title: Influence of pH on the build-up of poly-L-lysine/heparin multilayers.
abstract: The effect of pH on the build-up of polyelectrolyte multilayers, PEMs, composed by poly-L-lysine and heparin onto two different substrates, silica and gold, has been studied by means of ellipsometry and quartz crystal microbalance with dissipation, QCM-D. Ellipsometry results indicate that the dry mass grows exponentially with the number of layers, and that this amount is larger as the pH values are raised. From QCM-D data the viscoelastic properties of the multilayered structure have been obtained. These data reflect that PEMs become more viscoelastic as the pH values are increased for silica substrates, while for gold the highest viscoelastic behavior is obtained at neutral pH and the elastic behavior becomes dominant as the pH is further increased or decreased. By combining these two surface techniques it has been also possible to determine the solvent content in the multilayers and reach a deeper understanding of the internal structure.
authors.affiliation: Biomedical Science, Faculty of Health and Society, Malmoe University, Skåne University Hospital, Malmoe, Sweden. alejandro.barrantes@mah.se
authors.forename: Alejandro
authors.initials: A
authors.lastname: Barrantes
authors.forename: Olga
authors.initials: O
authors.lastname: Santos
authors.forename: Javier
authors.initials: J
authors.lastname: Sotres
authors.forename: Thomas
authors.initials: T
authors.lastname: Arnebrant
mesh_terms: D000327:Adsorption; D004548:Elasticity; D006046:Gold / Q000737:chemistry*; D006493:Heparin / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D011107:Polylysine / Q000737:chemistry*; D011791:Quartz / Q000737:chemistry; D058525:Quartz Crystal Microbalance Techniques; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D014783:Viscosity
chemical_list: D011791:Quartz; D011107:Polylysine; D006046:Gold; D012822:Silicon Dioxide; D006493:Heparin