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Sample records for membranes utilizing porphyrins

  1. Peripheral-type benzodiazepine receptor: a protein of mitochondrial outer membranes utilizing porphyrins as endogenous ligands

    SciTech Connect

    Snyder, S.H.; Verma, A.; Trifiletti, R.R.

    1987-10-01

    The peripheral-type benzodiazepine receptor is a site identified by its nanomolar affinity for (/sup 3/H)diazepam, similar to the affinity of diazepam for the central-type benzodiazepine receptor in the brain. The peripheral type benzodiazepine receptor occurs in many peripheral tissues but has discrete localizations as indicated by autoradiographic studies showing uniquely high densities of the receptors in the adrenal cortex and in Leydig cells of the testes. Subcellular localization studies reveal a selective association of the receptors with the outer membrane of mitochondria. Photoaffinity labeling of the mitochondrial receptor with (/sup 3/H)flunitrazepam reveals two discrete labeled protein bands of 30 and 35 kDa, respectively. The 35-kDa band appears to be identical with the voltage-dependent anion channel protein porin. Fractionation of numerous peripheral tissues reveals a single principal endogenous ligand for the receptor, consisting of porphyrins, which display nanomolar affinity. Interactions of porphyrins with the mitochondrial receptor may clarify its physiological role and account for many pharmacological actions of benzodiazepines.

  2. Porphyrins

    NASA Astrophysics Data System (ADS)

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

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

  3. Porphyrins

    DOEpatents

    Wijesekera, Tilak; Lyons, James E.; Ellis, Jr., Paul E.

    1996-01-01

    The invention comprises new compositions of matter, which are iron, manganese, cobalt or ruthenium complexes of porphyrins having hydrogen, haloalkyl or haloaryl groups in meso positions, two of the opposed meso atoms or groups being hydrogen or haloaryl, and two of the opposed meso atoms or groups being hydrogen or haloalkyl, but not all four of the meso atoms or groups being hydrogen. The invention also comprises new compositions of matter in which all four of the meso positions are substituted with haloalkyl groups and the beta positions are substituted with halogen atoms. A new method of synthesizing porphyrinogens is also provided. The novel compositions and others made according to the process of the invention are useful as hydrocarbon conversion catalysts; for example, for the oxidation of alkanes and the decomposition of hydroperoxides.

  4. Porphyrins

    DOEpatents

    Wijesekera, T.; Lyons, J.E.; Ellis, P.E. Jr.

    1996-11-05

    The invention comprises new compositions of matter, which are iron, manganese, cobalt or ruthenium complexes of porphyrins having hydrogen, haloalkyl or haloaryl groups in meso positions, two of the opposed meso atoms or groups being hydrogen or haloaryl, and two of the opposed meso atoms or groups being hydrogen or haloalkyl, but not all four of the meso atoms or groups being hydrogen. The invention also comprises new compositions of matter in which all four of the meso positions are substituted with haloalkyl groups and the beta positions are substituted with halogen atoms. A new method of synthesizing porphyrinogens is also provided. The novel compositions and others made according to the process of the invention are useful as hydrocarbon conversion catalysts; for example, for the oxidation of alkanes and the decomposition of hydroperoxides.

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

    PubMed Central

    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

  6. Porphyrin network polymers prepared via a click reaction and facilitated oxygen permeation through their membranes.

    PubMed

    Chikushi, Natsuru; Ohara, Emiko; Hisama, Ayako; Nishide, Hiroyuki

    2014-05-01

    Network polymers of cobaltporphyrin derivatives are prepared by a facile click reaction via the Michael addition of acetoacetate-substituted tetraphenyl cobaltporphyrin and tri- or tetra-acrylates. The conversion is saturated for 1 h in the presence of a catalyst, which almost reaches the same gelation point of the formed network polymers. Deeply and homogeneously red-colored membranes with a sub-micrometer thickness are yielded on a porous supporting membrane. They are still tough even with a very high content of the rigid porphyrin residue. The oxygen permeability is high, at 10-100 Barrer, and the oxygen/nitrogen permselectivity (PO2/PN2) is significantly enhanced with the porphyrin content reaching 30, for the membranes with ca. 70 wt% porphyrin content.

  7. Temperature-dependent conformations of a membrane supported zinc porphyrin tweezer by 2D fluorescence spectroscopy.

    PubMed

    Widom, Julia R; Lee, Wonbae; Perdomo-Ortiz, Alejandro; Rappoport, Dmitrij; Molinski, Tadeusz F; Aspuru-Guzik, Alán; Marcus, Andrew H

    2013-07-25

    We studied the equilibrium conformations of a zinc porphyrin tweezer composed of two carboxylphenyl-functionalized zinc tetraphenyl porphyrin subunits connected by a 1,4-butyndiol spacer, which was suspended inside the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) liposomes. By combining phase-modulation two-dimensional fluorescence spectroscopy (2D FS) with linear absorbance and fluorimetry, we determined that the zinc porphyrin tweezer adopts a mixture of folded and extended conformations in the membrane. By fitting an exciton-coupling model to a series of data sets recorded over a range of temperatures (17-85 °C) and at different laser center wavelengths, we determined that the folded form of the tweezer is stabilized by a favorable change in the entropy of the local membrane environment. Our results provide insights toward understanding the balance of thermodynamic factors that govern molecular assembly in membranes.

  8. Porphyrin-functionalized dendrimers: synthesis and application as recyclable photocatalysts in a nanofiltration membrane reactor.

    PubMed

    Chavan, Suhas A; Maes, Wouter; Gevers, Lieven E M; Wahlen, Joos; Vankelecom, Ivo F J; Jacobs, Pierre A; Dehaen, Wim; De Vos, Dirk E

    2005-11-04

    The convergent synthesis of a series of porphyrin-functionalized pyrimidine dendrimers has been accomplished by a procedure involving the nucleophilic aromatic substitution (NAS) as a key reaction step. The resulting dendritic porphyrin catalysts show high activity in the light-induced generation of singlet oxygen ((1)O2) from ground-state oxygen. These materials are synthetically useful photosensitizers for the oxidation of various olefinic compounds to the corresponding allylic hydroperoxides. Catalytic activities and regio- and stereoselectivities of the dendritic photosensitizers are comparable to those observed for mononuclear porphyrin catalysts. Recycling of the dendrimer-enlarged homogeneous photocatalysts was possible by solvent-resistant nanofiltration (SRNF) by using an oxidatively stable membrane consisting of a polysiloxane polymer and ultrastable Y zeolite as inorganic filler. Moreover, this membrane technology provides a safe way to isolate the hydroperoxide products under very mild conditions. The membrane showed high retention for the macromolecular catalysts, even in chlorinated solvents, but some oxidative degradation of the porphyrin units of the dendrimer was observed over multiple catalytic runs.

  9. Battery utilizing ceramic membranes

    DOEpatents

    Yahnke, Mark S.; Shlomo, Golan; Anderson, Marc A.

    1994-01-01

    A thin film battery is disclosed based on the use of ceramic membrane technology. The battery includes a pair of conductive collectors on which the materials for the anode and the cathode may be spin coated. The separator is formed of a porous metal oxide ceramic membrane impregnated with electrolyte so that electrical separation is maintained while ion mobility is also maintained. The entire battery can be made less than 10 microns thick while generating a potential in the 1 volt range.

  10. Battery utilizing ceramic membranes

    DOEpatents

    Yahnke, M.S.; Shlomo, G.; Anderson, M.A.

    1994-08-30

    A thin film battery is disclosed based on the use of ceramic membrane technology. The battery includes a pair of conductive collectors on which the materials for the anode and the cathode may be spin coated. The separator is formed of a porous metal oxide ceramic membrane impregnated with electrolyte so that electrical separation is maintained while ion mobility is also maintained. The entire battery can be made less than 10 microns thick while generating a potential in the 1 volt range. 2 figs.

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

    PubMed

    Lisak, Grzegorz; Tamaki, Takashi; Ogawa, Takuji

    2017-04-04

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

  12. A Novel Porphyrin-Containing Polyimide Nanofibrous Membrane for Colorimetric and Fluorometric Detection of Pyridine Vapor

    PubMed Central

    Lv, Yuanyuan; Zhang, Yani; Du, Yanglong; Xu, Jiayao; Wang, Junbo

    2013-01-01

    A novel zinc porphyrin-containing polyimide (ZPCPI) nanofibrous membrane for rapid and reversible detection of trace amounts of pyridine vapor is described. The membrane displays a distinct color change, as well as dramatic variations in absorption and fluorescent emission spectra, upon exposure to pyridine vapor. This condition allows the detection of the analyte at concentrations as low as 0.041 ppm. The vapochromic and spectrophotometric responses of the membrane are attributed to the formation of the ZPCPI-pyridine complex upon axial coordination. From surface plasmon resonance analysis, the affinity constant of ZPCPI-pyridine complex was calculated to be (3.98 ± 0.25) × 104 L·mol−1. The ZPCPI nanofibrous membrane also showed excellent selectivity for pyridine vapor over other common amines, confirming its applicability in the manufacture of pyridine-sensitive gas sensors. PMID:24256976

  13. Graphene Oxide Nanofiltration Membranes Stabilized by Cationic Porphyrin for High Salt Rejection.

    PubMed

    Xu, Xiao-Ling; Lin, Fu-Wen; Du, Yong; Zhang, Xi; Wu, Jian; Xu, Zhi-Kang

    2016-05-25

    Swelling has great influences on the structure stability and separation performance of graphene oxide laminate membranes (GOLMs) for water desalination and purification. Herein, we report cross-linked GOLMs from GO assembled with cationic tetrakis(1-methyl-pyridinium-4-yl)porphyrin (TMPyP) by a vacuum-assisted strategy. The concave nonoxide regions (G regions) of GO are used as cross-linking sites for the first time to precisely control the channel size for water permeation and salt ion retention. Channels around 1 nm are constructed by modulating the assembly ratio of TMPyP/GO, and these cross-linked GOLMs show high salt rejection.

  14. Enhanced Electron Lifetimes in Dye-Sensitized Solar Cells Using a Dichromophoric Porphyrin: The Utility of Intermolecular Forces.

    PubMed

    Zhao, Long; Wagner, Pawel; van der Salm, Holly; Gordon, Keith C; Mori, Shogo; Mozer, Attila J

    2015-10-07

    Electron lifetimes in dye-sensitized solar cells employing a porphyrin dye, an organic dye, a 1:1 mixture of the two dyes, and a dichromophoric dye design consisting of the two dyes using a nonconjugated linker were measured, suggesting that the dispersion force of the organic dyes has a significant detrimental effect on the electron lifetime and that the dichromophoric design can be utilized to control the effect of the dispersion force.

  15. Iron porphyrin-modified PVDF membrane as a biomimetic material and its effectiveness on nitric oxide binding

    NASA Astrophysics Data System (ADS)

    Can, Faruk; Demirci, Osman Cahit; Dumoulin, Fabienne; Erhan, Elif; Arslan, Leyla Colakerol; Ergenekon, Pınar

    2017-10-01

    Nitric oxide (NO) is a reactive gas well-known as an air pollutant causing severe environmental problems. NO is also an important signaling molecule having a strong affinity towards heme proteins in the body. Taking this specialty as a model, a biomimetic membrane was developed by modification of the membrane surface with iron-porphyrin which depicts very similar structure to heme proteins. In this study, PVDF membrane was coated with synthesized (4-carboxyphenyl)-10,15,20-triphenyl-porphyrin iron(III) chloride (FeCTPP) to promote NO fixation on the surface. The coated membrane was characterized in terms of ATR-IR spectra, contact angle measurement, chemical composition, and morphological structure. Contact angle of original PVDF first decreased sharply after plasma treatment and surface polymerization steps but after incorporation of FeCTPP, the surface acquired its hydrophobicity again. NO binding capability of modified membrane surface was evaluated on the basis of X-ray Photoelectron. Upon exposure to NO gas, a chemical shift of Fe+3 and appearance of new N peak was observed due to the electron transfer from NO ligand to Fe ion with the attachment of nitrosyl group to FeCTPP. This modification brings the functionality to the membrane for being used in biological systems such as membrane bioreactor material in biological NO removal technology.

  16. Sensitive Method for Biomolecule Detection Utilizing Signal Amplification with Porphyrin Nanoparticles.

    PubMed

    Gibson, Lauren E; Wright, David W

    2016-06-07

    Disease diagnosis requires identification of biomarkers that occur in small quantities, making detection a difficult task. Effective diagnosis is an even greater challenge in low-resource areas of the world. Methods must be simple, stable, and sensitive so that tests can be easily administered and withstand uncontrolled environmental conditions. One approach to this issue is development of stable signal amplification strategies. In this work, we applied the nanocrystal-based signal amplification method to tetra(4-carboxyphenyl)porphyrin nanoparticles (TCPP NPs). The dissolution of the nanoparticle into thousands of porphyrin molecules results in amplified detection of the biomarker. By using nanoparticles as the signal-generating moiety, stability of the detection method is increased relative to commonly used enzyme-based assays. Additionally, the inherent fluorescent signal of TCPP molecules can be measured after nanoparticle dissolution. The ability to directly read the TCPP fluorescent signal increases assay simplicity by reducing the steps required for the test. This detection method was optimized by detecting rabbit IgG and then was applied to the detection of the malarial biomarker Plasmodium falciparum histidine-rich protein II (pfHRPII) from a complex matrix. The results for both biomarkers were assays with low picomolar limits of detection.

  17. Cell death mechanistic study of photodynamic therapy against breast cancer cells utilizing liposomal delivery of 5,10,15,20-tetrakis(benzo[b]thiophene) porphyrin.

    PubMed

    Nam, Geewoo; Rangasamy, Sabarinathan; Ju, Hee; Samson, Annie Agnes Suganya; Song, Joon Myong

    2017-01-01

    5,10,15,20-Tetrakis(benzo[b]thiophene) porphyrin (BTP) is a newly synthesized hydrophobic photosensitizer with fluorescence quantum yield in toluene: ΦF=0.062. Previously, its limitations in solubility had hindered scientific experimentation regarding its photodynamic effects on cancer cells. By utilizing various compositions of liposomes in order to alter the solubility of BTP, the photocytotoxicity, reactive oxygen species generation, and subcellular localization of the liposomal BTP were identified in this work. DNA fragmentation and high content screening assays were performed in order to shed light on the tumoricidal mechanism of the liposomal photosensitizer. The MTT assay results showed promising results in the irradiation specific PDT activity against MCF-7 cells in all liposomal compositions. Production of ROS was confirmed in the liposomal BTP treated MCF-7 cells after irradiation in a concentration dependent manner. The subcellular localization assays revealed that the localization of BTP was dependent on both the photosensitizer's chemical properties and the properties of the delivery agent encapsulating aforesaid substance. Significant DNA fragmentation was observed in both nucleus localizing liposomal BTP, BTP encapsulated DOPC and DOPE (DOPC-BTP and DOPE-BTP), treated MCF-7 cells. All liposomal-BTPs were successful in inducing mitochondrial permeability transition, an increase in the permeability of the mitochondrial membrane, and activating caspase-3/7. ER localizing BTP were able to significantly increase the cytosolic calcium levels by photodynamic therapy, confirming the photodynamic ability of ER localized BTP to damage the ER membrane. The application of liposomes in delivering a novel hydrophobic photosensitizer, BTP, and photodynamic therapy treatment against MCF-7 cells were successful. It was confirmed that the MCF-7 cell death pathway via photodynamic therapy was altered in a controlled manner by controlling the intracellular localization

  18. Porphyrin-loaded liposomes and graphene oxide used for the membrane pore-forming protein assay and inhibitor screening.

    PubMed

    Liu, Zhongde; Long, Tengfei; Wu, Shuang; Li, Chong

    2015-08-21

    The interaction of planar aromatic molecules with the graphene oxide (GO) sheets is often marked by the fluorescence quenching of the former. Here, the α,β,γ,δ-tetrakis[4-(trimethylammoniumyl)phenyl]porphyrin (TAPP) molecules and the GO, corresponding to the energy donor and the acceptor respectively, are initially separated by encapsulating the TAPP molecules within the liposomes, to obstruct the formation of the self-assembled energy transfer-based quenching system. Upon disruption of the liposome membranes by the PLA2 or the α-toxin, the encapsulated TAPP molecules are released and subsequently result in significant fluorescence changes. Thus, a platform based on the fluorescence signal for monitoring the activity of the membrane pore-forming protein with advantages of high sensitivity and commonality was established. Using this strategy, we can detect the PLA2 and the α-toxin concentrations as low as 200 pM and 9.0 nM, respectively. Furthermore, by taking chlorpromazine and baicalin as the examples, we use the assay to evaluate the prohibition effects on the PLA2 and the α-toxin, and the IC50 values of chlorpromazine toward the PLA2 (9.6 nM) and that of baicalin toward the α-toxin (289.2 nM) were found to be 12.0 ± 0.62 μM and 26.9 ± 2.6 μM, respectively.

  19. Porphyrin-sensitized solar cells.

    PubMed

    Li, Lu-Lin; Diau, Eric Wei-Guang

    2013-01-07

    Nature has chosen chlorophylls in plants as antennae to harvest light for the conversion of solar energy in complicated photosynthetic processes. Inspired by natural photosynthesis, scientists utilized artificial chlorophylls - the porphyrins - as efficient centres to harvest light for solar cells sensitized with a porphyrin (PSSC). After the first example appeared in 1993 of a porphyrin of type copper chlorophyll as a photosensitizer for PSSC that achieved a power conversion efficiency of 2.6%, no significant advance of PSSC was reported until 2005; beta-linked zinc porphyrins were then reported to show promising device performances with a benchmark efficiency of 7.1% reported in 2007. Meso-linked zinc porphyrin sensitizers in the first series with a push-pull framework appeared in 2009; the best cell performed comparably to that of a N3-based device, and a benchmark 11% was reported for a porphyrin sensitizer of this type in 2010. With a structural design involving long alkoxyl chains to envelop the porphyrin core to suppress the dye aggregation for a push-pull zinc porphyrin, the PSSC achieved a record 12.3% in 2011 with co-sensitization of an organic dye and a cobalt-based electrolyte. The best PSSC system exhibited a panchromatic feature for light harvesting covering the visible spectral region to 700 nm, giving opportunities to many other porphyrins, such as fused and dimeric porphyrins, with near-infrared absorption spectral features, together with the approach of molecular co-sensitization, to enhance the device performance of PSSC. According to this historical trend for the development of prospective porphyrin sensitizers used in PSSC, we review systematically the progress of porphyrins of varied kinds, and their derivatives, applied in PSSC with a focus on reports during 2007-2012 from the point of view of molecular design correlated with photovoltaic performance.

  20. Porphyrin Tests

    MedlinePlus

    ... Table adapted from: "Iron and porphyrin metabolism," Clinical Chemistry: Theory, Analysis and Correlation , courtesy of William E. ... Health Professionals ©2001 - by American Association for Clinical Chemistry • Contact Us | Terms of Use | Privacy We comply ...

  1. Efficient Photocurrent Enhancement from Porphyrin Molecules on Plasmonic Copper Arrays: Beneficial Utilization of Copper Nanoanntenae on Plasmonic Photoelectric Conversion Systems.

    PubMed

    Sugawa, Kosuke; Yamaguchi, Daisuke; Tsunenari, Natsumi; Uchida, Koji; Tahara, Hironobu; Takeda, Hideyuki; Tokuda, Kyo; Jin, Shota; Kusaka, Yasuyuki; Fukuda, Nobuko; Ushijima, Hirobumi; Akiyama, Tsuyoshi; Watanuki, Yasuhiro; Nishimiya, Nobuyuki; Otsuki, Joe; Yamada, Sunao

    2017-01-11

    We demonstrated the usefulness of Cu light-harvesting plasmonic nanoantennae for the development of inexpensive and efficient artificial organic photoelectric conversion systems. The systems consisted of the stacked structures of layers of porphyrin as a dye molecule, oxidation-suppressing layers, and plasmonic Cu arrayed electrodes. To accurately evaluate the effect of Cu nanoantenna on the porphyrin photocurrent, the production of Cu2O by the spontaneous oxidation of the electrode surfaces, which can act as a photoexcited species under visible light irradiation, was effectively suppressed by inserting the ultrathin linking layers consisting of 16-mercaptohexadecanoic acid, titanium oxide, and poly(vinyl alcohol) between the electrode surface and porphyrin molecules. The reflection spectra in an aqueous environment of the arrayed electrodes, which were prepared by thermally depositing Cu on two-dimensional colloidal crystals of silica with diameters of 160, 260, and 330 nm, showed clear reflection dips at 596, 703, and 762 nm, respectively, which are attributed to the excitation of localized surface plasmon resonance (LSPR). While the first dip lies within the wavelengths where the imaginary part of the Cu dielectric function is moderately large, the latter two dips lie within a region of a quite small imaginary part. Consequently, the LSPR excited at the red region provided a particularly large enhancement of porphyrin photocurrent at the Q-band (ca. 59-fold), compared to that on a Cu planar electrode. These results strongly suggest that the plasmonic Cu nanoantennae contribute to the substantial improvement of photoelectric conversion efficiency at the wavelengths, where the imaginary part of the dielectric function is small.

  2. Porous membrane utilization in plant nutrient delivery

    NASA Technical Reports Server (NTRS)

    Dreschel, T. W.; Hinkle, C. R.; Prince, R. P.; Knott, W. M., III

    1987-01-01

    A spacecraft hydroponic plant growth unit of tubular configuration, employing a microporous membrane as a capilary interface between plant roots and a nutrient solution, is presented. All three of the experimental trials undertaken successfully grew wheat from seed to harvest. Attention is given to the mass/seed, number of seeds/head, ratio of seed dry mass to total plant dry mass, production of tillers, and mass of seed/plant. Dry matter production is found to be reduced with increasing suction pressure; this is true for both average seed and average total dry matter/plant. This may be due to a reduction in water and nutrient availability through the microporous membrane.

  3. Porous membrane utilization in plant nutrient delivery

    NASA Technical Reports Server (NTRS)

    Dreschel, T. W.; Hinkle, C. R.; Prince, R. P.; Knott, W. M., III

    1987-01-01

    A spacecraft hydroponic plant growth unit of tubular configuration, employing a microporous membrane as a capilary interface between plant roots and a nutrient solution, is presented. All three of the experimental trials undertaken successfully grew wheat from seed to harvest. Attention is given to the mass/seed, number of seeds/head, ratio of seed dry mass to total plant dry mass, production of tillers, and mass of seed/plant. Dry matter production is found to be reduced with increasing suction pressure; this is true for both average seed and average total dry matter/plant. This may be due to a reduction in water and nutrient availability through the microporous membrane.

  4. Scalable antifouling reverse osmosis membranes utilizing perfluorophenyl azide photochemistry.

    PubMed

    McVerry, Brian T; Wong, Mavis C Y; Marsh, Kristofer L; Temple, James A T; Marambio-Jones, Catalina; Hoek, Eric M V; Kaner, Richard B

    2014-09-01

    We present a method to produce anti-fouling reverse osmosis (RO) membranes that maintains the process and scalability of current RO membrane manufacturing. Utilizing perfluorophenyl azide (PFPA) photochemistry, commercial reverse osmosis membranes were dipped into an aqueous solution containing PFPA-terminated poly(ethyleneglycol) species and then exposed to ultraviolet light under ambient conditions, a process that can easily be adapted to a roll-to-roll process. Successful covalent modification of commercial reverse osmosis membranes was confirmed with attenuated total reflectance infrared spectroscopy and contact angle measurements. By employing X-ray photoelectron spectroscopy, it was determined that PFPAs undergo UV-generated nitrene addition and bind to the membrane through an aziridine linkage. After modification with the PFPA-PEG derivatives, the reverse osmosis membranes exhibit high fouling-resistance. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Porphyrin Microparticles for Biological and Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Huynh, Elizabeth

    Lipids are one of the critical building blocks of life, forming the plasma membrane of cells. In addition, porphyrins also play an equally important role in life, for example, through carrying oxygen in blood. The importance of both these components is evident through the biological and biomedical applications of supramolecular structures generated from lipids and porphyrins. This thesis investigates new porphyrin microparticles based on porphyrin-lipid architecture and their potential applications in biology and medicine. In Chapter 1, a background on lipid and porphyrin-based supramolecular structures is presented and design considerations for generating multifunctional agents. Chapter 2 describes the generation of a monolayer porphyrin microparticle as a dual-modal ultrasound and photoacoustic contrast agent and subsequently, a trimodal ultrasound, photoacoustic and fluorescence contrast agent. Chapter 3 examines the optical and morphological response of these multimodality ultrasound-based contrast agents to low frequency, high duty cycle ultrasound that causes the porphyrin microparticles to convertinto nanoparticles. Chapter 4 examines the generation of bilayer micrometer-sized porphyrin vesicles and their properties. Chapter 5 presents a brief summary and potential future directions. Although these microscale structures are similar in structure, the applications of these structures greatly differ with potential applications in biology and also imaging and therapy of disease. This thesis aims to explore and demonstrate the potential of new simplified, supramolecular structures based on one main building block, porphyrin-lipid.

  6. Drop-Coating Deposition Raman (DCDR) Spectroscopy as a Tool for Membrane Interaction Studies: Liposome-Porphyrin Complex.

    PubMed

    Kočišová, Eva; Procházka, Marek; Vaculčiaková, Lenka

    2015-08-01

    Drop-coating deposition Raman (DCDR) spectroscopy is based on the measurement of a sample that has been preconcentrated by being dried on a special hydrophobic plate. In addition to its higher sensitivity, the advantage of DCDR over the conventional Raman spectroscopy is the small sample volume needed, the lack of interference from solvents, and the capability of segregating any impurities present and separating components in more complex samples. In this study, DCDR spectroscopy was employed to investigate the complex of the cationic copper(II) 5,10,15,20-tetrakis(1-methyl-4-pyridyl) porphyrin (CuTMPyP) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes. Drop-coating deposition Raman spectra were treated using factor analysis (FA), which led to the following conclusions: (i) the distribution of CuTMPyP in the complex is not homogenous, (ii) the DCDR technique segregates complexed and noncomplexed parts of the sample, (iii) the spectral changes caused by the drying process and by the interaction of CuTMPyP with the DPPC liposomes can be distinguished, and (iv) the porphyrin molecules interacting with DPPC affect both the order-disorder properties of the lipid chains and the lipid head.

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

    NASA Astrophysics Data System (ADS)

    Ng, Kenneth Ka-Seng

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

  8. The Arabidopsis Multistress Regulator TSPO Is a Heme Binding Membrane Protein and a Potential Scavenger of Porphyrins via an Autophagy-Dependent Degradation Mechanism[W][OA

    PubMed Central

    Vanhee, Celine; Zapotoczny, Grzegorz; Masquelier, Danièle; Ghislain, Michel; Batoko, Henri

    2011-01-01

    TSPO, a stress-induced, posttranslationally regulated, early secretory pathway-localized plant cell membrane protein, belongs to the TspO/MBR family of regulatory proteins, which can bind porphyrins. This work finds that boosting tetrapyrrole biosynthesis enhanced TSPO degradation in Arabidopsis thaliana and that TSPO could bind heme in vitro and in vivo. This binding required the His residue at position 91 (H91), but not that at position 115 (H115). The H91A and double H91A/H115A substitutions stabilized TSPO and rendered the protein insensitive to heme-regulated degradation, suggesting that heme binding regulates At-TSPO degradation. TSPO degradation was inhibited in the autophagy-defective atg5 mutant and was sensitive to inhibitors of type III phosphoinositide 3-kinases, which regulate autophagy in eukaryotic cells. Mutation of the two Tyr residues in a putative ubiquitin-like ATG8 interacting motif of At-TSPO did not affect heme binding in vitro but stabilized the protein in vivo, suggesting that downregulation of At-TSPO requires an active autophagy pathway, in addition to heme. Abscisic acid–dependent TSPO induction was accompanied by an increase in unbound heme levels, and downregulation of TSPO coincided with the return to steady state levels of unbound heme, suggesting that a physiological consequence of active TSPO downregulation may be heme scavenging. In addition, overexpression of TSPO attenuated aminolevulinic acid–induced porphyria in plant cells. Taken together, these data support a role for TSPO in porphyrin binding and scavenging during stress in plants. PMID:21317376

  9. Development of a novel fluorimetric bulk optode membrane based on meso-tetrakis(2-hydroxynaphthyl) porphyrin (MTHNP) for highly sensitive and selective monitoring of trace amounts of Hg2+ ions.

    PubMed

    Shamsipur, Mojtaba; Sadeghi, Marzieh; Beyzavi, Mohammad Hassan; Sharghi, Hashem

    2015-03-01

    The fluorescence spectra and response characteristics of two porphyrin compounds meso-tetrakis(2-hydroxynaphthyl) porphyrin and meso-tetra (2-thiophene) porphyrin (MTHNP) to Hg(2+) were investigated. MTHNP showed preferable fluorescence response to Hg(2+). Thereby, an efficient and selective fluorimetric optode membrane based on the fluorescence quenching of MTHNP for Hg(2+) ion determination at low concentration levels has been developed. The sensing membrane containing MTHNP reversibly responded to Hg(2+) with a working concentration range covering from 5.0×10(-9) to 1.25×10(-5)M with a relatively fast response time less than 3min. In addition to high stability, reversibility and reproducibility, the sensor showed extremely high selectivity toward Hg(2+) ion with respect to some alkali, alkaline earth and heavy metal ions. The limit of detection for Hg(2+) was 5.0×10(-9)M. The proposed fluorescent sensor was successfully applied to the direct determination of mercury content of biofenac eye drop, hair and different water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Controlled targeting of different subcellular sites by porphyrins in tumour-bearing mice.

    PubMed

    Jori, G; Reddi, E; Cozzani, I; Tomio, L

    1986-05-01

    Unilamellar liposomes of dipalmitoyl-phosphatidylcholine can incorporate various porphyrins in either the phospholipid bilayer or the internal aqueous compartment depending on the water-/lipo-solubility of the drug. Intraperitoneal injection of the liposome-bound porphyrins to mice bearing a MS-2 fibrosarcoma results in remarkably more efficient tumour targeting than that obtained by administration of the same porphyrins dissolved in homogeneous aqueous solution. Moreover, also water-insoluble porphyrins can be transported to the tumour via liposomes. Fractionation of liver and neoplastic cells indicates that the subcellular distribution of liposome-delivered porphyrins is also dependent on their solubility properties: thus, relatively polar porphyrins, such as tetra(4-sulfonatophenyl)porphine and uroporphyrin, are mainly recovered from the soluble fraction, whereas hydrophobic porphyrins, such as haematoporphyrin or porphyrin esters, preferentially partition in the cytoplasmic membrane. As a consequence, different subcellular sites can be targeted by porphyrins and possibly photodamaged through a suitable choice of the drug-carrier system.

  11. In-situ utilization of generated electricity in an electrochemical membrane bioreactor to mitigate membrane fouling.

    PubMed

    Wang, Yun-Kun; Li, Wen-Wei; Sheng, Guo-Ping; Shi, Bing-Jing; Yu, Han-Qing

    2013-10-01

    How to mitigate membrane fouling remains a critical challenge for widespread application of membrane bioreactors. Herein, an antifouling electrochemical membrane bioreactor (EMBR) was developed based on in-situ utilization of the generated electricity for fouling control. In this system, a maximum power density of 1.43 W/m(3) and a current density of 18.49 A/m(3) were obtained. The results demonstrate that the formed electric field reduced the deposition of sludge on membrane surface by enhancing the electrostatic repulsive force between them. The produced H2O2 at the cathode also contributed to the fouling mitigation by in-situ removing the membrane foulants. In addition, 93.7% chemical oxygen demand (COD) removal and 96.5% NH4(+)-N removal in average as well as a low effluent turbidity of below 2 NTU were achieved, indicating a good wastewater treatment performance of the EMBR. This work provides a proof-of-concept study of an antifouling MBR with high wastewater treatment efficiency and electricity recovery, and implies that electrochemical control might provide another promising avenue to in-situ suppress the membrane fouling in MBRs.

  12. A Porphyrin-PEG Polymer with Rapid Renal Clearance

    PubMed Central

    Huang, Haoyuan; Hernandez, Reinier; Geng, Jumin; Sun, Haotian; Song, Wentao; Chen, Feng; Graves, Stephen A; Nickles, Robert J.; Cheng, Chong; Cai, Weibo; Lovell, Jonathan F.

    2015-01-01

    Tetracarboxylic porphyrins and polyethylene glycol (PEG) diamines were crosslinked in conditions that gave rise to a water-soluble porphyrin polyamide. Using PEG linkers 2 kDa or larger prevented fluorescence self-quenching. This networked porphyrin mesh was retained during dialysis with membranes with a 100 kDa pore size, yet passed through the membrane when centrifugal filtration was applied. Following intravenous administration, the porphyrin mesh, but not the free porphyrin, was rapidly cleared via renal excretion. The process could be monitored by fluorescence analysis of collected urine, with minimal background due to the large Stokes shift of the porphyrin (230 nm separating excitation and emission peaks). In a rhabdomyolysis mouse model of renal failure, porphyrin mesh urinary clearance was significantly impaired. This led to slower accumulation in the bladder, which could be visualized non-invasively via fluorescence imaging. Without further modification, the porphyrin mesh was chelated with 64Cu for dynamic whole body positron emission tomography imaging of renal clearance. Together, these data show that small porphyrin-PEG polymers can serve as effective multimodal markers of renal function. PMID:26517562

  13. Porphyrin-Based Photocatalytic Lithography

    PubMed Central

    Bearinger, Jane P.; Stone, Gary; Christian, Allen T.; Dugan, Lawrence; Hiddessen, Amy L.; Wu, Kuang Jen J.; Wu, Ligang; Hamilton, Julie; Stockton, Cheryl; Hubbell, Jeffrey A.

    2008-01-01

    Photocatalytic lithography couples light with photoreactive coated mask materials to pattern surface chemistry. We excite porphyrins to create radical species that photocatalytically oxidize, and thereby pattern, chemistries in the local vicinity. The technique advantageously is suited for use with a wide variety of substrates. It is fast and robust, and the wavelength of light does not limit the resolution of patterned features. We have patterned proteins and cells to demonstrate the utility of photocatalytic lithography in life science applications. PMID:18380510

  14. Synthesis of porphyrin nanostructures

    DOEpatents

    Fan, Hongyou; Bai, Feng

    2014-10-28

    The present disclosure generally relates to self-assembly methods for generating porphyrin nanostructures. For example, in one embodiment a method is provided that includes preparing a porphyrin solution and a surfactant solution. The porphyrin solution is then mixed with the surfactant solution at a concentration sufficient for confinement of the porphyrin molecules by the surfactant molecules. In some embodiments, the concentration of the surfactant is at or above its critical micelle concentration (CMC), which allows the surfactant to template the growth of the nanostructure over time. The size and morphology of the nanostructures may be affected by the type of porphyrin molecules used, the type of surfactant used, the concentration of the porphyrin and surfactant the pH of the mixture of the solutions, and the order of adding the reagents to the mixture, to name a few variables.

  15. Conformation and electronic population transfer in membrane-supported self-assembled porphyrin dimers by 2D fluorescence spectroscopy.

    PubMed

    Perdomo-Ortiz, Alejandro; Widom, Julia R; Lott, Geoffrey A; Aspuru-Guzik, Alán; Marcus, Andrew H

    2012-09-06

    Two-dimensional fluorescence spectroscopy (2D FS) is applied to determine the conformation and femtosecond electronic population transfer in a dimer of magnesium meso tetraphenylporphyrin. The dimers are prepared by self-assembly of the monomer within the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine liposomes. A theoretical framework to describe 2D FS experiments is presented, and a direct comparison is made between the observables of this measurement and those of 2D electronic spectroscopy (2D ES). The sensitivity of the method to varying dimer conformation is explored. A global multivariable fitting analysis of linear and 2D FS data indicates that the dimer adopts a "bent T-shaped" conformation. Moreover, the manifold of singly excited excitons undergoes rapid electronic dephasing and downhill population transfer on the time scale of ∼95 fs. The open conformation of the dimer suggests that its self-assembly is favored by an increase in entropy of the local membrane environment.

  16. Utilization of bipolar membrane electrodialysis for salt water treatment.

    PubMed

    Venugopal, Krishnaveni; Dharmalingam, Sangeetha

    2013-07-01

    Bipolar ion-exchange membranes, using polystyrene ethylene utylenes polystyrene (PSEBS) with polyvinyl alcohol as the intermediate, were fabricated and evaluated for their potential to remove secondary salts from lab-prepared salt solutions. Experiments were carried out in batch re-circulation mode. The mechanical properties and microscopic images of the membranes were analyzed before, during, and after the electrodialysis process. The performance of the membranes in the stack was evaluated in terms of energy consumption and current efficiency, and found to be 1.07 Wh/mol and 0.67, respectively. Commercially-produced membranes were used as a comparison to the PSEBS-based membranes. In the case of the commercial membrane, polystyrene divinylbenzene, the values for the above parameters were observed to be 2.59 Wh/mol and 0.63, respectively. In addition, other parameters, such as transport number of ions and acid - alkali production, were evaluated for both PSEBS-based and commercially-produced membranes. Results indicated that PSEBS-based membranes exhibited better performance than the commercial membranes.

  17. Utilization of membranes for H2O recycle system

    NASA Technical Reports Server (NTRS)

    Ohya, H.; Oguchi, M.

    1986-01-01

    Conceptual studies of closed ecological life support systems (CELSS) carried out at NAL in Japan for a water recycle system using membranes are reviewed. The system will treat water from shower room, urine, impure condensation from gas recycle system, and so on. The H2O recycle system is composed of prefilter, ultrafiltration membrane, reverse osmosis membrane, and distillator. Some results are shown for a bullet train of toilet-flushing water recycle equipment with an ultraviltration membrane module. The constant value of the permeation rate with a 4.7 square meters of module is about 70 1/h after 500th of operation. Thermovaporization with porous polytetrafluorocarbon membrane is also proposed to replce the distillator.

  18. A planar dodecasubstituted porphyrin

    SciTech Connect

    Senge, M.O.; Medforth, C.J.; Smith, K.M. ); Sparks, L.D.; Shelnutt, J.A. )

    1993-04-28

    Structural investigations of copper and nickel complexes of dodecasubstituted porphyrins bearing aryl groups at the meso positions and propano rings at the pyrrole [beta] positions reveal considerable differences in their macrocycle conformations. While the nickel complex NiTC5T(3,4,5-OMeP)P was found to exhibit a nonplanar conformation which is considerably more planar than that of other dodecasubstituted porphyrins, the corresponding copper complex CuTC5T(3,4,5-OMeP)P was planar. CuTC5T(3,4,5-OMeP)P thus represents the first example of a completely planar dodecasubstituted porphyrin. The crystal structures of both porphyrins reveal that the C[sub b]-C[sub b]-CH[sub 2] angle is 13[degrees] smaller than in OEP derivatives. This change, which moves the methylene and aryl substituents further apart, effectively removes the steric repulsion responsible for the very nonplanar conformations observed for other dodecasubstituted porphyrins. Molecular mechanics calculations using a porphyrin force field correctly predict a planar macrocycle conformation. The possible reasons for the discrepancy between the observed moderately nonplanar structure and the calculated planar structure for NiTC5T(3,4,5-OMeP)P are discussed. The usefulness of spectroscopic probes (NMR, resonance Raman, electronic absorption) in predicting the planarity of dodecasubstituted porphyrins is also examined. The identification of a planar dodecasubstituted porphyrin further indicates the flexibility of the tetrapyrrole macrocycle and has implications for the study of nonplanarity in synthetic porphyrins and metallotetrapyrrole containing biomolecules. 32 refs., 6 figs., 7 tabs.

  19. Functionalized expanded porphyrins

    DOEpatents

    Sessler, Jonathan L; Pantos, Patricia J

    2013-11-12

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

  20. Soluble porphyrin polymers

    DOEpatents

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

    2015-07-07

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

  1. Porphyrin-based Photocatalytic Nanolithography

    SciTech Connect

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

    2009-06-08

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

  2. Porphyrin-Based Photocatalytic Lithography

    SciTech Connect

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

    2007-10-15

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

  3. A microfilter utilizing a polyethersulfone porous membrane with nanopores

    NASA Astrophysics Data System (ADS)

    Gu, Ye; Miki, Norihisa

    2007-11-01

    We present a novel microfilter system used for the selective separation of solutes of molecular sizes 1-2 nm. The microfilter system consists of two layers of micro chambers made of PDMS and one piece of porous membrane made of polyethersulfone (PES) using the wet-phase inversion method. The PES membrane at the center of the two micro chambers acts as a barrier to molecules larger than its pores. A novel method of bonding the PES membrane to PDMS surface was developed in the device fabrication, whereby diffusion in the microfilter was theoretically derived and applied in the filtering evaluation. The filtering capacity of this microfilter for molecules of molecular sizes from 0.3 nm to 6.6 nm was evaluated using solution samples of sodium chloride (NaCl) and fluorescein isothiocyanate (FITC) dextrans with molecular weights of 4k, 20k and 70k, respectively. The filtering experiments indicated that the optimal membrane used for the device was P2S2. This microfilter system with optimal PES membrane was believed to be capable of selective separation at a molecular size barrier of 1-2 nm and also believed to have the potential for use in portable hemodialysis systems.

  4. Synthetic Porphyrins and Metalloporphyrins

    DTIC Science & Technology

    1976-12-10

    last type of complexes to be considered are the sterically hindered macrocycles . Examples of this class of complexes exe the capped" or "crow henhe...group IV metalloporphyrins, phthalocyanines and correspond- log Ru"l and Reol complexes induce smaller shifts than the lanthanides (about 8 ppm vs 25...ROLE W1r ROLE wTr ROLE Wt * ~Synthe tic Porphyrins Synthetic lMetalloporphyrinsj tetrapyrrole macrocycles "Inatural" porphyrins * j meso

  5. Separation of certain carboxylic acids utilizing cation exchange membranes

    DOEpatents

    Chum, Helena L.; Sopher, David W.

    1984-01-01

    A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100.degree. C. and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.

  6. Separation of certain carboxylic acids utilizing cation exchange membranes

    DOEpatents

    Chum, H.L.; Sopher, D.W.

    1983-05-09

    A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100/sup 0/C and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.

  7. Photochemical solar energy conversion utilizing semiconductors localized in membrane-mimetic systems

    SciTech Connect

    Fendler, J.H.

    1991-08-31

    Extending the frontiers of colloidal photochemistry and colloidal electrochemistry to solar photochemistry research had been the main objective of this research. More specific objectives of this proposal include the examination of semiconductor-particle-mediated photoelectron transfer and photoelectric effects in different membrane mimetic systems. Emphasis had been placed on developing bilayer lipid membranes and Langmuir-Blodgett films as new membrane-mimetic systems, as well as on the characterization and utilization of these systems.

  8. Ultra-sensitive acoustic fiber sensors utilizing nano-membranes

    NASA Astrophysics Data System (ADS)

    Jo, Wonuk; Digonnet, M. J. F.

    2015-09-01

    A new, highly sensitive, compact fiber acoustic sensor is reported that implements a micro-fabricated silicon membrane with a π/2 phase step combined to a single-mode fiber to form a simple interferometric sensor head. Compared to high-sensitivity membrane-based fiber Fabry-Perot (FP) sensors, it has a similar pressure resolution, it operates over a much broad range of wavelengths (~+/-150 nm vs. ~+/-1 nm), and fabrication is simpler. A prototype is reported with an average minimum detectable pressure (MDP) as low as 5.4 μPa/√Hz (1-30 kHz), in agreement with a model. A state-of-the-art FP fiber sensor with an average MDP about twice as low is described for comparison.

  9. Role of environmental factors on the structure and spectroscopic response of 5'-DNA-porphyrin conjugates caused by changes in the porphyrin-porphyrin interactions.

    PubMed

    Mammana, Angela; Pescitelli, Gennaro; Asakawa, Tomohiro; Jockusch, Steffen; Petrovic, Ana G; Monaco, Regina R; Purrello, Roberto; Turro, Nicholas J; Nakanishi, Koji; Ellestad, George A; Balaz, Milan; Berova, Nina

    2009-11-09

    We have explored the utility, strength, and limitation of through-space exciton-coupled circular dichroism in determination of the secondary structure of optically active chromophoric nanoarrays using the example of end-capped porphyrin- and metalloporphyrin-oligodeoxynucleotide conjugates. We put special emphasis on the explanation of the origin and significance of the distinctive multiple bands in the CD spectra (trisignate and tetrasignate CD bands). Such CD profiles are often observed in chiral aggregates or multichromophoric arrays but have never before been studied in detail. We found that variation of temperature and ionic strength has a profound effect on the geometry of the porphyrin-DNA conjugates and thus the nature of electronic interactions. At lower temperatures and in the absence of NaCl all three 5'-DNA-porphyrin conjugates display negative bisignate CD exciton couplets of variable intensity in the Soret region resulting from through-space interaction between the electric transition dipole moments of the two end-capped porphyrins. As the temperature is raised these exciton couplets are transformed into single positive bands originating from the porphyrin-single-strand DNA interactions. At higher ionic strengths and low temperatures, multisignate CD bands are observed in the porphyrin Soret region. These CD signature bands originate from a combination of intermolecular, end-to-end porphyrin-porphyrin stacking between duplexes and porphyrin-DNA interactions. The intermolecular aggregation was confirmed by fluorescence and absorption spectroscopy and resonance light scattering. DeVoe theoretical CD calculations, in conjunction with molecular dynamics simulations and Monte Carlo conformational searches, were used to mimic the observed bisignate exciton-coupled CD spectra as well as multiple CD bands. Calculations correctly predicted the sign and shape of the experimentally observed CD spectra. These studies reveal that the exciton-coupled circular

  10. Molecular catalysis of the oxygen reduction reaction by iron porphyrin catalysts tethered into Nafion layers: An electrochemical study in solution and a membrane-electrode-assembly study in fuel cells

    NASA Astrophysics Data System (ADS)

    He, Qinggang; Mugadza, Tawanda; Kang, Xiongwu; Zhu, Xiaobing; Chen, Shaowei; Kerr, John; Nyokong, Tebello

    2012-10-01

    This study was motivated by the need for improved understanding of the kinetics and transport phenomena in a homogeneous catalyst system for the oxygen reduction reaction (ORR). Direct interaction between the sulfonic groups of Nafion and an Fe(III) meso-tetra(N-methyl-4-pyridyl) porphine chloride (Fe(III)TMPyP) compound was observed using FTIR and in situ UV-Vis spectroelectrochemical characterizations. A positive shift of the half wave potential value (E1/2) for ORR on the iron porphyrin catalyst (Fe(III)TMPyP) was observed upon addition of a specific quantity of Nafion ionomer on a glassy carbon working electrode, indicating not only a faster charge transfer rate but also the role of protonation in the oxygen reduction reaction (ORR) process. A membrane electrode assembly (MEA) was made as a sandwich of a Pt-coated anode, a Nafion® 212 membrane, and a Fe(III)TMPyP + Nafion ionomer-coated cathode. This three-dimensional catalysis system has been demonstrated to be working in a H2/O2 proton exchange membrane (PEM) fuel cell test.

  11. Kinetic studies of porphyrin distribution in suspensions of tumor cells

    NASA Astrophysics Data System (ADS)

    Zorin, Vladimir P.; Mel'nov, Sergey B.; Savitsky, Valery P.; Zorina, Tatyana E.

    1996-12-01

    Using a fluorescence activated cell sorting, we investigated the dynamics of porphyrins in suspensions of tumor cells. In addition to direct studies of the incorporation and output of several porphyrins (hematoporphyrin, hematoporphyrin dimethyl ester, chlorin e6 and its mono-, di-, trimethyl esters) from cells, their transfer between cells was investigated. It was shown that the rate of pigment accumulation by cells correlated with the rate of porphyrin penetration across the plasma membrane. As a result, apolar chlorins and HpDME displayed enhanced staining capacity which was independent on the integrity of plasma membrane of cells. To estimate the rate of pigment redistribution between cells, the suspension of tumor cells loaded with porphyrin had been mixed with unloaded cells and the distribution of all cells according to porphyrin fluorescence was determined in different intervals of time. It was obtained that the highest rate of the pigment transfer between cells was exhibited in the case of moderately apolar pigment. Porphyrins with dominantly hydrophobic and hydrophilic properties had a decreased capacity to intercellular migration. The results of this study indicate that, depending on the photosensitizer used, the processes of its distribution in the bulk of tumor tissue mediated by intercellular exchange may occur with a different rate.

  12. Electrically conducting porphyrin and porphyrin-fullerene electropolymers

    DOEpatents

    Gust, Jr., John Devens; Liddell, Paul Anthony; Gervaldo, Miguel Andres; Bridgewater, James Ward; Brennan, Bradley James; Moore, Thomas Andrew; Moore, Ana Lorenzelli

    2014-03-11

    Compounds with aryl ring(s) at porphyrin meso position(s) bearing an amino group in position 4 relative to the porphyrin macrocycle, and at least one unsubstituted 5 (hydrogen-bearing) meso position with the 10-, 15-, and/or 20-relationship to the aryl ring bearing the amino group, and metal complexes thereof, feature broad spectral absorption throughout the visible region. These compounds are electropolymerized to form electrically conducting porphyrin and porphyrin-fullerene polymers that are useful in photovoltaic applications. The structure of one such electrically conducting porphyrin polymer is shown below. ##STR00001##

  13. Porphyrins, porphyrin metabolism and porphyrias. I. Update.

    PubMed

    Thunell, S

    2000-11-01

    The biosynthesis of porphyrins is one of the most conserved parthways known, about the same sequence of reactions taking place in all species. By associating different metals, porphyrins give rise to the "pigments of life": chlorophyll, haem and cobalamin. The unique tetrapyrrolic structure enables it to function in an array of reactions as a single electron carrier and as a catalyst for redox reactions. In this capacity, it constitutes the prosthetic group of enzymes participating in cellular respiration, in conversion reactions involving steroids and lipophilic xenobiotics, in protective mechanisms directed against oxidative stress and in pathways providing central messenger molecules. The formation of haem is accomplished by a sequence of eight dedicated enzymes encoded by different genes, some being active in ubiquitous as well as in erythroid isoforms. Large differences between the participating enzymes with regard to catalytic power, with low capacity steps positioned early in the catalytic chain, constitute a bar against substrate overloading of enzymes processing porphyrins, thus preventing accumulation in the body of these phototoxic compounds under physiological conditions. Most of the haem in the body is produced by the liver and bone marrow, but the mechanisms applied for the control of the synthesis differ between the two organs. The extremely potent hemeprotein enzymes formed in the liver are rapidly turned over in response to current metabolic needs. They have half-lives in the order of minutes or hours and are restored by fast-acting mechanisms for the de novo synthesis, when needed. Uninterrupted and instant availability of the compound is secured by acute deinhibition of the initial enzyme of the synthetic chain, ubiquitous 5-aminolevulinate synthase (ALAS-1), in response to drain of the free cellular haem pool caused by prevailing demands for hemeproteins or by increased catabolism of the compound. In contrast, in the erythroid progenitor cell

  14. Mercury removal from aqueous streams utilizing microemulsion liquid membranes

    SciTech Connect

    Larson, K.A.; Wiencek, J.M.

    1994-11-01

    The goal of this work is the removal of mercury ion from wastewater using thermodynamically stable microemulsions as liquid membranes. The research focuses on identification and modeling of the appropriate aqueous and organic phase equilibrium reactions for mercury extraction and stripping, comparison of extraction kinetics between coarse emulsions and microemulsions, and demulsification and recovery of the emulsion components. An oleic acid microemulsion liquid membrane (water-in-oil) containing sulfuric acid as the internal phase reduces the feed phase mercury concentration from 460 mg/l to 0.84 mg/l in a single contacting. This compares favorably with a control extraction (oleic acid/no internal phase) which results in a final concentration of 20 mg/l Hg{sup +2}. Microemulsions can be demulsified using butanol as an additive. The demulsification kinetics are proportional to butanol concentration and temperature and inversely proportional to surfactant concentration. The demulsification rate is second order with respect to water concentration which implies that the rate-limiting step in the process is the rate of internal phase droplet encounters. Proof-of-principle experiments demonstrate the ability to extract mercury ion using microemulsions formulated with recycled organic phase, albeit at a somewhat reduced efficiency. The reduced efficiency is attributed to increased internal phase leakage due to residual butanol in the oil phase. Finally, the cycle is brought around full circle by recovering metallic mercury from the internal phase by electroplating. 27 refs., 11 figs., 1 tab.

  15. Circulating polymerase chain reaction chips utilizing multiple-membrane activation

    NASA Astrophysics Data System (ADS)

    Wang, Chih-Hao; Chen, Yi-Yu; Liao, Chia-Sheng; Hsieh, Tsung-Min; Luo, Ching-Hsing; Wu, Jiunn-Jong; Lee, Huei-Huang; Lee, Gwo-Bin

    2007-02-01

    This paper reports a new micromachined, circulating, polymerase chain reaction (PCR) chip for nucleic acid amplification. The PCR chip is comprised of a microthermal control module and a polydimethylsiloxane (PDMS)-based microfluidic control module. The microthermal control modules are formed with three individual heating and temperature-sensing sections, each modulating a specific set temperature for denaturation, annealing and extension processes, respectively. Micro-pneumatic valves and multiple-membrane activations are used to form the microfluidic control module to transport sample fluids through three reaction regions. Compared with other PCR chips, the new chip is more compact in size, requires less time for heating and cooling processes, and has the capability to randomly adjust time ratios and cycle numbers depending on the PCR process. Experimental results showed that detection genes for two pathogens, Streptococcus pyogenes (S. pyogenes, 777 bps) and Streptococcus pneumoniae (S. pneumoniae, 273 bps), can be successfully amplified using the new circulating PCR chip. The minimum number of thermal cycles to amplify the DNA-based S. pyogenes for slab gel electrophoresis is 20 cycles with an initial concentration of 42.5 pg µl-1. Experimental data also revealed that a high reproducibility up to 98% could be achieved if the initial template concentration of the S. pyogenes was higher than 4 pg µl-1. The preliminary results of the current paper were presented at the 19th IEEE International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2006), Istanbul, Turkey, 22-26 January, 2006.

  16. Enhancing PDT drug delivery by enzymatic cleavage of porphyrin phosphates

    NASA Astrophysics Data System (ADS)

    Xu, Bing; Liang, Gaolin; Wang, Ling; Yang, Zhimou; Chan, Kalok; Chang, Chi K.

    2007-02-01

    A new anionic porphyrin-phosphate conjugate has been made as the substrate of phosphatase to evaluate its cellular-uptake and potential targeting on cancer cells, taking advantage of the over-expression of phosphatases associated with the development of cancers. The phosphate groups increase the hydrophilicity of porphyrin dityrosine phosphate and facilitate its formulation in aqueous solvent. Upon hydrolysis by phosphatase after cellular uptaking, the more hydrophobic porphyrin-dityrosine promises to give better cellular retention. Indeed, the phosphate conjugate displayed a much better PDT effect than that of the parent porphyrin at the same concentration (10 μM) and light dosage on HeLa cells, indicating the enzyme-cleavage reaction occurred in HeLa cells plays a role. Photosenzitizers utilizing enzyme-cleavage might be a promising approach for photodynamic therapy.

  17. Membrane Separator for Redox Flow Batteries that Utilize Anion Radical Mediators.

    SciTech Connect

    Delnick, Frank M.

    2014-10-01

    A Na + ion conducting polyethylene oxide membrane is developed for an organic electrolyte redox flow battery that utilizes anion radical mediators. To achieve high specific ionic conductivity, tetraethyleneglycol dimethylether (TEGDME) is used as a plasticizer to reduce crystallinity and increase the free volume of the gel film. This membrane is physically and chemically stable in TEGDME electrolyte that contains highly reactive biphenyl anion radical mediators.

  18. Self-Registration Methods for Increasing Membrane Utilization within Compression-Sealed Microchannel Hemodialysers.

    PubMed

    Paul, Brian K; Porter, Spencer D

    2014-10-01

    More than 1.2 million people worldwide require regular hemodialysis therapy to treat end stage renal failure. Current hemodialysis systems are too expensive to support at-home hemodialysis where more frequent and longer duration treatment can lead to better patient outcomes. The key cost driver for hemodialysers is the cost of the hemodialysis membrane. Microchannel hemodialysers are smaller providing the potential to use significantly less membrane. Prior work has demonstrated the use of sealing bosses to form compression seals in microchannel hemodialysers. In this paper, estimates show that the percentage of the membrane utilized for mass transfer is highly dependent on the design and registration accuracy of adjacent blood and dialysate laminae. Efforts here focus on the development of a self-registration method to align polycarbonate laminae compatible with compression sealing schemes for membrane separation applications. Self-nesting registration methods were demonstrated with average registration accuracies of 11.4 ± 7.2 μm measured over a 50 mm scale. Analysis shows that the registration accuracy is constrained by tolerances in the embossing process. A dialysis test article was produced using the self-nesting registration method showing a measured average one-dimensional misregistration of 18.5 μm allowing a potential 41.4% of the membrane to be utilized for mass transfer when considering both microchannel and header regions. Mass transfer results provide evidence of a twofold to threefold increase in membrane utilization over other designs in the existing literature.

  19. Self-Registration Methods for Increasing Membrane Utilization within Compression-Sealed Microchannel Hemodialysers

    PubMed Central

    Paul, Brian K.; Porter, Spencer D.

    2015-01-01

    More than 1.2 million people worldwide require regular hemodialysis therapy to treat end stage renal failure. Current hemodialysis systems are too expensive to support at-home hemodialysis where more frequent and longer duration treatment can lead to better patient outcomes. The key cost driver for hemodialysers is the cost of the hemodialysis membrane. Microchannel hemodialysers are smaller providing the potential to use significantly less membrane. Prior work has demonstrated the use of sealing bosses to form compression seals in microchannel hemodialysers. In this paper, estimates show that the percentage of the membrane utilized for mass transfer is highly dependent on the design and registration accuracy of adjacent blood and dialysate laminae. Efforts here focus on the development of a self-registration method to align polycarbonate laminae compatible with compression sealing schemes for membrane separation applications. Self-nesting registration methods were demonstrated with average registration accuracies of 11.4 ± 7.2 μm measured over a 50 mm scale. Analysis shows that the registration accuracy is constrained by tolerances in the embossing process. A dialysis test article was produced using the self-nesting registration method showing a measured average one-dimensional misregistration of 18.5 μm allowing a potential 41.4% of the membrane to be utilized for mass transfer when considering both microchannel and header regions. Mass transfer results provide evidence of a twofold to threefold increase in membrane utilization over other designs in the existing literature. PMID:25642151

  20. A Convergent Coordination Chemistry-Based Approach to Dissymmetric Macrocyclic Cofacial Porphyrin Complexes

    SciTech Connect

    Oliveri, Christopher G.; Heo, Jungseok; Nguyen, SonBinh T.; Mirkin, Chad A.; Wawrzak, Zdzislaw

    2010-12-03

    We report a highly convergent and modular approach for the synthesis of dissymmetric cofacial porphyrin complexes, which is based upon the weak-link approach to supramolecular coordination chemistry. Specifically, we have utilized a halide-induced ligand rearrangement reaction, which is capable of providing heteroligated mixed-metal porphyrin complexes in quantitative yield. Significantly, the adoption of a coordination chemistry based approach for the synthesis of these complexes allows for facile in situ regulation of the porphyrin-porphyrin interactions through the addition of external chemical stimuli.

  1. Integrated Water Gas Shift Membrane Reactors Utilizing Novel, Non Precious Metal Mixed Matrix Membrane

    SciTech Connect

    Ferraris, John

    2013-09-30

    Nanoparticles of zeolitic imidazolate frameworks and other related hybrid materials were prepared by modifying published synthesis procedures by introducing bases, changing stoichiometric ratios, or adjusting reaction conditions. These materials were stable at temperatures >300 °C and were compatible with the polymer matrices used to prepare mixed- matrix membranes (MMMs). MMMs tested at 300 °C exhibited a >30 fold increase in permeability, compared to those measured at 35 °C, while maintaining H{sub 2}/CO{sub 2} selectivity. Measurements at high pressure (up to 30 atm) and high temperature (up to 300 °C) resulted in an increase in gas flux across the membrane with retention of selectivity. No variations in permeability were observed at high pressures at either 35 or 300 °C. CO{sub 2}-induced plasticization was not observed for Matrimid®, VTEC, and PBI polymers or their MMMs at 30 atm and 300 °C. Membrane surface modification by cross-linking with ethanol diamine resulted in an increase in H{sub 2}/CO{sub 2} selectivity at 35 °C. Spectrometric analysis showed that the cross-linking was effective to temperatures <150 °C. At higher temperatures, the cross-linked membranes exhibit a H{sub 2}/CO{sub 2} selectivity similar to the uncross-linked polymer. Performance of the polybenzimidazole (PBI) hollow fibers prepared at Santa Fe Science and Technology (SFST, Inc.) showed increased flux o to a flat PBI membrane. A water-gas shift reactor has been built and currently being optimized for testing under DOE conditions.

  2. Porphyrin analysis and coal rank. A porphyrin index of coalification

    SciTech Connect

    Bonnett, R.; Hughes, P.S. )

    1989-03-01

    The stable aromatic nature of the porphyrin nucleus might be expected to make biomarkers containing it excellent bases for the study of the maturation of sedimentary deposits. Thus the porphyrin macroring can be thought of as an inert carrier of information contained in eight or nine peripheral substituents the increased cracking of which would reveal increased maturation. For non-migrating fossil fuels such as lignite and coal, a relationship between the distribution of porphyrin molecular mass and coal rank would result. This idea is examined for a series of well characterized bituminous coals from the British Carboniferous. Extraction of porphyrins and metalloporphyrins is carried out with methanolic sulfuric acid, and the gallium porphyrin concentrates are analyzed both by HPLC and by mass spectrometry. A Porphyrin Index of Coalification (PIC Number) is derived and related to other maturity indices. Within the range of examples chosen it appears to provide a useful scientifically-based indicator of coal maturity.

  3. A novel sensor for monitoring of iron(III) ions based on porphyrins.

    PubMed

    Vlascici, Dana; Fagadar-Cosma, Eugenia; Popa, Iuliana; Chiriac, Vlad; Gil-Agusti, Mayte

    2012-01-01

    Three A(3)B porphyrins with mixed carboxy-, phenoxy-, pyridyl-, and dimethoxy-substituent functionalization on the meso-phenyl groups were obtained by multicomponent synthesis, fully characterized and used as ionophores for preparing PVC-based membrane sensors selective to iron(III). The membranes have an ionophore:PVC:plasticizer composition ratio of 1:33:66. Sodium tetraphenylborate was used as additive (20 mol% relative to ionophore). The performance characteristics (linear concentration range, slope and selectivity) of the sensors were investigated. The best results were obtained for the membrane based on 5-(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin plasticized with bis(2-ethylhexyl)sebacate, in a linear range from 1 × 10(-7)-1 × 10(-1) M with a slope of 21.6 mV/decade. The electrode showed high selectivity with respect to alkaline and heavy metal ions and a response time of 20 s. The influence of pH on the sensor response was studied. The sensor was used for a period of six weeks and the utility has been tested for the quantitative determination of Fe(III) in recovered solutions from spent lithium ion batteries and for the quantitative determination of Fe(III) in tap water samples.

  4. A Novel Sensor for Monitoring of Iron(III) Ions Based on Porphyrins

    PubMed Central

    Vlascici, Dana; Fagadar-Cosma, Eugenia; Popa, Iuliana; Chiriac, Vlad; Gil-Agusti, Mayte

    2012-01-01

    Three A3B porphyrins with mixed carboxy-, phenoxy-, pyridyl-, and dimethoxy-substituent functionalization on the meso-phenyl groups were obtained by multicomponent synthesis, fully characterized and used as ionophores for preparing PVC-based membrane sensors selective to iron(III). The membranes have an ionophore:PVC:plasticizer composition ratio of 1:33:66. Sodium tetraphenylborate was used as additive (20 mol% relative to ionophore). The performance characteristics (linear concentration range, slope and selectivity) of the sensors were investigated. The best results were obtained for the membrane based on 5-(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin plasticized with bis(2-ethylhexyl)sebacate, in a linear range from 1 × 10−7–1 × 10−1 M with a slope of 21.6 mV/decade. The electrode showed high selectivity with respect to alkaline and heavy metal ions and a response time of 20 s. The influence of pH on the sensor response was studied. The sensor was used for a period of six weeks and the utility has been tested for the quantitative determination of Fe(III) in recovered solutions from spent lithium ion batteries and for the quantitative determination of Fe(III) in tap water samples. PMID:22969395

  5. Membrane electrode assembly with enhanced platinum utilization for high temperature proton exchange membrane fuel cell prepared by catalyst coating membrane method

    NASA Astrophysics Data System (ADS)

    Liang, Huagen; Su, Huaneng; Pollet, Bruno G.; Linkov, Vladimir; Pasupathi, Sivakumar

    2014-11-01

    In this work, membrane electrode assemblies (MEAs) prepared by catalyst coating membrane (CCM) method are investigated for reduced platinum (Pt) loading and improved Pt utilization of high temperature proton exchange membrane fuel cell (PEMFC) based on phosphoric acid (PA)-doped poly(2,5-benzimidazole) (AB-PBI) membrane. The results show that CCM method exhibits significantly higher cell performance and Pt-specific power density than that of MEAs prepared with conventional gas diffusion electrode (GDE) under a low Pt loading level. In-suit cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) show that the MEAs prepared by the CCM method have a higher electrochemical surface area (ECSA), low cell ohmic resistance and low charge transfer resistance as compared to those prepared with GDEs at the same Pt loading.

  6. Highly non-planar dendritic porphyrin for pH sensing: observation of porphyrin monocation.

    PubMed

    Thyagarajan, Sujatha; Leiding, Thom; Arsköld, Sindra Peterson; Cheprakov, Andrei V; Vinogradov, Sergei A

    2010-11-01

    Metal-free porphyrin-dendrimers provide a convenient platform for the construction of membrane-impermeable ratiometric probes for pH measurements in compartmentalized biological systems. In all previously reported molecules, electrostatic stabilization (shielding) of the core porphyrin by peripheral negative charges (carboxylates) was required to shift the intrinsically low porphyrin protonation pK(a)'s into the physiological pH range (pH 6-8). However, binding of metal cations (e.g., K(+), Na(+), Ca(2+), Mg(2+)) by the carboxylate groups on the dendrimer could affect the protonation behavior of such probes in biological environments. Here we present a dendritic pH nanoprobe based on a highly non-planar tetraaryltetracyclohexenoporphyrin (Ar(4)TCHP), whose intrinsic protonation pK(a)'s are significantly higher than those of regular tetraarylporphyrins, thereby eliminating the need for electrostatic core shielding. The porphyrin was modified with eight Newkome-type dendrons and PEGylated at the periphery, rendering a neutral water-soluble probe (TCHpH), suitable for measurements in the physiological pH range. The protonation of TCHpH could be followed by absorption (e.g., ε(Soret)(dication)∼270,000 M(-1) cm(-1)) or by fluorescence. Unlike most tetraarylporphyrins, TCHpH is protonated in two distinct steps (pK(a)'s 7.8 and 6.0). In the region between the pK(a)'s, an intermediate species with a well-defined spectroscopic signature, presumably a TCHpH monocation, could be observed in the mixture. The performance of TCHpH was evaluated by pH gradient measurements in large unilamellar vesicles. The probe was retained inside the vesicles and did not pass through and/or interact with vesicle membranes, proving useful for quantification of proton transport across phospholipid bilayers. To interpret the protonation behavior of TCHpH we developed a model relating structural changes on the porphyrin macrocycle upon protonation to its basicity. The model was validated by

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

    SciTech Connect

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

    2016-10-01

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

  8. Porphyrins in photodynamic therapy - a search for ideal photosensitizers.

    PubMed

    Pushpan, S K; Venkatraman, S; Anand, V G; Sankar, J; Parmeswaran, D; Ganesan, S; Chandrashekar, T K

    2002-03-01

    The utility of light as a therapeutic agent can be traced back over thousands of years when it was used in Ancient Egypt, India and China to treat a variety of skin diseases like psoriasis, vitiligo, rickets, cancer and psychosis. The isolation of porphyrins and their inherent tumor localizing properties coupled with its ability to generate reactive singlet oxygen when activated by light of particular wavelength which in turn results in cytotoxicity led to the emergence of a new modality namely, photodynamic therapy (PDT) as a therapeutic tool. The higher degree of selectivity offered by this modality and fewer side effects when compared to chemotherapy and radiotherapy has prompted the researchers around the globe to generate new photosensitizers. Porphyrins and expanded porphyrins are one class of molecules under intense investigation due to their photosensitizing ability for PDT application. Expanded porphyrins result from the expansion of the phi electron conjugation by increasing the number of heterocyclic rings or bridging carbons of the existing porphyrin framework. These chromophores show strong absorptions in the red region (650-800 nm) compared to that of normal 18phi porphyrins. The strong absorption of light by a water soluble nontoxic photosensitizing molecule in the therapeutic window resulting in maximum penetration of light into the tissues coupled with high singlet oxygen production will conceptualize an ideal photosensitizer. This review highlights various porphyrinoid sensitizers reported till date and their photosensitizing ability both in vitro and in vivo studies. Furthermore, the urgent need for developing ideal photosensitizer for PDT will also be highlighted.

  9. Stacked antiaromatic porphyrins

    PubMed Central

    Nozawa, Ryo; Tanaka, Hiroko; Cha, Won-Young; Hong, Yongseok; Hisaki, Ichiro; Shimizu, Soji; Shin, Ji-Young; Kowalczyk, Tim; Irle, Stephan; Kim, Dongho; Shinokubo, Hiroshi

    2016-01-01

    Aromaticity is a key concept in organic chemistry. Even though this concept has already been theoretically extrapolated to three dimensions, it usually still remains restricted to planar molecules in organic chemistry textbooks. Stacking of antiaromatic π-systems has been proposed to induce three-dimensional aromaticity as a result of strong frontier orbital interactions. However, experimental evidence to support this prediction still remains elusive so far. Here we report that close stacking of antiaromatic porphyrins diminishes their inherent antiaromaticity in the solid state as well as in solution. The antiaromatic stacking furthermore allows a delocalization of the π-electrons, which enhances the two-photon absorption cross-section values of the antiaromatic porphyrins. This feature enables the dynamic switching of the non-linear optical properties by controlling the arrangement of antiaromatic π-systems on the basis of intermolecular orbital interactions. PMID:27901014

  10. Stacked antiaromatic porphyrins

    NASA Astrophysics Data System (ADS)

    Nozawa, Ryo; Tanaka, Hiroko; Cha, Won-Young; Hong, Yongseok; Hisaki, Ichiro; Shimizu, Soji; Shin, Ji-Young; Kowalczyk, Tim; Irle, Stephan; Kim, Dongho; Shinokubo, Hiroshi

    2016-11-01

    Aromaticity is a key concept in organic chemistry. Even though this concept has already been theoretically extrapolated to three dimensions, it usually still remains restricted to planar molecules in organic chemistry textbooks. Stacking of antiaromatic π-systems has been proposed to induce three-dimensional aromaticity as a result of strong frontier orbital interactions. However, experimental evidence to support this prediction still remains elusive so far. Here we report that close stacking of antiaromatic porphyrins diminishes their inherent antiaromaticity in the solid state as well as in solution. The antiaromatic stacking furthermore allows a delocalization of the π-electrons, which enhances the two-photon absorption cross-section values of the antiaromatic porphyrins. This feature enables the dynamic switching of the non-linear optical properties by controlling the arrangement of antiaromatic π-systems on the basis of intermolecular orbital interactions.

