embryos were cultured using standard methods and used after 10-20 DIV...

  20. Influence of red laser irradiation and photosensitizers Photoditazine and Dimegin on the growth of methicillin-resistant strain of Staphylococcus aureus

    Science.gov (United States)

    Brill, G. E.; Egorova, A. V.; Bugaeva, I. O.; Tuchina, E. S.; Morozov, O. A.; Ponomaryov, G. V.; Ushakova, O. V.

    2017-03-01

    The influence of red laser irradiation on the growth of colonies of methicillin-resistant strain of Staphylococcus aureus and photodynamic effects of the photosensitizers Photoditazine and Dimegin were performed. It was established that the red semiconductor laser (λ - 660 nm, 100 mW/cm2) at 10-, 15- and 30-mins exposure, has a direct bacteriostatic action on the growth of S. aureus. Pre-treatment of bacterial cells by Photoditazine significantly enhances the inhibitory effect. The photosensitizing action of Dimegin does not appear at influence on methicillin-resistant S. aureus.

  1. Influence of temperature on the myocardial cells death by an extracellular talaporfin sodium-induced photosensitization reaction

    Science.gov (United States)

    Ogawa, Emiyu; Takenoya, Hiromi; Arai, Tsunenori

    2016-03-01

    We have proposed to apply the photosensitization reaction in myocardium interstitial fluid using talaporfin sodium to realize less-heated electrical conduction block for a tachyarrhythmia treatment: PD Ablation®. The cytotoxicity of the extracellular photosensitization reaction efficiency may change by the talaporfin sodium binding with serum proteins. These binding would change with solution temperature. We investigated the binding behavior of talaporfin sodium with human serum albumin (HSA), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) changing solution temperature from 17 to 37°C. We also studied the photocytotoxicity change by solution temperature of 17 and 37°C measuring cell lethality by WST assay using fetal bovine serum. The binding ratio of talaporfin sodium with HDL and LDL decreased 6.3% and 12.8% with temperature increasing from 17 to 37°C. There was no significant difference in the case of HSA. The cell lethality was increased about 30% with temperature increasing from 17 to 37°C. The myocardium tissue temperature increase was reported that less than 5°C in the case of our PD Ablation®. We think that the photocytotoxicity change by these temperature increasing would be negligible in our PD Ablation®. We suggest that the temperature maintaining would be necessary to keep the photocytotoxicity efficiency in the case of the open surgery that would cause the tissue surface temperature decreasing.

  2. Photosensitized mefloquine induces ROS-mediated DNA damage and apoptosis in keratinocytes under ambient UVB and sunlight exposure.

    Science.gov (United States)

    Yadav, Neera; Dwivedi, Ashish; Mujtaba, Syed Faiz; Verma, Ankit; Chaturvedi, Rajnish; Ray, Ratan Singh; Singh, Gajendra

    2014-10-01

    The present study illustrates the photosensitizing behavior of mefloquine (MQ) in human skin keratinocytes under ambient doses of UVB and sunlight exposure. Photochemically, MQ generated reactive oxygen species superoxide radical, hydroxyl radical, and singlet oxygen through type I and type II photodynamic reactions, respectively, which caused photooxidative damage to DNA and formed localized DNA lesions cyclobutane pyrimidine dimers. Photosensitized MQ reduced the viability of keratinocytes to 25 %. Significant level of intracellular reactive oxygen species (ROS) generation was estimated through fluorescence probe DCF-H2. Increased apoptotic cells were evident through AO/EB staining and phosphatidyl serine translocation in cell membrane. Single-stranded DNA damage was marked through single-cell gel electrophoresis. Mitochondrial membrane depolarization and lysosomal destabilization were evident. Upregulation of Bax and p21 and downregulation of Bcl-2 genes and corresponding protein levels supported apoptotic cell death of keratinocyte cells. Cyclobutane pyrimidine dimers (CPDs) were confirmed through immunofluorescence. In addition, hallmarks of apoptosis and G2/M phase cell cycle arrest were confirmed through flow cytometry analysis. Our findings suggest that MQ may damage DNA and produce DNA lesions which may induce differential biological responses in the skin on brief exposure to UVB and sunlight.

