Publications

Org. Biomol. Chem. 2007, 5, 1454. 

We report the development of a new fluorescence sensor for reactive oxygen species (ROS) based on a benzofurazan structure. The sensor, NBFhd, is initially non-fluorescent and reacts with peroxyl radicals by hydrogen transfer in an aqueous medium under neutral conditions to release the fluorescent N-methyl-4-amino-7-nitrobenzofurazan (NBF) and 1,4-benzoquinone. NBFhd shows excellent contrast and no interference in the region of cell autofluorescence and is a new tool to detect ROS in homogeneous and biological systems.

Org. Biomol. Chem. 2006, 4, 802. 

We demonstrate the ability of a sensor containing a tethered fluorescein-phenol structure to react with peroxyl radicals and with an oxidizing agent such as potassium ferricyanide. This latter reaction yields the corresponding peroxyl radical as observed by EPR analysis. We propose that the reaction of the sensor with peroxyl and alkoxyl radicals is also initiated by the formation of the phenoxyl radicals, which is followed by radical-radical reactions and product hydrolysis responsible for the release of fluorescein. The proposed mechanism is based on results obtained by laser. ash photolysis, HPLC and EPR studies of the reaction of peroxyl and alkoxyl radicals with 4-phenoxylphenol, a molecule used to mimic the behavior of the sensor.

Biophysical Chemistry, 2005, 114, 53. 

Electron spin resonance (ESR) spectroscopy with nitroxide spin probes was used as a method to probe the liposome microenvironments. The effective microviscosities have been determined from the calibration of the ESR spectra of the probes in solvent mixtures of known viscosities. In the first time, by measuring ESR order parameter (S) and correlation time (tau(c)) of stearic spin probes, we have been able to quantify the value of effective microviscosity at different depths inside the liposome membrane. At room temperature, local microviscosities measured in dimyristoyl-L-alpha phosphatidylcholine (DMPC) liposome membrane at the different depths of 7.8, 16.95, and 27.7 angstrom were 222.53, 64.09, and 62.56 cP, respectively. In the gel state (10 degrees C), those microviscosity values increased to 472.56, 370.61, and 243.37 cP. In a second time, we have applied this technique to determine the modifications in membrane microviscosity induced by 2,6-d...

J. Chem. Phys. 2003, 119, 2782. 

The photoelectron spectrum of 2-furanmethanol (furfuryl alcohol) has been measured for ionization energies between 8 and 11.2 eV and the first three ionization bands assigned to π3,π3, π2,π2, and nono ionizations in order of increasing binding energy. The photoabsorption spectrum has been recorded in the gas phase using both a synchrotron radiation source (5–9.91 eV, 248–125 nm) and electron energy-loss spectroscopyunder electric-dipole conditions (5–10.9 eV, 248–90 nm). The (UV) absorption spectrum has also been recorded in solution (4.2–6.36 eV, 292–195 nm). The electronic excitation spectrumappears to be dominated by transitions between π and π*orbitals in the aromatic ring, leading to the conclusion that the frontier molecular orbitals of furan are affected only slightly on replacement of a H atom by the –CH2OH–CH2OH group. Additional experiments investigating electron impact at near-threshold energies have revealed two low-lying triplet states and a...

Photochem. Photobiol. Sci. 2003, 2, 939. 

The reaction between the anaesthetic agent 2,6-diisopropylphenol ( propofol, PPF) and singlet oxygen (O-1(2)) has been investigated in aqueous solution by means of HPLC, GC, absorption spectroscopy and laser. ash photolysis with infrared luminescence detection. The rate constants for the physical and chemical quenching of O-1(2) by PPF (k(PPF)) are found to be 2.66 x 10(5) M-1 s(-1) and similar to3.2 x 10(6) M-1 s(-1) in CD3OD and D2O - CD3OD (75: 25 v/v), respectively. The reaction of propofol with singlet oxygen produced by light irradiation of Rose Bengal leads essentially to two reaction products, 2,6-diisopropyl-p-benzoquinone and 3,5,3', 5'-tetraisopropyl-(4,4')-diphenoquinone that are unambiguously identified from comparison with authentic samples.

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