  11. Urinary porphyrin profiles as a biomarker of mercury exposure: Studies on dentists with occupational exposure to mercury vapor

    SciTech Connect

    Woods, J.S. Battelle Seattle Research Center, WA ); Martin, M.D. ); Naleway, C.A. ); Echeverria, D. )

    1993-01-01

    Porphyrins are formed as intermediates in the biosynthesis of heme. In humans and other mammals, porphyrins with eight, seven, six, five, and four carboxyl groups are excreted in the urine in a well-established pattern. Mercury selectively alters porphyrin metabolism in kidney proximal tubule cells, leading to an altered urinary porphyrin excretion pattern. Previous studies in rats have shown that changes in the urinary porphyrin profile during exposure to mercury as methylmercury hydroxide are uniquely characterized by highly elevated (20- to 30-fold) levels of four- and five-carboxyl porphyrins and by the excretion of an atypical porphyrin ([open quotes]precoproporphyrin[close quotes]), which elutes on high performance liquid chromatography (HPLC) approximately midway between penta- and coproporphyrins. Changes in the urinary porphyrin profile are highly correlated with the dose and duration of mercury exposure and persist for up to 20 wk following cessation of mercury treatment. In the present studies, the utility of urinary porphyrin profile changes as a biomarker of mercury exposure in human subjects was evaluated. Urinary porphyrin concentrations were measured in dentists participating in the Health Screening Programs conducted during the 1991 and 1992 annual meetings of the American Dental Association dentists with no detectable urinary mercury, mean concentrations of urinary porphyrins were within the established normal ranges for male human subjects. 23 refs., 3 figs., 5 tabs.

  12. Separation, Immobilization, and Biocatalytic Utilization of Proteins by a Supramolecular Membrane

    PubMed Central

    Krieg, Elisha; Albeck, Shira; Weissman, Haim; Shimoni, Eyal; Rybtchinski, Boris

    2013-01-01

    Membrane separation of biomolecules and their application in biocatalysis is becoming increasingly important for biotechnology, demanding the development of new biocompatible materials with novel properties. In the present study, an entirely noncovalent water-based material is used as a membrane for size-selective separation, immobilization, and biocatalytic utilization of proteins. The membrane shows stable performance under physiological conditions, allowing filtration of protein mixtures with a 150 kDa molecular weight cutoff (∼8 nm hydrodynamic diameter cutoff). Due to the biocompatibility of the membrane, filtered proteins stay functionally active and retained proteins can be partially recovered. Upon filtration, large enzymes become immobilized within the membrane. They exhibit stable activity when subjected to a constant flux of substrates for prolonged periods of time, which can be used to carry out heterogeneous biocatalysis. The noncovalent membrane material can be easily disassembled, purified, reassembled, and reused, showing reproducible performance after recycling. The robustness, recyclability, versatility, and biocompatibility of the supramolecular membrane may open new avenues for manipulating biological systems. PMID:23675461

  13. Co-Utilization of Glucose and Xylose for Enhanced Lignocellulosic Ethanol Production with Reverse Membrane Bioreactors

    PubMed Central

    Ishola, Mofoluwake M.; Ylitervo, Päivi; Taherzadeh, Mohammad J.

    2015-01-01

    Integrated permeate channel (IPC) flat sheet membranes were examined for use as a reverse membrane bioreactor (rMBR) for lignocellulosic ethanol production. The fermenting organism, Saccharomyces cerevisiae (T0936), a genetically-modified strain with the ability to ferment xylose, was used inside the rMBR. The rMBR was evaluated for simultaneous glucose and xylose utilization as well as in situ detoxification of furfural and hydroxylmethyl furfural (HMF). The synthetic medium was investigated, after which the pretreated wheat straw was used as a xylose-rich lignocellulosic substrate. The IPC membrane panels were successfully used as the rMBR during the batch fermentations, which lasted for up to eight days without fouling. With the rMBR, complete glucose and xylose utilization, resulting in 86% of the theoretical ethanol yield, was observed with the synthetic medium. Its application with the pretreated wheat straw resulted in complete glucose consumption and 87% xylose utilization; a final ethanol concentration of 30.3 g/L was obtained, which corresponds to 83% of the theoretical yield. Moreover, complete in situ detoxification of furfural and HMF was obtained within 36 h and 60 h, respectively, with the rMBR. The use of the rMBR is a promising technology for large-scale lignocellulosic ethanol production, since it facilitates the co-utilization of glucose and xylose; moreover, the technology would also allow the reuse of the yeast for several batches. PMID:26633530

  14. [Formylation of porphyrin platinum complexes].

    PubMed

    Rumiantseva, V D; Konovalenko, L I; Nagaeva, E A; Mironov, A F

    2005-01-01

    The formylation reaction of platinum complexes of beta-unsubstituted porphyrins was studied. The interaction of deuteroporphyrin IX derivatives with the Vilsmeyer reagent led to the selective formylation of their macrocycles in the beta position. The resulting formyl derivatives of the porphyrins are of interest for fluorescent immunoassay.

  15. Binding Specificity of the Porphyromonas gingivalis Heme and Hemoglobin Receptor HmuR, Gingipain K, and Gingipain R1 for Heme, Porphyrins, and Metalloporphyrins

    PubMed Central

    Olczak, Teresa; Dixon, Dabney White; Genco, Caroline Attardo

    2001-01-01

    Previous genetic and biochemical studies have confirmed that hemoglobin and hemin utilization in Porphyromonas gingivalis is mediated by the outer membrane hemoglobin and heme receptor HmuR, as well as gingipain K (Kgp), a lysine-specific cysteine protease, and gingipain R1 (HRgpA), one of two arginine-specific cysteine proteases. In this study we report on the binding specificity of the recombinant P. gingivalis HmuR protein and native gingipains for hemoglobin, hemin, various porphyrins, and metalloporphyrins as assessed by spectrophotometric assays, by affinity chromatography, and by enzyme-linked immunosorbent assay. Protoporphyrin, mesoporphyrin, deuteroporphyrin, hematoporphyrin, and some of their iron, copper, and zinc derivatives were examined to evaluate the role of both the central metal ion and the peripheral substituents on binding to recombinant HmuR and soluble gingipains. Scatchard analysis of hemin binding to Escherichia coli cells expressing recombinant membrane-associated six-His-tagged HmuR yielded a linear plot with a binding affinity of 2.4 × 10−5 M. Recombinant E. coli cells bound the iron, copper, and zinc derivatives of protoporphyrin IX (PPIX) with similar affinities, and approximately four times more tightly than PPIX itself, which suggests that the active site of HmuR contains a histidine that binds the metal ion in the porphyrin ring. Furthermore, we found that recombinant HmuR prefers the ethyl and vinyl side chains of the PPIX molecule to either the larger hydroxyethyl or smaller hydrogen side chains. Kgp and HRgpA were demonstrated to bind various porphyrins and metalloporphyrins with affinities similar to those for hemin, indicating that the binding of Kgp and HRgpA to these porphyrins does not require a metal within the porphyrin ring. We did not detect the binding of RgpB, the arginine-specific cysteine protease that lacks a C-terminal hemagglutinin domain, to hemoglobin, porphyrins, or metalloporphyrins. Kgp and HRgpA, but not

  16. Porphyrins in egg shells (Short Communication)

    PubMed Central

    With, Torben K.

    1974-01-01

    T.l.c. of esterified egg-shell porphyrin shows a mixture containing protoporphyrin with admixture of significant amounts of coproporphyrin, pentacarboxylic porphyrin and uroporphyrin and other, unidentified, porphyrins. This points to porphyrin biosynthesis taking place in the oviduct epithelium. ImagesPLATE 1 PMID:4420928

  17. Molecular Simulations of Porphyrins and Heme Proteins

    SciTech Connect

    SHELNUTT,JOHN A.

    2000-01-18

    An overview of the use of classical mechanical molecular simulations of porphyrins, hydroporphyrins, and heme proteins is given. The topics cover molecular mechanics calculations of structures and conformer energies of porphyrins, energies of barriers for interconversion between stable conformers, molecular dynamics of porphyrins and heme proteins, and normal-coordinate structural analysis of experimental and calculated porphyrin structures. Molecular mechanics and dynamics are currently a fertile area of research on porphyrins. In the future, other computational methods such as Monte Carlo simulations, which have yet to be applied to porphyrins, will come into use and open new avenues of research into molecular simulations of porphyrins.

  18. Damage to the microbial cell membrane during pyrolytic sugar utilization and strategies for increasing resistance.

    PubMed

    Jin, Tao; Rover, Marjorie R; Petersen, Elspeth M; Chi, Zhanyou; Smith, Ryan G; Brown, Robert C; Wen, Zhiyou; Jarboe, Laura R

    2017-05-27

    Lignocellulosic biomass is an appealing feedstock for the production of biorenewable fuels and chemicals, and thermochemical processing is a promising method for depolymerizing it into sugars. However, trace compounds in this pyrolytic sugar syrup are inhibitory to microbial biocatalysts. This study demonstrates that hydrophobic inhibitors damage the cell membrane of ethanologenic Escherichia coli KO11+lgk. Adaptive evolution was employed to identify design strategies for improving pyrolytic sugar tolerance and utilization. Characterization of the resulting evolved strain indicates that increased resistance to the membrane-damaging effects of the pyrolytic sugars can be attributed to a glutamine to leucine mutation at position 29 of carbon storage regulator CsrA. This single amino acid change is sufficient for decreasing EPS protein production and increasing membrane integrity when exposed to pyrolytic sugars.

  19. Porphyrin and heme metabolism and the porphyrias.

    PubMed

    Bonkovsky, Herbert L; Guo, Jun-Tao; Hou, Weihong; Li, Ting; Narang, Tarun; Thapar, Manish

    2013-01-01

    Porphyrins and metalloporphyrins are the key pigments of life on earth as we know it, because they include chlorophyll (a magnesium-containing metalloporphyrin) and heme (iron protoporphyrin). In eukaryotes, porphyrins and heme are synthesized by a multistep pathway that involves eight enzymes. The first and rate-controlling step is the formation of delta-aminolevulinic acid (ALA) from glycine plus succinyl CoA, catalyzed by ALA synthase. Intermediate steps occur in the cytoplasm, with formation of the monopyrrole porphobilinogen and the tetrapyrroles hydroxymethylbilane and a series of porphyrinogens, which are serially decarboxylated. Heme is utilized chiefly for the formation of hemoglobin in erythrocytes, myoglobin in muscle cells, cytochromes P-450 and mitochondrial cytochromes, and other hemoproteins in hepatocytes. The rate-controlling step of heme breakdown is catalyzed by heme oxygenase (HMOX), of which there are two isoforms, called HMOX1 and HMOX2. HMOX breaks down heme to form biliverdin, carbon monoxide, and iron. The porphyrias are a group of disorders, mainly inherited, in which there are defects in normal porphyrin and heme synthesis. The cardinal clinical features are cutaneous (due to the skin-damaging effects of excess deposited porphyrins) or neurovisceral attacks of pain, sometimes with weakness, delirium, seizures, and the like (probably due mainly to neurotoxic effects of ALA). The treatment of choice for the acute hepatic porphyrias is intravenous heme therapy, which repletes a critical regulatory heme pool in hepatocytes and leads to downregulation of hepatic ALA synthase, which is a biochemical hallmark of all forms of acute porphyria in relapse.

  20. Involvement of HxuC Outer Membrane Protein in Utilization of Hemoglobin by Haemophilus influenzae

    PubMed Central

    Cope, Leslie D.; Love, Robert P.; Guinn, Sarah E.; Gilep, Andrei; Usanov, Sergei; Estabrook, Ronald W.; Hrkal, Zbynek; Hansen, Eric J.

    2001-01-01

    Haemophilus influenzae can utilize different protein-bound forms of heme for growth in vitro. A previous study from this laboratory indicated that nontypeable Haemophilus influenzae (NTHI) strain N182 expressed three outer membrane proteins, designated HgbA, HgbB, and HgbC, that bound hemoglobin or hemoglobin-haptoglobin and were encoded by open reading frames (ORFs) that contained a CCAA nucleotide repeat. Testing of mutants expressing the HgbA, HgbB, and HgbC proteins individually revealed that expression of any one of these proteins was sufficient to allow wild-type growth with hemoglobin. In contrast, mutants that expressed only HgbA or HgbC grew significantly better with hemoglobin-haptoglobin than did a mutant expressing only HgbB. Construction of an isogenic hgbA hgbB hgbC mutant revealed that the absence of these three gene products did not affect the ability of NTHI N182 to utilize hemoglobin as a source of heme, although this mutant was severely impaired in its ability to utilize hemoglobin-haptoglobin. The introduction of a tonB mutation into this triple mutant eliminated its ability to utilize hemoglobin, indicating that the pathway for hemoglobin utilization in the absence of HgbA, HgbB, and HgbC involved a TonB-dependent process. Inactivation in this triple mutant of the hxuC gene, which encodes a predicted TonB-dependent outer membrane protein previously shown to be involved in the utilization of free heme, resulted in loss of the ability to utilize hemoglobin. The results of this study reinforce the redundant nature of the heme acquisition systems expressed by H. influenzae. PMID:11254593

  1. Affinity purification of bacterial outer membrane vesicles (OMVs) utilizing a His-tag mutant.

    PubMed

    Alves, Nathan J; Turner, Kendrick B; DiVito, Kyle A; Daniele, Michael A; Walper, Scott A

    To facilitate the rapid purification of bacterial outer membrane vesicles (OMVs), we developed two plasmid constructs that utilize a truncated, transmembrane protein to present an exterior histidine repeat sequence. We chose OmpA, a highly abundant porin protein, as the protein scaffold and utilized the lac promoter to allow for inducible control of the epitope-presenting construct. OMVs containing mutant OmpA-His6 were purified directly from Escherichia coli culture media on an immobilized metal affinity chromatography (IMAC) Ni-NTA resin. This enabling technology can be combined with other molecular tools directed at OMV packaging to facilitate the separation of modified/cargo-loaded OMV from their wt counterparts. In addition to numerous applications in the pharmaceutical and environmental remediation industries, this technology can be utilized to enhance basic research capabilities in the area of elucidating endogenous OMV function.

  2. Potentiometric detection and removal of copper using porphyrins

    PubMed Central

    2013-01-01

    Background Copper is an essential trace element with a great importance in industry, environment and biological systems. The great advantage of ion-selective sensors in comparison with other proposed techniques is that they are measuring the free metal ion activity which is responsible for their toxicity. Porphyrins are known to be among the best ionophores in formulation of ion-selective sensors. Results A symmetrically substituted meso-porphyrin, namely: 5,10,15,20-tetrakis(4-allyloxyphenyl)porphyrin (TAPP) was used in the construction of a new copper selective-sensor and was also tested for the removal of copper from waste waters. The potentiometric response characteristics (slope and selectivity) of copper-selective electrodes based on TAPP in o-nitrophenyloctylether (o-NPOE), dioctyl phtalate (DOP) and dioctyl sebacate (DOS) plasticized with poly(vinyl chloride) membranes are compared. Conclusions The best results were obtained for the membrane plasticized with DOP. The sensor has linear response in the range 1x10-7 – 1x10-1 M with 28.4 ± 0.4 mV/decade near-Nernstian slope towards copper ions and presents good selectivity. Due to its chelating nature, the same porphyrin was also tested for the retention of copper from synthetic copper samples, showing a maximum adsorption capacity of 280 mg/g. PMID:23829792

  3. Fabrication of Polymer Electrolyte Membrane Fuel Cell MEAs Utilizing Inkjet Print Technology

    SciTech Connect

    Towne, Silas A.; Viswanathan, Vish V.; Holbery, Jim; Rieke, Peter C.

    2007-09-27

    Utilizing drop-on-demand technology, we have successfully developed hydrogen-air polymer electrolyte membrane fuel cells (PEMFC) and have demonstrated their performance to be similar to conventionally fabricated systems. Prototype membrane electrode assemblies (MEAs) were fabricated utilizing commercial desktop inkjet printers by depositing the active catalyst electrode layer directly from print cartridges onto a Nafion® polymer membrane. Preliminary results indicate open circuit voltages up to 0.84 V and power densities of 31 mW/cm2 as compared to 0.9 V and 42 mW/cm2 for commercial MEAs tested on our experimental test apparatus. The objective of this work is to demonstrate that drop-on-demand technology can be used to produce MEAs comparable in structure and performance to commercially available MEAs and to demonstrate that this approach provides highly controlled and repeatable automated processing that can result in improved precious metal catalyst efficiency, improved structural integrity and ultimately reduced PEMFC MEA materials and fabrication costs.

  4. Fabrication of a nanosize-Pt-embedded membrane electrode assembly to enhance the utilization of Pt in proton exchange membrane fuel cells.

    PubMed

    Choe, Junseok; Kim, Doyoung; Shim, Jinyong; Lee, Inhae; Tak, Yongsug

    2011-08-01

    A procedure to locate the Pt nanostructure inside the hydrophilic channel of a Nafion membrane was developed in order to enhance Pt utilization in PEMFCs. Nanosize Pt-embedded MEA was constructed by Cu electroless plating and subsequent Pt electrodeposition inside the hydrophilic channels of the Nafion membrane. The metallic Pt nanostructure fabricated inside the membrane was employed as an oxygen reduction catalyst for a PEMFC and facilitated effective use of the hydrophilic channels inside the membrane. Compared to the conventional MEA, a Pt-embedded MEA with only 68% Pt loading showed better PEMFC performance.

  5. Porphyrin binding with blood cells

    NASA Astrophysics Data System (ADS)

    Zorin, Vladimir P.; Khludeyev, Ivan I.; Savitsky, Valery P.; Mel'nov, Sergey B.; Kochubeyeva, Nina D.

    1997-12-01

    Using fluorescence activated cell sorting we have compared the binding of a number of porphyrins with different polarity by blood cells. According to pigment level blood cells may be arranged in order granulocytes greater than or equal to monocytes greater than lymphocytes greater than erythrocytes. Cellular accumulation of selected porphyrins in blood cells was remarkably different. The equilibrium level of chlorin e6 dimethylester in blood cells was about 15 times higher compared with chlorin e6. As a result, the percentage of pigment binding by blood cells varied from 0% (of total amount) in the case of polar pigments to about 50% for moderately apolar porphyrins. The results obtained show that pigment binding to blood cells may be of certain value when the pharmacokinetic behavior of porphyrin sensitizer is analyzed.

  6. Photochemical solar energy conversion utilizing semiconductors localized in membrane-mimetic systems. Performance report, April 1, 1989--August 31, 1991

    SciTech Connect

    Fendler, J.H.

    1991-08-31

    Extending the frontiers of colloidal photochemistry and colloidal electrochemistry to solar photochemistry research had been the main objective of this research. More specific objectives of this proposal include the examination of semiconductor-particle-mediated photoelectron transfer and photoelectric effects in different membrane mimetic systems. Emphasis had been placed on developing bilayer lipid membranes and Langmuir-Blodgett films as new membrane-mimetic systems, as well as on the characterization and utilization of these systems.

  7. Heteroatom-Containing Porphyrin Analogues.

    PubMed

    Chatterjee, Tamal; Shetti, Vijayendra S; Sharma, Ritambhara; Ravikanth, Mangalampalli

    2017-02-22

    The heteroatom-containing porphyrin analogues or core-modified porphyrins that resulted from the replacement of one or two pyrrole rings with other five-membered heterocycles such as furan, thiophene, selenophene, tellurophene, indene, phosphole, and silole are highly promising macrocycles and exhibit quite different physicochemical properties compared to regular azaporphyrins. The properties of heteroporphyrins depend on the nature and number of different heterocycle(s) present in place of pyrrole ring(s). The heteroporphyrins provide unique and unprecedented coordination environments for metals. Unlike regular porphyrins, the monoheteroporphyrins are known to stabilize metals in unusual oxidation states such as Cu and Ni in +1 oxidation states. The diheteroporphyrins, which are neutral macrocycles without ionizable protons, also showed interesting coordination chemistry. Thus, significant progress has been made in last few decades on core-modified porphyrins in terms of their synthesis, their use in building multiporphyrin arrays for light-harvesting applications, their use as ligands to form interesting metal complexes, and also their use for several other studies. The synthetic methods available in the literature allow one to prepare mono- and diheteroporphyrins and their functionalized derivatives, which were used extensively to prepare several covalent and noncovalent heteroporphyrin-based multiporphyrin arrays. The methods are also developed to synthesize different hetero analogues of porphyrin derivatives such as heterocorroles, heterochlorins, heterocarbaporphyrinoids, heteroatom-substituted confused porphyrins, and so on. This Review summarizes the key developments that have occurred in heteroporphyrin chemistry over the last four decades.

  8. Porphyrins at interfaces

    NASA Astrophysics Data System (ADS)

    Auwärter, Willi; Écija, David; Klappenberger, Florian; Barth, Johannes V.

    2015-02-01

    Porphyrins and other tetrapyrrole macrocycles possess an impressive variety of functional properties that have been exploited in natural and artificial systems. Different metal centres incorporated within the tetradentate ligand are key for achieving and regulating vital processes, including reversible axial ligation of adducts, electron transfer, light-harvesting and catalytic transformations. Tailored substituents optimize their performance, dictating their arrangement in specific environments and mediating the assembly of molecular nanoarchitectures. Here we review the current understanding of these species at well-defined interfaces, disclosing exquisite insights into their structural and chemical properties, and also discussing methods by which to manipulate their intramolecular and organizational features. The distinct characteristics arising from the interfacial confinement offer intriguing prospects for molecular science and advanced materials. We assess the role of surface interactions with respect to electronic and physicochemical characteristics, and describe in situ metallation pathways, molecular magnetism, rotation and switching. The engineering of nanostructures, organized layers, interfacial hybrid and bio-inspired systems is also addressed.

  9. The effect on photohaemolysis of variation in the structure of the porphyrin photosensitizer.

    PubMed Central

    de Paolis, A; Chandra, S; Charalambides, A A; Bonnett, R; Magnus, I A

    1985-01-01

    A comparison of the photosensitizing ability of a variety of porphyrins for photohaemolysis gives the following order of activity: protoporphyrin greater than deuteroporphyrin, mesoporphyrin, haematoporphyrin dimethyl ester much greater than haematoporphyrin diacetate, haematoporphyrin greater than haematoporphyrin monoacetate, coproporphyrin III, haematoporphyrin derivative, coproporphyrin III tetramethyl ester greater than uroporphyrin I, meso-tetra-(N-methyl-4-pyridinium)porphyrin tetratoluene-p-sulphonate, meso-tetra-(p-carboxyphenyl)porphyrin, protoporphyrin dimethyl ester, meso-tetra-(p-hydroxy-sulphonylphenyl)porphyrin tetrasodium salt, uroporphyrin III, deuteroporphyrin-3,8-disulphonic acid and protohaemin. The results for the metal-free porphyrins are rationalized in terms of solubility and partition properties, and a model is proposed for the incorporation of amphipathic porphyrins into the membrane lipid bilayer. Experiments with erythrocytes from patients with erythropoeitic protoporphyria and with normal erythrocytes to which porphyrin was added in a deuterium oxide medium do not lead to an increase in the rate of photohaemolysis. A possible explanation for this somewhat surprising observation is outlined. PMID:2985045

  10. Palladium-catalyzed amination of meso-(bromophenyl)porphyrins with diamines and azamacrocycles.

    PubMed

    Mikhalitsyna, E A; Tyurin, V S; Khrustalev, V N; Lonin, I S; Beletskaya, I P

    2014-03-07

    Novel diamino and azamacrocycle functionalized porphyrins were efficiently synthesized by palladium-catalyzed amination of mono- and bis(meso-(bromophenyl))porphyrins. The optimization of reaction conditions allowed us to achieve high yields of products with substrates of different types. Supramolecular utility of the thus obtained aminoporphyrins was shown by investigations of processes of coordination self-assembly in solution by NMR and UV-Vis spectroscopy. The crystalline 1D-coordination polymer formed via self-assembly of N,N-dimethylethylenediamine substituted zinc porphyrin was characterized by X-ray diffraction.

  11. Preparation and biodistribution of copper-67-labeled porphyrins and porphyrin-A6H immunoconjugates.

    PubMed

    Bhalgat, M K; Roberts, J C; Mercer-Smith, J A; Knotts, B D; Vessella, R L; Lavallee, D K

    1997-02-01

    The synthetic porphyrins, N-benzyl-5,10,15,20-tetrakis (4-carboxyphenyl) porphine (N-bzHTCPP) and N-4-nitrobenzyl-5-(4-carboxyphenyl)-10,15,20-tris(4-sulfophenyl) porphine (N-bzHCS3P), represent excellent radiocopper chelating agents that may find utility in antibody-mediated diagnosis and/or therapy. N-bzHCS3P was conjugated to an anti-renal cell carcinoma (RCC) antibody, A6H, and labeled with copper-67. 67CuCS3P-A6H was studied for its biodistribution in human RCC xenograft-bearing nude mice, along with the radiolabeled free porphyrins. The porphyrins resulted in tumor:blood ratios in the range of 3 to 4 after 48 h. The radiolabeled antibody achieved a tumor:blood ratio of over 16 after 45 h, indicating accumulation at the desired site. However, unwanted localization also occurred in the liver and spleen, which will have to be rectified before realizing the full potential of this approach.

  12. Utilizing collagen membranes for guided tissue regeneration-based root coverage.

    PubMed

    Wang, Hom-Lay; Modarressi, Marmar; Fu, Jia-Hui

    2012-06-01

    Gingival recession is a common clinical problem that can result in hypersensitivity, pain, root caries and esthetic concerns. Conventional soft tissue procedures for root coverage require an additional surgical site, thereby causing additional trauma and donor site morbidity. In addition, the grafted tissues heal by repair, with formation of long junctional epithelium with some connective tissue attachment. Guided tissue regeneration-based root coverage was thus developed in an attempt to overcome these limitations while providing comparable clinical results. This paper addresses the biologic foundation of guided tissue regeneration-based root coverage, and describes the indications and contraindications for this technique, as well as the factors that influence outcomes. The step-by-step clinical techniques utilizing collagen membranes are also described. In comparison with conventional soft tissue procedures, the benefits of guided tissue regeneration-based root coverage procedures include new attachment formation, elimination of donor site morbidity, less chair-time, and unlimited availability and uniform thickness of the product. Collagen membranes, in particular, benefit from product biocompatibility with the host, while promoting chemotaxis, hemostasis, and exchange of gas and nutrients. Such characteristics lead to better wound healing by promoting primary wound coverage, angiogenesis, space creation and maintenance, and clot stability. In conclusion, collagen membranes are a reliable alternative for use in root coverage procedures.

  13. Kinetic characteristics of porphyrin distribution in the blood

    NASA Astrophysics Data System (ADS)

    Zorin, Vladimir P.; Khludeyev, Ivan I.; Mikhalovsky, Iosif S.; Zorina, Tatyana E.; Savitsky, Valery P.; Mel'nov, Sergey B.; Kochubeyeva, Nina D.; Kravchenko, Irina E.

    1999-12-01

    The objectives of the present work were to compare the kinetics of porphyrin exchange between different plasma lipoproteins and biological membranes. Isolated proteins were loaded by porphyrins (chlorin e6 derivatives and Zn- phthalocyanine) and the kinetics of pigment transfer from protein carrier to pigment-free proteins or biological membranes were analyzed by spectroscopic techniques. It was obtained that the rate of exchange depended strongly on the pigment polarity. A main trend was that the time required for equilibrium redistribution increased with decreasing dyes polarity. Its values changed from seconds for polar sensitizers to tens of minutes in the case of apolar dyes. Extremely slow redistribution (several hours) was observed when the recovery of apolar pigments (chlorin e6 trimethylester and Zn-phthalocyanine) from LDL was studied. The results clear indicate that the rate of pigment exchange between proteins and cells may contribute to the control of sensitizer distribution in blood and solid tissues.

  14. Novel porphyrin-preparation, characterization, and applications in solar energy conversion.

    PubMed

    Lu, Jianfeng; Li, Hao; Liu, Shuangshuang; Chang, Yu-Cheng; Wu, Hui-Ping; Cheng, Yibing; Wei-Guang Diau, Eric; Wang, Mingkui

    2016-03-07

    Porphyrins have been demonstrated as one of the most efficient sensitizers in dye-sensitized solar cells (DSSC). Herein, we investigated a series of porphyrin sensitizers functionalized with various π-spacers, such as phenyl for LD14, thiophene for LW4, thiophene-phenyl for LW5, and 2,1,3-benzothiadiazole (BTD)-phenyl for LW24. Photo-physical investigation by means of time-resolved fluorescence and nanosecond transient absorption spectroscopy revealed an accelerated inner charge transfer in porphyrins containing the BTD-phenyl π-spacer. Implementation of an auxiliary electron-deficient BTD unit to the porphyrin spacer also results in a broad light-harvesting ability extending up to 840 nm, contributing to an enhanced charge transfer character from the porphyrin ring to the anchoring group. When utilized as a sensitizer in DSSCs, the LW24 device achieved a power conversion efficiency of 9.2%, higher than those based on LD14 or LW5 porphyrins (PCE 9.0% or 8.2%, respectively) but lower than that of the LW4 device (PCE 9.5%). Measurements of transient photovoltage decays demonstrate that the LW24 device features the up-shifted potential band edge of the conduction band of TiO2, but involves serious charge recombination in the dye/TiO2 interface. The findings provide insights into the molecular structure and the charge-transfer characteristics for designing efficient porphyrin sensitizers for DSSC applications.

  15. Antimicrobial and antiviral activity of porphyrin photosensitization

    NASA Astrophysics Data System (ADS)

    Malik, Zvi; Ladan, Hava; Nitzan, Yeshayahu; Smetana, Zehava

    1994-03-01

    In order to photosensitize Gram (-) bacteria such as Pseudomonas aeuruginosa and Escherichia coli, we introduced the small peptide polymyxin-B nona-peptide (PBNP) which stimulated the translocation of porphyrin through the outer membrane of these bacteria and makes PDT possible. Gram negative cell killing by the use of PBNP and DP broadens the antibacterial spectrum of photodynamic inactivation and opens new horizons for this modality as a wide spectrum drug when antibiotic resistance is the main concern. Plasmidial and chromosomal DNA damage in S. aureus and E. coli cells was mediated by DP photosensitization. The major observation was the disappearance of the plasmid supercoiled fraction. The chromosomal DNA was also affected and its degradation products were detected after treatment.

  16. A Novel System for Carbon Dioxide Capture Utilizing Electrochemical Membrane Technology

    SciTech Connect

    Ghezel-Ayagh, Hossein; Jolly, Stephen; Patel, Dilip; Hunt, Jennifer; Steen, William A.; Richardson, Carl F.; Marina, Olga A.

    2013-06-03

    FuelCell Energy, Inc. (FCE), in collaboration with Pacific Northwest National Laboratory (PNNL) and URS Corporation, is developing a novel Combined Electric Power and Carbon-Dioxide Separation (CEPACS) system, under a contract from the U.S. Department of Energy (DE-FE0007634), to efficiently and cost effectively separate carbon dioxide from the emissions of existing coal fired power plants. The CEPACS system is based on FCE’s electrochemical membrane (ECM) technology utilizing the Company’s internal reforming carbonate fuel cell products carrying the trade name of Direct FuelCell® (DFC®). The unique chemistry of carbonate fuel cells offers an innovative approach for separation of CO2 from existing fossil-fuel power plant exhaust streams (flue gases). The ECM-based CEPACS system has the potential to become a transformational CO2-separation technology by working as two devices in one: it separates the CO2 from the exhaust of other plants such as an existing coal-fired plant and simultaneously produces clean and environmentally benign (green) electric power at high efficiency using a supplementary fuel. The overall objective of this project is to successfully demonstrate the ability of FCE’s electrochemical membrane-based CEPACS system technology to separate ≥ 90% of the CO2 from a simulated Pulverized Coal (PC) power plant flue-gas stream and to compress the captured CO2 to a state that can be easily transported for sequestration or beneficial use. Also, a key project objective is to show, through a Technical and Economic Feasibility Study and bench scale testing (11.7 m2 area ECM), that the electrochemical membrane-based CEPACS system is an economical alternative for CO2 capture in PC power plants, and that it meets DOE objectives for the incremental cost of electricity (COE) for post-combustion CO2 capture.

  17. Intracellular transport of viruses and their components: utilizing the cytoskeleton and membrane highways.

    PubMed

    Harries, Phillip A; Schoelz, James E; Nelson, Richard S

    2010-11-01

    Plant viruses are obligate organisms that require host components for movement within and between cells. A mechanistic understanding of virus movement will allow the identification of new methods to control virus systemic spread and serve as a model system for understanding host macromolecule intra- and intercellular transport. Recent studies have moved beyond the identification of virus proteins involved in virus movement and their effect on plasmodesmal size exclusion limits to the analysis of their interactions with host components to allow movement within and between cells. It is clear that individual virus proteins and replication complexes associate with and, in some cases, traffic along the host cytoskeleton and membranes. Here, we review these recent findings, highlighting the diverse associations observed between these components and their trafficking capacity. Plant viruses operate individually, sometimes within virus species, to utilize unique interactions between their proteins or complexes and individual host cytoskeletal or membrane elements over time or space for their movement. However, there is not sufficient information for any plant virus to create a complete model of its intracellular movement; thus, more research is needed to achieve that goal.

  18. Self-assembly of DNA-porphyrin hybrid molecules for the creation of antimicrobial nanonetwork.

    PubMed

    Kumari, Rina; Khan, Mohd Imran; Bhowmick, Sourav; Sinha, Kislay K; Das, Neeladri; Das, Prolay

    2017-07-01

    DNA derived well-controlled arrangement of porphyrins has emerged as promising hybrid nanostructures. Exceptional biocompatibility and DNA-directed surface addressability coupled with rich symmetry features of the porphyrin have made these hybrid nanostructures attractive candidates for potential biomedical and biotechnological applications. However, the noteworthy photophysical properties of porphyrin and related molecules when present in DNA based nanostructures are yet to be explored fully and should be a matter of intense research that may unearth a plethora of interesting applications of these nanostructures. Herein, we demonstrate the construction of novel self-assembled DNA-porphyrin hybrid nanonetworks that utilize the porphyrin core for antibacterial applications. Porphyrin derivative with four pendant NH2 groups was synthesized and conjugated with the 5'-PO4 of ss-DNA by solution phase phosphoramidation coupling reaction. The conjugation was followed by DNA hybridization mediated self-assembly to form DNA-porphyrin hybrid nanonetwork. The enhanced antimicrobial property of the nanonetwork was envisioned following light irradiation at relevant wavelength. In line with this, comparative antimicrobial activities against gram-negative (Escherichia coli BL-21) and gram-positive bacteria (Staphylococcus aureus) have been studied. Interestingly, DNA-porphyrin nanonetwork afforded highly efficient and coherent photoinduced reactive oxygen species (ROS) generation to display antimicrobial activity against Staphylococcus aureus. The escalated and coherent ROS generation from the nanonetworks was attributed to the ordered placement of the porphyrins that inhibits self-quenching. Our work points out to a good alternative for antibiotic free strategies for preservation of biological materials and other applications. Copyright © 2017. Published by Elsevier B.V.

  19. Iron Nitrosyl “Natural” Porphyrinates: Does the Porphyrin Matter?

    PubMed Central

    2015-01-01

    The synthesis and spectroscopic characterization of three five-coordinate nitrosyliron(II) complexes, [Fe(Porph)(NO)], are reported. These three nitrosyl derivatives, where Porph represents protoporphyrin IX dimethyl ester, mesoporphyrin IX dimethyl ester, or deuteroporphyrin IX dimethyl ester, display notable differences in their properties relative to the symmetrical synthetic porphyrins such as OEP and TPP. The N–O stretching frequencies are in the range of 1651–1660 cm–1, frequencies that are lower than those of synthetic porphyrin derivatives. Mössbauer spectra obtained in both zero and applied magnetic field show that the quadrupole splitting values are slightly larger than those of known synthetic porphyrins. The electronic structures of these naturally occurring porphyrin derivatives are thus seen to be consistently different from those of the synthetic derivatives, the presumed consequence of the asymmetric peripheral substituent pattern. The molecular structure of [Fe(PPIX-DME)(NO)] has been determined by X-ray crystallography. Although disorder of the axial nitrosyl ligand limits the structural quality, this derivative appears to show the same subtle structural features as previously characterized five-coordinate nitrosyls. PMID:24620710

  20. Fusing Porphyrins and Phospholes: Synthesis and Analysis of a Phosphorus-Containing Porphyrin.

    PubMed

    Higashino, Tomohiro; Yamada, Tomoki; Sakurai, Tsuneaki; Seki, Shu; Imahori, Hiroshi

    2016-09-26

    A phosphole-fused porphyrin dimer, as a representative of a new class of porphyrins with a phosphorus atom, was synthesized for the first time. The porphyrin dimer exhibits remarkably broadened absorption, indicating effective π-conjugation over the two porphyrins through the phosphole moiety. The porphyrin dimer possesses excellent electron-accepting character, which is comparable to that of a representative electron-accepting material, [60]PCBM. These results provide access to a new class of phosphorus-containing porphyrins with unique optoelectronic properties.

  1. TonB-dependent outer-membrane proteins and siderophore utilization in Pseudomonas fluorescens Pf-5.

    PubMed

    Hartney, Sierra L; Mazurier, Sylvie; Kidarsa, Teresa A; Quecine, Maria Carolina; Lemanceau, Philippe; Loper, Joyce E

    2011-04-01

    The soil bacterium Pseudomonas fluorescens Pf-5 produces two siderophores, a pyoverdine and enantio-pyochelin, and its proteome includes 45 TonB-dependent outer-membrane proteins, which commonly function in uptake of siderophores and other substrates from the environment. The 45 proteins share the conserved β-barrel and plug domains of TonB-dependent proteins but only 18 of them have an N-terminal signaling domain characteristic of TonB-dependent transducers (TBDTs), which participate in cell-surface signaling systems. Phylogenetic analyses of the 18 TBDTs and 27 TonB-dependent receptors (TBDRs), which lack the N-terminal signaling domain, suggest a complex evolutionary history including horizontal transfer among different microbial lineages. Putative functions were assigned to certain TBDRs and TBDTs in clades including well-characterized orthologs from other Pseudomonas spp. A mutant of Pf-5 with deletions in pyoverdine and enantio-pyochelin biosynthesis genes was constructed and characterized for iron-limited growth and utilization of a spectrum of siderophores. The mutant could utilize as iron sources a large number of pyoverdines with diverse structures as well as ferric citrate, heme, and the siderophores ferrichrome, ferrioxamine B, enterobactin, and aerobactin. The diversity and complexity of the TBDTs and TBDRs with roles in iron uptake clearly indicate the importance of iron in the fitness and survival of Pf-5 in the environment.

  2. Micelle-Encapsulated Quantum Dot-Porphyrin Assemblies as in Vivo Two-Photon Oxygen Sensors.

    PubMed

    Lemon, Christopher M; Karnas, Elizabeth; Han, Xiaoxing; Bruns, Oliver T; Kempa, Thomas J; Fukumura, Dai; Bawendi, Moungi G; Jain, Rakesh K; Duda, Dan G; Nocera, Daniel G

    2015-08-12

    Micelles have been employed to encapsulate the supramolecular assembly of quantum dots with palladium(II) porphyrins for the quantification of O2 levels in aqueous media and in vivo. Förster resonance energy transfer from the quantum dot (QD) to the palladium porphyrin provides a means for signal transduction under both one- and two-photon excitation. The palladium porphyrins are sensitive to O2 concentrations in the range of 0-160 Torr. The micelle-encapsulated QD-porphyrin assemblies have been employed for in vivo multiphoton imaging and lifetime-based oxygen measurements in mice with chronic dorsal skinfold chambers or cranial windows. Our results establish the utility of the QD-micelle approach for in vivo biological sensing applications.

  3. Energy transfer on demand: photoswitch-directed behavior of metal-porphyrin frameworks.

    PubMed

    Williams, Derek E; Rietman, Joseph A; Maier, Josef M; Tan, Rui; Greytak, Andrew B; Smith, Mark D; Krause, Jeanette A; Shustova, Natalia B

    2014-08-27

    In this paper, a photochromic diarylethene-based derivative that is coordinatively immobilized within an extended porphyrin framework is shown to maintain its photoswitchable behavior and to direct the photophysical properties of the host. In particular, emission of a framework composed of bis(5-pyridyl-2-methyl-3-thienyl)cyclopentene (BPMTC) and tetrakis(4-carboxyphenyl)porphyrin (H4TCPP) ligands anchored by Zn(2+) ions can be altered as a function of incident light. We attribute the observed cyclic fluorescence behavior of the synthesized porphyrin-BPMTC array to activation of energy transfer (ET) pathways through BPMTC photoisomerization. Time-resolved photoluminescence measurements show a decrease in average porphyrin emission lifetime upon BPMTC insertion, consistent with an ET-based mechanism. These studies portend the possible utilization of photochromic ligands to direct chromophore behavior in large light-harvesting ensembles.

  4. Bis(cyano)iron(III) Porphyrinates: What is the Ground State?

    PubMed Central

    Li, Jianfeng; Noll, Bruce C.; Schulz, Charles E.; Scheidt, W. Robert

    2015-01-01

    The synthesis of six new bis(cyano) iron(III) porphyrinate derivatives is reported. The anionic porphyrin complexes utilized tetraphenylporphyrin, tetramesitylporphyrin, and tetratolylporphyrin as the porphyrin ligand. The potassium salts of Kryptofix-222 and 18-C-6 were used as the cations. These complexes have been characterized by X-ray structure analysis, solid-state Mössbauer spectroscopy, and EPR spectroscopy, both in frozen CH2Cl2 solution and the microcrystalline state. These data show that these anionic complexes can exist in either the (dxz,dyz)4(dxy)1 or (dxy)2(dxz,dyz)3 electronic configuration and some can clearly readily interconvert. This is a reflection that these two states can be very close in energy. In addition to the effects of varying the porphyrin ligand, subtle effects of the cyanide ligand environment in the solid-state and in solution are sufficient to shift the balance between the two electronic states. PMID:26098173

  5. Micelle-Encapsulated Quantum Dot-Porphyrin Assemblies as in Vivo Two-Photon Oxygen Sensors

    PubMed Central

    Lemon, Christopher M.; Karnas, Elizabeth; Han, Xiaoxing; Bruns, Oliver T.; Kempa, Thomas J.; Fukumura, Dai; Bawendi, Moungi G.; Jain, Rakesh K.; Duda, Dan G.; Nocera, Daniel G.

    2016-01-01

    Micelles have been employed to encapsulate the supramolecular assembly of quantum dots with palladium(II) porphyrins for the quantification of O2 levels in aqueous media and in vivo. Förster resonance energy transfer from the quantum dot (QD) to the palladium porphyrin provides a means for signal transduction under both one- and two-photon excitation. The palladium porphyrins are sensitive to O2 concentrations in the range of 0–160 Torr. The micelle-encapsulated QD-porphyrin assemblies have been employed for in vivo multiphoton imaging and lifetime-based oxygen measurements in mice with chronic dorsal skinfold chambers or cranial windows. Our results establish the utility of the QD-micelle approach for in vivo biological sensing applications. PMID:26149349

  6. Bis(cyano) Iron(III) Porphyrinates: What Is the Ground State?

    PubMed

    Li, Jianfeng; Noll, Bruce C; Schulz, Charles E; Scheidt, W Robert

    2015-07-06

    The synthesis of six new bis(cyano) iron(III) porphyrinate derivatives is reported. The anionic porphyrin complexes utilized tetraphenylporphyrin, tetramesitylporphyrin, and tetratolylporphyrin as the porphyrin ligand. The potassium salts of Kryptofix-222 and 18-C-6 were used as the cations. These complexes have been characterized by X-ray structure analysis, solid-state Mössbauer spectroscopy, and EPR spectroscopy, both in frozen CH2Cl2 solution and in the microcrystalline state. These data show that these anionic complexes can exist in either the (dxz,dyz)(4)(dxy)(1) or the (dxy)(2)(dxz,dyz)(3) electronic configuration and some can clearly readily interconvert. This is a reflection that these two states can be very close in energy. In addition to the effects of varying the porphyrin ligand, subtle effects of the cyanide ligand environment in the solid state and in solution are sufficient to shift the balance between the two electronic states.

  7. Self-Organized Porphyrinic Materials

    PubMed Central

    Drain, Charles Michael; Varotto, Alessandro; Radivojevic, Ivana

    2009-01-01

    The self-assembly and self-organization of porphyrins and related macrocycles enables the bottom-up fabrication of photonic materials for fundamental studies of the photophysics of these materials and for diverse applications. This rapidly developing field encompasses a broad range of disciplines including molecular design and synthesis, materials formation and characterization, and the design and evaluation of devices. Since the self-assembly of porphyrins by electrostatic interactions in the late 1980s to the present, there has been an ever increasing degree of sophistication in the design of porphyrins that self-assemble into discrete arrays or self-organize into polymeric systems. These strategies exploit ionic interactions, hydrogen bonding, coordination chemistry, and dispersion forces to form supramolecular systems with varying degrees of hierarchical order. This review concentrates on the methods to form supramolecular porphyrinic systems by intermolecular interactions other than coordination chemistry, the characterization and properties of these photonic materials, and the prospects for using these in devices. The review is heuristically organized by the predominant intermolecular interactions used and emphasizes how the organization affects properties and potential performance in devices. PMID:19253946

  8. Tailoring porphyrin-based electron accepting materials for organic photovoltaics.

    PubMed

    Rawson, Jeff; Stuart, Andrew C; You, Wei; Therien, Michael J

    2014-12-17

    The syntheses, potentiometric responses, optical spectra, electronic structural properties, and integration into photovoltaic devices are described for ethyne-bridged isoindigo-(porphinato)zinc(II)-isoindigo chromophores built upon either electron-rich 10,20-diaryl porphyrin (Ar-Iso) or electron-deficient 10,20-bis(perfluoroalkyl)porphyrin (Rf-Iso) frameworks. These supermolecules evince electrochemical responses that trace their geneses to their respective porphyrinic and isoindigoid subunits. The ethyne linkage motif effectively mixes the comparatively weak isoindigo-derived visible excitations with porphyrinic π-π* states, endowing Ar-Iso and Rf-Iso with high extinction coefficient (ε ∼ 10(5) M(-1)·cm(-1)) long-axis polarized absorptions. Ar-Iso and Rf-Iso exhibit total absorptivities per unit mass that greatly exceed that for poly(3-hexyl)thiophene (P3HT) over the 375-900 nm wavelength range where solar flux is maximal. Time-dependent density functional theory calculations highlight the delocalized nature of the low energy singlet excited states of these chromophores, demonstrating how coupled oscillator photophysics can yield organic photovoltaic device (OPV) materials having absorptive properties that supersede those of conventional semiconducting polymers. Prototype OPVs crafted from the poly(3-hexyl)thiophene (P3HT) donor polymer and these new materials (i) confirm that solar power conversion depends critically upon the driving force for photoinduced hole transfer (HT) from these low-band-gap acceptors, and (ii) underscore the importance of the excited-state reduction potential (E(-/*)) parameter as a general design criterion for low-band-gap OPV acceptors. OPVs constructed from Rf-Iso and P3HT define rare examples whereby the acceptor material extends the device operating spectral range into the NIR, and demonstrate for the first time that high oscillator strength porphyrinic chromophores, conventionally utilized as electron donors in OPVs, can also

  9. Supramolecular Allosteric Cofacial Porphyrin Complexes

    SciTech Connect

    Oliveri, Christopher G.; Gianneschi, Nathan C.; Nguyen, Son Binh T.; Mirkin, Chad A.; Stern, Charlotte L.; Wawrzak, Zdzislaw; Pink, Maren

    2008-04-12

    Nature routinely uses cooperative interactions to regulate cellular activity. For years, chemists have designed synthetic systems that aim toward harnessing the reactivity common to natural biological systems. By learning how to control these interactions in situ, one begins to allow for the preparation of man-made biomimetic systems that can efficiently mimic the interactions found in Nature. To this end, we have designed a synthetic protocol for the preparation of flexible metal-directed supramolecular cofacial porphyrin complexes which are readily obtained in greater than 90% yield through the use of new hemilabile porphyrin ligands with bifunctional ether-phosphine or thioether-phosphine substituents at the 5 and 15 positions on the porphyrin ring. The resulting architectures contain two hemilabile ligand-metal domains (Rh{sup I} or Cu{sup I} sites) and two cofacially aligned porphyrins (Zn{sup II} sites), offering orthogonal functionalities and allowing these multimetallic complexes to exist in two states, 'condensed' or 'open'. Combining the ether-phosphine ligand with the appropriate Rh{sup I} or Cu{sup I} transition-metal precursors results in 'open' macrocyclic products. In contrast, reacting the thioether-phosphine ligand with RhI or CuI precursors yields condensed structures that can be converted into their 'open' macrocyclic forms via introduction of additional ancillary ligands. The change in cavity size that occurs allows these structures to function as allosteric catalysts for the acyl transfer reaction between X-pyridylcarbinol (where X = 2, 3, or 4) and 1-acetylimidazole. For 3- and 4-pyridylcarbinol, the 'open' macrocycle accelerates the acyl transfer reaction more than the condensed analogue and significantly more than the porphyrin monomer. In contrast, an allosteric effect was not observed for 2-pyridylcarbinol, which is expected to be a weaker binder and is unfavorably constrained inside the macrocyclic cavity.

  10. Supramolecular Allosteric Cofacial Porphyrin Complexes

    PubMed Central

    Oliveri, Christopher G.; Gianneschi, Nathan C.; Nguyen, SonBinh T.; Mirkin, Chad A.; Stern, Charlotte L.; Wawrzak, Zdzislaw; Pink, Maren

    2008-01-01

    Nature routinely uses cooperative interactions to regulate cellular activity. For years, chemists have designed synthetic systems that aim toward harnessing the reactivity common to natural biological systems. By learning how to control these interactions in situ, one begins to allow for the preparation of man-made biomimetic systems that can efficiently mimic the interactions found in Nature. To this end, we have designed a synthetic protocol for the preparation of flexible metal-directed supramolecular cofacial porphyrin complexes which are readily obtained in greater than 90% yield through the use of new hemilabile porphyrin ligands with bifunctional ether–phosphine or thioether–phosphine substituents at the 5 and 15 positions on the porphyrin ring. The resulting architectures contain two hemilabile ligand–metal domains (RhI or CuI sites) and two cofacially aligned porphyrins (ZnII sites), offering orthogonal functionalities and allowing these multimetallic complexes to exist in two states, “condensed” or “open”. Combining the ether–phosphine ligand with the appropriate RhI or CuI transition-metal precursors results in “open” macrocyclic products. In contrast, reacting the thioether–phosphine ligand with RhI or CuI precursors yields condensed structures that can be converted into their “open” macrocyclic forms via introduction of additional ancillary ligands. The change in cavity size that occurs allows these structures to function as allosteric catalysts for the acyl transfer reaction between X-pyridylcarbinol (where X = 2, 3, or 4) and 1-acetylimidazole. For 3-and 4-pyridylcarbinol, the “open” macrocycle accelerates the acyl transfer reaction more than the condensed analogue and significantly more than the porphyrin monomer. In contrast, an allosteric effect was not observed for 2-pyridylcarbinol, which is expected to be a weaker binder and is unfavorably constrained inside the macrocyclic cavity. PMID:17165783

  11. The Antimicrobial Activity of Porphyrin Attached Polymers

    NASA Astrophysics Data System (ADS)

    Thompson, Lesley

    2008-03-01

    We are interested in testing the antimicrobial activity of a porphyrin that is attached to a polymer. The porphyrin (5-(4-carboxyphenyl)-10,15,20-tris-(4-pryridyl)) was synthesized from methyl 4-formyl benzoate, 4-pyridinecarboxaldehyde, and pyrrole and attached to a copolymer of polystyrene/poly(vinyl benzyl chloride), which was synthesized by free radical polymerization. The antimicrobial activity of the polymer-attached porphyrin was then determined for gram-negative E. Coli grown to 0.80 OD. In this procedure, glass slides were coated with polymer-attached porphyrin via dip-coating, and the E. Coli bacteria were plated in Luria Broth media. The plates were subsequently exposed to light overnight before they were incubated as porphyrins act as photo-sensitizers when irradiated with light. The polymer-attached porphyrin did exhibit antimicrobial activity and parameters that affect its efficiency will be discussed.

  12. Ion-conduction mechanisms in NaSICON-type membranes for energy storage and utilization

    SciTech Connect

    McDaniel, Anthony H.; Ihlefeld, Jon F.; Bartelt, Norman Charles

    2015-10-01

    Next generation metal-ion conducting membranes are key to developing energy storage and utilization technologies like batteries and fuel ce lls. Sodium super-ionic conductors (aka NaSICON) are a class of compounds with AM 1 M 2 (PO 4 ) 3 stoichiometry where the choice of "A" and "M" cation varies widely. This report, which de scribes substitutional derivatives of NZP (NaZr 2 P 3 O 12 ), summarizes the accomplishments of a Laboratory D irected Research and Development (LDRD) project to analyze transport mec hanisms using a combination of in situ studies of structure, composition, and bonding, com bined with first principles theory and modeling. We developed an experimental platform and applied methods, such as synchrotron- based X-ray spectroscopies, to probe the electronic structure of compositionally well-controlled NaSICON films while in operation ( i.e ., conducting Na ions exposed to oxygen or water va por atmospheres). First principles theory and modeling were used to interpret the experimental observations and develop an enhanced understanding of atomistic processes that give rise to, and affect, ion conduction.

  13. Porphyrin-silicon hybrid field-effect transistor with individually addressable top-gate structure.

    PubMed

    Seol, Myeong-Lok; Choi, Sung-Jin; Kim, Chang-Hoon; Moon, Dong-Il; Choi, Yang-Kyu

    2012-01-24

    A conductance-controllable hybrid device that utilizes the photoinduced charge transfer behavior of a porphyrin in a field-effect transistor (FET) with a nanogap is proposed and analyzed. A conventional metal-oxide-semiconductor (MOS) structure is modified to form a nanogap in which the porphyrin can be embedded. The conductance of an inversion channel is controlled by the negatively charged, optically activated porphyrin molecules. The proposed nanogap-formed MOSFET structure solves the conventional dilemma that a top-gate cannot be used for an organic-inorganic hybrid device because the top-gate blocks an entire area of a channel where organic material should be immobilized. The top-gate structure has much practicality compared with the back-gate structure because each device can be controlled individually. Furthermore, the device is highly compatible with the chip-based integrated system because the fabrication process follows the standard complementary metal-oxide-semiconductor (CMOS) technology. The charge transfer mechanisms between silicon and porphyrin are analyzed using devices with different doping polarities and geometrical parameters. The results show that the influence of the negative charge of the porphyrin in the device is reversed when opposite doping polarities are used. The device characteristics can be comprehensively evaluated using the energy band diagram analysis and simulation. The possible application of the proposed device for nonvolatile memory is demonstrated using the optical charging and electrical discharging behavior of the porphyrins.

  14. Porphyrin coordination polymer nanospheres and nanorods

    DOEpatents

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

    2013-09-10

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

  15. Porphyrin coordination polymer nanospheres and nanorods

    SciTech Connect

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

    2012-12-04

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

  16. Search for porphyrins in lunar dust.

    PubMed

    Hodgson, G W; Peterson, E; Kvenvolden, K A; Bunnenberg, E; Halpern, B; Ponnamperuma, C

    1970-01-30

    Evidence for porphyrins was obtained in the Apollo 11 bulk sample of lunar dust by fluorescence spectrometry and analytical demetallation. The indicated porphyrins showed major fluorescence excitation at 390 nanometers. Abundance was about 10(-10) gram of porphyrin per gram of dust. Similar pigments were found in exhaust products from tests of a lunar descent engine. The similarity of results suggests that most if not all of the indicated porphyrin aggregate of the lunar sample probably was synthesized from rocket fuel during the landing of the lunar module. These compounds may be the product of a novel high-temperature synthesis of cosmochemical interest.

  17. Controlling porphyrin nanoarchitectures at solid interfaces.

    PubMed

    Hill, Jonathan P; Xie, Yongshu; Akada, Misaho; Wakayama, Yutaka; Shrestha, Lok Kumar; Ji, Qingmin; Ariga, Katsuhiko

    2013-06-18

    Two complementary examples of porphyrin nanoarchitectonics are presented. The fabrication of binary molecular monolayers using two different porphyrin molecules, tetrakis(3,5-di-t-butyl-4-hydroxyphenyl)porphyrin (1) and tetrakis(4-pyridyl)porphyrin (2), by deposition in ultrahigh vacuum was demonstrated. Two unusual heteromolecular monolayer structures were observed, with one exhibiting good separation of 1 molecules within the monolayer. Also, a synthetic nanoarchitectonic approach was used to prepare self-assembled molecular nanowires at a mica substrate. The nanowires could be observed to grow using atomic force microscopy (AFM), and the network structures of the nanowires could be influenced by manipulation using the AFM probe tip.

  18. Orientation and dynamics of melittin in membranes of varying composition utilizing NBD fluorescence.

    PubMed

    Raghuraman, H; Chattopadhyay, Amitabha

    2007-02-15

    Melittin is a cationic hemolytic peptide isolated from the European honey bee, Apis mellifera. The organization of membrane-bound melittin has earlier been shown to be dependent on the physical state and composition of membranes. In this study, we covalently labeled the N-terminal (Gly-1) and Lys-7 of melittin with an environment-sensitive fluorescent probe, the NBD group, to monitor the influence of negatively charged lipids and cholesterol on the organization and dynamics of membrane-bound melittin. Our results show that the NBD group of melittin labeled at its N-terminal end does not exhibit red edge excitation shift in DOPC and DOPC/DOPG membranes, whereas the NBD group of melittin labeled at Lys-7 exhibits REES of approximately 8 nm. This could be attributed to difference in membrane microenvironment experienced by the NBD groups in these analogs. Interestingly, the membrane environment of the NBD groups is sensitive to the presence of cholesterol, which is supported by time-resolved fluorescence measurements. Importantly, the orientation of melittin is found to be parallel to the membrane surface as determined by membrane penetration depth analysis using the parallax method in all cases. Our results constitute the first report to our knowledge describing the orientation of melittin in cholesterol-containing membranes. These results assume significance in the overall context of the role of membrane lipids in the orientation and function of membrane proteins and peptides.

  19. Monitoring the organization and dynamics of bovine hippocampal membranes utilizing Laurdan generalized polarization.

    PubMed

    Mukherjee, Soumi; Chattopadhyay, Amitabha

    2005-08-01

    Organization and dynamics of cellular membranes in the nervous system are crucial for the function of neuronal membrane receptors. The lipid composition of neuronal cells is unique and has been correlated with the increased complexity in the organization of the nervous system during evolution. Previous work from our laboratory has established bovine hippocampal membranes as a convenient natural source for studying neuronal receptors such as the G-protein coupled serotonin1A receptor. In this paper, we have explored the organization and dynamics of bovine hippocampal membranes using the amphiphilic environment-sensitive fluorescent probe Laurdan. Our results show that the emission spectra of Laurdan display an additional red shifted peak as a function of increasing temperature in native as well as cholesterol-depleted membranes and liposomes made from lipid extracts of the native membrane. Interestingly, wavelength dependence of Laurdan generalized polarization (GP) in native membranes indicates the presence of an ordered gel-like phase at low temperatures, whereas characteristics of the liquid-ordered phase are observed at high temperatures. Similar experiments performed using cholesterol-depleted membranes show fluidization of the membrane with increasing cholesterol depletion. In addition, results from fluorescence polarization of DPH indicate that the hippocampal membrane is fairly ordered even at physiological temperature. The temperature dependence of Laurdan excitation GP provides a measure of the apparent thermal transition temperature and extent of cooperativity in these membranes. Analysis of time-resolved fluorescence measurements of Laurdan shows reduction in mean fluorescence lifetime with increasing temperature due to change in environmental polarity. These results constitute novel information on the dynamics of hippocampal membranes and its modulation by cholesterol depletion monitored using Laurdan fluorescence.

  20. Guided bone regeneration utilizing expanded polytetrafluoroethylene membranes in combination with submerged and nonsubmerged dental implants in beagle dogs.

    PubMed

    Fiorellini, J P; Engebretson, S P; Donath, K; Weber, H P

    1998-05-01

    Treatment of partial and total edentulism with submerged and nonsubmerged dental implants which follows the concept of osseointegration has become an accepted treatment modality. With compromised implant sites, practitioners have begun to combine one-stage implants with established techniques including guided bone regeneration. However, the clinical evaluation of this technique is limited. Therefore, the purpose of this study was to evaluate osseointegration and bone regeneration around nonsubmerged or submerged implants placed directly into surgically created osseous defects with or without expanded polytetrafluoroethylene (ePTFE) membranes. A total of 24 implants were placed in the mandibles of 4 beagle dogs and randomly assigned to 1 of 3 treatment groups. In group A, nonsubmerged implants were placed into osseous defects and treated with a poncho style ePTFE membrane. These membranes had a hole punched into the center and were slipped over the nonsubmerged implants. In group B, nonsubmerged implants were placed into osseous defects without an ePTFE membrane. In group C, submerged implants were placed into osseous defects and covered with an ePTFE membrane. Histometric measurements of each treatment group were made to determine percent bone gain or loss along the implant surface. Although a number of membrane removals occurred during the healing period, histological analysis indicated osseous ingrowth and osseointegration around nonsubmerged and submerged implants. An overall comparison of the treatment groups with ANOVA revealed that there were no significant differences between treatment groups, P > or = 0.05. However, when the data were stratified into sites which retained or lost the ePTFE membrane, the percent of bone regeneration was reduced in group A. Therefore, it may be recommended that nonsubmerged implants be placed with a submerged or "semi-submerged" protocol when utilized in conjunction with ePTFE membranes.

  1. Hierarchical cooperative binary ionic porphyrin nanocomposites.

    PubMed

    Tian, Yongming; Busani, Tito; Uyeda, Gregory H; Martin, Kathleen E; van Swol, Frank; Medforth, Craig J; Montaño, Gabriel A; Shelnutt, John A

    2012-05-18

    Cooperative binary ionic (CBI) solids comprise a versatile new class of opto-electronic and catalytic materials consisting of ionically self-assembled pairs of organic anions and cations. Herein, we report CBI nanocomposites formed by growing nanoparticles of one type of porphyrin CBI solid onto a second porphyrin CBI substructure with complementary functionality.

  2. Hybrids of cationic porphyrins with nanocarbons.

    PubMed

    Girek, Beata; Sliwa, Wanda

    In the review hybrids of cationic porphyrins (i.e. porphyrins functionalized by quaternary pyridinium groups) with nanocarbons such as fullerenes, carbon nanotubes and graphene are described. Selected examples of these species are characterized in regard of their properties and possible applications.

  3. Preparation of porphyrins and their metal complexes

    DOEpatents

    Ellis, Jr., Paul E.; Langdale, Wayne A.

    1997-01-01

    A hydroxyl-containing pyrrolic compound having a hydroxyl group or a hydroxyl-containing group in the 2-position, optionally substituted in the beta positions, is condensed in an acidified two immiscible phase solvent system to produce excellent yields of the corresponding porphyrin or metal porphyrin.

  4. Preparation of porphyrins and their metal complexes

    DOEpatents

    Ellis, P.E. Jr.; Langdale, W.A.

    1997-08-19

    A hydroxyl-containing pyrrolic compound having a hydroxyl group or a hydroxyl-containing group in the 2-position, optionally substituted in the beta positions, is condensed in an acidified two immiscible phase solvent system to produce excellent yields of the corresponding porphyrin or metal porphyrin.

  5. Assessing the utility of bipolar membranes for use in photoelectrochemical water-splitting cells.

    PubMed

    Vargas-Barbosa, Nella M; Geise, Geoffrey M; Hickner, Michael A; Mallouk, Thomas E

    2014-11-01

    Membranes are important in water-splitting solar cells because they prevent crossover of hydrogen and oxygen. Here, bipolar membranes (BPMs) were tested as separators in water electrolysis cells. Steady-state membrane and solution resistances, electrode overpotentials, and pH gradients were measured at current densities relevant to solar photoelectrolysis. Under forward bias conditions, electrodialysis of phosphate buffer ions creates a pH gradient across a BPM. Under reverse bias, the BPM can maintain a constant buffer pH on both sides of the cell, but a large membrane potential develops. Thus, the BPM does not present a viable solution for electrolysis in buffered electrolytes. However, the membrane potential is minimized when the anode and cathode compartments of the cell contain strongly basic and acidic electrolytes, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Syntheses and Functionalizations of Porphyrin Macrocycles

    PubMed Central

    Vicente, Maria da G.H.; Smith, Kevin M.

    2014-01-01

    Porphyrin macrocycles have been the subject of intense study in the last century because they are widely distributed in nature, usually as metal complexes of either iron or magnesium. As such, they serve as the prosthetic groups in a wide variety of primary metabolites, such as hemoglobins, myoglobins, cytochromes, catalases, peroxidases, chlorophylls, and bacteriochlorophylls; these compounds have multiple applications in materials science, biology and medicine. This article describes current methodology for preparation of simple, symmetrical model porphyrins, as well as more complex protocols for preparation of unsymmetrically substituted porphyrin macrocycles similar to those found in nature. The basic chemical reactivity of porphyrins and metalloporphyrin is also described, including electrophilic and nucleophilic reactions, oxidations, reductions, and metal-mediated cross-coupling reactions. Using the synthetic approaches and reactivity profiles presented, eventually almost any substituted porphyrin system can be prepared for applications in a variety of areas, including in catalysis, electron transport, model biological systems and therapeutics. PMID:25484638

  7. A novel ethacrynic acid sensor based on a lanthanide porphyrin complex in a PVC matrix.

    PubMed

    Zhang, X B; Guo, C C; Xu, J B; Shen, G L; Yu, R Q

    2000-05-01

    Lanthanide porphyrin complexes synthesized by a solid state method were used to prepare a novel ethacrynic acid (EA) sensor. The sensor, based on pentane-2,4-dionato(meso-tetraphenylporphinato)terbium [TbTPP(acac)] with an optimized membrane composition, exhibits a Nernstian response to EA- ion in the concentration range 7.4 x 10(-6)-1.0 x 10(-1) mol l-1 with a pH range from 3.2 to 6.8 and a fast response time of 30 s. The electrode shows improved selectivity towards EA- ion with respect to common co-existing ions compared with the previously reported EA sensor. As electroactive materials, lanthanide porphyrin complexes show better potentiometric response characteristics than copper porphyrin complexes. The effect of solvent mediators and lipophilic ion additives was studied and the experimental conditions were optimized. The electrode was applied to the determination of EA in human urine samples with satisfactory results.

  8. Photobactericidal porphyrin-cellulose nanocrystals: synthesis, characterization, and antimicrobial properties.

    PubMed

    Feese, Elke; Sadeghifar, Hasan; Gracz, Hanna S; Argyropoulos, Dimitris S; Ghiladi, Reza A

    2011-10-10

    Adherence and survival of pathogenic bacteria on surfaces leading to concomitant transmission to new hosts significantly contributes to the proliferation of pathogens, which in turn considerably increases the threat to human health, particularly by antibiotic-resistant bacteria. Consequently, more research into effective surface disinfection and alternative materials (fabrics, plastics, or coatings) with antimicrobial and other bioactive characteristics is desirable. This report describes the synthesis and characterization of cellulose nanocrystals that were surface-modified with a cationic porphyrin. The porphyrin was appended onto the cellulose surface via the Cu(I)-catalyzed Huisgen-Meldal-Sharpless 1,3-dipolar cycloaddition having occurred between azide groups on the cellulosic surface and porphyrinic alkynes. The resulting, generally insoluble, crystalline material, CNC-Por (5), was characterized by infrared and diffusion (1)H NMR spectroscopies, gel permeation chromatography, and thermogravimetric analysis. Although only suspended, and not dissolved, in an aqueous system, CNC-Por (5) showed excellent efficacy toward the photodynamic inactivation of Mycobacterium smegmatis and Staphylococcus aureus , albeit only slight activity against Escherichia coli . The synthesis, properties, and activity of CNC-Por (5) described herein serve as a benchmark toward our overall objectives of developing novel, potent, bioactive, photobactericidal materials that are effective against a range of bacteria, with potential utilization in the health care and food preparation industries.

  9. Optical acetylcholine sensor based on free base porphyrin as a chromoionophore.

    PubMed

    Mroczkiewicz, Monika; Pietrzak, Mariusz; Górski, Łukasz; Malinowska, Elżbieta

    2011-09-21

    In this work, the possibility of application of free base porphyrin as a lipophilic pH chromoionophore for the preparation of optical cation-selective sensors was investigated. The properties of polymeric membranes, containing porphyrins of different structures, namely tetraphenylporphyrin (TPP) and octaethylporphyrin (OEP), were compared. Changes in equilibrium between protonated and deprotonated form of porphyrin, resulting from variations in ACh concentration, were evaluated. The influence of various factors (kind and quantity of anionic additive and porphyrin in the membrane phase, pH of sample solution) on initial equilibrium was studied. The best membrane composition was chosen as: TPP 3 wt.%, KTFPB 175 mol.% relative to ionophore, PVC:o-NPOE (1 : 4) and measuring buffer solution: 0.05 M MES, pH 4.5. Selectivity, response stability, reversibility and repeatability tests were carried out for chosen sensor. Developed sensor allowed for the determination of a model analyte, acetylcholine, at the concentration range of 10(-5) to 10(-2) M, both in stationary and flow-injection system. Sensor response was reversible and repeatable in the mentioned concentration range.