  3. Photodynamic therapy (PDT) and photodiagnosis (PD) using endogenous photosensitization induced by 5-aminolevulinic acid (ALA): current clinical and development status

    Science.gov (United States)

    Marcus, Stuart L.; Sobel, Russel S.; Golub, Allyn L.; Carroll, Ronald L.; Lundahl, Scott L.; Shulman, D. Geoffrey

    1996-04-01

    Exogenous provision of ALA to many tissues results in the accumulation of sufficient quantities of the endogenous photosensitizer protoporphyrin IX, (PpIX), to produce a photodynamic effect. Therefore, ALA may be considered the only current PDT agent in clinical development which is a biochemical precursor of a photosensitizer. Topical ALA application, followed by exposure to activating light (ALA PDT), has been reported effective for the treatment of a variety of dermatologic diseases including cutaneous T-cell lymphoma, superficial basal cell carcinoma, Bowen's disease, and actinic (solar) keratoses, and is also being examined for treatment of acne and hirsutism. PpIX induced by ALA application also may serve as a fluorescence detection marker for photodiagnosis (PD) of malignant and pre- malignant conditions of the urinary bladder and other organs. Local internal application of ALA has also been used for selective endometrial ablation in animal model systems and is beginning to be examined in human clinical studies. Systemic, oral administration of ALA has been used for ALA PDT of superficial head and neck cancer, various gastrointestinal cancers, and the condition known as Barrett's esophagus. This brief paper reviews the current clinical and development status of ALA PDT.

  4. Low-temperature processable inherently photosensitive polyimide as a gate insulator for organic thin-film transistors

    Science.gov (United States)

    Pyo, Seungmoon; Son, Hyunsam; Choi, Kil-Yeong; Yi, Mi Hye; Hong, Sung Kwon

    2005-03-01

    We have fabricated organic thin-film transistors (OTFTs) on polyethersulfone substrate using low-temperature processable, inherently photosensitive polyimide as the gate insulator and pentacene as the active material. The polyimide was prepared through two-step reaction. The polyimide precursor, poly(amic acid), was prepared from a dianhydride and aromatic diamine through a polycondensation reaction, and subsequently converted to its corresponding polyimide by a chemical imidization. Photolithographic properties of the polyimide are investigated. The pattern resolution of the cured polyimide was about 50μm. The pentacene OTFTs with the patterned polyimide were obtained with a carrier mobility of 0.1cm2/Vs and ION/IOFF of 5×105. The OTFT characteristics are discussed in more detail with respect to the electrical properties of the photosensitive polyimide thin film. This low-temperature photopatternable polyimide paves the way for the easy and low-cost fabrication of OTFT arrays without expensive and complicated photolithography and dry etching processes.

  5. Structural factors and mechanisms underlying the improved photodynamic cell killing with silicon phthalocyanine photosensitizers directed to lysosomes versus mitochondria.

    Science.gov (United States)

    Rodriguez, Myriam E; Zhang, Ping; Azizuddin, Kashif; Delos Santos, Grace B; Chiu, Song-mao; Xue, Liang-yan; Berlin, Jeffery C; Peng, Xinzhan; Wu, Hongqiao; Lam, Minh; Nieminen, Anna-Liisa; Kenney, Malcolm E; Oleinick, Nancy L

    2009-01-01

    The phthalocyanine photosensitizer Pc 4 has been shown to bind preferentially to mitochondrial and endoplasmic reticulum membranes. Upon photoirradiation of Pc 4-loaded cells, membrane components, especially Bcl-2, are photodamaged and apoptosis, as indicated by activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase, is triggered. A series of analogs of Pc 4 were synthesized, and the results demonstrate that Pcs with the aminopropylsiloxy ligand of Pc 4 or a similar one on one side of the Pc ring and a second large axial ligand on the other side of the ring have unexpected properties, including enhanced cell uptake, greater monomerization resulting in greater intracellular fluorescence and three-fold higher affinity constants for liposomes. The hydroxyl-bearing axial ligands tend to reduce aggregation of the Pc and direct it to lysosomes, resulting in four to six times more killing of cells, as defined by loss of clonogenicity, than with Pc 4. Whereas Pc 4-PDT photodamages Bcl-2 and Bcl-xL, Pc 181-PDT causes much less photodamage to Bcl-2 over the same dose-response range relative to cell killing, with earlier cleavage of Bid and slower caspase-3-dependent apoptosis. Therefore, within this series of photosensitizers, these hydroxyl-bearing axial ligands are less aggregated than is Pc 4, tend to localize to lysosomes and are more effective in overall cell killing than is Pc 4, but induce apoptosis more slowly and by a modified pathway.

