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Photo-oxidation of Langmuir films as mimetic systems of Escherichia coli membrane

Grant number: 18/13021-0
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): September 01, 2018
Effective date (End): August 31, 2020
Field of knowledge:Physical Sciences and Mathematics - Physics
Principal Investigator:Pedro Henrique Benites Aoki
Grantee:Lucas Gontijo Moreira
Home Institution: Faculdade de Ciências e Letras (FCL-ASSIS). Universidade Estadual Paulista (UNESP). Campus de Assis. Assis , SP, Brazil
Associated scholarship(s):19/20853-4 - Eosin decyl ester binding and photo-oxidation effects on simplified models of bacterial membrane based on giant unilamellar vesicles, BE.EP.IC


The photodynamic inactivation of microorganisms (PDIM) has received considerable attention due to the efficiency against the super-resistance of bacteria. The technique is based on the controlled administration of a photosensitizer (FS), subsequently photoactivated for the generation of reactive oxygen species (ROS), responsible for the inactivation of microorganisms. It is known that the unsaturated phospholipids present in cell membranes are the main targets of ROS. However, the mechanisms of interaction with FSs as well the effects of lipid oxidation over the membrane properties are not yet fully understood. In this project, Langmuir monolayers will be used to mimic the lipid membrane of Escherichia coli, an important pathogen that has acquired resistance to antibiotics. For this purpose, ultrathin films of the unsaturated phospholipids 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE), 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol)(sodium salt) (DOPG) and cardiolipin (CA) will be made in ultrapure water subphase, containing different concentrations of eosine decyl ester (EosDec). The EosDec incorporated into the membrane will be further photoactivated in order to evaluate the effects of lipid oxidation on the physical-chemical properties of the membrane, which include the increase of the mean molecular area occupied by the lipids and the cleavage of the carbon chains. This scientific initiation project is conceived within the research line of the Fapesp regular project 2016/13280-0 in development at the Department of Biotechnology of FCL / UNESP, Assis.