  10. Photodynamic efficiency of cationic meso-porphyrins at lipid bilayers: insights from molecular dynamics simulations.

    PubMed

    Cordeiro, Rodrigo M; Miotto, Ronei; Baptista, Maurício S

    2012-12-20

    Porphyrin derivatives have applications as photoactive drugs in photodynamic therapy. However, little is known about their interactions with phospholipid membranes at the molecular level. We employed molecular dynamics simulations to model the binding between a series of cationic meso-(N-methyl-4-pyridinium)phenylporphyrins and anionic phosphatidylglycerol lipid bilayers. This was done in the presence of molecular oxygen within the membrane. The ability of various porphyrins to cause photodamage was quantified in terms of their immersion depth and degree of exposition to a higher oxygen concentration inside the membrane. Simulations showed that the photodynamic efficiency could be improved as the number of hydrophobic phenyl substituents attached to the porphyrinic ring increased. In the specific case of porphyrins containing two hydrophobic and two charged substituents, the cis isomer was significantly more efficient than the trans. These results correlate well with previous experimental observations. They highlight the importance of both the total charge and amphiphilicity of the photosensitizer for its performance in photodynamic therapy.

  11. Utilization of Shrimp Skin Waste (Sea Lobster) As Raw Material for the Membrane Filtration

    NASA Astrophysics Data System (ADS)

    Nyoman Rupiasih, Ni; Sumadiyasa, Made; Suyanto, Hery; Windari, Putri

    2017-05-01

    In view of the increasing littering of the sea banks by shells of crustaceans, a study was carried out to investigate the extraction and characterization of chitosan from skin waste of sea lobster i.e. ‘Bamboo Lobster’ (Panulirus versicolor). Chitosan was extracted using conventional methods such as pretreatment, demineralization, deprotienization, and deacetylation. The result showed that the degree of deacetylation of chitosan obtained is 70.02%. The FTIR spectra of the chitosan gave a characteristic of -NH2 band at 3447 cm-1 and carbonyl group band at 1655 cm-1. This chitosan has been used to prepare membrane. The chitosan membrane 2% has been prepared using phase inversion method with precipitation by solvent evaporation. The membranes were characterized by FTIR spectrophotometer, Nova 1200e using BJH method, and filtration method. The results show that thickness of the membrane is about 134 μm. The FTIR spectra show that functional groups present in the membrane are -NH, -CH, C=O, and -OH. Using BJH method obtained that the pore diameter is 3.382 nm with pore density is 8.95 x 105 pores/m3. By filtration method obtained that pure water flux (PWF) of the membrane are 386.662 and 489.627 1/m2.h at pressure 80-85 kPa and 90-100 kPa, respectively. These results show that skin waste of sea lobster was discovered as a raw material to prepare chitosan membrane. The membrane obtained is belonged to mesoporous group which may use in microfiltration process.

  12. Novel drug delivery strategies for porphyrins and porphyrin precursors

    NASA Astrophysics Data System (ADS)

    Morrow, D. I. J.; Donnelly, R. F.

    2009-06-01

    superficial lesions, such as actinic keratosis. In addition, photodynamic antimicrobial chemotherapy (PACT) is attracting increasing interest for the treatment of infection. However, delivery strategies for topical PDT and PACT are still based on application of rather simplistic cream and solution formulations, with little consideration given to thermodynamics, targeting or the physicochemical properties of the active agent. Purpose-designed dosage forms for topical delivery of aminolevulinic acid or its esters include creams containing penetration enhancers and/or iron chelators, pressure sensitive patches and bioadhesive patches. Such systems aim to enhance drug delivery across the stratum corneum and keratinised debris overlying neoplastic lesions and improve subsequent protoporphyrin IX (PpIX) production. The alternative to using porphyrin precursors is the use of pre-formed photosensitisers. However, owing to their relatively high molecular weights, conventional topical application is not appropriate. Innovative strategies, such as the use of needle-free injections and microneedle arrays, bypass the stratum corneum, enabling rapid and targeted delivery not only porphyrin precursors but also pre-formed photosensitisers. This presentation will review drug delivery work published to date in the fields of PDT and PACT. In addition, the benefits of employing the latest advances in pharmaceutical technology will be highlighted.

  13. Photoinitiated destruction of composite porphyrin-protein polymersomes.

    PubMed

    Robbins, Gregory P; Jimbo, Masaya; Swift, Joe; Therien, Michael J; Hammer, Daniel A; Dmochowski, Ivan J

    2009-03-25

    Bilayer vesicles assembled from amphiphilic diblock copolymers (polymersomes) adopt asymmetric structures when loaded with moderate concentrations (>or=1.5 mg/mL) of horse spleen ferritin (HSF) or its iron-free variant (HSAF). Incorporation of both ferritin and a zinc porphyrin dimer (PZn(2)) generates photoresponsive vesicles: irradiation with focused light of near-UV to near-IR wavelengths induces polymersome deformation and destruction on the minute time scale. To investigate this phenomenon, polymersomes were loaded with dye-labeled ferritin and PZn(2). Confocal microscopy identified BODIPY-FL-labeled ferritin at the membrane, whereas Cy3-labeled ferritin was found both at the membrane and throughout the aqueous core. Fluorescence recovery after photobleaching (FRAP) experiments confirmed that Cy3- and BODIPY-FL-labeled ferritin and PZn(2) exhibited slow diffusion at the membrane, consistent with membrane association. Furthermore, micropipette aspiration experiments revealed increased elastic moduli and altered bending rigidity in vesicles incorporating HSAF. Finally, a small molecule (biocytin) was encapsulated within the ferritin-PZn(2) vesicles and released upon exposure to light. These data indicate synergy between ferritin, whose membrane association lowers the barrier to deformation, and PZn(2), which embeds in the membrane, harvests light energy and produces local heating that may lead to membrane budding. This appears to be a general protein-polymer membrane phenomenon, as replacement of ferritin with bovine serum albumin or equine skeletal myoglobin resulted in vesicles with similar asymmetric morphology and photosensitivity.

  14. Highly carbonylated cellulose nanofibrous membranes utilizing maleic anhydride grafting for efficient lysozyme adsorption.

    PubMed

    Ma, Juncheng; Wang, Xueqin; Fu, Qiuxia; Si, Yang; Yu, Jianyong; Ding, Bin

    2015-07-22

    Construction of adsorptive materials for simple, efficient, and high-throughput adsorption of proteins is critical to meet the great demands of highly purified proteins in biotechnological and biopharmaceutical industry; however, it has proven extremely challenging. Here, we report a cost-effective strategy to create carbonyl groups surface-functionalized nanofibrous membranes under mild conditions for positively charged protein adsorption. Our approach allows maleic anhydride to in situ graft on cellulose nanofibrous membranes (CMA) to construct adsorptive membranes with large surface area and tortuous porous structure. Thereby, the resultant CMA membranes exhibited high adsorption capacity of 160 mg g(-1), fast equilibrium within 12 h, and good reversibility to lysozyme. Moreover, the dynamic adsorption was performed under low pressure-drops (750 Pa), with a relatively high saturation adsorption amount of 118 mg g(-1), which matched well with the requirements for proteins purification. Considering the excellent adsorption performance of the as-prepared adsorptive membranes, this simple and intriguing approach may pave a way for the design and development of robust and cost-effective adsorption membranes to meet the great demands for fast and efficient adsorption of positively charged proteins.

  15. Two-step Mechanochemical Synthesis of Porphyrins

    PubMed Central

    Shy, Hannah; Mackin, Paula; Orvieto, Andrea S.; Gharbharan, Deepa; Peterson, Geneva R.; Bampos, Nick; Hamilton, Tamara D.

    2014-01-01

    Porphyrin synthesis under solvent-free conditions represents the “greening” of a traditional synthesis that normally requires large amounts of organic solvent, and has hindered industrial-scale synthesis of this useful class of molecules. We have found that the four-fold acid-catalysed condensation of aldehyde and pyrrole to yield a tetra-substituted porphyrin is possible through mechanochemical techniques, without a solvent present. This represents one of the still-rare examples of carbon-carbon bond formation by mechanochemistry. Specifically, upon grinding equimolar amounts of pyrrole and benzaldehyde in presence of an acid catalyst, cyclization takes place to give reduced porphyrin precursors (reversible), which upon oxidation form tetraphenylporphyrin (TPP). The approach has been found suitable for synthesis of a variety of meso-tetrasubstituted porphyrins. Oxidation can occur either by using an oxidizing agent in solution, to give yields comparable to those published for traditional methods of porphyrin synthesis, or through mechanochemical means resulting in a two-step mechanochemical synthesis to give slightly lower yields that are still being optimized. We are also working on “green” methods of porphyrin isolation, including entrainment sublimation, which would hopefully further reduce the need for large amounts of organic solvent. These results hold promise for the development of mechanochemical synthetic protocols for porphyrins and related classes of compounds. PMID:25406483

  16. Smaragdyrins: emeralds of expanded porphyrin family.

    PubMed

    Pareek, Yogita; Ravikanth, M; Chandrashekar, T K

    2012-10-16

    Porphyrins are tetrapyrrolic 18 π electron conjugated macrocycles with wide applications that range from materials to medicine. Expanded porphyrins, synthetic analogues of porphyrins that contain more than 18 π electrons in the conjugated pathway, have an increased number of pyrroles or other heterocyles or multiple meso-carbon bridges. The expanded porphyrins have attracted tremendous attention because of unique features such as anion binding or transport that are not present in porphyrins. Expanded porphyrins exhibit wide applications that include their use in the coordination of large metal ions, as contrasting agents in magnetic resonance imaging (MRI), as sensitizers for photodynamic therapy (PDT) and as materials for nonlinear optical (NLO) studies. Pentaphyrin 1, sapphyrin 2, and smaragdyrin 3 are expanded porphyrins that include five pyrroles or heterocyclic rings. They differ from each other in the number of bridging carbons and direct bonds that connect the five heterocyclic rings. Sapphyrins were the first stable expanded porphyrins reported in the literature and remain one of the most extensively studied macrocycles. The strategies used to synthesize sapphyrins are well established, and these macrocycles are versatile anion binding agents. They possess rich porphyrin-like coordination chemistry and have been used in diverse applications. This Account reviews developments in smaragdyrin chemistry. Although smaragdyrins were discovered at the same time as sapphyrins, the chemistry of smaragdyrins remained underdeveloped because of synthetic difficulties and their comparative instability. Earlier efforts resulted in the isolation of stable β-substituted smaragdyrins and meso-aryl isosmaragdyrins. Recently, researchers have synthesized stable meso-aryl smaragdyrins by [3 + 2] oxidative coupling reactions. These results have stimulated renewed research interest in the exploration of these compounds for anion and cation binding, energy transfer

  17. Highlighting nuclear membrane staining in thyroid neoplasms with emerin: review and diagnostic utility.

    PubMed

    Kinsella, Mary D; Hinrichs, Benjamin; Cohen, Cynthia; Siddiqui, Momin T

    2013-06-01

    Immunohistochemical staining (IHC) with emerin, an integral inner nuclear membrane protein, highlights nuclear membrane details in papillary thyroid carcinoma (PTC). We evaluated emerin for highlighting nuclear shape, grooves, inclusions, circumferential nuclear membrane irregularities ("garlands"), deep "stellate" membrane invaginations, and crescents in 34 fine-needle aspiration (FNA) cell blocks, PTC (n = 24) and follicular neoplasms (FN) (n = 10). Tissue microarrays were also examined for 182 cases, PTC (n = 95) and non-PTC (n = 87). Emerin IHC of PTC revealed a predominantly oval nuclear shape in the majority of cases, with FN demonstrating round nuclei and FV of PTC showing a roughly equal distribution of round and oval shapes. In addition to oval nuclear shape, the presence of emerin-positive nuclear grooves, circumferential emerin nuclear "garlands," nuclear crescent shapes, and chromatin clearing on cell block H&E staining were significant predictors of PTC by regression analysis. Emerin IHC of thyroid FNA and surgical specimens serves as a useful adjunct to conventional H&E staining in the diagnosis of PTC and its distinction from FN by delineating diagnostic nuclear membrane irregularities ("garlands" and crescents), nuclear grooves, and a characteristic oval nuclear shape. In diagnostically challenging cases with limited cellularity, emerin staining can help to provide a more definitive diagnosis of PTC.

  18. Novel porphyrin-psoralen conjugates: synthesis, DNA interaction and cytotoxicity studies.

    PubMed

    Kumar, Dalip; Mishra, Bhupendra A; Chandra Shekar, K P; Kumar, Anil; Akamatsu, Kanako; Kurihara, Ryohsuke; Ito, Takeo

    2013-10-21

    A Cu(i)-catalyzed azide-alkyne cycloaddition reaction (CuAAC) has been utilized to prepare novel triazole-linked cationic porphyrin-psoralen conjugates that exhibited significant photocytotoxicity against A549 cancer cells (IC50 = 84 nM).

  19. Fluorescent sensor for imidazole derivatives based on monomer-dimer equilibrium of a zinc porphyrin complex in a polymeric film.

    PubMed

    Zhang, Ying; Yang, Ronghua; Liu, Feng; Li, Ke'an

    2004-12-15

    A new zinc(II) porphyrin conjugate with an appended pyrene subunit has been synthesized and shown to exhibit significant and analytical usefulness for fluorescence sensing toward imidazole derivatives. The molecular recognition was based on the bridging interaction of the imidazole ring of analyte with the zinc(II) center of the porphyrin, while the transduction signal for the recognition process was the pyrene excimer fluorescence. The sensor was constructed and applied for fluorescence assay of histidine in aqueous solution by immobilizing the sensing material in a plasticized PVC membrane. When the membrane was bathed in an alkaline solution void of histidine, zinc(II) porphyrin was present in the monomer form, and pyrene emitted monomer fluorescence at 378 and 397 nm. With the presence of histidine in the sample solution, histidine was extracted into the membrane phase and bridged with the Zn(II) center of the porphyrin, causing the monomer porphyrin to be converted to its dimeric species. Since the formation of porphyrin dimer was accompanied by the enhancement of pyrene excimer emission at 454 nm, the chemical recognition process could be directly translated into a fluorescent signal. With the optode membrane M1 described, histidine in sample solution from 6.76 x 10(-7) to 5.01 x 10(-3) M can be determined. The limit of detection was 1.34 x 10(-7) M. The optical selectivity coefficient obtained for histidine over biologically relevant amino acids and anions met the selectivity requirements for the determination of histidine in biological samples. Serum histidine values obtained by the optode membrane fell in the normal range of the content reported in the literature and were in good agreement with those obtained by HPLC.

  20. Unique Diagnostic and Therapeutic Roles of Porphyrins and Phthalocyanines in Photodynamic Therapy, Imaging and Theranostics

    PubMed Central

    Josefsen, Leanne B.; Boyle, Ross W.

    2012-01-01

    Porphyrinic molecules have a unique theranostic role in disease therapy; they have been used to image, detect and treat different forms of diseased tissue including age-related macular degeneration and a number of different cancer types. Current focus is on the clinical imaging of tumour tissue; targeted delivery of photosensitisers and the potential of photosensitisers in multimodal biomedical theranostic nanoplatforms. The roles of porphyrinic molecules in imaging and pdt, along with research into improving their selective uptake in diseased tissue and their utility in theranostic applications are highlighted in this Review. PMID:23082103

  1. Guided tissue regeneration-based root coverage utilizing collagen membranes: technique and case reports.

    PubMed

    Wang, Hom-Lay; Al-Shammari, Khalaf F

    2002-01-01

    Gingival recession defects have traditionally been treated with various grafting procedures. Recently, guided tissue regeneration with collagen membranes has shown promising results. This article reviews the rationale, indications, contraindications, and clinical methods for the use of bioabsorbable collagen membrane barriers. Several properties make collagen membranes attractive candidates for use as barriers in guided tissue regeneration-based root coverage procedures. These include the inhibition of epithelial migration and promotion of new connective tissue attachment; the ability to aggregate platelets, thereby facilitating wound stabilization and maturation; the promotion of cellular migration and wound closure; the elimination of the need for reentry surgery; and the ability to augment tissue thickness. Cases are presented to illustrate the surgical principles and techniques.

  2. Utility of human amniotic membrane allograft in re-epithelialization of the nasal tip

    PubMed Central

    Dennis, D'Antonio C.; Turnock, Adam R.; Sutton, Collin; Chastant, Bradley; Vanderlan, Wesley B.

    2016-01-01

    Variations in skin thickness and contours pose significant challenges to reconstruction of the lower third of the nose. Human amniotic membrane allograft offers a potential alternative to tissue transfer in reconstruction of the lower third of the nose. We reviewed the procedure and photographs of a healthy 56-year-old male with a 22 × 18 mm lower third nasal defect involving full thickness skin and subcutaneous tissue. Following preparation for grafting, dehydrated human amniotic membrane was fashioned to the dimensions of the defect and applied. No further surgical intervention was provided for 3 months. Complete re-epithelialization of the nasal and adjacent defects was achieved with minimal scar formation. Human amniotic membrane allograft provides an efficacious and cosmetically acceptable alternative to local and regional tissue transfer.

  3. Crystal engineering of porphyrin framework solids.

    PubMed

    Goldberg, Israel

    2005-03-14

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

  4. Porphyrin-aminoquinoline conjugates as telomerase inhibitors.

    PubMed

    Maraval, Alexandrine; Franco, Sonia; Vialas, Corine; Pratviel, Geneviève; Blasco, Maria A; Meunier, Bernard

    2003-03-21

    A series of metalloporphyrins was prepared in order to target the G-quadruplex structure of telomeric DNA for the design of antitelomerase compounds. The initial cationic tetramethylpyridiniumyl porphyrin was modified by the replacement of one or two methylpyridiniumyl groups by one or two 4-aminoquinoline moieties, at the meso position, in order to increase the cell penetration and the quadruplex affinity. The porphyrins were either metallated by manganese or by nickel. The degradation of quadruplex DNA was assayed in vitro with the manganese redox-active derivatives. All porphyrins complexes were capable of inhibiting the telomerase enzyme with IC50 values in the micromolar range (TRAP assay).

  5. Nickel porphyrins for memory optical applications

    DOEpatents

    Shelnutt, John A.; Jia, Songling; Medforth, Craig; Holten, Dewey; Nelson, Nora Y.; Smith, Kevin M.

    2000-01-01

    The present invention relates to a nickel-porphyrin derivative in a matrix, the nickel-porphyrin derivative comprising at least two conformational isomers, a lower-energy-state conformer and a higher-energy-state conformer, such that when the higher-energy-state conformer is generated from the lower-energy-state conformer following absorption of a photon of suitable energy, the time to return to the lower-energy-state conformer is greater than 40 nanoseconds at approximately room temperature. The nickel-porphyrin derivative is useful in optical memory applications.

  6. Transition Metal Complexes of Expanded Porphyrins

    PubMed Central

    Sessler, Jonathan L.; Tomat, Elisa

    2008-01-01

    Over the last two decades, the rapid development of new synthetic routes for the preparation of expanded porphyrin macrocycles has allowed exploration of a new frontier consisting of “porphyrin-like” coordination chemistry. In this Account, we summarize our exploratory forays into the still relatively poorly explored area of oligopyrrolic macrocycle metalation chemistry. Specifically, we describe our successful formation of both mono- and binuclear complexes and in doing so highlight the diversity of coordination modes available to expanded porphyrin-type ligands. The nature of the inserted cation, the emerging role of tautomeric equilibria, and the importance of hydrogen-bonding interactions in regulating this chemistry are also discussed. PMID:17397134

  7. Utilization of monensin for detection of microdomains in cholesterol containing membrane.

    PubMed

    Bransburg-Zabary, S; Nachliel, E; Gutman, M

    1996-12-04

    The effect of cholesterol on the monensin mediated proton-cation exchange reaction was measured in the time-resolved domain. The experimental system consisted of a black lipid membrane equilibrated with monensin (Nachliel, E., Finkelstein, Y. and Gutman, M. (1996) Biochim. Biophys. Acta 1285, 131-145). The membrane separated two compartments containing electrolyte solutions and pyranine (8-hydroxypyrene 1,3,6-trisulfonate) was added on to one side of the membrane. A short laser pulse was used to cause a brief transient acidification of the pyranine-containing solution and the resulting electric signal, derived from proton-cation exchange, was measured in the microsecond time domain. Incorporation of cholesterol had a clear effect on the electric transients as measured with Na+ or K+ as transportable cations. The measured transients were subjected to rigorous analysis based on numeric integration of coupled, non-linear, differential rate equations which correspond with the perturbed multi-equilibria state between all reactants present in the system. The various kinetic parameters of the reaction and their dependence on the cholesterol content had been determined. On the basis of these observations we can draw the following conclusions: (1) Cholesterol perturbed the homogeneity of the membrane and microdomains were formed, having a composition that differed from the average value. The ionophore was found in domains which were practically depleted of phosphatidylserine. (2) The diffusivity of the protonated monensin (MoH) was not affected by the presence of cholesterol, indicating that the viscosity of the central layer of the membrane was unaltered. (3) The diffusivity of the monensin metal complexes (MoNa and MoK) was significantly increased upon addition of cholesterol. As the viscosity along the cross membranal diffusion route is unchanged, the enhanced motion of the MoNa and MoK is attributed to variations of the electrostatic potential within the domains.

  8. Oxoferryl porphyrin/hydrogen peroxide system whose behavior is equivalent to hydroperoxoferric porphyrin.

    PubMed

    Kitagishi, Hiroaki; Tamaki, Mariko; Ueda, Takunori; Hirota, Shun; Ohta, Takehiro; Naruta, Yoshinori; Kano, Koji

    2010-12-01

    The reaction between H(2)O(2) and a pyridine-coordinated ferric porphyrin encapsulated by a cyclodextrin dimer yielded a hydroperoxoferric porphyrin intermediate, PFe(III)-OOH, which rapidly decomposed to oxoferryl porphyrin (PFe(IV)═O). Upon reaction with H(2)O(2), PFe(IV)═O reverted to PFe(III)-OOH, which was converted to carbon monoxide-coordinated ferrous porphyrin under a CO atmosphere. PFe(IV)═O in the presence of excess H(2)O(2) behaves as PFe(III)-OOH.

  9. Conceptual design and analysis of a large antenna utilizing electrostatic membrane management

    NASA Technical Reports Server (NTRS)

    Brooks, A. L.; Coyner, J. V.; Gardner, W. J.; Mihora, D. J.

    1982-01-01

    Conceptual designs and associated technologies for deployment 100 m class radiometer antennas were developed. An electrostatically suspended and controlled membrane mirror and the supporting structure are discussed. The integrated spacecraft including STS cargo bay stowage and development were analyzed. An antenna performance evaluation was performed as a measure of the quality of the membrane/spacecraft when used as a radiometer in the 1 GHz to 5 GHz region. Several related LSS structural dynamic models differing by their stiffness property (and therefore, lowest modal frequencies) are reported. Control system whose complexity varies inversely with increasing modal frequency regimes are also reported. Interactive computer-aided-design software is discussed.

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

    PubMed

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

    2016-07-01

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

  11. TonB-Dependent outer-membrane proteins and siderophore utilization in Pseudomonas fluorescens Pf-5

    USDA-ARS?s Scientific Manuscript database

    The soil bacterium Pseudomonas fluorescens Pf-5 produces two siderophores, a pyoverdine and enantio-pyochelin, and its proteome includes 45 TonB-dependent outer-membrane proteins, which commonly function in uptake of siderophores and other substrates from the environment. The 45 proteins share the ...

  12. Photoluminescence of polydiacetylene membranes on porous silicon utilized for chemical sensors

    NASA Astrophysics Data System (ADS)

    Sabatani, Eyal; Kalisky, Yehoshua; Berman, Amir; Golan, Yuval; Gutman, Nadav; Urbach, Benayahu; Sa'ar, Amir

    2008-07-01

    Langmuir-Blodgett (LB) films of the conjugated polydiacetylene (PDA) exhibit spectroscopic behavior, which is dependent on the type of the supporting substrate. While on polished silicon surfaces the photoluminescence (PL) of PDA is quenched, it is preserved on top of 2D patterned macro-porous silicon (2D-MPS). 2D-MPS, prepared by electrochemical etching of photo-lithographically pre-patterned silicon, is a 2D array of ca. 10 μm deep pores with lateral 2-4 μm repeating unit cells in orthogonal or hexagonal arrangements. LB films of PDA on such surfaces form membranes with continuous domains of the size sufficient to cover laterally many cell units. Apparently, the PL from this film results exclusively from the portion of the PDA membrane which is suspended over pore openings, while portions of the film which are attached to the silicon on top of the pores walls does not exhibit PL at all. We have used these membranes in different configurations and exposed them to different chemical and biological agents and followed the PL intensity change. This report demonstrates the effectiveness of the combined system: LB films of PDA on top of 2D-MPS as sensing probe for a variety of chemicals including, Cd ions and TNT explosives. In addition, the use of films of PDA, in which glycol-lipid were embedded, for binding and recognition of lectin protein, mimicking the cell membrane interaction with its environment, is also demonstrated.

  13. Triiodothyronine facilitates weaning from extracorporeal membrane oxygenation by improved mitochondrial substrate utilization

    SciTech Connect

    Files, Matthew D.; Kajimoto, Masaki; Priddy, Colleen M.; Ledee, Dolena R.; Xu, Chun; Des Rosiers, Christine; Isern, Nancy G.; Portman, Michael A.

    2014-03-20

    Extracorporeal membrane oxygenation (ECMO) provides a bridge to recovery after myocardial injury in infants and children, yet morbidity and mortality remain high. Weaning from the circuit requires adequate cardiac contractile function, which can be impaired by metabolic disturbances induced either by ischemia-reperfusion and / or by ECMO.

  14. Synthesis of superamphiphobic breathable membranes utilizing SiO2 nanoparticles decorated fluorinated polyurethane nanofibers

    NASA Astrophysics Data System (ADS)

    Wang, Jialin; Raza, Aikifa; Si, Yang; Cui, Lingxiao; Ge, Jianfeng; Ding, Bin; Yu, Jianyong

    2012-11-01

    Superamphiphobic nanofibrous membranes exhibiting robust water/oil proof and breathable performances were prepared by the combination of a novel synthesized fluorinated polyurethane (FPU) containing a terminal perfluoroalkane segment and incorporated SiO2 nanoparticles (SiO2 NPs). By employing the FPU/SiO2 NPs incorporation, the hybrid membranes possess superhydrophobicity with a water contact angle of 165° and superoleophobicity with an oil contact angle of 151°. Surface morphological studies have indicated that the wettability of resultant membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. The quantitative hierarchical roughness analysis using N2 adsorption method has confirmed a major contribution of SiO2 NPs on enhancing the porous structure, and a detailed correlation between the fractal dimension and amphiphobicity is proposed. Furthermore, a designed concept test shows that the as-prepared membranes could load 1.5 kg water or oil at the same time maintained an extremely high air permeability of 2 L min-1, suggesting their use as promising materials for a variety of potential applications in protective clothing, bioseparation, water purification, tissue engineering, microfluidic systems, etc., and also provided new insight into the design and development of functional hybrid membranes based on FPU.Superamphiphobic nanofibrous membranes exhibiting robust water/oil proof and breathable performances were prepared by the combination of a novel synthesized fluorinated polyurethane (FPU) containing a terminal perfluoroalkane segment and incorporated SiO2 nanoparticles (SiO2 NPs). By employing the FPU/SiO2 NPs incorporation, the hybrid membranes possess superhydrophobicity with a water contact angle of 165° and superoleophobicity with an oil contact angle of 151°. Surface morphological studies have indicated that the wettability of resultant membranes could be manipulated by tuning the surface composition as

  15. Porphyrins as Catalysts in Scalable Organic Reactions.

    PubMed

    Barona-Castaño, Juan C; Carmona-Vargas, Christian C; Brocksom, Timothy J; de Oliveira, Kleber T

    2016-03-08

    Catalysis is a topic of continuous interest since it was discovered in chemistry centuries ago. Aiming at the advance of reactions for efficient processes, a number of approaches have been developed over the last 180 years, and more recently, porphyrins occupy an important role in this field. Porphyrins and metalloporphyrins are fascinating compounds which are involved in a number of synthetic transformations of great interest for industry and academy. The aim of this review is to cover the most recent progress in reactions catalysed by porphyrins in scalable procedures, thus presenting the state of the art in reactions of epoxidation, sulfoxidation, oxidation of alcohols to carbonyl compounds and C-H functionalization. In addition, the use of porphyrins as photocatalysts in continuous flow processes is covered.

  16. Porphyrin-Based Nanostructures for Photocatalytic Applications

    PubMed Central

    Chen, Yingzhi; Li, Aoxiang; Huang, Zheng-Hong; Wang, Lu-Ning; Kang, Feiyu

    2016-01-01

    Well-defined organic nanostructures with controllable size and morphology are increasingly exploited in optoelectronic devices. As promising building blocks, porphyrins have demonstrated great potentials in visible-light photocatalytic applications, because of their electrical, optical and catalytic properties. From this perspective, we have summarized the recent significant advances on the design and photocatalytic applications of porphyrin-based nanostructures. The rational strategies, such as texture or crystal modification and interfacial heterostructuring, are described. The applications of the porphyrin-based nanostructures in photocatalytic pollutant degradation and hydrogen evolution are presented. Finally, the ongoing challenges and opportunities for the future development of porphyrin nanostructures in high-quality nanodevices are also proposed. PMID:28344308

  17. Emerging applications of porphyrins in photomedicine

    PubMed Central

    Huang, Haoyuan; Song, Wentao; Rieffel, James

    2017-01-01

    Biomedical applications of porphyrins and related molecules have been extensively pursued in the context of photodynamic therapy. Recent advances in nanoscale engineering have opened the door for new ways that porphyrins stand to potentially benefit human health. Metalloporphyrins are inherently suitable for many types of medical imaging and therapy. Traditional nanocarriers such as liposomes, dendrimers and silica nanoparticles have been explored for photosensitizer delivery. Concurrently, entirely new classes of porphyrin nanostructures are being developed, such as smart materials that are activated by specific biochemicals encountered at disease sites. Techniques have been developed that improve treatments by combining biomaterials with photosensitizers and functional moieties such as peptides, DNA and antibodies. Compared to simpler structures, these more complex and functional designs can potentially decrease side effects and lead to safer and more efficient phototherapies. This review examines recent research on porphyrin-derived materials in multimodal imaging, drug delivery, bio-sensing, phototherapy and probe design, demonstrating their bright future for biomedical applications. PMID:28553633

  18. GUN4-Porphyrin Complexes Bind the ChlH/GUN5 Subunit of Mg-Chelatase and Promote Chlorophyll Biosynthesis in Arabidopsis[W

    PubMed Central

    Adhikari, Neil D.; Froehlich, John E.; Strand, Deserah D.; Buck, Stephanie M.; Kramer, David M.; Larkin, Robert M.

    2011-01-01

    The GENOMES UNCOUPLED4 (GUN4) protein stimulates chlorophyll biosynthesis by activating Mg-chelatase, the enzyme that commits protoporphyrin IX to chlorophyll biosynthesis. This stimulation depends on GUN4 binding the ChlH subunit of Mg-chelatase and the porphyrin substrate and product of Mg-chelatase. After binding porphyrins, GUN4 associates more stably with chloroplast membranes and was proposed to promote interactions between ChlH and chloroplast membranes—the site of Mg-chelatase activity. GUN4 was also proposed to attenuate the production of reactive oxygen species (ROS) by binding and shielding light-exposed porphyrins from collisions with O2. To test these proposals, we first engineered Arabidopsis thaliana plants that express only porphyrin binding–deficient forms of GUN4. Using these transgenic plants and particular mutants, we found that the porphyrin binding activity of GUN4 and Mg-chelatase contribute to the accumulation of chlorophyll, GUN4, and Mg-chelatase subunits. Also, we found that the porphyrin binding activity of GUN4 and Mg-chelatase affect the associations of GUN4 and ChlH with chloroplast membranes and have various effects on the expression of ROS-inducible genes. Based on our findings, we conclude that ChlH and GUN4 use distinct mechanisms to associate with chloroplast membranes and that mutant alleles of GUN4 and Mg-chelatase genes cause sensitivity to intense light by a mechanism that is potentially complex. PMID:21467578

  19. Porphyrin-loaded nanoparticles for cancer theranostics

    NASA Astrophysics Data System (ADS)

    Zhou, Yiming; Liang, Xiaolong; Dai, Zhifei

    2016-06-01

    Porphyrins have been used as pioneering theranostic agents not only for the photodynamic therapy, sonodynamic therapy and radiotherapy of cancer, but also for diagnostic fluorescence imaging, magnetic resonance imaging and photoacoustic imaging. A variety of porphyrins have been developed but very few of them have actually been employed in clinical trials due to their poor selectivity to tumorous tissue and high accumulation rates in the skin. In addition, most porphyrin molecules are hydrophobic and form aggregates in aqueous media. Nevertheless, the use of nanoparticles as porphyrin carriers shows great promise to overcome these shortcomings. Encapsulating or attaching porphyrins to nanoparticles makes them more suitable for tissue delivery because we can create materials with a conveniently specific tissue lifetime, specific targeting, immune tolerance, and hydrophilicity as well as other characteristics through rational design. In addition, various functional components (e.g. for targeting, imaging or therapeutic functions) can be easily introduced into a single nanoparticle platform for cancer theranostics. This review presents the current state of knowledge on porphyrin-loaded nanoparticles for the interwined imaging and therapy of cancer. The future trends and limitations of prophyrin-loaded nanoparticles are also outlined.

  20. Electron Transport through Porphyrin Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Zhou, Qi

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

  1. Ultrafast energy relaxation dynamics of directly linked porphyrin arrays

    SciTech Connect

    Cho, H.S.; Song, N.W.; Kim, Y.H.; Jeoung, S.C.; Hahn, S.; Kim, D.; Kim, S.K.; Yoshida, Naoya; Osuka, Atsuhiro

    2000-04-20

    A variety of porphyrin arrays connected together with different linkage were devised for possible applications to molecular optoelectronic devices such as wires, logic gates, and artificial light-harvesting arrays, etc. It has been relatively well established that the light signal transmission in these molecular assemblies is based on exciton migration process, which possibly gives rise to the structural changes during the exciton delocalization process. Zinc(II) 5,15-di(3,5-di-tert-butylphenyl)porphyrin (Z1), its directly meso,meso-linked porphyrin dimer (Z2), trimer (Z3), and tetramer (Z4) were synthesized with the goal to elucidate the relationship between exciton migration and structural change upon photoexcitation. One of the most important factors in structural changes for these porphyrin arrays is mainly determined by the dihedral angle between adjacent porphyrin moieties. For a systematic approach toward the investigation of the exciton coupling dynamics influenced by the relative orientation between neighboring porphyrin molecules, various time-resolved spectroscopic techniques such as fluorescence decay and transient absorption measurements with different polarization in pump/probe beams have been utilized. The steady-state excitation anisotropy spectra of Z2, Z3, and Z4 porphyrin arrays show that the photoexcitation of the high-energy exciton Soret band induces a large angle change between absorption and emission dipoles in contrast with the photoexcitation of the low-energy exciton split Soret and Q-bands. In the order of Z1, Z2, Z3, and Z4, their S{sub 1} states decay faster because of the increasing energy dissipation processes into a larger number of accessible states. In contrast, the rotational diffusion rates become slower in the same order because the overall molecular shape is elongated along the long axis of the molecular arrays, which experiences a large displacement of solvent molecules in rotational diffusion motion. Ultrafast fluorescence

  2. From thioether substituted porphyrins to sulfur linked porphyrin dimers: an unusual SNAr via thiolate displacement?

    PubMed

    Ryan, Aoife A; Plunkett, Shane; Casey, Aoife; McCabe, Thomas; Senge, Mathias O

    2014-01-11

    Treatment of meso 2-ethylhexyl-3-mercaptopropionate substituted porphyrins with base at room temperature generated a porphyrin thiolate anion which in situ reacted in a nucleophilic aromatic substitution (SNAr) reaction with remaining thioether derivative. This reaction yielded S-linked bisporphyrins in good yields, with mechanistic insight obtained via displacement reactions. Additionally, SNAr of the thioether chain was achieved using S- and organolithium nucleophiles.

  3. Towards multielectron photocatalysis: a porphyrin array for lateral hole transfer and capture on a metal oxide surface.

    PubMed

    Brennan, Bradley J; Durrell, Alec C; Koepf, Matthieu; Crabtree, Robert H; Brudvig, Gary W

    2015-05-21

    Current molecular water-oxidation photoelectrocatalytic cells have substantial kinetic limitations under normal solar photon flux where electron-hole recombination processes may outcompete charge buildup on the catalytic centers. One method of overcoming these limitations is to design a system where multiple light-harvesting dyes work cooperatively with a single catalyst. We report a porphyrin monomer/dyad array for analysis of lateral hole transfer on a SnO2 surface consisting of a free-base porphyrin that functions to absorb light and initiate charge injection into the conduction band of SnO2, which leaves a positive charge on the organic moiety, and a free-base porphyrin/Zn-porphyrin dyad molecule that functions as a thermodynamic trap for the photoinduced holes. By using transient absorption spectroscopy, we have determined that the holes on the surface-bound free-base porphyrins are highly mobile via electron self-exchange between close-packed neighbors. The lateral charge-transfer processes were modelled by treating the system statistically with a random-walk method that utilizes experimentally derived kinetic parameters. The results of the modelling indicate that each self-exchange (hop) occurs within 25 ns and that the holes are efficiently transferred to the Zn-porphyrin. This hole-harvesting scheme provides a framework for enhancing the efficiency of multielectron photoelectrocatalytic reactions such as the four-electron oxidation of water.

  4. Membrane/mediator-free rechargeable enzymatic biofuel cell utilizing graphene/single-wall carbon nanotube cogel electrodes.

    PubMed

    Campbell, Alan S; Jeong, Yeon Joo; Geier, Steven M; Koepsel, Richard R; Russell, Alan J; Islam, Mohammad F

    2015-02-25

    Enzymatic biofuel cells (EBFCs) utilize enzymes to convert chemical energy present in renewable biofuels into electrical energy and have shown much promise in the continuous powering of implantable devices. Currently, however, EBFCs are greatly limited in terms of power and operational stability with a majority of reported improvements requiring the inclusion of potentially toxic and unstable electron transfer mediators or multicompartment systems separated by a semipermeable membrane resulting in complicated setups. We report on the development of a simple, membrane/mediator-free EBFC utilizing novel electrodes of graphene and single-wall carbon nanotube cogel. These cogel electrodes had large surface area (∼ 800 m(2) g(-1)) that enabled high enzyme loading, large porosity for unhindered glucose transport and moderate electrical conductivity (∼ 0.2 S cm(-1)) for efficient charge collection. Glucose oxidase and bilirubin oxidase were physically adsorbed onto these electrodes to form anodes and cathodes, respectively, and the EBFC produced power densities up to 0.19 mW cm(-2) that correlated to 0.65 mW mL(-1) or 140 mW g(-1) of GOX with an open circuit voltage of 0.61 V. Further, the electrodes were rejuvenated by a simple wash and reloading procedure. We postulate these porous and ultrahigh surface area electrodes will be useful for biosensing applications, and will allow reuse of EBFCs.

  5. Utilizing Combined Methodologies to Define the Role of Plasma Membrane Delivery During Axon Branching and Neuronal Morphogenesis.

    PubMed

    Winkle, Cortney C; Hanlin, Christopher C; Gupton, Stephanie L

    2016-03-16

    During neural development, growing axons extend to multiple synaptic partners by elaborating axonal branches. Axon branching is promoted by extracellular guidance cues like netrin-1 and results in dramatic increases to the surface area of the axonal plasma membrane. Netrin-1-dependent axon branching likely involves temporal and spatial control of plasma membrane expansion, the components of which are supplied through exocytic vesicle fusion. These fusion events are preceded by formation of SNARE complexes, comprising a v-SNARE, such as VAMP2 (vesicle-associated membrane protein 2), and plasma membrane t-SNAREs, syntaxin-1 and SNAP25 (synaptosomal-associated protein 25). Detailed herein isa multi-pronged approach used to examine the role of SNARE mediated exocytosis in axon branching. The strength of the combined approach is data acquisition at a range of spatial and temporal resolutions, spanning from the dynamics of single vesicle fusion events in individual neurons to SNARE complex formation and axon branching in populations of cultured neurons. This protocol takes advantage of established biochemical approaches to assay levels of endogenous SNARE complexes and Total Internal Reflection Fluorescence (TIRF) microscopy of cortical neurons expressing VAMP2 tagged with a pH-sensitive GFP (VAMP2-pHlourin) to identify netrin-1 dependent changes in exocytic activity in individual neurons. To elucidate the timing of netrin-1-dependent branching, time-lapse differential interference contrast (DIC) microscopy of single neurons over the order of hours is utilized. Fixed cell immunofluorescence paired with botulinum neurotoxins that cleave SNARE machinery and block exocytosis demonstrates that netrin-1 dependent axon branching requires SNARE-mediated exocytic activity.

  6. Utilizing Combined Methodologies to Define the Role of Plasma Membrane Delivery During Axon Branching and Neuronal Morphogenesis

    PubMed Central

    Winkle, Cortney C.; Hanlin, Christopher C.; Gupton, Stephanie L.

    2016-01-01

    During neural development, growing axons extend to multiple synaptic partners by elaborating axonal branches. Axon branching is promoted by extracellular guidance cues like netrin-1 and results in dramatic increases to the surface area of the axonal plasma membrane. Netrin-1-dependent axon branching likely involves temporal and spatial control of plasma membrane expansion, the components of which are supplied through exocytic vesicle fusion. These fusion events are preceded by formation of SNARE complexes, comprising a v-SNARE, such as VAMP2 (vesicle-associated membrane protein 2), and plasma membrane t-SNAREs, syntaxin-1 and SNAP25 (synaptosomal-associated protein 25). Detailed herein is a multi-pronged approach used to examine the role of SNARE mediated exocytosis in axon branching. The strength of the combined approach is data acquisition at a range of spatial and temporal resolutions, spanning from the dynamics of single vesicle fusion events in individual neurons to SNARE complex formation and axon branching in populations of cultured neurons. This protocol takes advantage of established biochemical approaches to assay levels of endogenous SNARE complexes and Total Internal Reflection Fluorescence (TIRF) microscopy of cortical neurons expressing VAMP2 tagged with a pH-sensitive GFP (VAMP2-pHlourin) to identify netrin-1 dependent changes in exocytic activity in individual neurons. To elucidate the timing of netrin-1-dependent branching, time-lapse differential interference contrast (DIC) microscopy of single neurons over the order of hours is utilized. Fixed cell immunofluorescence paired with botulinum neurotoxins that cleave SNARE machinery and block exocytosis demonstrates that netrin-1 dependent axon branching requires SNARE-mediated exocytic activity. PMID:27023471

  7. Review on utilization of the pervaporation membrane for passive vapor feed direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Fauzi, N. F. I.; Hasran, U. A.; Kamarudin, S. K.

    2013-12-01

    The Direct Methanol Fuel Cell (DMFC) is a promising portable power source for mobile electronic devices because of its advantages including easy fuel storage, high energy density, low temperature operation and compact structure. In DMFC, methanol is used as a fuel source where it can be fed in liquid or vapor phase. However, the vapor feed DMFC has an advantage over the liquid feed system as it has the potential to have a higher operating temperature to increase the reaction rates and power outputs, to enhance the mass transfers, to reduce methanol crossover, reliable for high methanol concentration and it can increase the fuel cell performance. Methanol vapor can be delivered to the anode by using a pervaporation membrane, heating the liquid methanol or another method that compatible. Therefore, this paper is a review on vapor feed DMFC as a better energy source than liquid feed DMFC, the pervaporation membrane used to vaporize methanol feed from the reservoir and its applications in vapor feed DMFC.

  8. The utilization of round window membrane surface tension in facilitating slim electrodes insertion during cochlear implantation.

    PubMed

    Nada, Ihab; Abdelhamid, Ahmed Nabil; Negm, Ahmed

    2017-06-24

    This is a prospective randomized study aimed to evaluate the round window membrane (RWM) surface tension in facilitating slim electrodes insertion during cochlear implantation. A total number of (118) children were included in this study (118 implantations). Mean age was 36.72 months (range from 18 to 60 months). This study was conducted from January 2015 to September 2016 at a cochlear implant centre in a tertiary referral hospital. Slit incision in the anterosuperior quadrant of the RWM was done in 70 cases, While RWM cruciate incision was done in 48 cases. Of the 48 patients who underwent RWM cruciate incision, 13 cases had no problem, while in 35 cases, we faced difficult insertion. When slit incision of the RWM was done (70 cases), 68 cases showed smooth insertion, meanwhile, we faced increased operative time due to flopping of the electrode in 2 cases only. Moreover, residual low-frequency hearing preservation was more achieved when slit incision of the RWM was done. Tensile strength of the round window membrane after slit incision of the RWM offers support to slim electrodes during introduction, decreasing incidence of kinking and floppiness, hence shortening the maneuver time and minimizing the number of trials. This facilitates easy smooth slim electrodes introduction, decreasing intracochlear trauma. Moreover, slit incision of the RWM may offer better residual hearing preservations than cruciate incision of the RWM during slim electrodes introduction.

  9. Organization and dynamics of membrane probes and proteins utilizing the red edge excitation shift.

    PubMed

    Haldar, Sourav; Chaudhuri, Arunima; Chattopadhyay, Amitabha

    2011-05-19

    Dynamics of confined water has interesting implications in the organization and function of molecular assemblies such as membranes. A direct consequence of this type of organization is the restriction imposed on the mobility of the constituent structural units. Interestingly, this restriction (confinement) of mobility couples the motion of solvent (water) molecules with the slow moving molecules in the assembly. It is in this context that the red edge excitation shift (REES) represents a sensitive approach to monitor the environment and dynamics around a fluorophore in such organized assemblies. A shift in the wavelength of maximum fluorescence emission toward higher wavelengths, caused by a shift in the excitation wavelength toward the red edge of the absorption band, is termed REES. REES relies on slow solvent reorientation in the excited state of a fluorophore that can be used to monitor the environment and dynamics around a fluorophore in a host assembly. In this article, we focus on the application of REES to monitor organization and dynamics of membrane probes and proteins. © 2011 American Chemical Society

  10. Porphyrin content of the cysticercus of Taenia solium.

    PubMed

    Larralde, C; Zedillo, G M; Lagunoff, D; Ludowyke, R; Montoya, R M; Goodsaid, F; Dreyfus, G; Sciutto, E; Govezensky, T; Diaz, M L

    1986-08-01

    The strong red fluorescence of the cysticercus of Taenia solium depends on the presence of several porphyrins in the vesicular fluid of the parasite: probably protoporphyrin IX, coproporphyin I or III, and 2 decarboxylated porphyrins intermediate between uroporphyrin and coproporphyrin. Cyst porphyrins associated to form conglomerates of high molecular weight that dissociated in acid solutions and were not antigenic themselves nor associated with antigenic molecules. An appreciable fraction of the porphyrins was capable of undergoing oxidation and reduction, indicating that some of the porphyrins were complexed with metal ions. The metabolic basis for the accumulation of porphyrins is unknown. Preliminary results suggest that conditions deleterious to the cysticercus cause release of porphyrins so that the appearance of porphyrins in the cerebrospinal fluid of neurocysticercotic patients may prove useful in monitoring therapeutic attacks on the parasite.

  11. Polymer Electrolyte Membrane Electrolyzers Utilizing Non-precious Mo-based Hydrogen Evolution Catalysts.

    PubMed

    Ng, Jia Wei Desmond; Hellstern, Thomas R; Kibsgaard, Jakob; Hinckley, Allison C; Benck, Jesse D; Jaramillo, Thomas F

    2015-10-26

    The development of low-cost hydrogen evolution reaction (HER) catalysts that can be readily integrated into electrolyzers is critical if H2 from renewable electricity-powered electrolysis is to compete cost effectively with steam reforming. Herein, we report three distinct earth-abundant Mo-based catalysts, namely those based on MoSx , [Mo3 S13 ](2-) nanoclusters, and sulfur-doped Mo phosphide (MoP|S), loaded onto carbon supports. The catalysts were synthesized through facile impregnation-sulfidization routes specifically designed for catalyst-device compatibility. Fundamental electrochemical studies demonstrate the excellent HER activity and stability of the Mo-sulfide based catalysts in an acidic environment, and the resulting polymer electrolyte membrane (PEM) electrolyzers that integrate these catalysts exhibit high efficiency and durability. This work is an important step towards the goal of replacing Pt with earth-abundant catalysts for the HER in commercial PEM electrolyzers.

  12. Expanded resources through utilization of a primary care giver extracorporeal membrane oxygenation model.

    PubMed

    Freeman, Regi; Nault, Chrissy; Mowry, Jole'; Baldridge, Paula

    2012-01-01

    Extracorporeal membrane oxygenation (ECMO) is a long-term extracorporeal support for critically ill patients with life-threatening compromises in cardiac and/or respiratory function. The unpredictability of ECMO resources for a large pediatric and adult population prompted a need for the ability to respond to significant fluctuations in the volume of patients on ECMO. Through multidisciplinary collaboration, the Primary Care Giver (PCG) ECMO Staffing Model was developed to accommodate unpredictable fluctuations in ECMO activity and to maintain flexibility and fiscal responsibility in turbulent economic times. Advancements in extracorporeal technology supported the opportunity to develop a safe and extended staffing model for ECMO. Combining the use of a centrifugal pump system with specialized and experienced cardiovascular intensive care nurses and the ECMO specialist team provided a milieu for education and training to support the new staffing model. The PCG ECMO model provides a safe, flexible, and fiscally responsible staffing model for variable ECMO activity.

  13. Pluronic F127 as a cell encapsulation material: utilization of membrane-stabilizing agents.

    PubMed

    Khattak, Sarwat F; Bhatia, Surita R; Roberts, Susan C

    2005-01-01

    Thermoreversible gelation of the copolymer Pluronic F127 (generic name, poloxamer 407) in water makes it a unique candidate for cell encapsulation applications, either alone or to promote cell seeding and attachment in tissue scaffolds. At concentrations of 15-20% (w/w), aqueous Pluronic F127 (F127) solutions gel at physiological temperatures. The effect of F127 on viability and proliferation of human liver carcinoma cells (HepG2) was determined for both liquid and gel formulations. Cell concentration and viability over a 5-day period were measured by the trypan blue assay via hemocytometry and results were confirmed in both the MTT and LDH assays. With 0.1-5% (w/w) F127 (liquid), cells proliferated and maintained high viability over 5 days. However, at 10% (w/w) F127 (liquid), there was a significant decrease in cell viability and no cell proliferation was evident. HepG2 cell encapsulation in F127 concentrations ranging from 15 to 20% (w/w) (gel) resulted in complete cell death by 5 days. This was also true for the HMEC-1 (endothelial) and L6 (muscle) cell lines evaluated. Cell-seeding density did not affect cell survival or proliferation. Membrane-stabilizing agents (hydrocortisone, glucose, and glycerol) were added to the F127 gel formulations to improve cell viability. The steroid hydrocortisone demonstrated the most significant improvement in viability, from <2% (in F127 alone) to >70% (with 60 nM hydrocortisone added). These results suggest that F127 formulations supplemented with membrane-stabilizing agents can serve as viable cell encapsulation materials. In addition, hydrocortisone may be generally useful in the promotion of cell viability for a wide range of encapsulation materials.

  14. The severity of hereditary porphyria is modulated by the porphyrin exporter and Lan antigen ABCB6

    PubMed Central

    Fukuda, Yu; Cheong, Pak Leng; Lynch, John; Brighton, Cheryl; Frase, Sharon; Kargas, Vasileios; Rampersaud, Evadnie; Wang, Yao; Sankaran, Vijay G.; Yu, Bing; Ney, Paul A.; Weiss, Mitchell J.; Vogel, Peter; Bond, Peter J.; Ford, Robert C.; Trent, Ronald J.; Schuetz, John D.

    2016-01-01

    Hereditary porphyrias are caused by mutations in genes that encode haem biosynthetic enzymes with resultant buildup of cytotoxic metabolic porphyrin intermediates. A long-standing open question is why the same causal porphyria mutations exhibit widely variable penetrance and expressivity in different individuals. Here we show that severely affected porphyria patients harbour variant alleles in the ABCB6 gene, also known as Lan, which encodes an ATP-binding cassette (ABC) transporter. Plasma membrane ABCB6 exports a variety of disease-related porphyrins. Functional studies show that most of these ABCB6 variants are expressed poorly and/or have impaired function. Accordingly, homozygous disruption of the Abcb6 gene in mice exacerbates porphyria phenotypes in the Fechm1Pas mouse model, as evidenced by increased porphyrin accumulation, and marked liver injury. Collectively, these studies support ABCB6 role as a genetic modifier of porphyria and suggest that porphyrin-inducing drugs may produce excessive toxicities in individuals with the rare Lan(−) blood type. PMID:27507172

  15. Porphyrin Nanodroplets: Sub-micrometer Ultrasound and Photoacoustic Contrast Imaging Agents.

    PubMed

    Paproski, Robert J; Forbrich, Alexander; Huynh, Elizabeth; Chen, Juan; Lewis, John D; Zheng, Gang; Zemp, Roger J

    2016-01-20

    A novel class of all-organic nanoscale porphyrin nanodroplet agents is presented which is suitable for multimodality ultrasound and photoacoustic molecular imaging. Previous multimodality photoacoustic-ultrasound agents are either not organic, or not yet demonstrated to exhibit enhanced accumulation in leaky tumor vasculature, perhaps because of large diameters. In the current study, porphyrin nanodroplets are created with a mean diameter of 185 nm which is small enough to exhibit the enhanced permeability and retention effect. Porphyrin within the nanodroplet shell has strong optical absorption at 705 nm with an estimated molar extinction coefficient >5 × 10(9) m(-1) cm(-1) , allowing both ultrasound and photoacoustic contrast in the same nanoparticle using all organic materials. The potential of nanodroplets is that they may be phase-changed into microbubbles using high pressure ultrasound, providing ultrasound contrast with single-bubble sensitivity. Multispectral photoacoustic imaging allows visualization of nanodroplets when injected intratumorally in an HT1080 tumor in the chorioallantoic membrane of a chicken embryo. Intravital microscopy imaging of Hep3-GFP and HT1080-GFP tumors in chicken embryos determines that nanodroplets accumulated throughout or at the periphery of tumors, suggesting that porphyrin nanodroplets may be useful for enhancing the visualization of tumors with ultrasound and/or photoacoustic imaging.

  16. The severity of hereditary porphyria is modulated by the porphyrin exporter and Lan antigen ABCB6.

    PubMed

    Fukuda, Yu; Cheong, Pak Leng; Lynch, John; Brighton, Cheryl; Frase, Sharon; Kargas, Vasileios; Rampersaud, Evadnie; Wang, Yao; Sankaran, Vijay G; Yu, Bing; Ney, Paul A; Weiss, Mitchell J; Vogel, Peter; Bond, Peter J; Ford, Robert C; Trent, Ronald J; Schuetz, John D

    2016-08-10

    Hereditary porphyrias are caused by mutations in genes that encode haem biosynthetic enzymes with resultant buildup of cytotoxic metabolic porphyrin intermediates. A long-standing open question is why the same causal porphyria mutations exhibit widely variable penetrance and expressivity in different individuals. Here we show that severely affected porphyria patients harbour variant alleles in the ABCB6 gene, also known as Lan, which encodes an ATP-binding cassette (ABC) transporter. Plasma membrane ABCB6 exports a variety of disease-related porphyrins. Functional studies show that most of these ABCB6 variants are expressed poorly and/or have impaired function. Accordingly, homozygous disruption of the Abcb6 gene in mice exacerbates porphyria phenotypes in the Fech(m1Pas) mouse model, as evidenced by increased porphyrin accumulation, and marked liver injury. Collectively, these studies support ABCB6 role as a genetic modifier of porphyria and suggest that porphyrin-inducing drugs may produce excessive toxicities in individuals with the rare Lan(-) blood type.

  17. Photodynamic action of porphyrin on Ca2+ influx in endoplasmic reticulum: a comparison with mitochondria.

    PubMed Central

    Ricchelli, F; Barbato, P; Milani, M; Gobbo, S; Salet, C; Moreno, G

    1999-01-01

    We have studied the distribution properties of haematoporphyrin (HP) and protoporphyrin (PP) in mitochondria and endoplasmic reticulum after isolation from rat liver. The photosensitizing efficiency of porphyrin on the Ca2+ influx function of microsomes has been compared with that obtained on Ca2+ uptake in mitochondria. HP and PP are accumulated in microsomes to a greater extent than in mitochondria, both porphyrins binding to membrane protein sites. The Ca2+ influx functions of mitochondria and microsomes, before and after irradiation in the presence of HP or PP, were studied by following the changes in the free Ca2+ concentration in the medium as revealed by the variations in fluorescence intensity of the Ca2+ indicator Calcium Green-1. For the same amount of incorporated porphyrin, the Ca2+ influx function of microsomes is degraded by irradiation more rapidly than that of mitochondria. The protective effect of dithiothreitol suggests that thiol groups in the Ca2+-transporting enzyme are the preferential targets of the photodynamic effect. These results suggest that intracellular Ca2+ movements are altered primarily by the endoplasmic reticulum rather than by mitochondrial damage, in good agreement with other observations made in porphyrin-loaded irradiated cells. PMID:9931319

  18. Metal complexes of substituted Gable porphyrins as oxidation catalysts

    DOEpatents

    Lyons, J.E.; Ellis, P.E. Jr.; Wagner, R.W.

    1996-01-02

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

  19. Metal complexes of substituted Gable porphyrins as oxidation catalysts

    DOEpatents

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

    1996-01-01

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

  20. Interactions of porphyrins and transfer RNA.

    PubMed

    Foster, N; Singhal, A K; Smith, M W; Marcos, N G; Schray, K J

    1988-07-13

    The interactions of the free base porphyrin, tetra-(4N-methylpyridyl)porphyrin and its copper(II), manganese(III) and zinc(II) complexes with brewer's yeast type V phenylalaninyl tRNA were evaluated by UV-visible spectroscopy, circular dichroism and melting temperature studies over a range of magnesium ion concentrations and ionic strengths. Scatchard analysis of absorption spectra of the porphyrins in the presence of tRNA showed the free base, copper and zinc porphyrins to have binding constants of 7.3 X 10(7), 1.7 X 10(6) and 2.3 X 10(8), respectively; the manganese(III) complex did not demonstrate changes in its electronic spectra that enable the calculation of a binding constant. The results of the spectroscopic studies indicate a mode of binding for the free base, copper(II) and zinc(II) complexes that is neither intercalative nor simply outside electrostatic. The magnitude of the binding constants and the UV-visible results support intercalation, but the analyses of the thermal denaturation studies and the circular dichroism evaluations suggest that the porphyrins are associating at a single site in a fold of the tertiary structure of the tRNA close to several crucial hydrogen bonds, perhaps in the vicinity of the P10 loop. That the manganese(III) complex does not bind in this site points to constraints on the axial thickness of a molecule that may be accommodated in this locus.

  1. Tuning the Electronic Structure and Properties of Perylene-Porphyrin-Perylene Panchromatic Absorbers.

    PubMed

    Amanpour, Javad; Hu, Gongfang; Alexy, Eric J; Mandal, Amit Kumar; Kang, Hyun Suk; Yuen, Jonathan M; Diers, James R; Bocian, David F; Lindsey, Jonathan S; Holten, Dewey

    2016-09-29

    -linked porphyrin-perylene architectures that can help guide next-generation designs and utilization of these systems.

  2. Integrated Microfluidic Membrane Transistor Utilizing Chemical Information for On-Chip Flow Control

    PubMed Central

    Frank, Philipp; Schreiter, Joerg; Haefner, Sebastian; Paschew, Georgi; Voigt, Andreas; Richter, Andreas

    2016-01-01

    Microfluidics is a great enabling technology for biology, biotechnology, chemistry and general life sciences. Despite many promising predictions of its progress, microfluidics has not reached its full potential yet. To unleash this potential, we propose the use of intrinsically active hydrogels, which work as sensors and actuators at the same time, in microfluidic channel networks. These materials transfer a chemical input signal such as a substance concentration into a mechanical output. This way chemical information is processed and analyzed on the spot without the need for an external control unit. Inspired by the development electronics, our approach focuses on the development of single transistor-like components, which have the potential to be used in an integrated circuit technology. Here, we present membrane isolated chemical volume phase transition transistor (MIS-CVPT). The device is characterized in terms of the flow rate from source to drain, depending on the chemical concentration in the control channel, the source-drain pressure drop and the operating temperature. PMID:27571209

  3. Utilization of concentrate after membrane filtration of sugar beet thin juice for ethanol production.

    PubMed

    Kawa-Rygielska, Joanna; Pietrzak, Witold; Regiec, Piotr; Stencel, Piotr

    2013-04-01

    The subject of this study was to investigate the feasibility of the concentrate obtained after membrane ultrafiltration of sugar beet thin juice for ethanol production and selection of fermentation conditions (yeast strain and media supplementation). Resulting concentrate was subjected to batch ethanol fermentation using two strains of Saccharomyces cerevisiae (Ethanol Red and Safdistill C-70). The effect of different forms of media supplementation (mineral salts: (NH4)2SO4, K2HPO4, MgCl2; urea+Mg3(PO4)2 and yeast extract) on the fermentation course was also studied. It was stated that sugar beet juice concentrate is suitable for ethanol production yielding, depending on the yeast strain, ca. 85-87 g L(-1) ethanol with ca. 82% practical yield and more than 95% of sugars consumption after 72 h of fermentation. Nutrients enrichment further increased ethanol yield. The best results were obtained for media supplemented with urea+Mg3(PO4)2 yielding 91.16-92.06 g L(-1) ethanol with practical yield ranging 84.78-85.62% and full sugars consumption. Copyright © 2013. Published by Elsevier Ltd.

  4. Utilizing biomarker techniques: Cellular membrane potential as a biomarker of subchronic toxicity

    SciTech Connect

    Fort, D.J.; Stover, E.L.; Burks, S.L.; Atherton, R.A.; Blankmeyer, J.T.

    1996-12-31

    A biomarker assay designed to monitor the health of Daphnia sp. as well as evaluate sites of toxicant action was used to study the toxic effects of copper, diazinon, and polyacrylamide. The assay used the uptake of a fluorescent cellular membrane-bound dye and corresponding fluorescence measurement as an early potential is an indicator of potential cellular stress. Following short-term exposure to the electrochromic dye, di-4-ANEPPS, and the toxicants, fluorescence readings were collected, stored in a database management system, and output for graphical display and statistical analysis. Median inhibitory concentrations (IC50), No Observed Effect Concentrations (NOEC), and Lowest Observed Effect Concentrations (LOEC) values for copper were approximately 52.6, 35.0, and 50.0 {micro}g/L. The approximate IC50, NOEC, LOEC values for diazinon and polyacrylamide were 0.45, 0.25, and 0.50 {micro}g/L; and 350.0, 300.0, and 500.0 {micro}g/L, respectively. Fluorescence microscopy indicated that copper primarily affected the mouth parts (orofacial) and digestive tract. Diazinon, however, primarily caused an effect on the anterior portion of the nervous system. Polyacrylamide appeared to induce toxicity throughout the entire epithelial layer of the Daphnia. These results suggested this assay may be effectively used to monitor for organism stress or toxicity as well as evaluate potential sites of toxic action.

  5. Integrated Microfluidic Membrane Transistor Utilizing Chemical Information for On-Chip Flow Control.

    PubMed

    Frank, Philipp; Schreiter, Joerg; Haefner, Sebastian; Paschew, Georgi; Voigt, Andreas; Richter, Andreas

    2016-01-01

    Microfluidics is a great enabling technology for biology, biotechnology, chemistry and general life sciences. Despite many promising predictions of its progress, microfluidics has not reached its full potential yet. To unleash this potential, we propose the use of intrinsically active hydrogels, which work as sensors and actuators at the same time, in microfluidic channel networks. These materials transfer a chemical input signal such as a substance concentration into a mechanical output. This way chemical information is processed and analyzed on the spot without the need for an external control unit. Inspired by the development electronics, our approach focuses on the development of single transistor-like components, which have the potential to be used in an integrated circuit technology. Here, we present membrane isolated chemical volume phase transition transistor (MIS-CVPT). The device is characterized in terms of the flow rate from source to drain, depending on the chemical concentration in the control channel, the source-drain pressure drop and the operating temperature.

  6. LDRD final report on imaging self-organization of proteins in membranes by photocatalytic nano-tagging.

    SciTech Connect

    Zavadil, Kevin Robert; Shelnutt, John Allen; Sasaki, Darryl Yoshio; Song, Yujiang; Medforth, Craig J.

    2005-11-01

    We have developed a new nanotagging technology for detecting and imaging the self-organization of proteins and other components of membranes at nanometer resolution for the purpose of investigating cell signaling and other membrane-mediated biological processes. We used protein-, lipid-, or drug-bound porphyrin photocatalysts to grow in-situ nanometer-sized metal particles, which reveal the location of the porphyrin-labeled molecules by electron microscopy. We initially used photocatalytic nanotagging to image assembled multi-component proteins and to monitor the distribution of lipids and porphyrin labels in liposomes. For example, by exchanging the heme molecules in hemoproteins with a photocatalytic tin porphyrin, a nanoparticle was grown at each heme site of the protein. The result obtained from electron microscopy for a tagged multi-subunit protein such as hemoglobin is a symmetric constellation of a specific number of nanoparticle tags, four in the case of the hemoglobin tetramer. Methods for covalently linking photocatalytic porphyrin labels to lipids and proteins were also developed to detect and image the self-organization of lipids, protein-protein supercomplexes, and membrane-protein complexes. Procedures for making photocatalytic porphyrin-drug, porphyrin-lipid, and porphyrin-protein hybrids for non-porphyrin-binding proteins and membrane components were pursued and the first porphyrin-labeled lipids was investigated in liposomal membrane models. Our photocatalytic nanotagging technique may ultimately allow membrane self-organization and cell signaling processes to be imaged in living cells. Fluorescence and plasmonic spectra of the tagged proteins might also provide additional information about protein association and membrane organization. In addition, a porphyrin-aspirin or other NSAID hybrid may be used to grow metal nanotags for the pharmacologically important COX enzymes in membranes so that the distribution of the protein can be imaged at the

  7. Performance of vapor-fed direct dimethyl ether fuel cell utilizing high temperature polybenzimidazole polymer electrolyte membrane

    NASA Astrophysics Data System (ADS)

    Neutzler, Jay; Qian, Guoqing; Huang, Kevin; Benicewicz, Brian

    2012-10-01

    There is increasing interest in dimethyl ether (DME) as a synthetic fuel. It has present-day relevance and introduces an effective path forward as an energy-dense, low-pressure hydrogen carrier/storage fuel for fuel cells with applications in transportation, stationary, and portable power. Direct reaction DME fuel cells have particular relevance to portable power. This study presents the performance of the vapor-fed direct reaction of DME using high temperature Polybenzimidazole (PBI) Polymer Electrolyte Membrane (PEM). Catalyzed PBI membrane utilized a Pt/Ru black anode and a Pt/C supported cathode. Performance was evaluated from temperatures of 180 °C-210 °C and at pressures from 100 kPa to 300 kPa. A strong performance correlation was observed in this study for these temperatures and pressures. A peak power density of 50 mW cm-2 was achieved at 180 °C without back pressure, whereas, an increase to 129 mW cm-2 was achieved at 210 °C at 300 kPa pressure. The performance of high temperature PBI PEMFCs with direct vapor-fed DME are investigated with emphasis on the critical variables of cell operation; temperature, back pressure, and humidity.

  8. Triiodothyronine Facilitates Weaning From Extracorporeal Membrane Oxygenation by Improved Mitochondrial Substrate Utilization

    PubMed Central

    Files, Matthew D.; Kajimoto, Masaki; O'Kelly Priddy, Colleen M.; Ledee, Dolena R.; Xu, Chun; Des Rosiers, Christine; Isern, Nancy; Portman, Michael A.

    2014-01-01

    Background Extracorporeal membrane oxygenation (ECMO) provides a bridge to recovery after myocardial injury in infants and children, yet morbidity and mortality remain high. Weaning from the circuit requires adequate cardiac contractile function, which can be impaired by metabolic disturbances induced either by ischemia‐reperfusion and/or by ECMO. We tested the hypothesis that although ECMO partially ameliorates metabolic abnormalities induced by ischemia‐reperfusion, these abnormalities persist or recur with weaning. We also determined if thyroid hormone supplementation (triiodothyronine) during ECMO improves oxidative metabolism and cardiac function. Methods and Results Neonatal piglets underwent transient coronary ischemia to induce cardiac injury then were separated into 4 groups based on loading status. Piglets without coronary ischemia served as controls. We infused into the left coronary artery [2‐13C]pyruvate and [13C6, 15N]l‐leucine to evaluate oxidative metabolism by gas chromatography‐mass spectroscopy and nuclear magnetic resonance methods. ECMO improved survival, increased oxidative substrate contribution through pyruvate dehydrogenase, reduced succinate and fumarate accumulation, and ameliorated ATP depletion induced by ischemia. The functional and metabolic benefit of ECMO was lost with weaning, yet triiodothyronine supplementation during ECMO restored function, increased relative pyruvate dehydrogenase flux, reduced succinate and fumarate, and preserved ATP stores. Conclusions Although ECMO provides metabolic rest by decreasing energy demand, metabolic impairments persist, and are exacerbated with weaning. Treating ECMO‐induced thyroid depression with triiodothyronine improves substrate flux, myocardial oxidative capacity and cardiac contractile function. This translational model suggests that metabolic targeting can improve weaning. PMID:24650924

  9. Blood porphyrin luminescence and tumor growth correlation

    NASA Astrophysics Data System (ADS)

    Courrol, Lilia Coronato; Silva, Flávia Rodrigues de Oliveira; Bellini, Maria Helena; Mansano, Ronaldo Domingues; Schor, Nestor; Vieira, Nilson Dias, Jr.

    2007-02-01

    Fluorescence technique appears very important for the diagnosis of cancer. Fluorescence detection has advantages over other light-based investigation methods: high sensitivity, high speed, and safety. Renal cell carcinoma (RCC) accounts for approximately 3% of new cancer incidence and mortality in the United States. Unfortunately many RCC masses remain asymptomatic and nonpalpable until they are advanced. Diagnosis and localization of early carcinoma play an important role in the prevention and curative treatment of RCC. Certain drugs or chemicals such as porphyrin derivatives accumulate substantially more in tumors than normal tissues. The autofluorescence of blood porphyrin of healthy and tumor induced male SCID mice was analyzed using fluorescence and excitation spectroscopy. A significant contrast between normal and tumor blood could be established. Blood porphyrin fluorophore showed enhanced fluorescence band (around 630 nm) in function of the tumor growth. This indicates that either the autofluorescence intensity of the blood fluorescence may provide a good parameter for the "first approximation" characterization of the tumor stage.

