title: Elasticity of native and cross-linked polyelectrolyte multilayer films.
abstract: Mechanical properties of polyelectrolyte multilayer films were studied by nanoindentation using the atomic force microscope (AFM). Force-distance measurements using colloidal probe tips were systematically obtained for supported films of poly(L-lysine) and hyaluronan that are suited to bio-application. Both native and covalently cross-linked films were studied as a function of increasing layer number, which increases film thickness. The effective Young's modulus perpendicular to the film, Eperpendicular, was determined to be a function of film thickness, cross-linking, and sample age. Thick PEM films exhibited a lower Eperpendicular than thinner PEM, whereas the Young's modulus of cross-linked films was more than 10-fold larger than native films. Moduli range from approximately 20 kPa for native films up to approximately 800 kPa for cross-linked ones. Young's moduli increased slightly with sample age, plateauing after approximately 4 weeks. Spreading of smooth muscle cells on these substrates with pre-attached collagen proved to be highly dependent on film rigidity with stiffer films giving greater cell spreading.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, Unité 595, Université Louis Pasteur, 11 rue Humann, 67085 Strasbourg Cedex, France.
authors.forename: Ludovic
authors.initials: L
authors.lastname: Richert
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Engler
authors.forename: Dennis E
authors.initials: DE
authors.lastname: Discher
authors.forename: Catherine
authors.initials: C
authors.lastname: Picart
mesh_terms: D003432:Cross-Linking Reagents / Q000032:analysis / Q000737:chemistry*; D004548:Elasticity; D004573:Electrolytes / Q000032:analysis / Q000737:chemistry; D006820:Hyaluronic Acid / Q000032:analysis / Q000737:chemistry*; D011107:Polylysine / Q000032:analysis / Q000737:chemistry*; D012996:Solutions / Q000032:analysis / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D004573:Electrolytes; D012996:Solutions; D011107:Polylysine; D006820:Hyaluronic Acid