title: Mixed DPPC/DPTAP monolayers at the air/water interface: influence of indolilo-3-acetic acid and selenate ions on the monolayer morphology.
abstract: The interactions of mixed monolayers of two lipids, zwitterionic 1,2-dipalmitoyl-phosphatidylcholine (DPPC) and positively charged 1,2-dipalmitoyl-3-trimethylammonium-propane (DPTAP), with phytohormone indolilo-3-acetic acid (IAA) and selenate anions in the aqueous subphase were studied. For this purpose, isotherms of the surface pressure versus the mean molecular area were recorded. Domain formation was investigated by using Brewster angle microscopy (BAM). The method of grazing incidence X-ray diffraction (GIXD) was also applied for the characterization of the organization of lipid molecules in condensed monolayers. It was found that selenate ions contribute to monolayer condensation by neutralizing the positive net charge of mixed monolayers whereas IAA molecules penetrated the lipid monolayer, causing its expansion/fluidization. When both solutes were introduced into the subphase, a competition between them for interaction with the positively charged lipids in the monolayer was observed.
authors.affiliation: Department of Physical Chemistry and Electrochemistry, Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland. gzyl@chemia.uj.edu.pl
authors.forename: Barbara
authors.initials: B
authors.lastname: Gzyl-Malcher
authors.forename: Maria
authors.initials: M
authors.lastname: Filek
authors.forename: Gerald
authors.initials: G
authors.lastname: Brezesinski
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D000085:Acetates / Q000737:chemistry*; D000388:Air; D007211:Indoles / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008567:Membranes, Artificial; D011407:Propane / Q000031:analogs & derivatives* / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D064586:Selenic Acid; D018036:Selenium Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: C519974:1,2-dipalmitoyl-3-trimethylammonium-propane; D000085:Acetates; D007211:Indoles; D007477:Ions; D008567:Membranes, Artificial; D000644:Quaternary Ammonium Compounds; D018036:Selenium Compounds; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine; D064586:Selenic Acid; D011407:Propane