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Molecular synergy in biolubrication: The role of cartilage oligomeric matrix protein (COMP) in surface-structuring of lubricin
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
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(English)Manuscript (preprint) (Other academic)
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-156655OAI: oai:DiVA.org:kth-156655DiVA: diva2:767651
Note

QCR 20170221

Available from: 2014-12-02 Created: 2014-12-02 Last updated: 2017-02-21Bibliographically approved
In thesis
1. Biolubricants and Biolubrication
Open this publication in new window or tab >>Biolubricants and Biolubrication
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The main objective of this thesis work was to gain understanding of the principles of biolubrication, focusing on synergistic effects between biolubricants. To this end surface force and friction measurements were carried out by means of Atomic Force Microscopy, using hydrophilic and hydrophobic model surfaces in salt solutions of high ionic strength (≈ 150 mM) in presence of different biolubricants. There was also a need to gain information on the adsorbed layers formed by the biolubricants. This was achieved by using a range of methods such as Atomic Force Microscopy PeakForce imaging, Quartz Crystal Microbalance with Dissipation, Dynamic Light Scattering and X-Ray Reflectometry. By combining data from these techniques, detailed information about the adsorbed layers could be obtained.The biolubricants that were chosen for investigation were a phospholipid, hyaluronan, lubricin, and cartilage oligomeric matrix protein (COMP) that all exist in the synovial joint area. First the lubrication ability of these components alone was investigated, and then focus was turned to two pairs that are known or assumed to associate in the synovial area. Of the biolubricants that were investigated, it was only the phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) that was found to be an efficient lubricant on its own. Deposited DPPC bilayers on silica surfaces were found to be able to provide very low friction coefficients (≈ 0.01) up to high pressures, ≈ 50 MPa. A higher load bearing capacity was found for DPPC in the liquid crystalline state compared to in the gel state.The first synergy pair that was explored was DPPC and hyaluronan, that is known to associate on the cartilage surface, and we also noticed association between hyaluronan and DPPC vesicles as well as with adsorbed DPPC bilayers. By combining these two components a lubrication performance similar to that of DPPC alone could be achieved, even though the friction coefficient in presence of hyaluronan was found to be slightly higher. The synergy here is thus not in form of an increased performance, but rather that the presence of hyaluronan allows a large amount of the phospholipid lubricant to accumulate where it is needed, i.e. on the sliding surfaces.The other synergy pair was lubricin and COMP that recently has been shown to be co-localized on the cartilage surface, and thus suggested to associate with each other. Lubricin, as a single component, provided poor lubrication of PMMA surfaces, which we utilized as model hydrophobic surfaces. However, if COMP first was allowed to coat the surface, and then lubricin was added a low friction coefficient (≈ 0.03) was found. In this case the synergy arises from COMP facilitating strong anchoring of lubricin to the surface in conformations that provide good lubrication performance.

Abstract [sv]