  10. High efficiency porphyrin sensitized mesoscopic solar cells

    NASA Astrophysics Data System (ADS)

    Giordano, Fabrizio; Yi, Chenyi; Teuscher, Joël.; Zakeeruddin, Shaik M.; Grätzel, Michael

    2014-10-01

    Dye-Sensitized Solar Cells (DSSC) represents a reliable technology, ready for the market and able to compete with silicon solar cells for specific fields of application. Porphyrin dyes allow reaching high power conversion efficiency in conjunction with cobalt redox electrolytes due to larger open circuit potentials. The bigger size of the cobalt complexes compared to standard iodide/triiodide redox couple hampers its percolation through the meso-porous TiO2 network, thus impairing the regeneration process. In case of porphyrin dyes mass transport problems in the electrolyte need to be carefully handled, due to the large size of the sensitizing molecule and the bulky cobalt complexes. Herein we report the study of structural variations on porphyrin sensitizers and their influence on the DSSC performance with cobalt based redox electrolyte.

  11. Resonance Raman spectroscopy study of protonated porphyrin

    NASA Astrophysics Data System (ADS)

    Gorski, A.; Starukhin, A.; Stavrov, S.; Gawinkowski, S.; Waluk, J.

    2017-02-01

    Resonance Raman microscopy was used to study the resonance Raman scattering of the diacid (diprotonated form) of free-base porphyrin (21H,23H-porphine) in a crystal powder and KBr pellets. Intensive lines in the spectral range between 100 ÷ 1000 cm- 1 have been detected and assigned as spectral manifestation of out-of-plane modes. The Raman spectra were simulated by means of DFT methods and compared with the experimental data. It is evident from experimental and theoretical results that the activation of out-of-plane modes arises from saddle distortion of the porphyrin macrocycle upon formation of its diprotonated form.

  12. Effect of high loading on substrate utilization kinetics and microbial community structure in super fast submerged membrane bioreactor.

    PubMed

    Sözen, S; Çokgör, E U; Başaran, S Teksoy; Aysel, M; Akarsubaşı, A; Ergal, I; Kurt, H; Pala-Ozkok, I; Orhon, D

    2014-05-01

    The study investigated the effect of high substrate loading on substrate utilization kinetics, and changes inflicted on the composition of the microbial community in a superfast submerged membrane bioreactor. Submerged MBR was sequentially fed with a substrate mixture and acetate; its performance was monitored at steady-state, at extremely low sludge age values of 2.0, 1.0 and 0.5d, all adjusted to a single hydraulic retention time of 8.0 h. Each MBR run was repeated when substrate feeding was increased from 200 mg COD/L to 1000 mg COD/L. Substrate utilization kinetics was altered to significantly lower levels when the MBR was adjusted to higher substrate loadings. Molecular analysis of the biomass revealed that variable process kinetics could be correlated with parallel changes in the composition of the microbial community, mainly by a replacement mechanism, where newer species, better adapted to the new growth conditions, substituted others that are washed out from the system. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. An Outer Membrane Protein Involved in the Uptake of Glucose Is Essential for Cytophaga hutchinsonii Cellulose Utilization

    PubMed Central

    Zhou, Hong; Wang, Xia; Yang, Tengteng; Zhang, Weixin; Chen, Guanjun

    2016-01-01

    Cytophaga hutchinsonii specializes in cellulose digestion by employing a collection of novel cell-associated proteins. Here, we identified a novel gene locus, CHU_1276, that is essential for C. hutchinsonii cellulose utilization. Disruption of CHU_1276 in C. hutchinsonii resulted in complete deficiency in cellulose degradation, as well as compromised assimilation of cellobiose or glucose at a low concentration. Further analysis showed that CHU_1276 was an outer membrane protein that could be induced by cellulose and low concentrations of glucose. Transcriptional profiling revealed that CHU_1276 exerted a profound effect on the genome-wide response to both glucose and Avicel and that the mutant lacking CHU_1276 displayed expression profiles very different from those of the wild-type strain under different culture conditions. Specifically, comparison of their transcriptional responses to cellulose led to the identification of a gene set potentially regulated by CHU_1276. These results suggest that CHU_1276 plays an essential role in cellulose utilization, probably by coordinating the extracellular hydrolysis of cellulose substrate with the intracellular uptake of the hydrolysis product in C. hutchinsonii. PMID:26773084

  14. Three Short Stories about Hexaarylbenzene-Porphyrin Scaffolds.

    PubMed

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

    2016-11-14

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

  15. Spectroscopic investigation on porphyrins nano-assemblies onto gold nanorods

    NASA Astrophysics Data System (ADS)

    Trapani, Mariachiara; De Luca, Giovanna; Romeo, Andrea; Castriciano, Maria Angela; Scolaro, Luigi Monsù

    2017-02-01

    The interaction between gold nanorods (Au NRs), synthesized by a conventional seeded growth protocol, and the anionic tetrakis-(4-sulfonatophenyl)porphyrin (TPPS4) has been investigated through various spectroscopic techniques. At neutral pH, the formation of H-aggregates and the inclusion of porphyrin monomers in CTAB micelles covering the nanorods have been evidenced. Under mild acidic conditions (pH = 3) a nano-hybrid assembly of porphyrin J-aggregates and Au NRs has been revealed. For the sake of comparison, Cu(II) and Zn(II) metal porphyrin derivatives as well as a cationic porphyrin have been studied in the same experimental conditions, showing that: i) CuTPPS4 forms porphyrin H-dimers onto the Au NRs; ii) ZnTPPS4 undergoes to demetallation, followed by acidification of the central core and eventually aggregation onto Au NRs; iii) cationic porphyrin does not interact with Au NRs.

  16. Surface morphology and optical properties of porphyrin/Au and Au/porphyrin/Au systems

    PubMed Central

    2013-01-01

    Porphyrin/Au and Au/porphyrin/Au systems were prepared by vacuum evaporation and vacuum sputtering onto glass substrate. The surface morphology of as-prepared systems and those subjected to annealing at 160°C was studied by optical microscopy, atomic force microscopy, and scanning electron microscopy techniques. Absorption and luminescence spectra of as-prepared and annealed samples were measured. Annealing leads to disintegration of the initially continuous gold layer and formation of gold nanoclusters. An amplification of Soret band magnitude was observed on the Au/meso-tetraphenyl porphyrin (TPP) system in comparison with mere TPP. Additional enhancement of luminescence was observed after the sample annealing. In the case of sandwich Au/porphyrin/Au structure, suppression of one of the two porphyrins’ luminescence maxima and sufficient enhancement of the second one were observed. PMID:24373347

  17. Local conformations and excited state dynamics of porphyrins and nucleic acids by 2-dimensional fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Widom, Julia R.

    Biological systems present many challenges to researchers attempting to study them using spectroscopy. Low specificity, low sensitivity, and broad and overlapping lineshapes limit the amount of information that can be obtained in experiments. Two-dimensional fluorescence spectroscopy (2D FS) is a highly sensitive and information-rich spectroscopic technique that was developed to study the conformations and excited state dynamics of systems exhibiting exciton coupling. In this dissertation, I describe a variety of extensions of 2D FS that further increase its utility for the study of biological systems. I describe experiments on a dimer of zinc tetraphenylporphyrin embedded in a membrane, in which the signals from two conformational subpopulations were separated in order to study the thermodynamics of their interconversion. I present proof-of-principle experiments on nucleic acids that utilize fluorescence resonance energy transfer to separate signals from different subpopulations. I also describe experiments in which 2D FS was performed using ultraviolet excitation to determine the conformation of a dinucleotide of a fluorescent analogue of the nucleic acid base adenine. I discuss experiments on porphyrin dimers in which 2D FS was used as a probe of excited state dynamics. Finally, I present model calculations for a proposed variation of 2D FS in which entangled photons would be used as the excitation source. These calculations suggest that this approach has the potential to yield significantly narrower spectral lineshapes than conventional 2D FS. These experiments and calculations yield new insight into the systems investigated and establish a `toolbox' of variations of 2D FS that can be used to gain as much information as possible from experiments on challenging systems such as protein-DNA complexes.

  18. Porphyrin protonation studied by magnetic circular dichroism.

    PubMed

    Štěpánek, Petr; Andrushchenko, Valery; Ruud, Kenneth; Bouř, Petr

    2012-01-12

    Magnetic circular dichroism (MCD) spectroscopy provides valuable information about electronic excited states in molecules. The interpretation of spectra is however difficult, often requiring additional theoretical calculations to rationalize the observed signal. Recent developments in time-dependent density functional theory (TDDFT) bring hope that the applicability of MCD spectroscopy for chemical problems may be significantly extended. In this study, two modern analytical TDDFT implementations are compared and used to understand experimental MCD spectra of a model porphyrin system upon protonation. Changes in porphyrin geometry and electronic structure are related to MCD intensities by comparing the spectra of 5,10,15,20-tetraphenyl-21H,23H-porphyrintetrasulfonic acid (TPPS) measured at different pH values with the TDDFT calculations. Although the theoretical results slightly depended on the chosen exchange-correlation functional, the computations provided MCD curves that could well rationalize the experimental data. The protonation of the porphyrin core causes marked changes in the MCD spectrum, whereas the role of the substituents is limited. Also, different conformations of the porphyrin substituents cause relatively minor changes of the MCD pattern, mostly in the Soret region, where the porphine and phenyl electronic transitions start to mix. The solvent environment simulated by the dielectric model caused a shift (~20 nm) of the absorption bands but only minor variations in the absorption and MCD spectral shapes. The study thus demonstrates that the recently available first-principles interpretations of MCD spectra significantly enhance the applicability of the technique for molecular structural studies.

  19. Metallic nanoshells on porphyrin-stabilized emulsions

    DOEpatents

    Wang, Haorong; Song, Yujiang; Shelnutt, John A; Medforth, Craig J

    2013-10-29

    Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.

  20. Photosensitization mechanism of Cu(ii) porphyrins.

    PubMed

    Uranga, Jon; Matxain, Jon M; Lopez, Xabier; Ugalde, Jesus M; Casanova, David

    2017-08-09

    This work presents the mechanism of the photoinduced generation of reactive oxygen species (ROS) by paramagnetic copper porphyrins in aqueous solution. Electronic structure calculations within the framework of the (time-dependent) density functional theory, (TD)DFT, reveal the details regarding the development of the atomistic and electronic structures of the copper porphyrin in solution along the set of chemical reactions accessible upon photoactivation. This study identifies the key parameters controlling the feasibility of the various reaction pathways that drive the formation of specific reactive oxygen species, ROS, i.e. superoxide, peroxyl and hydroxyl radicals. An important outcome of our results is the rationalization of how the water solvent molecules play a crucial role in most steps of the overall reaction. The present study is illustrated by focusing on one specific copper porphyrin for which precise experimental data have recently been measured, and can readily be generalized to the whole family of paramagnetic porphyrins. The conclusions of this work shed light on the rational design of metalloporphyrins as photosensitizers for photodynamic therapy.

  1. Porphyrins for boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Gabel, Detlef

    1990-01-01

    Novel compounds for treatment of brain tumors in Boron Neutron Capture Therapy are disclosed. A method for preparing the compounds as well as pharmaceutical compositions containing said compounds are also disclosed. The compounds are water soluble, non-toxic and non-labile boronated porphyrins which show significant uptake and retention in tumors.

  2. Oxygenation of Cobalt Porphyrinates: Coordination or Oxidation?

    PubMed Central

    Li, Jianfeng; Noll, Bruce C.; Oliver, Allen G.; Ferraudi, Guillermo; Lappin, A. Graham; Scheidt, W. Robert

    2010-01-01

    The X-ray characterization of the five-coordinate picket-fence porphyrin complex, [Co(TpivPP)(2-MeHim)], is reported. The complex has the displacement of cobalt from the porphyrin plane = 0.15 Å, and Co–NIm = 2.145 (3) and (Co–Np)av = 1.979(3) Å. This five-coordinate complex, in the presence of dioxygen and excess 2-methylimidazole, undergoes an unanticipated, photoinitiated atropisomerization of the porphyrin ligand, oxidation of cobalt(II) and the formation of the neutral cobalt(III) complex [Co(α,α,β,β-TpivPP)(2-MeHim)(2-MeIm−]. Two distinct examples of this complex have been structurally characterized, both have structural parameters consistent with cobalt(III). The two new Co(III) porphyrin complexes have axial Co–NIm distances ranging from 1.952 to 1.972 Å, but which allow for the distinction between imidazole and imidazolate. An interesting intermolecular hydrogen bonding network is observed that leads to infinite helical chains. UV-vis spectroscopic study suggests that [Co(TpivPP)(2-MeHIm)(O2)] is an intermediate state for the oxidation reaction and the atropisomerization process is photocatalyzed. A reaction route is proposed based on the spectroscopic studies. PMID:20104874

  3. Porphyrin-Cored Polymer Nanoparticles: Macromolecular Models for Heme Iron Coordination.

    PubMed

    Rodriguez, Kyle J; Hanlon, Ashley M; Lyon, Christopher K; Cole, Justin P; Tuten, Bryan T; Tooley, Christian A; Berda, Erik B; Pazicni, Samuel

    2016-10-03

    Porphyrin-cored polymer nanoparticles (PCPNs) were synthesized and characterized to investigate their utility as heme protein models. Created using collapsible heme-centered star polymers containing photodimerizable anthracene units, these systems afford model heme cofactors buried within hydrophobic, macromolecular environments. Spectroscopic interrogations demonstrate that PCPNs display redox and ligand-binding reactivity similar to that of native systems and thus are potential candidates for modeling biological heme iron coordination.

  4. A Ferrocene-Porphyrin Ligand for Multi-Transduction Chemical Sensor Development

    PubMed Central

    Lvova, Larisa; Galloni, Pierluca; Floris, Barbara; Lundström, Ingemar; Paolesse, Roberto; Di Natale, Corrado

    2013-01-01

    5,10,15,20-Tetraferrocenyl porphyrin, H2TFcP, a simple example of a donor-acceptor system, was tested as ligand for the development of a novel multi-transduction chemical sensors aimed at the determination of transition metal ions. The fluorescence energy transfer between ferrocene donor and porphyrin acceptor sub-units was considered. The simultaneously measured optical and potentiometric responses of solvent polymeric membranes based on H2TFcP permitted the detection of lead ions in sample solutions, in the concentration range from 2.7 × 10−7 to 3.0 × 10−3 M. The detection limit of lead determination was 0.27 μM, low enough to perform the direct analysis of Pb2+ in natural waters. PMID:23653052

  5. Porphyrin colorimetric indicators in molecular and nano-architectures.

    PubMed

    Xie, Yongshu; Hill, Jonathan P; Charvet, Richard; Ariga, Katsuhiko

    2007-09-01

    One of the most important outcomes of organic nanotechnologies could be development of well-integrated systems for sensing of particular chemical species. Use of color indicators is an attractive approach to guest reporting. Of the known chromophores, porphyrin and its derivatives are the most widely studied functional chromophores in a diverse range of research fields. In this review, recent developments in colorimetric indicator functions of porphyrin derivatives and related compounds in their molecular and nano-architectures are reviewed according to the classification: (i) rather simple porphyrin derivatives, (ii) porphyrin conjugates, (iii) porphyrins embedded in bulk materials, and (iv) porphyrins in organized films. Porphyrin derivatives with unusual structures, such as expanded and N-confused ones have been used for color indicators in specific cases. Electron and energy transfers in porphyrins conjugated with other functional moieties resulted in dynamic sensing systems including switch-on and switch-off actions. Immobilization of porphyrin color indicators in appropriate matrices is important for practical applications. Use of supramolecular films such as self-assembled monolayers, Langmuir-Blodgett films, and layer-by-layer assemblies as porphyrin nanoarchitectures often offers opportunities for colorimetric outputs based on control of their aggregate structures.

  6. Controlled intracellular generation of reactive oxygen species in human mesenchymal stem cells using porphyrin conjugated nanoparticles

    NASA Astrophysics Data System (ADS)

    Lavado, Andrea S.; Chauhan, Veeren M.; Alhaj Zen, Amer; Giuntini, Francesca; Jones, D. Rhodri E.; Boyle, Ross W.; Beeby, Andrew; Chan, Weng C.; Aylott, Jonathan W.

    2015-08-01

    Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(ii) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(ii) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn(ii) porphyrin and high numbers of irradiations of excitation light were found to generate greater amounts of ROS. A novel dye, which is transformed into fluorescent 7-hydroxy-4-trifluoromethyl-coumarin in the presence of hydrogen peroxide, provided an indirect indicator for cumulative ROS production. The mitochondrial membrane potential was monitored to investigate the destructive effect of increased intracellular ROS production. Flow cytometric analysis of nanoparticle treated hMSCs suggested irradiation with excitation light signalled controlled apoptotic cell death, rather than uncontrolled necrotic cell death. Increased intracellular ROS production did not induce phenotypic changes in hMSC subcultures.Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(ii) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(ii) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn

  7. Helicobacter pylori Salvages Purines from Extracellular Host Cell DNA Utilizing the Outer Membrane-Associated Nuclease NucT

    PubMed Central

    Liechti, George W.

    2013-01-01

    Helicobacter pylori is a bacterial pathogen that establishes life-long infections in humans, and its presence in the gastric epithelium is strongly associated with gastritis, peptic ulcer disease, and gastric cancer. Having evolved in this specific gastric niche for hundreds of thousands of years, this microbe has become dependent on its human host. Bioinformatic analysis reveals that H. pylori has lost several genes involved in the de novo synthesis of purine nucleotides, and without this pathway present, H. pylori must salvage purines from its environment in order to grow. While the presence and abundance of free purines in various mammalian tissues has been loosely quantified, the concentration of purines present within the gastric mucosa remains unknown. There is evidence, however, that a significant amount of extracellular DNA is present in the human gastric mucosal layer as a result of epithelial cell turnover, and this DNA has the potential to serve as an adequate purine source for gastric purine auxotrophs. In this study, we characterize the ability of H. pylori to grow utilizing only DNA as a purine source. We show that this ability is independent of the ComB DNA uptake system, and that H. pylori utilization of DNA as a purine source is largely influenced by the presence of an outer membrane-associated nuclease (NucT). A ΔnucT mutant exhibits significantly reduced extracellular nuclease activity and is deficient in growth when DNA is provided as the sole purine source in laboratory growth media. These growth defects are also evident when this nuclease mutant is grown in the presence of AGS cells or in purine-free tissue culture medium that has been conditioned by AGS cells in the absence of fetal bovine serum. Taken together, these results indicate that the salvage of purines from exogenous host cell DNA plays an important role in allowing H. pylori to meet its purine requirements for growth. PMID:23893109

  8. Solvent Dependence of Lateral Charge Transfer in a Porphyrin Monolayer

    DOE PAGES

    Brennan, Bradley J.; Regan, Kevin P.; Durrell, Alec C.; ...

    2016-12-19

    Lateral charge transport in a redox)active monolayer can be utilized for solar energy harvesting. We chose the porphyrin system to study the influence of the solvent on lateral hole hopping, which plays a crucial role in the charge)transfer kinetics. We also examined the influence of water, acetonitrile, and propylene carbonate as solvents. Hole)hopping lifetimes varied by nearly three orders of magnitude among solvents, ranging from 3 ns in water to 2800 ns in propylene carbonate, and increased nonlinearly as a function of added acetonitrile in aqueous solvent mixtures. Our results elucidate the important roles of solvation, molecular packing dynamics, andmore » lateral charge)transfer mechanisms that have implications for all dye)sensitized photoelectrochemical device designs.« less

  9. Design and optimization of anode flow field of a large proton exchange membrane fuel cell for high hydrogen utilization

    NASA Astrophysics Data System (ADS)

    Yesilyurt, Serhat; Rizwandi, Omid

    2016-11-01

    We developed a CFD model of the anode flow field of a large proton exchange membrane fuel cell that operates under the ultra-low stoichiometric (ULS) flow conditions which intend to improve the disadvantages of the dead-ended operation such as severe voltage transient and carbon corrosion. Very small exit velocity must be high enough to remove accumulated nitrogen, and must be low enough to retain hydrogen in the active area. Stokes equations are used to model the flow distribution in the flow field, Maxwell-Stefan equations are used to model the transport of the species, and a voltage model is developed to model the reactions kinetics. Uniformity of the distribution of hydrogen concentration is quantified as the normalized area of the region in which the hydrogen mole fraction remains above a certain level, such as 0.9. Geometry of the anode flow field is modified to obtain optimal configuration; the number of baffles at the inlet, width of the gaps between baffles, width of the side gaps, and length of the central baffle are used as design variables. In the final design, the hydrogen-depleted region is less than 0.2% and the hydrogen utilization is above 99%. This work was supported by The Scientific and Technolo-gical Research Council of Turkey, TUBITAK-213M023.

  10. ECUT: Energy Conversion and Utilization Technologies program biocatalysis research activity. Potential membrane applications to biocatalyzed processes: Assessment of concentration polarization and membrane fouling

    NASA Technical Reports Server (NTRS)

    Ingham, J. D.

    1983-01-01

    Separation and purification of the products of biocatalyzed fermentation processes, such as ethanol or butanol, consumes most of the process energy required. Since membrane systems require substantially less energy for separation than most alternatives (e.g., distillation) they have been suggested for separation or concentration of fermentation products. This report is a review of the effects of concentration polarization and membrane fouling for the principal membrane processes: microfiltration, ultrafiltration, reverse osmosis, and electrodialysis including a discussion of potential problems relevant to separation of fermentation products. It was concluded that advanced membrane systems may result in significantly decreased energy consumption. However, because of the need to separate large amounts of water from much smaller amounts of product that may be more volatile than wate, it is not clear that membrane separations will necessarily be more efficient than alternative processes.

  11. Strain-Level Differences in Porphyrin Production and Regulation in Propionibacterium acnes Elucidate Disease Associations

    PubMed Central

    Johnson, Tremylla; Kang, Dezhi; Barnard, Emma

    2016-01-01

    ABSTRACT Propionibacterium acnes is an important skin commensal, but it is also considered a pathogenic factor in several diseases including acne vulgaris, the most common skin disease. While previous studies have revealed P. acnes strain-level differences in health and disease associations, the underlying molecular mechanisms remain unknown. Recently, we demonstrated that vitamin B12 supplementation increases P. acnes production of porphyrins, a group of proinflammatory metabolites important in acne development (D. Kang, B. Shi, M. C. Erfe, N. Craft, and H. Li, Sci. Transl. Med. 7:293ra103, 2015, doi:10.1126/scitranslmed.aab2009). In this study, we compared the porphyrin production and regulation of multiple P. acnes strains. We revealed that acne-associated type IA-2 strains inherently produced significantly higher levels of porphyrins, which were further enhanced by vitamin B12 supplementation. On the other hand, health-associated type II strains produced low levels of porphyrins and did not respond to vitamin B12. Using a small-molecule substrate and inhibitor, we demonstrated that porphyrin biosynthesis was modulated at the metabolic level. We identified a repressor gene (deoR) of porphyrin biosynthesis that was carried in all health-associated type II strains, but not in acne-associated type IA-2 strains. The expression of deoR suggests additional regulation of porphyrin production at the transcriptional level in health-associated strains. Our findings provide one potential molecular mechanism for the different contributions of P. acnes strains to skin health and disease and support the role of vitamin B12 in acne pathogenesis. Our study emphasizes the importance of understanding the role of the commensal microbial community in health and disease at the strain level and suggests potential utility of health-associated P. acnes strains in acne treatment. IMPORTANCE Propionibacterium acnes is a dominant bacterium residing on skin, and it has been thought

  12. Ultrasonic method for the preparation of organic porphyrin nanoparticles.

    PubMed

    Kashani-Motlagh, Mohamad Mehdi; Rahimi, Rahmatollah; Kachousangi, Marziye Javaheri

    2009-01-12

    We report the synthesis and optical properties of organic porphyrin nanoparticles with narrow size distribution and good dispersibility. Nanoparticles were produced by a combination of precipitation and sonication, termed the "ultrasonic method". The resulting [tetrakis(para-chlorophenyl)porphyrin]TClPP nanoparticles were stable in solution without precipitation for at least 30 days. No self aggregation of the constituent porphyrin chromophores was observed. The TClPP nanoparticles exhibited interesting optical properties, particularly a large bathochromic shift in the absorption spectra.

  13. Porphyrin-Embedded Silicate Materials for Detection of Hydrocarbon Solvents

    DTIC Science & Technology

    2011-01-14

    in the detection of gaseous pollutants: Detection of benzene using cationic porphyrins in polymer films . Sens. Actuat. B Chem. 1999, 54, 243-251. 2...porphyrin structure or incorporation of a metal into the central coordination site. Porphyrins are often incorporated into thin films for these sensing...900 equipped with an Optima-210 (50 m × 0.25 mm × 0.25 m film ) fused silica capillary column (Macherey-Nagel). GC instrument parameters were set for

  14. Langmuir-Blodgett films of amphiphilic push-pull porphyrins

    SciTech Connect

    Chou, H.; Chen, C.T.; Stork, K.F.; Bohn, P.W.; Suslick, K.S. )

    1994-01-13

    A series of nitrophenyl-amidophenyl-substituted porphyrins with n-C[sub 17]H[sub 35] tails have been synthesized and fully characterized. Good Langmuir-Blodgett films of these materials can be prepared on water and transferred successfully to glass slides. Mean molecular areas for the series were measured and found to increase from 80 to 230 A[sup 2] as the number of aliphatic chains increased from one to four. As determined by linear dichroic measurements, this change in area does not correspond to a change in the orientation of the porphyrin with respect to the surface. In the absence of the steric constraints of multiple aliphatic chains, porphyrin-porphyrin stacking permits close packing of the rings. As the number of aliphatic chains on the porphyrin periphery increases, however, the porphyrin planes must pack more loosely. Thus, the porphyrin macrocycle orientation is determined by interactions between porphyrin rings and between porphyrins and the aqueous (or polar glass) surface. In contrast, the differences in the observed mean molecular area are determined independently by packing constraints imposed by the pendant hydrocarbon chains. 13 refs., 3 figs., 1 tab.

  15. Water-splitting using photocatalytic porphyrin-nanotube composite devices

    DOEpatents

    Shelnutt, John A.; Miller, James E.; Wang, Zhongchun; Medforth, Craig J.

    2008-03-04

    A method for generating hydrogen by photocatalytic decomposition of water using porphyrin nanotube composites. In some embodiments, both hydrogen and oxygen are generated by photocatalytic decomposition of water.

  16. Managing the extracorporeal membrane oxygenation (ECMO) circuit integrity and safety utilizing the perfusionist as the "ECMO Specialist".

    PubMed

    Mongero, L B; Beck, J R; Charette, K A

    2013-11-01

    Extracorporeal membrane oxygenation (ECMO) is an extracorporeal technique of providing both cardiac and respiratory support to patients whose heart and lungs are so severely diseased or damaged that they can no longer serve their function. Neonatal and pediatric ECMO was accepted as practice in the early 1990s and according to the Extracorporeal Life Support Organization, ELSO; of the >50,000 patients registered, 73% have survived extracorporeal life support (ECLS). It is not uncommon to find initial cannulation of a patient receiving ECMO performed by a surgeon and then the maintenance of the patient being left in the hands of various others deemed as the "ECMO Specialists". The specialist has a broad base of professionals, including: nurses, respiratory therapists, perfusionists and physicians. Each institution, having its own unique training for these individuals, has provided a milieu for education, but does not share an established standard of care. From 2009, after the surge of the H1N1 epidemic, adult ECMO has been increasing; n=53 in 2010 to n=110 in 2012 at our institution. The perfusionist has been the "specialist" for ECMO at our institution since the early 1990s and remained at bedside during ECMO. We have now developed a safe circuit and fiscally responsible staffing model that utilizes a perfusionist and a telemetry-based electronic record keeper, permitting the perfusionist to leave the bedside and interact with the circuit when necessary. This has permitted an expansive growth of ECMO in our intensive care units at our facility incorporating a multidisciplinary collaboration system wide.

  17. Utilization of pyrolytic substrate by microalga Chlamydomonas reinhardtii: cell membrane property change as a response of the substrate toxicity.

    PubMed

    Zhao, Xuefei; Jarboe, Laura; Wen, Zhiyou

    2016-05-01

    Acetic acid derived from fast pyrolysis of lignocellulosic biomass is a promising substrate for microalgae fermentation for producing lipid-rich biomass. However, crude pyrolytic acetic acid solution contains various toxic compounds inhibiting algal growth. It was hypothesized that such an inhibition was mainly due to the cell membrane damage. In this work, the cell membrane property of algal cells was evaluated at various conditions to elucidate the mechanisms of inhibition caused by the pyrolytic substrate solution. It was found that acetic acid itself served a carbon source for boosting algal cell growth but also caused cell membrane leakage. The acetic acid concentration for highest cell density was 4 g/L. Over-liming treatment of crude pyrolytic acetic acid increased the algal growth with a concurrent reduction of cell membrane leakage. Directed evolution of algal strain enhanced cell membrane integrity and thus increased its tolerance to the toxicity of the crude substrate. Statistical analysis shows that there was a significant correlation between the cell growth performance and the cell membrane integrity (leakage) but not membrane fluidity. The addition of cyto-protectants such as Pluronic F68 and Pluronic F127 enhanced the cell membrane integrity and thus, resulted in enhanced cell growth. The transmission electron microscopy (TEM) of algal cells visually confirmed the cell membrane damage as the mechanism of the pyrolytic substrate inhibition. Collectively, this work indicates that the cell membrane is one major reason for the toxicity of pyrolytic acetic acid when being used for algal culture. To better use this pyrolytic substrate, cell membrane of the microorganism needs to be strengthened through either strain improvement or addition of membrane protectant reagents.

  18. Past and future: porphyria and porphyrins.

    PubMed

    Norman, Robert A

    2005-01-01

    Porphyria is a compelling disease--disrupted enzyme pathways, heightened sensitivities, and a fascinating history tied in with tales of Dracula. This review discusses the history, pathophysiology, classification, and treatment of porphyria. It further discusses the way in which research on the etiologies of the various porphyrias has led to the development of porphyrin-based photodynamic therapy, which shows great promise in targeted therapy for a variety of serious pathologies.

  19. Synthesis and cellular localization of porphyrinic pigments

    NASA Astrophysics Data System (ADS)

    Sareh, Sarah; Kong, Sarah; Parrales, Lenin; Jung, Anna; Cross, Kara; Röder, Beate; Isaac, Meden; Simonis, Ursula

    2009-06-01

    To determine factors that govern the uptake preference of photosensitizers in cellular organelles of human adenocarcinoma cells, diarginyl-dialkoxy- and diarginyl-dimethoxyphenylporphyrins (TPPs) and two of their corresponding indium(III) complexes were synthesized, characterized and incubated in androgen-sensitive human prostate adenocarcinoma cells LNCaP. The porphyrins revealed properties that are of importance for phototherapy. They are water-soluble, have their fourth Q-band absorbing at ~ 650 nm, are taken up in relatively high concentrations in LNCaP cells, and are phototoxic. Colocalization and phototoxicity studies revealed that all porphyrins localized preferentially to the lysosomes and invoked cell death when excited with 650 nm light. Compared to the corresponding methoxy-substituted TPPs, the diargininyl-dialkoxy-substituted porphyrins localized to a small extent in the mitochondria. The corresponding In(III) chloride complexes that are slightly less water-soluble were also taken up in the lysosomes of LnCaP cells. When the TPPs were compared to a pheophorbide derivative recently synthesized in our laboratory, it was determined that the TPPs have a preference for lysosomal localization, whereas the pheophorbide derivative co-localized to the mitochondria. Phototoxicity studies revealed that the longer chain dialkoxyTPPs were more effective in cell killing and induced greater morphological changes typical of apoptotic cell death than the shorter chain methoxy substituted porphyrins. The In(III) complexes seemed to be the most phototoxic. These results highlight that the type, nature, and substitution pattern of the chromophore modulate the extent of apoptotic cell death and influence cellular targeting.

  20. Hydrosulfide (HS−) Coordination in Iron Porphyrinates

    PubMed Central

    Pavlik, Jeffrey W.; Noll, Bruce C.; Oliver, Allen G.; Schulz, Charles E.; Scheidt, W. Robert

    2010-01-01

    Recent reports of potential physiological roles of hydrogen sulfide have prompted interest in heme-sulfide interactions. Heme-H2S and/or heme-HS− interactions could potentially occur during endogenous production, transport, signaling events, and catabolism of H2S. We have investigated the interaction of the hydrosulfide ion (HS−) with iron porphyrinates. UV-vis spectral studies show the formation of [Fe(Por)(SH)]−, [Fe(Por)(SH)2]2−, and the mixed ligand species [Fe(Por)(Im)(SH)]−. UV-vis binding studies of [Fe(OEP)] and [Fe(Tp-OMePP)] (OEP = octaethylporphyrinate, Tp-OMePP = tetra-p-methoxyphenylporphyrinate) with HS− allowed for calculation of formation constants and extinction coefficients of the mono- and bis-HS− complexes. We report the synthesis of the first HS− bound iron(II) porphyrin compounds, [Na(222)][Fe(OEP)(SH)]·0.5C6H6 and [Na(222)][Fe(Tp-OMePP)(SH)]·C6H5Cl (222 = kryptofix-222). Characterization by single-crystal X-ray analysis, mass spectrometry, and Mössbauer and IR spectroscopy are all consistent with that of known sulfur-bound high-spin iron(II) compounds. The Fe–S distances of 2.3929(5) and 2.3887(13) Å are longer than all reported values of [FeII(Por)(SR)]− species. An analysis of porphyrin non-planarity for these derivatives and for all five-coordinate high-spin iron(II) porphyrinate derivatives with an axial anion ligand is presented. In our hands, attempts to synthesize iron(III) HS− derivatives led to iron(II) species. PMID:20038134

  1. Photobiological activity of exogenous and endogenous porphyrin derivatives in Escherichia coli and Enterococcus hirae cells.

    PubMed

    Gábor, F; Szocs, K; Maillard, P; Csík, G

    2001-06-01

    Photodynamic treatment, the combined application of a photosensitiser and visible light, represents a new and promising approach for the inactivation of microorganisms. The photosensitising potentials of exogenous zinc-phthalocyanine-tetrasulphonate (ZnPsTS), tetraphenylporphyrins (TPPs) and endogenous porphyrin derivatives were tested and compared on Gram-negative and Gram-positive bacteria, Escherichia coli B. and Enterococcus hirae, respectively. The synthesis of endogenous porphyrins was induced by 5-aminolevulinic acid (delta-ALA). The porphyrin- or delta-ALA-treated cells were irradiated with white light. The photosensitising efficiency of endogenous derivatives on both types of bacteria is ZnPcTS < TP(4-OGluOH)3P < TP(4-OGluOH)4P. However, neither exogenous derivatives exhibit appreciable photosensitising activity for disinfection application. ALA-induced photodynamic treatment showed good potential for the inactivation of Escherichia coli cells, but not towards Enterococcus hirae cells. The failure of photosensitisation of the Enterococcus hirae strain selected indicates that apart from the Gram-positive character, other structural elements of the membrane can influence the result of photodynamic treatments.

  2. Porphyrin photosensitivity in cell lines expressing a heat-resistant phenotype

    NASA Astrophysics Data System (ADS)

    Gomer, Charles J.; Rucker, Natalie; Wong, Sam

    1990-07-01

    In-vitro sensitivity to porphyrin mediated photodynamic therapy (PDT) has been examined in cell lines resistant to hyperthermia. Parental (HA-i) and heat resistant (3012) Chinese hamster fibroblasts as well as parental (RIF-i) and temperature resistant (TR-4, TR-5 and TR-iO) mouse radiation-induced fibrosarcoma cells were evaluated for thermal and PDT sensitivity. Quantitative survival curves were generated and porphyrin uptake properties were obtained for all cell lines. Significant resistance to hyperthermia (450C for varying exposure periods) was documented for the 3012 and TR cell strains when compared to 'the parent lines. However, normal and heat resistant clones exhibited comparable levels of porphyrin uptake and photosensitivity. Our results indicate that cross resistance between hyperthermia and PDT is not observed and that members of the 70 kD heat shock protein family (which are elevated in the thermal resistant cells and may be associated with the heat resistant phenotype) do not play a significant role in modulating PDT sensitivity. Mechanisms of in-vitro cytotoxicity appear to be different for PDT and hyperthermia even though possible subcellular targets (such as the plasma membrane) and types of damage (protein denaturation) may be similar for the two modalities.

  3. Porphyrin Based Near Infrared-Absorbing Materials for Organic Photovoltaics

    NASA Astrophysics Data System (ADS)

    Zhong, Qiwen

    photosynthesis. Photosynthesis uses light from the sun to drive a series of chemical reactions. Most natural photosynthetic systems utilize chlorophylls to absorb light energy and carry out photochemical charge separation that stores energy in the form of chemical bonds. The sun produces a broad spectrum of light output that ranges from gamma rays to radio waves. The entire visible range of light (400-700 nm) and some wavelengths in the NIR (700-1000 nm), are highly active in driving photosynthesis. Although the most familiar chlorophyll-containing organisms, such as plants, algae and cyanobacteria, cannot use light longer than 700 nm, anoxygenic bacterium containing bacteriochlorophylls can use the NIR part of the solar spectrum. No organism is known to utilize light of wavelength longer than about 1000 nm for photosynthesis. NIR light has a very low-energy content in each photon, so that large numbers of these low-energy photons would have to be used to drive the chemical reactions of photosynthesis. This is thermodynamically possible but would require a fundamentally different molecular mechanism that is more akin to a heat engine than to photochemistry. Early work on developing light absorbing materials for OPVs was inspired by photosynthesis in which light is absorbed by chlorophyll. Structurally related to chlorophyll is the porphyrin family, which has accordingly drawn much interest as the potential light absorbing component in OPV applications. In this dissertation, the design and detail studies of several porphyrin-based NIR absorbing materials, including pi--extended perylenyl porphryins and pyrazole-containing carbaporphyrins, as well as porphyrin modified single-walled carbon nanotube hybrids, will be presented, dedicating efforts to develop novel and application-oriented materials for efficient utilization of sustainable solar energy.

  4. "Spider"-shaped porphyrins with conjugated pyridyl anchoring groups as efficient sensitizers for dye-sensitized solar cells.

    PubMed

    Stangel, Christina; Bagaki, Anthi; Angaridis, Panagiotis A; Charalambidis, Georgios; Sharma, Ganesh D; Coutsolelos, Athanasios G

    2014-11-17

    Two novel "spider-shaped" porphyrins, meso-tetraaryl-substituted 1PV-Por and zinc-metalated 1PV-Zn-Por, bearing four oligo(p-phenylenevinylene) (oPPV) pyridyl groups with long dodecyloxy chains on the phenyl groups, have been synthesized. The presence of four pyridyl groups in both porphyrins, which allow them to act as anchoring groups upon coordination to various Lewis acid sites, the conjugated oPPV bridges, which offer the possibility of electronic communication between the porphyrin core and the pyridyl groups, and the dodecyloxy groups, which offer the advantage of high solubility in a variety of organic solvents of different polarities and could prevent porphyrin aggregation, renders porphyrins 1PV-Por and 1PV-Zn-Por very promising sensitizers for dye-sensitized solar cells (DSSCs). Photophysical measurements, together with electrochemistry experiments and density functional theory calculations, suggest that both porphyrins have frontier molecular orbital energy levels that favor electron injection and dye regeneration in DSSCs. Solar cells sensitized by 1PV-Por and 1PV-Zn-Por were fabricated, and it was found that they show power conversion efficiencies (PCEs) of 3.28 and 5.12%, respectively. Photovoltaic measurements (J-V curves) together with incident photon-to-electron conversion efficiency spectra of the two cells reveal that the higher PCE value of the DSSC based on 1PV-Zn-Por is ascribed to higher short-circuit current (Jsc), open-circuit voltage (Voc), and dye loading values. Emission spectra and electrochemistry experiments suggest a greater driving force for injection of the photogenerated electrons into the TiO2 conduction band for 1PV-Zn-Por rather than its free-base analogue. Furthermore, electrochemical impedance spectroscopy measurements prove that the utilization of 1PV-Zn-Por as a sensitizer offers a high charge recombination resistance and, therefore, leads to a longer electron lifetime.

  5. Synthesis, antinociceptive and anti-inflammatory effects of porphyrins.

    PubMed

    Alonso-Castro, Angel Josabad; Zapata-Morales, Juan Ramón; Hernández-Munive, Abigail; Campos-Xolalpa, Nimsi; Pérez-Gutiérrez, Salud; Pérez-González, Cuauhtémoc

    2015-05-15

    Porphyrins are natural compounds with several biological activities. We report the synthesis and the evaluation of the anti-inflammatory and antinociceptive effects of 4 porphyrins: 5,10,15,20-tetraphenylporphyrin (TPP), 5,10,15,20-tetra(4'-fluorophenyl)porphyrin (TpFPP), 5,10,15,20-tetra(4'-chlorophenyl)porphyrin (TpClPP), and 5,10,15,20-tetra(4'-bromophenyl)porphyrin (TpBrPP). The in vitro anti-inflammatory effects were evaluated on heat-induced hemolysis. The antinociceptive effects were evaluated using the hot plate and formalin tests. The in vivo anti-inflammatory assays were tested on the acute and chronic TPA (12-O-tetradecanoylphorbol 13-acetate) method to induce ear edema. The anti-arthritic effects were evaluated using carrageenan kaolin induced arthritis (CKIA). All porphyrins inhibited hemolysis with similar potency than naproxen (NPX). In the antinociceptive tests, all porphyrins tested at 200mg/kg showed similar effects compared to 100mg/kg NPX. In the in vivo anti-inflammatory acute assay, only three porphyrins (TPP, TpFPP and TpBrPP) decreased inflammation with similar activity than 2mg/ear indomethacin (IND). Further anti-inflammatory experiments were carried out with TPP, TpFPP and TpBrPP. In the in vivo anti-inflammatory chronic assay, porphyrins decreased inflammation with similar activity than 8mg/kg IND. Porphyrins tested at 200mg/kg showed anti-arthritic effects. The antinociceptive, anti-inflammatory and arthritic activities of porphyrins suggest that these compounds might be a good alternative for the treatment of inflammatory diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Photochemical solar energy conversion utilizing semiconductors localized in membrane mimetic systems: Comprehensive progress report, April 1, 1986--September 30, 1988

    SciTech Connect

    Fendler, J.H.

    1988-01-01

    This paper contain topics on photochemical solar energy conversion in the following areas: preparation and characterization of vesicles and polymerized vesicles; preparation and characterization of bilayer lipid membranes; dispersed colloidal semiconductors; semiconductor-particle-mediated photoconversion in vesicles and polymerized vesicles; and semiconductor-particle-mediated photoconversion in bilayer lipid membranes. 3 figs.

  7. Hole transport in porphyrin thin films

    NASA Astrophysics Data System (ADS)

    Savenije, Tom J.; Goossens, Albert

    2001-09-01

    Hole transport in p-type organic semiconductors is a key issue in the development of organic electronic devices. Here the diffusion of holes in porphyrin thin films is investigated. Smooth anatase TiO2 films are coated with an amorphous thin film of zinc-tetra(4-carboxyphenyl) porphyrin (ZnTCPP) molecules acting as sensitizer. Optical excitation of the porphyrin stimulates the injection of electrons into the conduction band of TiO2. The remaining holes migrate towards the back electrode where they are collected. Current-voltage and capacitance-voltage analysis reveal that the TiO2/ZnTCPP system can be regarded as an n-p heterojunction, with a donor density of ND=2.0×1016 cm-3 for TiO2 and an acceptor density NA=4.0×1017 cm-3 for ZnTCPP films. The acceptor density in porphyrin films increases to 1.3×1018 cm-3 upon irradiation with 100-mW cm-2 white light. Intensity-modulated photocurrent spectroscopy, in which ac-modulated irradiation is applied, is used to measure the transit times of the photogenerated holes through the films. A reverse voltage bias hardly affects the transit time, whereas a small forward bias yields a decrease of the transit time by two orders of magnitude. Application of background irradiation also reduces the transit time considerably. These observations are explained by the presence of energy fluctuation of the highest-occupied molecular orbital level in the porphyrin films due to a dispersed conformational state of the molecules in the amorphous films. This leads to energetically distributed hole traps. Under short circuit and reverse bias, photogenerated holes reside most of the time in deep traps and their diffusivity is only 7×10-11 cm2 s-1. Deep traps are filled by application of a forward bias and by optical irradiation leading to reduction of the transit time and a concomitant increase of the diffusivity up to 2×10-7 cm2 s-1.

  8. Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, P.E. Jr.; Lyons, J.E.

    1995-01-17

    New compositions of matter comprising cyano-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has cyano groups attached thereto in meso and/or [beta]-pyrrolic positions.

  9. Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, P.E. Jr.; Lyons, J.E.

    1993-05-18

    New compositions of matter comprising cyano-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has cyano groups attached thereto in meso- and/or [beta]-pyrrolic positions.

  10. Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, Jr., Paul E.; Lyons, James E.

    1995-01-01

    New compositions of matter comprising cyano-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has cyano groups attached thereto in meso and/or .beta.-pyrrolic positions.

  11. Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, Jr., Paul E.; Lyons, James E.

    1993-01-01

    New compositions of matter comprising cyano-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has cyano groups attached thereto in meso and/or .beta.-pyrrolic positions.

  12. Fusion and planarization of a quinoidal porphyrin dimer.

    PubMed

    Blake, Iain M; Krivokapic, Alexander; Katterle, Martin; Anderson, Harry L

    2002-08-21

    The crystal structure, near-infrared spectrum and electrochemistry of a quinoidal triply-linked porphyrin dimer are compared with those of its singly-linked precursor; fusing the two porphyrins planarizes the pi-system and reduces the optical HOMO-LUMO gap while increasing the gap between the first oxidation and reduction potentials.

  13. Photocontrol over cooperative porphyrin self-assembly with phenylazopyridine ligands.

    PubMed

    Hirose, Takashi; Helmich, Floris; Meijer, E W

    2013-01-02

    The cooperative self-assembly of chiral zinc porphyrins is regulated by a photoresponsive phenylazopyridine ligand. Porphyrin stacks depolymerize into dimers upon axial ligation and the strength of the coordination is regulated by its photoinduced isomerization, which shows more than 95 % conversion ratio for both photostationary states.

  14. Porphyrin-based sensor nanoarchitectonics in diverse physical detection modes.

    PubMed

    Ishihara, Shinsuke; Labuta, Jan; Van Rossom, Wim; Ishikawa, Daisuke; Minami, Kosuke; Hill, Jonathan P; Ariga, Katsuhiko

    2014-06-07

    Porphyrins and related families of molecules are important organic modules as has been reflected in the award of the Nobel Prizes in Chemistry in 1915, 1930, 1961, 1962, 1965, and 1988 for work on porphyrin-related biological functionalities. The porphyrin core can be synthetically modified by introduction of various functional groups and other elements, allowing creation of numerous types of porphyrin derivatives. This feature makes porphyrins extremely useful molecules especially in combination with their other interesting photonic, electronic and magnetic properties, which in turn is reflected in their diverse signal input-output functionalities based on interactions with other molecules and external stimuli. Therefore, porphyrins and related macrocycles play a preeminent role in sensing applications involving chromophores. In this review, we discuss recent developments in porphyrin-based sensing applications in conjunction with the new advanced concept of nanoarchitectonics, which creates functional nanostructures based on a profound understanding of mutual interactions between the individual nanostructures and their arbitrary arrangements. Following a brief explanation of the basics of porphyrin chemistry and physics, recent examples in the corresponding fields are discussed according to a classification based on physical modes of detection including optical detection (absorption/photoluminescence spectroscopy and energy and electron transfer processes), other spectral modes (circular dichroism, plasmon and nuclear magnetic resonance), electronic and electrochemical modes, and other sensing modes.

  15. Photodynamic inactivation of Penicillium chrysogenum conidia by cationic porphyrins.

    PubMed

    Gomes, Maria C; Woranovicz-Barreira, Sandra M; Faustino, Maria A F; Fernandes, Rosa; Neves, Maria G P M S; Tomé, Augusto C; Gomes, Newton C M; Almeida, Adelaide; Cavaleiro, José A S; Cunha, Angela; Tomé, João P C

    2011-11-01

    This work reports the photophysical and biological evaluation of five cationic porphyrins as photosensitizers (PS) for the photodynamic inactivation (PDI) of Penicillium chrysogenum conidia. Two different cationic porphyrin groups were synthesized from 5,10,15,20-tetrakis(4-pyridyl)porphyrin and 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin. The photostability and singlet oxygen generation studies showed that these molecules are photostable and efficient singlet oxygen generators. PDI experiments of P. chrysogenum conidia conducted with 50 μmol L(-1) of photosensitiser under white light at a fluence rate of 200 mW cm(-2) over 20 min showed that the most effective PS caused a 4.1 log reduction in the concentration of viable conidia. The present results show that porphyrins 1a and 1b are more efficient PSs than porphyrin 2a while porphyrins 1c and 2b show no inactivation of P. chrysogenum. It is also clear that the effectiveness of the molecule as PS for antifungal PDI is strongly related with the porphyrin substituent groups, and consequently their solubility in physiological media. The average amount of PS adsorbed per viable conidium was a determining factor in the photoinactivation efficiency and varied between the different studied PSs. Cationic PSs 1a and 1b might be promising anti-fungal PDI agents with potential applications in phytosanitation, biofilm control, bioremediation, and wastewater treatment.

  16. Utilization of a multimembrane inlet and a cyclic sudden sampling introduction mode in membrane inlet mass spectrometry.

    PubMed

    Viktorova, O S; Kogan, V T; Manninen, S A; Kotiaho, T; Ketola, R A; Dubenskii, B M; Parinov, S P; Smirnov, O V

    2004-06-01

    Sudden sampling introduction into a membrane inlet mass spectrometer (MIMS) considerably improves the selectivity of the membrane inlet and is therefore applicable even for compounds with low permeabilities through a silicone membrane. In this study the basics of cyclic non-steady-state sudden increase sample injection were studied using a three-membrane inlet and a portable sector double-focusing mass spectrometer. The operational parameters of the inlet system providing the most efficient enrichment of volatile organic compounds (VOCs) in air were defined. Simulation of the diffusion process following sudden sample introduction into the three-membrane inlet was also carried out. Experimental testing of the three-membrane inlet system with the cyclic sudden sample injection mode for benzene, toluene, styrene, and xylene in air was performed. The simulation and the experimental results demonstrated that, when this mode is used, the VOCs/nitrogen relative enrichment factor of samples introduced into the mass spectrometer equipped with a three-membrane inlet is increased by a factor of approximately 10(5) compared with a direct introduction method. This effect may be used to decrease detection limits of compounds obtained with mass spectrometry to decrease matrix flow through the inlet at the same detection limits.

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

    PubMed

    Milot, Rebecca L; Schmuttenmaer, Charles A

    2015-05-19

    There is a growing need to utilize carbon neutral energy sources, and it is well known that solar energy can easily satisfy all of humanity's requirements. In order to make solar energy a viable alternative to fossil fuels, the problem of intermittency must be solved. Batteries and supercapacitors are an area of active research, but they currently have relatively low energy-to-mass storage capacity. An alternative and very promising possibility is to store energy in chemical bonds, or make a solar fuel. The process of making solar fuel is not new, since photosynthesis has been occurring on earth for about 3 billion years. In order to produce any fuel, protons and electrons must be harvested from a species in its oxidized form. Photosynthesis uses the only viable source of electrons and protons on the scale needed for global energy demands: water. Because artificial photosynthesis is a lofty goal, water oxidation, which is a crucial step in the process, has been the initial focus. This Account provides an overview of how terahertz spectroscopy is used to study electron injection, highlights trends from previously published reports, and concludes with a future outlook. It begins by exploring similarities and differences between dye-sensitized solar cells (DSSCs) for producing electricity and a putative device for splitting water and producing a solar fuel. It then identifies two important problems encountered when adapting DSSC technology to water oxidation-improper energy matching between sensitizer energy levels with the potential for water oxidation and the instability of common anchoring groups in water-and discusses steps to address them. Emphasis is placed on electron injection from sensitizers to metal oxides because this process is the initial step in charge transport. Both the rate and efficiency of electron injection are analyzed on a sub-picosecond time scale using time-resolved terahertz spectroscopy (TRTS). Bio-inspired pentafluorophenyl porphyrins are

  18. Photochemistry of porphyrins: a model for the origin of photosynthesis

    NASA Technical Reports Server (NTRS)

    Mercer-Smith, J. A.; Mauzerall, D. C.

    1984-01-01

    A series of porphyrins and catalysts has been prepared as a model for the origin of photosynthesis on the primordial earth. These compounds have been used to test the hypotheses that (1) the biosynthetic pathway to chlorophyll recapitulates the evolutionary history of photosynthesis, and (2) the proto-photosythetic function of biogenetic porphyrins (biosynthetic chlorophyll precursors) was the oxidation of organic molecules by photoexcited porphyrins with the attendant emission of molecular hydrogen. This paper describes experiments in which photoexcited biogenetic porphyrins oxidize ethylenediamine tetraacetic acid (EDTA). The concomitant reduction of protons to hydrogen gas occurs in the presence of a colloidal platinum catalyst. The addition of methyl viologen, a one-electron shuttle, increases the amount of molecular hydrogen generated during long irradiations and the quantum yield of hydrogen production. When the porphyrin and catalyst are held in association by molecular complexes, the increased efficiency of electron transfer produces higher yields of hydrogen gas.

  19. Photochemistry of porphyrins: a model for the origin of photosynthesis

    NASA Technical Reports Server (NTRS)

    Mercer-Smith, J. A.; Mauzerall, D. C.

    1984-01-01

    A series of porphyrins and catalysts has been prepared as a model for the origin of photosynthesis on the primordial earth. These compounds have been used to test the hypotheses that (1) the biosynthetic pathway to chlorophyll recapitulates the evolutionary history of photosynthesis, and (2) the proto-photosythetic function of biogenetic porphyrins (biosynthetic chlorophyll precursors) was the oxidation of organic molecules by photoexcited porphyrins with the attendant emission of molecular hydrogen. This paper describes experiments in which photoexcited biogenetic porphyrins oxidize ethylenediamine tetraacetic acid (EDTA). The concomitant reduction of protons to hydrogen gas occurs in the presence of a colloidal platinum catalyst. The addition of methyl viologen, a one-electron shuttle, increases the amount of molecular hydrogen generated during long irradiations and the quantum yield of hydrogen production. When the porphyrin and catalyst are held in association by molecular complexes, the increased efficiency of electron transfer produces higher yields of hydrogen gas.

  20. Facile synthesis of peptide-porphyrin conjugates: Towards artificial catalase.

    PubMed

    Umezawa, Naoki; Matsumoto, Nobuyoshi; Iwama, Shinsuke; Kato, Nobuki; Higuchi, Tsunehiko

    2010-09-01

    A facile synthetic method for peptide-porphyrin conjugates containing four peptide units on one porphyrin was developed using chemoselective reactions. The key building blocks, 5,10,15,20-tetrakis(3-azidophenyl)porphyrin 1 and 5,10,15,20-tetrakis(5-azido-3-pyridyl)porphyrin 2, were efficiently synthesized and used as substrates for two well-known chemoselective reactions, traceless Staudinger ligation and copper-catalyzed azide alkyne cycloaddition (so-called click chemistry). Both reactions gave the desired compounds, and click chemistry was superior for our purpose. To confirm the value of the established methodology, nine peptide-porphyrin conjugates were synthesized, and their catalase- and peroxidase-like activity in water was evaluated. Our synthetic strategy is expected to be valuable for the preparation of artificial heme protein models. Copyright 2010 Elsevier Ltd. All rights reserved.

  1. Hydration of porphyrin and Mg-porphyrin: ab initio quantum mechanical charge field molecular dynamics simulations.

    PubMed

    Moin, Syed Tarique; Hofer, Thomas S

    2014-01-01

    Ab initio QMCF-MD simulations were performed for porphyrin (POR) and magnesium-porphyrin (Mg-POR) immersed in water to study their structural and dynamical properties. The observed hydration behaviour of these solutes representing biomimetic models is in fair agreement with structural and dynamical features of their biological analogues, protoporphyrin IX (PPIX) and chlorophyll (CHl). Structural data obtained from the radial, angular and spatial distribution functions as well as the angular-radial distributions have a consensus on possessing a contrasting hydration behaviour of POR and Mg-POR. Flexibility of the ring in both solutes described by the improper torsional distribution and root mean square fluctuation showed an influence on H-bond interactions between the nitrogen atoms and water molecules that are also reflected in the respective dynamics. An axial water molecule coordinated to the Mg(ii) ion indicates the penta-coordinated Mg-POR to be stable along the simulation. It was also shown that complexation of the Mg(ii) ion to the porphyrin influences the hydration patterns significantly compared to the porphyrin itself, which is further supported by the vibrational power spectra evaluated for both solutes. Free energy of binding and solvent accessible surface area calculations also confirmed that these two solutes have distinct hydration behaviour. Detailed knowledge of the individual hydration patterns is expected to be of particular benefit.

  2. Porphyrin-Metalation-Mediated Tuning of Photoredox Catalytic Properties in Metal–Organic Frameworks

    SciTech Connect

    Johnson, Jacob A.; Luo, Jian; Zhang, Xu; Chen, Yu-Sheng; Morton, Martha D.; Echeverría, Elena; Torres, Fernand E.; Zhang, Jian

    2015-09-04

    Photoredox catalytic activation of organic molecules via single-electron transfer processes has proven to be a mild and efficient synthetic methodology. However, the heavy reliance on expensive ruthenium and iridium complexes limits their applications for scale-up synthesis. To this end, photoactive metal–organic frameworks (MOFs) exhibit unique advantages as novel heterogeneous photocatalytic systems, yet their utilization toward organic transformations has been limited. Here we describe the preparation and synthetic applications of four isostructural porphyrinic MOFs, namely, UNLPF-10a, -10b, -11, and -12, which are composed of free base, InIII-, SnIVCl2-, and SnIV-porphyrin building blocks, respectively. We demonstrate that the metalation with high valent metal cations (InIII and SnIV) significantly modifies the electronic structure of porphyrin macrocycle and provides a highly oxidative photoexcited state that can undergo efficient reductive quenching processes to facilitate organic reactions. In particular, UNLPF-12 exhibits both outstanding photostability and efficient photocatalytic activities toward a range of important organic transformations including aerobic hydroxylation of arylboronic acids, amine coupling, and the Mannich reaction.

  3. Synthesis and optical properties of hybrid gold nanoparticles coupled with quantum dots and porphyrins

    NASA Astrophysics Data System (ADS)

    Tobias, Andrew Kevin, Jr.

    Coupling of optically active materials, or chromphores, to plasmonic nanoparticles represents a new research area which has the ability to produce higher efficiency lighting and photovoltaic materials. The main goal of this project was to create novel systems for plasmonic coupling of different chromophores to gold nanoparticles. The plasmonic platforms utilized were gold nanoparticles coated in semiconductor shells of cadmium sulfide or zinc sulfide. The crystalline, semiconductor shell acts as a dielectric spacer to separate the chromophore from the metal surface. Intimate contact to the metal surface may result in increased energy transfer and nonradiative relaxation mechanisms, resulting in shorts for photovoltaic devices and quenching in applications using light emission. Plasmonically enhanced photo-absorbers can be used to boost the collected photocurrent in photovoltaic applications while enhanced fluorescent materials can be used in imaging or display technologies in which bright and stable, solution-state materials are needed. Quantum dots were linked to the nanoparticle surface, via a carbodiimide linking process. The thickness of the shell was then altered to optimize the spacing distance needed to maximize the quantum dot radiative rate. Porphyrins were linked to the surface of the semiconductor shell via deprotonated phenyl acid groups, located on the 5,10,15 or 20 positions of tetraphenyl porphyrin. Enhancements in the porphyrin extinction coefficient when bound to the nanoparticles were estimated through analysis of the absorbance spectral changes.

  4. Urinary Porphyrin Excretion in Neurotypical and Autistic Children

    PubMed Central

    Woods, James S.; Armel, Sarah E.; Fulton, Denise I.; Allen, Jason; Wessels, Kristine; Simmonds, P. Lynne; Granpeesheh, Doreen; Mumper, Elizabeth; Bradstreet, J. Jeffrey; Echeverria, Diana; Heyer, Nicholas J.; Rooney, James P.K.

    2010-01-01

    Background Increased urinary concentrations of pentacarboxyl-, precopro- and copro-porphyrins have been associated with prolonged mercury (Hg) exposure in adults, and comparable increases have been attributed to Hg exposure in children with autism (AU). Objectives This study was designed to measure and compare urinary porphyrin concentrations in neurotypical (NT) children and same-age children with autism, and to examine the association between porphyrin levels and past or current Hg exposure in children with autism. Methods This exploratory study enrolled 278 children 2–12 years of age. We evaluated three groups: AU, pervasive developmental disorder-not otherwise specified (PDD-NOS), and NT. Mothers/caregivers provided information at enrollment regarding medical, dental, and dietary exposures. Urine samples from all children were acquired for analyses of porphyrin, creatinine, and Hg. Differences between groups for mean porphyrin and Hg levels were evaluated. Logistic regression analysis was conducted to determine whether porphyrin levels were associated with increased risk of autism. Results Mean urinary porphyrin concentrations are naturally high in young children and decline by as much as 2.5-fold between 2 and 12 years of age. Elevated copro- (p < 0.009), hexacarboxyl- (p < 0.01) and pentacarboxyl- (p < 0.001) porphyrin concentrations were significantly associated with AU but not with PDD-NOS. No differences were found between NT and AU in urinary Hg levels or in past Hg exposure as determined by fish consumption, number of dental amalgam fillings, or vaccines received. Conclusions These findings identify disordered porphyrin metabolism as a salient characteristic of autism. Hg exposures were comparable between diagnostic groups, and a porphyrin pattern consistent with that seen in Hg-exposed adults was not apparent. PMID:20576582

  5. Urinary porphyrin excretion in neurotypical and autistic children.

    PubMed

    Woods, James S; Armel, Sarah E; Fulton, Denise I; Allen, Jason; Wessels, Kristine; Simmonds, P Lynne; Granpeesheh, Doreen; Mumper, Elizabeth; Bradstreet, J Jeffrey; Echeverria, Diana; Heyer, Nicholas J; Rooney, James P K

    2010-10-01

    Increased urinary concentrations of pentacarboxyl-, precopro- and copro-porphyrins have been associated with prolonged mercury (Hg) exposure in adults, and comparable increases have been attributed to Hg exposure in children with autism (AU). This study was designed to measure and compare urinary porphyrin concentrations in neurotypical (NT) children and same-age children with autism, and to examine the association between porphyrin levels and past or current Hg exposure in children with autism. This exploratory study enrolled 278 children 2-12 years of age. We evaluated three groups: AU, pervasive developmental disorder-not otherwise specified (PDD-NOS), and NT. Mothers/caregivers provided information at enrollment regarding medical, dental, and dietary exposures. Urine samples from all children were acquired for analyses of porphyrin, creatinine, and Hg. Differences between groups for mean porphyrin and Hg levels were evaluated. Logistic regression analysis was conducted to determine whether porphyrin levels were associated with increased risk of autism. Mean urinary porphyrin concentrations are naturally high in young children and decline by as much as 2.5-fold between 2 and 12 years of age. Elevated copro- (p < 0.009), hexacarboxyl- (p < 0.01) and pentacarboxyl- (p < 0.001) porphyrin concentrations were significantly associated with AU but not with PDD-NOS. No differences were found between NT and AU in urinary Hg levels or in past Hg exposure as determined by fish consumption, number of dental amalgam fillings, or vaccines received. These findings identify disordered porphyrin metabolism as a salient characteristic of autism. Hg exposures were comparable between diagnostic groups, and a porphyrin pattern consistent with that seen in Hg-exposed adults was not apparent.

  6. Complexation of porphyrins with silver and zeolite nanoparticles

    NASA Astrophysics Data System (ADS)

    Gyulkhandanyan, Anna G.; Ghazaryan, Robert K.; Gasparyan, Vardan K.; Sargsyan, Hakob O.; Madoyan, Roza A.; Gyulkhandanyan, Aram G.; Paronyan, Marina H.; Stasheuski, Alexandr S.; Knyukshto, Valery N.; Dzhagarov, Boris M.; Gyulkhandanyan, Grigor V.

    2013-05-01

    It is known that nanoparticles of colloidal silver and zeolites due to the porosity have an extremely large specific surface, which is an order of magnitude increases their sorption capacity. Previously we synthesized a set of water-soluble cationic porphyrins and metalloporphyrins and in the laboratory in vitro had shown their high effectiveness against the various cancer cell lines, and against a variety of microorganisms. The aim of this work was to study of processes sorption/desorption of porphyrins on nanoparticles of silver and zeolites. The interaction of cationic porphyrins with silver nanoparticles of 20 nm diameter was studied in the visible spectrum, in the range 350-800 nm. Investigation of sorption dynamics of porphyrins in the silver nanoparticles using two porphyrins: a) meso-tetra (4-N-butyl pyridyl) porphyrin (TBut4PyP), b) Ag-TBut4PyP, as well as of photosensitizer Al-phthalocyanine was carried out. Analysis of the dynamics of change in the absorption spectra for porphyrins TBut4PyP, Ag-TBut4PyP, Zn-TBut4PyP and Zn-TOEt4PyP by adding of nanoparticles of colloidal silver and zeolites leads to the conclusions: 1. nanoparticles of colloidal silver and zeolites are promising adsorbents for cationic porphyrins (sorption of 55-60% and 90-95%, respectively); 2. sorbents stable long (at least 24 hours) keeps the cationic porphyrins; 3. on nanoparticles of colloidal silver and zeolites an anionic and neutral porphyrins not be adsorbed or adsorbed bad.

  7. Histological assessment of augmented jaw bone utilizing a new collagen barrier membrane compared to a standard barrier membrane to protect a granular bone substitute material.

    PubMed

    Friedmann, Anton; Strietzel, Frank Peter; Maretzki, Burghard; Pitaru, Sandu; Bernimoulin, Jean-Pierre

    2002-12-01

    Successful bone augmentation requires predictable space maintenance and adequate exclusion of those cells that lack osteogenetic potential from the defect area. Natural bone mineral is considered to be osteoconductive and is used as space maker in combination with membrane barrier techniques. The aim of this study was to compare qualitative histological results achieved by using deproteinized bovine bone mineral (DBBM) as a space maintainer and a new collagen barrier (Ossix, test group) vs. the same bone substitute and the standard e-PTFE membrane (Gore-Tex), control group). Twenty-eight patients were randomly assigned to the test or the control group. Seven months after augmentation procedures, biopsies were obtained at reentry and were analysed histomorphometrically. In all, 14 specimens of group I (test group, Ossix) and 13 specimens of group II (controls, PTFE-membranes) showed close qualitative similarity of their histologies. Histomorphometrically, total mineralized bone area was 42% +/- 18% in group I vs. 39% +/- 15% in group II. The unmineralized tissue area was 44% +/- 15% vs. 46% +/- 12% and the area of DBBM remnants 14% +/- 9% and 15% +/- 12%, respectively. The differences were statistically nonsignificant (Mann-Whitney test). The occurrence of barrier exposure did not interfere with the histological outcome either in the test or in the control group. The new collagen barrier combined with the DBBM provided qualitative bone regeneration comparable to the standard e-PTFE material combined with the same mineral.

  8. Effect of cholesterol and sugar on the penetration of glycodendrimeric phenylporphyrins into biomimetic models of retinoblastoma cells membranes.

    PubMed

    Makky, A; Michel, J P; Ballut, S; Kasselouri, A; Maillard, Ph; Rosilio, V

    2010-07-06

    Photodynamic therapy (PDT) is considered one efficient treatment against retinoblastoma. The specificity of a photosensitizer and its penetration into cancerous cells are crucial for achieving tumor necrosis. The selection of photosensitizers such as porphyrin derivatives by tumor cells thus depends to a large extent on their ability to interact with the biological membrane. In this work, we have studied by surface pressure measurements and fluorescence spectroscopy the interaction between three newly synthesized dendrimeric phenylporphyrins and monolayers or liposomes with increasing cholesterol content mimicking the retinoblastoma cell membrane. The morphology of phospholipid-cholesterol-porphyrin mixed monolayers was also analyzed by Brewster angle microscopy. The results showed that the increase in cholesterol content in the model membranes had almost no effect on the effective penetration of the drugs into the lipid layers. Conversely, the chemical structure of the glycodendrimeric phenylporphyrins and the presence of sugar moieties especially appeared to play a crucial role. Although the non-glycoconjugated phenylporphyrin penetrated to a greater extent than glycodendrimeric ones into the liposome membrane, this could be achieved at a high lipid/porphyrin ratio only. Glycodendrimeric porphyrins exhibited improved surface properties compared to the non-glycoconjugated derivative and could penetrate into lipid layers even at low lipid/porphyrin ratios and high surface pressures. Our work highlights the role in the passive diffusion of porphyrins into biomimetic cancer cell membranes, of complex interactions among the lipid molecules, the sugar moieties, and the hydrophobic macrocycle of the porphyrins.

  9. New water-soluble Mn-porphyrin with catalytic activity for superoxide dismutation and peroxynitrite decomposition.

    PubMed

    Asayama, Shoichiro; Nakajima, Takumi; Kawakami, Hiroyoshi

    2011-07-01

    We have synthesized a new water-soluble cationic Mn-porphyrin with catalytic activity for both superoxide dismutation and peroxynitrite decomposition. The resulting Mn-porphyrin also showed higher stability for reactive oxygen species such as hydrogen peroxide and lower cytotoxicity, when compared with a control normal Mn-porphyrin. Furthermore, the new porphyrin recovered the viability of lipopolysaccharide-stimulated macrophage RAW 264.7 cells but the control Mn-porphyrin did not.

  10. Molecular docking and dynamics simulations on the interaction of cationic porphyrin-anthraquinone hybrids with DNA G-quadruplexes.

    PubMed

    Arba, Muhammad; Kartasasmita, Rahmana E; Tjahjono, Daryono H

    2016-01-01

    A series of cationic porphyrin-anthraquinone hybrids bearing either pyridine, imidazole, or pyrazole rings at the meso-positions have been investigated for their interaction with DNA G-quadruplexes by employing molecular docking and molecular dynamics simulations. Three types of DNA G-quadruplexes were utilized, which comprise parallel, antiparallel, and mixed hybrid topologies. The porphyrin hybrids have a preference to bind with parallel and mixed hybrid structures compared to the antiparallel structure. This preference arises from the end stacking of porphyrin moiety following G-stem and loop binding of anthraquinone tail, which is not found in the antiparallel due to the presence of diagonal and lateral loops that crowd the G-quartet. The binding to the antiparallel, instead, occurred with poorer affinity through both the loop and wide groove. All sites of porphyrin binding were confirmed by 6 ns molecular dynamics simulation, as well as by the negative value of the total binding free energies that were calculated using the MMPBSA method. Free energy analysis shows that the favorable contribution came from the electrostatic term, which supposedly originated from the interaction of either cationic pyridinium, pyrazole, or imidazole groups and the anionic phosphate backbone, and also from the van der Waals energy, which primarily contributed through end stacking interaction.

