Photo-activated phase separation in giant vesicles made from different lipid mixtures

Autor(es)

Haluska, Christopher K. ^{[1, 2]} ; Baptista, Mauricio S. ^[3] ; Fernandes, Adjaci U. ^[3] ; Schroder, Andre P. ^[1] ; Marques, Carlos M. ^[1] ; Itri, Rosangela ^[2]

Afiliação do(s) autor(es)

^[1] Univ Strasbourg, Inst Charles Sadron, CNRS, UPR 22, F-67034 Strasbourg - France

^[2] Univ Sao Paulo, Inst Phys, Dept Appl Phys, BR-05314970 Sao Paulo - Brazil

^[3] Univ Sao Paulo, Inst Quim, Dept Bioquim, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES; v. 1818, n. 3, p. 666-672, MAR 2012.
• Citações Web of Science: 23

Resumo

Using giant unilamellar vesicles (GUVs) made from POPC. DPPC, cholesterol and a small amount of a porphyrin-based photosensitizer that we name PE-porph, we investigated the response of the lipid bilayer under visible light, focusing in the formation of domains during the lipid oxidation induced by singlet oxygen. This reactive species is generated by light excitation of PE-porf in the vicinity of the membrane, and thus promotes formation of hydroperoxides when unsaturated lipids and cholesterol are present. Using optical microscopy we determined the lipid compositions under which GUVs initially in the homogeneous phase displayed Lo-Ld phase separation following irradiation. Such an effect is attributed to the in situ formation of both hydroperoxized POPC and cholesterol. The boundary line separating homogeneous Lo phase and phase coexistence regions in the phase diagram is displaced vertically towards the higher cholesterol content in respect to ternary diagram of POPC:DPPC:cholesterol mixtures in the absence of oxidized species. Phase separated domains emerge from sub-micrometer initial sizes to evolve over hours into large Lo-Ld domains completely separated in the lipid membrane. This study provides not only a new tool to explore the kinetics of domain formation in mixtures of lipid membranes, but may also have implications in biological signaling of redox misbalance. (C) 2011 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 07/56570-9 - Christopher K. Haluska | Institut Charles Sadron - França
• Beneficiário: Rosangela Itri
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisador Visitante - Internacional