title: Characterization of planar biomimetic lipid films composed of phosphatidylethanolamines and phosphatidylglycerols from Escherichia coli.
abstract: We have characterized planar lipid films composed of phosphatidylethanolamines (PE) and phosphatidylglycerols (PG) from E. coli bacteria. The nature of the interactions and miscibility of PE and PG components within mixed lipid films was evaluated based on surface pressure measurements and Brewster angle microscopy imaging at the air-water interface. We have found that PE and PG components show tendency to form separated domains at surface pressures relevant for biological membranes. Further, we have directly compared mechanisms of formation of supported lipid bilayers either on mica or Au(111) by spreading of small unilamellar vesicles. The bilayer formation was monitored by in situ atomic force microscopy imaging. The pathways of the vesicles spreading on each substrate are substantially different and the buildup of the bilayer on Au(111) occurs through complex multistep mechanism. The morphology and nanomechanical properties of the resulting PE/PG bilayers were thoroughly compared. We have found that the interactions between lipids and supporting substrate significantly affect molecular organization within the films since the bilayer on Au(111) is uniform in terms of the topography, while the same lipid composition on mica results in formation of distinct gel and liquid disordered domains. Different molecular organization affects also nanomechanical properties of lipid films. The latter were expressed in terms of Young's moduli and bending stiffness.
authors.affiliation: Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Konarzewska
authors.affiliation: Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Juhaniewicz
authors.affiliation: Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland.
authors.forename: Alişan
authors.initials: A
authors.lastname: Güzeloğlu
authors.affiliation: Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland. Electronic address: slasek@chem.uw.edu.pl.
authors.forename: Sławomir
authors.initials: S
authors.lastname: Sęk
mesh_terms: D000388:Air; D000538:Aluminum Silicates / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry*; D055119:Elastic Modulus; D004926:Escherichia coli / Q000378:metabolism*; D006046:Gold / Q000737:chemistry; D018625:Microscopy, Atomic Force; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D010715:Phosphatidylglycerols / Q000737:chemistry*; D053835:Unilamellar Liposomes / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D001672:Biocompatible Materials; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D053835:Unilamellar Liposomes; D014867:Water; D006046:Gold; C011934:mica
keywords: Adsorption; Atomic force microscopy; Bilayer; Lipids; Surface pressure