  11. Water Dispersible and Biocompatible Porphyrin-Based Nanospheres for Biophotonics Applications: A Novel Surfactant and Polyelectrolyte-Based Fabrication Strategy for Modifying Hydrophobic Porphyrins.

    PubMed

    Sheng, Ning; Zong, Shenfei; Cao, Wei; Jiang, Jianzhuang; Wang, Zhuyuan; Cui, Yiping

    2015-09-09

    The hydrophobility of most porphyrin and porphyrin derivatives has limited their applications in medicine and biology. Herein, we developed a novel and general strategy for the design of porphyrin nanospheres with good biocompatibility and water dispersibility for biological applications using hydrophobic porphyrins. In order to display the generality of the method, we used two hydrophobic porphyrin isomers as starting material which have different structures confirmed by an X-ray technique. The porphyrin nanospheres were fabricated through two main steps. First, the uniform porphyrin nanospheres stabilized by surfactant were prepared by an interfacially driven microemulsion method, and then the layer-by-layer method was used for the synthesis of polyelectrolyte-coated porphyrin nanospheres to reduce the toxicity of the surfactant as well as improve the biocompatibility of the nanospheres. The newly fabricated porphyrin nanospheres were characterized by TEM techniques, the electronic absorption spectra, photoluminescence emission spectra, dynamic light scattering, and cytotoxicity examination. The resulting nanospheres demonstrated good biocompatibility, excellent water dispersibility and low toxicity. In order to show their application in biophotonics, these porphyrin nanospheres were successfully applied in targeted living cancer cell imaging. The results showed an effective method had been explored to prepare water dispersible and highly stable porphyrin nanomaterial for biophotonics applications using hydrophobic porphyrin. The approach we reported shows obvious flexibility because the surfactants and polyelectrolytes can be optionally selected in accordance with the characteristics of the hydrophobic material. This strategy will expand the applications of hydrophobic porphyrins owning excellent properties in medicine and biology.

  12. The Utility of High-Fidelity Simulation for Training Critical Care Fellows in the Management of Extracorporeal Membrane Oxygenation Emergencies: A Randomized Controlled Trial.

    PubMed

    Zakhary, Bishoy M; Kam, Lily M; Kaufman, Brian S; Felner, Kevin J

    2017-08-01

    Although extracorporeal membrane oxygenation volume has increased, proficiency in the technology requires extensive training. We compared traditional water-drill-based extracorporeal membrane oxygenation training with simulation-based extracorporeal membrane oxygenation training with the hypothesis that simulation-based training is superior. Randomized controlled trial. Academic medical center. Pulmonary/critical care fellows. Participants had a preintervention simulated extracorporeal membrane oxygenation emergency (Sim1-recirculation) then randomized into simulation and traditional groups. Each group participated in three teaching scenarios, via high-fidelity simulation or via water-drills. After 6 weeks and after 1 year, participants returned for two simulated extracorporeal membrane oxygenation emergencies (Sim2-pump failure and Sim3-access insufficiency). Sim2 was a case encountered during teaching, whereas Sim3 was novel. A critical action, necessary for resolution of each scenario, was preidentified for timing. Primary outcome was time required to perform critical actions. Twenty-one fellows participated in the study (simulation, 10; traditional, 11). Groups had similar scenario scores (p = 0.4) and times to critical action (p = 0.8) on Sim1. At 6 weeks, both groups had similar scenario scores on Sim2 (p = 0.5), but the simulation group scored higher on Sim3 (p = 0.03). Times to critical actions were shorter in the simulation group during Sim2 (127 vs 174 s, p = 0.004) and Sim3 (159 vs 300 s; p = 0.04). These findings persisted at 1 year. In novice critical care fellows, simulation-based extracorporeal membrane oxygenation training is superior to traditional training. Benefits transfer to novel scenarios and are maintained over the long term. Further studies evaluating the utility of simulation in other learner groups and for maintenance of proficiency are required.

  13. Utilization of composite membrane polyethyleneglycol-polystyrene-cellulose acetate from pineapple leaf fibers in lowering levels of methyl orange batik waste

    NASA Astrophysics Data System (ADS)

    Delsy, E. V. Y.; Irmanto; Kazanah, F. N.

    2017-02-01

    Pineapple leaves are agricultural waste from the pineapple that the fibers can be utilized as raw material in cellulose acetate membranes. First, made pineapple leaf fibers into pulp and then converted into cellulose acetate by acetylation process in four stages consisting of activation, acetylation, hydrolysis and purification. Cellulose acetate then used as the raw material to manufacture composite membrane with addition of polystyrene and poly (ethylene glycol) as porogen. Composite membrane is made using phase inversion method with dichloromethane-acetone as a solvent. The result of FTIR analysis (Fourier transform infra-red) showed that the absorption of the carbonyl group (C=O) is at 1643.10 cm-1 and acetyl group (C-O ) at 1227.01 cm-1, with a molecular weight of 8.05 x 104 g/mol and the contents (rate) of acetyl is 37.31%. PS-PEG-CA composite membrane had also been characterized by measuring the water flux values and its application to decrease methyl orange content (level) in batik waste. The results showed that the water flux value is of 25.62 L/(m2.hour), and the decrease percentage of methyl orange content in batik waste is 71.53%.

  14. Characterization of mesoscale coiled-coil peptide-porphyrin complexes.

    PubMed

    Pepe-Mooney, Brian J; Kokona, Bashkim; Fairman, Robert

    2011-12-12

    Photoelectronically conductive self-assembling peptide-porphyrin assemblies have great potential in their use as biomaterials, owing largely to their environmentally responsive properties. We have successfully designed a coiled-coil peptide that can self-assemble to form mesoscale filaments and serve as a scaffold for porphyrin interaction. In our earlier work, peptide-porphyrin-based biomaterials were formed at neutral pH, but the structures were irregular at the nano- to microscale size range, as judged by atomic force microscopy. We identified a pH in which mesoscale fibrils were formed, taking advantage of the types of porphyrin interactions that are present in well-characterized J-aggregates. We used UV-visible spectroscopy, circular dichroism spectropolarimetry, fluorescence spectroscopy, and atomic force microscopy to characterize these self-assembling biomaterials. We propose a new assembly paradigm that arises from a set of unique porphyrin-porphyrin and porphyrin-peptide interactions whose structure may be readily modulated by changes in pH or peptide concentration.

  15. The two-step mechanochemical synthesis of porphyrins.

    PubMed

    Shy, Hannah; Mackin, Paula; Orvieto, Andrea S; Gharbharan, Deepa; Peterson, Geneva R; Bampos, Nick; Hamilton, Tamara D

    2014-01-01

    Porphyrin synthesis under solvent-free conditions represents the "greening" of a traditional synthesis that normally requires large amounts of organic solvent, and has hindered the industrial-scale synthesis of this useful class of molecules. We have found that the four-fold acid-catalysed condensation of aldehyde and pyrrole to yield a tetra-substituted porphyrin is possible through mechanochemical techniques, without a solvent present. This represents one of the still-rare examples of carbon-carbon bond formation by mechanochemistry. Specifically, upon grinding equimolar amounts of pyrrole and benzaldehyde in the presence of an acid catalyst, cyclization takes place to give reduced porphyrin precursors (reversible), which upon oxidation form tetraphenylporphyrin (TPP). The approach has been found to be suitable for the synthesis of a variety of meso-tetrasubstituted porphyrins. Oxidation can occur either by using an oxidizing agent in solution, to give yields comparable to those published for traditional methods of porphyrin synthesis, or through mechanochemical means resulting in a two-step mechanochemical synthesis to give slightly lower yields that are still being optimized. We are also working on "green" methods of porphyrin isolation, including entrainment sublimation, which would hopefully further reduce the need for large amounts of organic solvent. These results hold promise for the development of mechanochemical synthetic protocols for porphyrins and related classes of compounds.

  16. Excitation energy migration processes in various multi-porphyrin assemblies.

    PubMed

    Yang, Jaesung; Kim, Dongho

    2012-08-13

    The electronic interactions and excitation energy transfer (EET) processes of a variety of multi-porphyrin arrays with linear, cyclic and box architectures have been explored. Directly meso-meso linked linear arrays (Z(N)) exhibit strong excitonic coupling with an exciton coherence length of approximately 6 porphyrin units, while fused linear arrays (T(N)) exhibit extensive π-conjugation over the whole array. The excitonic coherence length in directly linked cyclic porphyrin rings (CZ(N)) was determined to be approximately 2.7 porphyrin units by simultaneous analysis of fluorescence intensities and lifetimes at the single-molecule level. By performing transient absorption (TA) and TA anisotropy decay measurements, the EET rates in m-phenylene linked cyclic porphyrin wheels C12ZA and C24ZB were determined to be 4 and 36 ps(-1), respectively. With increasing the size of C(N)ZA, the EET efficiencies decrease owing to the structural distortions that produce considerable non-radiative decay pathways. Finally, the EET rates of self-assembled porphyrin boxes consisting of directly linked diporphyrins, B1A, B2A and B3A, are 48, 98 and 361 ps(-1), respectively. The EET rates of porphyrin boxes consisting of alkynylene-bridged diporphyrins, B2B and B4B, depend on the conformation of building blocks (planar or orthogonal) rather than the length of alkynylene linkers.

  17. Biosynthetic porphyrins and the origin of photosynthesis

    NASA Technical Reports Server (NTRS)

    Mauzerall, D.; Ley, A.; Mercer-Smith, J. A.

    1986-01-01

    Since the prebiotic atmosphere was anaerobic, if not reducing, a useful function of primordial photosynthesis would have been to photooxidize reduced substrates such as Fe(+2), S(-2) or reduced organic molecules and to emit hydrogen. Experiments have shown that the early biogenic pigments uroporphyrin and coproporphyrin do photooxidize organic compounds and emit hydrogen in the presence of a platinum catalyst. These experiments were carried out in dilute aqueous solution near neutral pH under anaerobic atmosphere, and quantum yields near 10-2 were obtained. Thus relevant prebiotic conditions were maintained. Rather then to further optimize conditions, attempts were made to replace the platinum catalyst by a more prebiotically suitable catalyst. Trials with an Fe4S4(SR)4 cluster, in analogy to the present hydrogenase and nitrogenase, were not successful. However, experiments using cobalt complexes to catalyze the formation of hydrogen are promising. In analogy with biological photosynthetic systems which group pigments, electron transfer molecules and enzymes in clusters for efficiency, it was found that binding the biogenic porphyrins to the polyvinyl alcohol used to support the platinum catalyst did increase the quantum yield of the reaction. It was also found that ultraviolet light can serve to photo-oxidize porphyrinogens to porphyrins under anaerobic conditions. Thus the formation of the colorless porphyriogens by the extraordinarily simple biosynthetic pathway would not be a problem because of the prevalence of UV light in the prebiotic, anoxic atmosphere.

  18. Spectroscopic identification of reactive porphyrin motions

    NASA Astrophysics Data System (ADS)

    Barabanschikov, Alexander; Demidov, Alexander; Kubo, Minoru; Champion, Paul M.; Sage, J. Timothy; Zhao, Jiyong; Sturhahn, Wolfgang; Alp, E. Ercan

    2011-07-01

    Nuclear resonance vibrational spectroscopy (NRVS) reveals the vibrational dynamics of a Mössbauer probe nucleus. Here, 57Fe NRVS measurements yield the complete spectrum of Fe vibrations in halide complexes of iron porphyrins. Iron porphine serves as a useful symmetric model for the more complex spectrum of asymmetric heme molecules that contribute to numerous essential biological processes. Quantitative comparison with the vibrational density of states (VDOS) predicted for the Fe atom by density functional theory calculations unambiguously identifies the correct sextet ground state in each case. These experimentally authenticated calculations then provide detailed normal mode descriptions for each observed vibration. All Fe-ligand vibrations are clearly identified despite the high symmetry of the Fe environment. Low frequency molecular distortions and acoustic lattice modes also contribute to the experimental signal. Correlation matrices compare vibrations between different molecules and yield a detailed picture of how heme vibrations evolve in response to (a) halide binding and (b) asymmetric placement of porphyrin side chains. The side chains strongly influence the energetics of heme doming motions that control Fe reactivity, which are easily observed in the experimental signal.

  19. Biosynthetic porphyrins and the origin of photosynthesis

    NASA Technical Reports Server (NTRS)

    Mauzerall, D.; Ley, A.; Mercer-Smith, J. A.

    1986-01-01

    Since the prebiotic atmosphere was anaerobic, if not reducing, a useful function of primordial photosynthesis would have been to photooxidize reduced substrates such as Fe(+2), S(-2) or reduced organic molecules and to emit hydrogen. Experiments have shown that the early biogenic pigments uroporphyrin and coproporphyrin do photooxidize organic compounds and emit hydrogen in the presence of a platinum catalyst. These experiments were carried out in dilute aqueous solution near neutral pH under anaerobic atmosphere, and quantum yields near 10-2 were obtained. Thus relevant prebiotic conditions were maintained. Rather then to further optimize conditions, attempts were made to replace the platinum catalyst by a more prebiotically suitable catalyst. Trials with an Fe4S4(SR)4 cluster, in analogy to the present hydrogenase and nitrogenase, were not successful. However, experiments using cobalt complexes to catalyze the formation of hydrogen are promising. In analogy with biological photosynthetic systems which group pigments, electron transfer molecules and enzymes in clusters for efficiency, it was found that binding the biogenic porphyrins to the polyvinyl alcohol used to support the platinum catalyst did increase the quantum yield of the reaction. It was also found that ultraviolet light can serve to photo-oxidize porphyrinogens to porphyrins under anaerobic conditions. Thus the formation of the colorless porphyriogens by the extraordinarily simple biosynthetic pathway would not be a problem because of the prevalence of UV light in the prebiotic, anoxic atmosphere.

  20. Porphyrin Interactions with Wild Type and Mutant Mouse Ferrochelatase

    SciTech Connect

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

    1999-05-19

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

  1. An optode sensor for Cu2+ with high selectivity based on porphyrin derivative appended with bipyridine.

    PubMed

    Luo, Hong-Yuan; Zhang, Xiao-Bing; Jiang, Jian-Hui; Li, Chun-Yan; Peng, Jing; Shen, Guo-Li; Yu, Ru-Qin

    2007-05-01

    A porphyrin derivative (fluorophore) appended with bipyridine (ionophore) has been applied for preparation of a Cu2+-sensitive optical chemical sensor, which is based on fluorescence quenching of porphyrin derivative entrapped in a poly(vinyl chloride) membrane by the energy transfer process. The sensor exhibits a linear response toward Cu2+ in the concentration range 2.0 x 10(-8) - 1.0 x 10(-5) M, with a working pH range from 6.0 to 8.0 and a high selectivity. The detection limit is 5 x 10(-9) M. The response time for Cu2+ is less than 5 min with concentrations lower than 5 x 10(-6) M. The optode can be regenerated using 0.3 M EDTA (pH 9) and acetate buffer solution. The effect of the composition of the sensor membrane was studied, and the experimental conditions were optimized. The sensor has been used for direct determination of Cu2+ in water samples with satisfied results.

  2. Three-component noncovalent assembly consisting of a central tetrakis-4-pyridyl porphyrin and two lateral gable-like bis-Zn porphyrins.

    PubMed

    Beyler, Maryline; Heitz, Valérie; Sauvage, Jean-Pierre; Ventura, Barbara; Flamigni, Lucia; Rissanen, Kari

    2009-09-07

    A pentaporphyrinic assembly was formed in one step, quantitatively, from a gable like zinc(II) bis-porphyrin and a free-base meso-tetrakis(4-pyridyl)porphyrin, because of the formation of four zinc-nitrogen coordination bonds. The X-ray crystal structure obtained shows a symmetrical structure, the free-base porphyrin being located at the center of a square formed by the four zinc atoms of the two zinc(II) bis-porphyrins. The two phenanthrolines connecting the zinc porphyrins are respectively above and below the plane of the central free-base porphyrin because of favorable CH-pi interactions between several porphyrinic assemblies within the crystal. Spectrophotometric and spectrofluorimetric titrations and studies reveal a high association constant for the porphyrinic assembly in the order of 10(14) M(-2). As expected, energy transfer from the zinc porphyrin component to the central free-base porphyrin quenches the fluorescence of the zinc porphyrin components whereas no sensitization of the emission of the free-base porphyrin was observed. Hypotheses on this unusual behavior are discussed.

  3. Second sphere control of spin state: Differential tuning of axial ligand bonds in ferric porphyrin complexes by hydrogen bonding.

    PubMed

    Mittra, Kaustuv; Sengupta, Kushal; Singha, Asmita; Bandyopadhyay, Sabyasachi; Chatterjee, Sudipta; Rana, Atanu; Samanta, Subhra; Dey, Abhishek

    2016-02-01

    An iron porphyrin with a pre-organized hydrogen bonding (H-Bonding) distal architecture is utilized to avoid the inherent loss of entropy associated with H-Bonding from solvent (water) and mimic the behavior of metallo-enzyme active sites attributed to H-Bonding interactions of active site with the 2nd sphere residues. Resonance Raman (rR) data on these iron porphyrin complexes indicate that H-Bonding to an axial ligand like hydroxide can result in both stronger or weaker Fe(III)-OH bond relative to iron porphyrin complexes. The 6-coordinate (6C) complexes bearing water derived axial ligands, trans to imidazole or thiolate axial ligand with H-Bonding stabilize a low spin (LS) ground state (GS) when a complex without H-Bonding stabilizes a high spin (HS) ground state. DFT calculations reproduce the trend in the experimental data and provide a mechanism of how H-Bonding can indeed lead to stronger metal ligand bonds when the axial ligand donates an H-Bond and lead to weaker metal ligand bonds when the axial ligand accepts an H-Bond. The experimental and computational results explain how a weak Fe(III)-OH bond (due to H-Bonding) can lead to the stabilization of low spin ground state in synthetic mimics and in enzymes containing iron porphyrin active sites. H-Bonding to a water ligand bound to a reduced ferrous active site can only strengthen the Fe(II)-OH2 bond and thus exclusion of water and hydrophilic residues from distal sites of O2 binding/activating heme proteins is necessary to avoid inhibition of O2 binding by water. These results help demonstrate the predominant role played by H-Bonding and subtle changes in its orientation in determining the geometric and electronic structure of iron porphyrin based active sites in nature. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. The Synthesis and Photophysical Characterization of Porphyrin Photoactive Materials for Use as Sensitizers in Organic Photovoltaics and Photodynamic Therapy

    NASA Astrophysics Data System (ADS)

    Marin, Dawn Marie

    Solar energy conversion and photodynamic therapy (PDT) are very different applications. However, both utilize very similar photoactive molecules called porphyrins. Porphyrins are structural analogs of chlorophyll and also function as prosthetic groups in some biological enzymes. Understanding the structure/function relationship of these molecules is crucial for enhancing the energy generation efficiency of molecular solar cells and improving chemotherapeutic activity in PDT. In this dissertation, two approaches were applied with the goal of increasing the efficiency of molecular semiconductors for these applications: the heavy atom effect and donor-acceptor molecules. We enhanced the efficiency of triplet excited state formation and singlet oxygen generation for porphyrin sensitizers using the heavy atom effect. The heavy atom effect induces spin-orbit coupling to promote intersystem crossing into the triplet state. In this study, a carbomethoxyphenyl substituent was replaced with either a bromophenyl or an iodophenyl substituent on 5,10,15,20-tetrakis(4-carbomethoxyphenyl)porphyrin. The longer lifetimes obtained from the increase in the triplet excited state allow for longer exciton diffusion lengths and lower recombination rates in photovoltaics. Also, the enhanced intersystem crossing is beneficial for photodynamic therapy because it increases singlet oxygen generation, which destroys tumor cells. Optimizing photovoltaic performance and PDT efficacy can also be accomplished with donor-acceptor molecules because they have extended electronic pi bond delocalization across the molecule, which causes the molecule to absorb longer wavelengths of light. Donor-acceptor molecules should produce photovoltaic devices that absorb more of the solar spectrum and produce sensitizers that absorb wavelengths of light that can penetrate through tissues. Donor-acceptor molecules were synthesized using 5,15-bis(4-carbomethoxyphenyl)porphyrin as the acceptor and thiazolo[5,4-d

  5. [Advantages of culture models utilizing substrata made of TOSHI (tissue/organ sections for histopathology) or collagen vitrigel membrane and their application concept for drug development researches].

    PubMed

    Takezawa, Toshiaki; Takeuchi, Tomoyo; Yanagihara, Kana; Nakazawa, Yukiko; Nitani, Aya; Terada, Satoshi; Ochiya, Takahiro; Ueno, Koichi

    2008-01-01

    To create new in vitro culture models for extrapolating the cell response in vivo, we attempted to devise culture substrata of anchorage-dependent cells. The first substratum, tissue/organ sections for histopathology(TOSHI)-substratum was found to conserve both tissue composition and microarchitecture in an in vivo environment. Collagen vitrigel membrane, the second substratum investigated, possesses excellent strength and protein permeability. Both substrata were developed and utilized for the culture of various anchorage-dependent cells. TOSHI-substratum prepared from regenerative mouse livers after carbon tetrachloride intoxication efficiently induced the differentiation of mouse embryonic stem cells into hepatocyte-like cells. Also, the time-course cell behavior of two different cell lines on various TOSHI-substrata prepared from rat mature organs was successfully converted into a three-dimensional graph chart, i.e. a mathematical model. These data suggest that the analysis of interactions between different cell types and various TOSHI-substrata will play an important role for a novel approach to study both cellomics and histomics. Meanwhile, the collagen vitrigel membrane is easy to handle by forceps, resulting in double surface-culture of different cell types by the manipulation of two-dimensional cultures. In the crosstalk model between PC-12 pheochromocytoma cells and L929 fibroblasts, nerve growth factor secreted from L929 cells permeated the collagen vitrigel membrane and induced neurite outgrowth of PC-12 cells via a paracrine effect. Futhermore, the function of rat primary hepatocytes was well maintained on the collagen vitrigel membrane. These data suggest that the collagen vitrigel membrane-substratum has many advantages for the reconstruction of culture models.

  6. Utilization of Electrically Reduced Neutral Red by Actinobacillus succinogenes: Physiological Function of Neutral Red in Membrane-Driven Fumarate Reduction and Energy Conservation

    PubMed Central

    Park, D. H.; Zeikus, J. G.

    1999-01-01

    Neutral red (NR) functioned as an electronophore or electron channel enabling either cells or membranes purified from Actinobacillus succinogenes to drive electron transfer and proton translocation by coupling fumarate reduction to succinate production. Electrically reduced NR, unlike methyl or benzyl viologen, bound to cell membranes, was not toxic, and chemically reduced NAD. The cell membrane of A. succinogenes contained high levels of benzyl viologen-linked hydrogenase (12.2 U), fumarate reductase (13.1 U), and diaphorase (109.7 U) activities. Fumarate reductase (24.5 U) displayed the highest activity with NR as the electron carrier, whereas hydrogenase (1.1 U) and diaphorase (0.8 U) did not. Proton translocation by whole cells was dependent on either electrically reduced NR or H2 as the electron donor and on the fumarate concentration. During the growth of Actinobacillus on glucose plus electrically reduced NR in an electrochemical bioreactor system versus on glucose alone, electrically reduced NR enhanced glucose consumption, growth, and succinate production by about 20% while it decreased acetate production by about 50%. The rate of fumarate reduction to succinate by purified membranes was twofold higher with electrically reduced NR than with hydrogen as the electron donor. The addition of 2-(n-heptyl)-4-hydroxyquinoline N-oxide to whole cells or purified membranes inhibited succinate production from H2 plus fumarate but not from electrically reduced NR plus fumarate. Thus, NR appears to replace the function of menaquinone in the fumarate reductase complex, and it enables A. succinogenes to utilize electricity as a significant source of metabolic reducing power. PMID:10198002

  7. Functional, photochemically active, and chemically asymmetric membranes by interfacial polymerization of derivatized multifunctional prepolymers

    DOEpatents

    Lonsdale, Harold K.; Wamser, Carl C.

    1990-01-01

    The preparation of a novel class of thin film membranes by interfacial polymerization is disclosed, said membranes incorporating as part of their polymeric structure the functionality of monomeric or oligomeric precursors. Specific embodiments include porphyrin and phthalocyanine derivatives that are photochemically or electrochemically active, as well as chemically asymmetric membranes.

  8. Functional, photochemically active, and chemically asymmetric membranes by interfacial polymerization of derivatized multifunctional prepolymers

    DOEpatents

    Lonsdale, H.K.; Wamser, C.C.

    1990-04-17

    The preparation of a novel class of thin film membranes by interfacial polymerization is disclosed, said membranes incorporating as part of their polymeric structure the functionality of monomeric or oligomeric precursors. Specific embodiments include porphyrin and phthalocyanine derivatives that are photochemically or electrochemically active, as well as chemically asymmetric membranes.

  9. FadD Is Required for Utilization of Endogenous Fatty Acids Released from Membrane Lipids ▿ †

    PubMed Central

    Pech-Canul, Ángel; Nogales, Joaquina; Miranda-Molina, Alfonso; Álvarez, Laura; Geiger, Otto; Soto, María José; López-Lara, Isabel M.

    2011-01-01

    FadD is an acyl coenzyme A (CoA) synthetase responsible for the activation of exogenous long-chain fatty acids (LCFA) into acyl-CoAs. Mutation of fadD in the symbiotic nitrogen-fixing bacterium Sinorhizobium meliloti promotes swarming motility and leads to defects in nodulation of alfalfa plants. In this study, we found that S. meliloti fadD mutants accumulated a mixture of free fatty acids during the stationary phase of growth. The composition of the free fatty acid pool and the results obtained after specific labeling of esterified fatty acids with a Δ5-desaturase (Δ5-Des) were in agreement with membrane phospholipids being the origin of the released fatty acids. Escherichia coli fadD mutants also accumulated free fatty acids released from membrane lipids in the stationary phase. This phenomenon did not occur in a mutant of E. coli with a deficient FadL fatty acid transporter, suggesting that the accumulation of fatty acids in fadD mutants occurs inside the cell. Our results indicate that, besides the activation of exogenous LCFA, in bacteria FadD plays a major role in the activation of endogenous fatty acids released from membrane lipids. Furthermore, expression analysis performed with S. meliloti revealed that a functional FadD is required for the upregulation of genes involved in fatty acid degradation and suggested that in the wild-type strain, the fatty acids released from membrane lipids are degraded by β-oxidation in the stationary phase of growth. PMID:21926226

  10. Enhanced UV-visible photodetection characteristics of a flexible Si membrane-ZnO heterojunction utilizing piezo-phototronic effect

    NASA Astrophysics Data System (ADS)

    Sarkar, Arijit; Katiyar, Ajit K.; Mukherjee, Subhrajit; Ray, Samit K.

    2017-04-01

    We report the characteristics of an n-ZnO/p-Si membrane heterojunction flexible photodetector sensitive to UV and visible illumination. A piezo-phototronic effect has been observed for the deposited ZnO thin films on flexible silicon membranes. Si membranes as low as ~3.0 µm thick have been fabricated by the alkaline etching of Si wafers followed by ZnO deposition using RF sputtering for realizing the heterostructure. A peak responsivity of 0.20 AW-1 with a detectivity of 4.8  ×  1011 cm Hz1/2 W-1 is found at ~490 nm for zero bias. Strain induced piezo-potential developed in ZnO thin films is found to modulate the transport property of the photo generated carriers, resulting in the enhanced performance of the device. With a gradual increase in the external tensile stress, the photocurrent increases by 22%. The accompanying COMSOL analysis displays the piezopotential distribution developed in ZnO films on application of an external stress to the heterojunction, which is in close agreement with the experimental data.

  11. Fabrication of enzyme reactor utilizing magnetic porous polymer membrane for screening D-Amino acid oxidase inhibitors.

    PubMed

    Jiang, Jun Fang; Qiao, Juan; Mu, Xiao Yu; Moon, Myeong Hee; Qi, Li

    2017-04-01

    In this work, a unique D-amino acid oxidase reactor for enhanced enzymolysis efficiency is presented. A kind of magnetic polymer matrices, composed of iron oxide nanoparticles and porous polymer membrane (poly styrene-co-maleic anhydride), was prepared. With covalent bonding D-Amino acid oxidase on the surface of the matrices and characterization of scanning electron microscope and vibrating sample magnetometer, it demonstrated that the membrane enzyme reactor was successfully constructed. The enzymolysis efficiency of the enzyme reactor was evaluated and the apparent Michaelis-Menten constants of D-Amino acid oxidase were determined (Km was 1.10mM, Vmax was 23.8mMmin(-1)) by a chiral ligand exchange capillary electrophoresis protocol with methionine as the substrate. The results indicated that the enzyme reactor could exhibit good stability and excellent reusability. Importantly, because the enzyme and the substrate could be confined into the pores of the matrices, the enzyme reactor displayed the improved enzymolysis efficiency due to the confinement effect. Further, the prepared enzyme reactor was applied for D-Amino acid oxidase inhibitors screening. It has displayed that the proposed protocol could pave a new way for fabrication of novel porous polymer membrane based enzyme reactors to screen enzyme inhibitors. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Challenging Density Functional Theory Calculations with Hemes and Porphyrins

    PubMed Central

    de Visser, Sam P.; Stillman, Martin J.

    2016-01-01

    In this paper we review recent advances in computational chemistry and specifically focus on the chemical description of heme proteins and synthetic porphyrins that act as both mimics of natural processes and technological uses. These are challenging biochemical systems involved in electron transfer as well as biocatalysis processes. In recent years computational tools have improved considerably and now can reproduce experimental spectroscopic and reactivity studies within a reasonable error margin (several kcal·mol−1). This paper gives recent examples from our groups, where we investigated heme and synthetic metal-porphyrin systems. The four case studies highlight how computational modelling can correctly reproduce experimental product distributions, predicted reactivity trends and guide interpretation of electronic structures of complex systems. The case studies focus on the calculations of a variety of spectroscopic features of porphyrins and show how computational modelling gives important insight that explains the experimental spectra and can lead to the design of porphyrins with tuned properties. PMID:27070578

  13. Studies on porphyrin photoproducts in solution, cells, and tumor tissue

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten; Schneckenburger, Herbert; Rueck, Angelika C.; Koenig, Roland

    1994-07-01

    Light excitation of photosensitizing porphyrins leads to cytotoxic reactions. In addition, photobleaching and photoproduct formation occur indicating photosensitizer destruction. Photoproducts from hematoporphyrin (HP) fluoresce in aqueous solution at 642 nm, whereas photoproducts from protoporphyrin (PP) in hydrophobic environment emit around 670 nm and exhibit pronounced absorption at 665 nm. Photoproduct formation depends on singlet oxygen. The photoproducts exhibit faster fluorescence decay kinetics compared with nonirradiated porphyrins, as shown by time-grated spectroscopy and fluorescence decay measurements. Photoproduct fluorescence was observed during light exposure of cells and of tumor-bearing, nude mice, following administration of Hematoporphyrin Derivative (HpD), tetramethyl-HP, and PP. Photoconversion was also detected with naturally-occurring porphyrins (PP-producing bacteria) and ALA-simulated biosynthesis of PP in tumor tissue and in skin lesions of patients (psoriasis, mycosis fungoides). The efficiency of PDT with porphyrin photoproducts was found to be low in spite of the strong electronic transitions in the red spectral region.

  14. Challenging Density Functional Theory Calculations with Hemes and Porphyrins.

    PubMed

    de Visser, Sam P; Stillman, Martin J

    2016-04-07

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

  15. Discrete cyclic porphyrin arrays as artificial light-harvesting antenna.

    PubMed

    Aratani, Naoki; Kim, Dongho; Osuka, Atsuhiro

    2009-12-21

    The importance of photosynthesis has driven researchers to seek ways to mimic its fundamental features in simplified systems. The absorption of a photon by light-harvesting (antenna) complexes made up of a large number of protein-embedded pigments initiates photosynthesis. Subsequently the many pigments within the antenna system shuttle that photon via an efficient excitation energy transfer (EET) until it encounters a reaction center. Since the 1995 discovery of the circularly arranged chromophoric assemblies in the crystal structure of light-harvesting antenna complex LH2 of purple bacteria Rps. Acidophila, many designs of light-harvesting antenna systems have focused on cyclic porphyrin wheels that allow for efficient EET. In this Account, we review recent research in our laboratories in the synthesis of covalently and noncovalently linked discrete cyclic porphyrin arrays as models of the photosynthetic light-harvesting antenna complexes. On the basis of the silver(I)-promoted oxidative coupling strategy, we have prepared a series of extremely long yet discrete meso-meso-linked porphyrin arrays and covalently linked large porphyrin rings. We examined the photophysical properties of these molecules using steady-state absorption, fluorescence, fluorescence lifetime, fluorescence anisotropy decay, and transient absorption measurements. Both the pump-power dependence on the femtosecond transient absorption and the transient absorption anisotropy decay profiles are directly related to the EET processes within the porphyrin rings. Within these structures, the exciton-exciton annihilation time and the polarization anisotropy rise time are well-described in terms of the Forster-type incoherent energy hopping model. In noncoordinating solvents such as CHCl(3), meso-pyridine-appended zinc(II) porphyrins and their meso-meso-linked dimers spontaneously assemble to form tetrameric porphyrin squares and porphyrin boxes, respectively. In the latter case, we have demonstrated

  16. meso-meso linked porphyrin-[26]hexaphyrin-porphyrin hybrid arrays and their triply linked tapes exhibiting strong absorption bands in the NIR region.

    PubMed

    Mori, Hirotaka; Tanaka, Takayuki; Lee, Sangsu; Lim, Jong Min; Kim, Dongho; Osuka, Atsuhiro

    2015-02-11

    We describe the synthesis and characterization of directly meso-meso linked porphyrin-[26]hexaphyrin-porphyrin hybrid oligomers and their triply linked (completely fused) hybrid tapes. meso-meso Linked Ni(II) porphyrin-[26]hexaphyrin-Ni(II) porphyrin trimers were prepared by methanesulfonic acid-catalyzed cross-condensation of meso-formyl Ni(II) porphyrins with a 5,10-diaryltripyrrane followed by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The Ni(II) porphyrin moieties were converted to Zn(II) porphyrins via an indirect route involving reduction of the [26]hexaphyrin to its 28π congener, acid-induced denickelation, oxidation of the [28]hexaphyrin, and finally Zn(II) ion insertion. Over the course of these transformations, porphyrin-[28]hexaphyrin-porphyrin trimers have been revealed to take on a Möbius aromatic twisted structure for the [28]hexaphyrin segment. Oxidation of meso-meso linked hybrid trimer bearing 5,15-diaryl Zn(II) porphyrins with DDQ/Sc(OTf)3 under mild conditions resulted in meso-meso coupling oligomerization, affording the corresponding dimeric (hexamer), trimeric (nonamer), and tetrameric (dodecamer) oligomers. On the other hand, oxidation of a meso-meso linked hybrid trimer bearing 5,10,15-triaryl Zn(II) porphyrin terminals with DDQ/Sc(OTf)3 under harsher conditions afforded a meso-meso, β-β, β-β triply linked hybrid porphyrin tape, which displays a sharp and intense absorption band at 1912 nm. Comparison of this extremely red-shifted absorption band with those of Zn(II) porphyrin tapes suggests that the bathochromic-shifting capability of a [26]hexaphyrin unit is large, almost equivalent to that of four individual Zn(II) porphyrin units. As demonstrated, the fusion of porphyrins to [26]hexaphyrin offers an efficient means to expand their conjugation networks, significantly expanding the capabilities attainable for these chromophores.

  17. Direct-patterning of porphyrin dot arrays and lines using electrohydrodynamic jet printing.

    PubMed

    Song, Chi Ho; Back, Sung Yul; Yu, Sung Il; Lee, Hyoung Jin; Kim, Beom Soo; Yang, Nam Yeol; Jeong, Soo Hoa; Ahn, Heejoon

    2012-01-01

    In this research, we have fabricated micron-sized patterns of porphyrins on silicon substrates using an electrohydrodynamic (EHD) jet printing technique. Optical and fluorescence microscopies have been used to examine the shape and fluorescence property of porphyrin patterns. The morphology of the porphyrin patterns printed with variously formulated porphyrin inks and the effects of applied voltage, working distance, and substrate properties on the morphology of patterns were investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). We have also demonstrated the acid-vapor sensing capability of the porphyrins by exposing the porphyrin patterns on Si substrates to nitric acid vapor.

  18. Novel Strategy Utilizing Extracellular Cysteine-Rich Domain of Membrane Receptor for Constructing d-Peptide Mediated Targeted Drug Delivery Systems: A Case Study on Fn14.

    PubMed

    Li, Zhuoxuan; Xie, Jing; Peng, Shan; Liu, Sha; Wang, Ying; Lu, Weiyue; Shen, Jie; Li, Chong

    2017-08-16

    The development of proteolysis-resistant d-peptide ligands for targeted drug/gene delivery has been greatly limited, due to the challenge that lies in the chemical synthesis of membrane receptors without altering their structures. In the present research, a novel strategy utilizing self-stabilized extracellular CRD of the membrane receptor was developed to construct d-peptide ligands and their mediated targeted drug delivery systems. Fn14, a cell surface receptor overexpressed in many cancers including pancreatic and triple-negative breast cancers, was selected as the model receptor. Fn14 CRD was synthesized and folded, and used to screen Fn14 binding peptides using phage display (l-peptide) and mirror-image phage display (d-peptide) techniques, respectively. The d-peptide ligand successfully mediated targeted drug delivery to Fn14 positive tumor cells. In addition, the d-peptide possessed better target-binding affinity, stromal barrier permeability, and tumor targeting ability in vivo when conjugated with liposomes. More importantly, d-peptide mediated liposomal paclitaxel delivery significantly inhibited pancreatic tumor growth in a subcutaneous xenograft model and drastically prolonged survival in a lung metastasis of breast cancer mouse model. This study demonstrated that mirror-image phage display based on the CRD of membrane receptor can be a promising strategy to advance active targeted drug delivery via biostable d-peptides.

  19. Identification of an iron-regulated outer membrane protein of Neisseria meningitidis involved in the utilization of hemoglobin complexed to haptoglobin.

    PubMed Central

    Lewis, L A; Dyer, D W

    1995-01-01

    Hemoglobin complexed to the plasma protein haptoglobin can be used by Neisseria meningitidis as a source of iron to support growth in vitro. An N meningitidis mutant, DNM2E4, was generated by insertion of the mini-Tn3erm transposon into the gene coding for an 85-kDa iron-regulated outer membrane protein. Membrane proteins prepared from DNM2E4 were identical to those of the wild-type strain except that the 85-kDa protein was not produced. This mutant was unable to use hemoglobin-haptoglobin complexes as an iron source to support growth and was also impaired in the utilization of free hemoglobin. The mutant failed to bind free hemoglobin, hemoglobin-haptoglobin complexes, or apo-haptoglobin in a solid-phase dot blot assay. The 85-kDa protein was affinity purified when hemoglobin-haptoglobin complexes were used as a ligand but was not purified when free hemoglobin was used. We hypothesize that the 85-kDa iron-regulated protein is the hemoglobin-haptoglobin receptor and designate this protein Hpu (for hemoglobin-haptoglobin utilization). PMID:7868605

  20. A conceptual demonstration of freeze desalination-membrane distillation (FD-MD) hybrid desalination process utilizing liquefied natural gas (LNG) cold energy.

    PubMed

    Wang, Peng; Chung, Tai-Shung

    2012-09-01

    The severe global water scarcity and record-high fossil oil price have greatly stimulated the research interests on new desalination technologies which can be driven by renewable energy or waste energy. In this study, a hybrid desalination process comprising freeze desalination and membrane distillation (FD-MD) processes was developed and explored in an attempt to utilize the waste cold energy released from re-gasification of liquefied natural gas (LNG). The concept of this technology was demonstrated using indirect-contact freeze desalination (ICFD) and direct-contact membrane distillation (DCMD) configurations. By optimizing the ICFD operation parameters, namely, the usage of nucleate seeds, operation duration and feed concentration, high quality drinkable water with a low salinity ∼0.144 g/L was produced in the ICFD process. At the same time, using the optimized hollow fiber module length and packing density in the DCMD process, ultra pure water with a low salinity of 0.062 g/L was attained at a condition of high energy efficiency (EE). Overall, by combining FD and MD processes and adopting the optimized operation parameters, the hybrid FD-MD system has been successfully demonstrated. A high total water recovery of 71.5% was achieved, and the water quality obtained met the standard for drinkable water. In addition, with results from specific energy calculation, it was proven that the hybrid process is an energy-saving process and utilization of LNG cold energy could greatly reduce the total energy consumption.

  1. Crystal fields of porphyrins and phthalocyanines

    NASA Astrophysics Data System (ADS)

    Johnson, P. S.; Boukahil, I.; Himpsel, F. J.; Kennedy, C.; Jersett, N.; Cook, P. L.; Garcia-Lastra, J. M.

    2014-03-01

    Polarization-dependent X-ray absorption spectroscopy at the N 1s and metal 2p edges is combined with density functional and atomic multiplet calculations to determine the crystal field parameters 10Dq, Ds, and Dt of transition metal (Mn, Fe, Co, Ni) phthalocyanines and octaethylporphyrins. Octaethyl porphyrins are observed to lie flat on Si with native oxide, while phthalocyanines lie on edge. Strong polarization dependence is found at all edges, which facilitates a unique determination of the crystal field parameters. Crystal field values from PBE density functional calculations provide helpful starting values, which are refined by fitting atomic multiplet calculations to the data. Since the crystal field affects electron-hole separation in solar cells, the systematic set of crystal field parameters obtained here can be useful for optimizing dyes for solar cells.

  2. Synthesis and Applications of New Water-Soluble Porphyrins and Explorations of Synthetic Routes to Quadrone

    NASA Astrophysics Data System (ADS)

    Jacobsen, John Lewis

    Porphyrins are attractive building blocks for self-assembled functional nanomaterials because they can be modified with a wide range of substituents and they possess diverse photophysical and chemical properties that are potentially useful in applications such as solar energy conversion, molecular electronics, catalysis and sensors. Recently, ionic self-assembly of oppositely-charged porphyrin tectons has been shown to produce well-defined structures such as nanotubes and nanofiber bundles. The synthesis of a novel cationic porphyrin tecton, tin 5,10,15,20-tetrakis(4-piperidyl)porphyrin is described. This porphyrin can be self-assembled with porphyrins such as 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin that only ionize under neutral or basic conditions. The nanostructures and metalized nanocomposites obtained from the self-assembly reactions are characterized using electron microscopy and spectroscopic techniques. In addition the synthesis and characterization of zinc and tin complexes of T(N-EtOH-Py)P are described and the ionic self-assembly reactions of these compounds to produce cooperative binary ionic solids are discussed. Quadrone's complex tetracyclic skeletal structure has allowed it to serve as an excellent showcase molecule for total synthesis. Three distinct routes were developed and tested in hopes of achieving an elusive substituted 10-hydroxy-dec-8-ynoic acid. Route I explored the limits of 1,4-conjugate addition. We were able to reproduce work demonstrating the remarkable selectivity that organomanganese reagents show for 1,4-addition even when the beta-carbon bears germinal-dimethyl substitution. Unfortunately, the propargylic manganese reagent needed for addition could not be synthesized despite using a diverse set of conditions and reagents. The second route demonstrated that an 11-membered acetylenic lactone could be transesterified into the corresponding methyl ester. This methyl ester resisted hydrolysis in the most forcing conditions

  3. Selective cell death by water-soluble Fe-porphyrins with superoxide dismutase (SOD) activity.

    PubMed

    Kasugai, Nobuyoshi; Murase, Toru; Ohse, Toshiyuki; Nagaoka, Shoji; Kawakami, Hiroyoshi; Kubota, Sunao

    2002-08-15

    We investigated the effect on cell death of reactive oxygen species induced by [[5,10 (or 5,15)-bis(N-methyl-4-pyridyl)-15,20 (or 10,20) diphenyl]porphinato]iron (cis-FeMPy(2)P(2)P or trans-FeMPy(2)P(2)P) with SOD activity. The SOD activities of the cis-FeMPy(2)P(2)P and trans-FeMPy(2)P(2)P were measured using stopped-flow kinetic analysis. The cell viability of four cell lines treated with cis-Fe-porphyrin, trans-Fe-porphyrin, mitomycin c (MMC), or cisplatin was estimated by the alamar blue exclusion assay of the modified MTT method. The amount of cis-FeMPy(2)P(2)P and trans-FeMPy(2)P(2)P in the Walker 256 cultured for 24 h was 4.0 and 2.6 fmolcell(-1), respectively, indicating that the plasma membrane permeability of the Fe-porphyrins depended on their structure. Cis-FeMPy(2)P(2)P selectively killed Walker 256 and H-4-II-E as cancer cells but not FR and BRL-3A as normal cells and showed a significant cytotoxicity for the cancer cells compared with trans-FeMPy(2)P(2)P, MMC and cisplatin. We believe that cis-FeMPy(2)P(2)P as an SOD mimic converts intracellular O(2)(*-) to H(2)O(2) and that H(2)O(2) or *OH causes DNA damage and induces cell death. This result suggests that for the SOD mimic, O(2)(*-) may be useful as a target molecule to induce selective cell death between cancer and normal cells and that a metalloporphyrin having SOD activity is a new class of anticancer agents.

  4. The Harderian gland, its secretory duct and porphyrin content in the mongolian gerbil (Meriones unguiculatus).

    PubMed Central

    Johnston, H S; McGadey, J; Thompson, G G; Moore, M R; Payne, A P

    1983-01-01

    The Harderian gland, its secretory duct and porphyrin content were examined in the mongolian gerbil (Meriones unguiculatus). The gland consisted of tubules lined by a single layer of epithelial cells and a myoepithelial network. The tubule cells were often binucleate and possessed lipid vacuoles in the apical half of the cell, a corona of granular endoplasmic reticulum surrounding the nucleus, and cytoplasmic 'slashes'. The latter are probably derived from dense membranous couplets and may be precursors of the lipid vacuoles. Holocrine and merocrine secretion was observed. Interstitial cells included plasma cells, mast cells and (predominantly) melanocytes which render the gland black. The gland was surrounded by a collagen capsule and an outer layer of highly attenuated (possibly endothelioid) cells. Within the gland, the secretory duct was lined by a single layer of normal tubule cells. Outside the gland, the duct enlarged to form an ampulla, from which clefts led off to deep crypts. The ampulla and clefts were lined by cells with small dense apical granules and stubby microvilli; some possessed lipid vacuoles. The crypts were lined by serous cells with active Golgi regions. At the duct opening, ampullary cells became squamous and goblet cells occurred. Geometric crystalloid deposits (with a layered structure of 7.6 nm periodicity) occurred at cleft-crypt junctions. Islets of extra-glandular ductal tissue were occasionally found within the gland. Porphyrins were detectable both by chemical assay and fluorescence microscopy. There was a trend for female glands to have a higher content than males. Solid intraluminal accretions of porphyrin and/or lipid were present. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 PMID:6654750

  5. DNA interaction and photocleavage properties of porphyrins containing cationic substituents at the peripheral position.

    PubMed

    Mettath, S; Munson, B R; Pandey, R K

    1999-01-01

    A series of mono- and disubstituted cationic porphyrins (1-8) were synthesized and investigated for their ability to bind and cleave DNA in the presence of light. In these porphyrins, the cationic substituents were introduced at various peripheral positions, i.e., the non-meso positions of the porphyrin system. The modes of binding of these porphyrins to DNA were investigated by UV-vis spectroscopy, circular dichroism, and an unwinding assay. The intrinsic binding constants Kb of these porphyrins to calf thymus DNA was found to be in the range 10(4)-10(5) M-1. Two of the zinc(II) complexes of non-meso-substituted cationic porphyrins (5 and 8) were found to bind to DNA via intercalation, which is in contrast to the previously reported outside-binding mode for the Zn(II) complexes of meso-substituted cationic porphyrins. Except for monocationic porphyrin 1 and Ni(II) dicationic porphyrin 6, all the other porphyrins were found to be efficient photocleavers of DNA. The DNA photocleavage characteristics of this series of cationic porphyrins were found to depend on the structural characteristics of the poprhyrins such as (a) length of the side chain of the cationic substituents (2 vs 4), (b) the position of the side chain on the porphyrin ring (4 vs 7), and (c) the presence of the chelating metal in 3, 5, and 8 as compared to the nonmetallo porphyrins 2, 4, and 7, respectively.

  6. Development and characterization of porphyrin chromophores for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Splan, Kathryn Elizabeth

    Increased public awareness of the Earth's depleting oil reserves and the adverse effect of greenhouse gasses are driving the development of alternative energy resources, including solar power. While the supply of energy from the Sun to the Earth is enormous, exploitation of this formidable natural resource remains a scientific challenge. Considerable efforts in fundamental research are still necessary for solar power to become a reality. The interesting optical and electronic properties and synthetic versatility of porphyrin chromophores constitute a valuable tool for further understanding the processes involved in efficient light-harvesting and current generation. This thesis describes the design and characterization of several porphyrin-based systems for solar energy conversion studies. Chapter 2 reports on the synthesis, photophysical characterization, and energy transfer (EnT) applications of a series of porphyrin dimers based on Re(l) pyridyl ligation that, despite incorporation of rhenium into the assembly, remain significantly fluorescent. In the context of solar energy conversion, the dimers allow for the systematic study of factors that modulate interpigment EnT. Chapter 3 presents a scheme for porphyrin-based multilayer sensitization of dye-sensitized solar cells (DSSCs). Porous, chromophoric, thin films based on tetrameric porphyrin squares were fabricated via layer-by-layer zirconium phosphonate chemistry, and their photoelectrochemical responses were evaluated. The studies reveal an additional, cathodic-current generating mechanism, which represents a parasitic process in the context of DSSCs. In Chapters 4 and 5, second generation porphyrin compounds are developed in efforts of optimizing the multilayer response. Porphyrin thin films are presented in which both excited state lifetime and mobility are enhanced. The photoelectrochemical response of the films in the context of DSSCs is evaluated. In chapter 6 a strategy is described in which the narrow

  7. Carbon dioxide capture and nutrients removal utilizing treated sewage by concentrated microalgae cultivation in a membrane photobioreactor.

    PubMed

    Honda, Ryo; Boonnorat, Jarungwit; Chiemchaisri, Chart; Chiemchaisri, Wilai; Yamamoto, Kazuo

    2012-12-01

    A highly efficient microalgae cultivation process was developed for carbon dioxide capture using nutrients from treated sewage. A submerged-membrane filtration system was installed in a photobioreactor to achieve high nutrient loading and to maintain a high concentration and production of microalgae. Chlorella vulgaris, Botryococcus braunii and Spirulina platensis were continuously cultivated with simulated treated sewage and 1%-CO(2) gas. The optimum hydraulic retention time (HRT) and solids retention time (SRT) were explored to achieve the maximum CO(2) capture rate, nutrient removal rate and microalgae biomass productivity. The carbon dioxide capture rate and volumetric microalgae productivity were high when the reactor was operated under 1-day (HRT) and 18-days (SRT) conditions. The independent control of HRT and SRT is effective for efficient microalgae cultivation and carbon dioxide capture using treated sewage.

  8. A fluorene-modified porphyrin for efficient dye-sensitized solar cells.

    PubMed

    Wu, Cheng-Hua; Pan, Tsung-Yu; Hong, Shang-Hao; Wang, Chin-Li; Kuo, Hshin-Hui; Chu, Yang-Yun; Diau, Eric Wei-Guang; Lin, Ching-Yao

    2012-05-07

    Porphyrins bearing a polyaromatic or a heterocyclic group are prepared to study their fundamental and photovoltaic properties. Solar cells sensitized with a fluorene-modified porphyrin outperform other dyes in the series, reaching ~90% efficiency of N719 dye.

  9. A porous covalent porphyrin framework with exceptional uptake capacity of saturated hydrocarbons oil spill cleanup

    SciTech Connect

    Wang, Xi-Sen; Liu, Jian; Bonefont, Jean M.; Yuan, Da-Qiang; Thallapally, Praveen K.; Ma, Shengqian

    2013-01-21

    Yamamoto homo-coupling reaction of tetra(4-bromophenyl)porphyrin afforded a porous covalent porphyrin framework, PCPF-1, which features strong hydrophobicity and oleophilicity and demonstrates exceptional adsorptive capacities for saturated hydrocarbons and gasoline.

  10. Binding and photocleavage of cationic porphyrin-phenylpiperazine hybrids to DNA.

    PubMed

    Jia, Tao; Jiang, Zhong-Xing; Wang, Kai; Li, Zao-Ying

    2006-02-01

    The binding properties of cationic porphyrin-phenylpiperazine hybrids to calf thymus (CT) DNA were investigated by using absorption, fluorescence and circular dichroism (CD) spectra, and the apparent affinity binding constants (K(app)) of the porphyrins for CT DNA were determined by using a competition method with ethidium bromide (EB). Intercalation of porphyrin into CT DNA occurred when two phenylpiperazines were introduced at cis position onto the periphery of cationic porphyrin. The photocleavages of pBR322 plasmid DNA by the porphyrins were consistent with the values of K(app). With [porphyrin]/[DNA base pairs] ratio increased, the binding mode tended to be outside binding, and the cleavage abilities of the porphyrins varied. In the presence of sodium azide, a quencher of 1O2, the cleavage of DNA by the porphyrin of intercalation was less inhibited.

  11. Energy transfer to porphyrin derivative dopants in polymer light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Higgins, R. W. T.; Monkman, A. P.; Nothofer, H.-G.; Scherf, U.

    2002-01-01

    The device physics of bilayer polymer light-emitting diodes that utilize energy transfer to various porphyrin derivatives were investigated. The emissive host, α,ω-bis[N,N-di(4-methylphenyl) aminophenyl]-poly(9,9-bis(2-ethylhexyl)fluoren-2,7-diyl) (PF2/6am4), was doped to a variety of concentrations between 0.5 and 4 wt. % with 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin zinc(II) (ZnOEP), 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin palladium(II) (PdOEP), and 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (PtOEP). The electroluminescent devices showed a maximum external quantum efficiency (EQE) of 1.19%, 0.22%, 1.08%, and 2.75% for undoped APFO, PF2/6am4:ZnOEP, PF2/6am4:PdOEP, and PF2/6am4:PtOEP blends, respectively. We attribute this variation in performance of the blends to be a product of both the luminescence quantum yield of the dopant molecules, which we take from the literature as 0.065, 0.2, and 0.5 for ZnOEP, PdOEP, and PtOEP, respectively, and the dopant excited state lifetime. We observe that at high brightness the EQE of the doped devices falls below that of the undoped device and we attribute this high-end falloff in performance to the excited state lifetimes of the dopant molecules, which determine at which current density devices exhibit peak efficiency. Past this peak in efficiency, we propose that saturation of the dopant sites is the major factor in detrimental device performance, which has wide reaching consequences for any future design that utilizes energy transfer of dopant molecules.

  12. Manganese(III) Porphyrin-based Potentiometric Sensors for Diclofenac Assay in Pharmaceutical Preparations

    PubMed Central

    Vlascici, Dana; Pruneanu, Stela; Olenic, Liliana; Pogacean, Florina; Ostafe, Vasile; Chiriac, Vlad; Pica, Elena Maria; Bolundut, Liviu Calin; Nica, Luminita; Fagadar-Cosma, Eugenia

    2010-01-01

    Two manganese(III) porphyrins: manganese(III) tetraphenylporphyrin chloride and manganese(III)-tetrakis(3-hydroxyphenyl)porphyrin chloride were tested as ionophores for the construction of new diclofenac–selective electrodes. The electroactive material was incorporated either in PVC or a sol–gel matrix. The effect of different plasticizers and additives (anionic and cationic) on the potentiometric response was studied. The best results were obtained for the PVC membrane plasticized with dioctylphtalate and having sodium tetraphenylborate as a lipophilic anionic additive incorporated. The sensor response was linear in the concentration range 3 × 10−6 – 1 × 10−2 M with a slope of −59.7 mV/dec diclofenac, a detection limit of 1.5 × 10−6 M and very good selectivity coefficients. It was used for the determination of diclofenac in pharmaceutical preparations, by direct potentiometry. The results were compared with those obtained by the HPLC reference method and a good agreement was found between the two methods. PMID:22163384

  13. New frontiers in prostate cancer imaging: clinical utility of prostate-specific membrane antigen positron emission tomography.

    PubMed

    Afaq, Asim; Batura, Deepak; Bomanji, Jamshed

    2017-02-14

    Prostate-specific membrane antigen positron emission tomography (PSMA PET) is a relatively new method of imaging prostate cancer that increases diagnostic accuracy in detecting and guiding management in various stages of the disease pathway. Gallium-68-labelled PSMA PET has increased the sensitivity of detection of disease recurrence at low PSA levels, thus allowing an optimal window for salvage treatment. Apart from its use in disease recurrence, PSMA PET has the potential for increasing sensitivity and specificity for primary tumour localisation and in detecting lymph node disease, leading to a more accurate initial staging of the condition. In advanced disease, the use of PSMA PET may be able to assess response to treatment and also guide treatment with radionuclide therapy. Newer ligands under development might provide avenues for theranostic or personalised therapy applications with early data showing high PSA response rates. The rate of translation of PSMA PET into clinical practice has been remarkable. The use of this modality is likely to increase with future efforts to modify the radiotracer including (18)F labelling to improve availability.

  14. Porphyrin and bodipy molecular rotors as microviscometers

    NASA Astrophysics Data System (ADS)

    Kimball, Joseph Daniel, III

    Viscosity, a fluid's internal resistance to flow and resist molecular diffusion, is a fundamental property of fluid media. Determining the bulk viscosity of a fluid has been easy to relatively simple to accomplish for many years, yet in the recent decade there has been a focus on techniques to measure a fluid's microviscosity. Microviscosity differs from bulk viscosity such that microviscosity is the friction experienced by a single particle interacting with its micron-sized local environment. Macroscopic methods to evaluate the viscosity are well established, but methods to determine viscosity on the microscale level remains unclear. This work determines the viability of three molecular rotors designed as probes for microviscosity in organic media, ionic liquids, and in the cellular microenvironment. Understanding microviscosity is important because it one of the main properties of any fluid and thus has an effect on any diffusion related processes. A variety of mass and signal transport phenomena as well as intermolecular interactions are often governed by viscosity. Molecular rotors are a subclass of intramolecular charge transfer fluorophores which form a lower energy twisted state. This results in a charge separated species which is highly sensitive to its surrounding microenviroment's viscosity as high viscosity limits its ability to form this twisted state. Once excited, there are deactivation routes which the excited fluorophore can undergo: radiative and non-radiative. Both were studied in this work. In the case of a radiative decay, as seen in porphyrin dimer, the energy is released in the form of a photon and is seen as a shifted band in the emission structure. The conformation of the porphyrin dimer was found to be influenced differently by ionic liquids as compared to molecular solvents, indicating the microheterogenous nature of ionic liquids play a role in the conformation. For non-radiative decays, BODIPY dyads and triads were investigated. The

  15. Synthesis of nanometer-scale porphyrin wheels of variable size.

    PubMed

    Hori, Takaaki; Peng, Xiaobin; Aratani, Naoki; Takagi, Akihiko; Matsumoto, Takuya; Kawai, Tomoji; Yoon, Zin Seok; Yoon, Min-Chul; Yang, Jaesung; Kim, Dongho; Osuka, Atsuhiro

    2008-01-01

    Starting from 1,3-phenylene linked diporphyrin zinc(II) complex 2ZA, repeated stepwise Ag I-promoted coupling reactions provided linear oligomers from 2nZA up to 128ZA. Of these zigzag shaped porphyrin arrays, the Ag I-promoted intramolecular cyclization reaction of 2 nZA (n=5, 6, 8, 9, 12, and 16) under dilute conditions gave the corresponding cyclic porphyrin wheels C2nZA (n=5, 6, 8, 9, 12, and 16), whereas large arrays 2nZA (n=24, 32, and 48) did not provide cyclic porphyrin products. These large discrete porphyrin arrays and wheels were fully characterized by means of 1H NMR spectroscopy, MALDI-TOF mass spectrometry, UV/Vis absorption spectroscopy, GPC-HPLC analysis, and the scanning tunneling microscopy (STM) technique. The STM images of C12ZA and C18ZA reveal their large circular structures. In the cyclic structures of C2nZA in solution, however, the gradual decrease in fluorescence quantum yields and fluorescence lifetimes are observed, reflecting some conformational heterogeneities. Collectively, the present work provides an important contribution to the construction of fully covalently linked large cyclic arranged porphyrin arrays with ample electronic interactions as a model of light-harvesting antenna.

  16. Chemical sensitivity of self-assembled porphyrin nano-aggregates.

    PubMed

    Dini, Francesca; Martinelli, Eugenio; Pomarico, Giuseppe; Paolesse, Roberto; Monti, Donato; Filippini, Daniel; D'Amico, Arnaldo; Lundström, Ingemar; Di Natale, Corrado

    2009-02-04

    Nanostructured molecular assemblies may provide additional sensing properties not found in other arrangements of the same basic constituents. Among three-dimensional structures, nanotubes are particularly appealing for applications as chemical sensors, because of the potential inclusion of different guests inside the cavity or the induced modification of the skeletal interaction after analyte binding. Porphyrins are a class of compounds characterized by brilliant sensing properties, appearing also in non-ordered solid-state aggregates. In recent years, it was reported that aggregation of oppositely charged porphyrins led to the formation of self-assembled nanotubes and in this paper their sensing properties, both in solution and in the solid state, have been investigated. The interactions of porphyrin nanotubes with guest molecules have been monitored by following the changes in their UV-vis spectra. The results obtained have been exploited to build up a sensing platform based on a computer screen as a light source and a digital camera as detector. Porphyrin nanostructures exhibited an enhanced sensitivity to different compounds with respect to those shown by single porphyrin subunits. The reason for the increased sensitivity may be likely found in an additional sensing mechanism related to the modulation of the strength of the forces that keep the supramolecular ensemble together.

  17. Fluorescence spectroscopy for endogenous porphyrins in human facial skin

    NASA Astrophysics Data System (ADS)

    Seo, I.; Tseng, S. H.; Cula, G. O.; Bargo, P. R.; Kollias, N.

    2009-02-01

    The activity of certain bacteria in skin is known to correlate to the presence of porphyrins. In particular the presence of coproporphyrin produced by P.acnes inside plugged pores has been correlated to acne vulgaris. Another porphyrin encountered in skin is protoporphyrin IX, which is produced by the body in the pathway for production of heme. In the present work, a fluorescence spectroscopy system was developed to measure the characteristic spectrum and quantify the two types of porphyrins commonly present in human facial skin. The system is comprised of a Xe lamp both for fluorescence excitation and broadband light source for diffuse reflectance measurements. A computer-controlled filter wheel enables acquisition of sequential spectra, first excited by blue light at 405 nm then followed by the broadband light source, at the same location. The diffuse reflectance spectrum was used to correct the fluorescence spectrum due to the presence of skin chromophores, such as blood and melanin. The resulting fluorescence spectra were employed for the quantification of porphyrin concentration in a population of healthy subjects. The results show great variability on the concentration of these porphyrins and further studies are being conducted to correlate them with skin conditions such as inflammation and acne vulgaris.

  18. Synthesis and antiprotozoal activity of original porphyrin precursors and derivatives.

    PubMed

    Abada, Zahra; Cojean, Sandrine; Pomel, Sébastien; Ferrié, Laurent; Akagah, Bernardin; Lormier, Anh Tuan; Loiseau, Philippe M; Figadère, Bruno

    2013-09-01

    Importance of heme in African trypanosomes, Leishmania sp. and Plasmodium sp. metabolisms justifies considering the potential of porphyrins and their precursors and derivatives as potential antiparasitic agents by interfering with heme metabolism. Consequently, twenty-four porphyrin precursors and derivatives were evaluated against Leishmania donovani, Trypanosoma brucei and Plasmodium sp. The best active compound against Trypanosoma brucei brucei was a new porphyrin derivative; compound 4i, with a MEC value of 6.25 μM justifying further in vivo evaluation. Whereas these compounds were not active against intramacrophage amastigotes of L. donovani, another new porphyrin derivative, compound 4f was active in vitro against Plasmodium falciparum at 20 nM and a slight delay of mice survival was observed on the Plasmodium berghei/Swiss mice model at 50 μmol/kg/day × 4. Pharmacomodulations should be further developed relying on a better knowledge on the porphyrin behaviour into the parasites comparatively to host cells.

  19. Synthesis and spectroscopic properties of a soluble semiconducting porphyrin polymer.

    PubMed

    Schmitz, Robert A; Liddell, Paul A; Kodis, Gerdenis; Kenney, Michael J; Brennan, Bradley J; Oster, Nolan V; Moore, Thomas A; Moore, Ana L; Gust, Devens

    2014-09-07

    A semiconducting porphyrin polymer that is solution processable and soluble in organic solvents has been synthesized, and its spectroscopic and electrochemical properties have been investigated. The polymer consists of diarylporphyrin units that are linked at meso-positions by aminophenyl groups, thus making the porphyrin rings an integral part of the polymer backbone. Hexyl chains on two of the aryl groups impart solubility. The porphyrin units interact only weakly in the ground electronic state. Excitation produces a local excited state that rapidly evolves into a state with charge-transfer character (CT) involving the amino nitrogen and the porphyrin macrocycle. Singlet excitation energy is transferred between porphyrin units in the chain with a time constant of ca. 210 ps. The final CT state has a lifetime of several nanoseconds, and the first oxidation of the polymer occurs at ca. 0.58 V vs. SCE. These properties make the polymer a suitable potential excited state electron donor to a variety of fullerenes or other acceptor species, suggesting that the polymer may find use in organic photovoltaics, sensors, and similar applications.

  20. Free erythrocyte porphyrins in cord blood.

    PubMed

    Gottuso, M A; Oski, B F; Oski, F A

    1978-05-01

    Red cell free erythrocyte porphyrin determinations were performed on cord blood specimens from 236 term infants and on capillary blood specimens from 63 preterm infants weighing less than 1,500 gm, during the first week of life. These results were contrasted with those obtained from 398 normal infants and children ages 1 to 6 years. The mean FEP value for the infants was significantly higher than that observed in the normal control subjects. In 10.5% of the term infants and 15.9% of the preterm infants, values in excess of 120 microgram/dl RBCs, the highest value recorded in the normal subjects, were observed. Elevations in FEP values were not related to either blood lead concentration or hematocrit levels in the infants. Infants with elevated FEP values were found to have lower serum iron and transferrin saturation values than did infants with low FEP values. These findings suggest that elevations in cord blood FEP values may indicate a state of relative iron deficiency present at birth.

  1. Anion permselective membrane

    NASA Astrophysics Data System (ADS)

    Hodgdon, R. B.; Waite, W. A.; Alexander, S. S.

    1984-07-01

    Two polymer ion exchange membranes were synthesized to fulfill the needs of both electrical resistivity and anolyte/catholyte separation for utility load leveling utilizing the DOE/NASA mixed electrolyte REDOX battery. Both membranes were shown to meet mixed electrolyte utility load leveling criteria. Several modifications of an anion exchange membrane failed to meet utility load leveling REDOX battery criteria using the unmixed electrolyte REDOX cell.

  2. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

    Hodgdon, R. B.; Waite, W. A.; Alexander, S. S.

    1984-01-01

    Two polymer ion exchange membranes were synthesized to fulfill the needs of both electrical resistivity and anolyte/catholyte separation for utility load leveling utilizing the DOE/NASA mixed electrolyte REDOX battery. Both membranes were shown to meet mixed electrolyte utility load leveling criteria. Several modifications of an anion exchange membrane failed to meet utility load leveling REDOX battery criteria using the unmixed electrolyte REDOX cell.

  3. Utilization of "Stand-By" Extracorporeal Membrane Oxygenation in a High-Risk Parturient With Methamphetamine-Associated Cardiomyopathy Undergoing Dilation and Evacuation: A Case Report.

    PubMed

    Padilla, Cesar; Hernandez Conte, Antonio; Ramzy, Danny; Lubin, Lorraine; LaBounty, Troy; Chung, Judith H; Zeng, Ying

    2017-03-01

    Parturients may present with evidence of acute heart failure or respiratory distress during the peripartum period. This case report documents utilization of "stand-by" extracorporeal membrane oxygenation (ECMO) for a 40-year-old woman with a history of severe left ventricular dysfunction who presented for elective dilation and evacuation of triplets at 20 weeks' gestation. The patient's medical history was significant for hypertension, diabetes mellitus, methamphetamine use (acute/chronic), and cardiac-respiratory arrest before her previous emergent cesarean delivery. The patient underwent general anesthesia with the placement of peripheral venous and arterial cannulas for "stand-by" ECMO. The patient remained stable throughout the procedure, and "stand-by" ECMO was not initiated; the patient was discharged 5 days' postprocedure. The use of "stand-by" ECMO in the parturient with severe cardiopulmonary dysfunction is still in its infancy. Centers managing populations of both high-risk parturients and nonparturients may consider development of algorithms for implementation and utilization of ECMO.

  4. Interfacial organization of achiral porphyrins via unidirectional compression: a general method for chiroptical porphyrin assemblies of selected chirality.

    PubMed

    Zhang, Xiao; Wang, Yanping; Chen, Penglei; Rong, Yunlong; Liu, Minghua

    2016-05-18

    Porphyrins are considered to be important scaffolds bridging supramolecular chemistry and chiral chemistry, where chirality selection via physical effects such as directional stirring and spin-coating has aroused particular interest. Nevertheless, these protocols could only work on a limited number of achiral porphyrins. It still remains a formidable challenge to pave a general avenue for the construction of chiral assemblies using achiral porphyrins. By means of a unique Langmuir-Schaefer (LS) technique of a unidirectional compression configuration, we herein have demonstrated that a series of achiral porphyrins could be facilely organized to form chiral interfacial assemblies of controlled supramolecular chirality. It has been disclosed that such a fascinating chirality selection scenario is intimately related to the direction of the compression-generated vortex-like flow, while the compression speed, one of the most significant parameters of the Langmuir technique, contributes less to this issue. With regard to a surface-pressure-dependent chirality selection phenomenon, it is suggested that the directional vortex-like flow generated by lateral compression might play a role in promoting the preferential growth of chiral assemblies showing an enhanced yet controlled CD signal. Our protocol might be, to some extent, a general method for achieving chiral porphyrin assemblies of controlled chirality.

