Determination of the singlet oxygen quantum yield of bacteriochlorin a: a comparative study in phosphate buffer and aqueous dispersion of dimiristoyl-L-a-phosphatidylcholine liposomes

in Photochemical & Photobiological Sciences (2002), 1(4), 283-287

The production of singlet oxygen (1O2) by bacteriochlorin a (BCA) was studied in phosphate buffer and in dimyristoyl-L-α-phosphatidylcholine (DMPC) unilamellar liposomes. The comparative method used to ... [more ▼]

The production of singlet oxygen (1O2) by bacteriochlorin a (BCA) was studied in phosphate buffer and in dimyristoyl-L-α-phosphatidylcholine (DMPC) unilamellar liposomes. The comparative method used to measure 1O2 production was a quantitative analysis of photooxidation reactions leading to the loss of absorbance of the water-soluble specific probe: anthracene 9,10-dipropionic acid. Rose Bengal, whose 1O2 quantum yield (ΦRB) is well known in alcohols and phosphate buffer, was used as the standard for the quantification of the BCA singlet oxygen production. Our results confirm quantitatively that solubilization of BCA in liposomes leads to an increase in 1O2 production. Indeed, the quantum yield of 1O2 production by BCA (ΦBCA) is 0.05 in phosphate buffer and 0.33 in DMPC liposomes. Furthermore, the diffusion characteristics of 1O2 produced by BCA bound to liposome were also examined using the isotopic lifetime enhancement effect of D2O. It was shown that 1O2 spent at least 70% of its lifetime in the vesicular environment [less ▲]

New method for nitroxyl radical synthesis

Conference (2002)

Physique expérimentale préparatoire aux sciences biomédicales y compris l'introduction mathématique aux sciences expérimentales : Fascicule de travaux dirigés

Learning material (2002)

Increase of the Photosensitizing Efficiency of the Bacteriochlorin a by Liposome-Incorporation

in Journal of Photochemistry & Photobiology B : Biology (2001), 60(1), 50-60

To describe the action mechanisms of Bacteriochlorin a (BCA), a second generation photosensitizer, in phosphate buffer (PB) and in dimyristoyl phosphatidylcholine (DMPC) liposomes we carried out oxygen ... [more ▼]

To describe the action mechanisms of Bacteriochlorin a (BCA), a second generation photosensitizer, in phosphate buffer (PB) and in dimyristoyl phosphatidylcholine (DMPC) liposomes we carried out oxygen consumption and ESR measurements. In PB, where BCA was in a monomer-dimer equilibrium, our results suggested that the oxygen consumption was related to the BCA monomers concentration in solution. Incorporation of BCA in DMPC liposomes, by promoting the monomerization of BCA, increased 9-fold the oxygen consumption in comparison to the value in PB. The use of specific singlet oxygen quenchers (Azide and 9,10-Anthracenedipropionic acid) in ESR and oxygen consumption experiments allowed us to assert that BCA was mainly a type II sensitizer when it was incorporated in DMPC. Finally, the cell survival of WiDr cells after a PDT treatment was measured for cells incubated with BCA in cell culture medium and cells incubated with BCA in DMPC. Irrespective of the dye concentration, the cell survival was lower when liposomes were used. This effect could be the result of a better BCA monomerization and/or a different BCA uptake in cells. [less ▲]

Increase of the bacteriochlorin a photosensitizing properties by incorporation within DMPC in liposomes

Conference (2001)

Increase of the photosensitizing efficiency of the Bacteriochlorin a by liposome-incorporation

in Journal of Photochemistry & Photobiology B : Biology (2001), 60

To describe the action mechanisms of Bacteriochlorin a (BCA), a second generation photosensitizer, in phosphate buffer (PB) and in dimyristoyl phosphatidylcholine (DMPC) liposomes we carried out oxygen ... [more ▼]

To describe the action mechanisms of Bacteriochlorin a (BCA), a second generation photosensitizer, in phosphate buffer (PB) and in dimyristoyl phosphatidylcholine (DMPC) liposomes we carried out oxygen consumption and ESR measurements. In PB, where BCA was in a monomer–dimer equilibrium, our results suggested that the oxygen consumption was related to the BCA monomers concentration in solution. Incorporation of BCA in DMPC liposomes, by promoting the monomerization of BCA, increased 9-fold the oxygen consumption in comparison to the value in PB. The use of specific singlet oxygen quenchers (Azide and 9, 10-Anthracenedipropionic acid) in ESR and oxygen consumption experiments allowed us to assert that BCA was mainly a type II sensitizer when it was incorporated in DMPC. Finally, the cell survival of WiDr cells after a PDT treatment was measured for cells incubated with BCA in cell culture medium and cells incubated with BCA in DMPC. Irrespective of the dye concentration, the cell survival was lower when liposomes were used. This effect could be the result of a better BCA monomerization and/or a different BCA uptake in cells [less ▲]

Le propofol agent anesthésique et agent antioxydant? Une étude spectroscopique des propriétés inhibitrices du propofol vis-à-vis de l'oxygène singulet

Conference (2000)

Applications biomédicales de la RPE

Scientific conference (1999, December)

A spectroscopic study inside liposomes of propofol singlet oxygen quenching properties

Conference (1999)

Increase of the bacteriochlorin a photosensitizing efficiency by incorporation in liposomes

Conference (1999)