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Study of the fusion mechanism of fusogenic cationic liposomes using advanced optical microscopy tools

Grant number: 18/08014-4
Support type:Scholarships abroad - Research Internship - Doctorate (Direct)
Effective date (Start): September 01, 2018
Effective date (End): August 31, 2019
Field of knowledge:Biological Sciences - Biophysics - Molecular Biophysics
Principal Investigator:Karin Do Amaral Riske
Grantee:Rafaela Ramos Mororó Cavalcanti
Supervisor abroad: Rumiana Dimova
Home Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
Local de pesquisa : Max Planck Society, Munich, Germany  
Associated to the scholarship:17/09367-5 - Study of the fusion mechanism of cationic fusogenic liposomes and their potential as carrier system, BP.DD

Abstract

Liposomes are reliable biomimetic models of the complex biological membrane and have a great potential as drug delivery systems. Fusogenic liposomes, based on cationic (e.g. DOTAP) and fusion promoter (e.g. DOPE) lipids, are interesting delivery systems because of their effective intracellular delivery of encapsulated materials, in comparison with conventional liposomes that usually undergo ineffective endocytic routes to enter the cells. To better understand the fusion efficiency and mechanism of such systems, we intend to study the fusion between cationic liposomes and Giant Unilamellar Vesicles (GUVs) as biomimetic models of cells. Based on systems with proven fusion efficiency, we intend in this project to vary the lipid composition of both fusogenic and acceptor membranes in order to understand the role of membrane organization and phase state in the fusion mechanism and efficiency using advanced optical microscopy and micromanipulation tools. More specifically, cholesterol-containing membranes, and membranes in the gel, liquid-ordered and liquid-disordered phases will be explored. These experiments will be conducted at the Max Planck Institute of Colloids and Interfaces in Germany, in a lab that is a world reference in advanced optical microscopy-based tools applied to GUVs to study membrane Biophysics. Especially, the use of a confocal microscope, fluorescence lifetime imaging microscopy (FLIM) and a high temporal resolution camera will allow: quantification of the fusion efficiency between fusogenic liposomes and acceptor GUVs using fluorescence resonance energy transfer (FRET) assays and micropipette aspiration approach; and measurement of the edge tension, diffusion coefficient and bending modulus of selected lipid compositions. Together, this information will clarify the role of lipids and membrane phase state in the membrane fusion process and will help develop more efficient drug delivery systems based on fusogenic liposomes that will later on be tested with different cell lines. (AU)