  6. Photodynamic therapy with the phthalocyanine photosensitizer Pc 4: the case experience with preclinical mechanistic and early clinical-translational studies.

    Science.gov (United States)

    Miller, Janine D; Baron, Elma D; Scull, Heather; Hsia, Andrew; Berlin, Jeffrey C; McCormick, Thomas; Colussi, Valdir; Kenney, Malcolm E; Cooper, Kevin D; Oleinick, Nancy L

    2007-11-01

    Photodynamic therapy (PDT) is emerging as a promising non-invasive treatment for cancers. PDT involves either local or systemic administration of a photosensitizing drug, which preferentially localizes within the tumor, followed by illumination of the involved organ with light, usually from a laser source. Here, we provide a selective overview of our experience with PDT at Case Western Reserve University, specifically with the silicon phthalocyanine photosensitizer Pc 4. We first review our in vitro studies evaluating the mechanism of cell killing by Pc 4-PDT. Then we briefly describe our clinical experience in a Phase I trial of Pc 4-PDT and our preliminary translational studies evaluating the mechanisms behind tumor responses. Preclinical work identified (a) cardiolipin and the anti-apoptotic proteins Bcl-2 and Bcl-xL as targets of Pc 4-PDT, (b) the intrinsic pathway of apoptosis, with the key participation of caspase-3, as a central response of many human cancer cells to Pc 4-PDT, (c) signaling pathways that could modify apoptosis, and (d) a formulation by which Pc 4 could be applied topically to human skin and penetrate at least through the basal layer of the epidermis. Clinical-translational studies enabled us to develop an immunohistochemical assay for caspase-3 activation, using biopsies from patients treated with topical Pc 4 in a Phase I PDT trial for cutaneous T-cell lymphoma. Results suggest that this assay may be used as an early biomarker of clinical response.

  7. Light-triggered liposomal cargo delivery platform incorporating photosensitizers and gold nanoparticles for enhanced singlet oxygen generation and increased cytotoxicity

    Science.gov (United States)

    Kautzka, Zofia; Clement, Sandhya; Goldys, Ewa M; Deng, Wei

    2017-01-01

    We developed light-triggered liposomes incorporating 3–5 nm hydrophobic gold nanoparticles and Rose Bengal (RB), a well-known photosensitizer used for photodynamic therapy. Singlet oxygen generated by these liposomes with 532 nm light illumination was characterized for varying the molar ratio of lipids and gold nanoparticles while keeping the amount of RB constant. Gold nanoparticles were found to enhance the singlet oxygen generation rate, with a maximum enhancement factor of 1.75 obtained for the molar ratio of hydrogenated soy l-α-phosphatidylcholine:1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(hexanoylamine):gold of 57:5:17 compared with liposomes loaded with RB alone. The experimental results could be explained by the local electric field enhancement caused by gold nanoparticles. We further assessed cellular cytotoxicity of gold-loaded liposomes by encapsulating an antitumor drug, doxorubicin (Dox); such Dox-loaded liposomes were applied to human colorectal cancer cells (HCT116) and exposed to light. Gold-loaded liposomes containing RB and Dox where Dox release was triggered by light were found to exhibit higher cytotoxicity compared with the liposomes loaded with RB and Dox alone. Our results indicate that gold-loaded liposomes incorporating photosensitizers may serve as improved agents in photodynamic therapy and chemotherapy. PMID:28203076

  8. Two-photon polymerization technique for microfabrication of CAD-designed 3D scaffolds from commercially available photosensitive materials.

