title: Physical and biological properties of barium cross-linked alginate membranes.
abstract: We describe the manufacture of highly stable and elastic alginate membranes with good cell adhesivity and adjustable permeability. Clinical grade, ultra-high viscosity alginate is gelled by diffusion of Ba2+ followed by use of the "crystal gun" [Zimmermann H. et al., Fabrication of homogeneously cross-linked, functional alginate microcapsules validated by NMR-, CLSM- and AFM-imaging. Biomaterials 2003;24:2083-96]. Burst pressure of well-hydrated membranes is between 34 and 325kPa depending on manufacture and storage details. Water flows induced by sorbitol and raffinose (probably diffusional) are lower than those caused by PEG 6000, which may be related to a Hagen-Poiseuille flow. Hydraulic conductivity, L(p), from PEG-induced flows ranges between 2.4x10(-12) and 6.5x10(-12) m Pa(-1)s(-1). Hydraulic conductivity measured with hydrostatic pressure up to 6 kPa is 2-3 orders of magnitude higher and decreases with increasing pressure to about 3x10(-10) m Pa(-1)s(-1) at 4kPa. Mechanical introduction of 200 microm-diameter pores increases hydraulic conductivity dramatically without loss of mechanical stability or flexibility. NMR imaging with Cu2+ as contrast agent shows a layered structure in membranes cross-linked for 2h. Phase contrast and atomic force microscopy in liquid environment reveals surface protrusions and cavities correlating with steps of the production process. Murine L929 cells adhere strongly to the rough surface of crystal-bombarded membranes. NaCl-mediated membrane swelling can be prevented by partial replacement of salt with sorbitol allowing cell culture on the membranes.
authors.affiliation: Abteilung Kryobiophysik & Kryotechnologie, Fraunhofer-Institut für Biomedizinische Technik, D-66386 St. Ingbert, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Zimmermann
authors.forename: Felix
authors.initials: F
authors.lastname: Wählisch
authors.forename: Claudia
authors.initials: C
authors.lastname: Baier
authors.forename: Markus
authors.initials: M
authors.lastname: Westhoff
authors.forename: Randolph
authors.initials: R
authors.lastname: Reuss
authors.forename: Dirk
authors.initials: D
authors.lastname: Zimmermann
authors.forename: Marcus
authors.initials: M
authors.lastname: Behringer
authors.forename: Friederike
authors.initials: F
authors.lastname: Ehrhart
authors.forename: Alisa
authors.initials: A
authors.lastname: Katsen-Globa
authors.forename: Christoph
authors.initials: C
authors.lastname: Giese
authors.forename: Uwe
authors.initials: U
authors.lastname: Marx
authors.forename: Vladimir L
authors.initials: VL
authors.lastname: Sukhorukov
authors.forename: Julio A
authors.initials: JA
authors.lastname: Vásquez
authors.forename: Peter
authors.initials: P
authors.lastname: Jakob
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Shirley
authors.forename: Ulrich
authors.initials: U
authors.lastname: Zimmermann
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000818:Animals; D001464:Barium; D001672:Biocompatible Materials / Q000737:chemistry*; D001696:Biomechanical Phenomena; D002214:Capsules; D002448:Cell Adhesion; D002460:Cell Line; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003432:Cross-Linking Reagents; D004058:Diffusion; D004548:Elasticity; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006874:Hydrostatic Pressure; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D008567:Membranes, Artificial; D051379:Mice; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008962:Models, Theoretical; D009995:Osmosis; D013499:Surface Properties; D014867:Water
chemical_list: D000464:Alginates; D001672:Biocompatible Materials; D002214:Capsules; D003432:Cross-Linking Reagents; D006603:Hexuronic Acids; D008567:Membranes, Artificial; D014867:Water; D001464:Barium; D020723:Glucuronic Acid