title: An EXAFS study of the binding of Cd and Pb ions to lipid films.
abstract: Extended X-ray Absorption Fine Structure (EXAFS) measurements performed on Langmuir-Blodgett (LB) films containing cadmium and lead ions reveal the different coordination structures of the two cations in lipid membranes. We describe the local atomic environment of cadmium and lead in LB films prepared with stearic and 1,2 distearoyl-Lα-phosphatidic acids. The measurements have been performed on films of two different thicknesses, one and seven molecular layers, and at two different values of relative humidity. The local atomic environment of Cd ions in stearate films is consistent with unidentate coordination in which a Cd ion binds two stearate molecules, while that of Pb ions is consistent with a bidentate coordination in which a Pb ion binds one stearate molecule. Furthermore, in lead stearate films, there is Pb-Pb coordination as already observed in Langmuir films. In films of Pb-phosphatidic acid, oxygen atoms of the organic phosphate and oxygen atoms of bound water form two distinct shells.
authors.affiliation: Department of Physics, University of Genoa, Genoa, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bergamino
authors.forename: Annalisa
authors.initials: A
authors.lastname: Relini
authors.forename: Pasquale
authors.initials: P
authors.lastname: Rispoli
authors.forename: Lisa
authors.initials: L
authors.lastname: Giachini
authors.forename: Francesco
authors.initials: F
authors.lastname: d'Acapito
authors.forename: Ranieri
authors.initials: R
authors.lastname: Rolandi
mesh_terms: D002104:Cadmium / Q000737:chemistry; D007854:Lead / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D013228:Stearates / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
chemical_list: D008051:Lipid Bilayers; D013228:Stearates; D002104:Cadmium; D007854:Lead
references.citation: Chem Phys Lipids. 2002 May;115(1-2):39-61
references.pmid: 12047897
references.citation: Environ Sci Technol. 2009 Jan 1;43(1):94-100
references.pmid: 19209590
references.citation: J Phys Chem B. 2010 Jul 29;114(29):9485-95
references.pmid: 20614879
references.citation: J Synchrotron Radiat. 2003 May 1;10(Pt 3):260-4
references.pmid: 12714758
references.citation: Environ Microbiol. 2007 Feb;9(2):308-21
references.pmid: 17222130
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Apr;83(4 Pt 1):041604
references.pmid: 21599172
references.citation: J Am Chem Soc. 2002 Aug 14;124(32):9412-21
references.pmid: 12167036
references.citation: J Synchrotron Radiat. 2001 Mar 1;8(Pt 2):96-100
references.pmid: 11512993
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Oct;84(4 Pt 1):041601
references.pmid: 22181145
references.citation: Science. 1993 Jul 23;261(5120):449-52
references.pmid: 8392751
references.citation: Langmuir. 2010 Dec 21;26(24):18951-8
references.pmid: 21114263
references.citation: J Synchrotron Radiat. 2001 Mar 1;8(Pt 2):946-8
references.pmid: 11512988
references.citation: J Synchrotron Radiat. 2005 Jul;12(Pt 4):537-41
references.pmid: 15968136
references.citation: Phys Rev B Condens Matter. 1988 Jul 15;38(2):1016-1026
references.pmid: 9946354