    Science.gov (United States)

    Ovsianikov, Aleksandr; Schlie, Sabrina; Ngezahayo, Anaclet; Haverich, Axel; Chichkov, Boris N

    2007-01-01

    We report on recent advances in the fabrication of three-dimensional (3D) scaffolds for tissue engineering and regenerative medicine constructs using a two-photon polymerization technique (2PP). 2PP is a novel CAD/CAM technology allowing the fabrication of any computer-designed 3D structure from a photosensitive polymeric material. The flexibility of this technology and the ability to precisely define 3D construct geometry allows issues associated with vascularization and patient-specific tissue fabrication to be directly addressed. The fabrication of reproducible scaffold structures by 2PP is important for systematic studies of cellular processes and better understanding of in vitro tissue formation. In this study, 2PP was applied for the generation of 3D scaffold-like structures, using the photosensitive organic-inorganic hybrid polymer ORMOCER (ORganically MOdified CERamics) and epoxy-based SU8 materials. By comparing the proliferation rates of cells grown on flat material surfaces and under control conditions, it was demonstrated that ORMOCER and SU8 are not cytotoxic. Additional tests show that the DNA strand breaking of GFSHR-17 granulosa cells was not affected by the presence of ORMOCER. Furthermore, gap junction conductance measurements revealed that ORMOCER did not alter the formation of cell-cell junctions, critical for functional tissue growth. The possibilities of seeding 3D structures with cells were analysed. These studies demonstrate the great potential of 2PP technique for the manufacturing of scaffolds with controlled topology and properties.

  9. Cellular responses to chlorin-based photosensitizer DH-II-24 under darkness in human gastric adenocarcinoma AGS cells.

    Science.gov (United States)

    Lim, Young-Cheol; Yoo, Je-Ok; Kang, Seong-Sik; Kim, Young-Myeong; Ha, Kwon-Soo

    2011-03-01

    We investigated cellular responses to chlorin-based photosensitizer DH-II-24 under darkness in human gastric adenocarcinoma AGS cells. Cells were loaded with 0.5-10 μg/mL DH-II-24 for 12 h, and intracellular reactive oxygen species (ROS) and intracellular Ca(2+) levels, in situ tissue transglutaminase (tTGase) activity, cell viability, cell morphology and cell cycle were examined. DH-II-24 treatment had no effect on intracellular ROS production or cell morphology, and did not induce cell detachment at any concentrations tested. In addition, cell viability and cell cycle progression were not altered by the photosensitizer. However, DH-II-24 treatment elevated the basal level of intracellular Ca(2+) in a dose-dependent manner and inhibited tTGase activity without affecting tTGase expression levels. Furthermore, DH-II-24 inhibited lysophosphatidic acid-induced activation of tTGase in a dose-dependent manner. In contrast, photodynamic therapy (PDT) with 1 μg/mL DH-II-24 significantly elevated intracellular ROS and in situ tTGase activity in parallel with a rapid and large increase in intracellular Ca(2+) levels. DH-II-24-mediated PDT decreased cell viability and induced cell detachment. These results demonstrate that DH-II-24 treatment alone under darkness induced different cellular responses to DH-II-24-mediated PDT.

  10. Photodynamic antimicrobial chemotherapy using zinc phthalocyanine derivative for bacterial skin infection

    Science.gov (United States)

    Chen, Zhuo; Zhang, Yaxin; Li, Linsen; Zhou, Shanyong; Chen, Jincan; Hu, Ping; Huang, Mingdong

    2014-09-01

    Folliculitis, furunculosis and acne vulgaris are very common skin disorders of the hair follicles and are associated with large grease-producing (sebaceous) glands. Although the detailed mechanisms involved these skin disorders are not fully understood, it is believed that the bacteria Propionibacterium acnes and Staphylococcus aureus are the key pathogenic factors involved. Conventional treatments targeting the pathogenic factors include a variety of topical and oral medications such as antibiotics. The wide use of antibiotics leads to bacterial resistance, and hence there is a need for new alternatives in above bacterial skin treatment. Photodynamic antimicrobial chemotherapy (PACT) is based on an initial photosensitization of the infected area, followed by irradiation with visible light, producing singlet oxygen which is cytotoxic to bacteria. Herein we reported a zinc phthalocyanine derivative, pentalysine β-carbonylphthalocyanine zinc (ZnPc-(Lys)5) and its PACT effect for the bacteria involved in these skin infections. Our results demonstrated strong bactericidal effects of this photosensitizer on both strains of the bacteria, suggesting ZnPc-(Lys)5 as a promising antimicrobial photosensitizer for the treatment of infectious diseases caused by these bacteria.

