Giant Vesicles under Oxidative Stress Induced by a Membrane-Anchored Photosensitizer

We have synthesized the amphiphile photosensitizer PE-porph consisting of a porphyrin bound to a lipid headgroup. We studied by optical microscopy the response to light irradiation of giant unilamellar vesicles of mixtures of unsaturated phosphatidylcholine lipids and PE-porph. In this configuration...

Full description

Saved in:
Bibliographic Details
Published in:Biophysical journal 2009-09, Vol.97 (5), p.1362-1370
Main Authors: Riske, Karin A., Sudbrack, Tatiane P., Archilha, Nathaly L., Uchoa, Adjaci F., Schroder, André P., Marques, Carlos M., Baptista, Maurício S., Itri, Rosangela
Format: Article
Language:English
Subjects:
Computer Simulation
Fluorescence
Light
Lipid Bilayers - chemistry
Lipid Bilayers - radiation effects
Lipids
Membrane
Membranes
Microscopy, Fluorescence
Models, Chemical
Molecules
Oxidative Stress
Oxygen
Oxygen - chemistry
Phosphatidylcholines - chemistry
Phosphatidylcholines - radiation effects
Phosphatidylethanolamines - chemistry
Phosphatidylethanolamines - radiation effects
Photosensitizing Agents - chemistry
Photosensitizing Agents - radiation effects
Porphyrins - chemistry
Porphyrins - radiation effects
Simulation
Time Factors
Unilamellar Liposomes - chemistry
Unilamellar Liposomes - radiation effects
VOCs
Volatile organic compounds
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We have synthesized the amphiphile photosensitizer PE-porph consisting of a porphyrin bound to a lipid headgroup. We studied by optical microscopy the response to light irradiation of giant unilamellar vesicles of mixtures of unsaturated phosphatidylcholine lipids and PE-porph. In this configuration, singlet oxygen is produced at the bilayer surface by the anchored porphyrin. Under irradiation, the PE-porph decorated giant unilamellar vesicles exhibit a rapid increase in surface area with concomitant morphological changes. We quantify the surface area increase of the bilayers as a function of time and photosensitizer molar fraction. We attribute this expansion to hydroperoxide formation by the reaction of the singlet oxygen with the unsaturated bonds. Considering data from numeric simulations of relative area increase per phospholipid oxidized (15%), we measure the efficiency of the oxidative reactions. We conclude that for every 270 singlet oxygen molecules produced by the layer of anchored porphyrins, one eventually reacts to generate a hydroperoxide species. Remarkably, the integrity of the membrane is preserved in the full experimental range explored here, up to a hydroperoxide content of 60%, inducing an 8% relative area expansion.
ISSN:0006-3495
1542-0086
DOI:10.1016/j.bpj.2009.06.023