Lyoluminescence and spin trapping

Ettinger, K.V.; Forrester, A. R.; Hunter, Charles

doi:10.1139/v82-502

Cited by 31 publications

(4 citation statements)

References 4 publications

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“…To confirm the later process upon light irradiation, we performed ESR-ST experiments: the carbon-centered radical (•CH 2 COOH) generated by the homolytic C–S single bond cleavage is well observed (Figure B): the hyperfine coupling constants of the carbon radical adduct (aN = 14.6 G, aH = 4.4 G) are in agreement with the literature data . It should be pointed out that the experimental data (Figure B-1) are in excellent agreement with the simulated results (Figure B-2).…”

Section: Resultssupporting

confidence: 79%

Photoactivable Surface of Natural Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) for Antiadhesion Applications

Poupart

Haider

Babinot

et al. 2015

ACS Biomater. Sci. Eng.

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A green photoinduced method for the modification of a biodegradable and biocompatible polymer, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) has been successfully carried out using two types of monomers with potential antibacterial effects, i.e. 2-[(methacryloyloxy)-ethyl] trimethylammonium chloride (META) and an ampicillin-derived monomer. The photografting process is conducted through a photoinduced free-radical process employing a thiocarbamate-based photoinitiator in an aqueous medium. Under appropriate conditions, radicals are generated from the PHBHV surface, thus initiating the UV-mediated photopolymerization of methacrylate or methylacrylamide-derived monomers from the surface of PHBHV films. The photochemical mechanism of the thiocarbamate photolysis is entirely described by the Electron Spin Resonance / Spin-Trapping technique and Laser Flash Photolysis, and the modified-PHBHV films are extensively characterized by fluorescence experiments, water contact angle and XPS measurements. Finally, a primary investigation is conducted to support the antibacterial property of the new functionalized films against Escherichia coli and Staphylococcus aureus, and their cytocompatibility with NIH-3T3 fibroblastic cells is evaluated.

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Section: Resultssupporting

confidence: 79%

Photoactivable Surface of Natural Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) for Antiadhesion Applications

Poupart

Haider

Babinot

et al. 2015

ACS Biomater. Sci. Eng.

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“…Although there have been few reports of its use certain olefins. Because the spin adducts a (1 [1][2][3][4][5][6][7][8][9][10][11][12][13][14], the synthesis of 1 is inexpensive and easy and, unlike , erately wide range of values forthe splitting constants a p -~( c H ) other nitroso compounds frequently employed (3-5) as spin and a , .~, which vary with the nature of the radical trapped, it traps, 1 is insensitive to laboratory light.…”

Section: Introductionmentioning

confidence: 99%

Electron paramagnetic resonance study of the reactions of the spin trap 3,5-dibromo-4-nitrosobenzenesulfonate

Smith¹,

Robertson²

1988

Can. J. Chem.

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PETER SMITH and JILL SUZANNE ROBERTSON. Can. J. Chem. 66, 1 153 (1988). Using rapid-mixing, continuous-flow TiCI3-based techniques and also by means of static-sample studies involving the thermal decomposition of symmetric aliphatic azo compounds, we have characterized by electron paramagnetic resonance 22 spin adducts of 3,5-dibromo-4-nitrosobenzenesulphonate, 1, in aqueous solution at 25'C. These spin adducts, all nitroxides, exhibit a moderately wide range of a-nitrogen and P-CH proton splitting constants, which we discuss in terms of steric and electronic effects. In connection with these studies, blank experiments showed that aqueous solutions of 1 gave no radicals when exposed to light and heat. In addition, we have studied by electron paramagnetic resonance at 25OC static samples of aqueous solutions of 1 both by itself and in the presence of each of several acrylic and methacrylic monomers and in both the presence and absence of light. These solutions yielded radicals, namely, nitroxides, only when containing methacrylic monomers, the presence of light having no effect. These observations support the "ene" addition/oxidation mechanism of nitroxide formation.PETER SMITH et JILL SUZANNE ROBERTSON. Can. J. Chem. 66, 1 153 (1988). OpCrant en solutions aqueuses, a 25"C, faisant appel a la resonance paramagnetique Clectronique et utilisant des techniques de mClange rapide, flux continu et basCes sur le TiCI3 ainsi que des Ctudes a l'aide dlCchantillons statiques impliquant la dtcomposition thermique de composCs azo aliphatiques symktriques, on a caracterist 22 adduits de spin du dibromo-3,5 nitroso-4 sulfonate, 1. Ces adduits de spin, tous des nitroxydes, prCsentent tous un Cventail assez large de constantes de couplages avec l'azote en a et le proton CH en P. Pour fins de comparaison, on a demontrC que des solutions aqueuses ne contenant que du composC 1 ne donnent pas de radicaux lorsqu'on les expose a la lumiere ou a la chaleur. De plus, operant a 25°C et faisant appel a la resonance paramagnetique electronique, on a CtudiC dans tchantillons statiques du compost5 1, en solutions aqueuses, soit seul ou en prCsence de plusieurs monomeres acryliques et mkthacryliques diffkrents, tant en prtsence qu'en absence de lumitres. Ces solutions ne fournissent des radicaux, soit des nitroxydes, que lorsqu'elles contiennent des monomeres mtthacryliques; la prCsence de lumiere est sans effet. Ces rtsultats suggerent que la formation du nitroxyde implique un mCcanisme d'addition/oxydation de nature ccene,.[Traduit par la revue]