  11. Derivative chameleons

    Science.gov (United States)

    Noller, Johannes

    2012-07-01

    We consider generalized chameleon models where the conformal coupling between matter and gravitational geometries is not only a function of the chameleon field phi, but also of its derivatives via higher order co-ordinate invariants (such as ∂μphi∂μphi,squphi,...). Specifically we consider the first such non-trivial conformal factor A(phi,∂μphi∂μphi). The associated phenomenology is investigated and we show that such theories have a new generic mass-altering mechanism, potentially assisting the generation of a sufficiently large chameleon mass in dense environments. The most general effective potential is derived for such derivative chameleon setups and explicit examples are given. Interestingly this points us to the existence of a purely derivative chameleon protected by a shift symmetry for phi → phi+c. We also discuss potential ghost-like instabilities associated with mass-lifting mechanisms and find another, mass-lowering and instability-free, branch of solutions. This suggests that, barring fine-tuning, stable derivative models are in fact typically anti-chameleons that suppress the field's mass in dense environments. Furthermore we investigate modifications to the thin-shell regime and prove a no-go theorem for chameleon effects in non-conformal geometries of the disformal type.

  12. Global Derivatives

    DEFF Research Database (Denmark)

    Andersen, Torben Juul

    ." - Steen Parsholt, Chairman and CEO, Aon Nordic Region. "Andersen has done a wonderful job of developing a comprehensive text that deals with risk management in global markets. I would recommend this book to any student or businessman who has a need to better understand the risks and risk management...... management practice. Of particular note is the global and integrated approach chosen in this book which should be of special interest to aspiring managers active in global and international markets." - Dr Jean-Pierre Zigrand, Lecturer in Finance, London School of Economics, UK. More than 90 per cent...... management situations. Its key features include: derivatives are introduced in a global market perspective; describes major derivative pricing models for practical use, extending these principles to valuation of real options; practical applications of derivative instruments are richly illustrated...

  13. Electricity derivatives

    CERN Document Server

    Aïd, René

    2015-01-01

    Offering a concise but complete survey of the common features of the microstructure of electricity markets, this book describes the state of the art in the different proposed electricity price models for pricing derivatives and in the numerical methods used to price and hedge the most prominent derivatives in electricity markets, namely power plants and swings. The mathematical content of the book has intentionally been made light in order to concentrate on the main subject matter, avoiding fastidious computations. Wherever possible, the models are illustrated by diagrams. The book should allow prospective researchers in the field of electricity derivatives to focus on the actual difficulties associated with the subject. It should also offer a brief but exhaustive overview of the latest techniques used by financial engineers in energy utilities and energy trading desks.

  14. The vascular response observation by the monitoring of the photosensitizer, oxygen, and blood flow during the high intensity pulsed excitation photodynamic therapy 1h after water-soluble photosensitizer intravenous injection

    Science.gov (United States)

    Hakomori, S.; Matsuo, H.; Arai, T.

    2008-02-01

    We investigated the correlation between the therapeutic effect by early irradiation Photodynamic Therapy (PDT) and vascular response. The early irradiation PDT has been proposed by our group. This PDT protocol is that pulse laser irradiates to tumors 1 h after intravenous injection of water-soluble photosensitizer. The intact layer appeared over the well treated layer, when the early irradiation PDT was performed at rat prostate subcutaneous tumors with high intensity pulse laser (over 1 MW/cm2 in peak intensity) and Talaporfin sodium. In order to clarify the phenomenon mechanism, we monitored blood volume, surface temperature, photosensitizer amount, and oxygen saturation during the PDT. The rat prostate subcutaneous tumor was irradiated with excimer dye laser light at 1 h after the intravenous injection. The photosensitizer dose wa 2.0 mg/kg, and the pulse energy density was 2.5 mJ/cm2 (low intensity) or 10 mJ/cm2 (high intensity). Under the low intensity pulsed PDT, the fluorescence amount was decreasing gently during the irradiation, and the blood volume and oxygen saturation started decreasing just after the irradiation. Under the hgh intensity pulsed PDT, the fluorescence amount was decreaased rapidly for 20 s after the irradiation started. The blood volume and oxygen saturation were temporally decreased during the irradiation, and recovered at 48 hrs after the irradiation. According to these results, under the low intensity pulsed PDT, the blood vessel located near the surface started closing just after the irradiation. On the other hand, under the high intensity pulsed PDT the blood vessel was closing for 20 s after the irradiation started, moreover, the blood flow recovered at 48 hrs after the irradiation. We concluded that the vascular response depended on the pulse energy density, and then the therapeutic effect was attributed to the difference of the vascular response. In other words, the surface intact layer could be considered to be induced the