  5. In vivo studies in NCT with a boronated porphyrin and tumor growth delay as an end point

    SciTech Connect

    Laster, B.H. State Univ. of New York, Stony Brook, NY . Dept. of Radiation Oncology); Kahl, S.B. . Dept. of Pharmaceutical Chemistry); Warkentien, L.; Bond, V.P. )

    1992-01-01

    The robust carrying capacity of the porphyrin molecule and its propensity for localizing in tumor justified the synthesizing of a porphyrin labeled with boron for use in BNCT. However, problems associated with poor solubility impeded the utility of the molecule. Until BOPP was synthesized porphyrins were promising, but impractical. After in vitro experiments had demonstrated the biological efficacy of BOPP and had confirmed its intracellular localizing ability in vivo studies were carried out using mice. Irradiation of KHJJ murine mammary carcinoma to the TCD[sub 50] in a single fraction was precluded since this whole body dose is lethal. This problem was overcome by the use of radiation. BOPP was administered either as three 0.5 ml injections per day over two days or by continuous i.v. infusion, 2 ml per day over three days for a total dose of about 42 [mu]g [sup 10]B/gbw. Boron-10 distribution in the tumor at the time of irradiation was [approximately]20 [mu]g.

  6. In vivo studies in NCT with a boronated porphyrin and tumor growth delay as an end point

    SciTech Connect

    Laster, B.H. |; Kahl, S.B.; Warkentien, L.; Bond, V.P.

    1992-12-31

    The robust carrying capacity of the porphyrin molecule and its propensity for localizing in tumor justified the synthesizing of a porphyrin labeled with boron for use in BNCT. However, problems associated with poor solubility impeded the utility of the molecule. Until BOPP was synthesized porphyrins were promising, but impractical. After in vitro experiments had demonstrated the biological efficacy of BOPP and had confirmed its intracellular localizing ability in vivo studies were carried out using mice. Irradiation of KHJJ murine mammary carcinoma to the TCD{sub 50} in a single fraction was precluded since this whole body dose is lethal. This problem was overcome by the use of radiation. BOPP was administered either as three 0.5 ml injections per day over two days or by continuous i.v. infusion, 2 ml per day over three days for a total dose of about 42 {mu}g {sup 10}B/gbw. Boron-10 distribution in the tumor at the time of irradiation was {approximately}20 {mu}g.

  7. Interaction of porphyrins with CdTe quantum dots.

    PubMed

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

    2011-05-13

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

  8. Conjugated Gold-Porphyrin Monolayers Assembled on Inorganic Surfaces.

    PubMed

    Gulino, Antonino; Contino, Annalinda; Giuseppe Maccarrone, Giuseppe Maccarrone; Fragalà, Maria Elena; Spitaleri, Luca

    2017-08-24

    Gold nanoparticles show important properties owing to their electronic structures. A limitation of some gold nanoparticles is that they either show surface plasmon or luminescence. In fact the increase in size of the gold nanoparticles and the appearing of the surface plasmon may result in the disappearance of luminescence. The aim of our study was the nanoscale assembly of Au nanoparticles on a monolayer of porphyrin molecules previously anchored to functionalized inorganic surfaces. This functional architecture not only exhibits a strong surface plasmon due to the gold nanoparticles but also a strong luminescence signal from porphyrin molecules. Finally we observed a long range order in the Au nanoparticles conjugated to the porphyrin monolayer. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Role of complement in porphyrin-induced photosensitivity

    SciTech Connect

    Lim, H.W.; Gigli, I.

    1981-01-01

    Addition of porphyrins to sera of guinea pigs in vitro, followed by irradiation with 405 nm light, resulted in dose-dependent inhibitions of hemolytic activity of complement. With guinea pig as an animal model, we also found that systemically administered porphyrins, followed by irradiation with 405 nm light, resulted in dose-dependent inhibition of CH50 in vivo. The erythrocytes from porphyrin-treated guinea pigs showed an increased susceptibility to hemolysis induced by 405 nm irradiation in vitro. Clinical changes in these animals were limited to light-exposed areas and consisted of erythema, crusting, and delayed growth of hair. Histologically, dermal edema, dilation of blood vessels, and infiltration of mononuclear and polymorphonuclear cells were observed. Guinea pigs irradiated with ultraviolet-B developed erythema, but had no alteration of their complement profiles. It is suggested that complement products may play a specific role in the pathogenesis of the cutaneous lesions of some porphyrias.

  10. Out-of-Plane Coordinated Porphyrin Nanotubes with Enhanced Singlet Oxygen Generation Efficiency

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang; Wang, Yao; Xu, Yanshuang; Yan, Yun; Huang, Jianbin

    2016-08-01

    A supramolecular porphyrin nanotube displaying J-aggregation feature was constructed by out-of-plane coordinated bismuth-porphyrin. Significantly, compared to traditional J-aggregated porphyrin suffering from fluorescence and singlet oxygen quenching, the nanotube exhibits excellent bio-imaging ability and enhanced production efficiency of singlet oxygen. The out-of-plane structure of bismuth to porphyrin makes the aggregation an appropriate material for theranostics. Furthermore, it is also a potential radio-therapeutic drug owing to the presence of radio-active bismuth. Thus, the self-assembly of out-of-plane coordinated porphyrin can be a facile approach toward effective therapy of tumors and other diseases.

  11. Mechanism and In Vivo Evaluation: Photodynamic Antibacterial Chemotherapy of Lysine-Porphyrin Conjugate

    PubMed Central

    Xu, Zengping; Gao, Yuxiang; Meng, Shuai; Yang, Baochen; Pang, Liyun; Wang, Chen; Liu, Tianjun

    2016-01-01

    Lysine-porphyrin conjugate 4i has potent photosensitive antibacterial effect on clinical isolated bacterial strains such as Methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa. The mechanism of photodynamic antibacterial chemotherapy of 4i (4i-PACT) in vitro and the treatment effect in vivo was investigated in this paper. Atomic force microscopy (AFM) revealed that 4i-PACT can effectively destroy membrane and wall of bacteria, resulting in leakage of its content. This was confirmed by dual fluorescent staining with acridine orange/ethidium bromide and measuring materials absorption at 260 nm. Agarose gel electrophoresis measurement showed that 4i-PACT can damage genomic DNA. Healing of wound in rat infected by mixed bacteria showed that the efficiency of 4i-PACT is dependent on the dose of light. These results showed that 4i-PACT has promising bactericidal effect both in vitro and in vivo. PMID:26973620

  12. Photodynamics of a constrained parachute-shaped fullerene-porphyrin dyad

    SciTech Connect

    Schuster, D.I.; Cheng, P.; Wilson, S.R.

    1999-12-15

    The pronounced ability of fullerene C{sub 60} to act as an electron and energy acceptor has led to the synthesis of a large number of compounds in which C{sub 60} is covalently linked to photoactivatable groups which can serve as potential donors. Such compounds are of interest as model systems for photosynthetic reaction centers and also have potential applications in photodynamic therapy because of the highly efficient photosensitization of singlet molecular oxygen formation by C{sub 60} and C{sub 60} derivatives. By far the largest number of such systems studied to date utilize porphyrins as antennas for efficient light capture in the visible region of the spectrum, and a variety of linkers. Photophysical studies as well as molecular modeling indicate that in conformationally flexible dyads the porphyrin (P) and C{sub 60} moieties are in close proximity, due to {pi}-stacking interactions, thus facilitating through-space interactions, as demonstrated by quenching of {sup 1}P{asterisk} fluorescence and generation of fullerene-excited states (by energy transfer) or P{sup +{sm{underscore}bullet}}-C{sub 60}{sup {minus}{sm{underscore}bullet}} ion-pair states (by electron transfer).

  13. Bulky melamine-based Zn-porphyrin tweezer as a CD probe of molecular chirality.

    PubMed

    Petrovic, Ana G; Vantomme, Ghislaine; Negrón-Abril, Yashira L; Lubian, Elisa; Saielli, Giacomo; Menegazzo, Ileana; Cordero, Roselynn; Proni, Gloria; Nakanishi, Koji; Carofiglio, Tommaso; Berova, Nina

    2011-10-01

    The transfer of chirality from a guest molecule to an achiral host is the subject of significant interest especially when, upon chiral induction, the chiroptical response of the host/guest complex can effectively report the absolute configuration (AC) of the guest. For more than a decade, dimeric metalloporphyrin hosts (tweezers) have been successfully applied as chirality probes for determination of the AC for a wide variety of chiral synthetic compounds and natural products. The objective of this study is to investigate the utility of a new class of melamine-bridged Zn-porphyrin tweezers as sensitive AC reporters. A combined approach based on an experimental CD analysis and a theoretical prediction of the prevailing interporphyrin helicity demonstrates that these tweezers display favorable properties for chiral recognition. Herein, we discuss the application of the melamine-bridged tweezer to the chiral recognition of a diverse set of chiral guests, such as 1,2-diamines, α-amino-esters and amides, secondary alcohols, and 1,2-amino-alcohols. The bulky periphery and the presence of a rigid porphyrin linkage lead, in some cases, to a more enhanced CD sensitivity than that reported earlier with other tweezers.

  14. Synthesis and characterization of "face-to-face" porphyrins.

    PubMed Central

    Collman, J P; Elliott, C M; Halbert, T R; Tovrog, B S

    1977-01-01

    The syntheses of four binary porphyrins, two of which are constrained to a "face-to-face" conformation, and their Co2+ and Cu2+ derivatives are described. Electron spin resonance indicates that the intermetallic separation in the binuclear "face-to-face" porphyrins is about 6.5-6.8 A. Electronic spectra and proton magnetic resonance spectra support the postulated "face-to-face" conformations. A hypothesis that related compounds may serve as multielectron redox catalysts for O2 and N2 is presented. PMID:189304

  15. Synthesis, Electrochemistry, and Photophysics of Aza-BODIPY Porphyrin Dyes.

    PubMed

    Pascal, Simon; Bucher, Léo; Desbois, Nicolas; Bucher, Christophe; Andraud, Chantal; Gros, Claude P

    2016-03-24

    The synthesis of dyad and triad aza-BODIPY-porphyrin systems in two steps starting from an aryl-substituted aza-BODIPY chromophore is described. The properties of the resulting aza-BODIPY-porphyrin conjugates have been extensively investigated by means of electrochemistry, spectroelectrochemistry, and absorption/emission spectroscopy. Fluorescence measurements have revealed a dramatic loss of luminescence intensity, mainly due to competitive energy transfer and photoinduced electron transfer involving charge separation followed by recombination. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Photoinduced conductivity of a porphyrin-gold composite nanowire

    SciTech Connect

    Kilina, Svletana; Balatsky, Alexander; Kilin, Dmitri S; Prezhdo, Oleg; Tsemekhman, Kiril

    2009-01-01

    Negatively charged phosphine groups on the backbone of DNA are known to attract gold nanoclusters from a colloid, assembling the clusters at fixed intervals. Bridging these intervals with porphyrin-dye linkers forms an infinite conducting chain, a quantum wire whose carrier mobility can be enhanced by photoexcitation. The resulting nanoassembly can be used as a gate: a wire with a controllable conductivity. The electronic structure of the porphyrin-gold wire is studied here by density functional theory, and the conductivity of the system is determined as a function of the photoexcitation energy. Photoexcitations of the dye are found to enhance the wire conductivity by orders of magnitude.

  17. Time resolved structural dynamics of butadiyne-linked porphyrin dimers

    PubMed Central

    Camargo, Franco V. A.; Hall, Christopher R.; Anderson, Harry L.; Meech, Stephen R.; Heisler, Ismael A.

    2016-01-01

    In this work, the timescales and mechanisms associated with the structural dynamics of butadiyne-linked porphyrin dimers are investigated through time resolved narrowband pump/broadband probe transient absorption spectroscopy. Our results confirm previous findings that the broadening is partly due to a distribution of structures with different (dihedral) angular conformations. Comparison of measurements with excitations on the red and blue sides of the Q-band unravel the ground and excited state conformational re-equilibration timescales. Further comparison to a planarized dimer, through the addition of a ligand, provides conclusive evidence for the twisting motion performed by the porphyrin dimer in solution. PMID:26798839

  18. Molecular nanostamp based on one-dimensional porphyrin polymers.

    PubMed

    Kanaizuka, Katsuhiko; Izumi, Atsushi; Ishizaki, Manabu; Kon, Hiroki; Togashi, Takanari; Miyake, Ryosuke; Ishida, Takao; Tamura, Ryo; Haga, Masa-aki; Moritani, Youji; Sakamoto, Masatomi; Kurihara, Masato

    2013-08-14

    Surface design with unique functional molecules by a convenient one-pot treatment is an attractive project for the creation of smart molecular devices. We have employed a silane coupling reaction of porphyrin derivatives that form one-dimensional polymer wires on substrates. Our simple one-pot treatment of a substrate with porphyrin has successfully achieved the construction of nanoscale bamboo shoot structures. The nanoscale bamboo shoots on the substrates were characterized by atomic force microscopy (AFM), UV-vis spectra, and X-ray diffraction (XRD) measurements. The uneven and rigid nanoscale structure has been used as a stamp for constructing bamboo shoot structures of fullerene.

  19. Influence of nonplanarity and extended conjugation on porphyrin basicity.

    PubMed

    Finikova, Olga S; Cheprakov, Andrei V; Carroll, Patrick J; Dalosto, Sergio; Vinogradov, Sergei A

    2002-12-30

    Thermodynamic basicities of several new nonplanar water soluble tetraaryltetracyclohexano- (Ar(4)TCHP) and tetraaryltetrabenzoporphyrins (Ar(4)TBP) have been measured and correlated with their structural parameters. While the degrees of nonplanarity in these porphyrins are similar, Ar(4)TCHPs exhibit significantly higher basicities than Ar(4)TBPs and than planar tetraarylporphyrins. Low basicities of distorted Ar(4)TBPs are believed to be due to extended pi-conjugation, which causes delocalization of the core electron density in these porphyrins and reduces negative charges at the protonation site.

  20. Micropatterning of porphyrin nanotubes thin film using focused laser writing.

    PubMed

    Gupta, Jyotsana; Lim, Xiaodai; Sow, Chorng-Haur; Vijayan, C

    2011-05-01

    We report an effective process to create micropatterns on a thin film of porphyrin nanotubes PNTs on Si substrate using focused laser beam. The optical properties of the newly synthesized porphyrin nanotubes are investigated and micropatterning is demonstrated using laser fabrication, an increasingly important tool in various fields of research. We made use of this laser cutting method to create interesting and useful two-dimensional patterned structures. The shapes and sizes of the structures created can be controlled by varying the power of the laser, angle of incident of the focused laser beam, the relative speed with which the laser beam traverse through the film and the magnification of objective lens used.

  1. Reductive precipitation of metals photosensitized by tin and antimony porphyrins

    DOEpatents

    Shelnutt, John A.; Gong, Weiliang; Abdelouas, Abdesselam; Lutze, Werner

    2003-09-30

    A method for reducing metals using a tin or antimony porphyrin by forming an aqueous solution of a tin or antimony porphyrin, an electron donor, such as ethylenediaminetetraaceticacid, triethylamine, triethanolamine, and sodium nitrite, and at least one metal compound selected from a uranium-containing compound, a mercury-containing compound, a copper-containing compound, a lead-containing compound, a gold-containing compound, a silver-containing compound, and a platinum-containing compound through irradiating the aqueous solution with light.

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

    PubMed

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

    2015-08-26

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

  3. A nonplanar porphyrin-based receptor molecule for chiral amine ligands

    SciTech Connect

    MUZZI,CINZIA M.; MEDFORTH,CRAIG J.; SMITH,KEVIN M.; JIA,SONG-LING; SHELNUTT,JOHN A.

    2000-03-06

    A novel porphyrin-based receptor molecule for chiral amine ligands is described in which nonplanarity of the porphyrin macrocycle is used to orient the ligand and to enhance porphyrin-ligand interactions. The porphyrin macrocycle provides a versatile platform upon which to build elaborate superstructures, and this feature coupled with a rich and well-developed synthetic chemistry has led to the synthesis of many elegant models of heme protein active sites and numerous porphyrin-based receptor molecules. One design feature which is not usually considered in the design of porphyrin-based receptor molecules is nonplanarity of the porphyrin ring, although there are a few systems such as the pyridine sensitive Venus Flytrap and the chirality-memory molecule which illustrate that nonplanar porphyrin-based receptors can display unique and interesting behavior. Given the novel properties of these receptors and the continuing interest in the effects of nonplanarity on the properties of porphyrins the authors decided to investigate in more detail the potential applications of nonplanarity in the design of porphyrin-based receptors. Herein, they describe the design, synthesis, and characterization of a new kind of nonplanar porphyrin-based receptor molecule for chiral amines.

  4. Porphyrin-cross-linked hydrogel for fluorescence-guided monitoring and surgical resection.

    PubMed

    Lovell, Jonathan F; Roxin, Aron; Ng, Kenneth K; Qi, Qiaochu; McMullen, Jesse D; DaCosta, Ralph S; Zheng, Gang

    2011-09-12

    We demonstrate that porphyrins can be used as efficient cross-linkers to generate a new class of hydrogels with enabling optical properties. Tetracarboxylic acid porphyrins reacted with PEG diamines to form a condensation polyamide in a range of appropriate conditions, with respect to reaction time, diisopropylethylamine initiator concentration, porphyrin-to-PEG ratio, porphyrin concentration, and PEG size. The network structure of the hydrogel maintained a porphyrin spacing that prevented excessive fluorescence self-quenching despite high porphyrin density. The near-infrared properties readily enabled low background, noninvasive fluorescence monitoring of the implanted hydrogel in vivo, as well as its image-guided surgical removal in real time using a low-cost fluorescence camera prototype. Emission could be tuned by incorporating copper metalloporphyrins into the network. The approach of creating hydrogels using cross-linking porphyrin comonomers creates opportunities for new polymer designs with strong optical character.

  5. Functional, photochemically active, and chemically asymmetric membranes by interfacial polymerization of derivatized multifunctional prepolymers

    DOEpatents

    Lonsdale, Harold K.; Wamser, Carl C.

    1988-01-01

    The preparation of a novel class of thin film membranes by interfacial polymerization is disclosed, said membanes incorporating as part of their polymeric structure the functionality of monomeric or oligomeric precursors. Specific embodiments include porphyrin and phthalocyanime derivatives that are photochemically or electrochemically active, as well as chemically asymmetric membranes.

  6. Laser flash photolysis generation and kinetic studies of porphyrin-manganese-oxo intermediates. Rate constants for oxidations effected by porphyrin-Mn(V)-oxo species and apparent disproportionation equilibrium constants for porphyrin-Mn(IV)-oxo species.

    PubMed

    Zhang, Rui; Horner, John H; Newcomb, Martin

    2005-05-11

    Porphyrin-manganese(V)-oxo and porphyrin-manganese(IV)-oxo species were produced in organic solvents by laser flash photolysis (LFP) of the corresponding porphyrin-manganese(III) perchlorate and chlorate complexes, respectively, permitting direct kinetic studies. The porphyrin systems studied were 5,10,15,20-tetraphenylporphyrin (TPP), 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TPFPP), and 5,10,15,20-tetrakis(4-methylpyridinium)porphyrin (TMPyP). The order of reactivity for (porphyrin)Mn(V)(O) derivatives in self-decay reactions in acetonitrile and in oxidations of substrates was (TPFPP) > (TMPyP) > (TPP). Representative rate constants for reaction of (TPFPP)Mn(V)(O) in acetonitrile are k = 6.1 x 10(5) M(-1) s(-1) for cis-stilbene and k = 1.4 x 10(5) M(-1) s(-1) for diphenylmethane, and the kinetic isotope effect in oxidation of ethylbenzene and ethylbenzene-d(10) is k(H)/k(D) = 2.3. Competitive oxidation reactions conducted under catalytic conditions display approximately the same relative rate constants as were found in the LFP studies of (porphyrin)Mn(V)(O) derivatives. The apparent rate constants for reactions of (porphyrin)Mn(IV)(O) species show inverted reactivity order with (TPFPP) < (TMPyP) < (TPP) in reactions with cis-stilbene, triphenylamine, and triphenylphosphine. The inverted reactivity results because (porphyrin)Mn(IV)(O) disproportionates to (porphyrin)Mn(III)X and (porphyrin)Mn(V)(O), which is the primary oxidant, and the equilibrium constants for disproportionation of (porphyrin)Mn(IV)(O) are in the order (TPFPP) < (TMPyP) < (TPP). The fast comproportionation reaction of (TPFPP)Mn(V)(O) with (TPFPP)Mn(III)Cl to give (TPFPP)Mn(IV)(O) (k = 5 x 10(8) M(-1) s(-1)) and disproportionation reaction of (TPP)Mn(IV)(O) to give (TPP)Mn(V)(O) and (TPP)Mn(III)X (k approximately 2.5 x 10(9) M(-1) s(-1)) were observed. The relative populations of (porphyrin)Mn(V)(O) and (porphyrin)Mn(IV)(O) were determined from the ratios of observed rate constants for

  7. Observation of vanadyl porphyrins and sulfur-containing vanadyl porphyrins in a petroleum asphaltene by atmospheric pressure photonionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Qian, Kuangnan; Mennito, Anthony S; Edwards, Kathleen E; Ferrughelli, Dave T

    2008-07-01

    Vanadyl (VO) porphyrins and sulfur-containing vanadyl (VOS) porphyrins of a wide carbon number range (C(26) to C(52)) and Z-number range (-28 to -54) were detected and identified in a petroleum asphaltene by atmospheric pressure photonionization (APPI) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). APPI provides soft ionization of asphaltene molecules (including VO and VOS porphyrins), generating primarily molecular ions (M(+.)). The ultra-high mass resolving power (m/Delta m(FWHM) approximately 500 K) of FTICR-MS enabled resolution and positive identification of elemental formulae for the entire family of VO and VOS porphyrins in a complicated asphaltene matrix. Deocophylerythro-etioporphyrin (DPEP) is found to be the most prevalent structure, followed by etioporphyrins (etio)- and rhodo (benzo)-DPEP. The characteristic Z-distribution of VO porphyrins suggests benzene and naphthene increment in the growth of porphyrin ring structures. Bimodal carbon number distributions of VO porphyrins suggest possible different origins of low and high molecular weight species. To our knowledge, the observation of VOS porphyrins in a petroleum product has not previously been reported. The work is also the first direct identification of the entire vanadyl porphyrin family by ultra-high resolution mass spectrometry without chromatographic separation or demetallation.

  8. Fast electronic relaxation in lathanide porphyrins

    NASA Astrophysics Data System (ADS)

    Tsvirko, M. P.; Stelmakh, G. F.; Pyatosin, V. E.; Solovyov, K. N.; Kachura, T. F.; Piskarskas, A. S.; Gadonas, R. A.

    1986-08-01

    The photophysical processes in porphyrin complexes of lanthanides (Ln) and their correlation with Ln 3+ ion characteristics have been studied by picosecond transient spectroscopy and spectrofluorimetry. The lifetimes of the S 2, S 1 and T 1 π-electron states have been determined for the Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu complexes of tetrabenzporphin (TBP). Depending on the nature of the Ln 3+ ion the non-radiative decay rates of the Ln TBP (π, π*) states vary by several orders of magnitude: from 3 × 10 11 to > 2 × 10 13 s -1 for the S 2 decay, from 2 × 10 10 to > 2 × 10 11 s -1 for the S 1 decay and from 6 × 10 2 to 3 × 10 10 s -1 for the T 1 decay. The T 1 deactivation rate constant of paramagnetic complexes decreases exponentially with the energy gap between the T 1 level and the nearest lower-lying accepting 4f-level beginning with Δ E ≈ 4000 cm -1. For Δ E < 4000 cm -1 there is a tendency toward stabilization of the τ -1T values. By example of the Dy, Tb, Ho, Er and Tm complexes it is shown that combination states, in which the Ln 3+_ ion and the macrocyclic ligand are excited simultaneously, participate in the deactivation of the S 2 and S 1 states. The anomalously high rates of deactivation of the S 2, S 1 and T 1 states in the case of Eu, Yb and Sm complexes are due to the charge-transfer states involved in relaxation processes.

  9. Potentiometric behaviour of ion selective electrodes based on iron porphyrins: the influence of porphyrin substituents on the response properties and analytical determination of diclofenac in pharmaceutical formulations.

    PubMed

    Santos, Emília M G; Araújo, Alberto N; Couto, Cristina M C M; Montenegro, M Conceição B S M

    2006-11-16

    The potentiometric response characteristics of diclofenac selective electrodes based on Fe(III) tetraphenylporphyrin-chloride (Fe(III)TPP-Cl) and Fe(III) tetrakis(pentafluorophenyl)porphyrin-chloride (Fe(III)TPFPP-Cl) in different mediator solvents and ionic additives are compared. The sensitivity, working range, detection limit, response mechanism, and selectivity of the membrane sensor show a significant dependence on the type of carrier substituent and on the pH value of the sample solution. Studies performed with different amounts of cationic additive (tetra-n-octylammoniumbromide (TOABr)) and anionic additive (sodium tetraphenylborate (NaTPB)) in the membranes allowed the determination of the potentiometric mechanism of action of the used metalloporphyrins. For the analysis of real samples, Fe(III)TPFPP-Cl (type G), prepared in o-NPOE, incorporating 10 mol% of TOABr, was used. This potentiometric unit presented a linear response towards diclofenac concentrations between 10(-5) and 10(-2)mol l(-1) ( I=0.1 mol l(-1)) and slopes of about -59 mV dec(-1), exhibiting a response time of 10s in a buffered solution of ammonia-ammonium sulphate with pH 9.9. The potentiometric analysis of sodium diclofenac in pharmaceutical formulations was carried out by direct potentiometry and the obtained results were compared to those provided by HPLC, presenting relative errors inferior to 1.0%.

  10. Porphyrin involvement in redshift fluorescence in dentin decay

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  11. 21 CFR 862.1595 - Porphyrins test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Porphyrins test system. 862.1595 Section 862.1595 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... treatment of lead poisoning, porphyrias (primarily inherited diseases associated with disturbed...

  12. 21 CFR 862.1595 - Porphyrins test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Porphyrins test system. 862.1595 Section 862.1595 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... treatment of lead poisoning, porphyrias (primarily inherited diseases associated with disturbed...

  13. Modulation of Group I Ribozyme Activity by Cationic Porphyrins

    PubMed Central

    Matsumura, Shigeyoshi; Ito, Tatsunobu; Tanaka, Takahiro; Furuta, Hiroyuki; Ikawa, Yoshiya

    2015-01-01

    The effects of cationic porphyrins on the catalytic activities of four group I ribozymes were investigated. A cationic porphyrin possessing four pyridinium moieties (pPyP) inhibited two group IC3 ribozymes (Syn Rz and Azo Rz) and a group IC1 ribozyme (Tet Rz). In the case of a group IA2 ribozyme (Td Rz), however, pPyP served not only as an inhibitor but also as an activator, and the effects of pPyP were dependent on its concentration. To analyze the structural and electronic factors determining the effects of pPyP on group I ribozymes, three cationic porphyrins (pPyNCP, pPyF4P, and TMPyP) were also examined. As interactions between small organic molecules and nucleic acids are attractive and important issues in biochemistry and biotechnology, this study contributes to the development of porphyrin-based molecules that can modulate functions of structured RNA molecules. PMID:25811638

  14. Synthesis of metallic nanoshells on porphyrin-stabilized emulsions

    DOEpatents

    Wang, Haorong; Song, Yujiang; Shelnutt, John A.; Medforth, Craig J.

    2011-12-13

    Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.

  15. An expeditious synthesis of tailed tren-capped porphyrins.

    PubMed

    Even, Pascale; Ruzié, Christian; Ricard, David; Boitrel, Bernard

    2005-09-29

    [structure: see text] A one-pot two-step versatile synthesis of tailed tren-capped porphyrins has been achieved. The two resulting ligands demonstrate that this expeditious method can be applied to various axial bases to obtain highly functionalized macromolecules attractive for heme modeling purposes. Dioxygen binding of the pyridine-tailed iron complex is reported as a direct application.

  16. Hexamodal imaging with porphyrin-phospholipid-coated upconversion nanoparticles.

    PubMed

    Rieffel, James; Chen, Feng; Kim, Jeesu; Chen, Guanying; Shao, Wei; Shao, Shuai; Chitgupi, Upendra; Hernandez, Reinier; Graves, Stephen A; Nickles, Robert J; Prasad, Paras N; Kim, Chulhong; Cai, Weibo; Lovell, Jonathan F

    2015-03-11

    Hexamodal imaging using simple nanoparticles is demonstrated. Porphyrin-phospholipids are used to coat upconversion nanoparticles in order to generate a new biocompatible material. The nanoparticles are characterized in vitro and in vivo for imaging via fluorescence, upconversion, positron emission tomography, computed tomography, Cerenkov luminescence, and photoacoustic tomography.

  17. Porphyrin Induced Laser Deactivation of Trypsinogen-Trypsin Conversion

    NASA Astrophysics Data System (ADS)

    Perido, Joanna; Brancaleon, Lorenzo

    2015-03-01

    Pancreatitis is caused by the inflammation of the pancreas, where the digestive enzyme trypsin is activated from the precursor enzyme trypsinogen while still in the pancreas. The presence of trypsin in the pancreas causes auto-activation of trypsinogen, resulting in greater inflammation and auto-digestion of the pancreas. In severe cases, this cascade effect can lead to organ failure, diabetes, and pancreatic cancer. Our hypothesis is that if trypsinogen is prevented from auto-activating into trypsin, then this cascade can be stopped. We propose to do this by inducing conformational changes in trypsinogen when bound to a photoactive porphyrin dye. Porphyrins are comprised of four linked heterocyclic groups forming a flat ring, and bind well with proteins such as trypsinogen. In this study we used spectroscopic techniques to probe the binding of meso-tetrakis (4-sulfonatephenyl) porphyrin (TSPP) to trypsinogen in vitro, as a preliminary step to then prompt and characterize conformational changes of trypsinogen through irradiation. If conformational changes are detected the trypsinogen will be tested for trypsin inactivation. This investigation may provide promising initial results to the possible use of porphyrins as an inhibitor of the self-activation of trypsinogen into trypsin, and a potential inhibitor of pancreatitis. MARC*U-STAR.

  18. Bis(porphyrin)-anthraquinone triads: synthesis, spectroscopy, and photochemistry.

    PubMed

    Giribabu, L; Reeta, P Silviya; Kanaparthi, Ravi Kumar; Srikanth, Malladi; Soujanya, Y

    2013-04-11

    Molecular triads based on bis(porphyrin)-anthraquinone having azomethine bridge at the pyrrole-β position have been designed and synthesized. Both free-base AQ-(H2)2 and zinc AQ-(Zn)2 triads are characterized by elemental analysis, MALDI-MS, (1)H NMR, UV-visible, and fluorescence spectroscopy (steady-state and time-resolved) as well as electrochemical method. The absorption spectra of both Soret and Q-bands of the triads are red-shifted by 12-20 nm with respect to their monomer units. The study supported by theoretical calculations manifests that there exists a negligible electronic communication in the ground state between the donor porphyrin and acceptor anthraquinone of these triads. However, interestingly, both the triads exhibit significant fluorescence emission quenching (51-92%) of the porphyrin emission compared to their monomeric units. The emission quenching is attributed to the excited-state intramolecular photoinduced electron transfer from porphyrins to anthraquinone. The electron-transfer rates (kET) of these triads are found in the range 1.0 × 10(8) to 7.7 × 10(9) s(-1) and are found to be solvent dependent.

  19. Condensed phase photoacoustic spectroscopic detection of porphyrins and dyes

    SciTech Connect

    Voigtman, E.; Jurgensen, A.; Winefordner, J.

    1981-08-01

    A simple piezoelectric detection system suitable for performing highly sensitive liquid-phase photoacoustic spectroscopy is presented. Performance of the system with respect to linearity, solvent effects, and excitation pulse characteristics is experimentally evaluated and compared with theoretical figures of merit. Limits of detection for various porphyrins, laser dyes, and drugs are presented.

  20. Utilization of photoinduced charge-separated state of donor-acceptor-linked molecules for regulation of cell membrane potential and ion transport.

    PubMed

    Numata, Tomohiro; Murakami, Tatsuya; Kawashima, Fumiaki; Morone, Nobuhiro; Heuser, John E; Takano, Yuta; Ohkubo, Kei; Fukuzumi, Shunichi; Mori, Yasuo; Imahori, Hiroshi

    2012-04-11

    The control of ion transport across cell membranes by light is an attractive strategy that allows targeted, fast control of precisely defined events in the biological membrane. Here we report a novel general strategy for the control of membrane potential and ion transport by using charge-separation molecules and light. Delivery of charge-separation molecules to the plasma membrane of PC12 cells by a membranous nanocarrier and subsequent light irradiation led to depolarization of the membrane potential as well as inhibition of the potassium ion flow across the membrane. Photoregulation of the cell membrane potential and ion transport by using charge-separation molecules is highly promising for control of cell functions. © 2012 American Chemical Society

  1. Porphyrin Depth in Lipid Bilayers as Determined by Iodide and Parallax Fluorescence Quenching Methods and Its Effect on Photosensitizing Efficiency

    PubMed Central

    Bronshtein, Irena; Afri, Michal; Weitman, Hana; Frimer, Aryeh A.; Smith, Kevin M.; Ehrenberg, Benjamin

    2004-01-01

    Photosensitization by porphyrins and other tetrapyrrole chromophores is used in biology and medicine to kill cells. This light-triggered generation of singlet oxygen is used to eradicate cancer cells in a process dubbed “photodynamic therapy,” or PDT. Most photosensitizers are of amphiphilic character and they partition into cellular lipid membranes. The photodamage that they inflict to the host cell is mainly localized in membrane proteins. This photosensitized damage must occur in competition with the rapid diffusion of singlet oxygen through the lipid phase and its escape into the aqueous phase. In this article we show that the extent of damage can be modulated by employing modified hemato- and protoporphyrins, which have alkyl spacers of varying lengths between the tetrapyrrole ring and the carboxylate groups that are anchored at the lipid/water interface. The chromophore part of the molecule, and the point of generation of singlet oxygen, is thus located at a deeper position in the bilayer. The photosensitization efficiency was measured with 9,10-dimethylanthracene, a fluorescent chemical target for singlet oxygen. The vertical insertion of the sensitizers was assessed by two fluorescence-quenching techniques: by iodide ions that come from the aqueous phase; and by spin-probe-labeled phospholipids, that are incorporated into the bilayer, using the parallax method. These methods also show that temperature has a small effect on the depth when the membrane is in the liquid phase. However, when the bilayer undergoes a phase transition to the solid gel phase, the porphyrins are extruded toward the water interface as the temperature is lowered. These results, together with a previous publication in this journal, represent a unique and precedental case where the vertical location of a small molecule in a membrane has an effect on its membranal activity. PMID:15298918

  2. Electronic Structure and Dynamics of Nitrosyl Porphyrins

    PubMed Central

    Scheidt, W. Robert; Barabanschikov, Alexander; Pavlik, Jeffrey W.; Silvernail, Nathan J.; Sage, J. Timothy

    2010-01-01

    Nitric oxide (NO) is a signalling molecule employed to regulate essential physiological processes. Thus, there is great interest in understanding the interaction of NO with heme, which is found at the active site of many proteins that recognize NO, as well those involved in its creation and elimination. We summarize what we have learned from investigations of the structure, vibrational properties, and conformational dynamics of NO complexes with ferrous porphyrins, as well as computational investigations in support of these experimental studies. Multi-temperature crystallographic data reveals variations in the orientational disorder of the nitrosyl ligand. In some cases, equilibria among NO orientations can be analyzed using the vant Hoff relationship and the free energy and the enthalpy of the solid-state transitions evaluated experimentally. DFT calculations predict that intrinsic barriers to torsional rotations are smaller than thermal energies at physiological temperatures, and the coincidence of observed NO orientations with minima in molecular mechanics potentials indicates that nonbonded interactions with other chemical groups control the conformational freedom of the bound NO. In favorable cases, reduced disorder at low temperatures exposes subtle structural features including off-axis tilting of the Fe–NO bond and anisotropy of the equatorial Fe–N bonds. We also present the results of nuclear resonance vibrational spectroscopy (NRVS) measurements on oriented single crystals of [Fe(TPP)(NO)] and [Fe(TPP)(1-MeIm)(NO)]. These describe the anisotropic vibrational motion of Fe in five-and six-coordinate heme-NO complexes, and reveal vibrations of all Fe-ligand bonds as well as low frequency molecular distortions associated with the doming of the heme upon ligand binding. Quantitative comparison with predicted frequencies, amplitudes and directions facilitates identification of vibrational modes, but also suggests that commonly used DFT functionals are not

  3. Electronic structure and dynamics of nitrosyl porphyrins.

    PubMed

    Scheidt, W Robert; Barabanschikov, Alexander; Pavlik, Jeffrey W; Silvernail, Nathan J; Sage, J Timothy

    2010-07-19

    Nitric oxide (NO) is a signaling molecule employed to regulate essential physiological processes. Thus, there is great interest in understanding the interaction of NO with heme, which is found at the active site of many proteins that recognize NO, as well as those involved in its creation and elimination. We summarize what we have learned from investigations of the structure, vibrational properties, and conformational dynamics of NO complexes with ferrous porphyrins, as well as computational investigations in support of these experimental studies. Multitemperature crystallographic data reveal variations in the orientational disorder of the nitrosyl ligand. In some cases, equilibria among NO orientations can be analyzed using the van't Hoff relationship and the free energy and enthalpy of the solid-state transitions evaluated experimentally. Density functional theory (DFT) calculations predict that intrinsic barriers to torsional rotation are smaller than thermal energies at physiological temperatures, and the coincidence of observed NO orientations with minima in molecular mechanics potentials indicates that nonbonded interactions with other chemical groups control the conformational freedom of the bound NO. In favorable cases, reduced disorder at low temperatures exposes subtle structural features including off-axis tilting of the Fe-NO bond and anisotropy of the equatorial Fe-N bonds. We also present the results of nuclear resonance vibrational spectroscopy measurements on oriented single crystals of [Fe(TPP)(NO)] and [Fe(TPP)(1-MeIm)(NO)]. These describe the anisotropic vibrational motion of iron in five- and six-coordinate heme-NO complexes and reveal vibrations of all Fe-ligand bonds as well as low-frequency molecular distortions associated with the doming of the heme upon ligand binding. A quantitative comparison with predicted frequencies, amplitudes, and directions facilitates identification of the vibrational modes but also suggests that commonly used DFT

  4. Comparison of maturity based on steroid and vanadyl porphyrin parameters: A new vanadyl porphyrin maturity parameter for higher maturities

    NASA Astrophysics Data System (ADS)

    Sundararaman, Padmanabhan; Moldowan, J. Michael

    1993-03-01

    Correlations are demonstrated between steroid maturity parameters and the porphyrin maturity parameter (PMP) which is based on the ratio of specific vanadyl porphyrins C 28E /(C 28E + C 32D) measured by HPLC. Measurements from a global selection of > 100 rock extracts and oils show that PMP parallels changes in the C 29-sterane 20S/(20S + 20R) and tri/(tri + mono) aromatic steroid ratios, and that all three parameters appear to attain their maximum values at similar maturity levels. The triaromatic steroid side chain cracking parameter, TA I/(I + II), reaches approximately 20% of its maximum value when PMP has reached 100%. These results suggest that PMP is effective in the early to peak portion of the oil window. A new parameter, PMP-2, based on changes in the relative concentrations of two peaks in the HPLC fingerprint (vanadyl "etio" porphyrins), appears effective in assessing the maturity of source rocks beyond peak oil generation. In combination with PMP this parameter extends the effective range of vanadyl porphyrins parameters to higher maturities as demonstrated by a suite of oils from the Oriente Basin, Ecuador, South America.

  5. Comparison of maturity based on steroid and vanadyl porphyrin parameters: A new vanadyl porphyrin maturity parameter for higher maturities

    SciTech Connect

    Sundararaman, P. ); Moldowan, J.M. )

    1993-03-01

    Correlations are demonstrated between steriod maturity parameters and the porphyrin maturity parameter (PMP) which is based on the ratio of specific vanadyl porphyrins C[sub 28]E/(C[sub 28]E + C[sub 32]D) measured by HPLC. Measurements from a global selection of >100 rock extracts and oils show that PMP parallels changes in the C[sub 29]-sterane 20S/(20S + 20R) and tri/(tri + mono) aromatic steroid ratios, and that all three parameters appear to attain their maximum values at similar maturity levels. The triaromatic steroid side chain cracking parameter, TA I/(I + II), reaches approximately 20% of its maximum value when PMP has reached 100%. These results suggest that PMP is effective in the early to peak portion of the oil window. A new parameter, PMP-2, based on changes in the relative concentrations of two peaks in the HPLC fingerprint (vanadyl [open quotes]etio[close quotes] porphyrins), appears effective in assessing the maturity of source rocks beyond peak oil generation. In combination with PMP this parameter extends the effective range of vanadyl porphyrins parameters to higher maturities as demonstrated by a suite of oils from the Oriente Basin, Ecuador, South America. 22 refs., 6 figs., 1 tab.

  6. Novel Porphyrinic Porous Organic Frameworks for High Performance Separation of Small Hydrocarbons

    PubMed Central

    Ma, Heping; Ren, Hao; Meng, Shuang; Sun, Fuxing; Zhu, Guangshan

    2013-01-01

    A series of Porphyrinic-CTF materials are synthesized under ionothermal condition with high surface areas (>3200 m2/g) and tunable pore sizes. The ZnP-CTFs exhibit high adsorption capacities and selectivity towards C3H8, and C2H6 over CH4 as IAST prediction. Furthermore, we explore the utility of ZnP-CTF for gas chromatographic separation of the small hydrocarbons mixture based on their different van der waals interactions and polarizability. More importantly, the fast breakthrough test further proves that the ZnP-CTF-400 and ZnP-CTF-500 can separate the small hydrocarbons under kinetic dynamic conditions. PMID:24018972

  7. Small molecule solution-processed bulk heterojunction solar cells with inverted structure using porphyrin donor

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takaki; Hatano, Junichi; Nakagawa, Takafumi; Yamaguchi, Shigeru; Matsuo, Yutaka

    2013-01-01

    Utilizing tetraethynyl porphyrin derivative (TE-Por) as a small molecule donor material, we fabricated a small molecule solution-processed bulk heterojunction (BHJ) solar cell with inverted structure, which exhibited 1.6% power conversion efficiency (JSC (short-circuit current) = 4.6 mA/cm2, VOC (open-circuit voltage) = 0.90 V, and FF (fill factor) = 0.39) in the device configuration indium tin oxide/TiOx (titanium sub-oxide)/[6,6]-phenyl-C61-butyric acid methyl ester:TE-Por (5:1)/MoOx (molybdenum sub-oxide)/Au under AM1.5 G illumination at 100 mW/cm2. Without encapsulation, the small molecule solution-processed inverted BHJ solar cell also showed remarkable durability to air, where it kept over 73% of its initial power conversion efficiency after storage for 28 days under ambient atmosphere in the dark.

  8. Method for hydroperoxide decomposition using novel porphyrins synthesized from dipyrromethanes and aldehydes

    DOEpatents

    Wijesekera, Tilak; Lyons, James E.; Ellis, Jr., Paul E.

    1998-01-01

    The invention comprises a method for the oxidation of alkanes to alcohols and for decomposition of hydroperoxides to alcohols utilizing new compositions of matter, which are metal complexes of porphyrins. Preferred complexes have hydrogen, haloalkyl or haloaryl groups in meso positions, two of the opposed meso atoms or groups being hydrogen or haloaryl, and two of the opposed meso atoms or groups being hydrogen or haloalkyl, but not all four of the meso atoms or groups being hydrogen. Other preferred complexes are ones in which all four of the meso positions are substituted with haloalkyl groups and the beta positions are substituted with halogen atoms. A new method of synthesizing porphyrinogens is also disclosed.

  9. Method for hydroperoxide decomposition using novel porphyrins synthesized from dipyrromethanes and aldehydes

    DOEpatents

    Wijesekera, T.; Lyons, J.E.; Ellis, P.E. Jr.

    1998-03-03

    The invention comprises a method for the oxidation of alkanes to alcohols and for decomposition of hydroperoxides to alcohols utilizing new compositions of matter, which are metal complexes of porphyrins. Preferred complexes have hydrogen, haloalkyl or haloaryl groups in meso positions, two of the opposed meso atoms or groups being hydrogen or haloaryl, and two of the opposed meso atoms or groups being hydrogen or haloalkyl, but not all four of the meso atoms or groups being hydrogen. Other preferred complexes are ones in which all four of the meso positions are substituted with haloalkyl groups and the beta positions are substituted with halogen atoms. A new method of synthesizing porphyrinogens is also disclosed.

  10. Method for oxidizing alkanes using novel porphyrins synthesized from dipyrromethanes and aldehydes

    DOEpatents

    Wijesekera, Tilak; Lyons, James E.; Ellis, Jr., Paul E.

    1999-01-01

    The invention comprises a method for the oxidation of alkanes to alcohols and for decomposition of hydroperoxides to alcohols utilizing new compositions of matter, which are metal complexes of porphyrins. Preferred complexes have hydrogen, haloalkyl or haloaryl groups in meso positions, two of the opposed meso atoms or groups being hydrogen or haloaryl, and two of the opposed meso atoms or groups being hydrogen or haloalkyl, but not all four of the meso atoms or groups being hydrogen. Other preferred complexes are ones in which all four of the meso positions are substituted with haloalkyl groups and the beta positions are substituted with halogen atoms. A new method of synthesizing porphyrinogens is also disclosed.

  11. Increasing 13C CP-MAS NMR resolution using single crystals: application to model octaethyl porphyrins.

    PubMed

    Dugar, Sneha; Fu, Riqiang; Dalal, Naresh S

    2012-08-02

    Octaethyl porphyrin (OEP) and its Ni and Zn derivatives are considered as model compounds in biochemical, photophysical, and fossil fuel chemistry. They have thus been investigated by high-resolution solid-state (13)C NMR using powders, but peak assignment has been difficult because of large line widths. Arguing that a significant cause of broadening might be the anisotropic bulk magnetic susceptibility, we utilized single crystals in our (13)C cross-polarization magic angle spinning (CP-MAS) measurements and observed a nearly 2-fold line narrowing. This enhanced resolution enabled us to assign chemical shifts to each carbon for all the three compounds. The new assignments are now in agreement with X-ray structural data and allowed us to probe the motional dynamics of the methyl and methylene carbons of the OEP side chains. It is apparent that the use of single crystals in (13)C CP-MAS measurements has a significantly wider impact than previously thought.

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

    PubMed Central

    Li, Xing-Yu; Zhang, Cai-Rong; Wu, You-Zhi; Zhang, Hai-Min; Wang, Wei; Yuan, Li-Hua; Yang, Hua; Liu, Zi-Jiang; Chen, Hong-Shan

    2015-01-01

    Dye sensitizers can significantly affect power conversion efficiency of dye-sensitized solar cells (DSSCs). Porphyrin-based dyes are promising sensitizers due to their performances in DSSCs. Here, based upon a N-fused carbazole-zinc porphyrin-free-base porphyrin triad containing an ethynyl-linkage (coded as DTBC), the novel porphyrin dyes named DTBC-MP and DTBC-TP were designed by varying the porphyrin-free-base units in the π conjugation of DTBC in order to study the effect of porphyrin-free-base in the modification of electronic structures and related properties. The calculated results indicate that, the extension of the conjugate bridge with the porphyrin-free-base unit results in elevation of the highest occupied molecular orbital (HOMO) energies, decrease of the lowest unoccupied molecular orbital (LUMO) energies, reduction of the HOMO-LUMO gap, red-shift of the absorption bands, and enhancement of the absorbance. The free energy changes demonstrate that introducing more porphyrin-free-base units in the conjugate bridge induces a faster rate of electron injection. The transition properties and molecular orbital characters suggest that the different transition properties might lead to a different electron injection mechanism. In terms of electronic structure, absorption spectra, light harvesting capability, and free energy changes, the designed DTBC-TP is a promising candidate dye sensitizer for DSSCs. PMID:26610469

  13. Porphyrin Biosynthesis Control under Water Stress: Sustained Porphyrin Status Correlates with Drought Tolerance in Transgenic Rice1[W][OA

    PubMed Central

    Phung, Thu-Ha; Jung, Ha-il; Park, Joon-Heum; Kim, Jin-Gil; Back, Kyoungwhan; Jung, Sunyo

    2011-01-01

    A controlled flow of porphyrin metabolites is critical for organisms, but little is known about the control of porphyrin biosynthesis under environmental stress. We monitored transgenic rice (Oryza sativa) plants expressing Myxococcus xanthus protoporphyrinogen oxidase (PPO) for their response to drought stress. Transgenic plants showed significantly improved drought tolerance, as indicated by a higher shoot water potential, less oxidative damage, and a more favorable redox balance compared with wild-type plants. Both transgenic and wild-type plants responded to the onset of drought stress, even prior to changes in shoot water potential and oxidative metabolism, by drastically scavenging porphyrin intermediates in leaves, which was crucial for alleviating reactive oxygen species-induced stress. Protoporphyrin IX, protochlorophyllide, magnesium-protoporphyrin IX, and its methyl ester were absent or hardly detected with the intensification of water stress (–3.1 MPa) in the wild type, whereas transgenic plants retained these intermediates to some extent. Additionally, the expression and activity of most enzymes involved in porphyrin biosynthesis, particularly in the chlorophyll branch, were primarily down-regulated under dehydrating conditions, with stronger repression in the wild type than in transgenic plants. There was up-regulation of Glutamate 1-Semialdehyde Aminotransferase, PPO1, and Fe Chelatase2 transcripts in drought-stressed transgenic plants, enabling the transgenic plants to make larger pools of 5-aminolevulinic acid and protoporphyrin IX available for subsequent steps in the heme branch. Overexpression of PPO ultimately protected the transgenic plants from drought-induced cytotoxicity, demonstrating clearly that manipulation of porphyrin biosynthesis can produce drought-tolerant plants. Our results support a possible role for tetrapyrroles in signaling their metabolic state and in plant protection under drought stress conditions. PMID:22021420

  14. The human porphyrin transporter ABCB6 is dispensable for erythropoiesis but responsible for the new blood group system Langereis

    PubMed Central

    Helias, Virginie; Saison, Carole; Ballif, Bryan A.; Peyrard, Thierry; Takahashi, Junko; Takahashi, Hideo; Tanaka, Mitsunobu; Deybach, Jean-Charles; Puy, Hervé; Le Gall, Maude; Sureau, Camille; Pham, Bach-Nga; Le Pennec, Pierre-Yves; Tani, Yoshihiko; Cartron, Jean-Pierre; Arnaud, Lionel

    2013-01-01

    The human ATP-binding cassette (ABC) transporter ABCB6 has been described as a mitochondrial porphyrin transporter essential for heme biosynthesis1, but is also suspected to contribute to anticancer drug resistance2–4, as do other ABC transporters located at the plasma membrane. We identified ABCB6 as the carrier of the blood group antigen Lan on red blood cells, but also at the plasma membrane of hepatocellular carcinoma (HCC) cells, and established that ABCB6 actually encodes a new blood group system (Langereis, Lan). Targeted sequencing of ABCB6 in 12 unrelated individuals of the blood type Lan− identified 10 different ABCB6 null mutations. This is the first report of deficient alleles of this human ABC transporter gene. Surprisingly, Lan− (ABCB6−/−) individuals do not suffer any clinical consequences, albeit their deficiency in ABCB6 may place them at risk when defining drug dosage. PMID:22246506

  15. Excitonic Coupling and Femtosecond Relaxation of Zinc Porphyrin Oligomers Linked with Triazole Bridge: Dynamics and Modeling.

    PubMed

    Bukreev, Alexey; Mikhailov, Konstantin; Shelaev, Ivan; Gostev, Fedor; Polevaya, Yuliya; Tyurin, Vladimir; Beletskaya, Irina; Umansky, Stanislav; Nadtochenko, Victor

    2016-03-31

    The synthesis of new zinc porphyrin oligomers linked by a triazole bridge was carried out via "click" reaction. A split in the porphyrin oligomer B-band was observed. It was considered as evidence of exciton-excitonic coupling. The relaxation of excited states in Q-band porphyrin oligomers was studied by the femtosecond laser spectroscopy technique with a 20 fs pump pulse. The transient oscillations of two B-band excitonic peaks have a π-radian shift. For explanation of the coherent oscillation, a theoretical model was developed. The model considered the combination of the exciton-excitonic coupling between porphyrin rings in dimer and weak exciton-vibronic coupling in one porphyrin ring. By varying the values of the structural parameters of porphyrins (the strength values of this couplings and measure of symmetry breaking), we obtained correspondence between the experimental data (phase shift and amplitudes of the spectrum oscillations) and the predictions of the model developed here.

  16. Two–Photon Oxygen Sensing with Quantum Dot–Porphyrin Conjugates

    PubMed Central

    Lemon, Christopher M.; Karnas, Elizabeth; Bawendi, Moungi G.; Nocera, Daniel G.

    2013-01-01

    Supramolecular assemblies of a quantum dot (QD) associated to palladium(II) porphyrins have been developed to detect oxygen (pO2) in organic solvents. Palladium porphyrins are sensitive in the 0–160 torr range, making them ideal phosphors for in vivo biological oxygen quantification. Porphyrins with meso pyridyl substituents bind to the surface of the QD to produce self–assembled nanosensors. Appreciable overlap between QD emission and porphyrin absorption features results in efficient Förster resonance energy transfer (FRET) for signal transduction in these sensors. The QD serves as a photon antenna, enhancing porphyrin emission under both one– and two–photon excitation, demonstrating that QD–palladium porphyrin conjugates may be used for oxygen sensing over physiological oxygen ranges. PMID:23978247

  17. A search for porphyrin biomarkers in Nonesuch Shale and extraterrestrial samples.

    NASA Technical Reports Server (NTRS)

    Rho, J. H.; Bauman, A. J.; Boettger, H. G.; Yen, T. F.

    1973-01-01

    An organic solvent extract of billion year old Nonesuch Shale was examined for porphyrins by means of fluorometry and high resolution mass spectrometry. It appears to contain at least three or more classes of porphyrins, one similar to tetraphenyl porphin and the others more complex. Many are apparently chelated with copper, nickel, zinc, iron and vanadyl and are highly aromatic. We have also examined the extracts of Apollo 11, 12 and 14 surface fines for porphyrins by spectrophotofluorometry, but we found none.

  18. Zn-containing porphyrin as a biomimetic light-harvesting molecule for biocatalyzed artificial photosynthesis.

    PubMed

    Kim, Jae Hong; Lee, Sahng Ha; Lee, Joon Seok; Lee, Minah; Park, Chan Beum

    2011-10-07

    Among the porphyrin molecules with different metal insertion sites and functional ligands, Zn-porphyrin most efficiently regenerates NADH through photo-induced electron transfer in the presence of [Cp*Rh(bpy)H(2)O](2+), a rhodium-based electron mediator. Photochemical regeneration of NADH by Zn-porphyrin is successfully coupled with redox enzymatic synthesis under dark state conditions. This journal is © The Royal Society of Chemistry 2011

  19. The Determination of Quantum Yield in the Fluoresence Spectra of Porphyrins

    NASA Astrophysics Data System (ADS)

    ćati, Odeta; Kristo, Kejda; Spiro, Marenglen; Xhuvani, Emil; Babani, Fatbardha; Tafa, Dentila

    2010-01-01

    The porphyrins, natural macromolecules, and especially the glycosylated ones, are recently used in the photodynamic therapy of different kinds of tumor cells. The porphyrins are injected through intravenous way in the human body. Under appropriate radiation of tumor zone with light in UV region, oxidation processes of the porphyrins occur through different mechanizms. As a result, inside the tumor, is producing oxygen in singlet state which is lethal for the tumor cells. The spectroscopic study of the porphyrins, both the absorbtion and the fluoresence spectroscopy, reveals some properties of the porphyrins which are ralated with their eventual application in the photodynamic therapy. So, from the value of the quantum yield, which is an important quantity that derives from the measurement of fluoresence of porphyrins, one can judge, through which mechanizm, the oxidation process does occurs. This suggest how the porphyrin should be used in the therapy, as monomers or as aggregates. The porphyrins are sinthetised in the Laboratory of Chemistry of Natural Compaunds, in the University of Limoges. The spectra has been taken by means of a photospectrometer, in the University of Tirana. The fluoresence spectra of the "protected" and "unprotected" porphyrins are studied. The determination of the quantum yield has been done through the comparison of porphyrins spectra, with them of Rhodamine B, which has a large fluoresence, in the same region of spectrum where does occurr the fluoresence of porphyrins. In order to do that, the calculations of the surface under the fluoresence spectra and under the Rhodamine one, is necessary. Also, the extintion of the fluoresence of some "protected" porphyrins, in polar solution, has been detected. These extintion of fluoresence has to do with the formation of agregates, of dimers, which can be confirmed from the absorbtion spectra.

  20. A quest for porphyrins in lunar soil - Samples from Apollo 11, 12 and 14.

    NASA Technical Reports Server (NTRS)

    Hodgson, G. W.; Kvenvolden, K.; Peterson, E.; Ponnamperuma , C.

    1972-01-01

    Analyses for porphyrins in the lunar samples were carried out by extracting the lunar soils as received by organic solvents followed by analytical demetallation using methanesulfonic acid after which free-base porphyrins, if present, were recovered and demonstrably recomplexed with divalent cations. Samples from Apollo 11 showed the presence of fluorescent substances attributed to exhaust from the descent engine. One sample from Apollo 12 showed pigments resembling porphyrins. The Apollo 14 results were negative.

  1. Microscale determination of the spectral characteristics and carbon-isotopic compositions of porphyrins

    NASA Technical Reports Server (NTRS)

    Popp, B. N.; Hayes, J. M.; Boreham, C. J.

    1993-01-01

    Molar extinction coefficients for band III of Ni porphyrins are calculated from results of spectrophotometric and manometric analyses of individual etioporphyrins, DPEP, cyclic, and diDPEP porphyrins known to initially be pure from mass spectrometry, 1H NMR, and analytical HPLC studies. A method for determining carbon-isotopic compositions and purity of micromolar quantities of individual porphyrins using combined spectrophotometric and manometric techniques is presented.

  2. Effect of hypoxia on porphyrin metabolism in bone marrow mesenchymal stem cells.

    PubMed

    Poleshko, A G; Lobanok, E S; Volotovskii, I D

    2014-05-01

    Under hypoxic conditions, aminolevulinic acid-induced accumulation of porphyrin pigments and increase in heme content was observed in bone marrow mesenchymal stem cells. The expression of transferrin receptor CD71 responsible for Fe(2+) transport into the cell was also enhanced. Blockade of porphyrin-transporting protein ABCG2 with fumitremorgin C under conditions of normoxia and hypoxia induced accumulation of porphyrin pigments; in hypoxia, these changes were more pronounced.

  3. Microscale determination of the spectral characteristics and carbon-isotopic compositions of porphyrins

    NASA Technical Reports Server (NTRS)

    Popp, B. N.; Hayes, J. M.; Boreham, C. J.

    1993-01-01

    Molar extinction coefficients for band III of Ni porphyrins are calculated from results of spectrophotometric and manometric analyses of individual etioporphyrins, DPEP, cyclic, and diDPEP porphyrins known to initially be pure from mass spectrometry, 1H NMR, and analytical HPLC studies. A method for determining carbon-isotopic compositions and purity of micromolar quantities of individual porphyrins using combined spectrophotometric and manometric techniques is presented.

  4. Porphyrin-Based Dye-Sensitized Solar Cells (DSSCs): a Review.

    PubMed

    Birel, Özgül; Nadeem, Said; Duman, Hakan

    2017-02-16

    The current review aims to collect short information about photovoltaic performance and structure of porphyrin-based sensitizers used in dye-sensitized solar cells (DSSC). Sensitizer is the key component of the DSSC device. Structure of sensitizer is important to achieve high photovoltaic performance. Porphyrin derivatives are suitable for DSSC applications due to their thermal, electronic and photovoltaic properties. It describes some electrochemical and spectral properties as well as thestructure of porphyrin dyes used in dye based-solar cells.

  5. A search for porphyrin biomarkers in Nonesuch Shale and extraterrestrial samples.

    NASA Technical Reports Server (NTRS)

    Rho, J. H.; Bauman, A. J.; Boettger, H. G.; Yen, T. F.

    1973-01-01

    An organic solvent extract of billion year old Nonesuch Shale was examined for porphyrins by means of fluorometry and high resolution mass spectrometry. It appears to contain at least three or more classes of porphyrins, one similar to tetraphenyl porphin and the others more complex. Many are apparently chelated with copper, nickel, zinc, iron and vanadyl and are highly aromatic. We have also examined the extracts of Apollo 11, 12 and 14 surface fines for porphyrins by spectrophotofluorometry, but we found none.

  6. Molecular Mechanisms of TNFR-associated Factor 6 (TRAF6) Utilization by the Oncogenic Viral Mimic of CD40, Latent Membrane Protein 1 (LMP1)*

    PubMed Central

    Arcipowski, Kelly M.; Stunz, Laura L.; Graham, John P.; Kraus, Zachary J.; Bush, Tony J. Vanden; Bishop, Gail A.

    2011-01-01

    Latent membrane protein 1 (LMP1), encoded by Epstein-Barr virus, is required for EBV-mediated B cell transformation and plays a significant role in the development of posttransplant B cell lymphomas. LMP1 has also been implicated in exacerbation of autoimmune diseases such as systemic lupus erythematosus. LMP1 is a constitutively active functional mimic of the tumor necrosis factor receptor superfamily member CD40, utilizing tumor necrosis factor receptor-associated factor (TRAF) adaptor proteins to induce signaling. However, LMP1-mediated B cell activation is amplified and sustained compared with CD40. We have previously shown that LMP1 and CD40 use TRAFs 1, 2, 3, and 5 differently. TRAF6 is important for CD40 signaling, but the role of TRAF6 in LMP1 signaling in B cells is not clear. Although TRAF6 binds directly to CD40, TRAF6 interaction with LMP1 in B cells has not been characterized. Here we tested the hypothesis that TRAF6 is a critical regulator of LMP1 signaling in B cells, either as part of a receptor-associated complex and/or as a cytoplasmic adaptor protein. Using TRAF6-deficient B cells, we determined that TRAF6 was critical for LMP1-mediated B cell activation. Although CD40-mediated TRAF6-dependent signaling does not require the TRAF6 receptor-binding domain, we found that LMP1 signaling required the presence of this domain. Furthermore, TRAF6 was recruited to the LMP1 signaling complex via the TRAF1/2/3/5 binding site within the cytoplasmic domain of LMP1. PMID:21262968

  7. Photodynamic effects of new silicon phthalocyanines: in vitro studies utilizing rat hepatic microsomes and human erythrocyte ghosts as model membrane sources.

    PubMed

    Zaidi, S I; Agarwal, R; Eichler, G; Rihter, B D; Kenney, M E; Mukhtar, H

    1993-08-01

    Photodynamic therapy (PDT) of cancer is a modality that relies upon the irradiation of tumors with visible light following selective uptake of a photosensitizer by the tumor tissue. There is considerable emphasis to define new photosensitizers suitable for PDT of cancer. In this study we evaluated six phthalocyanines (Pc) for their photodynamic effects utilizing rat hepatic microsomes and human erythrocyte ghosts as model membrane sources. Of the newly synthesized Pc, two showed significant destruction of cytochrome P-450 and monooxygenase activities, and enhancement of lipid peroxidation, when added to microsomal suspension followed by irradiation with approximately 675 nm light. These two Pc named SiPc IV (HOSiPcOSi[CH3]2[CH2]3N[CH3]2) and SiPc V (HOSiPc-OSi[CH3]2[CH2]3N[CH3]3+I-) showed dose-dependent photodestruction of cytochrome P-450 and monooxygenase activities in liver microsomes, and photoenhancement of lipid peroxidation, lipid hydroperoxide formation and lipid fluorescence in microsomes and erythrocyte ghosts. Compared to chloroaluminum phthalocyanine tetrasulfonate, SiPc IV and SiPc V produced far more pronounced photodynamic effects. Sodium azide, histidine, and 2,5-dimethylfuran, the quenchers of singlet oxygen, afforded highly significant protection against SiPc IV- and SiPc V-mediated photodynamic effects. However, to a lesser extent, the quenchers of superoxide anion, hydrogen peroxide and hydroxyl radical also showed some protective effects. These results suggest that SiPc IV and SiPc V may be promising photosensitizers for the PDT of cancer.

  8. Mathematical model to predict skin concentration of drugs: toward utilization of silicone membrane to predict skin concentration of drugs as an animal testing alternative.

    PubMed

    Sugibayashi, Kenji; Todo, Hiroaki; Oshizaka, Takeshi; Owada, Yoko

    2010-01-01

    To calculate the skin concentration of active ingredients in cosmetics and topical pharmaceuticals using silicone membrane permeation. A series of parabens were used as model ingredients. Skin concentration of parabens was calculated using silicone membrane permeability. Their partition coefficient from formulations to the silicone membrane was determined by the membrane permeation profiles, and used to calculate their silicone membrane concentration, under an assumption that the membrane is one homogenous diffusion layer. The same procedure was applied for hairless rat skin. The calculated concentration of parabens in silicone membrane was very close to their observed values. However, the skin concentration calculated by skin permeability was not similar to the observed concentration. Re-calculation was performed under the assumption that the skin consists of two diffusion layers. This modification using permeation data through full-thickness and stripped skin enabled precise prediction of the skin concentration of parabens. In addition, the partition coefficient to the silicone membrane was useful to estimate their skin concentration. Ingredient concentration in skin can be precisely predicted using diffusion equations and partition coefficients through permeation experiments using a silicone membrane. The calculated in-skin concentration is useful for formulation studies of cosmetics and topical pharmaceuticals.

  9. Effect of fatty acids on the complexation of proteins with porphyrins

    NASA Astrophysics Data System (ADS)

    Gyulkhandanyan, Grigor V.

    2011-02-01

    Porphyrins binding and transport to tumor is the one of the central tasks of photodynamic therapy of tumor (PDT). The main carriers of porphyrins (photosensitizers) in the blood are lipoproteins, serum albumin and hemoglobin. In studying the phenomenon of complexation of proteins with ligands must take into considering the real conditions that exist in the organism and, in particular, take into considering the presence of fatty acids in blood. Up to date the role of fatty acids (palmitic and stearic) in the binding of porphyrins with proteins not been determined. A key step in solving of these problems is to determine the binding constants of porphyrin-protein pairs and effect of fatty acids on this process. The most direct and sufficiently accurate methods of solving such problems are complementary methods of absorption and fluorescence spectroscopy. The results of spectral studies on the binding of porphyrins to serum albumin and hemoglobin in the presence of fatty acids demonstrated a significant decrease in the degree of binding pair porphyrin-albumin and porphyrin-hemoglobin with increasing concentrations of fatty acids in solution. The results lead to the conclusion that for hemoglobin the presence in a solution of fatty acids on binding to the porphyrins affected more significantly than for serum albumin. Thus, in natural conditions, when in the blood presented fatty acids the preference between hemoglobin and serum albumin in the binding and in the transport of porphyrins should be given to serum albumin.

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

    PubMed

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

    2007-08-01

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

  11. Synthesis and binding properties of arylethyne-linked porphyrin-zinc complexes for organic electronics applications.

    PubMed

    Reainthippayasakul, W; Paosawatyanyong, B; Bhanthumnavin, W

    2013-05-01

    Conjugated meso-alkynyl 5,15-dimesitylporphyrin metal complexes have been synthesized by Sonogashira coupling reaction in good yields. Alkynyl groups were chosen as a link at the meso positions in order to extend the pi-conjugated length of porphyrin rings. These synthesized porphyrin derivatives were characterized by 1H NMR spectroscopy and MALDI-TOF mass spectrometry. Moreover, UV-visible spectroscopy and fluorescence spectroscopy were also used to investigate their photophysical properties. It has been demonstrated that central metal ions as well as meso substituents on porphyrin rings affected the electronic absorption and emission spectra of the compounds. Spectroscopic results revealed that alkyne-linked porphyrin metal complexes showed higher pi-conjugation compared with porphyrin building blocks resulting in red shifts in both absorption and emission spectra. Coordination properties of synthesized porphyrins were preliminarily investigated by UV-visible absorption and fluorescence emission spectroscopic titration with pyridine as axial ligand. The formation of porphyrin-pyridine complexes resulted in significant red shifts in absorption spectra and decrease of fluorescence intensity in emission spectra. Moreover, the 1H NMR titration experiments suggested that central metal ions play an important role to coordinate with pyridine and the coordination of porphyrin zinc(II) complex with pyridine occur in a 1:1 ratio. From these spectroscopic results, alkyne-linked porphyrin metal complexes offer potential applications as materials for optical organic nanosensors.

  12. Cationic pyridinium porphyrins appending different peripheral substituents: Spectroscopic studies on their interactions with bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Zhao, Ping; Huang, Jin-Wang; Ji, Liang-Nian

    2012-03-01

    The interaction of cationic pyridinium porphyrins appending methylpyridyl, hydroxyphenyl, propionoxyphenyl or carboxyphenyl group at meso-20-position of porphyrin core with bovine serum albumin (BSA), was studied by the combination of absorption spectroscopy, surface-enhanced Raman spectroscopy (SERS), circular dichroism (CD) spectroscopy, fluorescence spectroscopy and synchronous spectroscopy. The spectral monitoring results indicate that the studied compounds could bind with the BSA molecule and the calculated binding constants show that the tetracationic porphyrin has higher binding affinity than those tricationic ones. The interactions between porphyrins and BSA employ an electrostatic binding mechanism and there was only one binding site which located on the surface of the protein molecule.

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

    SciTech Connect

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

    1988-01-01

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

  14. Molecular structures of porphyrin-quinone models for electron transfer

    SciTech Connect

    Fajer, J.; Barkigia, K.M.; Melamed, D.; Sweet, R.M.; Kurreck, H.; Gersdorff, J. von; Plato, M.; Rohland, H.C.; Elger, G.; Moebius, K.

    1996-08-15

    Synthetic porphyrin-quinone complexes are commonly used to mimic electron transport in photosynthetic reaction centers and to probe the effects of energetics, distances, and relative orientations on rates of electron transfer between donor-acceptor couples. The structures of two such models have been determined by X-ray diffraction. The redox pairs consist of a zinc porphyrin covalently linked to benzoquinone in cis and trans configurations via a cyclohexanediyl bridge. The crystallographic studies were undertaken to provide a structural foundation for the extensive body of experimental and theoretical results that exists for these compounds in both the ground and photoinduced charge-separated states. The results validate conclusions reached from theoretical calculations, EPR and two-dimensional NMR results for these states. 15 refs., 6 figs., 2 tabs.

  15. (Metallo)porphyrins for potential materials science applications.