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“…At a DMPO concentration of 400 mM, the spectra in all cases were dominated by the signal from the DMPO/ • O t Bu adduct (Figures A, 3A, and 4A). In addition, the spectrum obtained in the presence of Gly-Gly-Gly contained weak signals from an additional species, which is most likely an adduct of a radical derived from the peptide (Figure A) . In the absence of the peptides, lowering the spin-trap concentration resulted in a marked increase in the relative intensity of the DMPO/ • OMe adduct, which became the dominant species at 20 mM DMPO.…”

Section: Resultsmentioning

confidence: 98%

EPR Spin-Trapping Evidence for the Direct, One-Electron Reduction oftert-Butylhydroperoxide to thetert-Butoxyl Radical by Copper(II): Paradigm for a Previously Overlooked Reaction in the Initiation of Lipid Peroxidation

Jones

Burkitt

2003

J. Am. Chem. Soc.

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Lipid peroxidation is often initiated using Cu(II) ions. It is widely assumed that Cu(II) oxidizes preformed lipid hydroperoxides to peroxyl radicals, which propagate oxidation of the parent fatty acid via hydrogen atom abstraction. However, the oxidation of alkyl hydroperoxides by Cu(II) is thermodynamically unfavorable. An alternative means by which Cu(II) ions could initiate lipid peroxidation is by their one-electron reduction of lipid hydroperoxides to alkoxyl radicals, which would be accompanied by the generation of Cu(III). We have investigated by EPR spectroscopy, in conjunction with the spin trap 5,5-dimethyl-1-pyrroline N-oxide, the reactions of various Cu(II) chelates with tert-butylhydroperoxide. Spectra contained signals from the tert-butoxyl, methyl, and methoxyl radical adducts. In many previous studies, the signal from the methoxyl adduct has been assigned incorrectly to the tert-butylperoxyl adduct, which is now known to be unstable, releasing the tert-butoxyl radical upon decomposition. This either is trapped by 5,5-dimethyl-1-pyrroline N-oxide or undergoes beta-scission to the methyl radical, which either is trapped or reacts with molecular oxygen to give, ultimately, the methoxyl radical adduct. By using metal chelates that are known to be specific in either their oxidation or reduction of tert-butylhydroperoxide (the Cu(II) complex of bathocuproine disulfonic acid and the Fe(II) complex of diethylenetriaminepentaacetic acid, respectively) for comparison, we have been able to deduce, from the relative concentrations of the three radical adducts, that the Cu(II) complexes tested each reduce tert-butylhydroperoxide directly to the tert-butoxyl radical. These findings suggest that a previously overlooked reaction, namely the direct reduction of preformed lipid hydroperoxides to alkoxyl radicals by Cu(II), may be responsible for the initiation of lipid peroxidation by Cu(II) ions.

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Lyoluminescence and spin trapping

Cited by 31 publications

References 4 publications

Photoactivable Surface of Natural Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) for Antiadhesion Applications

Photoactivable Surface of Natural Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) for Antiadhesion Applications

Electron paramagnetic resonance study of the reactions of the spin trap 3,5-dibromo-4-nitrosobenzenesulfonate

EPR Spin-Trapping Evidence for the Direct, One-Electron Reduction oftert-Butylhydroperoxide to thetert-Butoxyl Radical by Copper(II): Paradigm for a Previously Overlooked Reaction in the Initiation of Lipid Peroxidation

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