  15. Photodynamic activity of tetraazachlorin derivate studied in vivo

    Directory of Open Access Journals (Sweden)

    V. I. Ivanova-Radkevich

    2013-01-01

    Full Text Available The results of investigation for photodynamic activity of new tetraazachlorin derivate – tetramethyltribenzotetraazachlorin, synthesized in Research Institute of Organic Intermediates and Dyes. The study was performed on female mice of СВА line. The tumor model was transferred solid ascetic sarcoma S-37. The samples of photosensitizer, previously solubilized in 10% aqueou s solution ofCremophor EL, injected to mice intravenously on the 7th day of tumor growth in dose of 1–2 mg/kg. Two hours later the irradiation of sensitized tumor using light emitting diode device in a maximal wavelength of 755 nm (light power density – 50 mW/cm2, maximal total light dose – 300 J/cm2 was performed. The efficacy of photodynamic therapy was assessed by growth inhibition rates in the study group comparing with control group. The study showed that photodynamic therapy with investigated sample in dose of 2 mg/kg and light dose of 300 J/cm2 significantly inhibited the tumor growth (inhibition rate of 70–80% within 20 days, indicating prospectivity of subsequent investigations of tetraazachlorin as photosensitizer for photodynamic therapy of malignant tumors. 

  16. Near infrared light-driven water oxidation in a molecule-based artificial photosynthetic device using an upconversion nano-photosensitizer

    NARCIS (Netherlands)

    Liu, X.; Chen, H.C.; Kong, X.; Zhang, Y.; Tu, L.; Chang, Y.; Wu, F.; Wang, T.; Reek, J.N.H.; Brouwer, A.M.; Zhang, H.

    2015-01-01

    We provide the first demonstration of a near infrared light driven water oxidation reaction in a molecule-based artificial photosynthetic device using an upconversion nano-photosensitizer. One very attractive advantage of this system is that using NIR light irradiation does not cause significant pho

  17. Evaluation of phototoxic and photogenotoxic risk associated with the use of photosensitizers in suntan preparations: application to tanning preparations containing bergamot oil.

    Science.gov (United States)

    Moysan, A; Morlière, P; Averbeck, D; Dubertret, L

    1993-01-01

    Bases for the elaboration of a standardized protocol are proposed for studying phototoxic effects of skin tanning preparations containing photosensitizing agents. The experimental procedure includes in vivo phototoxicity tests, evaluation of the photogenotoxic risk and determination of the photosensitizer concentration in plasma after topical application. This procedure was carried out with tanning preparations containing a well-known photosensitizer, 5-methoxypsoralen, as a component of bergamot oil. The whole study has been performed using topical application of the commercial suntan product, i.e. containing the sunscreens and all other components. Whereas the exposure to solar simulated radiation never triggered any phototoxic response, a photosensitizing effect was observed for skin type I volunteers exposed to high doses of ultraviolet A. The transepidermal penetration resulted in a 5-methoxypsoralen concentration of 1-4 ng/ml in the suction blister fluid. The photogenotoxicity of this suction blister fluid containing 5-methoxypsoralen and also other ingredients of the tanning preparation was assayed on yeast cells and was found to be rather low. 5-Methoxypsoralen was also detected in plasma after repeated applications but at low concentrations (about 1 ng/ml) which do not present a potential risk for systemic ocular effects.

  18. A comparative analysis of silicon phthalocyanine photosensitizers for in vivo photodynamic therapy of RIF-1 tumors in C3H mice.

    Science.gov (United States)

    Anderson, C Y; Freye, K; Tubesing, K A; Li, Y S; Kenney, M E; Mukhtar, H; Elmets, C A