Huvudsyftet med det här avhandlingsarbetet var att öka förståelsen för den låga friktion som finns i vissa biologiska system, med fokus på synergistiska effekter mellan de smörjande molekylerna. För detta ändamål studerades ytkrafter och friktion med hjälp av atomkraftsmikroskopi. Mätningarna utfördes med hydrofila och hydrofoba modellytor i lösningar med hög salthalt (≈ 150 mM) i närvaro av smörjande biomolekyler. Det var också nödvändigt att få information om de adsorberade skikten av biomolekyler. Det åstadkoms med hjälp av en rad tekniker så som AFM PeakForce avbildning, kvartskristallmikrovåg, dynamisk ljusspridning och röntgen reflektometri. Genom att kombinera data från dessa tekniker erhölls detaljerad information om de smörjande skikten.De smörjande biomolekyler som valdes ut för studierna var en fosfolipid, hyaluronan, lubricin, and cartilage oligomeric matrix protein (COMP) vilka alla finns i synovialledsområdet. Först undersöktes den smörjande förmågan hos dessa komponenter var för sig, och sedan fokuserade vi på två par av biomolekyler som man vet eller antar bildar associationsstrukturer i synovialleder. Av de enskilda biomolekyler som undersöktes var det endast fosfolipiden 1,2-dipalmitoyl-sn-glycero-3-fosfokoline (DPPC) som visade sig vara en effektivt smörjande molekyl. Deponerade biskikt av DPPC på silikaytor gav upphov till mycket låga friktionskoefficienter (≈ 0.01) upp till höga pålagda tryck, ≈ 50 MPa. DPPC bilager i flytande kristallin fas visade sig ha högre lastbärande förmåga än DPPC bilager i geltillstånd.Det första synergistiska par som undersöktes var DPPC och hyaluronan vilka man vet associerar på broskytan, och vi visade att hyaluronan associerar med såväl DPPC vesiklar som med DPPC bilager. Genom att kombinera dessa två komponenter uppmättes en smörjande förmåga som var jämförbar med den som DPPC ensam uppvisar. Även om friktionskoefficienten var något högre i närvaro av hyaluronan. Synergieffekten här består inte av en bättre smörjande förmåga, utan istället gör närvaron av hyaluronan att de smörjande fosfolipiderna kan ansamlas i stora mängder där de behövs, dvs. på de glidande ytorna.Det andra synergiparet var lubricin och COMP vilka nyligen har visats vara lokaliserade på samma platser på broskytan, vilket tyder på att de associerar med varandra. På egen hand var lubricins smörjande förmåga av PMMA, våra hydrofoba modellytor, dålig. Emellertid, om COMP först adsorberades på PMMA och sedan lubricin tillsattes uppmättes en låg friktionskoefficient (≈ 0.03). I det här fallet består synergin av att COMP möjliggör en stark inbindning till ytan av lubricin i konformationer som ger god smörjande förmåga.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. vi, 62 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2014:56
Keyword
Hyaluronan, Phospholipid, Lubricin, Cartilage Oligomeric Matrix Protein, COMP, Adsorption, Surface Force, Friction, Biolubrication, Boundary Lubrication, Load Bearing Capacity, Synergistic Effects, DLS, QCM-D, AFM., Hyaluronan, Fosfolipid, Lubricin, Cartilage Oligomeric Matrix Protein, COMP, Adsorption, Ytkraft, Friktion, Biologisk smörjning, Gränsskiktssmörjning, Lastbärande förmåga, Synergieffekter, DLS, QCM-D, AFM.
National Category
Physical Chemistry Polymer Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-156632 (URN)978-91-7595-348-9 (ISBN)
Public defence
2014-12-16, E3, Osquarsbacke 14, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Projects
Stiftelsen för strategisk forskning - SSF
Note

QC 20141202

Available from: 2014-12-02 Created: 2014-12-01 Last updated: 2014-12-02Bibliographically approved
2. Synergies in Biolubrication
Open this publication in new window or tab >>Synergies in Biolubrication
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The objective of this thesis was to advance understanding in the field of biolubrication, finding inspiration from the human synovial joints. This was addressed by investigating the association of key biolubricants and the resulting lubrication performance. Techniques employed during the course of this work were Atomic force microscopy (AFM), Quartz crystal microbalance with dissipation monitoring (QCM-D), X-ray reflectivity (XRR).

Key synovial fluid and cartilage components like dipalmitoylphosphatidylcholine (DPPC), hyaluronan (HA), lubricin, and cartilage oligomeric matrix protein (COMP) have been used in the investigations. Focus was towards two lubrication couples; DPPC-hyaluronan and COMP-lubricin. DPPC-hyaluronan mixtures were probed on hydrophilic silica surfaces and COMP-lubricin association structures were explored on weakly hydrophobic poly (methyl methacrylate) (PMMA) surfaces.

Investigations of the COMP-lubricin pair revealed that individually these components are unable to reach desired lubrication. However in combination, COMP facilitates firm attachment of lubricin to the PMMA surface in a favourable confirmation that imparts low friction coefficient.

DPPC and hyaluronan combined impart lubrication advantage over lone DPPC bilayers. Hyaluronan provides a reservoir of DPPC on the surface and consequently self-healing ability.

Other factors like temperature, presence of calcium ions, molecular weight of hyaluronan, and pressure were also explored. DPPC bilayers at higher temperature had higher load bearing capacity. Association between DPPC Langmuir layers and hyaluronan was enhanced in the presence of calcium ions, and lower molecular weight hyaluronan had a stronger tendency to bind to DPPC. At high pressures, DPPC-hyaluronan layers were more stable compared to lone DPPC bilayers.

Place, publisher, year, edition, pages
Sweden: KTH Royal Institute of Technology, 2017. 66 p.
Series
TRITA-CHE-Report, ISSN 1654-1081
Keyword
Biolubrication, Synergies, Adsorption, Surface Force, Friction, Load Bearing Capacity, Self Healing, Phospholipids, DPPC, Hyaluronan, COMP, Lubricin, QCM-D, AFM, XRR.
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-201219 (URN)978-91-7729-268-5 (ISBN)
Public defence
2017-03-17, Kollegiesalen, KTH, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20170210

Available from: 2017-02-10 Created: 2017-02-09 Last updated: 2017-02-13Bibliographically approved

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