Fluorescence, absorption and electron spin resonance study of bacteriochlorin a incorporation into membrane models

Hoebeke, Maryse; Damoiseau, Xavier; Schuitmaker, Hans J.; Vorst, A. Van de

doi:10.1016/s0005-2736(99)00097-8

Cited by 14 publications

(28 citation statements)

References 33 publications

(35 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general, incorporation of a dye in liposomes led to an increase of the fluorescence intensity in comparison with its intensity in aqueous solutions. This increase was studied as a function of the lipid concentration at constant PPME concentration (2.5 µM) in order to establish the ratio between lipids and dye at which all PPME in suspension may be considered as bound to liposomes 33 . Fig.…”

Section: Determination Of Ppme Incorporation Limit In Liposomesmentioning

confidence: 99%

Physical and chemical properties of pyropheophorbide-a methyl ester in ethanol, phosphate buffer and aqueous dispersion of small unilamellar dimyristoyl-l-α-phosphatidylcholine vesicles

Delanaye

Bahri

Tfibel

et al. 2006

Photochem Photobiol Sci

Self Cite

View full text Add to dashboard Cite

This submission was created using the RSC Article Template (DO NOT DELETE THIS TEXT) (LINE INCLUDED FOR SPACING ONLY -DO NOT DELETE THIS TEXT)The aggregation process of pyropheophorbide-a methyl ester (PPME), a second generation photosensitizer, was investigated in various solvents. Absorption and fluorescence spectra showed that the photosensitizer was under a monomeric form in ethanol as well as in dimyristoyl-L-α-phosphatidylcholine liposomes while it was strongly aggregated in phosphate buffer. A quantitative determination of reactive oxygen species production by PPME in these solvents has been undertaken by electron spin resonance associated with spin trapping technique and absorption spectroscopy. In phosphate buffer, both electron spin resonance and absorption measurements led to the conclusion that singlet oxygen production was not detectable while hydroxyl radical production was very weak. In liposomes and ethanol, singlet oxygen and hydroxyl radical production increased highly; the singlet oxygen quantum yield was determined to be 0.2 in ethanol and 0.13 in liposomes. The hydroxyl radical production origin was also investigated. Singlet oxygen was formed from PPME triplet state deactivation in presence of oxygen. Indeed, the triplet state formation quantum yield of PPME was found to be about 0.23 in ethanol, 0.15 in liposomes (too small to be measured in PBS).

show abstract

Section: Determination Of Ppme Incorporation Limit In Liposomesmentioning

confidence: 99%

Physical and chemical properties of pyropheophorbide-a methyl ester in ethanol, phosphate buffer and aqueous dispersion of small unilamellar dimyristoyl-l-α-phosphatidylcholine vesicles

Delanaye

Bahri

Tfibel

et al. 2006

Photochem Photobiol Sci

Self Cite

View full text Add to dashboard Cite

show abstract

“…It has also been shown that solubilization of BCA in liposomes induces dye monomerization. 11 Oxygen consumption measurements carried out with a Clarke electrode in water and in liposome solutions indicate that the production of 1 O 2 is strongly influenced by the dye aggregation state since it seems that only the monomeric species is appreciably photoactive. 12 Indeed, monomerization of BCA by solubilization within liposomes increases the PDT activity and is accompanied by an enhancement of singlet oxygen production.…”

Section: Introductionmentioning

confidence: 99%

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

Hoebeke

Damoiseau

2002

Photochem Photobiol Sci

Self Cite

View full text Add to dashboard Cite

The production of singlet oxygen ( 1 O 2 ) by bacteriochlorin a (BCA) was studied in phosphate buffer and in dimyristoyl--α-phosphatidylcholine (DMPC) unilamellar liposomes. The comparative method used to measure 1 O 2 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 1 O 2 quantum yield (Φ RB ) 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 1 O 2 production. Indeed, the quantum yield of 1 O 2 production by BCA (Φ BCA ) is 0.05 in phosphate buffer and 0.33 in DMPC liposomes.Furthermore, the diffusion characteristics of 1 O 2 produced by BCA bound to liposome were also examined using the isotopic lifetime enhancement effect of D 2 O. It was shown that 1 O 2 spent at least 70% of its lifetime in the vesicular environment.

show abstract

“…The medium where BCA is solubilized influences not only the 1 O 2 production but also the dye aggregation properties (8). In methanol, BCA is monomeric, and no aggregation is observed below 5 3 10 25 M (8). In phosphate buffer (pH 7), BCA is strongly aggregated in its dimeric form.…”

Section: Introductionmentioning

confidence: 99%

“…In phosphate buffer (pH 7), BCA is strongly aggregated in its dimeric form. The dimerization constant was estimated to be 10 6 M 21 (7,8). The solubilization of BCA within DMPC liposomes induces dye monomerization.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Aggregation on Bacteriochlorin a Triplet-state Formation: A Laser Flash Photolysis Study¶

Damoiseau¹,

Tfibel²,

Hoebeke³

et al. 2002

Photochem Photobiol

Self Cite

View full text Add to dashboard Cite

Bacteriochlorin a (BCA) is a potential photosensitizer for photodynamic therapy of cancer. It has been shown previously that the photoefficiency of the dye is mainly dependent on singlet oxygen (1O2) generation. Nanosecond laser flash photolysis was used to produce and to investigate the excited triplet state of the dye in methanol, phosphate buffer and dimiristoyl-L-alpha-phosphatidylcholine (DMPC) liposomes. The transients were characterized in terms of their absorption spectra, decay kinetics, molar absorption coefficients and formation quantum yield of singlet-triplet intercrossing. The lifetime of the BCA triplet state was measured at room temperature. The triplet-state quantum yield is quite high in methanol (0.7) and in DMPC (0.4) but only 0.095 in phosphate buffer. In the last case, BCA is in a monomer-dimer equilibrium, and the low value of the quantum yield observed was ascribed to the fact the triplet state is only formed by the monomers.

show abstract

Fluorescence, absorption and electron spin resonance study of bacteriochlorin a incorporation into membrane models

Cited by 14 publications

References 33 publications

Physical and chemical properties of pyropheophorbide-a methyl ester in ethanol, phosphate buffer and aqueous dispersion of small unilamellar dimyristoyl-l-α-phosphatidylcholine vesicles

Physical and chemical properties of pyropheophorbide-a methyl ester in ethanol, phosphate buffer and aqueous dispersion of small unilamellar dimyristoyl-l-α-phosphatidylcholine vesicles

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

Effect of Aggregation on Bacteriochlorin a Triplet-state Formation: A Laser Flash Photolysis Study¶

Contact Info

Product

Resources

About