    PubMed

    Smykalla, Lars; Mende, Carola; Fronk, Michael; Siles, Pablo F; Hietschold, Michael; Salvan, Georgeta; Zahn, Dietrich R T; Schmidt, Oliver G; Rüffer, Tobias; Lang, Heinrich

    2017-01-01

    The bottom-up approach to replace existing devices by molecular-based systems is a subject that attracts permanently increasing interest. Molecular-based devices offer not only to miniaturize the device further, but also to benefit from advanced functionalities of deposited molecules. Furthermore, the molecules itself can be tailored to allow via their self-assembly the potential fabrication of devices with an application potential, which is still unforeseeable at this time. Herein, we review efforts to use discrete (metallo)porphyrins for the formation of (sub)monolayers by surface-confined polymerization, of monolayers formed by supramolecular recognition and of thin films formed by sublimation techniques. Selected physical properties of these systems are reported as well. The application potential of those ensembles of (metallo)porphyrins in materials science is discussed.

  16. Porphyrins as Photoredox Catalysts: Experimental and Theoretical Studies.

    PubMed

    Rybicka-Jasińska, Katarzyna; Shan, Wenqian; Zawada, Katarzyna; Kadish, Karl M; Gryko, Dorota

    2016-11-30

    Metalloporphyrins not only are vital in biological systems but also are valuable catalysts in organic synthesis. On the other hand, catalytic properties of free base porphyrins have been less explored. They are mostly known as efficient photosensitizers for the generation of singlet oxygen via photoinduced energy transfer processes, but under light irradiation, they can also participate in electron transfer processes. Indeed, we have found that free base tetraphenylporphyrin (H2TPP) is an efficient photoredox catalyst for the reaction of aldehydes with diazo compounds leading to α-alkylated derivatives. The performance of a porphyrin catalyst can be optimized by tailoring various substituents at the periphery of the macrocycle at both the β and meso positions. This allows for the fine tuning of their optical and electrochemical properties and hence their catalytic activity.

  17. (Metallo)porphyrins for potential materials science applications

    PubMed Central

    Smykalla, Lars; Mende, Carola; Fronk, Michael; Siles, Pablo F; Hietschold, Michael; Salvan, Georgeta; Zahn, Dietrich R T; Schmidt, Oliver G

    2017-01-01

    The bottom-up approach to replace existing devices by molecular-based systems is a subject that attracts permanently increasing interest. Molecular-based devices offer not only to miniaturize the device further, but also to benefit from advanced functionalities of deposited molecules. Furthermore, the molecules itself can be tailored to allow via their self-assembly the potential fabrication of devices with an application potential, which is still unforeseeable at this time. Herein, we review efforts to use discrete (metallo)porphyrins for the formation of (sub)monolayers by surface-confined polymerization, of monolayers formed by supramolecular recognition and of thin films formed by sublimation techniques. Selected physical properties of these systems are reported as well. The application potential of those ensembles of (metallo)porphyrins in materials science is discussed. PMID:28904840

  18. Spatially resolved micro-photoluminescence imaging of porphyrin single crystals

    NASA Astrophysics Data System (ADS)

    Marin, Dawn M.; Castaneda, Jose; Kaushal, Meesha; Kaouk, Ghallia; Jones, Daniel S.; Walter, Michael G.

    2016-08-01

    We describe the collection of both time-resolved and steady-state micro-photoluminescence data from solution-grown single crystals of 5,15-bis(4-carbomethoxyphenyl)porphyrin (BCM2PP). Linking molecular orientation and structure with excited-state dynamics is crucial for engineering efficient organic solar cells, light-emitting diodes, and related molecular electronics. Photoluminescence features of single porphyrin crystals were imaged using a laser scanning confocal microscope equipped with time-correlated single photon counting (TCSPC). We show enhanced exciton lifetimes (τs1 = 2.6 ns) and stronger steady-state emission in crystalline BCM2PP samples relative to semicrystalline thin films (τs1 = 1.8 ns).

  19. Synthesis and Characterization of a New Perhalogenated Porphyrin

    SciTech Connect

    Jia, Songling; Medforth, Craig J.; Nelson, Nora Y.; Nurco, Daniel J.; Shelnutt, John; Smith, Kevin M.

    1999-05-19

    The first synthesis of an octahalotetraalkylporphyrin [2,3,7,8,12,13,17,18 -octabromo-5,10,15,20- tetrakis(trifluoromethyl)porphinato nickel(II)] is reported; this perhalogenated porphyrin has several novel properties including a very nonplanar ruffled structure with an unusually short Ni- N distance, an extremely red-shifted optical spectrum, and hindered rotation of the trifluoromethyl groups ({Delta}G278K =47 kJ mol-1).

  20. Potential use of radiolabelled porphyrins for tumor scanning

    SciTech Connect

    Thaller, R.A.; Lyster, D.M.; Dolphin, D.

    1983-01-01

    Fe-TMPI, Fe-TCP and protohemins showed high initial uptake using tissue culture techniques with mouse tumor cells (P815). However, the tumor uptake in the in vivo model was poor. Of the radionuclides investigated, iron labelled to TMPI demonstrated the best uptake by tumor in vitro. As has been previously demonstrated, the unnatural meso-arylporphyrin derivatives showed better uptake than did naturally occurring porphyrins and their derivatives.

  1. Porphyrin-based Nanostructure-Dependent Photodynamic and Photothermal Therapies

    NASA Astrophysics Data System (ADS)

    Jin, Cheng S.

    This thesis presents the investigation of nanostructure-dependent phototherapy. We reviewed the liposomal structures for delivery of photosensitizers, and introduced a novel class of phototransducing liposomes called "porphysomes". Porphysomes are self-assembled from high packing density of pyropheophorbide alpha-conjugated phospholipids, resulting in extreme self-quenching of porphyrin fluorescence and comparable optical absorption to gold nanoparticles for high photothermal efficiency. We demonstrated this self-assembly of porphyrin-lipid conjugates converts a singlet oxygen generating mechanism (photodynamic therapy PDT activity) of porphyrin to photothermal mechanism (photothermal therapy PTT activity). The efficacy of porphysome-enhanced PTT was then evaluated on two pre-clinical animal models. We validated porphysome-enabled focal PTT to treat orthotopic prostate cancer using MRI-guided focal laser placement to closely mimic the current clinic procedure. Furthermore, porphysome-enabled fluorescence-guided transbronchial PTT of lung cancer was demonstrated in rabbit orthotopic lung cancer models, which led to the development of an ultra-minimally invasive therapy for early-stage peripheral lung cancer. On the other hand, the nanostructure-mediated conversion of PDT to PTT can be switched back by nanoparticle dissociation. By incorporating folate-conjugated phospholipids into the formulation, porphysomes were internalized into cells rapidly via folate receptor-mediated endocytosis and resulted in efficient disruption of nanostructures, which turned back on the photodynamic activity of densely packed porphyrins, making a closed loop of conversion between PDT and PTT. The multimodal imaging and therapeutic features of porphysome make it ideal for future personalized cancer treatments.

  2. A single crystalline porphyrinic titanium metal–organic framework

    SciTech Connect

    Yuan, Shuai; Liu, Tian -Fu; Feng, Dawei; Tian, Jian; Wang, Kecheng; Qin, Junsheng; Zhang, Qiang; Chen, Ying -Pin; Bosch, Mathieu; Zou, Lanfang; Teat, Simon J.; Dalgarno, Scott J.; Zhou, Hong -Cai

    2015-04-28

    We successfully assembled the photocatalytic titanium-oxo cluster and photosensitizing porphyrinic linker into a metal–organic framework (MOF), namely PCN-22. A preformed titanium-oxo carboxylate cluster is adopted as the starting material to judiciously control the MOF growth process to afford single crystals. This synthetic method is useful to obtain highly crystalline titanium MOFs, which has been a daunting challenge in this field. Moreover, PCN-22 demonstrated permanent porosity and photocatalytic activities toward alcohol oxidation.

  3. A single crystalline porphyrinic titanium metal–organic framework

    DOE PAGES

    Yuan, Shuai; Liu, Tian -Fu; Feng, Dawei; ...

    2015-04-28

    We successfully assembled the photocatalytic titanium-oxo cluster and photosensitizing porphyrinic linker into a metal–organic framework (MOF), namely PCN-22. A preformed titanium-oxo carboxylate cluster is adopted as the starting material to judiciously control the MOF growth process to afford single crystals. This synthetic method is useful to obtain highly crystalline titanium MOFs, which has been a daunting challenge in this field. Moreover, PCN-22 demonstrated permanent porosity and photocatalytic activities toward alcohol oxidation.

  4. Differing HOMO and LUMO mediated conduction in a porphyrin nanorod.

    PubMed

    Friesen, Benjamin A; Wiggins, Bryan; McHale, Jeanne L; Mazur, Ursula; Hipps, K W

    2010-06-30

    In this communication we provide the first UHV-STM images and STM-based current-voltage (I-V) and orbital mediated tunneling spectroscopy (OMTS) data on a self-assembled porphyrin nanostructure at the single structure level. We will show that transverse conductivity over distances less than 10 nm can occur by barrier type tunneling but that long distance conduction solely occurs through the LUMO band. These nanorods are very highly rectifying.

  5. Galactodendritic porphyrinic conjugates as new biomimetic catalysts for oxidation reactions.

    PubMed

    Castro, Kelly A D F; Silva, Sandrina; Pereira, Patrícia M R; Simões, Mário M Q; Neves, Maria da Graça P M S; Cavaleiro, José A S; Wypych, Fernando; Tomé, João P C; Nakagaki, Shirley

    2015-05-04

    This work employed [5,10,15,20-tetrakis(pentafluorophenyl)porphyrin] ([H2(TPPF20)], H2P1) as the platform to prepare a tetrasubstituted galactodendritic conjugate porphyrin (H2P3). After metalation with excess copper(II) acetate, H2P3 afforded a new solid porphyrin material, Cu4CuP3S. This work also assessed the ability of the copper(II) complex (CuP3) of H2P3 to coordinate with zinc(II) acetate, to yield the new material Zn4CuP3S. UV-visible, Fourier transform infrared, and electron paramagnetic resonance spectroscopies aided full characterization of the synthesized solids. (Z)-Cyclooctene epoxidation under heterogeneous conditions helped to evaluate the catalytic activity of Cu4CuP3S and Zn4CuP3S. The efficiency of Cu4CuP3S in the oxidation of another organic substrate, catechol, was also investigated. According to the results obtained in the heterogeneous process, Cu4CuP3S mimicked the activity of cytochrome P-450 and catecholase. In addition, Cu4CuP3S was reusable after recovery and reactivation. The data obtained herein were compared with the results achieved for the copper complex (CuP1) of [H2(TPPF20)] and for CuP3 under homogeneous conditions.

  6. Active-Site-Accessible, Porphyrinic Metal;#8722;Organic Framework Materials

    SciTech Connect

    Farha, Omar K.; Shultz, Abraham M.; Sarjeant, Amy A.; Nguyen, SonBinh T.; Hupp, Joseph T.

    2012-02-06

    On account of their structural similarity to cofactors found in many metallo-enzymes, metalloporphyrins are obvious potential building blocks for catalytically active, metal-organic framework (MOF) materials. While numerous porphyrin-based MOFs have already been described, versions featuring highly accessible active sites and permanent microporosity are remarkably scarce. Indeed, of the more than 70 previously reported porphyrinic MOFs, only one has been shown to be both permanently microporous and contain internally accessible active sites for chemical catalysis. Attempts to generalize the design approach used in this single successful case have failed. Reported here, however, is the synthesis of an extended family of MOFs that directly incorporate a variety of metalloporphyrins (specifically Al{sup 3+}, Zn{sup 2+}, Pd{sup 2+}, Mn{sup 3+}, and Fe{sup 3+} complexes). These robust porphyrinic materials (RPMs) feature large channels and readily accessible active sites. As an illustrative example, one of the manganese-containing RPMs is shown to be catalytically competent for the oxidation of alkenes and alkanes.

  7. 3D Porphyrin-Based Covalent Organic Frameworks.

    PubMed

    Lin, Guiqing; Ding, Huimin; Chen, Rufan; Peng, Zhengkang; Wang, Baoshan; Wang, Cheng

    2017-06-28

    The design and synthesis of three-dimensional covalent organic frameworks (3D COFs) bearing photoelectric units have been considered as a big challenge. Herein, for the first time, we reported the targeted synthesis of two 3D porphyrin-based COFs (3D-Por-COF and 3D-CuPor-COF), starting from tetrahedral (3D-Td) and square (2D-C4) building blocks connected through [4 + 4] imine condensation reactions. On the basis of structural characterizations, 3D-Por-COF and 3D-CuPor-COF are microporous materials with high surface areas, and are proposed to adopt a 2-fold interpenetrated pts topology with Pmc21 space group. Interestingly, both 3D COFs are photosensitive and can be used as heterogeneous catalyst for generating singlet oxygen under photoirradiation. However, 3D-Por-COF shows enhanced photocatalytic activity compared with 3D-CuPor-COF, indicating the properties of 3D porphyrin-based COFs can be tuned by metalation of porphyrin rings. The results reported here will greatly inspire us to design and synthesize 3D COFs bearing other metalloporphyrins for interesting applications (e.g., catalysis) in the future.

  8. J-aggregation in porphyrin nanoparticles induced by diphenylalanine

    NASA Astrophysics Data System (ADS)

    Li, Fengqing; Liu, Dongzhi; Wang, Tianyang; Hu, Jianxin; Meng, Fancui; Sun, Haiya; Shang, Zhi; Li, Pingan; Feng, Wenhui; Li, Wei; Zhou, Xueqin

    2017-08-01

    In this report, L-diphenylalanine-decorated tetraphenylporphyrin (TPPtFFC) was synthesized and self-assembled into regular nano-architechtures. The morphology of the assemblies varied with the concentration of TPPtFFC. The absorption spectra of the nanoparticles show the Soret band merges with the Q bands and redistributes with great red-shift, indicative of the formation of J-aggregates of the porphyrin molecules. The fluorescence emission of the nanoparticles is merged and red-shifted to near-infrared region. Studies of absorption and fluorescence spectra reveal an indispensible role of diphenylalanine group in the formation of J-aggregates. The Raman spectra disclose that diprotonation of the porphyrin core contributes to delocalized coherent excited states in the nanoparticles. The positive cotton effect in circular dichroism spectra corresponding to the Soret band of TPPtFFC in solution confirms the formation of J-aggregates with right-handed chirality of the dipole moment. This report will shed light on the rational design of porphyrin-peptide conjugates to mimic naturally light-harvesting complexes.

  9. [Bulk heterojunction solar cell based on porphyrin compounds].

    PubMed

    Zhang, Tian-hui; Zhao, Su-ling; Piao, Ling-yu; Xu, Zheng; Kong, Chao

    2012-01-01

    Three kinds of porphyrins which can abbreviate as TPP, TPPCu and TMPPFeCl were synthesized by one-step method with mixed solvents. Then these porphyrin materials were used as donors to fabricate organic solar cells with PCBM as accepter by the solution processing of spin-coating method. The structure is ITO/porphyrin : PCBM/Al. The photovoltaic characterizations of these devices were investigated. The device based on TPP : PCBM shows the best performance with an open circuit voltage (V(OC)) of 0.52 V, a short circuit current (J(SC)) of 0.98 mA x cm(-2), and fill factor (FF) of 30.1%. Then the influence of different weight ratio of TPP : PCBM was researched. The best weight ratio of TPP : PCBM is 1 : 1. Increasing or decreasing the quatity of TPP would make J(SC) and V(OC) of the device deterioration and have little effect on the FF.

  10. Cationic porphyrin derivatives for application in photodynamic therapy of cancer

    NASA Astrophysics Data System (ADS)

    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.

  11. [Investigation on optical limiting performance in solution of cobalt porphyrin].

    PubMed

    Yin, Yan-feng; Wang, Xiu-ru; Ou, Hui-ling; Han, Jun-he; Mo, Yu-jun

    2004-01-01

    The nonlinear optical effects of cobalt porphyrin have been investigated with three CW laser lines of 457.9, 488 and 514.5 nm, respectively. Three curves with peak followed by valley using the single beam z-scan technique were obtained. According to M Sheik-bahae's theory the sample has a negative nonlinear refractive index, that is, there is a thermal self-defocusing effect. Three curves of transmittance show a decrease with the increase in the incident laser power, which means that the sample has reverse saturated absorption property under the three laser wavelengths. It's well known that both thermal self-defocusing effect and reverse saturated absorption can lead to optical limiting. It was found that cobalt porphyrin has the optical limiting effect under those wavelengths, and that the critical value of optical limiting decreases with the decrease in laser wavelength. Furthermore, the effect of optical limiting is very good and the critical value is very low, so it's a new optical limiting material with a great potential application value. For that, it is possible to use the co-operation of both effects from cobalt porphyrin to produce a new kind of optical limiting device.

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  13. Porphyrins as Molecular Electronic Components of Functional Devices

    PubMed Central

    Jurow, Matthew; Schuckman, Amanda E.; Batteas, James D.; Drain, Charles Michael

    2010-01-01

    The proposal that molecules can perform electronic functions in devices such as diodes, rectifiers, wires, capacitors, or serve as functional materials for electronic or magnetic memory, has stimulated intense research across physics, chemistry, and engineering for over 35 years. Because biology uses porphyrins and metalloporphyrins as catalysts, small molecule transporters, electrical conduits, and energy transducers in photosynthesis, porphyrins are an obvious class of molecules to investigate for molecular electronic functions. Of the numerous kinds of molecules under investigation for molecular electronics applications, porphyrins and their related macrocycles are of particular interest because they are robust and their electronic properties can be tuned by chelation of a metal ion and substitution on the macrocycle. The other porphyrinoids have equally variable and adjustable photophysical properties, thus photonic applications are potentiated. At least in the near term, realistic architectures for molecular electronics will require self-organization or nanoprinting on surfaces. This review concentrates on self-organized porphyrinoids as components of working electronic devices on electronically active substrates with particular emphasis on the effect of surface, molecular design, molecular orientation and matrix on the detailed electronic properties of single molecules. PMID:20936084

  14. Characterization of the Plesiomonas shigelloides Genes Encoding the Heme Iron Utilization System

    PubMed Central

    Henderson, D. P.; Wyckoff, E. E.; Rashidi, C. E.; Verlei, H.; Oldham, A. L.

    2001-01-01

    Plesiomonas shigelloides is a gram-negative pathogen which can utilize heme as an iron source. In previous work, P. shigelloides genes which permitted heme iron utilization in a laboratory strain of Escherichia coli were isolated. In the present study, the cloned P. shigelloides sequences were found to encode ten potential heme utilization proteins: HugA, the putative heme receptor; TonB and ExbBD; HugB, the putative periplasmic binding protein; HugCD, the putative inner membrane permease; and the proteins HugW, HugX, and HugZ. Three of the genes, hugA, hugZ, and tonB, contain a Fur box in their putative promoters, indicating that the genes may be iron regulated. When the P. shigelloides genes were tested in E. coli K-12 or in a heme iron utilization mutant of P. shigelloides, hugA, the TonB system genes, and hugW, hugX, or hugZ were required for heme iron utilization. When the genes were tested in a hemA entB mutant of E. coli, hugWXZ were not required for utilization of heme as a porphyrin source, but their absence resulted in heme toxicity when the strains were grown in media containing heme as an iron source. hugA could replace the Vibrio cholerae hutA in a heme iron utilization assay, and V. cholerae hutA could complement a P. shigelloides heme utilization mutant, suggesting that HugA is the heme receptor. Our analyses of the TonB system of P. shigelloides indicated that it could function in tonB mutants of both E. coli and V. cholerae and that it was similar to the V. cholerae TonB1 system in the amino acid sequence of the proteins and in the ability of the system to function in high-salt medium. PMID:11292789

  15. Thermodynamic analysis of porphyrin binding to Momordica charantia (bitter gourd) lectin.

    PubMed

    Sultan, Nabil A M; Maiya, Bhaskar G; Swamy, Musti J

    2004-08-01

    Owing to the use of porphyrins in photodynamic therapy for the treatment of malignant tumors, and the preferential interaction of lectins with tumor cells, studies on lectin-porphyrin interaction are of significant interest. In this study, the interaction of several free-base and metalloporphyrins with Momordica charantia (bitter gourd) lectin (MCL) was investigated by absorption spectroscopy. Difference absorption spectra revealed that significant changes occur in the Soret band region of the porphyrins on binding to MCL. These changes were monitored to obtain association constants (Ka) and stoichiometry of binding. The tetrameric MCL binds four porphyrin molecules, and the stoichiometry was unaffected by the presence of the specific sugar, lactose. In addition, the agglutination activity of MCL was unaffected by the presence of the porphyrins used in this study, clearly indicating that porphyrin and carbohydrate ligands bind at different sites. Both cationic and anionic porphyrins bind to the lectin with comparable affinity (Ka =10(3)-10(5) m(-1)). The thermodynamic parameters associated with the interaction of several porphyrins, obtained from the temperature dependence of the Ka values, were found to be in the range: DeltaH degrees = -98.1 to -54.4 kJ.mol(-1) and DeltaS degrees =-243.9 to -90.8 J.mol(-1).K(-1). These results indicate that porphyrin binding to MCL is governed by enthalpic forces and that the contribution from binding entropy is negative. Enthalpy-entropy compensation was observed in the interaction of different porphyrins with MCL, underscoring the role of water structure in the overall binding process. Analysis of CD spectra of MCL indicates that this protein contains about 13%alpha-helix, 36%beta-sheet, 21%beta-turn, and the rest unordered structures. Binding of porphyrins does not significantly alter the secondary and tertiary structures of MCL.

  16. Construction of surfactant-like tetra-tail amphiphilic peptide with RGD ligand for encapsulation of porphyrin for photodynamic therapy.

    PubMed

    Chen, Jing-Xiao; Wang, Hui-Yuan; Li, Cao; Han, Kai; Zhang, Xian-Zheng; Zhuo, Ren-Xi

    2011-02-01

    A surfactant-like tetra-tail amphiphilic peptide, [(C(18))(2)K](2)KR(8)GRGDS was designed and synthesized for targeted drug delivery. The resulting peptide-amphiphile, consisting of four hydrophobic aliphatic tails and a hydrophilic peptide head group, was able to self-assemble into nanosized micelles in aqueous medium at low concentration. Ibuprofen and doxorubicin (DOX) was loaded into peptide micelles as model hydrophobic drugs respectively, and the sustained release behavior was observed. Due to the incorporation of targeted arginine-glycine-aspartic acid (RGD) sequences and cell penetrating peptide (CPP) residue octaarginine (R(8)), the micelles could be recognized specifically by cancer cells, as well as transport through the cell membrane efficiently. The observation of laser-scanning confocal microscopy confirmed effective cellular uptaking of porphyrin-loaded peptide micelles. Furthermore, the porphyrin-loaded micelles exhibited low dark toxicity and high phototoxicity against cancer cells, indicating the powerful potential for effective photodynamic therapy. Combined with the low cytotoxicity of the peptide against both HeLa and 293T cell lines, the surfactant-like peptide developed in this study may be promising in clinical application for targeted drug delivery. 2010 Elsevier Ltd. All rights reserved.

  17. Efficient sensitization of dye-sensitized solar cells by novel triazine-bridged porphyrin-porphyrin dyads.

    PubMed

    Zervaki, Galateia E; Roy, Mahesh S; Panda, Manas K; Angaridis, Panagiotis A; Chrissos, Emmanouel; Sharma, Ganesh D; Coutsolelos, Athanassios G

    2013-09-03

    Two novel porphyrin-porphyrin dyads, the symmetrical Zn[Porph]-Zn[Porph] (2) and unsymmetrical Zn[Porph]-H2[Porph] (4), where Zn[Porph] and H2[Porph] are the metalated and free-base forms of 5-(4-aminophenyl)-10,15,20-triphenylporphyrin, respectively, in which two porphyrin units are covalently bridged by 1,3,5-triazine, have been synthesized via the stepwise amination of cyanuric chloride. The dyads are also functionalized by a terminal carboxylic acid group of a glycine moiety attached to the triazine group. Photophysical measurements of 2 and 4 showed broaden and strengthened absorptions in their visible spectra, while electrochemistry experiments and density functional theory calculations revealed negligible interaction between the two porphyrin units in their ground states but appropriate frontier orbital energy levels for use in dye-sensitized solar cells (DSSCs). The 2- and 4-based solar cells have been fabricated and found to exhibit power conversion efficiencies (PCEs) of 3.61% and 4.46%, respectively (under an illumination intensity of 100 mW/cm(2) with TiO2 films of 10 μm thickness). The higher PCE value of the 4-based DSSC, as revealed by photovoltaic measurements (J-V curves) and incident photon-to-current conversion efficiency (IPCE) spectra of the two cells, is attributed to its enhanced short-circuit current (J(sc)) under illumination, high open-circuit voltage (V(oc)), and fill factor (FF) values. Electrochemical impedance spectra demonstrated shorter electron-transport time (τd), longer electron lifetime (τe), and high charge recombination resistance for the 4-based cell, as well as larger dye loading onto TiO2.

  18. Diagnostic Utility of Increased STIR Signal in the Posterior Atlanto-Occipital and Atlantoaxial Membrane Complex on MRI in Acute C1-C2 Fracture.

    PubMed

    Chang, Y-M; Kim, G; Peri, N; Papavassiliou, E; Rojas, R; Bhadelia, R A

    2017-09-01

    Acute C1-C2 fractures are difficult to detect on MR imaging due to a paucity of associated bone marrow edema. The purpose of this study was to determine the diagnostic utility of increased STIR signal in the posterior atlanto-occipital and atlantoaxial membrane complex (PAOAAM) in the detection of acute C1-C2 fractures on MR imaging. Eighty-seven patients with C1-C2 fractures, 87 with no fractures, and 87 with other cervical fractures with acute injury who had both CT and MR imaging within 24 hours were included. All MR images were reviewed by 2 neuroradiologists for the presence of increased STIR signal in the PAOAAM and interspinous ligaments at other cervical levels. Sensitivity and specificity of increased signal within the PAOAAM for the presence of a C1-C2 fracture were assessed. Increased PAOAAM STIR signal was seen in 81/87 patients with C1-C2 fractures, 6/87 patients with no fractures, and 51/87 patients with other cervical fractures with 93.1% sensitivity versus those with no fractures, other cervical fractures, and all controls. Specificity was 93.1% versus those with no fractures, 41.4% versus those with other cervical fractures, and 67.2% versus all controls for the detection of acute C1-C2 fractures. Isolated increased PAOAAM STIR signal without increased signal in other cervical interspinous ligaments showed 89.7% sensitivity versus all controls. Specificity was 95.3% versus those with no fractures, 83.7% versus those with other cervical fractures, and 91.4% versus all controls. Increased PAOAAM signal on STIR is a highly sensitive indicator of an acute C1-C2 fracture on MR imaging. Furthermore, increased PAOAAM STIR signal as an isolated finding is highly specific for the presence of a C1-C2 fracture, making it a useful sign on MR imaging when CT is either unavailable or the findings are equivocal. © 2017 by American Journal of Neuroradiology.

  19. Selective four electron reduction of O2 by an iron porphyrin electrocatalyst under fast and slow electron fluxes.

    PubMed

    Samanta, Subhra; Sengupta, Kushal; Mittra, Kaustuv; Bandyopadhyay, Sabyasachi; Dey, Abhishek

    2012-08-07

    An iron porphyrin catalyst with four electron donor groups is reported. The porphyrin ligand bears a distal hydrogen bonding pocket which inverts the normal axial ligand binding selectivity exhibited by porphyrins bearing sterically crowded distal structures. This catalyst specifically reduces O(2) by four electrons under both fast and slow electron fluxes at pH 7.

  20. Liquid chromatography of urinary porphyrins for the biological monitoring of occupational exposure to porphyrinogenic substances

    SciTech Connect

    Colombi, A.; Maroni, M.; Ferioli, A.; Valla, C.; Coletti, G.; Foa, V.

    1983-01-01

    Very sensitive and precise analytical methods for measuring total porphyrin excretion and the relative amounts of different porphyrins in urine are required in order to monitor the biological effects of porphyrinogenic substances in workers and the general population. Many analytical steps of a HPLC method for measuring porphyrins as methyl esters in urine have been perfected. Sensitivity is 0.1 microgram/1 for each type of porphyrin, and average recovery is 92% in the range of 50-450 micrograms/liter porphyrins. The coefficient of variation is 3.4% within a series and 12.5% between series. Chemical oxidation before analysis and appropriate storing of the samples are the key points in achieving high quality results. The urinary excretion of porphyrins in healthy male workers varies within the range 21 to 161 micrograms/liter (95% limits of a group of 78 subjects). Concomitant factors, like drug use or liver disorders, were found to alter urinary porphyrin excretion. The proposed method permits the detection of extremely small alterations in porphyrin excretion resulting from occupational exposure to industrial chemicals such as, for example, mild coproporphyrinuria or early stages of chemical porphyria induced by polyhalogenated arylhydrocarbons.

  1. Isoindoline nitroxide-labeled porphyrins as potential fluorescence-suppressed spin probes.

    PubMed

    Liu, F; Zou, T J; Tan, Z L; Chen, S; Wu, Z H; Yan, G P; Zhang, Q; Liang, S C; Yang, J

    2017-02-07

    A series of isoindoline nitroxide-labeled porphyrins were synthesized by the reaction of 5-phenyldipyrromethane and 5-(4'-carboethoxy-methyleneoxyphenyl)dipyrromethane with 5-formyl-1,1,3,3-tetramethylisoindolin-2-yloxyl (FTMIO) using the Lindsey method. The corresponding water-soluble spin-labeled porphyrins were also prepared. Subsequently, these compounds were characterized and their in vitro properties were evaluated. The electrochemical assay demonstrated that these isoindoline nitroxide-labeled porphyrins had similar electrochemical and redox properties to 5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl (CTMIO). The electron paramagnetic resonance test showed that these porphyrins exhibited hyperfine splittings and characteristic spectra of CTMIO with typical nitroxide g-values and nitrogen isotropic hyperfine coupling constants. The in vitro cytotoxicity assay indicated that these porphyrins possessed low cytotoxicity to human renal tubular epithelial 293T cells (normal cells) and human hepatoma HepG2 cells (tumor cells). Fluorescence spectroscopy revealed that free base isoindoline nitroxide-labeled porphyrins exhibited fluorescence suppression characteristic of nitroxide-fluorophore systems. In vitro fluorescene imaging demonstrated that the reduced isoindoline nitroxide-labeled porphyrins eliminated fluorescence suppression and displayed strong red fluorescence imaging in HepG2 cells. Thus these isoindoline nitroxide-labeled porphyrins may be considered potentially as biological spin probes for fluorescence imaging and EPR spectroscopy.

  2. The first porphyrin-subphthalocyaninatoboron(iii)-fused hybrid with unique conformation and intramolecular charge transfer behavior.

    PubMed

    Zhang, Yuehong; Oh, Juwon; Wang, Kang; Shin, Dongju; Zhan, Xiaopeng; Zheng, Yingting; Kim, Dongho; Jiang, Jianzhuang

    2016-08-18

    Porphyrin and subphthalocyaninatoboron(iii) chromophores have been fused through a quinoxaline moiety, resulting in the first porphyrin-subphthalocyaninatoboron(iii)-fused hybrid with intramolecular charge transfer from tetrapyrrole/tripyrrole chromophores to the quinoxaline moiety. The unique plane-bowl molecular structure of this hybrid was revealed based on single crystal X-ray diffraction analysis for the first time.

  3. Effectiveness of porphyrin-like compounds in photodynamic damage of atherosclerotic plaque

    NASA Astrophysics Data System (ADS)

    Zalessky, Viacheslav N.; Bobrov, Vladimir; Michalkin, Igor; Trunov, Vitaliy

    1991-06-01

    Porphyrin-like compounds such as tetra-(4 sulfonatophenyl) porphine (TSPP), chlorin-e6 derivative (CED) and tetrasulfophthalocyanin (TSPC) are photosensitizing agents that absorbed light at 630 nm, 657 nm and 625 nm, respectively, and bind preferentially to atherosclerotic plaque. Porphyrin-treated human cadaveric aorta was compared with untreated aorta using several techniques: the absorptive spectrophotometry which has demonstrated the distinct absorptive peaks at 630 nm, 657 nm, 625 nm in porphyrin-treated plaque which were absent in untreated normal aorta; the fluorescence microscopy, which has shown that the treated atheroma acquired the characteristic fluorescence of porphyrin under ultraviolet light. Because of the porphyrin''s unique property, porphyrin-treated and untreated aorta was exposed to red laser radiation at a wavelength of 632.8 nm. It was found that enhanced photoalteration of porphyrin-treated compared with untreated atheroma. Histologic analysis of the depth of tissue penetration of equal amounts of laser radiation has demonstrated more pronounced photosensitizing effect in TSPC-treated plaque compared with CED-, TSPP-, and untreated plaques. This study demonstrates a potential of tetrasulfophthalocyanin for selective alteration of atheroma by He-Ne laser radiation.

  4. Supramolecular Electronic Interactions in Porphyrin-SWCNT Hybrids through Amidinium-Carboxylate Connectivity.

    PubMed

    Rodríguez-Pérez, Laura; Vela, Sonia; Atienza, Carmen; Martín, Nazario

    2017-09-15

    New supramolecular (metal)porphyrin/SWCNT hybrids have been synthesized through a combination of hydrogen bond and electrostatic interactions. Our experimental findings reveal through different techniques (XPS, TGA, UV-vis, Raman, and TEM) an efficient n-doping of the SWCNT from the electron donor (metal)porphyrin through the efficient and strong amidinium-carboxylate connectivity.

  5. Fusing porphyrins with polycyclic aromatic hydrocarbons and heterocycles for optoelectronic applications

    DOEpatents

    Thompson, Mark E.; Diev, Viacheslav; Hanson, Kenneth; Forrest, Stephen R.

    2015-08-18

    A compound that can be used as a donor material in organic photovoltaic devices comprising a non-activated porphyrin fused with one or more non-activated polycyclic aromatic rings or one or more non-activated heterocyclic rings can be obtained by a thermal fusion process. The compounds can include structures of Formula I: ##STR00001## By heating the reaction mixture of non-activated porphyrins with non-activated polycyclic aromatic rings or heterocyclic rings to a fusion temperature and holding for a predetermined time, fusion of one or more polycyclic rings or heterocyclic rings to the non-activated porphyrin core in meso,.beta. fashion is achieved resulting in hybrid structures containing a distorted porphyrin ring with annulated aromatic rings. The porphyrin core can be olygoporphyrins.

  6. Cooperative self-assembly of porphyrins with polymers possessing bioactive functions.

    PubMed

    Zhao, Lizhi; Qu, Rui; Li, Ang; Ma, Rujiang; Shi, Linqi

    2016-11-15

    Natural porphyrin derivatives possess many interesting functions in biological systems. They are integrated into proteins that are essential for biological activities. Many efforts have been dedicated to mimic the microenvironment and augment the function of porphyrin/protein scaffolds. To achieve such goals, self-assembly has become one of the popular methods to construct porphyrin/protein-mimicking materials owing to its various choices of building blocks and a simple preparation process over chemical modification. Desirable characteristics of building blocks for protein mimicking include high molecular weight, predictable conformations in solution, and appropriate functional residuals. With these aims in mind, polymers are ideal candidates due to their multiple-level hierarchies derived from their chemical and spatial structures. In this review, design strategies for the cooperative self-assembly of porphyrins with polymers and the main efforts towards the implementation of porphyrin/polymer assembly for biomimetic composites with bioactive functions will be addressed.

  7. Out-of-Plane Coordinated Porphyrin Nanotubes with Enhanced Singlet Oxygen Generation Efficiency

    PubMed Central

    Zhao, Qiang; Wang, Yao; Xu, Yanshuang; Yan, Yun; Huang, Jianbin

    2016-01-01

    A supramolecular porphyrin nanotube displaying J-aggregation feature was constructed by out-of-plane coordinated bismuth-porphyrin. Significantly, compared to traditional J-aggregated porphyrin suffering from fluorescence and singlet oxygen quenching, the nanotube exhibits excellent bio-imaging ability and enhanced production efficiency of singlet oxygen. The out-of-plane structure of bismuth to porphyrin makes the aggregation an appropriate material for theranostics. Furthermore, it is also a potential radio-therapeutic drug owing to the presence of radio-active bismuth. Thus, the self-assembly of out-of-plane coordinated porphyrin can be a facile approach toward effective therapy of tumors and other diseases. PMID:27527403

  8. DNA binding and photocleavage properties of a novel cationic porphyrin-anthraquinone hybrid.

    PubMed

    Zhao, Ping; Xu, Lian-Cai; Huang, Jin-Wang; Zheng, Kang-Cheng; Liu, Jie; Yu, Han-Cheng; Ji, Liang-Nian

    2008-04-01

    A novel cationic porphyrin-anthraquinone (Por-AQ) hybrid has been synthesized and characterized. Using the combination of absorption titration, fluorescence spectra, circular dichroism (CD) as well as viscosity measurements, the binding properties of the hybrid to calf thymus (CT) DNA have been investigated compared with its parent porphyrin. The experimental results show that at low [Por]/[DNA] ratios, the parent porphyrin binds to DNA in an intercalative mode while the hybrid binds in a combined mode of outside binding (for porphyrin moiety) and partial intercalation (for anthraquinone). Ethidium bromide (EB) competition experiment determined the binding affinity constants (K(app)) of the compounds for CT DNA. Theoretical calculational results applying the density functional theory (DFT) can explain the different DNA binding behaviors reasonably. (1)O(2) was suggested to be the reactive species responsible for the DNA photocleavage of porphyrin moieties in both two compounds. The wavelength-depending cleavage activities of the compounds were also investigated.

  9. Absorption and fluorescence properties of aryl substituted porphyrins in different media

    NASA Astrophysics Data System (ADS)

    Bozkurt, Serap Seyhan; Merdivan, Melek; Ayata, Sevda

    2010-02-01

    Absorption and fluorescence properties of aryl substituted porphyrins, 5,10,15,20-tetra-4-oxy(aceticacid)phenylporphyrin (TAPP), 5,10,15,20-tetra-(4-phenoxyphenyl) porphyrin (TPPP), 5,10,15,20-tetra-(3-bromo-4-hydroxyphenyl) porphyrin (TBHPP), and 5,10,15,20-tetra-p-chloromethylphenyl porphyrin (CMPP) were investigated. The UV/vis absorption, fluorescence and excited spectra as the fluorescence quantum yields and fluorescence lifetimes for the compounds were measured in organic solvents (chloroform (CHCl 3), tetrahydrofuran (THF)) and immobilized media (PVC film, sol-gel matrix). The fluorescence quantum yields of TAPP and TPPP were higher than the others. The fluorescence lifetimes of all studied porphyrin derivates were found to be fifty percent lower and their fluorescence intensities were increased fifty percent more in both of immobilized mediums, as compared to organic solvents.

  10. Highly Efficient Cooperative Catalysis by Co(III) (Porphyrin) Pairs in Interpenetrating Metal-Organic Frameworks.

    PubMed

    Lin, Zekai; Zhang, Zhi-Ming; Chen, Yu-Sheng; Lin, Wenbin

    2016-10-24

    A series of porous twofold interpenetrated In-Co(III) (porphyrin) metal-organic frameworks (MOFs) were constructed by in situ metalation of porphyrin bridging ligands and used as efficient cooperative catalysts for the hydration of terminal alkynes. The twofold interpenetrating structure brings adjacent Co(III) (porphyrins) in the two networks parallel to each other with a distance of about 8.8 Å, an ideal distance for the simultaneous activation of both substrates in alkyne hydration reactions. As a result, the In-Co(III) (porphyrin) MOFs exhibit much higher (up to 38 times) catalytic activity than either homogeneous catalysts or MOF controls with isolated Co(III) (porphyrin) centers, thus highlighting the potential application of MOFs in cooperative catalysis. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. The direct synthesis of organic-containing clays and thermal analysis of porphyrin-clay complexes

    SciTech Connect

    Carrado, K.A.; Anderson, K.B.; Grutkoski, P.S.

    1991-01-01

    Synthetic TMA-montmorillonites have now been made in conjunction with synthetic porphyrin-hectorites reported earlier. In order to help progress towards preparation of porphyrin-containing aluminosilicate clays, the thermal stability of porphyrin-clay systems has been examined in detail. Results from TGA and Py-GC-MS indicate that the porphyrin nucleus is extremely stable in the present of clay minerals. Substituents on the nucleus such as pyridinium or anilinium are, on the other hand, slightly destabilized. In addition, the presence of transition metals like Fe(III) in metalloporphyrins appears to catalyze decomposition of the porphyrin nucleus to some degree. The use of Py-GC-MS in conjunction with TGA results greatly clarified the assignment of weight loss peaks. 18 refs., 3 figs.

  12. Kinetic study of delta-Ala induced porphyrins in mice using photoacoustic and fluorescence spectroscopies.

    PubMed

    Stolik, Suren; Tomás, Sergio A; Ramón-Gallegos, Eva; Sánchez, Feliciano

    2002-11-01

    The production of delta-aminolevulinic acid (ALA)-induced porphyrins in mice skin and blood was studied by photoacoustic and fluorescence spectroscopies. Mice were intraperitoneally administered with 30 mg/kg of ALA. The abdominal skin was subsequently excised at specific times within an 8-h interval and its absorption spectrum obtained by photoacoustics. The highest porphyrins concentration in skin, determined from the optical absorption of the Soret band at 410 nm, was found to occur nearly 2 h after ALA administration, but a first peak was also observed at approximately 15 min. Our hypothesis that the first peak represents the porphyrins content in blood vessels within the skin, whereas the second peak corresponds to porphyrins production in skin tissue, was confirmed by analysing the evolution of protoporphyrin IX content in plasma extracted intracardiacally. By finally applying phase resolved photoacoustic spectroscopy, we were able to evaluate the mean depth at which porphyrins are generated.

  13. Characterisation of nanohybrids of porphyrins with metallic and semiconducting carbon nanotubes by EPR and optical spectroscopy.

    PubMed

    Cambré, Sofie; Wenseleers, Wim; Culin, Jelena; Van Doorslaer, Sabine; Fonseca, Antonio; Nagy, Janos B; Goovaerts, Etienne

    2008-09-15

    Single-walled carbon nanotubes (SWCNTs) are noncovalently functionalised with octaethylporphyrins (OEPs) and the resulting nanohybrids are isolated from the free OEPs. Electron paramagnetic resonance (EPR) spectroscopy of cobalt(II)OEP, adsorbed on the nanotube walls by pi-pi-stacking, demonstrates that the CNTs act as electron acceptors. EPR is shown to be very effective in resolving the different interactions for metallic and semiconducting tubes. Moreover, molecular oxygen is shown to bind selectively to nanohybrids with semiconducting tubes. Water solubilisation of the porphyrin/CNT nanohybrids using bile salts, after applying a thorough washing procedure, yields solutions in which at least 99% of the porphyrins are interacting with the CNTs. Due to this purification, we observe, for the first time, the isolated absorption spectrum of the interacting porphyrins, which is strongly red-shifted compared to the free porphyrin absorption. In addition a quasi-complete quenching of the porphyrin fluorescence is also observed.

  14. The chemistry of rhenium and tungsten porphyrin complexes in low oxidation states. Synthesis and characterization of rhenium and tungsten porphyrin dimers containing metal-metal multiple bonds

    SciTech Connect

    Collmann, J.P.; Garner, J.M.; Woo, L.K. )

    1989-10-11

    The coordination chemistry of rhenium and tungsten porphyrin complexes in low oxidation states is presented. W{sup IV}(Por)(Cl){sub 2}, W{sup II}(Por)(H{sub 5}C{sub 6}C{identical to}CC{sub 6}H{sub 5}) and W{sup II}(OEP)(PEt{sub 3}){sub 2} complexes (Por = 5,10,15,20-tetra(4-tolyl)porphyrin (TTP) or 2,3,7,8,12,13,17,18-octaethylporphyrin (OEP) dianions) were found to be similar to the analogous molybdenum porphyrin complexes by spectroscopic and magnetic measurements. UV-visible and vibrational spectroscopies indicate that these oxidations occur at the metal-metal bond rather than the porphyrin ligand.

  15. Ratiometric and colorimetric "naked eye" selective detection of CN(-) ions by electron deficient Ni(II) porphyrins and their reversibility studies.

    PubMed

    Kumar, Ravi; Chaudhri, Nivedita; Sankar, Muniappan

    2015-05-21

    Highly electron deficient β-substituted Ni(II) porphyrins (1-5) were synthesized and utilized as novel sensors for selective rapid visual detection of CN(-) ions. This article describes the single crystal X-ray structures, electronic spectral and electrochemical redox properties of these sensors. The ratiometric and colorimetric responses of these porphyrins were monitored by the change in optical absorption spectra. These sensors were found to be highly selective for cyanide ions with extremely high binding constants (10(16)-10(8) M(-2)) through axial ligation of CN(-) ions and are able to detect <0.11 ppm of CN(-) ions. 1-5 were recovered from 1-5·2CN(-) adducts by acid treatment and reused without loss of sensing ability. CN(-) binding strongly perturbs the redox properties of the parent porphyrin π-system. The applicability of 1-5 as practical visible colorimetric test kits for CN(-) ions in aqueous and non-aqueous media has also been explored. The mode of binding was confirmed by single crystal X-ray, spectroscopic studies and DFT calculations.

  16. Engaging Copper(III) Corrole as an Electron Acceptor: Photoinduced Charge Separation in Zinc Porphyrin-Copper Corrole Donor-Acceptor Conjugates.

    PubMed

    Ngo, Thien H; Zieba, David; Webre, Whitney A; Lim, Gary N; Karr, Paul A; Kord, Scheghajegh; Jin, Shangbin; Ariga, Katsuhiko; Galli, Marzia; Goldup, Steve; Hill, Jonathan P; D'Souza, Francis

    2016-01-22

    An electron-deficient copper(III) corrole was utilized for the construction of donor-acceptor conjugates with zinc(II) porphyrin (ZnP) as a singlet excited state electron donor, and the occurrence of photoinduced charge separation was demonstrated by using transient pump-probe spectroscopic techniques. In these conjugates, the number of copper corrole units was varied from 1 to 2 or 4 units while maintaining a single ZnP entity to observe the effect of corrole multiplicity in facilitating the charge-separation process. The conjugates and control compounds were electrochemically and spectroelectrochemically characterized. Computational studies revealed ground state geometries of the compounds and the electron-deficient nature of the copper(III) corrole. An energy level diagram was established to predict the photochemical events by using optical, emission, electrochemical, and computational data. The occurrence of charge separation from singlet excited zinc porphyrin and charge recombination to yield directly the ground state species were evident from the diagram. Femtosecond transient absorption spectroscopy studies provided spectral evidence of charge separation in the form of the zinc porphyrin radical cation and copper(II) corrole species as products. Rates of charge separation in the conjugates were found to be of the order of 10(10)  s(-1) and increased with increasing multiplicity of copper(III) corrole entities. The present study demonstrates the importance of copper(III) corrole as an electron acceptor in building model photosynthetic systems.

  17. Glaser-mediated synthesis and photophysical characterization of diphenylbutadiyne-linked porphyrin dyads.

    PubMed

    Youngblood, W Justin; Gryko, Daniel T; Lammi, Robin K; Bocian, David F; Holten, Dewey; Lindsey, Jonathan S

    2002-04-05

    The Pd-mediated Glaser coupling of a zinc monoethynyl porphyrin and a magnesium monoethynyl porphyrin affords a mixture of three 4,4'-diphenylbutadiyne-linked dyads comprised of two zinc porphyrins (Zn-pbp-Zn), two magnesium porphyrins (Mg-pbp-Mg), and one metalloporphyrin of each type (Zn-pbp-Mg). The latter is easily isolated due to the greater polarity of the magnesium versus the zinc chelate. Exposure of Zn-pbp-Mg to silica gel results in selective demetalation, affording Zn-pbp-Fb where Fb = free base porphyrin. This synthesis route employs the magnesium porphyrin as a latent form of the Fb porphyrin, thereby avoiding copper insertion during the Glaser reaction, and as a polar entity facilitating separation. The absorption spectrum of Zn-pbp-Mg or Zn-pbp-Fb is the sum of the spectra of the component parts, while in each case the fluorescence spectrum upon illumination of the Zn porphyrin is dominated by emission from the Mg or Fb porphyrin. Time-resolved absorption spectroscopy shows that the energy-transfer rate constants are (11 ps)(-1) and (37 ps)(-1) for Zn-pbp-Mg and Zn-pbp-Fb, respectively, corresponding to energy-transfer quantum yields of 0.995 and 0.983, respectively. The calculated Förster through-space rates are (1900 ps)(-1) and (1100 ps)(-1) for Zn-pbp-Mg and Zn-pbp-Fb, respectively. Accordingly, the through-bond process dominates for both dyads with a through-bond:through-space energy-transfer ratio of > or =97:1. Collectively, the studies show that the 4,4'-diphenylbutadiynyl linker supports fast and efficient energy transfer between Zn and Mg or Fb porphyrins.

  18. Evaluation of urinary porphyrin excretion in neonates born to mothers exposed to airborne hexachlorobenzene.

    PubMed Central

    Ozalla, Dolores; Herrero, Carmen; Ribas-Fitó, Núria; To-Figueras, Jordi; Toll, Agustí; Sala, Maria; Grimalt, Joan; Basagaña, Xavier; Lecha, Màrius; Sunyer, Jordi

    2002-01-01

    The existence of a link between hexachlorobenzene (HCB) and porphyria cutanea tarda has been known for a long time. However, the epidemiologic data on effects on health caused by prenatal exposure have not provided convincing evidence that HCB alters porphyrin metabolism. Our objectives were to analyze urinary porphyrin excretion and HCB in maternal serum and fetal cord blood in neonates born in a village (Flix) near a chlorinated solvent factory, to detect possible adverse effects in urinary porphyrin excretion caused by prenatal exposure, and to assess their relationship with HCB blood levels. We conducted a cross-sectional study in the Porphyria Unit at a tertiary care facility in Barcelona, Spain, and the Pediatric Unit of the Móra d'Ebre Hospital, the reference hospital of the study area. We included in the study all neonates (n = 68) born in Móra d'Ebre Hospital 1997-1999 and their mothers. We obtained 68 urine specimens of singleton neonates on the third day after birth to test for urinary porphyrin excretion. We obtained 52 fetal cord blood and 56 maternal serum samples for HCB analysis. Total urinary porphyrins were quantified using spectrofluorometry. Porphyrin profile was determined by HPLC. Serum HCB was analyzed by gas chromatography coupled with electron capture detection. In total population, median HCB levels were 1.08 ng/mL in cord blood and 3.31 ng/mL in maternal serum. Total urinary porphyrin concentration was 37.87 micromol/mol creatinine. Coproporphyrin I and coproporphyrin III were the major porphyrins excreted. We found no positive relationship between urinary porphyrin excretion and HCB levels. However, we observed an association between maternal smoking and coproporphyrin excretion. Although high environmental levels of HCB are reported in the town of Flix, we found no alteration in urinary porphyrin excretion. PMID:11836151

  19. A micropatterned cell array with an integrated oxygen-sensitive fluorescent membrane.

    PubMed

    Montagne, Kevin; Komori, Kikuo; Yang, Fei; Tatsuma, Tetsu; Fujii, Teruo; Sakai, Yasuyuki

    2009-11-01

    We propose a simple method for producing micropatterned cell spots by photocatalytic lithography on a Pt porphyrin-based oxygen-sensitive polystyrene membrane that enables real-time imaging of oxygen consumption of patterned cell spots with sub-millimetre resolution.

  20. Effects of meso-substituents and core-modification on photophysical and electrochemical properties of porphyrin-ferrocene conjugates

    NASA Astrophysics Data System (ADS)

    Rai, Smita; Gayatri, G.; Narahari Sastry, G.; Ravikanth, M.

    2008-12-01

    The effects of meso-substituents and porphyrin core-modification on electronic communication between ferrocene and porphyrin in covalently linked porphyrin-ferrocene conjugates are described. The electrochemical and photophysical studies indicated that the electronic communication between porphyrin and ferrocene is strong when meso-substituents are five membered aryl groups than six membered aryl groups. This may be traced to the near orthogonal arrangement of porphyrin ring with six membered meso-aryl groups leading to weaker interaction between the porphyrin and ferrocenyl groups in conjugates, while the five membered furyl and thienyl groups are closer to the porphyrin plane than being orthogonal. Molecular orbital studies are performed at semiempirical PM3 and BLYP levels to rationalize the results.

  1. Evaluation of the interplay among the charge of porphyrinic photosensitizers, lipid oxidation and photoinactivation efficiency in Escherichia coli.

    PubMed

    Lopes, Diana; Melo, Tânia; Santos, Nuno; Rosa, Liliana; Alves, Eliana; Clara Gomes, M; Cunha, Ângela; Neves, Maria G P M S; Faustino, Maria A F; Domingues, M Rosário M; Almeida, Adelaide

    2014-12-01

    Photodynamic inactivation (PDI) is a simple and controllable method to destroy microorganisms based on the production of reactive oxygen species (ROS) (e.g., free radicals and singlet oxygen), which irreversibly oxidize microorganism's vital constituents resulting in lethal damage. This process requires the combined action of oxygen, light and a photosensitizer (PS), which absorbs and uses the energy from light to produce ROS. For a better understanding of the photoinactivation process, the knowledge on how some molecular targets are affected by PDI assumes great importance. The aim of this work was to study the relation between the number and position of positive charges on porphyrinic macrocycles and the changes observed on bacterial lipids. For that, five porphyrin derivatives, bearing one to four positive charges, already evaluated as PS on Escherichia coli inactivation, have been tested on lipid extracts from this bacterium, and also on a simple liposome model. The effects were evaluated by the quantification of lipid hydroperoxides and by analysis of the variation of fatty acyl profiles. E. coli suspensions and liposomes were irradiated with white light in the presence of each PS (5.0 μM). Afterwards, total E. coli lipids were extracted and quantified by phosphorus assay. Lipid oxidation on bacteria and on liposomes was quantified by ferrous oxidation in xylenol orange (FOX2 assay) and the analysis of the fatty acid profile was done by gas chromatography (GC). As previously observed for E. coli viability, an overall increase in the lipid hydroperoxides content, depending on the PS charge and on its distribution on the macrocycle, was observed. Analysis of the fatty acid profile has shown a decrease of the unsaturated fatty acids, corroborating the relation between lipid oxidation and PDI efficiency. Bacterial membrane phospholipids are important molecular targets of photoinactivation and the number of charges of the PS molecule, as well as their distribution

  2. Porphyrins and their synthesis from dipyrromethanes and aldehydes

    DOEpatents

    Wijesekera, T.; Lyons, J.E.; Ellis, P.E. Jr.

    1998-06-02

    The invention comprises new compositions of matter, which are iron, manganese, cobalt or ruthenium complexes of porphyrins having hydrogen, haloalkyl or haloaryl groups in meso positions, two of the opposed meso atoms or groups being hydrogen or haloaryl, and two of the opposed meso atoms or groups being hydrogen or haloalkyl, but not all four of the meso atoms or groups being hydrogen. The invention also comprises new compositions of matter in which all four of the meso positions are substituted with haloalkyl groups and the beta positions are substituted with halogen atoms. A new method of synthesizing porphyrinogens is also provided.

  3. Porphyrins and their synthesis from dipyrromethanes and aldehydes

    DOEpatents

    Wijesekera, Tilak; Lyons, James E.; Ellis, Jr., Paul E.

    1998-01-01

    The invention comprises new compositions of matter, which are iron, manganese, cobalt or ruthenium complexes of porphyrins having hydrogen, haloalkyl or haloaryl groups in meso positions, two of the opposed meso atoms or groups being hydrogen or haloaryl, and two of the opposed meso atoms or groups being hydrogen or haloalkyl, but not all four of the meso atoms or groups being hydrogen. The invention also comprises new compositions of matter in which all four of the meso positions are substituted with haloalkyl groups and the beta positions are substituted with halogen atoms. A new method of synthesizing porphyrinogens is also provided.

  4. Self-assembly of a chiral porphyrin at surfaces

    NASA Astrophysics Data System (ADS)

    Iavicoli, Patrizia; Linares, Mathieu; Pérez del Pino, Ángel; Lazzaroni, Roberto; Amabilino, David B.

    2008-10-01

    Evaporation of solutions of a new synthetic tetra meso-amidophenyl-substituted porphyrin derivative on graphite leads to different morphologies at the air-solid interface, whose nature depends on the solvent in which the molecule was dissolved. Fibres-which were shown to be a stable aggregate form of the compound by molecular modelling-are observed by AFM, although they do not seem to have the structure which was predicted. The reason for this situation appears to be the dominance of surface-molecule interactions over those between the molecules themselves. On mica surfaces, dewetting takes place, leading to relatively well-defined monolayer and bilayer domains.

  5. Aggregates of a cationic porphyrin as supramolecular probes for biopolymers.

    PubMed

    Occhiuto, Ilaria Giuseppina; Samperi, Mario; Trapani, Mariachiara; De Luca, Giovanna; Romeo, Andrea; Pasternack, Robert F; Scolaro, Luigi Monsù

    2015-12-01

    The copper(II) derivative of the dicationic trans-bis(N-methylpyridinium-4-yl)diphenylporphyrin (t-CuPagg) forms large fractal aggregates in aqueous solution under moderate ionic strength conditions. A kinetic investigation of the aggregation process allows for a choice of experimental conditions to quickly obtain stable assemblies in solution. These positively charged aggregates are able to interact efficiently with negatively charged chiral species, (including bacterial spores) leading to induced circular dichroism signals in the Soret region of the porphyrin, now acting as a sensitive chiroptical probe.

  6. Manganese Porphyrins Catalyze Selective C-H Bond Halogenations

    SciTech Connect

    Liu, Wei; Groves, John T.

    2010-08-31

    We report a manganese porphyrin mediated aliphatic C-H bond chlorination using sodium hypochlorite as the chlorine source. In the presence of catalytic amounts of phase transfer catalyst and manganese porphyrin Mn(TPP)Cl 1, reaction of sodium hypochlorite with different unactivated alkanes afforded alkyl chlorides as the major products with only trace amounts of oxygenation products. Substrates with strong C-H bonds, such as neopentane (BDE =~100 kcal/mol) can be also chlorinated with moderate yield. Chlorination of a diagnostic substrate, norcarane, afforded rearranged products indicating a long-lived carbon radical intermediate. Moreover, regioselective chlorination was achieved by using a hindered catalyst, Mn(TMP)Cl, 2. Chlorination of trans-decalin with 2 provided 95% selectivity for methylene-chlorinated products as well as a preference for the C2 position. This novel chlorination system was also applied to complex substrates. With 5α-cholestane as the substrate, we observed chlorination only at the C2 and C3 positions in a net 55% yield, corresponding to the least sterically hindered methylene positions in the A-ring. Similarly, chlorination of sclareolide afforded the equatorial C2 chloride in a 42% isolated yield. Regarding the mechanism, reaction of sodium hypochlorite with the MnIII porphyrin is expected to afford a reactive MnV=O complex that abstracts a hydrogen atom from the substrate, resulting in a free alkyl radical and a MnIV—OH complex. We suggest that this carbon radical then reacts with a MnIV—OCl species, providing the alkyl chloride and regenerating the reactive MnV=O complex. The regioselectivity and the preference for CH2 groups can be attributed to nonbonded interactions between the alkyl groups on the substrates and the aryl groups of the manganese porphyrin. The results are indicative of a bent [Mnv=O---H---C] geometry due to the C—H approach to the Mn

  7. ARSENIC DETERMINATION IN SALINE WATERS UTILIZING A TUBULAR MEMBRANE AS A GAS-LIQUID SEPATRATOR FOR HYDRIDE GENERATION INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY

    EPA Science Inventory

    A tubular silicone rubber membrane is evaluated as a gas-liquid separator for the determination of arsenic in saline waters via HG-ICP-MS. The system was optimized in terms of NaBH and HCI concentrations. The intermediate gas and carrier gas were optimized in terms of sensitiity ...

  8. ARSENIC DETERMINATION IN SALINE WATERS UTILIZING A TUBULAR MEMBRANE AS A GAS-LIQUID SEPATRATOR FOR HYDRIDE GENERATION INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY

    EPA Science Inventory

    A tubular silicone rubber membrane is evaluated as a gas-liquid separator for the determination of arsenic in saline waters via HG-ICP-MS. The system was optimized in terms of NaBH and HCI concentrations. The intermediate gas and carrier gas were optimized in terms of sensitiity ...

  9. Enhancement of oxygen reduction reaction activities by Pt nanoclusters decorated on ordered mesoporous porphyrinic carbons

    SciTech Connect

    Sun-Mi Hwang; Choi, YongMan; Kim, Min Gyu; Sohn, Young-Jun; Cheon, Jae Yeong; Joo, Sang Hoon; Yim, Sung-Dae; Kuttiyiel, Kurian A.; Sasaki, Kotaro; Adzic, Radoslav R.; Park, Gu-Gon

    2016-03-08

    The high cost of Pt-based membrane electrode assemblies (MEAs) is a critical hurdle for the commercialization of polymer electrolyte fuel cells (PEFCs). Recently, non-precious metal-based catalysts (NPMCs) have demonstrated much enhanced activity but their oxygen reduction reaction (ORR) activity is still inferior to that of Pt-based catalysts resulting in a much thicker electrode in the MEA. For the reduction of mass transport and ohmic overpotential we adopted a new concept of catalyst that combines an ultra-low amount of Pt nanoclusters with metal–nitrogen (M–Nx) doped ordered mesoporous porphyrinic carbon (FeCo–OMPC(L)). The 5 wt% Pt/FeCo–OMPC(L) showed a 2-fold enhancement in activities compared to a higher loading of Pt. Our experimental results supported by first-principles calculations indicate that a trace amount of Pt nanoclusters on FeCo–OMPC(L) significantly enhances the ORR activity due to their electronic effect as well as geometric effect from the reduced active sites. Finally, in terms of fuel cell commercialization, this class of catalysts is a promising candidate due to the limited use of Pt in the MEA.

  10. Enhancement of oxygen reduction reaction activities by Pt nanoclusters decorated on ordered mesoporous porphyrinic carbons

    DOE PAGES

    Sun-Mi Hwang; Choi, YongMan; Kim, Min Gyu; ...

    2016-03-08

    The high cost of Pt-based membrane electrode assemblies (MEAs) is a critical hurdle for the commercialization of polymer electrolyte fuel cells (PEFCs). Recently, non-precious metal-based catalysts (NPMCs) have demonstrated much enhanced activity but their oxygen reduction reaction (ORR) activity is still inferior to that of Pt-based catalysts resulting in a much thicker electrode in the MEA. For the reduction of mass transport and ohmic overpotential we adopted a new concept of catalyst that combines an ultra-low amount of Pt nanoclusters with metal–nitrogen (M–Nx) doped ordered mesoporous porphyrinic carbon (FeCo–OMPC(L)). The 5 wt% Pt/FeCo–OMPC(L) showed a 2-fold enhancement in activities comparedmore » to a higher loading of Pt. Our experimental results supported by first-principles calculations indicate that a trace amount of Pt nanoclusters on FeCo–OMPC(L) significantly enhances the ORR activity due to their electronic effect as well as geometric effect from the reduced active sites. Finally, in terms of fuel cell commercialization, this class of catalysts is a promising candidate due to the limited use of Pt in the MEA.« less

  11. Conjugated polymer/porphyrin complexes for efficient energy transfer and improving light-activated antibacterial activity.

    PubMed

    Xing, Chengfen; Xu, Qingling; Tang, Hongwei; Liu, Libing; Wang, Shu

    2009-09-16

    With the increasing antibiotic resistance of microorganisms, there is a growing interest in the design and development of new materials that are effective in killing bacteria to replace conventional antibiotics. Herein, a new anionic water-soluble polythiophene (PTP) and a cationic porphyrin (TPPN) are synthesized and characterized. They can form a complex through electrostatic interactions, and efficient energy transfer from PTP to TPPN occurs upon irradiation under white light (400-800 nm). The energy of TPPN transfers to triplet by intersystem crossing, followed by sensitization of oxygen molecule to enhance the efficiency of singlet oxygen generation related to TPPN itself. The positive charges of PTP/TPPN complex promote its adsorption to the negatively charged bacteria membranes of gram-negative Escherichia coli and gram-positive Bacillus subtilis through electrostatic interactions, and the singlet oxygen effectively kills the bacteria. The photosensitized inactivation of bacteria for the PTP/TPPN complex is efficient, and about 70% reduction of bacterial viability is observed after only 5 min of irradiation with white light at a fluence rate of 90 mW x cm(-2) (27 J x cm(-2)). The technique provides a promising application in photodynamic inactivation of bacteria on the basis of enhanced energy transfer offered by light-harvesting conjugated polymers.

  12. Inverted meso-aryl porphyrins with heteroatoms; characterization of thia, selena, and oxa N-confused porphyrins.

    PubMed

    Pushpan, S K; Srinivasan, A; Anand, V R; Chandrashekar, T K; Subramanian, A; Roy, R; Sugiura, K; Sakata, Y

    2001-01-12

    Synthesis and characterization of inverted porphyrins containing S, Se, and O are reported. A simple 3 + 1 MacDonald-type condensation using modified tripyrrane containing the N-confused ring and diols afforded various N-confused porphyrins 6a-f in 19-30% yield. The single-crystal X-ray structure of 6b shows a ruffled conformation with tilt angles of 21.11 degrees and 31.23 degrees for the N-confused ring and the adjacent pyrrole ring III, respectively, revealing its severe nonplanarity. Significant changes in C alpha-C beta, C beta-C beta, and C alpha-X bond lengths are observed in 6b relative to free thiophene and pyrrole, suggesting the altered delocalization pathway in the modified N-confused porphyrins. The two molecules in the unit cell show a cyclophane-type noncovalent dimer with a face to face orientation of two N-confused pyrrole rings as a result of the presence of weak N-H...N and C-H...N intermolecular hydrogen bonds involving pyrrole-NH, the N atom of the N-confused ring, and the C atom of the pyrrole ring. A detailed 1H and 13C NMR study by 1D and 2D methods allowed assignments of all the peaks in the free base and protonated forms. NMR studies reveal the presence of three different tautomeric forms in solution for 6c in CDCl3 at low temperature. UV-visible studies reveal absorption band shifts upon heteroatom substitution, and the magnitudes of these shifts are dependent on the nature of the heteroatom. In all cases both monoprotonated and diprotonated species have been identified, and on addition of acid, the first proton goes to the outer N2 atom of the N-confused ring.

  13. Urinary porphyrins as biomarkers for arsenic exposure among susceptible populations in Guizhou Province, China

    SciTech Connect

    Ng, J.C.; Wang, J.P.; Zheng, B.S.; Zhai, C.; Maddalena, R.; Liu, F.; Moore, M.R.

    2005-08-07

    Coal from some areas in Guizhou Province contains elevated levels of arsenic. This has caused arsenicosis in individuals who use arsenic-contaminated coal for the purposes of heating, cooking and drying of food in poorly ventilated dwellings. The population at risk has been estimated to be approximately 200,000 people. We analyzed the porphyrin excretion profile using a HPLC method in urine samples collected from 113 villagers who lived in Xing Ren district, a coal-borne arsenicosis endemic area and from 30 villagers from Xing Yi where arsenicosis is not prevalent. Urinary porphyrins were higher in the arsenic exposed group than those in the control group. The correlation between urinary arsenic and porphyrin concentrations demonstrated the effect of arsenic on heme biosynthesis resulting in increased porphyrin excretion. Both uroporphyrin and coproporphyrin III showed significant increases in the excretion profile of the younger age ({lt} 20 years) arsenic-exposed group, suggesting that porphyrins could be used as early warning biomarkers of chronic arsenic exposure in humans. Greater increases of urinary arsenic and porphyrins in women, children and older age groups who spend much of their time indoors suggest that they might be at a higher risk. Whether elevated porphyrins could predict adverse health effects associated with both cancer and non-cancer end-points in chronically arsenic-exposed populations need further investigation.

  14. Diketopyrrolopyrrole-porphyrin conjugates as broadly absorbing sensitizers for dye-sensitized solar cells.

    PubMed

    Warnan, Julien; Favereau, Ludovic; Meslin, Frédéric; Severac, Marjorie; Blart, Errol; Pellegrin, Yann; Jacquemin, Denis; Odobel, Fabrice

    2012-08-01

    A series of four new push-pull zinc porphyrin-based dyes was synthesised for hybrid photovoltaic solar cells with a view to enhancing the light-harvesting efficiency at approximately 550 nm with a diketopyrrolopyrrole (DPP) unit. The strength of the donor side of the push-pull porphyrin was tuned by affixing the electron-rich 4,4'-dimethoxydiphenylamine group at the meso position of the macrocycle, and the influence of the distance between the semiconductor surface and the porphyrin chromophore was assessed by introducing different π-conjugated spacers. Charge-transfer transitions over great distances were characterised by electronic absorption spectroscopy and DFT calculations. The absorption and photoactivity spectra of the new bichromophoric dyes spans the whole visible spectrum to the red, implying a better light-harvesting efficiency than regular porphyrin as the absorption spectra of DPP and porphyrin complement one another. Photovoltaic conversion efficiencies accordingly increase from 2.40 to 5.19 %. Interestingly, the best overall efficiency was reached with dye 3, which lacks the powerful donating group in the meso position of the porphyrin core. Optical and electrochemical measurements coupled to time dependent (TD)-DFT calculations give insight into the deleterious effect of the 4,4'-dimethoxydiphenylamine unit on the photovoltaic performances, paving the way towards the design of efficient push-pull porphyrin-based sensitizers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Photochemical generation and kinetic studies of a putative porphyrin-ruthenium(V)-oxo species.

    PubMed

    Zhang, Rui; Vanover, Eric; Luo, Weilong; Newcomb, Martin

    2014-06-21

    Photo-disproportionation of a bis-porphyrin-diruthenium(IV) μ-oxo dimer gave a porphyrin-ruthenium(III) species and a putative porphyrin-ruthenium(V)-oxo species that can be detected and studied in real time via laser flash photolysis methods. As determined by its spectral and kinetic behavior, the same oxo transient was also formed by photolysis of a porphyrin-ruthenium(III) N-oxide adduct. Second-order rate constants for reactions with several substrates at 22 °C were determined; representative values of rate constants were kox = 6.6 × 10(3) M(-1) s(-1) for diphenylmethanol, kox = 2.5 × 10(3) M(-1) s(-1) for styrene, and kox = 1.8 × 10(3) M(-1) s(-1) for cyclohexene. The putative porphyrin-ruthenium(V)-oxo transient reacted 5-6 orders of magnitude faster than the corresponding trans-dioxoruthenium(VI) porphyrins, and the rate constants obtained in this work were similar to those of the corrole-iron(V)-oxo derivative. The high reactivity for the photochemically generated ruthenium-oxo species in comparison to other porphyrin-metal-oxo intermediates suggests that it is a true ruthenium(V)-oxo species.