    1998-03-01

    Photofrin photodynamic therapy (PDT) has recently received FDA approval for the palliative treatment of totally and partially obstructing esophageal malignancies. However, there is a need for new PDT photosensitizers because Photofrin has a number of undesirable features. The purpose of this study was to evaluate the efficacy of four amine-bearing silicon phthalocyanines--Pc4, Pc10, Pc12 and Pc18--as potential PDT photosensitizers. Equimolar concentrations of these Pc were found to be highly effective at causing the regression of RIF-1 tumors transplanted to C3H/HeN mice. The amount of Pc4 necessary to cause an equivalent amount of tumor regression in this model system was substantially less than the amount of Photofrin. The cutaneous phototoxicity of the silicon Pc photosensitizer was assessed by the utilization of the murine ear-swelling model. When C3H mice were exposed to 167 J/cm2 of polychromatic visible light from a UVB-filtered solar simulator, which emitted UV radiation and visible light above 320 nm, the Pc produced little, if any, cutaneous photosensitivity. These results indicate that Pc4, Pc10, Pc12 and Pc18 are at least as effective as Photofrin in PDT protocols, while at the same time addressing many of the drawbacks of Photofrin.

  19. Photodynamic efficacy of liposome-delivered hypocrellin B in microvascular endothelial cells in vitro and chicken combs in vivo: a potential photosensitizer for port wine stain

    Science.gov (United States)

    Chen, H. X.; Yang, Z. F.; Zou, X. B.; Zhu, J. G.; Deng, H.; Zhao, J. Q.; Gu, Y.

    2013-02-01

    Photodynamic therapy (PDT) has been proved a successful method for port wine stain (PWS), but the prolonged skin photosensitivity induced by the photosensitizers used currently seriously limits the clinical application of PDT. In this study, we investigate the feasibility of hypocrellin B (HB), a promising second-generation photosensitizer for the treatment of PWS. The photodynamic effect of liposome-delivered HB was evaluated in vitro with microvascular endothelial cells (MEC) and in vivo with chicken combs. The dark cytotoxicity and photocytotoxicity of liposomal HB in MEC were evaluated using the MTT assay. Gross and histological examinations were performed to investigate the selective occlusion of the superficial dermal microvasculature in the chicken comb. The result showed that photocytotoxicity of liposomal HB was dependent on both light dose and drug concentration. PDT with HB (0.5-1 mg kg-1) and a light dose of 120 J cm-2 showed selective destruction of the superficial dermal microvasculature of the chicken comb, leaving the overlying epidermis intact. This is the first study to investigate the potential efficacy of HB-PDT as a novel modality for the treatment of PWS. These findings suggest that liposomal HB is a safe and effective photosensitizer for PWS.

  20. Raman spectroscopic study on structure of human immunodeficiency virus (HIV) and hypericin-induced photosensitive damage of HIV

    Institute of Scientific and Technical Information of China (English)

    XU; Yiming; LU; Chuanzong

    2005-01-01

    The first Raman spectra of HIV1- HIV2 in human sera and hypericin-induced photosensitive damage of the virus have been obtained. The prominent Raman lines in the spectra are assigned respectively to the carbohydrates of viral glycoprotein, RNA, protein and lipid. The spectra are dominated by Raman scattering of the carbohydrates. The lines of D-Mannose and N-acetylglucosamine in carbohydrates are obvious and there is a β-configuration in the anomeric C1 position in D-Mannose. The viral RNA duplexes bound assumes an A-form geometry. The lines of backbone phosphate group, bases (involving interbase hydrogen bonding) and ribose of the RNA are complete and distinct. The secondary structure of the viral protein maintains β-helix, β-sheet, β-turn and random coil. Its side chains are rich and vary from tryptophan, phenylalanine and "buried" tyrosine; the stable conformation of the S-S bond of gauche-gauche-gauche; the two forms of C-S bonds of gauche and trans ; to sulfhydrl group and ionized and unionized carboxyl groups. The viral lipid bilayer molecules are probably in the liquid ordered phase or the gel phase. It was observed that the hypericin-induced photosensitive damage of HIV1-HIV2 in human sera changed various components of HIV1-HIV2 in different degrees : The orderly A-form viral RNA would become a disordered viral RNA. There were a breakage of interbase hydrogen bonds and disruption of vertical base-base stacking interactions. In addition, the groups of ribos and four bases were damaged obviously. A decrease in ordered structure (α-helix and α-sheet) of viral protein is accompanied by an increase in random coil. The Tyr buried in the three-dimensional structure of protein was damaged, but it was still "buried" and the damage of C-S bond of trans form was stronger. The groups of carbohydrates, including D-Mannos and N-acetyl glucosamine, in viral envelope glycoprotein had also been changed. The hydrophilic C-N bond of choline in viral lipid was damaged