title: The effect of temperature on supported dipalmitoylphosphatidylcholine (DPPC) bilayers: structure and lubrication performance.
abstract: Phospholipids fulfill an important role in joint lubrication. They, together with hyaluronan and glycoproteins, are the biolubricants that sustain low friction between cartilage surfaces bathed in synovial fluid. In this work we have investigated how the friction force and load bearing capacity of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers on silica surfaces are affected by temperature, covering the temperature range 25-52°C. Friction forces have been determined utilizing the AFM colloidal probe technique, which showed that DPPC bilayers are able to provide low friction forces over the whole temperature interval. However, the load bearing capacity is improved at higher temperatures. We interpret this finding as being a consequence of lower rigidity and higher self-healing capacity of the DPPC bilayer in the liquid disordered state compared to the gel state. The corresponding structure of solid supported DPPC bilayers at the silica-liquid interface has been followed using X-ray reflectivity measurements, which suggests that the DPPC bilayer is in the gel phase at 25°C and 39°C and in the liquid disordered state at 55°C. Well-defined bilayer structures were observed for both phases. The deposited DPPC bilayers were also imaged using AFM PeakForce Tapping mode, and these measurements indicated a less homogeneous layer at temperatures below 37°C.
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: Helmholtz Zentrum Geesthacht, Institute for Materials Research, Max-Planck Straße 1, 21502 Geesthacht, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Zander
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: Xiaoyan
authors.initials: X
authors.lastname: Liu
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: Chao
authors.initials: C
authors.lastname: Liu
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: Helmholtz Zentrum Geesthacht, Institute for Materials Research, Max-Planck Straße 1, 21502 Geesthacht, Germany.
authors.forename: D C
authors.initials: DC
authors.lastname: Florian Wieland
authors.affiliation: Helmholtz Zentrum Geesthacht, Institute for Materials Research, Max-Planck Straße 1, 21502 Geesthacht, Germany.
authors.forename: Vasil M
authors.initials: VM
authors.lastname: Garamus
authors.affiliation: Helmholtz Zentrum Geesthacht, Institute for Materials Research, Max-Planck Straße 1, 21502 Geesthacht, Germany.
authors.forename: Regine
authors.initials: R
authors.lastname: Willumeit-Römer
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: 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. Electronic address: andra@kth.se.
authors.forename: Andra
authors.initials: A
authors.lastname: Dėdinaitė
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000031:analogs & derivatives* / Q000737:chemistry; D017276:Friction; D008051:Lipid Bilayers / Q000737:chemistry*; D008153:Lubrication; D013499:Surface Properties; D013696:Temperature
chemical_list: D008051:Lipid Bilayers; D015060:1,2-Dipalmitoylphosphatidylcholine; C081581:colfosceril palmitate
keywords: AFM; DPPC; Friction; Load bearing capacity; Lubrication; Phospholipid bilayer; Surface forces; X-ray reflectivity