title: Assembly and structure of alpha-helical peptide films on hydrophobic fluorocarbon surfaces.
abstract: The structure, orientation, and formation of amphiphilic alpha-helix model peptide films on fluorocarbon surfaces has been monitored with sum frequency generation (SFG) vibrational spectroscopy, near-edge x-ray absorption fine structure (NEXAFS) spectroscopy, and x-ray photoelectron spectroscopy (XPS). The alpha-helix peptide is a 14-mer of hydrophilic lysine and hydrophobic leucine residues with a hydrophobic periodicity of 3.5. This periodicity yields a rigid amphiphilic peptide with leucine and lysine side chains located on opposite sides. XPS composition analysis confirms the formation of a peptide film that covers about 75% of the surface. NEXAFS data are consistent with chemically intact adsorption of the peptides. A weak linear dichroism of the amide pi( *) is likely due to the broad distribution of amide bond orientations inherent to the alpha-helical secondary structure. SFG spectra exhibit strong peaks near 2865 and 2935 cm(-1) related to aligned leucine side chains interacting with the hydrophobic surface. Water modes near 3200 and 3400 cm(-1) indicate ordering of water molecules in the adsorbed-peptide fluorocarbon surface interfacial region. Amide I peaks observed near 1655 cm(-1) confirm that the secondary structure is preserved in the adsorbed peptide. A kinetic study of the film formation process using XPS and SFG showed rapid adsorption of the peptides followed by a longer assembly process. Peptide SFG spectra taken at the air-buffer interface showed features related to well-ordered peptide films. Moving samples through the buffer surface led to the transfer of ordered peptide films onto the substrates.
authors.affiliation: Department of Bioengineering and Department of Chemical Engineering, National ESCA and Surface Analysis Center for Biomedical Problems, University of Washington, Seattle, Washington 98195, USA.
authors.forename: Tobias
authors.initials: T
authors.lastname: Weidner
authors.forename: Newton T
authors.initials: NT
authors.lastname: Samuel
authors.forename: Keith
authors.initials: K
authors.lastname: McCrea
authors.forename: Lara J
authors.initials: LJ
authors.lastname: Gamble
authors.forename: Robert S
authors.initials: RS
authors.lastname: Ward
authors.forename: David G
authors.initials: DG
authors.lastname: Castner
mesh_terms: D000327:Adsorption; D002942:Circular Dichroism; D005466:Fluorocarbons / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D056951:Photoelectron Spectroscopy; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D013499:Surface Properties; D056928:X-Ray Absorption Spectroscopy
chemical_list: D005466:Fluorocarbons; D010455:Peptides; D009584:Nitrogen; D010100:Oxygen
references.citation: J Am Chem Soc. 2006 Mar 22;128(11):3598-607
references.pmid: 16536533
references.citation: Biophys J. 2004 Jun;86(6):3750-8
references.pmid: 15189871
references.citation: J Electron Spectros Relat Phenomena. 2009 May 1;172(1-3):2-8
references.pmid: 20161353
references.citation: J Am Chem Soc. 2008 Oct 1;130(39):13033-9
references.pmid: 18774819
references.citation: Biomaterials. 2006 Jun;27(18):3451-8
references.pmid: 16497372
references.citation: Eur J Vasc Endovasc Surg. 1996 Oct;12(3):321-30
references.pmid: 8896475
references.citation: Biophys J. 1999 Aug;77(2):903-14
references.pmid: 10423435
references.citation: Biotechnol Bioeng. 1994 Apr 5;43(8):772-80
references.pmid: 18615801
references.citation: J Biomed Mater Res. 1998 Jun 15;40(4):511-9
references.pmid: 9599026
references.citation: Phys Rev Lett. 1987 Oct 5;59(14):1597-1600
references.pmid: 10035277
references.citation: Appl Spectrosc. 2008 Sep;62(9):937-40
references.pmid: 18801230
references.citation: J Phys Chem B. 2009 Nov 26;113(47):15423-6
references.pmid: 19873996
references.citation: J Phys Chem B. 2005 Nov 24;109(46):22027-35
references.pmid: 16853860
references.citation: J Biomater Sci Polym Ed. 2001;12(9):961-78
references.pmid: 11787523
references.citation: Phys Rev Lett. 2008 Mar 7;100(9):096102
references.pmid: 18352727
references.citation: Biomaterials. 1999 Dec;20(23-24):2265-79
references.pmid: 10614933
references.citation: J Phys Chem B. 2006 Mar 16;110(10):5017-24
references.pmid: 16526745
references.citation: Science. 1992 Aug 14;257(5072):919-27
references.pmid: 1323877
references.citation: Biomaterials. 2000 Feb;21(3):267-72
references.pmid: 10646943
references.citation: Langmuir. 2010 Mar 2;26(5):3423-32
references.pmid: 19891457
references.citation: Science. 1994 May 6;264(5160):826-8
references.pmid: 17794723
references.citation: Annu Rev Biomed Eng. 2004;6:41-75
references.pmid: 15255762
references.citation: Biochemistry. 1996 Jul 23;35(29):9526-32
references.pmid: 8755733
references.citation: Eur J Biochem. 2003 May;270(10):2207-17
references.pmid: 12752440
references.citation: Biochim Biophys Acta. 1999 Jan 12;1416(1-2):176-94
references.pmid: 9889361
references.citation: Biomaterials. 2002 Dec;23(24):4847-54
references.pmid: 12361625
references.citation: Langmuir. 2005 Mar 29;21(7):2662-4
references.pmid: 15779931
references.citation: J Am Chem Soc. 2002 Jun 5;124(22):6297-303
references.pmid: 12033857
references.citation: J Am Chem Soc. 2009 Oct 14;131(40):14148-9
references.pmid: 19764755