  16. A sensitive bacterial-growth-based test reveals how intestinal Bacteroides meet their porphyrin requirement.

    PubMed

    Halpern, David; Gruss, Alexandra

    2015-12-29

    Bacteroides sp. are dominant constituents of the human and animal intestinal microbiota require porphyrins (i.e., protoporphyrin IX or iron-charged heme) for normal growth. The highly stimulatory effect of porphyrins on Bacteroides growth lead us to propose their use as a potential determinant of bacterial colonization. However, showing a role for porphryins would require sensitive detection methods that work in complex samples such as feces. We devised a highly sensitive semi-quantitative porphyrin detection method (detection limit 1-4 ng heme or PPIX) that can be used to assay pure or complex biological samples, based on Bacteroides growth stimulation. The test revealed that healthy colonized or non-colonized murine and human hosts provide porphyrins in feces, which stimulate Bacteroides growth. In addition, a common microbiota constituent, Escherichia coli, is shown to be a porphyrin donor, suggesting a novel basis for intestinal bacterial interactions. A highly sensitive method to detect porphyrins based on bacterial growth is devised and is functional in complex biological samples. Host feces, independently of their microbiota, and E. coli, which are present in the intestine, are shown to be porphryin donors. The role of porphyrins as key bioactive molecules can now be assessed for their impact on Bacteroides and other bacterial populations in the gut.

  17. Supramolecular ssDNA templated porphyrin and metalloporphyrin nanoassemblies with tunable helicity.

    PubMed

    Sargsyan, Gevorg; Leonard, Brian M; Kubelka, Jan; Balaz, Milan

    2014-02-10

    Free-base and nickel porphyrin-diaminopurine conjugates were formed by hydrogen-bond directed assembly on single-stranded oligothymidine templates of different lengths into helical multiporphyrin nanoassemblies with highly modular structural and chiroptical properties. Large red-shifts of the Soret band in the UV/Vis spectroscopy confirmed strong electronic coupling among assembled porphyrin-diaminopurine units. Slow annealing rates yielded preferentially right-handed nanostructures, whereas fast annealing yielded left-handed nanostructures. Time-dependent DFT simulations of UV/Vis and CD spectra for model porphyrin clusters templated on the canonical B-DNA and its enantiomeric form, were employed to confirm the origin of observed chiroptical properties and to assign the helicity of porphyrin nanoassemblies. Molar CD and CD anisotropy g factors of dialyzed templated porphyrin nanoassemblies showed very high chiroptical anisotropy. The DNA-templated porphyrin nanoassemblies displayed high thermal and pH stability. The structure and handedness of all assemblies was preserved at temperatures up to +85 °C and pH between 3 and 12. High-resolution transition electron microscopy confirmed formation of DNA-templated nickel(II) porphyrin nanoassemblies and their self-assembly into helical fibrils with micrometer lengths.

  18. Tissue distribution and kinetics of endogenous porphyrins synthesized after topical application of ALA in different vehicles

    PubMed Central

    Casas, A; Fukuda, H; Batlle, A M del C

    1999-01-01

    The use of 5-aminolaevulinic acid (ALA) is gaining increasing attention for photosensitization in photodynamic therapy of superficially localized tumours. The aim of this work was to determine the kinetics of porphyrin generation in tissues after topical application of ALA delivered in different vehicles on the skin overlying the tumour and normal skin of mice. Maximal accumulation was found in tumour 3 h after ALA application in both cream and lotion preparations. Normal and overlying tumour skin tissues showed different kinetic patterns, reflecting histological changes when the latter is invaded by tumour cells. Liver, kidney, spleen and blood porphyrins also raised from basal levels, showing that ALA and/or ALA-induced porphyrins reach all tissues after topical application. During the first 24 h of ALA topical application, precursors and porphyrins are excreted by both urine and faeces. ALA lotion applied on the skin overlying the tumour induced higher accumulation of tumoural porphyrins than cream, and lotion applied on normal skin appeared to be the most efficient upon inducing total body porphyrins. This work has demonstrated the great influence of the formulation of ALA vehicle on penetration through the skin. Knowledge of the kinetics of porphyrin generation after different conditions of ALA application is needed for the optimization of diagnosis and phototherapy in human tumours. © 1999 Cancer Research Campaign PMID:10487606

  19. Porphyrins as excellent dyes for dye-sensitized solar cells: recent developments and insights.

    PubMed

    Higashino, Tomohiro; Imahori, Hiroshi

    2015-01-14

    Dye-sensitized solar cells (DSSCs) have attracted much attention as an alternative to silicon-based solar cells because of their low-cost production and high power conversion efficiency. Among various sensitizers, numerous research activities have been focused on porphyrins due to their strong absorption bands in the visible region, versatile modifications of their core, and facile tuning of the electronic structures. In 2005-2007, Officer and Grätzel et al. had achieved a rapid increase in the power conversion efficiency of porphyrin DSSCs from a few percent to as much as 7%. Encouraged by these pioneering works, further high-performance porphyrin dyes have been developed in the last decade. These studies have provided us profound hints for the rational design of sensitizers toward highly efficient DSSCs. Push-pull structures and/or π-extensions have made porphyrins panchromatic in visible and even near-infrared regions. Consequently, porphyrin sensitizers have exhibited power conversion efficiencies that are comparable to or even higher than those of well-established highly efficient DSSCs based on ruthenium complexes. So far the power conversion efficiency has increased up to ca. 13% by using a push-pull porphyrin with a cobalt-based redox shuttle. In this perspective, we review the recent developments in the synthetic design of porphyrins for highly efficient DSSCs.

  20. Rim2, a pyrimidine nucleotide exchanger, is needed for iron utilization in mitochondria

    PubMed Central

    Yoon, Heeyong; Zhang, Yan; Pain, Jayashree; Lyver, Elise R.; Lesuisse, Emmanuel; Pain, Debkumar; Dancis, Andrew

    2016-01-01

    Mitochondria transport and utilize iron for the synthesis of haem and Fe–S clusters. Although many proteins are known to be involved in these processes, additional proteins are likely to participate. To test this hypothesis, in the present study we used a genetic screen looking for yeast mutants that are synthetically lethal with the mitochondrial iron carriers Mrs3 and Mrs4. Several genes were identified, including an isolate mutated for Yfh1, the yeast frataxin homologue. All such triple mutants were complemented by increased expression of Rim2, another mitochondrial carrier protein. Rim2 overexpression was able to enhance haem and Fe–S cluster synthesis in wild-type or Δmrs3/Δmrs4 backgrounds. Conversely Rim2 depletion impaired haem and Fe–S cluster synthesis in wild-type or Δmrs3/Δmrs4 backgrounds, indicating a unique requirement for this mitochondrial transporter for these processes. Rim2 was previously shown to mediate pyrimidine exchange in and out of vesicles. In the present study we found that isolated mitochondria lacking Rim2 exhibited concordant iron defects and pyrimidine transport defects, although the connection between these two functions is not explained. When organellar membranes were ruptured to bypass iron transport, haem synthesis from added iron and porphyrin was still markedly deficient in Rim2-depleted mitochondrial lysate. The results indicate that Rim2 is a pyrimidine exchanger with an additional unique function in promoting mitochondrial iron utilization. PMID:21777202

  1. Giant Stark effect in double-stranded porphyrin ladder polymers

    NASA Astrophysics Data System (ADS)

    Pramanik, Anup; Kang, Hong Seok

    2011-03-01

    Using the first-principles calculations, we have investigated the stability and the electronic structure of two types of recently synthesized one-dimensional nanoribbons, i.e., double-stranded zinc(II) porphyrin ladder polymer (LADDER) arrays. First, electronic structure calculations were used to show that the LADDER is a semiconductor. Most importantly, the application of a transverse electric field significantly reduces the band gap of the LADDER, ultimately converting the LADDER to a metal at a field strength of 0.1 V/Å. The giant Stark effect in this case is almost as strong as that in boron nitride nanotubes and nanoribbons. In the presence of an electric field, hole conduction and electronic conduction will occur entirely through spatially separated strands, rendering these materials useful for nanoelectronic devices. Second, the substitution of hydrogen atoms in the porphyrin units or that of zinc ions with other kinds of chemical species is found to increase the binding strength of the LADDER and reduce the band gap.

  2. Toxicity of polychlorinated biphenyl with special reference to porphyrin metabolism

    SciTech Connect

    Sano, S.; Kawanishi, S.; Seki, Y.

    1985-02-01

    Oral administration of a commercial PCB mixture to chickens caused a hepatic-type porphyria characterized by hepatic accumulation and urinary excretion of uroporphyrin. To clarify the mechanism of the porphyrinogenic activity of these PCBs, the authors studied the structural requirement of synthetic PCB for porphyrinogenic activities by using the cultured chick embryo liver cells and examined the relationship between induction of delta-aminolevulinic acid (ALA) synthetase and inhibition of uroporphyrinogen decarboxylase. They established that the porphyrinogenic effect of PCBs exhibits a sharply defined structure-activity relationship in that only 3,4,3',4'-tetrachlorobiphenyl and 3,4,5,3',4',5'-hexachlorobiphenyl produced a marked accumulation of uroporphyrin. They also demonstrated that in ALA-supplemented cultures, these same compounds lead to accumulation of a large amount of uroporphyrin III, whereas with other PCBs, which were weak inducers of porphyrin synthesis, the accumulated porphyrin was mostly protoporphyrin. Kinetic studies of the sequential decarboxylation of uroporphyrinogen with purified uroporphyrinogen decarboxylase were performed. The 3,4,3',4'-tetrachlorobiphenyl and 3,4,5,3',4',5'-hexachlorobiphenyl strongly inhibit uroporphyrinogen decarboxylase directly at two steps. The results confirmed that porphyrinogenic PCBs primarily inhibit uroporphyrinogen decarboxylase, leading to a depletion of heme as a result of which synthesis of ALA synthetase increased.

  3. Porphyrin-laser photodynamic induction of focal brain necrosis

    SciTech Connect

    Stroop, W.G.; Battles, E.J.; Townsend, J.J.; Schaefer, D.C.; Baringer, J.R.; Straight, R.C. )

    1989-09-01

    A noninvasive photodynamic method has been developed to produce focal brain necrosis using porphyrin activated in vivo with laser light. After peripheral injection of the photosensitive porphyrin derivative, Photofrin I, mice were irradiated on the posterior lateral aspect of the head through the intact depilated scalp with 632 nm argon-dye laser light. Animals were studied at one, two and seven days after irradiation. Blood-brain barrier damage was detected by the intravenous injection of Evans blue, horseradish peroxidase and heterologous immunoglobulins. At one and two days after irradiation, the lesions were characterized by extravasation of immunoglobulin and Evans blue, and by edema, ischemia and infiltration by monocytes. On the seventh day after irradiation, the lesion was smaller than it had been two days after irradiation, and had reactive changes at its edges and coagulative necrosis at its center. Extravasation of Evans blue and immunoglobulin was markedly reduced by the seventh day after irradiation, but uptake of horseradish peroxidase by macrophages located at the periphery of the lesion was evident.

  4. Magnetic and electronic properties of porphyrin-based molecular nanowires

    NASA Astrophysics Data System (ADS)

    Zheng, Jia-Jia; Li, Qiao-Zhi; Dang, Jing-Shuang; Wang, Wei-Wei; Zhao, Xiang

    2016-01-01

    Using spin-polarized density functional theory calculations, we performed theoretical investigations on the electronic and magnetic properties of transition metal embedded porphyrin-based nanowires (TM-PNWs, TM = Cr, Mn, Co, Ni, Cu, and Zn). Our results indicate that Ni-PNW and Zn-PNW are nonmagnetic while the rest species are magnetic, and the magnetic moments in TM-PNWs and their corresponding isolated monomer structures are found to be the same. In addition, the spin coupling in the magnetic nanowires can be ignored leading to their degenerate AFM and FM states. These results can be ascribed to the weak intermetallic interactions because of the relatively large distances between neighbor TM atoms. Among all TM-PNW structures considered here, only Mn-PNW shows a half-metallic property while the others are predicted to be semiconducting. The present work paves a new way of obtaining ferromagnetic porphyrin-based nanowires with TM atoms distributed separately and orderly, which are expected to be good candidates for catalysts, energy storage and molecular spintronics.

  5. Imaging of photoinduced tautomerism in single porphyrin molecules

    NASA Astrophysics Data System (ADS)

    Jäger, Regina; Chizhik, Anna M.; Chizhik, Alexey I.; Mack, Hans-Georg; Lyubimtsev, Alexey; Hanack, Michael; Meixner, Alfred J.

    2011-10-01

    In this work we present our new experimental and theoretical results upon investigations of the photoinduced tautomerism processes of single metal-free porphyrin-type molecules. During tautomerization a molecule changes its structure, therefore the excitation transition dipole moment (TDM) of the molecule changes its orientation. Using confocal microscopy in combination with azimuthally and radially polarized laser beams we are able to determine the orientation of the TDM as well as the orientation of a single molecule itself. In the case of tautomerism we are able to visualize this process and even the involved isomers separately. The study first focuses on two symmetrical compounds: a phthalocyanine and a porphyrin. Additionally, differences of the single molecules embedded in a polymer matrix or just spin-coated on a glass cover slide and under nitrogen flow are investigated. In the latter case we observe a higher frequency of the change of the TDM orientation. The experimental studies are supplemented by quantum chemical calculations. Variations of the molecular substituents, the environment and excitation wavelength can give new insights into the excited-state tautomerism process of a single molecule. We also introduce some suggestions for future experiments to support the understanding of the photoinduced tautomerism.

  6. Surface-confined Ullmann coupling of thiophene substituted porphyrins

    NASA Astrophysics Data System (ADS)

    Beggan, J. P.; Boyle, N. M.; Pryce, M. T.; Cafolla, A. A.

    2015-09-01

    The covalent coupling of (5,10,15,20-tetrabromothien-2-ylporphyrinato)zinc(II) (TBrThP) molecules on the Ag(111) surface has been investigated under ultra-high-vacuum conditions, using scanning tunnelling microscopy and x-ray photoelectron spectroscopy. The findings provide atomic-level insight into surface-confined Ullmann coupling of thiophene substituted porphyrins, analyzing the progression of organometallic intermediate to final coupled state. Adsorption of the TBrThP molecules on the Ag(111) surface at room temperature is found to result in the reductive dehalogenation of the bromothienyl substituents and the subsequent formation of single strand and crosslinked coordination networks. The coordinated substrate atoms bridge the proximal thienyl groups of the organometallic intermediate, while the cleaved bromine atoms are bound on the adjacent Ag(111) surface. The intermediate complex displays a thermal lability at ˜423 K that results in the dissociation of the proximal thienyl groups with the concomitant loss of the surface bound bromine. At the thermally induced dissociation of the intermediate complex the resultant thienylporphyrin derivatives covalently couple, leading to the formation of a polymeric network of thiophene linked and meso-meso fused porphyrins.

  7. [Porphyrin excretion in patients with chronic hepatitis C virus infection].

    PubMed

    Armas-Merino, R; Wolff, C; Parraguez, A; Soto, J R

    1997-03-01

    The high prevalence of chronic hepatitis C virus infection in patients with porphyria cutanea tarda, specially in those without family history of the disease, suggests that this could be an acquired disease and one of the most frequent extra hepatic manifestations of hepatitis C virus infection. To study the excretion of porphyrins and its precursors in cirrhotic patients with and without hepatitis C virus infection. Eighteen patients with cirrhosis Child-Pough A, eight infected with hepatitis C virus, were studied. Urinary excretion of [symbol see text] aminolevulinic acid, porphobilinogen, coproporphyrins, uroporphyrins and fecal excretion of coproporphyrins and protoporphyrins were measured. Red blood cell protoporphyrin was also measured. There were no differences in the measured parameters between patients with or without hepatitis C virus infection. No patient had uroporphyrin excretion values over the normal range. Some patients had slight elevations in some parameters, but always below the values observed in porphyrias. In these group of patients, hepatitis C virus infection of its associated liver disease, do not cause detectable alterations in porphyrin metabolism.

  8. Magnetic and electronic properties of porphyrin-based molecular nanowires

    SciTech Connect

    Zheng, Jia-Jia; Li, Qiao-Zhi; Dang, Jing-Shuang; Zhao, Xiang; Wang, Wei-Wei

    2016-01-15

    Using spin-polarized density functional theory calculations, we performed theoretical investigations on the electronic and magnetic properties of transition metal embedded porphyrin-based nanowires (TM-PNWs, TM = Cr, Mn, Co, Ni, Cu, and Zn). Our results indicate that Ni-PNW and Zn-PNW are nonmagnetic while the rest species are magnetic, and the magnetic moments in TM-PNWs and their corresponding isolated monomer structures are found to be the same. In addition, the spin coupling in the magnetic nanowires can be ignored leading to their degenerate AFM and FM states. These results can be ascribed to the weak intermetallic interactions because of the relatively large distances between neighbor TM atoms. Among all TM-PNW structures considered here, only Mn-PNW shows a half-metallic property while the others are predicted to be semiconducting. The present work paves a new way of obtaining ferromagnetic porphyrin-based nanowires with TM atoms distributed separately and orderly, which are expected to be good candidates for catalysts, energy storage and molecular spintronics.

  9. Comparison of radiationless decay processes in osmium and platinum porphyrins

    SciTech Connect

    Ponterini, G.; Serpone, N.; Bergkamp, M.A.; Netzel, T.L.

    1983-01-01

    Two osmium porphyrin complexes, Os(OEP)L/sub 2/ (OEP = octaethylporphin, L = py(pyridine) or NO), and PtOEP were investigated by picosecond laser spectroscopy with use of a double-beam, mode-locked Nd:glass system delivering 6-ps (fwhm) pulses at 527 nm with 1-2mJ/pulse. Time-resolved excited-state spectra were recorded from the time of photoexcitation to 5 ns after photoexcitation. The initial excited state, S/sub 1/, decayed in less than or equal to9 ps for the two osmium complexes and in less than or equal to15 ps for the platinum porphyrin. A second excited state, T/sub 1/, lived for 1, 9, and >50 ns respectively for Os(OEP)(py)/sub 2/, Os(OEP)(NO)/sub 2/, and PtOEP. The ..delta..A spectra of the T/sub 1/ states of the osmium complexes were similar to those of previously reported (d/sub ..pi../,..pi..*) states for Os(OEP)(py)/sub 2/ and (..pi..,..pi..*) states for Os(OEP)(NO)/sub 2/. This finding supports prior assignments of these states on the basis of expected axial and equatorial back-bonding of the osmium's d electrons. Additionally, a long-lived (tau > 5 ns) photochemical product (probably a result of ligand loss) was found in the case of Os(OEP)(py)/sub 2/.

  10. DFT study of core-modified porphyrin isomers

    NASA Astrophysics Data System (ADS)

    Soujanya, Y.; Punnagai, M.; Sateesh, B.; Sastry, G. Narahari

    B3LYP/6-311+G** calculations were performed systematically on 1,2 (syn) and 1,3 (anti) tautomeric forms of oxa- and thia- core-modified porphyrin isomers, which resulted in a total of 86 structures. The structural and energetic variation in all the isomers were analyzed. In corrphycene, hemiporphycene and porphycene the Z forms are more stable compared to the corresponding E forms in both the anti and syn oxa- and thiaporphyrin isomers. In contrast, in the syn isomeric forms of [3.0.1.0], [3.1.0.0] and [4.0.0.0] oxaporphyrins and in both syn and anti forms of thiaporphyrin isomers, Z forms are less stable. The HOMO and LUMO values are both negative and varied in a narrow zone, indicating no dramatic effect on the position of heteroatom substitution on the redox properties. The effect of geometric constraints due to the alteration of meso-bridge length and the hetero atom disposition in the porphyrin core on the relative stabilities of the isomers is analyzed.

  11. Tin-porphyrin-assisted formation of coordination frameworks

    NASA Astrophysics Data System (ADS)

    Titi, Hatem M.

    2016-09-01

    Novel 3D networks synthesized by two different methods are reported in this article. Structure 1 {[CdL2]·(solvent)}n consists of CdII-single metallic nodes held together by coordinated isonicotinate ligands (L) to form a 3D chiral framework (P41212). The resulting structure exhibits threefold-interpenetrated dia coordination networks. After a few weeks the crystals were re-measured to form 1a {[Cd(L)2(H2O)]·DMF}n with two interpenetrated dia nets which is thermodynamically more stable. On the other hand, the addition of the tin(IV)-porphyrin to the same reaction mixture led to the formation of 3D pseudo-isostructures, based on oxo-centered CdII and MnII/III cluster nodes, 2 {[Cd3(OH)L4(H2O)3](ClO4)}n and 3 {[Mn3(O)L4(DMF)3](ClO4)}n. These structures represent topologically bcg nets. Possible synthetic mechanism was proposed to emphasize the role of the tin(IV)-porphyrin that led to the construction of oxo-centered trinuclear clusters in 2 and 3.

  12. Porphyrin Based neuton capture agents for cancer therapy

    DOEpatents

    Vicente, Maria Da; Shetty, Shankar Jayaram; Jaquinod, Laurent; Smith, Kevin M.

    2006-06-27

    The invention describes the synthesis of a panel of novel carbon-carbon linked carboranyl-containing 5,10,15,20-tetraphenylporphyrins bearing 25–44% boron by weight. In certain embodiments, a phenyl porphyrin compound has a carboranyl group attached to the phenyl group by a carbon-carbon linkage, wherein the phenyl group corresponds to the following formula embedded image
    where R7 through R11 are hydrogen, a carboranyl group, or are selected from the group consisting of hydroxyl, NMe3+, PMePh2+, PO(OH)2, SO3H, COOH, and NH2. In this embodiment, the carboranyl group is attached to the phenyl group by a carbon-carbon linkage, either one or two of R7 through R11 are other than hydrogen; and the phenyl porphyrin compound contains at least one phenyl group having at least one of said carboranyl groups.

  13. Anticancer Gold(III) Porphyrins Target Mitochondrial Chaperone Hsp60.

    PubMed

    Hu, Di; Liu, Yungen; Lai, Yau-Tsz; Tong, Ka-Chung; Fung, Yi-Man; Lok, Chun-Nam; Che, Chi-Ming

    2016-01-22

    Identification of the molecular target(s) of anticancer metal complexes is a formidable challenge since most of them are unstable toward ligand exchange reaction(s) or biological reduction under physiological conditions. Gold(III) meso-tetraphenylporphyrin (gold-1 a) is notable for its high stability in biological milieux and potent in vitro and in vivo anticancer activities. Herein, extensive chemical biology approaches employing photo-affinity labeling, click chemistry, chemical proteomics, cellular thermal shift, saturation-transfer difference NMR, protein fluorescence quenching, and protein chaperone assays were used to provide compelling evidence that heat-shock protein 60 (Hsp60), a mitochondrial chaperone and potential anticancer target, is a direct target of gold-1 a in vitro and in cells. Structure-activity studies with a panel of non-porphyrin gold(III) complexes and other metalloporphyrins revealed that Hsp60 inhibition is specifically dependent on both the gold(III) ion and the porphyrin ligand.

  14. Normal-Coordinate Structural Decomposition and the Vibronic Spectra of Porphyrins

    SciTech Connect

    SHELNUTT,JOHN A.

    1999-11-09

    The connection is made between the normal-coordinate structural decomposition (NSD) and the vibronic molecular states and spectra of porphyrins. NSD is a procedure that provides a description of the distortion of a porphyrin from a D{sub 4h} symmetric reference structure in terms of equivalent displacements along the normal coordinates. Expressions for the optical absorption spectra with vibrational structure are developed with these NSD-determined deformations as parameters, and the expressions are applied to the UV-visible absorption spectra porphyrins.

  15. Estimation of porphyrin concentration in the kerogen fraction of shales using high-resolution reflectance spectroscopy

    NASA Technical Reports Server (NTRS)

    Holden, Peter N.; Gaffey, Michael J.; Sundararaman, P.

    1991-01-01

    An interpretive model for estimating porphyrin concentration in bitumen and kerogen from spectral reaflectance data in the visible and near-ultraviolet region of the spectrum is derived and calibrated. Preliminary results obtained using the model are consistent with concentrations determined from the bitumen extract and suggest that 40 to 60 percent of the total porphyrin concentration remains in the kerogen after extraction of bitumen from thermally immature samples. The reflectance technique will contribute to porphyrin and kerogen studies and can be applied at its present level of development to several areas of geologic and paleo-oceanographic research.

  16. A porous covalent porphyrin framework with exceptional uptake capacity of saturated hydrocarbons for oil spill cleanup.

    PubMed

    Wang, Xi-Sen; Liu, Jian; Bonefont, Jean M; Yuan, Da-Qiang; Thallapally, Praveen K; Ma, Shengqian

    2013-02-21

    A highly porous porphyrin-based organic polymer, PCPF-1, was constructed via homo-coupling reaction of the custom-designed porphyrin ligand, 5,10,15,20-tetrakis(4-bromophenyl)porphyrin. PCPF-1 possesses a large BET surface area of over 1300 m(2) g(-1) (Langmuir surface area of over 2400 m(2) g(-1)) and exhibits strong hydrophobicity with a water contact angle of 135°, and these features afford it the highest adsorptive capacities for saturated hydrocarbons and gasoline among sorbent materials reported thus far, as well as render it the capability to remove oil from water.

  17. A porphyrin-polyoxometallate bio-inspired mimic for artificial photosynthesis.

    PubMed

    Elliott, Kristopher J; Harriman, Anthony; Le Pleux, Loïc; Pellegrin, Yann; Blart, Errol; Mayer, Cédric R; Odobel, Fabrice

    2009-10-21

    A multi-porphyrin cluster has been covalently attached to a polyoxometallate (POM) catalyst so as to form an advanced model for the photosynthetic reaction complex. This bio-inspired mimic displays efficient energy transfer from the peripheral zinc porphyrins (ZnP) to the central free-base porphyrin (FbP). The latter species participates in a light-induced electron transfer with the POM. Charge recombination is hindered by hole transfer from the FbP to one of the ZnPs. Charge accumulation occurs at the POM under illumination in the presence of a sacrificial electron donor.

  18. Porphyrin π-stacking in a heme protein scaffold tunes gas ligand affinity.

    PubMed

    Weinert, Emily E; Phillips-Piro, Christine M; Marletta, Michael A

    2013-10-01

    The role of π-stacking in controlling redox and ligand binding properties of porphyrins has been of interest for many years. The recent discovery of H-NOX domains has provided a model system to investigate the role of porphyrin π-stacking within a heme protein scaffold. Removal of a phenylalanine-porphyrin π-stack dramatically increased O2, NO, and CO affinities and caused changes in redox potential (~40mV) without any structural changes. These results suggest that small changes in redox potential affect ligand affinity and that π-stacking may provide a novel route to engineer heme protein properties for new functions.

  19. Aggregation of asphaltene model compounds using a porphyrin tethered to a carboxylic acid.

    PubMed

    Schulze, Matthias; Lechner, Marc P; Stryker, Jeffrey M; Tykwinski, Rik R

    2015-07-07

    A Ni(II) porphyrin functionalized with an alkyl carboxylic acid (3) has been synthesized to model the chemical behavior of the heaviest portion of petroleum, the asphaltenes. Specifically, porphyrin 3 is used in spectroscopic studies to probe aggregation with a second asphaltene model compound containing basic nitrogen (4), designed to mimic asphaltene behavior. NMR spectroscopy documents self-association of the porphyrin and aggregation with the second model compound in solution, and a Job's plot suggests a 1 : 2 stoichiometry for compounds 3 and 4.

  20. Fluorenyl porphyrins for combined two-photon excited fluorescence and photosensitization

    NASA Astrophysics Data System (ADS)

    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.

  1. Self-assembling discotic liquid crystal porphyrin into more controllable ordered nanostructure mediated by fluorophobic effect

    SciTech Connect

    Zhou, Xiaoli; Kang, Shin-Woong; Kumar, Satyendra; Li, Quan

    2009-09-02

    The novel nanoscale discotic liquid crystal porphyrin with partial chain perfluorination, which has the same basic structure as the best photoreceptor in nature (chlorophyll), shows an exceptionally enhanced tendency to self-assemble into ordered nanostructure. Defect-free homeotropically aligned fluorinated porphyrin thin films were, for the first time, fabricated and characterised. The ability to self-assemble large {pi}-conjugated discotic molecules into highly ordered nanostructure via partial chain perfluorination provides new insight for the bottom-up nanofabrication of molecular devices. The controllable ordered porphyrin nanostructure with directed molecular arrangement holds great promise for use in high-performance electronic devices.

  2. Light-induced electrical switching of porphyrin-covered silicon nanowire FETs (presentation video)

    NASA Astrophysics Data System (ADS)

    Cuniberti, Gianaurelio

    2014-03-01

    Nanowires represent excellent building blocks for future nanoelectronics, due to their efficient charge transport characteristics. Here we present light-induced switching behaviour of porphyrin-coated silicon nanowire field effect transistors (Si NW FETs) and demonstrate their capabilities for design of hybrid nanodevices - consisting of organic complexes and inorganic nanowires. Switching of Si NW FETs highly reflects the electrical change of porphyrin molecules by light. To demonstrate significant factors of concentration-dependent switching of porphyrin-covered devices, electrical charging mechanism through molecules and nanowires has been understood, that allows the systematic integration of the hybrid devices.

  3. Estimation of porphyrin concentration in the kerogen fraction of shales using high-resolution reflectance spectroscopy

    NASA Technical Reports Server (NTRS)

    Holden, Peter N.; Gaffey, Michael J.; Sundararaman, P.

    1991-01-01

    An interpretive model for estimating porphyrin concentration in bitumen and kerogen from spectral reaflectance data in the visible and near-ultraviolet region of the spectrum is derived and calibrated. Preliminary results obtained using the model are consistent with concentrations determined from the bitumen extract and suggest that 40 to 60 percent of the total porphyrin concentration remains in the kerogen after extraction of bitumen from thermally immature samples. The reflectance technique will contribute to porphyrin and kerogen studies and can be applied at its present level of development to several areas of geologic and paleo-oceanographic research.

  4. Asymmetric gas separation membranes

    SciTech Connect

    Malon, R. F.; Zampini, A.

    1984-12-04

    Asymmetric gas separation membranes of materials having selective permeation of at least one gas of a gaseous mixture over that of one or more remaining gases of the gaseous mixture, exhibit significantly improved permeation selectivities for the at least one gas when the asymmetric membrane is contacted on one or both surfaces with an effective amount of a Lewis acid. The improved asymmetric gas separation membranes, process for producing the improved membrane, and processes utilizing such membranes for selectively separating at least one gas from a gaseous mixture by permeation are disclosed.

  5. Asymmetric gas separation membranes

    SciTech Connect

    Malon, R. F.; Zampini, A.

    1984-09-18

    Asymmetric gas separation membranes of materials having selective permeation of at least one gas of a gaseous mixture over that of one or more remaining gases of the gaseous mixture, exhibit significantly improved permeation selectivities for the at least one gas when the asymmetric membrane is contacted on one or both surfaces with an effective amount of a Br nsted-Lowry acid. The improved asymmetric gas separation membranes, process for producing the improved membrane, and processes utilizing such membranes for selectively separating at least one gas from a gaseous mixture by permeation are disclosed.

  6. Comparison of the hydrodynamics and mass transfer characteristics in internal-loop airlift bioreactors utilizing either a novel membrane-tube sparger or perforated plate sparger.

    PubMed

    Wei, Ce; Wu, Bing; Li, Ganlu; Chen, Kequan; Jiang, Min; Ouyang, Pingkai

    2014-11-01

    Two gas spargers, a novel membrane-tube sparger and a perforated plate sparger, were compared in terms of hydrodynamics and mass transfer (or oxygen transfer) performance in an internal-loop airlift bioreactor. The overall gas holdup ε T, downcomer liquid velocity V d, and volumetric mass transfer coefficient K L a were examined depending on superficial gas velocity U G increased in Newtonian and non-Newtonian fluids for the both spargers. Compared with the perforated plate sparger, the bioreactor with the membrane-tube sparger increased the values of ε T by 4.9-48.8% in air-water system when the U G was from 0.004 to 0.04 m/s, and by 65.1-512.6% in air-CMC solution system. The V d value for the membrane-tube sparger was improved by 40.0-86.3%. The value of K L a was increased by 52.8-84.4% in air-water system, and by 63.3-836.3% in air-CMC solution system. Empirical correlations of ε T, V d, and K L a were proposed, and well corresponding with the experimental data with the deviation of 10%.

  7. Preparation and characterization of sterile sub-200 nm meso-tetra(4-hydroxylphenyl)porphyrin-loaded nanoparticles for photodynamic therapy.

    PubMed

    Konan, Yvette Niamien; Cerny, Radovan; Favet, Joselyne; Berton, Myriam; Gurny, Robert; Allémann, Eric

    2003-01-01

    A photosensitizer, meso-tetra(4-hydroxyphenyl)porphyrin, was incorporated into sub-150 nm nanoparticles using the emulsification-diffusion technique in order to perform sterilization by filtration using 0.22 microm membranes. The three selected polyesters (poly(D,L-lactide-co-glycolide), (50:50 PLGA, 75:25 PLGA) and poly(D,L-lactide (PLA)) for the nanoparticle production were all amorphous in nature and have similar molecular weights but different copolymer molar ratios. The influence of the copolymer molar ratio and the theoretical drug loading was investigated in terms of particle size, drug loading, entrapment efficiency and surface characteristics. With all the polymers used, sub-150 nm nanoparticles were produced with good reproducibility and narrow size distributions irrespective of both the polymer nature and the theoretical drug loading. After purification by cross-flow filtration, the nanoparticle suspensions were sterilized by membrane filtration and freeze-dried in the presence of a lyoprotectant (trehalose). For all types of nanoparticles, complete redispersion in various media could be obtained. All final freeze-dried products were refiltrable on a 0.22 microm membrane and were stable in terms of mean particle size and drug loading over a period up to 6 months. The effective drug loading increased at higher theoretical drug loading, the entrapment efficiency was however decreased. The same trend was observed with the three polyesters. The sterility of the final freeze-dried nanoparticles was confirmed by the results of the sterility testing which showed no bacterial contamination.

  8. Synthesis and electrochemistry of β-pyrrole nitro-substituted cobalt(II) porphyrins. The effect of the NO₂ group on redox potentials, the electron transfer mechanism and catalytic reduction of molecular oxygen in acidic media.

    PubMed

    Sun, Bin; Ou, Zhongping; Yang, Shuibo; Meng, Deying; Lu, Guifen; Fang, Yuanyuan; Kadish, Karl M

    2014-07-28

    Four cobalt(II) porphyrins, two of which contain a β-pyrrole nitro substituent, were synthesized and characterized by electrochemistry and spectroelectrochemistry. The investigated compounds are represented as (TRPP)Co and (NO2TRPP)Co, where TRPP is the dianion of a substituted tetraphenylporphyrin and R is a CH3 or OCH3 substituent on the four phenyl rings of the macrocycle. Two reductions and three oxidations are observed for each compound in CH2Cl2 containing 0.10 M tetra-n-butylammonium perchlorate. The first reduction of the compounds without a nitro substituent is metal-centered and leads to formation of a Co(I) porphyrin which then reacts with the CH2Cl2 solvent to generate a carbon σ-bonded Co(III)-R complex. A further reduction then occurs at more negative potentials to generate an unstable Co(II) σ-bonded compound. In contrast to these reactions, the first reduction of the nitro-substituted porphyrins is macrocycle-centered under the same solution conditions and gives a Co(II) porphyrin π-anion radical product. This reversible electron transfer is then followed at more negative potentials by a second reversible one-electron addition to give a Co(II) dianion. Three reversible one-electron oxidations are also seen for each compound. The first is metal-centered and the next two involve the conjugated π-system of the macrocycle. Each neutral Co(II) porphyrin was also examined as to its catalytic activity for electroreduction of molecular oxygen when coated on an edge-plane pyrolytic graphite electrode in 1.0 M HClO4. The β-pyrrole nitro-substituted derivatives were shown to be better catalysts than the non-nitro substituted compounds under the utilized experimental conditions.

  9. Influence of structural variations in push-pull zinc porphyrins on photovoltaic performance of dye-sensitized solar cells.

    PubMed

    Yi, Chenyi; Giordano, Fabrizio; Cevey-Ha, Ngoc-Le; Tsao, Hoi Nok; Zakeeruddin, Shaik M; Grätzel, Michael

    2014-04-01

    We designed and synthesized two new zinc porphyrin dyes for dye-sensitized solar cells (DSCs). Subtle molecular structural variation in the dyes significantly influenced the performance of the DSC devices. By utilizing these dyes in combination with a cobalt-based redox electrolyte using a photoanode made of mesoporous TiO2 , we achieved a power conversion efficiency (PCE) of up to 12.0 % under AM 1.5 G (100 mW cm(-2)) simulated solar light. Moreover, we obtained a high PCE of 6.4 % for solid-state dye-sensitized solar cells by using 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene as a hole-transporting material.

  10. Fluorinated Dodecaphenylporphyrins: Synthetic and Electrochemical Studies Including the First Evidence of Intramolecular Electron Transfer Between an Fe(II) Porphyrin -Anion Radical and an Fe(I) Porphyrin

    SciTech Connect

    D'Souza, F.; Forsyth, T.P.; Fukuzumi, S.; Kadish, K.M.; Krattinger, B.; Lin, M.; Medforth, C.J.; Nakanishi, I.; Nurco, D.J.; Shelnutt, J.A.; Smith, K.M.; Van Caemelbecke, E.

    1998-10-19

    Dodecaphenylporphyrins with varying degrees of fluorination of the peripheral phenyl rings (FXDPPS) were synthesized as model compounds for studying electronic effects in nonplan~ porphyrins, and detailed electrochemical studies of the chloroiron(HI) complexes of these compounds were undertaken. The series of porphyrins, represented as FeDPPCl and as FeFXDPPCl where x = 4, 8 (two isomers), 12, 20,28 or 36, could be reversibly oxidized by two electrons in dichloromethane to give n-cation radicals and n-dications. All of the compounds investigated could also be reduced by three electrons in benzonitrile or pyridine. In benzonitrile, three reversible reductions were observed for the unfluorinated compound FeDPPC1, whereas the FeFXDPPCl complexes generally exhibited irreversible first and second reductions which were coupled to chemical reactions. The chemical reaction associated with the first reduction involved a loss of the chloride ion after generation of Fe FXDPPC1. The second chemical reaction involved a novel intramolecular electron transfer between the initially generated Fe(H) porphyrin n-anion radical and the final Fe(I) porphyrin reduction product. In pyridine, three reversible one electron reductions were observed with the second reduction affording stable Fe(II) porphyrin o - anion radicals for ail of the complexes investigated.

  11. Porphyrin-Based Porous Organic Frameworks as a Biomimetic Catalyst for Highly Efficient Colorimetric Immunoassay.

    PubMed

    Deng, Xiao; Fang, Yishan; Lin, Sha; Cheng, Qian; Liu, Qingyun; Zhang, Xiaomei

    2017-02-01

    Herein, we synthesized a cost-effective iron porphyrin (FePor)-based covalent organic polymer (COP), FePor-TFPA-COP, through an easy aromatic substitution reaction between pyrrole and tris(4-formylphenyl)amine (TFPA). The triangular pyramid-shaped, N-centric structure of TFPA facilitated the formation of FePor-TFPA-COP with three-dimensional porous structure, larger surface area, and abundant surface catalytically active sites. FePor-TFPA-COP exhibited strong intrinsic peroxidase activity toward a classical peroxidase substrate, 3,3',5,5'-tetramethylbenzidine (TMB), in the presence of H2O2. Compared with horseradish peroxidase (HRP), FePor-TFPA-COP exhibited several advantages such as easy storage, high sensitivity, and prominently chemical and catalytic stability under the harsh conditions, which guaranteed the accuracy and reliability of measurements. Utilizing the excellent catalytic activity, a FePor-TFPA-COP-based colorimetric immunoassay was first established for α-fetoprotein (AFP) detection and showed high sensitivity, stability, and acceptable reproducibility. The linear response range for AFP was 5 pg/mL to 100 ng/mL and the detection limitation was 1 pg/mL. The routine provided a brilliant biomimetic catalyst to develop the nonenzyme immunoassay. More importantly, the high chemical and catalytic stability and sensitivity facilitated future practical applications under various conditions.

  12. Volume and enthalpy profiles of CO binding to Fe(II) tetrakis-(4-sulfonatophenyl)porphyrin.

    PubMed

    Barker, B D; Larsen, R W

    2001-06-01

    The focus of this study is to examine volume and enthalpy profiles of ligand binding associated with CO-Fe(II) tetrakis-(4-sulfonato phenyl)-porphyrin (COFe(II)4SP) in aqueous solution. Temperature dependent photothermal beam deflection was employed to probe the overall enthalpy and volume changes associated with CO-photolysis and recombination. The analysis demonstrates that ligand recombination occurs with a pseudo first order rate constant of (2.5+/-0.2)x10(4) s(-1) (at 25 degrees C) with a corresponding volume decrease of 6+/-1 ml/mol. The activation enthalpy (DeltaH(double dagger)) and volume (DeltaV(double dagger)) change for CO recombination (determined from temperature/pressure dependent transient absorption spectroscopy) are found to be 3.9 kcal/mol and 8.2 ml/mol, respectively. These data are consistent with a mechanism in which photolysis yields a five-coordinate high spin (H(2)O)Fe(II)4SP complex that recombines in a single step to form the low spin (CO)(H(2)O)Fe(II)4SP complex. Base elimination, often associated with CO photolysis from hemes, is not observed in this system. The overall volume changes suggest a transition state with significant high spin character. Furthermore, these results demonstrate the utility of coupling photothermal techniques with variable pressure/temperature transient absorption spectroscopy to probe heme reaction dynamics.

  13. Luminescence diagnostics of malignant tumors in the IR spectral range using Yb-porphyrin metallocomplexes

    NASA Astrophysics Data System (ADS)

    Ivanov, A. V.; Rumyantseva, V. D.; Shchamkhalov, K. S.; Shilov, I. P.

    2010-12-01

    The creation and application of new low-toxic photosensitizers for the luminescence diagnostics of cancer are considered. The new photosensitizers weakly generate singlet oxygen, exhibit developed luminescence, and retain the tumor-tropic properties of the therapeutic photosensitizers. Twenty one ytterbium complexes of porphyrin compounds that differ by the substituents at the periphery of the porphyrin ring are synthesized. The absorption and luminescence spectra and the luminescence decay curves of these substances are studied. The primary toxicological and pharmacokinetic investigations are performed for the most promising compounds in the organisms of experimental animals. The experimental data prove that the Yb-porphyrin complexes are promising as low-toxic markers for the luminescence diagnostics of malignant tumors in the IR spectral range (975-985 nm) that are free of the phototoxicity typical of the conventional porphyrins at a relatively high luminescence contrast and the selective accumulation in tissue.

  14. Acid-base and coordination properties of Meso-substituted porphyrins in nonaqueous solutions

    NASA Astrophysics Data System (ADS)

    Pukhovskaya, S. G.; Nam, Dao Tkhe; Fien, Chan Ding; Domanina, E. N.; Ivanova, Yu. B.; Semeikin, A. S.

    2017-09-01

    Acid-base and coordination properties of alkyl and aryl meso-substituted porphyrins are studied spectrophotometrically in nonaqueous solutions. It is found that the nature of the substituent greatly affects the basicity of ligands for porphyrins characterized by a flat structure of macrocycle. The electronic effects of substituents have a much weaker influence on the kinetics of complexing. These effects could be due to the opposite orientation of some factors: an increase in the basicity and stability of the N-H bonds of porphyrin reaction centers. Dissociation constants p K b of the cationic forms of meso-substituted derivatives of porphyrin are measured. The values of p K b are in good agreement with classic concepts of the nature of substituents, particularly those indirectly included in the macrocycle through phenyl buffer rings.

  15. Bio-inspired photoresponse of porphyrin-attached gold nanoparticles on a field-effect transistor.

    PubMed

    Miyachi, Mariko; Yamanoi, Yoshinori; Nakazato, Kazuo; Nishihara, Hiroshi

    2014-09-01

    A bio-inspired photoresponse was engineered in porphyrin-attached Au nanoparticles (AuNPs) on a field-effect transistor (FET). The system mimics photosynthetic electron transfer, using porphyrin derivatives as photosensitizers and AuNPs as photoelectron counting devices. Porphyrin-protected AuNPs were immobilized onto the gate of an FET via the formation of self-assembled monolayers. Photoinduced electron transfer from the porphyrin led to single electron transfer at the Au nanoparticles, which was monitored via a changing gate voltage on the FET in the presence of organic electrolyte. The further attachment of other functional molecules to this system should enable various other potential functionalities. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. XAFS and crystallographic studies of Ni(II) porphyrins in single crystals and in solution

    SciTech Connect

    Renner, M.W.; Furenlid, L.R.; Barkigia, K.M.; Fajer, J.

    1996-09-01

    Abstract. Nickel porphyrins serve as models for the active sites of several biological processes. Crystallographic and EXAFS results for a Ni meso-tetrapropyl porphyrin (NiTPrP) yield different Ni-N distances in solution and in the solid state. The Ni-N distances determined by single crystal polarized XAS and X-ray diffraction agree well. Polarized XANES experiments further establish that the pre-edge feature observed in square planar Ni(II) complexes is a ls-4pz transition. The single crystal and solution EXAFS results demonstrate that conformational variations of the porphyrin macrocycle can readily be imposed by environmental and/or packing forces and can thereby modulate the chemical and physical properties of porphyrinic chromophores and prosthetic groups.

  17. Methods and intermediates for the synthesis of dipyrrin-substituted porphyrinic macrocycles

    DOEpatents

    Yu, Lianhe [Raleigh, NC; Muthukumaran, Kannan [Raleigh, NC; Sreedharan, Prathapan [Kerata, IN; Lindsey, Jonathan S [Raleigh, NC

    2011-05-24

    The present invention provides dipyrrin substituted porphyrinic macrocycles, intermediates useful for making the same, and methods of making the same. Such compounds may be used for purposes including the making of molecular memory devices, solar cells and light harvesting arrays.

  18. Methods and intermediates for the synthesis of dipyrrin-substituted porphyrinic macrocycles

    DOEpatents

    Yu, Lianhe; Muthukumaran, Kannan; Sreedharan, Prathapan; Lindsey, Jonathan S.

    2010-05-25

    The present invention provides dipyrrin substituted porphyrinic macrocycles, intermediates useful for making the same, and methods of making the same. Such compounds may be used for purposes including the making of molecular memory devices, solar cells and light harvesting arrays.

  19. Methods and intermediates for the synthesis of dipyrrin-substituted porphyrinic macrocycles

    DOEpatents

    Yu, Lianhe [Raleigh, NC; Muthukumaran, Kannan [Raleigh, NC; Sreedharan, Prathapan [Kerala, IN; Lindsey, Jonathan S [Raleigh, NC

    2012-03-06

    The present invention provides dipyrrin substituted porphyrinic macrocycles, intermediates useful for making the same, and methods of making the same. Such compounds may be used for purposes including the making of molecular memory devices, solar cells and light harvesting arrays.

  20. The ligand influence in stereoselective carbene transfer reactions promoted by chiral metal porphyrin catalysts.

    PubMed

    Intrieri, Daniela; Carminati, Daniela Maria; Gallo, Emma

    2016-10-12

    The use of diazo reagents of the general formula N2C(R)(R(1)) as carbene sources to create new C-C bonds is of broad scientific interest due to the intrinsic sustainability of this class of reagents. In the presence of a suitable catalyst, diazo reagents react with several organic substrates with excellent stereo-control and form N2 as the only by-product. In the present report the catalytic efficiency of metal porphyrins in promoting carbene transfer reactions is reviewed with emphasis on the active role of the porphyrin skeleton in stereoselectively driving the carbene moiety to the target substrate. The catalytic performances of different metal porphyrins are discussed and have been related to the structural features of the ligand with the final aim of rationalizing the strict correlation between the three-dimensional structure of the porphyrin ligand and the stereoselectivity of carbene transfer reactions.

  1. Electrocatalytic miRNA Detection Using Cobalt Porphyrin-Modified Reduced Graphene Oxide

    PubMed Central

    De Souza, Camille; Zrig, Samia; Wang, Dengjun; Pham, Minh-Chau; Piro, Benoit

    2014-01-01

    Metalated porphyrins have been described to bind nucleic acids. Additionally, cobalt porphyrins present catalytic properties towards oxygen reduction. In this work, a carboxylic acid-functionalized cobalt porphyrin was physisorbed on reduced graphene oxide, then immobilized on glassy carbon electrodes. The carboxylic groups were used to covalently graft amino-terminated oligonucleotide probes which are complementary to a short microRNA target. It was shown that the catalytic oxygen electroreduction on cobalt porphyrin increases upon hybridization of miRNA strand (“signal-on” response). Current changes are amplified compared to non-catalytic amperometric system. Apart from oxygen, no added reagent is necessary. A limit of detection in the sub-nanomolar range was reached. This approach has never been described in the literature. PMID:24915180

  2. Highly asymmetrical porphyrins with enhanced push-pull character for dye-sensitized solar cells.

    PubMed

    Kurotobi, Kei; Toude, Yuuki; Kawamoto, Kyosuke; Fujimori, Yamato; Ito, Seigo; Chabera, Pavel; Sundström, Villy; Imahori, Hiroshi

    2013-12-09

    A porphyrin π-system has been modulated by enhancing the push-pull character with highly asymmetrical substitution for dye-sensitized solar cells for the first time. Namely, both two diarylamino moieties as a strong electron-donating group and one carboxyphenylethynyl moiety as a strong electron-withdrawing, anchoring group were introduced into the meso-positions of the porphyrin core in a lower symmetrical manner. As a result of the improved light-harvesting property as well as high electron distribution in the anchoring group of LUMO, a push-pull-enhanced, porphyrin-sensitized solar cell exhibited more than 10% power conversion efficiency, which exceeded that of a representative highly efficient porphyrin (i.e., YD2)-sensitized solar cell under optimized conditions. The rational molecular design concept based on highly asymmetric, push-pull substitution will open the possibilities of further improving cell performance in organic solar cells.

  3. Accumulation of porphyrins in Propionibacterium acnes by 5-aminolevulinic acid and its esters.

    PubMed

    Ogata, Arisa; Hasunuma, Yuya; Kikuchi, Emii; Ishii, Takuya; Ishizuka, Masahiro; Tokuoka, Yoshikazu

    2017-09-01

    We have investigated the accumulation of porphyrins in Propionibacterium acnes (P.acnes) by 5-aminolevulinic acid hydrochloride (ALA) and its esters, ALA methyl ester hydrochloride (mALA), ALA octyl ester hydrochloride (oALA), and ALA benzyl ester hydrochloride (bALA). From the fluorescence spectra of porphyrins accumulated in P.acnes, the order of porphyrin accumulation is as follows: ALA≫mALA≈bALA>oALA (≈0). Moreover, the PDT efficacy is reduced in the order of ALA>mALA≈bALA>oALA (≈without additives). These results confirm that ALA is superior to ALA esters in accumulating porphyrins in P.acnes. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Cationic pyridinium porphyrins appending different peripheral substituents: spectroscopic studies on their interactions with bovine serum albumin.

    PubMed

    Zhao, Ping; Huang, Jin-Wang; Ji, Liang-Nian

    2012-03-01

    The interaction of cationic pyridinium porphyrins appending methylpyridyl, hydroxyphenyl, propionoxyphenyl or carboxyphenyl group at meso-20-position of porphyrin core with bovine serum albumin (BSA), was studied by the combination of absorption spectroscopy, surface-enhanced Raman spectroscopy (SERS), circular dichroism (CD) spectroscopy, fluorescence spectroscopy and synchronous spectroscopy. The spectral monitoring results indicate that the studied compounds could bind with the BSA molecule and the calculated binding constants show that the tetracationic porphyrin has higher binding affinity than those tricationic ones. The interactions between porphyrins and BSA employ an electrostatic binding mechanism and there was only one binding site which located on the surface of the protein molecule. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Synthesis and stereochemistry of highly unsymmetric beta,meso-linked porphyrin arrays.

    PubMed

    Götz, Daniel C G; Bruhn, Torsten; Senge, Mathias O; Bringmann, Gerhard

    2009-11-06

    Porphyrin arrays with tailor-made photophysical properties and well-defined three-dimensional geometries constitute attractive synthetic targets in porphyrin chemistry. The paper describes a variable, straightforward synthetic procedure for the construction of beta,meso-linked porphyrin multichromophores in good to excellent yields. In a Suzuki-type coupling reaction beta-borylated 5,10,15,20-tetraarylporphyrins (TAPs) served as versatile building blocks for the preparation of a plethora of directly linked, unsymmetrically substituted di- and triporphyrins. Besides their interesting photophysical properties, especially the trimeric porphyrin arrays show exciting stereochemical features. The established protocols thus open a convenient entry into the synthesis of achiral and chiral, unsymmetrically substituted beta,meso-linked oligoporphyrins, e.g., for applications in biomedicine or nonlinear optics.

  6. Synthesis and different substituent effects on spectral and electrochemical properties of porphyrin nicotinic acid binary compounds

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Cheng, Xiuli; Shi, Yuhua; Sun, Erjun; Tang, Xuexin; Zhuang, Changfu; Shi, Tongshun

    2009-01-01

    The porphyrin nicotinic acid binary compounds with different substituents in porphine rings (5-(4-nicotinicoxyldecyloxy)phenyl-10,15,20-triphenylporhyrin 2a, 5-(4-nicotinicoxyldecyloxy)phenyl-10,15,20-tri(4-chlorophenyl)porphyrin 2b and 5-(4-nicotinicoxyldecyloxy)phenyl-10,15,20-tri(4-methoxyphenyl)porphyrin 2c) were synthesized. All of them have been characterized, assigned and analyzed by UV-vis, IR, MS and 1H NMR spectra. Their electrochemical and spectroscopic properties were studied by using cyclic voltammetry, fluorescence spectra and Resonance Raman spectra. Different substituents have a little influence on electrochemical behavior and fluorescence spectra. In the Resonance Raman spectra, the substituent has little influence on the skeleton vibration of porphyrin and has much influence on the vibration of phenyl.

  7. Synthesis, Spectroscopic, and Biological Studies on New Zirconium(IV) Porphyrins with Axial Ligand.

    PubMed

    Bajju, Gauri D; Devi, Gita; Katoch, Sapna; Bhagat, Madhulika; Deepmala; Ashu; Kundan, Sujata; Anand, Sunil Kumar

    2013-01-01

    A series of parasubstituted tetraphenylporphyrin zirconium(IV) salicylate complexes (SA/5-SSAZr(IV)RTPP, R = p-H, p-CH3, p-NO2, p-Cl, SA = salicylate, and 5-SSA = 5-sulfosalicylate) have been synthesized, and the spectral properties of free base porphyrins, their corresponding metallated, and axially ligated zirconium(IV) porphyrin compounds were compared with each other. A detailed analysis of ultraviolet-visible (UV-vis), proton nulcear magnetic resonance ((1)H NMR) spectroscopy, infrared (IR) spectroscopy, and elemental analysis suggested the transformation from free base porphyrins to zirconium(IV) porphyrins. The ability of the metal in this complex for extra coordination of solvent molecules was confirmed by ESI-MS spectra. Besides the fluorescence, cyclic voltammetry, and thermogravimetric studies, the complexes were also screened for antimicrobial and anticancer activities. Among all the complexes, 5-SSAZr(p-NO2TPP) shows high antibacterial activity.

  8. Synthesis, Spectroscopic, and Biological Studies on New Zirconium(IV) Porphyrins with Axial Ligand

    PubMed Central

    Bajju, Gauri D.; Devi, Gita; Katoch, Sapna; Bhagat, Madhulika; Deepmala; Ashu; Kundan, Sujata; Anand, Sunil Kumar

    2013-01-01

    A series of parasubstituted tetraphenylporphyrin zirconium(IV) salicylate complexes (SA/5-SSAZr(IV)RTPP, R = p-H, p-CH3, p-NO2, p-Cl, SA = salicylate, and 5-SSA = 5-sulfosalicylate) have been synthesized, and the spectral properties of free base porphyrins, their corresponding metallated, and axially ligated zirconium(IV) porphyrin compounds were compared with each other. A detailed analysis of ultraviolet-visible (UV-vis), proton nulcear magnetic resonance (1H NMR) spectroscopy, infrared (IR) spectroscopy, and elemental analysis suggested the transformation from free base porphyrins to zirconium(IV) porphyrins. The ability of the metal in this complex for extra coordination of solvent molecules was confirmed by ESI-MS spectra. Besides the fluorescence, cyclic voltammetry, and thermogravimetric studies, the complexes were also screened for antimicrobial and anticancer activities. Among all the complexes, 5-SSAZr(p-NO2TPP) shows high antibacterial activity. PMID:24106455

  9. Methods and intermediates for the synthesis of dipyrrin-substituted porphyrinic macrocycles

    SciTech Connect

    Yu, Lianhe; Muthukumaran, Kannan; Sreedharan, Prathapan; Lindsey, Jonathan S

    2008-02-19

    The present invention provides dipyrrin substituted porphyrinic macrocycles, intermediates useful for making the same, and methods of making the same. Such compounds may be used for purposes including the making of molecular memory devices, solar cells and light harvesting arrays.

  10. Electrical characteristic of spin coated Fe-Porphyrin on Cu substrates

    SciTech Connect

    Utari; Kusumandari,; Purnama, Budi; Mudasir; Abraha, Kamsul

    2016-06-17

    This paper describes the electrical-characteristics of Fe-Porphyrin thin films on Cu substrates. The thin layer samples used were deposited by spin coating methods on Cu-substrates at room temperature with and without induced magnetic field in the plane direction of the surface films. Fe-porphyrin was dissolved in chloroform and mixed with a magnetic stirrer for 60 min at a rotational speed of 200 rpm. The experimental results show that the mobility carrier charge of the Fe-Porphyrin layer with induced magnetic field during deposition has lower value than that without induced magnetic field case. The decrease of the mobility can be attribute to the change of the surface morphology in Fe-porphyrin films by means of increase in the nano-granular/nano-molecular size caused by the induce magnetic field.

  11. Controlled metalation of self-assembled porphyrin nanoarrays in two dimensions.

    PubMed

    Auwärter, Willi; Weber-Bargioni, Alexander; Brink, Susan; Riemann, Andreas; Schiffrin, Agustin; Ruben, Mario; Barth, Johannes V

    2007-02-02

    We report a bottom-up approach for the fabrication of metallo-porphyrin compounds and nanoarchitectures in two dimensions. Scanning tunneling microscopy and tunneling spectroscopy observations elucidate the interaction of highly regular porphyrin layers self-assembled on a Ag(111) surface with iron monomers supplied by an atomic beam. The Fe is shown to be incorporated selectively in the porphyrin macrocycle whereby the template structure is strictly preserved. The immobilization of the molecular reactants allows the identification of single metalation events in a novel reaction scheme. Because the template layers provide extended arrays of reaction sites, superlattices of coordinatively unsaturated and magnetically active metal centers are obtained. This approach offers novel pathways to realize metallo-porphyrin compounds, low-dimensional metal-organic architectures and patterned surfaces which cannot be achieved by conventional means.

  12. Chiroptical properties of an alternatingly functionalized cellotriose bearing two porphyrin groups

    USDA-ARS?s Scientific Manuscript database

    Alternatingly functionalized cellulose molecules have potential applications in optoelectronics and molecular receptors. For example, cellulose-based solar cells have been proposed. As a prototype for such molecules, the trisaccharide fragment of cellulose was modified by attachment of porphyrin gro...

  13. Charge transfer enhances two-photon absorption in transition metal porphyrins.

    PubMed

    Humphrey, Jonathan L; Kuciauskas, Darius

    2006-03-29

    Two-photon absorption processes were investigated in electropolymerized Fe(III), Mn(III), and Co(II) 5,10,15,20-tetrakis-(4-hydroxytetraphenyl)porphyrin films. Degenerate four wave mixing (DFWM) spectroscopy with 100 fs pulses in the near-IR spectral region was used. Metalloporphyrins with strong charge transfer (CT) transitions in the linear absorption spectra also show enhanced two-photon absorption. (Metalloporphyrin two-photon absorption cross section, delta, increases >10 times over that for the metal free porphyrin.) This effect was attributed to a two-photon induced charge transfer between the metal ion's d orbitals and the pi-system of the porphyrin. Correlation of one- and two-photon absorption properties of transition metal porphyrins suggests a new and simple approach to improve organic materials for photonic applications.

  14. Mn Porphyrins as Novel Molecular Magnetic Resonance Imaging Contrast Agents

    PubMed Central

    Mouraviev, Vladimir; Venkatraman, Talaignair N.; Tovmasyan, Artak; Kimura, Masaki; Tsivian, Matvey; Mouravieva, Vladimira; Polascik, Tom J.; Wang, Haichen; Amrhein, Timothy J.; Batinic-Haberle, Ines

    2012-01-01

    Abstract Background and Purpose In this study, we investigated the potential of a new class of therapeutic Mn porphyrins as molecular MRI probes for prostate cancer imaging. Two compounds of different bioavailibility were investigated: Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP5+) and Mn(III) meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTnHex-2-PyP5+). These compounds have previously been shown to have adjunctive antineoplastic activity through their actions as powerful superoxide dismutase mimics, peroxynitrite scavengers, and modulators of cellular redox-based signaling pathways. Strong paramagnetic MRI contrast properties and affinity for cancer cells suggest their potential application as novel diagnostic imaging agents. Materials and Methods MRI experiments were performed at 7.0T on a Bruker Biospec horizontal bore scanner. All in-vivo experiments were performed on 12 C57 black mice implanted with RM-9 prostate cancer cells on the hind limb. Two mg/kg of MnTnHex-2-PyP5+ (n=6) and 8 mg/kg MnTE-2-PyP5+ (n=6) were administered intraperitoneally 90 minutes before imaging. All the images were collected using a volume coil and processed using Paravision 4.0. Results Phantom studies reveal remarkably high T1 relaxivity changes for both metalloporphyrins, which are twofold to threefold higher than commercially available gadolinium chelates. Observable detection limits using conventional T1-weighted MRI are in the low micromolar range for both compounds. In vivo, MR relaxation changes in prostate tumor xenografts were readily observed after a single injection of either MnTE-2-PyP5+or MnTnHex-2-PyP5+, with tumor contrast to background ratio greatest after MnTE-2-PyP5+ administration. Conclusion After a single dose of MnTE-2-PyP5+, contrast changes in prostate tumors are up to sixfold greater than in surrounding, noncancerous tissues, suggesting the potential use of this metalloporphyrin as a novel diagnostic probe for detecting prostate

  15. Mn porphyrins as novel molecular magnetic resonance imaging contrast agents.

    PubMed

    Mouraviev, Vladimir; Venkatraman, Talaignair N; Tovmasyan, Artak; Kimura, Masaki; Tsivian, Matvey; Mouravieva, Vladimira; Polascik, Tom J; Wang, Haichen; Amrhein, Timothy J; Batinic-Haberle, Ines; Lascola, Christopher

    2012-11-01

    In this study, we investigated the potential of a new class of therapeutic Mn porphyrins as molecular MRI probes for prostate cancer imaging. Two compounds of different bioavailibility were investigated: Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP(5+)) and Mn(III) meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTnHex-2-PyP(5+)). These compounds have previously been shown to have adjunctive antineoplastic activity through their actions as powerful superoxide dismutase mimics, peroxynitrite scavengers, and modulators of cellular redox-based signaling pathways. Strong paramagnetic MRI contrast properties and affinity for cancer cells suggest their potential application as novel diagnostic imaging agents. MRI experiments were performed at 7.0T on a Bruker Biospec horizontal bore scanner. All in-vivo experiments were performed on 12 C57 black mice implanted with RM-9 prostate cancer cells on the hind limb. Two mg/kg of MnTnHex-2-PyP(5+) (n=6) and 8 mg/kg MnTE-2-PyP(5+) (n=6) were administered intraperitoneally 90 minutes before imaging. All the images were collected using a volume coil and processed using Paravision 4.0. Phantom studies reveal remarkably high T1 relaxivity changes for both metalloporphyrins, which are twofold to threefold higher than commercially available gadolinium chelates. Observable detection limits using conventional T1-weighted MRI are in the low micromolar range for both compounds. In vivo, MR relaxation changes in prostate tumor xenografts were readily observed after a single injection of either MnTE-2-PyP(5+)or MnTnHex-2-PyP(5+), with tumor contrast to background ratio greatest after MnTE-2-PyP(5+) administration. After a single dose of MnTE-2-PyP(5+), contrast changes in prostate tumors are up to sixfold greater than in surrounding, noncancerous tissues, suggesting the potential use of this metalloporphyrin as a novel diagnostic probe for detecting prostate malignancy using MRI.

  16. Light energy collection in a porphyrin-imide-corrole ensemble.

    PubMed

    Ciuciu, Adina I; Flamigni, Lucia; Voloshchuk, Roman; Gryko, Daniel T

    2013-05-01

    An assembly consisting of three units, that is, a meso-substituted corrole (C3), 1,8 naphthaleneimide (NIE), and a Zn porphyrin (ZnP), has been synthesized. NIE is connected to C3 through a 1,3-phenylene bridge and to the ZnP unit through a direct C-C bond. The convergent synthetic strategy includes the preparation of a trans-A2B-corrole possessing the imide unit, followed by Sonogashira coupling with a meso-substituted A3B-porphyrin. The photophysical processes in the resulting triad ZnP-NIE-C3 are examined and compared with those of the corresponding C3-NIE dyad and the constituent reference models C3, NIE, and ZnP. Excitation of the NIE unit in C3-NIE leads to a fast energy transfer of 98 % efficiency to C3 with a rate k(en) =7.5×10(10) s(-1), whereas excitation of the corrole unit leads to a reactivity of the excited state identical to that of the model C3, with a deactivation rate to the ground state k=2.5×10(8) s(-1). Energy transfer to C3 and to ZnP moieties follows excitation of NIE in the triad ZnP-NIE-C3. The rates are k(en) =7.5×10(10) s(-1) and k(en) =2.5×10(10) s(-1) for the sensitization of the C3 and ZnP unit, respectively. The light energy transferred from NIE to Zn porphyrin unit is ultimately funneled to the corrole component, which is the final recipient of the excitation energy absorbed by the different components of the array. The latter process occurs with a rate k(en) =3.4×10(9) s(-1) and 89 % efficiency. Energy transfer processes take place in all cases by a Förster (dipole-dipole) mechanism. The theory predicts quite satisfactorily the rate for the ZnP/C3 couple, where components are separated by about 23 Å, but results in calculated rates that are one to two orders of magnitude higher for the couples NIE/ZnP (D/A) and NIE/C3, which are separated by distances of about 14 and 10 Å, respectively. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. A strategy to design highly efficient porphyrin sensitizers for dye-sensitized solar cells.

    PubMed

    Chang, Yu-Cheng; Wang, Chin-Li; Pan, Tsung-Yu; Hong, Shang-Hao; Lan, Chi-Ming; Kuo, Hshin-Hui; Lo, Chen-Fu; Hsu, Hung-Yu; Lin, Ching-Yao; Diau, Eric Wei-Guang

    2011-08-21

    We designed highly efficient porphyrin sensitizers with two phenyl groups at meso-positions of the macrocycle bearing two ortho-substituted long alkoxyl chains for dye-sensitized solar cells; the ortho-substituted devices exhibit significantly enhanced photovoltaic performances with the best porphyrin, LD14, showing J(SC) = 19.167 mA cm(-2), V(OC) = 0.736 V, FF = 0.711, and overall power conversion efficiency η = 10.17%.

  18. An Electron Acceptor with Porphyrin and Perylene Bisimides for Efficient Non-Fullerene Solar Cells.

    PubMed

    Zhang, Andong; Li, Cheng; Yang, Fan; Zhang, Jianqi; Wang, Zhaohui; Wei, Zhixiang; Li, Weiwei

    2017-03-01

    A star-shaped electron acceptor based on porphyrin as a core and perylene bisimide as end groups was constructed for application in non-fullerene organic solar cells. The new conjugated molecule exhibits aligned energy levels, good electron mobility, and complementary absorption with a donor polymer. These advantages facilitate a high power conversion efficiency of 7.4 % in non-fullerene solar cells, which represents the highest photovoltaic performance based on porphyrin derivatives as the acceptor.

  19. Interaction of a tricationic meso-substituted porphyrin with guanine-containing polyribonucleotides of various structures

    NASA Astrophysics Data System (ADS)

    Ryazanova, Olga; Zozulya, Victor; Voloshin, Igor; Glamazda, Alexander; Dubey, Igor; Dubey, Larysa; Karachevtsev, Victor

    2016-09-01

    The interaction of a tricationic water-soluble meso-(N-methylpyridinium)-substituted porphyrin, TMPyP3+, derived from classic TMPyP4, with double-stranded poly(G)  ṡ  poly(C) and four-stranded poly(G) polyribonucleotides has been studied in aqueous buffered solutions, pH 6.9, of low and near-physiological ionic strengths in a wide range of molar phosphate-to-dye ratios (P/D). To clarify the binding modes of TMPyP3+ to biopolymers various spectroscopic techniques, including absorption and polarized fluorescence spectroscopy, Raman spectroscopy, and resonance light scattering, were used. As a result, two competitive binding modes were revealed. In solution of low ionic strength outside binding of the porphyrin to the polynucleotide backbone with self-stacking prevailed at low P/D ratios (P/D  <  3.5). It manifested itself by the substantial quenching of porphyrin fluorescence. Also the formation of large-scale porphyrin aggregates was observed near the stoichiometric binding ratio. The spectral changes observed at P/D  >  30 including emission enhancement were supposed to be caused by the embedding of partially stacked porphyrin J-dimers into the polymer groove. TMPyP3+ binding to poly(G) induced a fluorescence increase 2.5 times as large as that observed for poly(G)  ṡ  poly(C). In solution of near-physiological ionic strength the efficiency of external porphyrin binding was reduced substantially due to the competitive binding of Na+ ions with the polymer backbone. The spectroscopic characteristics of porphyrin bound to polynucleotides at different conditions were compared with those for free porphyrin.

  20. Glycoconjugates of porphyrins with carbohydrates: methods of synthesis and biological activity

    NASA Astrophysics Data System (ADS)

    Titov, D. V.; Gening, M. L.; Tsvetkov, Yu E.; Nifantiev, N. E.

    2014-06-01

    Data on the main approaches to preparation of mono- and oligodentate glycoconjugates based on porphyrin scaffolds are surveyed. The prospects for using these compounds as sensitizers for photodynamic therapy of cancer and for suppression of bacterial and viral pathogens are considered. Data on the synthesis of oligodentate blocking agents for carbohydrate-binding proteins (lectins) based on porphyrin scaffolds are discussed. The bibliography includes 161 references. Dedicated to Academician B A Trofimov on the occasion of his 75th birthday.