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Physical damage on model membranes promoted by photosensitization

Grant number: 14/02511-5
Support type:Scholarships in Brazil - Doctorate (Direct)
Effective date (Start): April 01, 2014
Effective date (End): December 31, 2017
Field of knowledge:Biological Sciences - Biophysics - Molecular Biophysics
Principal researcher:Rosangela Itri
Grantee:Raffaela de Rosa
Home Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated research grant:12/50680-5 - Photosensitization in life sciences, AP.TEM


Studying photosensitized oxidation of unsaturated phospholipids is of importance for understanding the basic processes underlying photodynamic therapy, photoaging and many other biological disfunctions. In this project we will use large unilamellar vesicles as simplified models of biological membranes, to investigate how in situ photogenerated oxidative species impart on the phospholipid bilayer. The extent of membrane damage can be modulated by choosing a specific photosensitizer, PS, which is activated by light irradiation and can react by either type I and or type II mechanism. The type II PS generates only singlet oxygen which reacts to the phospholipid acyl double bond. The formed byproduct is a lipid hydroperoxide which accumulates in the membrane as a function of singlet oxygen production and induces an increase in its area without affecting significantly the membrane permeability. The presence of a lipid hydroperoxide can also play an important role in the lipid domain formation for mimetic plasma membranes. Lipid hydroperoxides can be also transformed in shortened chain compounds as aldehydes, carboxylic acids, for instance, in the presence of a PS that reacts via type I mechanism. The presence of such byproducts may form hydrophilic pores in the membrane for moderate oxidative stress or promote membrane disruption for massive oxidation. In the current project, we will focus on the changes imparted by photosentitization on model membranes by analyzing the structural modification on the lipid bilayer by SAXS and fluidity by EPR. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
DE ROSA, RAFFAELA; SPINOZZI, FRANCESCO; ITRI, ROSANGELA. Hydroperoxide and carboxyl groups preferential location in oxidized biomembranes experimentally determined by small angle X-ray scattering: Implications in membrane structure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES, v. 1860, n. 11, p. 2299-2307, NOV 2018. Web of Science Citations: 6.

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