title: The influence of hyaluronan on the structure of a DPPC-bilayer under high pressures.
abstract: The superior lubrication properties of synovial joints have inspired many studies aiming at uncovering the molecular mechanisms which give rise to low friction and wear. However, the mechanisms are not fully understood yet, and, in particular, it has not been elucidated how the biolubricants present at the interface of cartilage respond to high pressures, which arise during high loads of joints. In this study we utilize a simple model system composed of two biomolecules that have been implied as being important for joint lubrication. It consists of a solid supported dipalmitoylphosphatidylcholin (DPPC) bilayer, which was formed via vesicles fusion on a flat Si wafer, and the anionic polysaccharide hyaluronan (HA). We first characterized the structure of the HA layer that adsorbed to the DPPC bilayers at ambient pressure and different temperatures using X-ray reflectivity (XRR) measurements. Next, XRR was utilized to evaluate the response of the system to high hydrostatic pressures, up to 2kbar (200MPa), at three different temperatures. By means of fluorescence microscopy images the distribution of DPPC and HA on the surface was visualized. Our data suggest that HA adsorbs to the headgroup region that is oriented towards the water side of the supported bilayer. Phase transitions of the bilayer in response to temperature and pressure changes were also observed in presence and absence of HA. Our results reveal a higher stability against high hydrostatic pressures for DPPC/HA composite layers compared to that of the DPPC bilayer in absence of HA.
authors.affiliation: Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Straße, 21502 Geesthacht, Germany. Electronic address: Thomas.Zander@hzg.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Zander
authors.affiliation: Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Straße, 21502 Geesthacht, Germany.
authors.forename: D C Florian
authors.initials: DCF
authors.lastname: Wieland
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science,Drottning Kristinas väg 51, SE-10044 Stockholm, Sweden.
authors.forename: Akanksha
authors.initials: A
authors.lastname: Raj
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science,Drottning Kristinas väg 51, SE-10044 Stockholm, Sweden.
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.affiliation: Fakultät Physik/DELTA, TU Dortmund, 44221 Dortmund, Germany.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Nowak
authors.affiliation: Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Straße, 21502 Geesthacht, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Krywka
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science,Drottning Kristinas väg 51, SE-10044 Stockholm, Sweden; SP Technical Research Institute of Sweden, SP Chemistry, Materials and Surfaces, Box 5607, SE-114 86 Stockholm, Sweden.
authors.forename: Andra
authors.initials: A
authors.lastname: Dėdinaitė
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science,Drottning Kristinas väg 51, SE-10044 Stockholm, Sweden; SP Technical Research Institute of Sweden, SP Chemistry, Materials and Surfaces, Box 5607, SE-114 86 Stockholm, Sweden.
authors.forename: Per Martin
authors.initials: PM
authors.lastname: Claesson
authors.affiliation: Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Straße, 21502 Geesthacht, Germany.
authors.forename: Vasil M
authors.initials: VM
authors.lastname: Garamus
authors.affiliation: Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Straße, 21502 Geesthacht, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schreyer
authors.affiliation: Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Straße, 21502 Geesthacht, Germany.
authors.forename: Regine
authors.initials: R
authors.lastname: Willumeit-Römer
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D000327:Adsorption; D001393:Azoles / Q000737:chemistry; D040761:Biomimetic Materials / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D017276:Friction; D006801:Humans; D006820:Hyaluronic Acid / Q000737:chemistry*; D006874:Hydrostatic Pressure; D007596:Joints / Q000502:physiology; D008051:Lipid Bilayers / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D009578:Nitrobenzenes / Q000737:chemistry; D012235:Rhodamines / Q000737:chemistry; D013499:Surface Properties; D013582:Synovial Fluid / Q000737:chemistry / Q000502:physiology; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: C437523:5-carboxytetramethylrhodamine; C510797:7-nitrobenz-2-oxa-1,3-diazol-4-yl; D001393:Azoles; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D009578:Nitrobenzenes; D012235:Rhodamines; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine; D006820:Hyaluronic Acid
keywords: High pressure; Hyaluronan; Lubrication; Supported DPPC bilayer; Synovial joint; Vesicle fusion; X-ray reflectivity