title: Structure of biodegradable films at aqueous surfaces: X-ray diffraction and spectroscopy studies of polylactides and tyrosine-derived polycarbonates.
abstract: Three representative polymers of increasing modulus, poly(d,l-lactic acid), PDLLA, poly(desaminotyrosyl-tyrosine ethyl ester carbonate), PDTEC, and the same polymer with iodinated DTE segments, PI2DTEC, were characterized by surface-pressure versus area (Π-A) isotherms and surface sensitive X-ray diffraction techniques. Films of 10-100 Å thickness were prepared for these studies by spreading dilute polymer solutions at air-water interfaces. The general properties of the isotherms and the Flory exponents, determined from the isotherms, vary in accordance with the increasing modulus of PDLLA, PDTEC, PI2DTEC, respectively. The analysis of in situ X-ray reflectivity and grazing incidence X-ray diffraction (GIXD) measurements from films at aqueous surfaces provides a morphological picture that is consistent with the modulus of the polymers, and to a large extent, with their packing in their dry-bulk state. Large absorption of X-rays by iodine enabled X-ray spectroscopic studies under near-total-reflection conditions to determine the iodine distribution in the PI2DTEC film and complement the structural model derived from reflectivity and GIXD. These structural studies lay the foundation for future studies of polymer-protein interactions at aqueous interfaces.
authors.affiliation: Ames Laboratory and Department of Physics and Astronomy, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Wang
authors.forename: N Sanjeeva
authors.initials: NS
authors.lastname: Murthy
authors.forename: Ivan
authors.initials: I
authors.lastname: Kuzmenko
authors.forename: Nathaniel A
authors.initials: NA
authors.lastname: Anderson
authors.forename: David
authors.initials: D
authors.lastname: Vaknin
mesh_terms: D011076:Polycarboxylate Cement / Q000737:chemistry* / Q000378:metabolism; D011091:Polyesters / Q000737:chemistry* / Q000378:metabolism; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D014443:Tyrosine / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D011076:Polycarboxylate Cement; D011091:Polyesters; D014867:Water; C005506:polycarbonate; D014443:Tyrosine; C033616:poly(lactide)
references.citation: Langmuir. 2009 Oct 6;25(19):11528-32
references.pmid: 19489588
references.citation: Expert Rev Med Devices. 2005 Nov;2(6):667-71
references.pmid: 16293093
references.citation: Phys Rev Lett. 2005 Jul 29;95(5):056103
references.pmid: 16090892
references.citation: Eur Phys J E Soft Matter. 2002 Nov;9(4):375-85
references.pmid: 15010908
references.citation: Adv Drug Deliv Rev. 2003 Apr 25;55(4):447-66
references.pmid: 12706045
references.citation: Phys Rev B Condens Matter. 1988 Aug 1;38(4):2297-2311
references.pmid: 9946532
references.citation: Phys Rev Lett. 2011 Feb 4;106(5):056102
references.pmid: 21405412
references.citation: Biomaterials. 1997 Mar;18(5):405-13
references.pmid: 9061181
references.citation: Polymer (Guildf). 2010 Aug 4;51(17):3978-3988
references.pmid: 20802835
references.citation: Macromolecules. 2012 Jun 12;45(11):4896-4906
references.pmid: 22707795
references.citation: J Biomed Mater Res. 1994 Aug;28(8):919-30
references.pmid: 7983090
references.citation: Langmuir. 2010 Aug 17;26(16):13429-35
references.pmid: 20695588
references.citation: Phys Rev Lett. 1993 Feb 15;70(7):958-961
references.pmid: 10054248
references.citation: Langmuir. 2012 Mar 6;28(9):4274-82
references.pmid: 22316331
references.citation: Science. 1993 Aug 20;261(5124):1018-21
references.pmid: 17739620
references.citation: Phys Chem Chem Phys. 2008 Mar 14;10(10):1448-56
references.pmid: 18309402
references.citation: Nat Mater. 2004 Nov;3(11):745-7
references.pmid: 15516948
references.citation: Phys Rev Lett. 2012 Feb 3;108(5):055502
references.pmid: 22400939
references.citation: Biomacromolecules. 2003 Sep-Oct;4(5):1099-120
references.pmid: 12959572
references.citation: Langmuir. 2012 Aug 7;28(31):11555-66
references.pmid: 22830444
references.citation: Biomaterials. 1998 Mar;19(4-5):397-406
references.pmid: 9677153
references.citation: J Chem Phys. 2008 Jul 28;129(4):044504
references.pmid: 18681657